Reported in the Oct. 3, 2008 issue of Cell, the findings–from a study in mice–point to a completely new approach to treating and preventing obesity in humans.  The discovery also offers hope for new ways to treat related disorders, such as type 2 diabetes and cardiovascular diseases–the most prevalent health problems in the United States and the rest of the developed world.

Led by Dongsheng Cai, an assistant professor of physiology at the UW School of Medicine and Public Health, the researchers looked specifically at the hypothalamus–the brain structure responsible for maintaining a steady state in the body–and for the first time found that a cell-signaling pathway primarily associated with inflammation also influences the regulation of food intake.  Stimulating the pathway led the animals to increase their energy consumption, while suppressing it helped them maintain normal food intake and body weight.

The research stems from recent explorations into the problem called metabolic inflammation, a by-product of too much food or energy consumption.  Unlike the classical inflammation typically observed in infections, injuries and diseases such as cancer, the metabolic inflammation seen in obesity-related diseases is much milder, doesn’t lead to overt symptoms or cause tissues damage.

“Metabolic inflammation is a chronic, low-grade condition consisting of inflammatory-like responses at the molecular level.  It has many downstream consequences,” says Cai.  “It causes cellular dysfunction, which can decrease the regulation of several physiological processes, including metabolism.”

Scientists believe that metabolic inflammation may be at the core of many chronic, obesity-related metabolic disorders that are so common today, he adds.

Cai and his team zeroed in on NF-kappaB, a protein complex that can be activated specifically by IKKbeta to induce inflammatory reactions in many cell systems.

In earlier studies at Harvard, Cai and colleagues found that the pathway interrupted sugar, fat or protein metabolism in tissues where metabolism typically takes place–liver, fat and skeletal muscle.  Feeding mice high-sugar and high-fat diets activated the pathway in these tissues.

Once he arrived at the SMPH three years ago, Cai began to consider whether metabolic inflammation might affect “higher-up” players in the central nervous system, particularly the hypothalamus.  This brain structure is a critical master regulator of appetite and energy balance, and also controls metabolism in the peripheral tissues he had studied before.  But nobody knew how the hypothalamus might contribute to the development of metabolic diseases such as obesity and diabetes.

“We wanted to learn whether the pathway or pathways underlying metabolic inflamm ation could affect metabolism regulators in the central nervous system,” he says.

In the current study, Cai and his team found first that IKKbeta/NF-kappaB does indeed exist in specific neurons in the hypothalamus.  The pathway is much more abundant in the hypothalamus than in peripheral tissue, and it normally remains inactive in the brain.

The researchers next showed that over-nutrition through high-fat diet feeding activates IKKbeta/NF-kappaB, specifically in neurons in the hypothalamus.

“When we knocked out the IKKbeta gene to suppress NF-kappaB activity in these neurons, the animals were significantly protected from energy over-consumption and obesity development,” Cai says.

The researchers also examined a cell component called the endoplasmic reticulum (ER), shown recently to be involved in metabolic diseases involving over-nutrition, to see if it might play a role in linking over-nutrition to activate IKKbeta/NF-kappaB in the hypothalamus.

“At the intracellular level, when the ER is challenged with over-nutrition, this leads to ER stress, which can push the IKKbeta/NF-kappaB pathway to an active state, although the involved reactions could be quite complicated,” Cai says.

In several experiments, the researchers found that ER stress caused by over-nutrition activated IKKbeta/NF-kappaB in the hypothalamus.  Suppressing ER stress in the central nervous system significantly preserved normal regulation of food intake and prevented obesity.

Cai says there’s still a lot of work to be done.  His group has begun studying IKKbeta/NF-kappaB’s connections to other pathways and regulations in the hypothalamus.

“The ultimate goal will certainly be to identify a selective and effective suppressor of the pathway to target related neurons,” he says.

But Cai continues to look at the big picture, seeking answers to questions such as: “How does the environment connect to the genetics that seem to underlie the obesity epidemic?  What are the key steps that have led to the dramatic rise of diabetes in the past three decades?  And Why can’t the body adjust to changes that have occurred in the way people eat and what they eat?”

Researchers may have found the key to engineering plants capable of thriving in environments laden with toxic aluminum, according to a report published online on October 2nd in Current Biology, a Cell Press publication.  Aluminum (Al)—a metal that is generally plentiful in the earth’s crust—causes particular problems for farmers in South America, Africa, and Indonesia, where acidic environments turn the metal into a form that stunts the growth of plants and especially plant roots.

” We found that a single change in one plant factor required for monitoring of and response to DNA damage results in a profound increase in Al tolerance,” said Paul Larsen of the University of California-Riverside.

That discovery was unexpected, he said, because scientists had believed Al could have a wide range of detrimental effects, binding to virtually any negatively charged molecule within cells.  If that were true, getting around Al toxicity would be no easy task since any single change in plants would result in only incremental increases in Al tolerance.

