Injection of human umbilical cord blood helps the aging brain

Injection of human umbilical cord blood helps the aging brain Monday, 10 March 2008 When human umbilical cord blood cells (UCBC) were injected into aged laboratory animals, researchers at the University of South Florida (USF) found improvements in the microenvironment of the hippocampus region of the animals’ brains and a subsequent rejuvenation of neural stem/progenitor cells. Published online at BMC Neuroscience, the research presented the possibility of a cell therapy aimed at rejuvenating the aged brain. “Brain cell neurogenesis decreases dramatically with increasing age, mostly because of a growing impoverishment in the brain’s microenvironment,” said co-author Alison Willing, PhD, of the USF Center of Excellence for Aging and Brain Repair. “The increase in neurogenesis we saw after injecting UCBCs seemed to be due to a decrease in inflammation.” According to lead author Carmelina Gemma, Ph.D., of the James A. Haley Veterans Administration Medical Center (VA) and USF, the decrease in neurogenesis that accompanies aging is a result of the decrease in proliferation of stem cells, not the loss of cells. “In the brain, there are two stem cell pools, one of which resides in the hippocampus,” explained graduate student and first author Adam Bachstetter. “As in other stem cell pools, the stem cells in the brain lose their capacity to generate new cells. A potent stressor of stem cell proliferation is inflammation.” Prior to this study, the research team led by Paula C. Bickford, Ph.D., of the VA and USF found that reducing neuroinflammation in aged rats by blocking the synthesis of the pro-inflammatory cytokine IL1B rescued some of the age-related decrease in neurogenesis and improved cognitive function. “We think that UCBCs may have a similar potential to reduce inflammation and to restore some of the lost capacity of stem/progenitor cells to proliferate and differentiate into neurons,” said Dr. Bickford. The study found that the number of proliferative cells increased within 24 hours following the UCBC injections into the aged laboratory rats and that the increased cell proliferation continued for at least 15 days following a single treatment. “We have shown that injections of UCBCs can reduce neuroinflammation,” concluded co-author Paul R. Sanberg, Ph.D. D.Sc. director of the Center of Excellence for Aging and Brain Repair. “Our results raise the possibility that a cell therapy could be an effective approach to improving the microenvironment of the aged brain and restoring some lost capacity.” ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Cardiovascular benefits of omega-3 fatty acids

Cardiovascular benefits of omega-3 fatty acids Monday, 10 March 2008 Thousands of research studies have documented how the oils known as omega-3 fatty acids can benefit the cardiovascular system, particularly among people diagnosed with coronary artery disease. The incredible volume of research on this topic creates difficulty for many physicians and patients to stay current with findings and recommendations related to these oils. In the March issue of Mayo Clinic Proceedings, contributors briefly summarize current scientific data on omega-3 fatty acids and cardiovascular health, focusing on who benefits most from their protective effects, recommended guidelines for administration and dosing, and possible adverse effects associated with their use. Two omega-3 fatty acids that have been associated with cardiovascular benefit, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are found in fish oils. The best source for DHA and EPA are fatty coldwater fish such as herring, mackerel, salmon and tuna. Fish oil supplements or algae supplements also can provide omega-3 fatty acids. Author James O’Keefe, M.D., a cardiologist from the Mid America Heart Institute in Kansas City, Mo., cites the results of several large trials that demonstrated the positive benefits associated with omega-3 fatty acids, either from oily fish or fish oil capsules. “The most compelling evidence for the cardiovascular benefit provided by omega-3 fatty acids comes from three large controlled trials of 32,000 participants randomized to receive omega-3 fatty acid supplements containing DHA and EPA or to act as controls,” explains Dr. O’Keefe. “These trials showed reductions in cardiovascular events of 19 percent to 45 percent. Overall, these findings suggest that intake of omega-3 fatty acids, whether from dietary sources or fish oil supplements, should be increased, especially in those with or at risk for coronary artery disease.” How much fish oil should people attempt to incorporate into their diets? According to Dr. O’Keefe, people with known coronary