Saturday, June 06, 2009

High Cholesterol protects against Infections

A very good read..Many researchers have suggested that the blood lipids play a key role in the immune defence system. There is also a growing understanding that an inflammatory response of the arterial intima to injury is a crucial step in the genesis of atherosclerosis. and that infections may be one type of such injury.22 These two concepts are difficult to harmonize with the low-density-lipoprotein (LDL) receptor hypothesis, according to which high LDL cholesterol is the most important cause of atherosclerosis. However, the many observations that conflict with the LDL receptor hypothesis, may be explained by the idea that high serum cholesterol and/or high LDL is protective against infection and atherosclerosis.

Read the whole article here

Tuesday, June 02, 2009

Old Genes Can Learn New Tricks, Horned Beetles Show

A popular view among evolutionary biologists that fundamental genes do not acquire new functions has been challenged by a new study in the Proceedings of the National Academy of Sciences.

Indiana University Bloomington biologist Armin Moczek and research associate Debra Rose report that two ancient genes were "co-opted" to help build a new trait in beetles -- the fancy antlers that give horned beetles their name. The genes, Distal-less and homothorax, touch most aspects of insect larval development, and have therefore been considered off-limits to the evolution of new traits. In the two horned beetle species Moczek and Rose studied, the genetic sequences of Distal-less and homothorax were hardly different, suggesting the two genes have retained their unique identities because of selective pressures not to change. What changed was not the genes themselves, but when and where they are turned on.

"Evolutionary biologists have a good idea of what it takes to change the shape of a wing, the length of a leg, or the anatomy of an eye," Moczek said. "What we have struggled with, though, is how these traits originate in the first place. How do you evolve that first wing, limb or photoreceptor from a flightless, limbless and blind ancestor?"

To investigate these questions, Moczek and Rose examined three development genes that are so old, all insects have them: Distal-less, homothorax and a third, dachshund. The genes were first characterized in fruit flies, and are categorized as "upstream" regulatory genes because they influence a wide variety of genetic processes in insect cells, such as the development of legs, antennae and wings. Moczek said that in horned beetles, each of the three genes is likely to have hundreds to thousands of downstream targets.

A tenuous consensus among evolutionary biologists was that such genes -- upon which so many different and important processes depend -- could not be easily modified, because any modification would affect countless aspects of the insect's development, any one of which could be bad for the individual insect, reducing its fitness relative to its peers.

Moczek and Rose's PNAS paper confirms one aspect of this idea. All three genes were sequenced and found to be highly conserved, or unchanged, not only among the individuals of each beetle species they examined, but also between the two species, Onthophagus taurus (Italy) and Onthophagus binodis (South Africa), whose lineages diverged about 24 million years ago. But that isn't the whole story.

To understand the effects of the three genes on horned beetle development, Moczek and Rose employed a new and promising technique, RNA interference, which disables the action of specific genes without compromising other genetic processes. Humans are only mimicking nature here; RNA interference is also a natural method of gene regulation in eukaryotes.

Moczek and Rose divided beetle larvae of both species into three treatment groups: no injection, buffer injection with nonsense RNA and buffer injection with RNA interference transcripts designed to disrupt one of three crucial developmental genes.

Moczek and Rose learned that two of the three genes, Distal-less and homothorax, are used by both O. taurus and O. binodis in the development of beetle horns. While Distal-less was found to affect both the development of thorax horns (which form just behind the head) and head horns, homothorax was only found to influence thorax horn development. The gene dachshund appears to have no effect whatsoever on horn development in either species.

"The evolution of novel features does not require the evolution of novel genes," Moczek said. "A lot of innovation can grow from within the organism's genetic toolbox."

More importantly, Moczek and Rose learned all developmental genes are candidates for such recruitment, not just the genes whose development functions are considered non-essential or limited in their effects.

Moczek also says the PNAS paper may compel evolutionary biologists to revisit pleiotropy, the foundational concept of one gene influencing many traits.

"It may be that our understanding of pleiotropy is too simplistic," Moczek said. "Now that we know fundamental development genes can acquire new and diverse functions with relative ease, pleiotropy may not be nearly as constraining as we have thought."

Monday, June 01, 2009

U.S. company finds "safer" way to make stem-like cells

U.S. researchers said on Thursday they had come up with the safest way yet to make stem-like cells using a patient's ordinary skin cells, this time by using pure human proteins. The team at Harvard University and Massachusetts-based Advanced Cell Technology Inc said their technique involves soaking cells in human proteins that turn back the clock biologically, making the cells behave like powerful embryonic stem cells.

Dr. Robert Lanza of Advanced Cell sees almost immediate commercial applications.

"After a few more flight tests -- in order to assure everything is working properly -- it should be ready for commercial use," Lanza said by e-mail.

He said the company would seek Food and Drug Administration permission to test the cells in people by next year -- a process unlikely to be quick, especially with a brand-new technology such as this one.

Stem cells are the body's master cells, giving rise to all the tissues, organs and blood. Embryonic stem cells are considered the most powerful kind, as each one is pluripotent, with the potential to morph into any type of tissue.

Doctors hope to someday use them to transform medicine, for instance, by regenerating the cells destroyed in type 1 diabetes or regrowing eye cells to reverse blindness.

But embryonic cells require the use of an embryo or cloning technology, and several countries, including the United States, limit funding for such experiments.

Several teams of scientists have homed in on four genes that can turn back the clock in ordinary cells, making them look and act like embryonic stem cells. These so-called induced pluripotent stem cells, or iPS cells, could in theory be made using a patient's own skin, allowing grow-your-own transplants with no risk of rejection.


Getting these genes into the cells is not easy, however.

The first attempts used retroviruses, which integrate their own genetic material into the cells they infect. Others used loops of genetic material called plasmids or other genetically engineered molecules to reformat the cells.

And another team used the proteins made by the four genes and valproic acid to reprogram cells, but Lanza said these methods all have drawbacks.

His team, working with Kwang-Soo Kim of the Harvard Stem Cell Institute and a team at CHA Stem Cell Institute in South Korea used a peptide, a protein fragment, to drag the human proteins into the cells.

"These have been around for a long time," Lanza said. "The AIDS virus uses the peptide to get into the cells it infects," he said.

Using cells from the foreskins of newborn boys -- a common laboratory technique -- they showed they could transform the cells into iPS cells. They regrew them into a variety of mature new cell types, they reported in the journal Cell Stem Cell.

"This method eliminates the risks associated with genetic and chemical manipulation, and provides for the first time a potentially safe source of iPS cells for translation into the clinic," Lanza said.

"This is the ultimate stem cell solution -- you just add some proteins to a few skin cells and voila! Patient-specific stem cells!"

One question that is not clear is who owns the technology. Lanza said many groups have tried to patent the various steps in the process and it is not yet clear whose patents will prevail.

Friday, May 29, 2009

New Cellular Targets For HIV Drug Development

Focusing HIV drug development on immune cells called macrophages instead of traditionally targeted T cells could bring us closer to eradicating the disease, according to new research from University of Florida and five other institutions.

In the largest study of its kind, researchers found that in diseased cells — such as cancer cells — that are also infected with HIV, almost all the virus was packed into macrophages, whose job is to "eat" invading disease agents.

What's more, up to half of those macrophages were hybrids, formed when pieces of genetic material from several parent HIV viruses combined to form new strains.

Such "recombination" is responsible for formation of mutants that easily elude immune system surveillance and escape from anti-HIV drugs.

"Macrophages are these little factories producing new hybrid particles of the virus, making the virus probably even more aggressive over time," said study co-author Marco Salemi, Ph.D., an assistant professor in the department of pathology, immunology and laboratory medicine at the UF College of Medicine. "If we want to eradicate HIV we need to find a way to actually target the virus specifically infecting the macrophages."

At least 1.1 million people in the United States and 33 million in the world are living with HIV/AIDS, according to the Kaiser Family Foundation.

The researchers set out to see if HIV populations that infect abnormal tissues are different from those that infect normal ones, and whether particular strains are associated with certain types of illness.

They tackled the question using frozen post-autopsy tissue samples, pathology results and advanced computational techniques. They analyzed 780 HIV sequences from 53 normal and abnormal tissues from seven patients who had died between 1995 and 2003 from various AIDS-related conditions, including HIV-associated dementia, non-Hodgkin's lymphoma and generalized infections throughout the body. Four patients had been treated with highly active antiretroviral therapy, called HAART, at or near the time of death.

The researchers compared brain and lymphoma tissues, which had heavy concentrations of macrophages, with lymphoid tissues — such as from the spleen and lymph nodes— that had a mix of HIV-infected macrophages and T cells.

The analyses revealed great diversity in the HIV strains present, with different tissues having hybrid viruses made up of slightly different sets of genes. A high frequency of such recombinant viruses was also found in tissues generally associated with disease processes, such as the meninges, spleen and lymph nodes.

The researchers concluded that HIV-infected macrophages might be implicated in tumor-producing mechanisms.

The higher frequency of recombinant virus in diseased tissues likely is because macrophages multiply as a result of an inflammatory response, the researchers said.

"The study points to macrophages as a site of recombination in active disease," said neurobiologist Kenneth C. Williams, Ph.D., a Boston College associate professor and AIDS expert who was not involved in the study. "So people can say this is one spot where these viruses come from."

T cells — the so-called conductors of the immune system orchestra, whose decline is the hallmark of HIV disease — are an obvious target for HIV drug development because they die soon after infection, and are readily sampled from the blood and cultured. But although current drugs are effective at blocking infection of new cells and lowering viral loads to barely detectable levels, they never reduce the viral level in an infected person to zero.

"Where is it coming from?" said Michael S. McGrath, the University of California, San Francisco, professor who led the research team. "We believe it's coming from these macrophages."