” Surprisingly, we found that elimination of just one factor results in a mutant root that can now thrive in an Al toxic environment,” Larsen said.  The critical factor, known as AtATR, serves as a “checkpoint” for cell division, he explained.  Its job is to assess whether a cell should divide or not, on the basis of the integrity of the cell’s DNA.  “Mutations that disrupt the function of AtATR effectively destroy this self-assessment activity and allow cells that otherwise would be forced to differentiate [into mature plant tissue] to continue dividing.”

The results present a new view of the causes of Al toxicity.  Rather than suffering from the metal’s cumulative toxic effects as had been believed, it appears Al itself triggers the AtATR-controlled self-assessment pathway to shut down growth.

The findings made in the model plant Arabidopsis offer “readymade” tools for genetically engineering crop plants incapable of restricting root growth in response to Al toxicity, Larsen said.  He anticipates that introduction of the mutant versions of AtATR into crop plants would override the existing assessment mechanisms and allow for continued cell division in soils that would normally inhibit root growth.

The new results may offer insight into Al toxicity not only in economically important agricultural crops, but also in animals, given that ATR genes are universally found in plants and animals, where they serve in various capacities related to DNA-damage assessment.

” To date, no one has been able to discern which targets of Al are critical to the manifestation of Al toxicity in either plant or animals, partly due to the predicted complexity of Al toxicity,” he said.  “This work clearly argues that DNA damage and response to this damage is paramount.”

Breakthroughs in cytogenetic technologies, which focus on subtle alterations in genes and chromosomes, are enabling a new level of detail and accuracy in the diagnosis of complex and unexplained developmental problems in children.

The availability of this new information can help clinicians shift to a “genotype first” model of diagnosis, according to David H. Ledbetter, PhD, Woodruff professor of human genetics at Emory University and director of the Division of Medical Genetics.

Ledbetter’s editorial on “Cytogenetic Technology–Genotype and Phenotype,” is published online this week by the New England Journal of Medicine.  It accompanies an article by Heather Mefford and colleagues about using new cytogenetic technologies to identify microdeletions and microduplications in a specific region of chomosome 1q21.1 in patients with unexplained mental retardation, autism or congenital anomalies

Cytogenetic arrays that reveal DNA microdeletions and additions, including single-copy changes of a few hundred base pairs, beadchips that detect single-nucleotide polymorphisms (SNPs) and tests called comparative genomic hybridization have led to an exciting renaissance of genetics-based syndrome delineation, says Ledbetter in his editorial.

“In the early 1960s we began discovering the relationship between chromosome imbalance and diseases and syndromes, such as Down syndrome,” says Ledbetter.  “This was based on identifying multiple patients with the same cytogenetic abnormality and similar clinical symptoms.  Ever since then, technology breakthroughs have allowed us to identify new syndromes and ever more subtle genetic differences.”

The current proliferation of new genetic information has led researchers to discover that many small genetic variations are common and mostly benign in the human population.  This means the relationship between DNA variations and disease must be analyzed even more carefully in order to find accurate connections.  In order to prove that a genetic difference is directly related to a particular syndrome, notes Ledbetter, researchers must show that the difference is never found in normal control individuals or at least is found with significantly less frequency.

Also, researchers have found that a particular genetic variation may have only a mild effect in a parent but a much more severe effect in a child who inherits the same variant.  And a group of children may have a variety of different problems resulting from the same gene variation.  Whole-genome cytogenetic arrays are becoming much more common, however, which is bringing genetic testing to the level of everyday medicine.

“So many variations of developmental disorders and syndromes have been discovered that genetic testing has become essential for making a specific clinical diagnosis,” says Ledbetter.  “Although more information has made the job of a diagnostician even more challenging, it also is leading to more accurate diagnoses and should lead to much more effective treatments.”

Some of the most challenging obstacles limiting the reprogramming of mature human cells into stem cells may not seem quite as daunting in the near future.  Two independent research papers, published by Cell Press in the September 11th issue of the journal Cell Stem Cell, describe new tools that provide invaluable platforms for elucidating the molecular, genetic, and biochemical mechanisms associated with reprogramming.  The new findings also offer considerable hope toward making the reprogramming process more therapeutically relevant.

Although scientists have successfully reprogrammed mature human skin cells into induced pluripotent stem (iPS) cells by expressing a few key transcription factors, the conversion has been extremely inefficient.  “Little is known about the mechanisms by which reprogramming occurs, in part because of the low efficiency,” says senior study author Dr. Konrad Hochedlinger from the Harvard Stem Cell Institute.  In addition, the iPS cells created thus far have been generated with retroviruses and noninducible lentiviruses, both of which have major limitations that are not compatible with clinical applications.

The Hochedlinger group created a drug-inducible viral system to generate human iPS cells that were molecularly and functionally similar to human embryonic stem cells.  This method was unique in that it allowed the researchers to create iPS cells by using the drug doxycycline to control expression of the necessary factors that had been delivered to the cells with viruses.