artery disease should consume about 1 gram per day, while people without disease should consume at least 500 milligrams (mg) per day. “Patients with high triglyceride levels can benefit from treatment with 3 to 4 grams daily of DHA and EPA,” says Dr. O’Keefe. “Research shows that this dosage lowers triglyceride levels by 20 to 50 percent.” About two meals of oily fish can provide 400 to 500 mg of DHA and EPA, so patients who need to consume higher levels of these fatty-acids may choose to use fish oil supplements to reach these targets. Dr. O’Keefe also notes that research supports the effectiveness of combining the consumption of fish oil with the use of cholesterol-lowering medications called statins. Combination therapy with omega-3 fatty acids and a statin is a safe and effective way to improve lipid levels and cardiovascular health beyond the benefits provided by statin therapy alone. Blood DHA and EPA levels could one day be used to identify patients with deficient levels and to individualize therapeutic recommendations. Dr. O’Keefe found little evidence of serious adverse effects associated with fish oil consumption. “In prospective placebo-controlled trials, no adverse effects were observed to occur at a frequency of more than 5 percent, and no difference in frequency was noted between the placebo and omega-3 fatty acid groups,” he says. The most commonly observed side effects include nausea, upset stomach and a “fishy burp.” Taking the supplement at bedtime or with meals, keeping fish oil capsules in the freezer or using enteric-coated supplements may help reduce burping and upset stomach symptoms. ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Genetic Research Unveils Common Origins for Distinct Clinical Diagnoses

Genetic Research Unveils Common Origins for Distinct Clinical Diagnoses Monday, 10 March 2008 Researchers at Johns Hopkins have discovered that two clinically different inherited syndromes are in fact variations of the same disorder. Reporting in the April issue of Nature Genetics, the team suggests that at least for this class of disorders, the total number and “strength” of genetic alterations an individual carries throughout the genome can generate a range of symptoms wide enough to appear like different conditions. “We’re finally beginning to blur the boundaries encompassing some of these diseases by showing that they share the same molecular underpinnings,” says Nicholas Katsanis, Ph.D., an associate professor of ophthalmology at the McKusick-Nathans Institute of Genetic Medicine at Hopkins. “This is important progress for several reasons. First, knowing what’s going on molecularly and being able to integrate rarer conditions under common mechanisms allows us to potentially help more people at once. Second, clinicians can finally begin to offer more accurate diagnoses based on what really matters: the state of affairs at the cellular/biochemical level. In time, this will empower genetic counselling and much improved patient management.” Katsanis’s team studies Bardet-Biedl syndrome (BBS), a rare so-called ciliopathy that is characterized by a combination of vision loss, obesity, diabetes, extra digits and mental defects and caused by faulty cilia, tiny hair-like projections found on almost every cell of the body. Recently they started looking at another disease, Meckel-Gruber syndrome (MKS), which also shows cilia dysfunction but is clinically distinct from BBS and generally associated with prenatal or newborn death. “While these two groups of patients exhibit such different clinical outcomes, the genes associated with both syndromes all seemed to be pointing at the same culprit: cilia,” says Katsanis. “So we wondered if BBS and MKS might actually represent different flavours of the same disease.” The researchers sequenced the MKS genes from 200 BBS patients and found six families that, in addition to carrying BBS genetic mutations, also carried mutations in MKS genes. To figure out what, if any, effect these MKS mutations have on BBS, the team used a system they previously developed in zebrafish. Knocking out BBS genes in zebrafish generates short fish with even shorter tails, among other malformations. Injecting normal BBS genes into these fish rescues them, resulting in normal looking fish. The researchers reasoned that if MKS and BBS are indeed the same condition, then fish with the MKS genes knocked out should mimic the BBS knockout fish. They did. The team then went on to test mutant versions of MKS genes in BBS fish and found that three genes originally attributed to MKS do indeed cause BBS or render the BBS defects more pronounced, increasing the number of BBS genes to 14 in total. “From a clinical perspective, these two syndromes look nothing