Macrophages, like T cells, can be infected multiple times by HIV. But unlike T cells, when they get infected, they don't die within days, but live for several months, all the while being re-infected with multiple viruses of different genetic makeup. That situation is ripe for the emergence of hybrids.

"Most people who look at viral sequences assume that evolution of the virus is linear. In the real world that doesn't happen — large parts of the virus are swapped in and out. This group has shown that in this model," Williams said. "It sort of overturns the old way of trying to match virus sequence with pathology."

McGrath's group is now developing macrophage-targeting drugs that, through a grant from the National Institute of Mental Health, should be in human clinical trials in a few years.

"This is one of the last frontiers — killing off what we believe is a so far untouched reservoir," he said.

The work was published recently in the journal PLoS One.

Sunday, May 24, 2009

Gene-laden Bubbles Grow New Blood Vessels

Progress in human gene therapy -- the insertion of therapeutic DNA into tissues and cells in the human body -- has been slower than expected since the first clinical trials in 1990. One of the biggest challenges for this technology is finding ways to safely and effectively deliver genes only to the specific parts of the body that they are meant to treat.

Cardiologist Jonathan Lindner of Oregon Health and Science University will discuss his latest experiments in gene therapy, which use microscopic bubbles chemically modified to stick to the cells that line blood vessels.

This technique, ultrasound-mediated gene delivery (UMGD), exploits the properties of contrast agents, microparticles that are normally injected into the body to improve the quality of ultrasound images. In UMGD, the tiny particles are microbubbles composed of pockets of gas encapsulated by thin membranes that are coated with DNA before injection. A targeted pulse of ultrasound energy "rings" the bubbles like a bell, popping them in a specific location and releasing the DNA into the surrounding tissue.

To improve the specificity of this targeting, Lindner grafts long arm-like molecules to the outside of the bubbles. These arms, which do not interfere with the DNA attached to surface, are designed to recognize and bind to molecules on the outside of specific cells in the body, allowing the bubbles to attach to a tissue before being popped. In theory, this should improve both the specificity and efficiency of the gene therapy.

Lindner created an arm designed to attach to endothelial cells lining blood vessels. He will present data evaluating the behavior of these "targeted" bubbles in living tissue. The ability to stick these gene-laden microbubbles to the lining of blood vessels increased the amount of gene transfection. This strategy may be particularly important for delivering therapeutic DNA to the walls of blood vessels. For example, Dr. Lindner and collaborators have successfully stimulated the growth of new blood vessels using UMGD with microbubbles carrying a gene for vascular endothelial growth factor. This therapeutic use could be important for treating ischemia in patients who have had a heart attack, peripheral artery disease, or stroke.

The team is also investigating using the bubbles to transport small doses of drugs. "If you're trying to deliver a nasty drug to part of the body, this may be a way to improve safety," says Lindner.

The talk "Targeted microbubble technology and ultrasound-mediated gene delivery" by Jonathan Lindner will be presented at the 157th  Acoustical Society of America Meeting to be held May 18-22 in Portland, Ore.

Saturday, May 16, 2009

Fish Oil Protects Against Diseases Like Parkinson's

Dr. Nicolas Bazan, Director of the Neuroscience Center of Excellence, Boyd Professor, and Ernest C. and Yvette C. Villere Chair of Retinal Degenerative Diseases Research at LSU Health Sciences Center New Orleans, will present new research findings showing that an omega three fatty acid in the diet protects brain cells by preventing the misfolding of a protein resulting from a gene mutation in neurodegenerative diseases like Parkinson's and Huntington's.

He will present these findings for the first time on April 19, 2009 at the Ernest N. Morial Convention Center, Nouvelle C Room, at the American Society for Nutrition, Experimental Biology 2009 Annual Meeting.

With funding from the National Eye Institute of the National Institutes of Health, Dr. Bazan and his colleagues developed a cell model with a mutation of the Ataxin-1 gene. The defective Ataxin-1 gene induces the misfolding of the protein produced by the gene. These misshapened proteins cannot be properly processed by the cell machinery, resulting in tangled clumps of toxic protein that eventually kill the cell. Spinocerebellar Ataxia, a disabling disorder that affects speech, eye movement, and hand coordination at early ages of life, is one disorder resulting from the Ataxin-1 misfolding defect. The research team led by Dr. Bazan found that the omega three fatty acid, docosahexaenoic acid (DHA), protects cells from this defect.

Dr. Bazan's laboratory discovered earlier that neuroprotectin D1 (NPD1), a naturally-occurring molecule in the human brain that is derived from DHA also promotes brain cell survival. In this system NPD1 is capable of rescue the dying cells with the pathological type of Ataxin-1, keeping their integrity intact.

"These experiments provide proof of principle that neuroprotectin D1 can be applied therapeutically to combat various neurodegenerative diseases," says Dr. Bazan. "Furthermore, this study provides the basis of new therapeutic approaches to manipulate retinal pigment epithelial cells to be used as a source of NPD1 to treat patients with disorders characterized by this mutation like Parkinson's, Retinitis Pigmentosa and some forms of Alzheimer's Disease."

Sunday, May 10, 2009

Earliest Evidence Of Domesticated Maize Discovered: Dates Back 8,700 Years

This is so fascinating. According to Ranere, recent studies have confirmed that maize derived from teosinte, a large wild grass that has five species growing in Mexico, Guatemala and Nicaragua. The teosinte species that is closest to maize is Balsas teosinte, which is native to Mexico's Central Balsas River Valley.

"We went to the area where the closest relative to maize grows, looked for the earliest maize and found it," said Ranere. "That wasn't surprising since molecular biologists had determined that Balsas teosinte was the ancestral species to maize. So it made sense that this was where we would find the earliest domestication of maize."

The study began with Piperno, a Temple University anthropology alumna, finding evidence in the form of pollen and charcoal in lake sediments that forests were being cut down and burned in the Central Balsas River Valley to create agricultural plots by 7000 years ago. She also found maize and squash phytoliths -- rigid microscopic bodies found in many plants -- in lakeside sediments.

Ranere, an archaeologist, joined in the study to find rock shelters or caves where people lived in that region thousands of years ago. His team carried out excavations in four of the 15 caves and rock shelters visited in the region, but only one of them yielded evidence for the early domestication of maize and squash.

Ranere excavated the site and recovered numerous grinding tools. Radiocarbon dating showed that the tools dated back at least 8700 years. Although grinding tools were found beneath the 8700 year level, the researchers were not able to obtain a radiocarbon date for the earliest deposits. Previously, the earliest evidence for the cultivation of maize came from Ranere and Piperno's earlier research in Panama where maize starch and phytoliths dated back 7600 years.

Ranere said that maize starch, which is different from teosinte starch, was found in crevices of many of the tools that were unearthed.

"We found maize starch in almost every tool that we analyzed, all the way down to the bottom of our site excavations," Ranere said. "We also found phytoliths that comes from maize or corn cobs, and since teosinte doesn't have cobs, we knew we had something that had changed from its wild form."

Ranere said that their findings also supported the premise that maize was domesticated in a lowland seasonal forest context, as opposed to being domesticated in the arid highlands as many researchers had once believed.

"For a long time, I though it strange that researchers argued about the location and age of maize domestication yet never looked in the Central Balsas River Valley, the homeland for the wild ancestor," said Ranere. "Dolores was the first one to do it.'

In addition to Ranere and Piperno, other researchers in the study included Irene Holst of the Smithsonian Tropical Research Institute, Ruth Dickau of Temple, and Jose Iriarte of the University of Exeter. The study was funded by the National Science Foundation, National Geographic Society, Wenner-Gren Foundation, Smithsonian National Museum of Natural History, Smithsonian Tropical Research Institute and the Temple University College of Liberal Arts.

Wednesday, May 06, 2009

Glucose-To-Glycerol Conversion In Long-lived Yeast Provides Anti-aging Effects

Cell biologists have found a more filling substitute for caloric restriction in extending the life span of simple organisms. In a study published May 8 in the open-access journal PLoS Genetics, researchers from the University of Southern California Andrus Gerontology Center show that yeast cells maintained on a glycerol diet live twice as long as normal -- as long as yeast cells on a severe caloric-restriction diet. They are also more resistant to cell damage.

Many studies have shown that caloric restriction can extend the life span of a variety of laboratory animals. Caloric restriction is also known to cause major improvements in a number of markers for cardiovascular diseases in humans. This study is the first to propose that "dietary substitution" can replace "dietary restriction" in a living species.

"If you add glycerol, or restrict caloric intake, you obtain the same effect," said senior author Valter Longo. "It's as good as calorie restriction, yet cells can take it up and utilize it to generate energy or for the synthesis of cellular components."

Longo and colleagues Min Wei and Paola Fabrizio introduced a glycerol diet after discovering that genetically engineered long-lived yeast cells that survive up to 5-fold longer than normal have increased levels of the genes that produce glycerol. In fact, they convert virtually all the glucose and ethanol into glycerol. Notably, these cells have a reduced activity in the TOR1/SCH9 pathway, which is also believed to extend life span in organisms ranging from worms to mice.

When the researchers blocked the genes that produce glycerol, the cells lost most of their life span advantage. However, Longo and colleagues believe that the "glucose to glycerol" switch represents only a component of the protective systems required for the extended survival. The current study indicates that glycerol biosynthesis is an important process in the metabolic switch that allows this simple organism to activate its protective systems and live longer.

"This is a fundamental observation in a very simple system," Longo said, "that at least introduces the possibility that you don't have to be calorie-restricted to achieve some of the remarkable protective effects of the hypocaloric diet observed in many organisms, including humans. It may be sufficient to substitute the carbon source and possibly other macronutrients with nutrients that do not promote the "pro-aging" changes induced by sugars."

Funding for the study came from the American Federation for Aging Research and the National Institute on Aging (NIH).