The researchers then found that when doxycycline was removed and these “primary” iPS cells differentiated to mature cells, another exposure to the drug reactivated the genes required for reprogramming and induced generation of “secondary” iPS cells at a frequency that was far greater that the initial “primary” conversion.  The idea of generating these secondary cells was conceived in previous experiments with mice performed in the lab of Dr. Rudolf Jaenisch from the Massachusetts Institute of Technology.

“The secondary system will enable chemical and genetic screening efforts to identify key molecular constituents of reprogramming, as well as important obstacles in this process, and will ultimately lend itself as a powerful tool in the development and optimization methods to produce human iPS cells,” explains Dr. Hochedlinger.

In a separate paper, Dr. Jaenisch’s group reports on their success in deriving human secondary iPS cells using doxycycline-inducible transgenes.  “The drug-inducible system we describe represents a novel, predictable, and highly reproducible platform to study the kinetics of iPS cell generation,” says Dr. Jaenisch.  “Further, the genetic homogeneity of secondary cells makes chemical and genetic screening approaches to enhance reprogramming efficiency or to replace any of the original reprogramming factors feasible.”

Both research teams found that generation of secondary human iPS cells required less time than the initial reprogramming.  Interestingly, the time required to generate iPS cells varied among the types of skin cells that were used.  For instance, human fibroblasts required several weeks, while keratinocytes required only about 10 days.  “The fast kinetics of reprogramming observed for keratinocytes suggests that these cells would be useful for development and optimization of methods to reprogram cells by transient delivery of factors,” suggests Dr. Hochedlinger.

The combined results from both research groups represent a major advance toward more efficient strategies for reprogramming differentiated human cells into iPS cells.  The methods described here will not only provide critical insight into the reprogramming process, but also, because of the abbreviated time frame, may lead to the generation of cells that will be amenable for therapies, as reprogramming might be achievable without the prohibitive viruses or genetic modifications.

Scientists investigating the mechanisms of Down Syndrome (DS) have revealed the earliest developmental changes in embryonic stem cells caused by an extra copy of human chromosome 21 – the aberrant inheritance of which results in the condition. Their study is published online today (Thursday 4 September) in the American Journal of Human Genetics.

Lead by Dean Nizetic, Professor of Cellular and Molecular Biology at Barts and The London School of Medicine and Dentistry, the team utilised embryonic stem cells from a previously genetically engineered species of mice carrying a copy of human chromosome 21. They discovered that extra chromosome 21 - a genetic state known as trisomy 21 - disturbs a key regulating gene called NRSF or REST, which in turn disturbs the cascade of other genes that control normal development at the embryonic stem cell stage. Furthermore, they identified one gene (DYRK1A) on human chromosome 21, whose overdose in trisomy (DS) is responsible for the observed effects.

Down Syndrome belongs to the group of conditions called ‘aneuploidies’, defined by an abnormal loss or gain of genetic material, i.e. fragments of chromosomes or whole chromosomes. Aneuploidies cause congenital anomalies that are a prime cause of infant death in Europe and the USA, and are currently on the increase with advancing maternal age in European countries. The number of people with DS in Europe exceeds half a million. The condition is more common than muscular dystrophy and cystic fibrosis, but the development of new therapeutic concepts is hindered by the fact that unlike muscular dystrophy and cystic fibrosis, where a single mutated gene causing the disease is known, the entire human chromosome 21 (containing around 300 genes) still has to be dissected into individual gene-dose contributions to the DS symptoms.

Professor Nizetic, calling for further research into the components of the disturbed cascade he and his team have revealed said; “We hope that further research might lead to clues for the design of new therapeutic approaches tackling developmental delay, mental retardation, ageing and regeneration of brain cells, and Alzheimer’s disease. In other words, we hope our work will open new routes to tackle the genetics of these health disorders, approaching them from the “back entrance”, as dominant component-symptoms of Down Syndrome.”

The studies results may explain why kids of older dads are more likely to have some genetic disorders, and why those disorders are more common than expected…

In a cruel irony, testis cells carrying the mutation that causes Apert’s syndrome are fitter than normal cells, even though children born from sperm derived from those cells are weakened by fused fingers, toes and skulls, a new study has found.

The research, to be published in the Proceedings of the National Academy of Sciences Online Early Edition during the week of July 14-18, can explain why the syndrome is unexpectedly common, and why sperm from older men carry the mutation more frequently than expected.

The likelihood that a child from an older father inherits this and similar genetic diseases is approximately 10- to 20-fold greater than that of a younger father, yet the molecular reasons behind it have been elusive, said USC biologist Norman Arnheim, who co-led the study with USC’s Peter Calabrese.

Calabrese, Arnheim and two other USC colleagues found the strongest evidence yet that testis cells carrying the mutant gene causing Apert’s syndrome have a survival advantage over non-mutant cells. This means that as a man ages, the number of mutant cells rises exponentially, as does the sperm descended from them.

Because so much DNA is constantly being copied, small errors often occur. Apert’s syndrome is caused by one of two simple switches on a gene located in a man’s sperm.