alike, but molecularly, the genes involved clearly participate in the same fundamental processes,” says Katsanis. “This means that Meckel-Gruber and Bardet-Biedel actually represent a continuum of one disease. This never would have been discovered in the clinic-only molecular analysis can reveal these things.” But what does this mean for clinicians and the diagnosis and treatment of these syndromes? Katsanis hopes that the growing body of molecular data will help move medicine away from symptom-defined syndromes, which can leave clinicians struggling with ambiguous diagnoses, to approaching disorders from a molecular standpoint. “We now have the possibility of merging several rare disorders,” he says. “And their gross sum now turns out to be fairly common; hopefully this will now put them on the radar for drug development and other therapies.” Authors on the paper are Carmen Leitch, Norann Zaghloul, Erica Davis and Katsanis, all of Hopkins; Corrine Stoetzel and Helene Dollfus of Université Louis Pasteur, Strasbourg, France; Anna Diaz-Font, Suzanne Rix and Philip Beales of University College London, UK; Majid Al-Fadhel and Wafaa Eyaid of King Fahad Hospital, Riyadh, Saudi Arabia; Richard Alan Lewis of Baylor College of Medicine, Houston, Texas.; Eyal Banin of Hadassah-Hebrew University Hospital, Jerusalem, Israel; and Jose Badano, previously of Hopkins and now at the Institut Pasteur de Montevideo, Uruguay. ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Drosophila Drug Screen for Fragile X Syndrome

Promising compounds and potential drug targets found Monday, 10 March 2008 Scientists using a new drug screening method in Drosophila (fruit flies), have identified several drugs and small molecules that reverse the features of fragile X syndrome – a frequent form of mental retardation and one of the leading known causes of autism. The discovery sets the stage for developing new treatments for fragile X syndrome. The results of the research by lead scientist Stephen Warren, PhD, chair of the Department of Human Genetics at Emory University School of Medicine, are published online in the journal Nature Chemical Biology. Dr. Warren led an international group of scientists that discovered the FMR1 gene responsible for fragile X syndrome in 1991. Fragile X syndrome is caused by the functional loss of the fragile X mental retardation protein (FMRP). Currently there is no effective drug therapy for fragile X syndrome, and previously no assays had been developed to screen drug candidates for the disorder. During the past 17 years, intense efforts from many laboratories have uncovered the fundamental basis for fragile X syndrome. Scientists believe FMRP affects learning and memory through regulation of protein synthesis at synapses in the brain. One leading view, proposed by Dr. Warren and colleagues, suggests that over stimulation of neurons by the neurotransmitter glutamate is partly responsible for the brain dysfunction resulting from the loss of FMRP. In their current experiment, Emory scientists used a Drosophila model lacking the FMR1 gene. These fruit flies have abnormalities in brain architecture and behaviour that parallel abnormalities in the human form of fragile X syndrome. When FMR1-deficient fly embryos were fed food containing increased levels of glutamate, they died during development, which is consistent with the theory that the loss of FMR1 results in excess glutamate signalling. The scientists placed the FMR1-deficient fly embryos in thousands of tiny wells containing food with glutamate. In addition, each well contained one compound from a library of 2,000 drugs and small molecules. The scientists’ uncovered nine molecules that reversed the lethal effects of glutamate, using this screening method. The three top identified compounds were known activators of GABA, a neural pathway already known to inhibit the effects of glutamate. In the study, GABA reversed all the features of fragile X syndrome in the fruit flies, including deficits in the brain's primary learning centre and behavioural deficits. The screening also identified other neural pathways that may have a parallel role in fragile X syndrome and could be targets for drug therapy. "Our discovery of glutamate toxicity in the Drosophila model of fragile X syndrome allowed us to develop this new screen for potential drug targets," notes Dr. Warren. "We believe this is the first chemical genetic screen for fragile X syndrome, and it highlights the general potential of Drosophila screens for drug development. Most importantly, it identifies several small molecules that significantly reverse multiple abnormal characteristics of FMR1 deficiency. It also reveals additional pathways and relevant drug targets. These findings open the door to development of effective new therapies for fragile X syndrome." First author of the article was Shuang Chang, postdoctoral student in Emory's Department of Human Genetics. Other authors included Steven M. Bray and Peng Jin from Emory, Zigang Li from the University of Chicago and Daniela C. Zarnescu from the University of Arizona. The research was supported by the National Institutes of Health, the Fragile X Research Foundation, and the Colonial Oaks Foundation. Dr. Warren is chair of the scientific advisory board for Seaside Therapeutics, which is developing drugs for fragile X syndrome. ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Toxins In Cigarette Smoke Prevent Stem Cells From Becoming Cartilage

Toxins In Cigarette Smoke Prevent Stem Cells From Becoming Cartilage Monday, 03 March 2008 A toxic pollutant spread by oil spills, forest fires and car exhaust is also present in cigarette smoke, and may represent a second way in which smoking delays bone healing, according to research presented today at the annual meeting of the Orthopaedic Research Society in San Francisco. In 2005, researchers from the University of Rochester Medical Center identified one ingredient in smoke, nicotine, that delays bone growth by influencing gene expression in the two-step bone healing process: stem cells become cartilage; cartilage matures into bone. In the current study, some of the same researchers found that a second smoke ingredient, the polyaromatic hydrocarbon benzo(a)pyrene (BaP), also slows bone healing, but in a different way. Smoking has been shown to delay skeletal healing by as much as 60 percent following fractures. Slower healing means a greater chance of re-injury and can lead to chronic pain and disability. The obvious solution is for smokers to quit when they get hurt, but studies show that just 15 percent can. “Our results provide the first evidence that BaP prevents stem cells from becoming cartilage cells as part of healing,” said Regis J. O'Keefe, M.D., Ph.D., chair of the Department of Orthopaedics and Rehabilitation at the Medical Center and a study investigator. “These findings extend our understanding of the impact of cigarette smoke on a process that is critical to fracture repair. Perhaps down the road we will be able to speed bone healing among smokers in more than one way.” Study Details Gene expression is the process by which instructions encoded in genes are followed for the building of proteins, the workhorses that make up the body’s organs and carry its signals. In the current study, polymerase chain reaction (PCR), a technique that measures gene expression levels, revealed the genetic changes caused by exposure to BaP in mouse stem cells. Among the many factors that influence gene expression are transcription factors, proteins designed to direct genes to create more or less of a protein. One such factor is Sex Determining Region Y-box 9 (SOX-9), required for the transition of stem cells into cartilage cells. The PCR results show that BaP in cigarette spoke interferes with SOX-9 expression in mesenchymal stem cells, blocking their conversion into cartilage cells. When this group of stem cells is free to differentiate, the newly formed cartilage cells immediately begin manufacturing collagen 2, the tough, fibrous protein framework for cartilage. Along with interfering with SOX-9, BaP was also found to reduce levels of type II collagen gene expression. Past studies had shown that stem cells involved in cartilage formation contain proteins known to react with BaP called aryl hydrocarbon receptors. The current results suggest that BaP binding with these receptors may suppress SOX-9 activity, reducing the number of stem cells that turn into cartilage cells and the amount of collage produced. No one knows what such receptors are doing in these cells in the first place, but one theory has it that they signal cellular machinery to metabolize toxins. The study compared the effect of BaP versus that of cigarette smoke extract, a substance representing all the ingredients in cigarette smoke. The hope was to confirm BaP as the specific cause of the observed effect on SOX-9. Results indeed suggest BaP alone may responsible for this specific mechanism of healing delay, since its effect was equal to the extract. In addition measuring gene expression levels, researchers also conducted tests to show the effect of BaP visually. When newly differentiated cartilage cells begin to produce collagen in a culture dish, little mounds or nodules of collagen can be visualized using a stain. Staining experiments captured images showing BaP to “completely inhibit” collagen nodule deposition. Along with O’Keefe, the Medical Center effort was led by Ming Kung, Donna Hoak, HsinChiu Ho, Edward Puzas and Michael Zuscik, all within the Department of Orthopaedics at the Medical Center. "Smoking reduces the rate at which the two sides of a fracture come together," said Michael Zuscik, Ph.D., associate professor in the Department of Orthopaedics and Rehabilitation at the Medical Center. "We believe this new research will establish for the first time the mechanisms by which polyaromatic hydrocarbons interfere with the healing process.” ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Giant Panda Genome to Be Sequenced