Tuesday, May 05, 2009

Groundbreaking Study Reveals Intermediary Steps Of Genetic Encoding For The First Time

The scientists report that they were able to crystallize a very large complex of a macromolecular "machine" in the human cell and determine its structure or what it actually looks like, thereby zeroing in on the process of genetic encoding. Importantly, 15 to 20 percent of all human genetic disorders, including muscular dystrophy, are caused by defects in this genetic encoding process known as RNA splicing.

Using x-ray crystallography, the scientists for the first time were able to create a three-dimensional structure of an integral complex of the human spliceosome, which consists of specialized RNA and protein subunits. The spliceosome's job is to modify the message relayed from our genetic material—DNA—by clipping, or splicing, genetic bits in such a manner that they are acceptable for translation into protein. Importantly, the spliceosome also rearranges the genetic bits of the message in such a way that it can generate multiple and varied proteins which can and do have dramatic effects on human development, said lead author and Brandeis biochemist Daniel Pomeranz Krummel.

"The process of RNA splicing is vital to human cell development and survival," said Pomeranz Krummel. "In this process, the regions of our DNA encoding for protein are removed from non-encoding regions and brought together—quite often in alternative arrangements. Defects in this process can have disasterous repercussions in the form of genetic disorders," said Pomeranz Krummel, adding that neuronal development can be particularly affected when things go awry. Indeed, defects in this process have recently been implicated in various human neurological disorders, including epilepsy.

Specifically, this macromolecular machine clips, or splices, gene sequences transcribed as part of a precursor to the mRNA, removing them before the final mRNA product is translated into protein. The spliceosome must clip these sequences, known as introns, at the right place in the precursor mRNA.

"In human cells one gene can be made into a variety of proteins, so if the process just goes slightly wrong, the genetic alteration can lead to incredible disaster; yet on the other hand, this incredible complexity has led to our amazing evolutionary progress," said Pomeranz Krummel. "The human genome is not terribly different from the earthworm's with regards to its size, but the process of RNA splicing that occurs in our cells is different. The fundamental difference between us and the earthworm is that our cells have evolved to utilize this process of RNA splicing to generate a whole other dimension to the transmission of genetic information."

Pomeranz Krummel's lab will next focus on understanding how this complex interacts with other macromolecular machines in the human cell. The study was funded by the Medical Research Council (U.K.) and the Human Frontier Science Program.

Tuesday, April 21, 2009

Did you know?? Omega-3 Kills Cancer Cells

Docosahexanoic acid (DHA), an omega-3 fatty acid found in fish oils, has been shown to reduce the size of tumours and enhance the positive effects of the chemotherapy drug cisplatin, while limiting its harmful side effects. The rat experiments provide some support for the plethora of health benefits often ascribed to omega-3 acids.

DHA is an omega-3 fatty acid that is commonly found in cold-water fish oil, and some vegetable oils. It is a major component of brain gray matter and of the retina in most mammalian species and is considered essential for normal neurological and cellular developments. According to the authors, "While DHA has been tentatively linked with protection against cardiovascular, neurological and neoplastic diseases, there exists a paucity of research information, in particular regarding its interactions with existing chemotherapy drugs". The researchers found that, at the molecular level, DHA acts by reducing leukocytosis (white blood cell accumulation), systemic inflammation, and oxidative stress – all processes that have been linked with tumour growth.

El-Mowafy and his colleagues have called for greater deployment of omega-3 in the fight against cancer. They write, "Our results suggest a new, fruitful drug regimen in the management of solid tumors based on combining cisplatin, and possibly other chemotherapeutics, with DHA".

Monday, April 13, 2009

Human Genes Required For Hepatitis C Viral Replication Identified

Massachusetts General Hospital (MGH) researchers are investigating a new way to block reproduction of the hepatitis C virus (HCV) – targeting not the virus itself but the human genes the virus exploits in its life cycle. In the March 19 Cell Host & Microbe, they report finding nearly 100 genes that support the replication of HCV and show that blocking several of them can suppress viral replication in cultured cells.

"We identified a large number of genes that have not been previously known to be involved in hepatitis C replication," says Raymond Chung, MD, director of Hepatology in the MGH Gastrointestinal Unit, the study's senior author.

Lead author Andrew Tai, MD, PhD, also of the MGH Gastrointestinal Unit, adds, "We may be a few years away from developing therapies based on these findings, but this study is a proof of principle that targeting host factors is a viable therapeutic strategy."

Usually spread by blood-to-blood contact, HCV infection becomes chronic in 70 to 80 percent of patients, and long-term infection can lead to liver failure or liver cancer. Today HCV-related liver disease is the most common diagnosis underlying the need for liver transplantation. HCV infection is usually treated with a six- to eleven-month regimen combining peginterferon and the antiviral drug ribavirin, but treatment is not successful in many patients and has serious side effects some cannot tolerate. Other therapies targeting viral enzymes are being developed, but there is concern that HCV's ability to mutate rapidly would lead to the emergence of resistant strains, so strategies directed against factors in the infected host rather than the virus may offer a complementary approach.

These strategies are being explored in a number of diseases – including influenza, West Nile virus and HIV – and previous studies have scanned a limited number of human genes for host cofactors of HCV infection. For the current study the researchers examined whether blocking each of the approximately 21,000 predicted messenger RNA transcripts in the human genome with small interfering RNAs (siRNAs) had any effect on HCV replication. Chung notes that this approach does not rely on any prior assumptions about gene function and can thereby identify genes not previously suspected of involvement.

The siRNA scan found 96 genes that appear to have a role in viral replication, and the research team studied several of them in greater detail. One gene codes for an enzyme called PI4KA, which is believed to be involved in the formation of membrane structures within the cell that may be the site of HCV replication. Another group of genes contribute to formation of the COPI coat that covers several types of cellular vesicles and is known to have a role in the replication of poliovirus. The researchers also focused on the gene for hepcidin, a liver protein that regulates iron absorption, since iron levels in the blood and liver rise in chronic HCV infection. They found that blocking each of these genes also blocked HCV replication, as did drugs that inhibit PI4KA and COPI, although the tested agents might not be suitable for therapeutic use.

"Now we need to work to uncover the molecular mechanisms by which these genes support HCV replication to get a better idea of which would be advantageous therapeutic targets," explains Chung, an associate professor of Medicine at Harvard Medical School.

Additional co-authors of the Cell Host & Microbe paper are Yair Benita, PhD, Sun-Suk Kim, MD, and Ramnik Xavier, MB,ChB, MGH Gastrointestinal Unit; and Naoya Sakamoto, MD, PhD,Tokyo Medical and Dental University. The study was supported by grants from the National Institutes of Health, the Massachusetts Biomedical Research Corporation, the American Gastrointestinal Association and the American Liver Foundation.

Newly Identified Protein May Inhibit Hepatitis Virus

A newly identified family of proteins may inhibit replication of the
Hepatitis B (HBV) and C (HCV) viruses say researchers from California.
Their findings appear in the March 2005 issue of the Journal of
Virology.Hepatitis B (HBV) and C (HCV) are viruses that infect the liver, and in some cases can cause liver failure requiring a transplant for survival. The protein interferon, produced by animal cells when they are invaded by viruses, is released into the bloodstream or intercellular fluid to induce healthy cells to manufacture an enzyme that counters the infection. One class of interferons (alpha) is used to treat chronic infection with HBV and HCV. There is a vaccine available to prevent the spread of HBV but not HCV.

In the study, a new class of interferons, interferon lambda, was tested for its ability to inhibit HBV and HCV replication. Results showed 90% inhibition of HBV after twenty-four hours and 90-99% inhibition in HCV five days posttreatment.

“We have demonstrated here that replication of HBV and HCV is sensitive to the antiviral activities of interferon lambda,” say the researchers. “These results suggest the possibility that interferon lambda may be therapeutically useful in the treatment of chronic HBV or HCV infection.”

(M.D. Robek, B.S. Boyd, F.V. Chisari. 2005. Lambda interferon inhibits hepatitis B and C virus replication. Journal of Virology, 79. 6: 3851-3854.)

Saturday, April 04, 2009

Mutated Gene In Zebrafish Sheds Light On Blindness In Humans

Described in a paper published in the Proceedings of the National Academy of Sciences (PNAS), the landmark study of retinal development in zebrafish larvae and the genetic switch it has identified should shed new light on the molecular mechanisms underlying that development and, consequently, provide needed insight on inherited retinal diseases in humans.

From FSU's Department of Biological Science and Program in Neuroscience, doctoral candidate Karen Alvarez-Delfin (first author of the PNAS paper), postdoctoral fellow Ann Morris (second author), and Associate Professor James M. Fadool are the first scientists to identify the crucial function of a previously known gene called "tbx2b." The researchers have named the newfound allele (a different form of a gene) "lor" -- for "lots-of-rods" -- because the mutation results in too many rods and fewer ultraviolet cones than in the normal eye.

"Our goal is to generate animal models of inherited diseases of the eye and retina to understand the progression of disease and find more effective treatments for blindness," said Fadool, faculty advisor to Alvarez-Delfin and principal investigator for Morris's ongoing research. "We are excited about the mutation that Karen has identified because it is one of the few mutations in this clinically critical pathway that is responsible for cells developing into one photoreceptor subtype rather than another."

"What is striking in this case is that the photoreceptor cell changes we observed in the retinas of zebrafish are opposite to the changes identified in Enhanced S-cone syndrome (ESCS), an inherited human retinal dystrophy in which the rods express genes usually only found in cones, eventually leading to blindness," Alvarez-Delfin said. "Equally surprising is that this study and others from our lab show that while alterations in photoreceptor development in the human and mouse eyes lead to retinal degeneration and blindness, they don't in zebrafish. Therefore, the work from our Florida State lab and with our collaborators at the University of Pennsylvania, Vanderbilt University and the University of Louisville should provide a model for better understanding the differences in outcomes between mammals and fish, and why the human mutation leads to degenerative disease."