But geneticists have puzzled over why Apert’s syndrome occurs 100 to 1000 times more often than would be expected from random, spontaneous copy errors.

Thanks to a method developed by Arnheim’s lab that divides the testis into about 200 units, the scientists observed that cells with mutated DNA are clustered in specific areas, rather than distributed evenly, as would be expected if the copy errors simply occurred more frequently.

While the researchers have seen this before, this study is the first to test both Apert’s syndrome mutations in testes from both young and old individuals in this way.

Comparing computer models with observed data, the scientists were able to demonstrate that the high frequency of the disease is not due to an increased chance of a mistake being made when the gene is copied, as has been widely proposed in the past.

Instead, the concentrated areas observed in the testes could be explained by a selective advantage of the mutant cells over non-mutant ones, meaning that mutant lineages would grow in number over time, thus increasing the chances that more sperm will contain mutant genetic material.

This seems counter-intuitive, since when we think of natural selection, we often think of beneficial traits, like a mutant butterfly with camouflaged wings, which escapes predators and passes this advantageous color to its offspring.

But in the case of Apert’s syndrome, the gene switches end up making the mutant testis cell fitter, while this is not the case in the humans who develop from the resulting sperm.

“It just seems so odd that the testis that causes such a harmful disease for the kid apparently has an advantage over cells without the mutation,” Calabrese said. While theories have been suggested, it’s not yet known what this advantage is for sure, he added.

This evolutionary explanation, which has been proposed but rarely tested, may hold true for other genetic disorders such as achondroplasia, the most common form of dwarfism, as that condition is also linked to a single gene substitution.

“I think it raises the possibility that there might be a larger class of genetic diseases that are the result of a selective advantage when the mutation occurs,” Arnheim said.

If scientists are able to pin down the molecular mechanism that enables this advantage, there could in theory be ways to counteract it, although such thinking is highly speculative, he added.

The study is also of interest since some mutations in the same genes involved in Apert’s syndrome and achondroplasia (FGFR2 and FGFR3) appear to be involved in some types of cancer. While little is known about the mechanisms behind those mutations, such information might eventually help explain the molecular basis for the advantage in the testis.

The paper’s other authors were Soo-Kyung Choi and Song-Ro Yoon. The research was funded in part by grants from the National Institute of General Medical Sciences and the Ellison Medical Research Foundation.

New data, generated by David Ornitz and colleagues, at Washington University School of Medicine, St. Louis, have indicated a crucial role for signaling pathways that involve the protein sonic hedgehog in maintaining the blood vessels that supply the mouse heart and keep it beating.  These data have implications for drug development as they suggest that antagonists of hedgehog signaling pathways, such as those being developed as anticancer therapeutics, might have unwanted side effects.

In the study, mice lacking the ability to mediate hedgehog signaling in cells that form part of the blood vessels that supply the heart were found to die of heart failure.  This was because in the absence of hedgehog signaling the blood vessels of the heart were lost, meaning that the heart cells were no longer supplied with enough oxygen and died.  Although these data indicate a need for caution when developing clinical antagonists of hedgehog signaling, it is possible that the degree of inhibition needed to have a clinical effect on tumor development might not have the effect on blood vessels of the heart that completely eliminating expression of the protein does.

Switches are a part of daily life, from snoozing your alarm, turning on the coffee maker, firing up your car engine, and so on until we turn off the lights at night. Researchers have now cataloged even more templates of possible switches within a living cell than we use throughout our day.Naren Ramakrishnan, associate professor of computer science at Virginia Tech, USA, and Upinder S. Bhalla, at the National Centre for Biological Sciences (NCBS), part of the Tata Institute of Fundamental Research in India, found that cells can make use of thousands of switches to support important biological functions.

Cells use switches for determining what kind of cell to become – skin or blood, for instance, in responding to stress, and in communication with other cells. “A switch is like a memory unit,” said Bhalla. “The state of the switch — whether it is on or off, is like a computer memory that can store a bit of 0 or 1. Although real biological switches are quite complex and regulated in many ways, we have shown the simplest possible ways in which switches could work”, Bhalla said.

The researchers report their work in the June 20 issue of the Public Library of Science (PLoS) Computational Biology, in the article “Memory Switches in Chemical Reaction Space.” Their collaboration began during a sabbatical visit by Ramakrishnan to NCBS in Bangalore, India. Ramakrishnan is a computer scientist whose expertise is in numerical simulation and data mining. Bhalla is a computational neuroscientist with broad interests in biochemical network modeling and simulation. They decided to use Virginia Tech’s System X supercomputer to search for the many ways in which cells can implement switches.

“Our exploration using System X is rather like how a tinkerer or a kid puts together things to see if they do something useful. We took a lot of ’spare parts’, each spare part being one chemical reaction, connected them together every which way, and we found that a surprising number of these artificially constructed networks actually were switches,” said Ramakrishnan.

“Popular opinion used to be that there are a small number of ways in which switches can be realized by biology, but we found thousands of switches in our search,” Ramakrishnan said.