Giant Panda Genome to Be Sequenced Thursday, 06 March 2008 BGI-Shenzhen is pleased to announce the launch of the International Giant Panda Genome Project. This announcement follows on the heels of the Panda Genome workshop held on January 21–22, 2008, in Shenzhen, China. Dr. Hongmei Zhu, a scientist from BGI-Shenzhen, stated that, "The goal of this project is to finish the sequencing and assembling of the draft sequence within six months." The giant panda is a much loved animal all over the world and is considered a symbol of China, as illustrated by its being one of the mascots for the upcoming Olympics in Beijing. The excitement surrounding the launch of this ambitious project, however, has been built around how this new genomic information will have extensive impact in numerous scientific areas — from ecology to evolution to sequencing technology. Such data will aid in understanding the genetic and biological underpinnings of this unique species, especially with regard to its very specific niche in the environment and the molecular mechanisms of its evolution. Of special interest is that these data will be extremely useful for protecting and monitoring this endangered species and will provide information on the impact of captive breeding. In addition, it will have considerable use in controlling diseases that could devastate these fragile populations. Because scientists will be utilizing the latest Now-Gen sequencing technology to carry out this research, this project will also have far-reaching implications for promoting advances in sequencing tools and techniques. “The most noteworthy aspect of the project,” said Oliver Ryder of the San Diego Zoo’s Center for Conservation and Research for Endangered Species (CRES) and a participant at the January workshop, “is that it is the first genome project to be undertaken specifically to gather information that will contribute to conservation efforts for an endangered species. The giant panda is a global conservation symbol and deserving of such an effort.” Ya-Ping Zhang, a member of the Chinese Academy of Sciences and Director of the Kunming Institute of Zoology at the Chinese Academy of Sciences, put equal emphasis on the evolutionary impact of these studies, saying, “the genome project will help scientists to understand the genetic basis for giant panda adaptation to its special diet and behavioral style, and to reveal the history of population isolation and migration.” Often referred to as a living fossil, given evidence that its ancestors existed in China over 8 million years ago, the giant panda has been the focal point of many research projects. So far, however, little research has been done on a genomic scale. The giant panda has a genome size of about 3 Gb, which is approximately the same size as the human genome, and is thought to have 20,000–30,000 genes. Taxonomy and genetic studies indicate that the giant panda is most closely related to bears, not to raccoons as was once considered, given their unique physical characteristics. The Giant Panda is the logo and flagship species for the World Wide Fund for Nature (WWF), China. Zhiyong Fan, Species Program Director of the WWF-China, made comments based on the importance of protecting the panda in the wild: “The project is a really ambitious. Its contribution to wild panda conservation has been discussed in the workshop. We are looking forward to its effort”. Dr. Lin He, a member of the Chinese Academy of Sciences who works at both Shanghai Jiao Tong University and Fudan University, noted that the panda sequence obtained from this project will greatly benefit our understanding of the reduced fecundity in pandas when living under certain environmental conditions. This is a major issue for breeding programs that are carried out to strengthen the panda species as a whole. Dr. Lin He also raised an important point about how this sequence will further aid in learning about the interaction between genetics and the environment, and their impact on the physiology and pathology of the panda. The panda to be sequenced for the Giant Panda Genome Project will be chosen from the Chengdu and Wolong breeding centers. In addition