Morris calls the zebrafish an ideal genetic model for studies of development and disease. The common aquarium species are vertebrates, like humans. Their retinal organization and cell types are similar to those in humans. Zebrafish mature rapidly, and lay many eggs. The embryos are transparent, and they develop externally, unlike mammals, which develop in utero.

"This lets us study developmental processes such as the formation of tissues and organs in living animals," she said.

"From a developmental biology perspective, our research will help us unravel the competing signals necessary for generating the different photoreceptor cell types in their appropriate numbers and arrangement," Morris said. "The highly specialized nature of rods and cones may make them particularly vulnerable to inherited diseases and environmental damage in humans. Understanding the genetic processes of photoreceptor development could lead to clinical treatments for the millions of people affected by photoreceptor cell dystrophies such as retinitis pigmentosa and macular degeneration."

The mosaic arrangement of photoreceptors in fish was first described more than 100 years ago, but the J. Fadool laboratory at Florida State was the first to successfully take advantage of the pattern to identify mutations affecting photoreceptor development and degeneration.

"Imagine a tile mosaic," Fadool said. "That is the kind of geometric pattern formed by the rod and cone photoreceptors in the zebrafish retina. This mosaic is similar to the pattern of a checkerboard but with four colors rather than two alternating in a square pattern. The red-, green-, blue-, and ultraviolet-sensitive cones are always arranged in a precise repeating pattern. Human retinas have a photoreceptor mosaic, too, but here the term is used loosely, because while the arrangement of the different photoreceptors is nonrandom, they don't form the geometric pattern observed in zebrafish.

"So how do we ask a fish if it has photoreceptor defects?" he asked.

Fadool explained that because the mosaic pattern of zebrafish photoreceptors is so precise, mutations causing subtle alterations are easier to uncover than in retinas with a "messier" arrangement.

"Just as we can easily recognize a checkerboard mistakenly manufactured with some of the squares changed from black to red or with all-black squares, by using fluorescent labeling and fluorescence microscopes we can see similar changes in the pattern of the zebrafish photoreceptor mosaic," he said. "Karen showed that within the mosaic of the lots-of-rod fish, the position on the checkerboard normally occupied by a UV cone is replaced with a rod. The identity of the mutated gene is then discovered using a combination of classical genetics and genomic resources."

Funding for the Fadool laboratory's zebrafish research comes in large part from a five-year grant totaling more than $1.7 million from the National Institutes of Health.

Wednesday, April 01, 2009

Rejoice Fatboys!! Fitness More Than Fatness Determines Your Health and Longevity

Did you know that fitness level is a strong predictor of longevity, especially for adults over age 60? While obesity receives much airtime as a public health problem, it seems that being thin is not the be-all and end-all of a healthy body.

Results of a 12-year study have indicated that fitness levels can be more important than your weight levels and can definitely influence whether or not you suffer from health problems and die earlier than those who are physically fit but not necessarily thin.

The 12-year study was conducted by Professor Steven Blair from the University of South Carolina in Columbia. Researchers looked at the relationship between body fat, fitness and longevity in 2,603 people over the age of 60.

At the start of the study, fitness levels were assessed using a treadmill stress test and body fat was calculated by various measures, including BMI, waist circumference and fat percentages. The volunteers had follow-up medical checks over the 12-year study period.

The overall results showed that fit adults who engage in cardiovascular exercise on a regular basis outlived the unfit, regardless of their level of obesity or waist size. There were 450 deaths during the study. Researchers found that those who died were older, had lower fitness levels and had more cardiovascular risk factors than survivors.

Death rates for those with higher fitness levels were less than half of the rates for those who were unfit and not surprisingly they were less likely to have risk factors for cardiovascular disease, such as hypertension, diabetes, or high cholesterol levels. The exception however was with those who were severely obese or with large amounts of abdominal fat.

The message from these study results is that there is great benefit to being physically active on a regular basis even if you are overweight. Exercise has a systematic effect on many levels - it strengthens the heart, the lungs and builds up the skeletal muscles. It also provides great benefit to the brain and the overall well-being of the person. It is important though to maintain a healthy body weight at the same time.

"Our data provides further evidence regarding the complex long-term relationship among fitness, body size and survival. It may be possible to reduce all-cause death rates among older adults, including those who are obese, by promoting regular physical activity, such as brisk walking for 30 minutes or more on most days of the week," said Dr. Xuemei Sui of the University of South Carolina.

Sunday, March 22, 2009

Gene Therapy Demonstrates Benefit In Patients With Rheumatoid Arthritis

Researchers have reported the first clinical evidence that gene therapy reduces symptoms in patients with rheumatoid arthritis, an important milestone for this promising treatment which has endured a sometimes turbulent past.

Described in the February issue of the journal Human Gene Therapy the findings stem from a study of two patients with severe rheumatoid arthritis conducted in Germany and led by an investigator at Beth Israel Deaconess Medical Center (BIDMC).

Originally conceived as a means of treating genetic diseases, such as cystic fibrosis and hemophilia, gene therapy involves implanting a normal gene to compensate for a defective gene in the patient. The first clinical trial to test gene therapy was launched in 1990 for the treatment of a rare, genetic immunodeficiency disease.

"This study helps extend gene therapy research to nongenetic, nonlethal diseases," explains principal investigator Christopher Evans, PhD, Director of the Center for Advanced Orthopaedic Studies at BIDMC. "Rheumatoid arthritis [RA] is an extremely painful condition affecting multiple joints throughout the body. Arthritis is a good target for this treatment because the joint is a closed space into which we can inject genes," adds Evans, who is also the Maurice Muller Professor of Orthopaedic Surgery at Harvard Medical School.

A classic autoimmune disease, RA develops when, for unknown reasons, the body's immune system turns against itself, causing joints to become swollen and inflamed. If the disease is inadequately controlled, the tissues of the joint are eventually destroyed. Although anti-inflammatory agents and biologics can help to mitigate symptoms, there is no cure for the condition, estimated to affect more than 2 million individuals in the U.S. alone.

Evans has spent many years studying the molecules responsible for the breakdown of cartilage in patients with arthritis, identifying interleukin-1 as a good target. But, he adds, once he had this answer, another question was not far behind: How could he effectively reach the joints to block the actions of this protein?

Gene therapy provided the answer.

By implanting a gene in the affected joint, he was able to stimulate production of a human interleukin-1 receptor antagonist protein, which serves to block actions of the interleukin-1 protein.

"The idea is that by remaining in place, the new gene can continuously block the action of the interleukin-1 within the joints," says Evans. "In essence, the gene becomes its own little factory, continuously working to alleviate pain and swelling."

In 2005, in a study published in the Proceedings of the National Academy of Sciences (PNAS), Evans and colleagues demonstrated that the IL-1Ra gene could be safely transferred to human joints in patients with RA. In this new paper, the authors aimed to prove that the therapy was not only safe, but that it was of therapeutic benefit.

Two study subjects were recruited. (The number reduced from six study subjects following severe adverse events in an unrelated gene therapy trial taking place elsewhere, according to Evans.) Both subjects were postmenopausal females under the age of 75 with a diagnosis of advanced rheumatoid arthritis. After tissue was removed from the subjects' knuckle joints, a harmless retrovirus was inserted into the tissue cells, in order to serve as a "vector" to transport the gene into the patients' joints. After being placed in culture to grow and replicate, the cells were injected back into the afflicted joints.

After four weeks, patients reported reduced pain and swelling, according to Evans. "In one of the two subjects, these effects were dramatic, and the gene-treated joints remained pain-free even though other joints experience flares." Subsequent laboratory tests showed that tissues removed from the subject's joint tissue synthesized lower amounts of disease-related proteins, confirming that the reduction in pain and swelling resulted from the actions of the implanted gene.

"Existing treatments for rheumatoid arthritis are costly and need to be administered regularly," says Evans, adding that in addition to risk of side effects, not all patients respond well. "This paper provides us with the first real evidence that painful symptoms can indeed be lessened through gene therapy."

Ongoing work will focus on the use of gene therapy for the treatment of osteoarthritis, as well as rheumatoid arthritis.

This study was funded, in part, by grants from the National Institutes of Health and Orthogen, a German biotechnology company.

Study coauthors include Peter Wehling, Julio Reinecke, Axel Baltzer, Marcus Granrath, Klaus Schulitz, Carl Schultz, and Rudiger Krauspe of the University of Dusseldorf School of Medicine, Germany; Theresa Whiteside, Elaine Elder and Paul Robbins of the University of Pittsburgh School of Medicine; and Steven Ghivizzani of the University of Florida College of Medicine.

Saturday, March 14, 2009

Is There A Relationship Between Sleep-wake Rhythm And Diabetes?

An international research team with German participation including Helmholtz Zentrum München, among other institutions, has succeeded in identifying a new gene variant which is associated with elevated fasting glucose levels and a high risk for type 2 diabetes. The gene mediates insulin secretion indirectly via the release of melatonin, which implicates a previously unknown relationship between the sleep-wake rhythm and the fasting glucose level. The finding could open up new possibilities of treatment which go far beyond the primarily symptomatic therapy approaches to diabetes that have been practised until now.

Diabetes mellitus and diabetes-associated late complications are among the most frequent chronic diseases and causes of death worldwide. In Germany there are approximately six million people with type 2 diabetes who are aware that they have the disease. In addition, there is a relatively high estimated number of undiagnosed diabetics. Besides lifestyle factors such as overweight and lack of exercise, genetic factors play an important role in the pathogenesis of this disease.

The international MAGIC Consortium (MAGIC = Meta-Analyses of Glucose and Insulin-related traits Consortium) combined the data from 13 case-control studies with over 18,000 diabetic and 64,000 non-diabetic study participants and was able to identify a variant of the MTNR1B gene which is associated with both elevated fasting glucose levels as well an elevated risk for type 2 diabetes. The goal of the MAGIC Consortium is to identify gene variants which regulate the fasting glucose levels in healthy individuals.