The researchers report in PLoS Computational Biology, “We find nearly 4,500 reaction topologies, or about 10 percent of our tested configurations, that demonstrate switching behavior.”

Their research also led to a comprehensive “map” of biochemical switches. The map further revealed that most of the switches form a “family” – that is, the switches are all related to one another. “This has important implications since it suggests how evolution might stumble upon a switch rather easily.” Ramakrishnan said.

“Of course, there is more to cells than switches,” Bhalla said. “But switching and memory are the most basic behaviors possible. Armed with our catalog of switches, we can now proceed to investigate more interesting behaviors like complex information processing.”

Developing techniques to image the complex biological systems found at the sub-cellular level has traditionally been hampered by divisions between the academic fields of biology and physics. However, a new interdisciplinary zeal has seen a number of exciting advances in super-resolution imaging technologies.

In the June issue of Physics World, Paul O’Shea, a biophysicist at the University of Nottingham, Michael Somekh, an optical engineer at Nottingham’s Institute of Biophysics, Imaging & Optical Science, and William Barnes, professor of photonics at the University of Exeter, outline these new techniques and explore why their development is an endeavour that requires the best efforts of both biologists and physicists.

The traditional division between the disciplines has found common ground in the effort to image cellular functions. While some living cells are larger than 80 micrometres across, important and interesting cellular processes - such as signalling between cells - can take place at length scales of less than one micrometre.

This poses serious challenges for traditional imaging techniques such as fluorescence microscopy, whereby optical microscopes are used to observe biological structures that have been tagged with fluorescent molecules that emit photons when irradiated with light of a specific wavelength, as these offer a resolution of at best 200 nanometres. Increasingly, biologists have turned to physicists for help in breaking through this “diffraction” limit.

The result has been the development in recent years of several novel techniques to extend the reach of fluorescence microscopy. These include methods such as stimulated emission depletion microscopy (STED), stochastic reconstruction microscopy (STORM), photo-activated localization microscopy (PALM) and structured illumination microscopy, all of which are capable of resolving structures as small as 50 nanometres across. These techniques build on theoretical and experimental tools common to physics that allow the physical diffraction limits of light to be broken.

As the authors of the article explain, “What is fascinating is that the experimental needs of biology are driving developments in imaging technology, while advances in imaging technology are in turn inspiring new biological questions. Many of these developments are also going hand in hand with a revolution that is taking place in biological thinking, which intimately involves physicists.”

Researchers at Duke University Medical Center have uncovered definitive evidence that a small but potent subset of immune system B cells is able to regulate inflammation.Using a new set of scientific tools to identify and count these cells, the team showed that these B cells can block contact hypersensitivity, the type of skin reactions that many people have when they brush against poison ivy.

The findings may have large implications for scientists and physicians who develop vaccines and study immune-linked diseases, including cancer. Once the cells that regulate inflammatory responses are identified, scientists may have a better way to develop treatments for many diseases, particularly autoimmune diseases such as arthritis, type 1 diabetes and multiple sclerosis.

“While the study of regulatory T cells is a hot area with obvious clinical applications, everyone has been pretty skeptical about whether regulatory B cells exist,” said Thomas F. Tedder, Ph.D., chairman of the Immunology Department and lead author of the study published in the May issue of Immunity. “I am converted. They do exist.”

Koichi Yanaba and Jean-David Bouaziz identified this unique subset of small white blood cells, which they call B10 cells, in the Tedder laboratory.

The researchers found that B10 cells produce a potent cytokine, called IL-10 (interleukin-10), a protein that can inhibit immune responses. The B10 cells also can affect the function of T cells, which are immune system cells that generally boost immune responses by producing cytokines. T cells also attack tumors and virus-infected cells.

The study was supported by grants from the NIH, the Association pour la Recherche contre le Cancer (ARC), Foundation Rene Touraine, and the Philippe Foundation.

Depleting B10 cells may enhance some immune responses, Tedder said. Enhancing B10 cell function may inhibit inflammation and immune responses in other diseases, like contact hypersensitivity.

“Now that we have been able to identify this regulatory B cell subset, we have already developed treatments that deplete these cells in mice. We are moving to translate these findings to benefit people,” he said.

“The discovery of the ability to identify this potent regulatory cell type should provide important clues to how the immune system regulates itself in response to vaccines as well as infectious agents,” says Barton F. Haynes, M.D., leader of the international Center for HIV/AIDS Vaccine Immunology (CHAVI), a consortium of universities and academic medical centers, and director of the Duke Human Vaccine Institute. “This information should enable researchers to design ways to help the immune system control infections more effectively, and could be a useful advance as we refine approaches to preventing HIV infection.”

There’s a huge initiative underway to look at regulatory T cells in autoimmune disease, HIV infection, and cancer therapy,” Tedder said. “What we have also shown is that it is not only regulatory T cells, but also regulatory B cells that could prevent a person from making effective immune responses in HIV and many other diseases, particularly cancer.”