to producing a high quality genome sequence, the researchers will do a survey of the genetic variations in the panda population. The fine map of the panda’s genome and the transcriptome studies will provide an unparalleled amount of information to aid in understanding both current and past status of the species, including historical population size, current levels of inbreeding, precise estimates of gene-flow, and past connectedness between the two different mountain-top giant panda populations. In addition to researchers at BGI-Shenzhen, the current participants in this project consist of scientists from all around the globe: including researchers from the Kunming Institute of Zoology at the Chinese Academy of Sciences; the Institute of Zoology at the Chinese Academy of Sciences (Beijing); Chengdu Research Base of Giant Panda Breeding; the China Research and Conservation Center for the Giant Panda (Wolong); the Beijing Institute of Genomics, the Chinese Academy of Sciences; Beijing Genomics Institute (BGI); BGI-Hangzhou; the University of Alberta (Canada); Cardiff University (UK); Fudan University (Shanghai); Sichuan University; Southeast University (Nanjing); Sun Yat-Sen University (Guangzhou); the University of California at Berkeley; the University of Copenhagen; the University of Hong Kong; the University of Washington (Seattle); the World Wide Fund for Nature, China; and the Zoological Society of San Diego. BGI-Shenzhen also announced the First Asian Genome project last October and participated in the 1000 genomes project this January. ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

New Stem Cell Technique Improves Genetic Alteration

Efficiency of method could lead to better disease study and future stem cell cures Friday, 07 March 2008 UC Irvine researchers have discovered a dramatically improved method for genetically manipulating human embryonic stem cells, making it easier for scientists to study and potentially treat thousands of disorders ranging from Huntington’s disease to muscular dystrophy and diabetes. The technique for the first time blends two existing cell-handling methods to improve cell survival rates and increase the efficiency of inserting DNA into cells. The new approach is up to 100 times more efficient than current methods at producing human embryonic stem cells with desired genetic alterations. “The ability to generate large quantities of cells with altered genes opens the door to new research into many devastating disorders,” said Peter Donovan, professor of biological chemistry and developmental and cell biology at UCI, and co-director of the UCI Sue and Bill Gross Stem Cell Research Center. “Not only will it allow us to study diseases more in-depth, it also could be a key step in the successful development of future stem cell therapies.” This study appears online this week in the journal Stem Cells. Donovan and Leslie Lock, assistant adjunct professor of biological chemistry and developmental and cell biology at UCI, previously identified proteins called growth factors that help keep cells alive. Growth factors are like switches that tell cells how to behave, for example to stay alive, divide or remain a stem cell. Without a signal to stay alive, the cells die. The UCI scientists – Donovan, Lock and Kristi Hohenstein, a stem cell scientist in Donovan’s lab – used those growth factors in the current study to keep cells alive, then they used a technique called nucleofection to insert DNA into the cells. Nucleofection uses electrical pulses to punch tiny holes in the outer layer of a cell through which DNA can enter the cell. With this technique, scientists can introduce into cells DNA that makes proteins that glow green under a special light. The green colour allows them to track cell movement once the cells are transplanted into an animal model, making it easier for researchers to identify the cells during safety studies of potential stem cell therapies. Scientists today primarily use chemicals to get DNA into cells, but that method inadvertently can kill the cells and is inefficient at transferring genetic information. For every one genetically altered cell generated using the chemical method, the new growth factor/nucleofection method produces between 10 and 100 successfully modified cells, UCI scientists estimate. With the publication of this study, the new method now may be used by stem cell scientists worldwide to improve the efficiency of genetically modifying human embryonic stem cells. “Before our technique, genetic modification of human embryonic stem cells largely was inefficient,” Hohenstein said. “This is a stepping stone for bigger things to come.” Scientists can use the technique to develop populations of cells with abnormalities