Germany is represented within the framework of the KORA studies by scientists of the Helmholtz Zentrum München (Assistant Professor Thomas Illig; Director of the KORA studies: Professor H.-Erich Wichmann) and the German Diabetes Center in Düsseldorf (Dr. Wolfgang Rathmann, Dr. Christian Herder; Direktor: Professor Michael Roden).

The MTNR1B gene is expressed in insulin-producing islet cells, among other cells, and encodes one of the two known melatonin receptors. It is assumed that this receptor inhibits the release of insulin via the neural hormone melatonin. The melatonin level in the body is high at night and declines in daylight, whereas the insulin level is higher during the day than in the night. Taken together, these new data implicate an association between the sleep-wake rhythm, the so-called circadian rhythm, and fasting glucose levels, which was not known previously.

Until now an efficient strategy for prevention and for therapies to treat the cause of the disease has been missing in diabetes research. The Helmholtz Zentrum München is working intensively on new approaches in the study and treatment of diabetes. Further studies will show which role melatonin plays in the regulation of insulin secretion, fasting glucose levels and the development of diabetes and whether this finding will lead to new treatment options.

Sunday, March 08, 2009

Target That Could Ease Spinal Muscular Atrophy Symptoms Discovered

There is no cure for spinal muscular atrophy (SMA), a genetic disorder that causes the weakening of muscles and is the leading genetic cause of infant death, but University of Missouri researchers have discovered a new therapeutic target that improves deteriorating skeletal muscle tissue caused by SMA. The new therapy enhanced muscle strength, improved gross motor skills and increased the lifespan in a SMA model.

“This therapy does not directly target the disease-causing gene; instead it targets the pathways that affect muscle maintenance and growth,” said Chris Lorson, investigator in the Christopher S. Bond Life Sciences Center and associate professor of veterinary pathobiology in the MU College of Veterinary Medicine. “We administered a particular protein, follistatin, to SMA mouse models to determine if enhanced muscle mass impacts the symptoms of SMA. After treatment, the mice had increased muscle mass, gross motor function improvement and an increase in average life span of 30 percent.”

 With the therapy, MU researchers inhibited myostatin, a protein that limits muscle tissue growth. Myostatin activity can be reduced significantly by enabling several proteins that bind to myostatin, including follistatin. When myostatin is inhibited, muscle mass and strength increase.

SMA is caused by the loss of survival motor neuron-1(SMN1). Humans have a nearly identical copy gene called SMN2. Because of a single molecular difference, SMN2 alone cannot compensate for the loss of SMN1.

“While most work in the SMA field has logically focused on targeting the SMN2 gene, the results of this study suggest that skeletal muscle is a viable therapeutic target that may reduce the severity of some SMA symptoms,” said Lorson, who also is the scientific director for FightSMA, a private spinal muscular atrophy research foundation in Richmond, Va. “Because follistatin does not alter the expression level of SMN protein, the most effective treatment would combine strategies that directly address the genetic defect in SMA as well as SMN-independent strategies that enhance skeletal muscle.”

In Jan 2009, Lorson was awarded a $370,000 grant from the Muscular Dystrophy Association to continue his research on the role of muscle in SMA.

Monday, March 02, 2009

Gene Abnormality Found To Predict Childhood Leukemia Relapse

Scientists have identified mutations in a gene that predict a high likelihood of relapse in children with acute lymphoblastic leukemia (ALL). Although the researchers caution that further research is needed to determine how changes in the gene, called IKZF1 or IKAROS, lead to leukemia relapse, the findings are likely to provide the basis for future diagnostic tests to assess the risk of treatment failure. By using a molecular test to identify this genetic marker in ALL patients, physicians should be better able to assign patients to appropriate therapies.

The findings of the Children's Oncology Group (COG) study, led by scientists from St. Jude Children's Research Hospital, Memphis, Tenn., the University of New Mexico Cancer Research and Treatment Center, Albuquerque, N.M., and the National Cancer Institute (NCI), part of the National Institutes of Health, appear online Jan.7, 2009, in the New England Journal of Medicine, and in print on Jan. 29, 2009.

ALL, a cancer of the white blood cells, is the most common childhood cancer, in that it affects about one in 29,000 children annually. Using currently available therapies, cure rates for ALL are now upwards of 80 percent. However, those therapies carry with them substantial side effects, and even with treatment, only 30 percent of children who experience a relapse of ALL will survive five years. Determining the risk of relapse faced by an individual patient would help physicians tailor treatment intensity appropriately, but until now there has been no good marker for predicting outcome.

"Great progress has been made in recent years in improving the cure rate of childhood ALL," said Stephen Hunger, M.D., chairman of the COG ALL committee and the lead COG investigator on this study. "The findings of this study help us further subdivide those patients who are unlikely to be cured, and identify patients in whom different therapies should be tested."

In the study, researchers analyzed genetic data on leukemia cells obtained at diagnosis from 221 children with high-risk leukemia (i.e. a high chance of relapse) who had been treated in an existing COG study. They conducted their analysis using microarrays and DNA sequencing – technologies which allow researchers to quickly and efficiently identify and analyze multiple genes simultaneously in the same cell. Using these technologies to identify genetic abnormalities in leukemia cells, the investigators examined the DNA of the leukemia cells at the time of diagnosis and then determined if any of the identified genetic changes predicted relapse. To confirm that specific genetic changes were associated with relapse, the scientists also examined a second group of 258 children with ALL who were treated at St. Jude.

"We looked across the genome in an unbiased fashion in an attempt to pull out any genes that were significantly associated with outcome," said Charles Mullighan, M.D., Ph.D., assistant member in the St. Jude Department of Pathology and the paper's first author. "From these findings, we identified a group of genetic abnormalities that together predicted poor outcome."

The most significant association was with the deletions or changes in the IKAROS gene. Mutations of IKAROS were shown to identify a subgroup of patients who were treated in the COG study that had a very poor prognosis. The prognostic significance of these genetic alterations was validated in the independent St. Jude patient group, a finding of particular importance since different types of therapies were used in these two groups of patients.

Previous research has shown that the IKAROS gene serves as the blueprint for the production of the IKAROS protein, which regulates the activity of many other genes. The IKAROS protein plays an essential role in the development of lymphocytes, the white blood cells that, when changed, give rise to pediatric ALL. The way in which IKAROS abnormalities contribute to the development of relapse remains to be determined.

The study also examined gene expression in the leukemia cells using microarray chips, and found that leukemia cells from patients with IKAROS alterations expressed primitive, stem cell-like genes, suggesting that the cells are less mature and possibly more resistant to the effects of drugs used to treat ALL. "These findings show how detailed analysis of leukemic cells using complementary techniques can enhance our understanding of the genetic basis of leukemia," said co-author Cheryl Willman, director and CEO, University of New Mexico Cancer Research and Treatment Center.

The researchers also tested whether the presence of IKAROS alterations was associated with levels of minimal residual disease, another measure of treatment response in ALL.

"Measurement of levels of minimal residual disease is widely used to monitor treatment responsiveness and also to alter patients' therapy if they have a very poor response to treatment," said James Downing, M.D., St. Jude scientific director and the paper's senior author. "An important analysis we conducted was to see whether identifying the association of IKAROS alterations with poor outcome added anything to just measuring levels of minimal residual disease. And, indeed, it did."

The researchers' analysis indicated that identifying IKAROS alterations may be clinically useful and will complement existing diagnostic tests and measurement of minimal residual disease levels.

While a clinical test for alterations of IKAROS could prove valuable for predicting poor outcomes in children with ALL, complexities remain. There are different types of deletions in the gene, some that involve the entire IKAROS gene and others that involve only parts of the gene. Because the genetic alterations in IKAROS in ALL are not uniform or limited to a single mutation or deletion, it may be necessary to develop a panel of different tests to detect IKAROS lesions and identify which patients are at highest risk for relapse.

This research was done as part of the NCI Therapeutically Applicable Research to Generate Effective Treatments (TARGET) initiative, which seeks to utilize the study of genomics to identify therapeutic targets in order to develop more effective treatments for childhood cancers. The first two cancers being studied in the program are ALL and neuroblastoma, a cancer that arises in immature nerve cells and affects mostly infants and children. Combined, these two cancers account for 3,000 new cases each year, and in both cancers, there are some children who have a very favorable prognosis and others who are at high risk for treatment failure. By determining the genetic factors that distinguish these groups, the hope is that researchers can use this information to improve patient outcomes and develop better treatments, particularly for those in the high-risk group.

"In the long term, our goal is to develop effective therapeutic interventions, directed toward vulnerabilities that leukemia cells acquire as a result of the genomic abnormalities identified through the TARGET initiative," said Malcolm Smith, M.D., Ph.D., of NCI's Cancer Therapy Evaluation Program.

Monday, February 23, 2009

Earlier Diagnosis Of Uterine Cancer Possible With New Findings

Cancer of the uterus (womb) is the commonest gynaecological malignancy in the West. Research carried out at the University of Gothenburg, Sweden, has now identified a gene that may simplify future diagnosis.

Cancer is a genetic disease. It occurs when changes take place in the genes that regulate cell division, cell growth, cell death, cell signalling and blood vessel formation – either due to mutations caused by external factors such as smoking or radiation – or due to inherited changes. This interaction between defective genes and environmental factors means that cancer is an extremely complex disease. Cancer of the uterus, or endometrial carcinoma, is no exception.

Cancer of the uterus is the commonest gynaecological malignancy in the West and accounts for between five and six per cent of all cancers in Swedish women. However, the symptoms are often vague, and we know little about the genetic factors that lead to the appearance and development of this form of cancer. It is therefore vital that these genes are identified, as this could enable doctors to make the diagnosis much more quickly and easily, allowing the development of more effective cancer treatment.