The Duke researchers developed a way to mark the B10 cells so that they could see that just these cells were producing IL-10. Previously, scientists could only purify a population of B cells and see whether IL-10 could be produced by some of these cells in the population.

In this study, they found that the B10 cells represented only 1-2 percent of all of the B cells in the spleen of a normal mouse. Before this, no one had definitively identified this B cell subset or such regulatory B cells in normal mice, although B cell regulatory function had been described in some genetically altered mice with chronic inflammation.

“In this study, we could directly look at the B cells that were producing IL-10, and figure out what their cell surface molecules looked like, so that we could isolate them. This allowed us to show that this rare subset of B cells controlled immune responses by producing IL-10, which inhibits T cell inflammatory responses,” Tedder said.

The scientists studied a special mouse (CD19-deficient) with altered genes that give them an increased contact hypersensitivity reaction. As it turned out, these mice lacked B10 cells, which resulted in exaggerated inflammation reaction. “This allowed us to show that giving CD19-deficient mice a few B10 cells had a big effect on reducing inflammation,” Tedder said.

They found that depleting all B cells in the mice also resulted in worse inflammation. Since total B cell depletion therapies are now being used to treat people with B cell cancers and autoimmune disease, these findings help to further explain how these therapies treat disease. They also open the door to creating new therapies that take advantage of the power of B10 cells.

This is the first of several papers that will describe cases in which regulatory B10 cells help control immune responses, Tedder said.

With improved resolution, tissue-specific molecular markers and precise timing, University of Oregon biologist James A. Weston and colleagues have possibly overturned a long-standing assumption about the origin of embryonic cells that give rise to connective and skeletal tissues that form the base of the skull and facial structures in back-boned creatures from fish to humans.

Weston and co-authors from the Max Planck Institute of Immunology in Germany and the French National Scientific Research Centre at the Curie Institute document their potentially textbook-changing case in an article appearing online this week (May 19-23) ahead of regular publication in the Proceedings of the National Academy of Sciences.

The cells in question, they argue, do not come from a portion of embryonic neural epithelium called the neural crest, as widely believed, but rather from a distinct thin layer of epidermal epithelial cells next to it. “Our results,” Weston said, “could lead to a better understanding of the etiology of craniofacial defects, as well as the evolution of the head that distinguishes vertebrates from other creatures.”

The neural crest was first identified by classical embryologists in the late 19th and early 20th centuries and has been one of the most studied embryonic tissues. Conventional wisdom says that the neural crest gives rise to skeletal and connective tissue of the head and face, as well as a wide diversity of other stem cells that migrate to many places in the vertebrate embryo, where they spawn the cells that create the peripheral nervous system, and pigment cells in skin and hair (or scales and feathers).

The new study is part of research done over 25 years in Weston’s quest to understand early development of the neural crest and explore alternative explanations for sometimes differing findings involving its assumed cell lineages. Weston noted that mutations in mice that adversely affected development of the peripheral nervous system or pigmentation did not affect craniofacial structures, whereas mutations that caused abnormal development of skeletal and connective tissue of the head and face did not alter neural crest-derived pigment or peripheral nervous system cells.

This paradox, he said, led him to wonder if different genetic programs were required to function in distinct embryonic precursors of these tissues. “In our new paper,” he said, “we finally were able to re-examine some of the underlying assumptions that have led to the conventional wisdom about the source of the embryonic cell lineages that give rise to the skeleton and connective tissue of the head and face.”

In the mouse embryo at eight days gestation, Weston and collaborators used high-resolution imaging and immunostaining techniques to identify and track the dispersal of cells known to jump start connective and skeletal tissue development. They were able to see clearly that these cells came from the non-neural layer of cells rather than from the neural crest. The same distinction also exists in chicken embryos during the first few days of gestation, Weston noted. “Looking at the right time is very important,” he said.

Weston argues that this non-neural epithelium is indeed distinct from the neural crest, because its cells contain characteristically different molecules. He and colleagues dispute suggestions that this non-neural structure is simply a sub-domain of the neural crest. “These cells emerge at a different time in development and disperse in the embryo before neural crest cells begin to migrate,” Weston said.

“New technologies let us see cell types more clearly than ever before,” said Weston, a member of the UO’s Institute of Neuroscience. “We previously had discovered that a molecule that marks cell surfaces in the non-neural epithelium reveals a very sharp boundary between this non-neural epithelium and the neural tissue connected to the neural crest. In this study, we took a closer look.”

They located a population of cells in the non-neural epithelium that express other molecules that “do not appear to originate from the neural crest,” said Weston, who retired in 2001 but continued to teach in the College of Arts and Sciences until 2006. He still collaborates in some research with colleagues at the UO and at various labs around the world.

“I think our results have two important messages,” he said. “First, it is important to identify and validate — rather than ignore — assumptions; and second, because we identified an alternative embryonic cell lineage as the source of the head and facial structures, we can now more effectively analyze and understand the molecular-genetic mechanisms that regulate the normal and abnormal development of these structures.”