that lead to disease. They can then study those cells to learn more about the disorder and how it is caused. Scientists also possibly could use the technique to correct the disorder in stem cells, then use the healthy cells in a treatment. The method potentially could help treat monogenic diseases, which result from modifications in a single gene occurring in all cells of the body. Though relatively rare, these diseases affect millions of people worldwide. Scientists currently estimate that more 10,000 human diseases are monogenic, according to the World Health Organization. Examples include Huntington’s disease, sickle cell anaemia, cystic fibrosis and haemophilia. UCI is at the forefront of stem cell research. The Sue and Bill Gross Stem Cell Research Center promotes basic and clinical research training in the field of stem cell biology. More than 60 UCI scientists use stem cells in their studies. These scientists study spinal cord injuries, brain injuries and central nervous system diseases such as multiple sclerosis, Alzheimer’s and Huntington’s. They also study muscular dystrophy, diabetes, cancer and other disorders. April Pyle of UCLA and Jing Yi Chern of Johns Hopkins University also worked on the genetic modification study, which was funded by the National Institutes of Health. ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Molecular Alliance That Sustains Embryonic Stem Cell State

Allied proteins known as transcription factors Tuesday, 04 March 2008 One of the four ingredients in the genetic recipe that scientists in Japan and the US followed last year to persuade human skin cells to revert to an embryonic stem cell state, is dispensable in ES cells, thanks to the presence of a molecular alliance between a specific group of key proteins known as transcription factors, a research team led by the Genome Institute of Singapore (GIS) under the Agency for Science, Technology and Research (A*STAR) reports in the current issue of Nature Cell Biology. The reprogramming factor - Klf4, one of the transcription factors that determine whether a cell's genes are active or silent - has at least two other sibling molecules that will substitute Klf4 to maintain a pluripotent embryonic stem (ES) cell state, the GIS-led team said. Klf4 (also known as gut-enriched Krüppel-like factor or Gklf) belongs to the Krüppel-like factor (Klf) family of transcription factors that regulate numerous biological processes including proliferation, differentiation, development and apoptosis, or programmed cell death. Since reprogramming mature cells to the ES state may provide a ready source of tissue for biomedical research and clinical treatment of diseases such as Parkinson's and diabetes, several laboratories, including GIS, are trying to better understand and finely tune the reprogramming process. The team looks for clues for what these reprogramming ingredients are doing in ES cells. "Klf4 has been a mysterious player among the four reprogramming factors. As taking out Klf4 in ES cells did not have any apparent effects, it is difficult to reconcile why such a potent reprogramming factor has no role in ES cell biology," said GIS scientist Ng Huck Hui, Ph.D., who headed the research team. Other members of the team include researchers from the National University of Singapore and University of Illinois at Urbana-Champaign. The GIS research team found that when Klf4 was depleted, Klf2 and Klf5 took over Klf4's role. To understand the molecular basis of the Klf4 redundancy, the scientists studied the DNA binding and transcription activation properties of the three Klfs and found that the profiles of the three Klfs were strikingly similar. "Most important, the data showed that the other Klfs were bound to the target sites when one of them was depleted." said Dr. Ng. "These Krüppel-like factors form a very powerful alliance that work together on regulating common targets. The impact of losing one of them is masked by the other two sibling molecules." For example, Klfs were found to regulate the Nanog gene and other key genes that must be active for ES cells to be pluripotent, or capable of differentiating into virtually any type of cells. Nanog gene is one of the key pluripotency genes in ES cells. "We suggest that Nanog and other genes are key effectors for the biological functions of the Klfs in ES cells," Dr. Ng said. "Together, our study provides new insight into how the core Klf circuitry integrates into the Nanog transcriptional network to specify gene expression unique to ES cells. The way these factors network with key genes in ES cells suggest a way of how Klf4 (along with the other three reprogramming factors) can jump-start the ES cell gene expression engine in adult cells," he