In her study, Sandra Karlsson, a researcher at the Department of Cell and Molecular Biology, has used inbred rats to locate the defective genes that cause uterine cancer. Like monozygotic (identical) twins, these inbred rats are genetically almost identical, which makes it much easier to study the influence of the environment in which they live.

“More than 90 per cent of the female rats in the study spontaneously developed uterine cancer. By using advanced techniques to analyse gene expression in the tumours, we succeeded in identifying a gene signature that could be used as a future diagnostic test for human uterine cancer,” says Sandra Karlsson.

The signature is made up of three genes. One of them protects the cell against oxygen free radicals. These free radicals are naturally and continuously produced in the cell, but excess amounts, which can damage the cell and the body’s DNA, are associated with over 200 diseases, from arteriosclerosis and dementia to rheumatism, cerebral haemorrhage and cancer. The studies carried out by Sandra Karlsson on human malignant tumours have confirmed that changes in this gene are present in early as well as late stage cancer.

“This shows that the identified gene has an important role in the origin and development of uterine cancer,” says Sandra Karlsson.

The thesis Gene Expression Patterns in a Rat Model of Human Endometrial Adenocarcinoma was publicly defended on the December 19th. Supervisor – Professor Karin Klinga Levan.

Monday, February 16, 2009

Shortened DATE Gene Region Linked To Breast Cancer

Reza Zarnegar and colleagues, at the University of Pittsburgh, Pittsburgh, have determined that genetic variation in a piece of DNA that regulates activity of the HGF gene might be a useful marker to identify individuals with an increased risk of developing breast cancer.

The HGF gene is not active in normal breast epithelial cells. However, its activity is not repressed in tumor samples from many patients with breast cancer. In the study, the authors identified a DNA region that controls the activity of the HGF gene and named it DATE (deoxyadenosine tract element).

Functional studies determined that shortening the DATE region led to activation of the HGF gene in cell lines. Further analysis indicated that a substantial proportion of patients with breast cancer have shortened DATE regions, and that these patients were markedly younger than patients with a DATE region of normal length.

Given these data, the authors suggest that future studies should investigate whether shortened DATE regions are also associated with other cancers that overexpress HGF, such as some forms of colon, stomach, pancreatic, endometrial, and cervical cancer.

Tuesday, February 10, 2009

Gene Therapy For Blindness Improves Vision, Safety Study Indicates

All three people who received gene therapy at the University of Florida to treat a rare, incurable form of blindness have regained some of their vision, according to a paper published online today in Human Gene Therapy. The patients — one woman and two men ranging from 21 to 24 years old with a type of hereditary blindness called Leber congenital amaurosis type 2 — volunteered to test the safety of an experimental gene-transfer technique in a phase 1 clinical research study conducted by UF and the University of Pennsylvania with support from the National Eye Institute of the National Institutes of Health.

In this form of LCA disease, photoreceptor cells cannot respond to light because a gene called RPE65 does not properly produce a protein necessary for healthy vision. In the study, researchers used an adeno-associated virus — an apparently harmless virus that already exists in most people — to deliver RPE65 to a small area of the retina.

Not only were there no ill effects other than routine postsurgical soreness, the subjects said the vision in their treated eyes was slightly improved in dim lighting conditions.

"The patients report seeing brighter areas and perhaps some images, but basically the message is that this is treatment is fully safe," said William W. Hauswirth, Ph.D., a professor of ophthalmology and member of UF's Powell Gene Therapy Center and the UF Genetics Institute.

"One thing we did not do is suppress the patients' immune systems, which was done in two other LCA clinical trials that were under way," said Hauswirth, who began studying the adeno-associated virus as a vehicle to deliver genes into living animals more than 30 years ago. "Theoretically, the idea was that it might be necessary to suppress the immune system because we are using a vector that might activate the body's defenses and cause a harmful response. However, immune suppression itself carries a risk of infections and other problems. Clearly we have shown there is no need to do that in this case."

Samuel G. Jacobson, M.D., Ph.D., a professor of ophthalmology with the Scheie Eye Institute at the University of Pennsylvania, is the study's principal investigator.

"This groundbreaking gene therapy trial builds on 15 years of research sponsored by the National Eye Institute of NIH," said Paul A. Sieving, M.D., Ph.D., director of the NEI. "The study has partially restored vision in three young adults, and it demonstrates that gene therapy can be effective in treating human vision disease. Many human diseases are inherited in families and result from mutations in single genes. These genetic conditions are particularly suited to potential treatment by gene therapy. This trial to treat vision loss from the condition of Leber congenital amaurosis is an important demonstration of proof of principle and shows that we are on the right track. We can now invest in further work to refine, and ultimately to expand, genetic treatment approaches."

Results published today focus on the health of the entire retina, not just the tiny portion that received the gene therapy. A detailed examination of the therapy's effectiveness in the treated portion of the eye will appear in an upcoming issue of the Proceedings of the National Academy of Sciences. Two other recent LCA clinical trial reports appeared recently in The New England Journal of Medicine.

"The safety study itself is a milestone, but when we see a benefit to the subject — that is a truly a welcome bonus," said Barry J. Byrne, M.D., Ph.D., a professor of molecular genetics and microbiology and director of UF's Powell Gene Therapy Center, which manufactured the viral vectors used in the study. "Improvements in someone's medical condition are ultimately what we are after."

LCA2 affects about 2,000 people in the United States and is one of several incurable forms of blindness collectively known as retinitis pigmentosa, which in turn affects about 200,000 Americans.

Children with LCA2 experience major visual disability that can lead to total vision loss in adulthood. Although vision loss is severe, the structure of the retina — including its connection to the brain — can remain relatively intact for decades before the photoreceptor cells degenerate.

Sunday, February 08, 2009

Numerous Undiscovered Gene Alterations In Pancreatic And Brain Cancers Detected

HHMI investigators have detected a multitude of broken, missing, and overactive genes in pancreatic and brain tumors, in the most detailed genetic survey yet of any human tumor. Some of these genetic changes were previously unknown and could provide new leads for improved diagnosis and therapy for these devastating cancers.

The discoveries, described in two reports published September 4, 2008, in Science Express, which provides early electronic publication of selected Science papers, emerged from the sequencing of nearly all the known protein-making genes in pancreatic cancers and in the most common form of brain tumors, glioblastomas. The study adds numerous items to the known "parts list" of these cancers, though further research is needed to determine which gene changes actually trigger development or spread of the disease.

HHMI investigator Bert Vogelstein and colleagues at the Johns Hopkins Kimmel Cancer Center, in collaboration with investigators at Duke University and elsewhere, sequenced 20,661 genes in cells from 24 patients with pancreatic cancer and 22 patients with glioblastoma. The team identified hundreds of gene mutations associated with the cancers.

The researchers also found numerous cases where tumor cells had extra or too few copies of a gene. The typical pancreatic cancer contained 63 genetic alterations, while the average brain tumor contained 60. Using "next generation" sequencing, the researchers also comprehensively assessed changes in levels of gene activity.

Taken together, the two studies suggest that a small number of commonly mutated genes - or "mountains" - and a much larger number of rarer, low-frequency gene changes - "hills" - cause these cancers, said the researchers.

The authors said their results demonstrate that "genome-wide genetic analyses…can identify the precise genetic alterations that are likely to be responsible for pathway disregulation in each patient's tumor." They found that each individual tumor had its own particular assortment of gene changes. "If you have 100 patients, you have 100 different diseases," said Vogelstein, who is a co-corresponding author of the Science paper with Johns Hopkins researchers Victor E. Velculescu and Kenneth W. Kinzler. "But this will not surprise clinical oncologists, because they see how different every patient is" in the way their tumor behaves and responds to treatment.

Cancer biologist Tyler Jacks, a Howard Hughes Medical Institute investigator at the Massachusetts Institute of Technology who was not involved in the studies, said he was not surprised by the large number of infrequent gene mutations — primarily because Vogelstein and his colleagues reported in 2007 that they had found breast and colon cancers to be similarly complex genetically. "But if you had asked me three years ago, I would have given a different answer," Jacks said.

Vogelstein said the sheer number and variability of genetic changes in the tumors pose a challenge to one of the main goals of "personalized medicine" — identifying as many cancer-causing mutations as possible and developing an array of targeted drugs, each designed to strike a specific mutation.

Jacks agreed that cancer researchers would have preferred that tumors' mutational landscapes be dominated by the high-frequency "mountains," as these make attractive targets for the design of new drugs. With conventional DNA sequencing technologies, these prominent mountains were the mutations most readily linked to cancer, he said. But as new methods make it feasible to sequence nearly all the genes in a tumor sample, researchers are beginning to recognize that "the landscape is crowded with changes, mostly occurring at low frequency."

"It's suggesting that maybe we shouldn't even be focusing so much on the individual genes that are mutated," Vogelstein said. "Instead, we should be thinking about the functional pathways in which these genes operate. This is a different way of looking at how cancer develops."

Indeed, many of the gene abnormalities could be grouped into functional units. For example, when they analyzed the DNA in 24 pancreatic cancers, the scientists identified 12 core signaling pathways that were each abnormal in the great majority of tumors. Some of those pathways regulate apoptosis - the programmed death of abnormal cells - or repair of damaged DNA. Other altered pathways control the rate of cell division, influence how tightly cells stick together, or determine their ability to invade nearby tissues.

In the brain tumor samples, the survey found that the mutated genes could be grouped into similar pathways, such as those controlling growth and apoptosis. However, some of the newly found mutations occurred in pathways involved in nervous system signaling processes not previously known to be altered in any form of cancer. The scientists speculate that this pathway may be specific for glial cell tumorigenesis.