Researchers from the University of Melbourne, Australia, and the University of Texas, USA, have extracted genes from the extinct Tasmanian tiger (thylacine), inserted it into a mouse and observed a biological function – this is a world first for the use of the DNA of an extinct species to induce a functional response in another living organism.

The results, published in the international scientific journal PLoS ONE this week, showed that the thylacine Col2a1 gene has a similar function in developing cartilage and bone development as the Col2a1 gene does in the mouse.

“This is the first time that DNA from an extinct species has been used to induce a functional response in another living organism,” said Dr Andrew Pask, RD Wright Fellow at the University of Melbourne’s Department of Zoology who led the research.

“As more and more species of animals become extinct, we are continuing to lose critical knowledge of gene function and their potential.”

“Up until now we have only been able to examine gene sequences from extinct animals. This research was developed to go one step further to examine extinct gene function in a whole organism,” he said.

“This research has enormous potential for many applications including the development of new biomedicines and gaining a better understanding of the biology of extinct animals,” said Professor Richard Behringer, Deputy Head of the Department of Molecular Genetics, M.D. Anderson Cancer Center, at the University of Texas, who is the corresponding author on the paper.

The last known Tasmanian tiger died in captivity in the Hobart Zoo in 1936. This enigmatic marsupial carnivore was hunted to extinction in the wild in the early 1900s.

Researchers say fortunately some thylacine pouch young and adult tissues were preserved in alcohol in several museum collections around the world.

The research team used thylacine specimens from Museum Victoria in Melbourne Australia to examine how the thylacine genome functioned.

The research team isolated DNA from 100 year old ethanol fixed specimens. After authenticating this DNA as truly thylacine, it was inserted into mouse embryos and its function examined.

The thylacine DNA was resurrected, showing a function in the developing mouse cartilage, which will later form the bone.

“At a time when extinction rates are increasing at an alarming rate, especially of mammals, this research discovery is critical,” says Professor Marilyn Renfree, Federation Fellow and Laureate Professor in the University of Melbourne’s Department of Zoology, the senior author on the paper.

“For those species that have already become extinct, our method shows that access to their genetic biodiversity may not be completely lost.”

The ability to drive somatic, or fully differentiated, human cells back to a pluripotent or “stem cell” state would overcome many of the significant scientific and social challenges to the use of embryo-derived stem cells and help realize the promise of regenerative medicine. Recent research with mouse and human cells has demonstrated that such a transformation (“reprogramming”) is possible, although the current process is inefficient and, when it does work, poorly understood. But now, thanks to the application of powerful new integrative genomic tools, a cross-disciplinary research team from Harvard University, Whitehead Institute, and the Broad Institute of MIT and Harvard has uncovered significant new information about the molecular changes that underlie the direct reprogramming process. Their findings are published online in the journal Nature.

“We used a genomic approach to identify key obstacles to the reprogramming process and to understand why most cells fail to reprogram,” said Alexander Meissner, assistant professor at Harvard University’s Department of Stem Cell and Regenerative Biology and associate member of the Broad Institute, who led the multi-institutional effort. “Currently, reprogramming requires infecting somatic cells with engineered viruses. This approach may be unsuitable for generating stem cells that can be used in regenerative medicine. Our work provides critical insights that might ultimately lead to a more refined approach.”

Previous work had demonstrated that four transcription factors — proteins that mediate whether their target genes are turned on or off — could drive fully differentiated cells, such as skin or blood cells, into a stem cell-like state, known as induced pluripotent stem (iPS) cells. Building off of this knowledge, the researchers examined both successfully and unsuccessfully reprogrammed cells to better understand the complex process.

“Interestingly, the response of most cells appears to be activation of normal ‘fail safe’ mechanisms”, said Tarjei Mikkelsen, a graduate student at the Broad Institute and first author of the Nature paper. ”Improving the low efficiency of the reprogramming process will require circumventing these mechanisms without disabling them permanently.”

The researchers used next-generation sequencing technologies to generate genome-wide maps of epigenetic modifications — which control how DNA is packaged and accessed within cells — and integrated this approach with gene expression profiling to monitor how cells change during the reprogramming process. Their key findings include:

1. Fully reprogrammed cells, or iPS cells, demonstrate gene expression and epigenetic modifications that are strikingly similar, although not necessarily identical, to embryonic stem cells.
2. Cells that escape their initial fail-safe mechanisms can still become ‘stuck’ in partially reprogrammed states.
3. By identifying characteristic differences in the epigenetic maps and expression profiles of these partially reprogrammed cells, the researchers designed treatments using chemicals or RNA interference (RNAi) that were sufficient to drive them to a fully reprogrammed state.
4. One of these treatments, involving the chemotherapeutic 5-azacytidine, could improve the overall efficiency of the reprogramming process by several hundred percent.