noted. Although these three Klfs are involved in diverse biological roles, their redundant roles have not been previously appreciated. "Dr. Ng and his colleagues at the Genome Institute of Singapore again have unravelled another intricacy of what makes a stem cell," said Edison Liu, M.D., Executive Director of GIS. "This work brings us closer to a detailed understanding of the genetic components of stemness." Alan Colman, Ph.D., internationally recognized leader in stem cell research, said, "Klf4 is a transcription factor that came to prominence recently because it was one of four factors used to reprogram somatic cells back to the pluripotent state seen in embryonic stem cells.” "The mystery of the role of Klf4 has been revealed in studies by Huck Hui and colleagues," added Colman, Executive Director of the Singapore Stem Cell Consortium, which like GIS, is part of Singapore's A*STAR. "They show for the first time that Klf4 itself is not needed for the maintenance of the pluripotent state in ES cells; however, this is because the cells have a number of other Klf-like transcription factors that can substitute for Klf4." ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---

Role of Tiny RNAs In Controlling Stem Cell Fate

Understanding these key regulatory factors is critical for potential therapeutic use of stem cells Thursday, 06 March 2008 Researchers at the Gladstone Institute of Cardiovascular Disease (GICD) and the University of California, San Francisco have identified for the first time how tiny genetic factors called microRNAs may influence the differentiation of pluripotent embryonic stem (ES) cells into cardiac muscle. As reported in the journal Cell Stem Cell, scientists in the lab of GICD Director, Deepak Srivastava, MD, demonstrated that two microRNAs, miR-1 and miR-133, which have been associated with muscle development, not only encourage heart muscle formation, but also actively suppress genes that could turn the ES cells into undesired cells like neurons or bone. “Understanding how pluripotent stem cells can be used in therapy requires that we understand the myriad processes and factors that influence cell fate,” said Dr. Srivastava. “This work shows that microRNAs can function both in directing how ES cells change into specific cells — as well as preventing these cells from developing into unwanted cell types. ” The differentiation of ES cells into heart cells or any other type of adult cell is a very complicated process involving many factors. MicroRNAs, or miRNAs, seem to act as rheostats or “dimmer switches” to fine-tune levels of important proteins in cells. More than 450 human miRNAs have been described and each is predicted to regulate tens if not hundreds of proteins that may determine cellular differentiation. While many ES cell-specific miRNAs have been identified, the role of individual miRNAs in ES cell differentiation had not previously been determined. The Gladstone team showed that miRNAs can control how pluripotent stem cells determine their fate, or “cell lineage” – in this case as cardiac muscle cells. Specifically, they found that miR-1 and miR-133 are active at the early stages of heart cell formation, when an ES cell is first “deciding” to become mesoderm, one of the three basic tissue layers in mammals and other organisms. Activity of either miR-1 or miR-133 in ES cells caused genes that encourage mesoderm formation to be turned on. Equally important, they caused other genes that would have told the cell to become ectoderm or endoderm to turn off. For example, expression of a specific factor called Delta-like 1 was repressed by miR-1. Removal of this factor from cells by other methods also caused the cells to begin transforming into heart cells. “Our findings provide insight into the fine regulation of cells and genes that is needed for a heart to form,” said Kathy Ivey, PhD, a California Institute of Regenerative Medicine (CIRM) postdoctoral fellow and lead author on the study. “By better understanding this complicated system, in the future, we may be able to identify ways to treat or prevent childhood and adult diseases that affect the heart.” The Gladstone team included Alecia Muth, Joshua Arnold, Jason Fish, Edward Hsaio and Bruce Conklin. They were joined by USCF’s Frank King, Ru-Fang Yeh and Harold S. Bernstein. The research was supported by the National Institutes of Health, the California Institute of Regenerative Medicine and the Lynda and Stewart Resnick Foundation. Reference: MicroRNA Regulation of Cell Lineages in Mouse and Human Embryonic Stem Cells Cell Stem Cell, Vol 2, 219-229, 06 March 2008 ......... ZenMaster

---

For more on stem cells and cloning, go to CellNEWS at http://www.geocities.com/giantfideli/index.html

---