Similarly, one particular genetic change netted by the survey was found exclusively in brain tumors. That mutation was particularly intriguing because of its potential near-term clinical importance. Specific mutations in the isocitrate dehydrogenase gene IDH1 were found in 12 percent of the brain tumors. They were found in almost all cases of secondary glioblastomas - developing from lower-grade tumors - but rarely in primary high-grade glioblastomas. They also tended to affect younger patients (average age 33 compared to age 53 for patients without the mutations). Patients whose brain tumors had the IDH1mutation lived significantly longer with their cancer than those who did not.

Although it is not known how the IDH1 mutation contributes to cancer, Vogelstein said that it could help single out individuals who are likely to have better outcomes. With further research, it is conceivable that the mutation could have relevance for therapy, he said.

Like the Vogelstein group's 2007 findings on breast and colon cancer, the new study suggests that many these diseases are caused not by a few major genetic kingpins, but instead by a large cast of minor culprits. How this multiplicity of cancer triggers can best be confronted is uncertain, but the authors of the two papers say it may force a shift in drug development emphasis. The best hope for new therapies, they wrote, "may lie in the discovery of agents that target the physiologic effects of the altered pathways and processes, rather than their individual genetic components."

Friday, February 06, 2009

For Fats, Longer May Not Be Better

Researchers have uncovered why some dietary fats, specifically long-chain fats, such as oleic acid (found in olive oil), are more prone to induce inflammation. Long-chain fats, it turns out, promote increased intestinal absorption of pro-inflammatory bacterial molecules called lipopolysaccharides (LPS).

While dietary fats that have short chains (such as those found in milk and cheese products) can be absorbed directly into the bloodstream from the intestines, long-chain fats need to be first packaged by the intestinal cells into particles known as chylomicrons (large complexes similar to HDL and LDL particles). Erik Eckhardt and colleagues at the University of Kentucky wondered whether some unwanted LPS particles, routinely shed by the bacteria that inhabit the human gut, might also be sneaking in the chylomicrons.

Their hypothesis turned out to be correct; when they treated cultured human intestinal cells with oleic acid they observed significant secretion of LPS together with the chylomicron particles, a phenomenon that was not observed when the cells were treated with short-chain butyric acid. Similar findings were found in mouse studies; high amounts of dietary oleic acid, but not butyric acid, promoted significant absorption of LPS into the blood and lymph nodes and subsequent expression of inflammatory genes.

Eckhardt and colleagues believe these findings may pave the way for future therapies for Crohn's disease and other inflammatory bowel disorders. In addition, they note that this study once again highlights the importance of the diverse bacteria that call our intestines home.

Treatment For Hearing Loss? Scientists Grow Hair Cells Involved in Hearing

Oregon Health & Science University scientists have successfully produced functional auditory hair cells in the cochlea of the mouse inner ear. The breakthrough suggests that a new therapy may be developed in the future to successfully treat hearing loss. The results of this research was recently published by the journal Nature.   

“One approach to restore auditory function is to replace defective cells with healthy new cells,” said John Brigande, Ph.D., an assistant professor of otolaryngology at the Oregon Hearing Research Center in the OHSU School of Medicine. “Our work shows that it is possible to produce functional auditory hair cells in the mammalian cochlea.”

The researchers specifically focused on the tiny hair cells located in a portion of the ear’s cochlea called the organ of Corti. It has long been understood that as these hair cells die, hearing loss occurs. Throughout a person’s life, a certain number of these cells malfunction or die naturally leading to gradual hearing loss often witnessed in aging persons. Those who are exposed to loud noises for a prolonged period or suffer from certain diseases lose more sensory hair cells than average and therefore suffer from more pronounced hearing loss.

Brigande and his colleagues were able to produce hair cells by transferring a key gene, called Atoh1, into the developing inner ears of mice. The gene was inserted along with green florescent protein (GFP) which is the molecule that makes a species of jellyfish glow. GFP is often used in research as a “marker” that a scientist can use to determine, in this case, the exact location of the Atoh1 expression.  Remarkably, the gene transfer technique resulted in Atoh1 expression in the organ of Corti, where the sensory hair cells form.

Using this method, the researchers were able to trace how the inserted genetic material successfully led to hair cell production resulting in the appearance of more hair cells than are typically located in the ears of early postnatal mice. Crucially, Dr. Anthony Ricci, associate professor of otolaryngology at the Stanford University School of Medicine, demonstrated that the hair cells have electrophysiological properties consistent with wild type or endogenous hair cells, meaning that the hair cells appear to be functional. Based on these data, the scientists concluded that Atoh1 expression generates functional auditory hair cells in the inner ear of newborn mammals.

“It remains to be determined whether gene transfer into a deaf mouse will lead to the production of healthy cells that enable hearing. However, we have made an important step toward defining an approach that may lead to therapeutic intervention for hearing loss,” Brigande said.

Tuesday, February 03, 2009

Key Component In Cell Replication Identified

Last week, a presidential limousine shuttled Barack Obama to the most important job in his life. Scientists at the Stanford University School of Medicine have now identified a protein that does much the same for the telomerase enzyme — ferrying the critically important clump of proteins around to repair the ends of chromosomes that are lost during normal replication. Without such ongoing maintenance, stem cells would soon cease dividing and embryos would fail to develop.

"This is the first new protein component of telomerase that has been identified in 10 years," said Steven Artandi, MD, PhD, associate professor of hematology. "And it's likely to be a valuable target for anti-cancer therapies."

Artandi is the senior author of the research, which will be published in the Jan. 30 issue of Science. Graduate student Andrew Venteicher is the first author. The two collaborated with scientists at the National Cancer Institute-Frederick and the University of Georgia to conduct the research.

Telomerase is normally expressed in adult stem cells and immune cells, as well as in cells of the developing embryo. In these cells, the enzyme caps off the ends of newly replicated chromosomes, allowing unfettered cell division. Without telomerase, cells stop dividing or die within a limited number of generations. Unfortunately, the enzyme is also active in many cancer cells. Artandi and his collaborators found that blocking the inappropriate expression of the protein, called TCAB1, in human cancer cells keeps telomerase from reaching its DNA targets, called telomeres, and may limit the cell's life span.

"There are currently no effective telomerase inhibitors," said Artandi. "We've never really understood before how the enzyme gets to the telomeres; it's been a complete black box. Now we're starting to piece together how it happens, and that gives us more opportunities to interfere with its function."

Telomerase has been subject of intense research for years, but scientists have been stymied by the enzyme's large size and extreme rarity. Few cells in the adult body make the huge protein complex, and even they make only tiny amounts. As a result, only some members have been identified.

"It's been incredibly challenging to figure out all the protein components of telomerase," said Artandi, who refers to the unknown members of the complex as "dark matter." "We know how big the enzyme is, and it's clear that the known components don't add up to the total. Now we've identified one more member."

The researchers used a highly sensitive protein identification technique called mass spectrometry to ferret out TCAB1's presence in telomerase based on its ability to bind to another, known component of the enzyme. Early last year, Artandi's lab used the same technique to identify for the first time two other proteins — pontin and reptin — that are important for assembling the massive complex. This time around they identified TCAB1, a protein of previously unknown function.

Unlike pontin and reptin, TCAB1 is a true component of telomerase. But it's not required for the enzyme's activity. Rather, it recruits the telomerase complex to processing and holding areas in the nucleus of the cell called Cajal (pronounced "cuh-hall") bodies. Like a high-end garage, Cajal bodies apply the finishing touches to a variety of proteins that use small molecules of RNA to conduct their activities (telomerase, for example, uses an RNA molecule as a template for the DNA chain it tacks onto the ends of chromosomes). When appropriate, TCAB1 then chauffeurs the telomerase complex to the waiting end of a newly replicated chromosome.

"TCAB1 is absolutely necessary for the telomerase to make this jump from Cajal bodies to telomeres," said Artandi. "When we inhibited its activity in human cancer cells, the telomeres grew shorter," implying the cancer cells would die more quickly.

Prior to this study, TCAB1 had no known function. "Andy [Venteicher] found that TCAB1 binds not only telomerase, but also a specific class of small, non-coding RNA molecules that also end up in the Cajal bodies," said Artandi. He added that the protein may be a common biological shuttle responsible for delivering a variety of molecules to their destinations. He and his collaborators plan to continue their study of TCAB1 and also to identify other telomerase components.

"This is a story that's been unfolding over decades," said Artandi. "Telomerase is such a high-priority target for many diseases, but it's hard to attack when you know very little about it. But that's changing now."

The research was funded by the National Cancer Institute and the Leukemia and Lymphoma Society. Stanford graduate student Kelly McCann also participated in the research.

Monday, January 26, 2009

On A High-fat Diet, Protective Gene Variant Becomes Bad Actor

New evidence in mice bolsters the notion that a version of a gene earlier shown to protect lean people against weight gain and insulin resistance can have the opposite effect in those who eat a high-fat diet and are heavier, reveals a report in the January 7th issue of the journal Cell Metabolism, a Cell Press publication.

The findings suggest that the 12 percent of people who carry the so-called Ala12 version of the gene that serves as a master controller of fat differentiation will be more sensitive than most to the amount of fat in their diets. (That fat-moderating gene is called peroxisome proliferator-activated receptor gamma isoform 2, or Pparg2.)

The Ala12 gene variant in question is less active and less efficient in driving fat cells' formation than the more common Pro12 version, the researchers explained. As a result, individuals carrying Ala12 are generally less obese and more sensitive to insulin, but that can change if they shift to a less sensible, fat-laden meal plan.

Genetic testing for the variant might therefore be used as a diagnostic tool, said Johan Auwerx of Université Louis Pasteur in France and the Ecole Polytechnique Fédérale de Lausanne in Switzerland. "Through dietary counseling, carriers could be informed that they really need to watch out for high fat in their diets," he said.

The findings also raise a potential caution about the long-term effects of drugs called thiazolidinediones (TZDs) now in use for the treatment of diabetes, he added. Those drugs stimulate activity of the Pparg2 receptor. The findings suggest it may be better—at least in some settings—to have a less active receptor.

Auwerx's team first described the Ala12 version of Pparg2 about 10 years ago when they found in a Finnish and a Japanese American population living in Hawaii that the mutation lowered the risk of diabetes. Others tried to reproduce the findings in Americans to no avail. Indeed, the Americans in the followup study, who were generally heavier than the groups Auwerx had examined earlier, showed the exact opposite pattern.

That led to the idea that effects of the gene might somehow be sensitive to initial body weight, but an animal study was needed to sort out the underlying details.

The researchers now show that mice with two copies of the Ala12 variant, when fed a balanced diet of normal mouse chow, are leaner and have improved insulin sensitivity and better plasma lipid profiles than mice with two copies of Pro12. They also live longer.

When mice with the same genetic background were instead sustained on a diet high in fat, those benefits disappeared. In fact, those Ala12 animals grew somewhat more obese than mice with the more common Pro12 variant of the gene, though not significantly so.

The result shows an important interaction between the Pparg2 gene and the environment, they report. The underlying basis for the effect seems to depend on changes in the way the Pparg2 receptor interacts with its cofactors and in its sensitivity to a fat-produced hormone known as adiponectin, which influences blood sugar control and fatty acid breakdown.

" Collectively, our results establish the diet-dependent influence of Pparg2 Pro12Ala variant on metabolic control via modulated cofactor interaction and changes in gene expression patterns in mice," the researchers concluded. "These data hence consolidate Pparg2 as an important factor at the interface between genes and the environment and may provide avenues to better, possibly Pro12Ala genotype-dependent treatment strategies for insulin resistance in type 2 diabetes and the metabolic syndrome."

Monday, January 19, 2009

Stem Cell Troops Called To Repair The Body Using New Drug Combinations

Scientists have tricked bone marrow into releasing extra adult stem cells into the bloodstream, a technique that they hope could one day be used to repair heart damage or mend a broken bone, in a new study published today in the journal Cell Stem Cell. When a person has a disease or an injury, the bone marrow mobilises different types of stem cells to help repair and regenerate tissue. The new research, by researchers from Imperial College London, shows that it may be possible to boost the body's ability to repair itself and speed up repair, by using different new drug combinations to put the bone marrow into a state of 'red alert' and send specific kinds of stem cells into action.

In the new study, researchers tricked the bone marrow of healthy mice into releasing two types of adult stem cells – mesenchymal stem cells, which can turn into bone and cartilage and that can also suppress the immune system, and endothelial progenitor cells, which can make blood vessels and therefore have the potential to repair damage in the heart.

This study, funded by the British Heart Foundation and the Wellcome Trust, is the first to selectively mobilise mesenchymal stem cells and endothelial progenitor cells from the bone marrow. Previous studies have only been able to mobilise the haematopoietic type of stem cell, which creates new blood cells. This technique is already used in bone marrow transplants in order to boost the numbers of haematopoietic stem cells in a donor's bloodstream.

The researchers were able to choose which groups of stem cells the bone marrow released, by using two different therapies. Ultimately, the researchers hope that their new technique could be used to repair and regenerate tissue, for example when a person has heart disease or a sports injury, by mobilising the necessary stem cells.

The researchers also hope that they could tackle autoimmune diseases such as rheumatoid arthritis, where the body is attacked by its own immune system, by kicking the mesenchymal stem cells into action. These stem cells are able to suppress the immune system.

Dr Sara Rankin, the corresponding author of the study from the National Heart & Lung Institute at Imperial College London, said: "The body repairs itself all the time. We know that the skin heals over when we cut ourselves and, similarly, inside the body there are stem cells patrolling around and carrying out repair where it's needed. However, when the damage is severe, there are limits to what the body can do of its own accord.

"We hope that by releasing extra stem cells, as we were able to do in mice in our new study, we could potentially call up extra numbers of whichever stem cells the body needs, in order to boost its ability to mend itself and accelerate the repair process. Further down the line, our work could lead to new treatments to fight various diseases and injuries which work by mobilising a person's own stem cells from within," added Dr Rankin.

The scientists reached their conclusions after treating healthy mice with one of two different 'growth factors' – proteins that occur naturally in the bone marrow – called VEGF and G-CSF. Following this treatment, the mice were given a new drug called Mozobil.

The researchers found that the bone marrow released around 100 times as many endothelial and mesenchymal stem cells into the bloodstream when the mice were treated with VEGF and Mozobil, compared with mice that received no treatment. Treating the mice with G-CSF and Mozobil mobilised the haematopoietic stem cells – this treatment is already used in bone marrow transplantation.

The researchers now want to investigate whether releasing repair stem cells into the blood really does accelerate the rate and degree of tissue regeneration in mice that have had a heart attack. Depending on the outcome of this work, they hope to conduct clinical trials of the new drug combinations in humans within the next ten years.

The researchers are also keen to explore whether ageing or having a disease affects the bone marrow's ability to produce different kinds of adult stem cells. They want to investigate if the new technique might help to reinvigorate the body's repair mechanisms in older people, to help them fight disease and injury.

Saturday, January 17, 2009

How Did Life Begin? RNA That Replicates Itself Indefinitely Developed For First Time

One of the most enduring questions is how life could have begun on Earth. Molecules that can make copies of themselves are thought to be crucial to understanding this process as they provide the basis for heritability, a critical characteristic of living systems. New findings could inform biochemical questions about how life began.

Now, a pair of Scripps Research Institute scientists has taken a significant step toward answering that question. The scientists have synthesized for the first time RNA enzymes that can replicate themselves without the help of any proteins or other cellular components, and the process proceeds indefinitely.

The work was recently published in the journal Science.

In the modern world, DNA carries the genetic sequence for advanced organisms, while RNA is dependent on DNA for performing its roles such as building proteins. But one prominent theory about the origins of life, called the RNA World model, postulates that because RNA can function as both a gene and an enzyme, RNA might have come before DNA and protein and acted as the ancestral molecule of life. However, the process of copying a genetic molecule, which is considered a basic qualification for life, appears to be exceedingly complex, involving many proteins and other cellular components.

For years, researchers have wondered whether there might be some simpler way to copy RNA, brought about by the RNA itself. Some tentative steps along this road had previously been taken by the Joyce lab and others, but no one could demonstrate that RNA replication could be self-propagating, that is, result in new copies of RNA that also could copy themselves.

In Vitro Evolution

A few years after Tracey Lincoln arrived at Scripps Research from Jamaica to pursue her Ph.D., she began exploring the RNA-only replication concept along with her advisor, Professor Gerald Joyce, M.D., Ph.D., who is also Dean of the Faculty at Scripps Research. Their work began with a method of forced adaptation known as in vitro evolution. The goal was to take one of the RNA enzymes already developed in the lab that could perform the basic chemistry of replication, and improve it to the point that it could drive efficient, perpetual self-replication.

Lincoln synthesized in the laboratory a large population of variants of the RNA enzyme that would be challenged to do the job, and carried out a test-tube evolution procedure to obtain those variants that were most adept at joining together pieces of RNA.

Ultimately, this process enabled the team to isolate an evolved version of the original enzyme that is a very efficient replicator, something that many research groups, including Joyce's, had struggled for years to obtain. The improved enzyme fulfilled the primary goal of being able to undergo perpetual replication. "It kind of blew me away," says Lincoln.

Immortalizing Molecular Information

The replicating system actually involves two enzymes, each composed of two subunits and each functioning as a catalyst that assembles the other. The replication process is cyclic, in that the first enzyme binds the two subunits that comprise the second enzyme and joins them to make a new copy of the second enzyme; while the second enzyme similarly binds and joins the two subunits that comprise the first enzyme. In this way the two enzymes assemble each other — what is termed cross-replication. To make the process proceed indefinitely requires only a small starting amount of the two enzymes and a steady supply of the subunits.

"This is the only case outside biology where molecular information has been immortalized," says Joyce.

Not content to stop there, the researchers generated a variety of enzyme pairs with similar capabilities. They mixed 12 different cross-replicating pairs, together with all of their constituent subunits, and allowed them to compete in a molecular test of survival of the fittest. Most of the time the replicating enzymes would breed true, but on occasion an enzyme would make a mistake by binding one of the subunits from one of the other replicating enzymes. When such "mutations" occurred, the resulting recombinant enzymes also were capable of sustained replication, with the most fit replicators growing in number to dominate the mixture. "To me that's actually the biggest result," says Joyce.

The research shows that the system can sustain molecular information, a form of heritability, and give rise to variations of itself in a way akin to Darwinian evolution. So, says Lincoln, "What we have is non-living, but we've been able to show that it has some life-like properties, and that was extremely interesting."

Knocking on the Door of Life

The group is pursuing potential applications of their discovery in the field of molecular diagnostics, but that work is tied to a research paper currently in review, so the researchers can't yet discuss it.

But the main value of the work, according to Joyce, is at the basic research level. "What we've found could be relevant to how life begins, at that key moment when Darwinian evolution starts." He is quick to point out that, while the self-replicating RNA enzyme systems share certain characteristics of life, they are not themselves a form of life.

The historical origin of life can never be recreated precisely, so without a reliable time machine, one must instead address the related question of whether life could ever be created in a laboratory. This could, of course, shed light on what the beginning of life might have looked like, at least in outline. "We're not trying to play back the tape," says Lincoln of their work, "but it might tell us how you go about starting the process of understanding the emergence of life in the lab."

Joyce says that only when a system is developed in the lab that has the capability of evolving novel functions on its own can it be properly called life. "We're knocking on that door," he says, "But of course we haven't achieved that."

The subunits in the enzymes the team constructed each contain many nucleotides, so they are relatively complex and not something that would have been found floating in the primordial ooze. But, while the building blocks likely would have been simpler, the work does finally show that a simpler form of RNA-based life is at least possible, which should drive further research to explore the RNA World theory of life's origins.