“A key advance facilitating this work was the isolation of partially reprogrammed cells,” said co-author Jacob Hanna, a postdoctoral fellow at the Whitehead Institute, who recently led two other independent reprogramming studies. “We expect that further characterization of partially programmed cells, along with the discovery and use of other small molecules, will make cellular reprogramming even more efficient and eventually safe for use in regenerative medicine.”

Significant numbers of female high school athletes and non-athletes suffer from one or more components of the female athlete triad, a combination of three conditions that can lead to cardiovascular disease, according to a new study by Medical College of Wisconsin researchers in Milwaukee.

The study results were presented today at the American College of Sports Medicine at Indianapolis, by Anne Z. Hoch, D.O., associate professor of orthopedic surgery and physical medicine and rehabilitation at the Medical College, and director of the Froedtert & Medical College Sports Medicine Program. She is also a member of the Medical College’s Cardiovascular Center.

Dr. Hoch found that 78 percent of female high school athletes and 65 percent of female high school non-athletes display one or more components of the female athlete triad. The triad is a combination of three conditions – low energy availability, menstrual abnormalities and low bone mineral density – that often leads to the same steroid and hormonal profiles as postmenopausal women.

“We are concerned that non athletic girls have some of the same components of the female athlete triad as athletes and are in fact at greater risk for low bone density,” says Dr. Hoch. “These young women are under great pressure to conform to society’s standards of body image. In an effort to lose weight, they are restricting their caloric intake and adapting unhealthy nutrition habits.”

The study, conducted at Froedtert Hospital, examined eighty varsity athletes and eighty non-athletes at an all-girls school in Milwaukee. Ninety-three percent of non-athletes were found to have calcium deficiencies, compared to 74 percent of athletes.

“Most important and alarming is that 30 percent of the non athletes versus 16 percent of athletes were found to have low bone mineral density putting them at greater risk for developing osteoporosis earlier in life,” says Dr. Hoch.

Both groups showed little difference in low energy availability, with 39 percent of non-athletes and 36 percent of athletes reporting this condition. The athletes reported 33 percent more menstrual abnormalities than the non-athletes. Women who have normal periods, and hence normal estrogen levels, are less likely to display changes in the function of the layer of cells that line the interior of blood vessels, called the endothelium.

“Change in endothelial function is the seminal event in cardiovascular disease,” says Dr. Hoch.

Dr. Hoch began her studies in the late 1990s to see if young women who have menstrual abnormalities as a result of participating in intense sports are likely to develop cardiovascular disease similar to that seen in postmenopausal women. She and her colleagues were able to show that young women who had the triad also had early vascular change that is a precursor to cardiovascular disease.

“We not only need to educate athletes about the consequences of the triad, now we must educate all students about the harmful effects of a restrictive diet in the adolescent period,” says Dr. Hoch.

UC San Diego study finds mice can sense oxygen through skin

Biologists at the University of California, San Diego have discovered that the skin of mice can sense low levels of oxygen and regulate the production of erythropoietin, or EPO, the hormone that stimulates our bodies to produce red blood cells and allows us to adapt to high-altitude, low-oxygen environments.

Their surprising finding, published in the April 18th issue of the journal Cell, contradicts the notion of mammalian skin as an envelope around our bodies with little connection to the respiratory system.

If found to apply to humans, the discovery could radically change the way physicians treat anemia and other diseases that require boosting our bodies’ ability to produce red blood cells.  It also could be used to improve the performance of endurance athletes competing in this summer’s Olympic Games.

“What we found in this study is really something quite unusual,” said Randall Johnson, a professor of biology at UC San Diego who headed the research study.  “We discovered that mammalian skin, at least in mice, responds to how much oxygen is above it and, by virtue of that response, changes blood flow through the skin.  This, in turn, changes one of the most basic responses to low oxygen that we have, which is the production of erythropoietin.”

Those responses, the researchers suspect, could be ancient traits retained as mammals evolved from lower forms of vertebrates, such as amphibians, that possess the same sorts of ion channels to promote oxygen diffusion in their extremely permeable skins as mammals have in their lungs.

“Amphibians—frogs most notably—breathe through their skin and are able to sense and respond to how much oxygen is in the air or water around their skin,” Johnson added.  “But nobody had ever thought about asking those questions about the skin of mammals.”

“From an evolutionary point of view, the results make sense, considering the important role of the skin for oxygen uptake in amphibians,” said Frank Powell, a professor of medicine at UCSD and expert in human and animal adaptations to high-altitude environments who was part of the team.  “It will be very interesting to see how these mechanisms work in humans and if, for example, different oxygen levels at the skin could affect how rapidly and how well one adapts to low oxygen in the intensive care unit of a hospital or at high altitude.”

The UC San Diego team found no evidence that mice could breathe through their skin.  But if their discovery that mice sense low oxygen through their skin and trigger EPO production is found to apply to humans, it would have dramatic implications for the training and testing of endurance athletes during the Summer Olympic Games in Beijing.

Besides training at altitude and in low-oxygen tents—the two generally accepted legal methods of boosting red blood cell production–runners, swimmers, cyclists and other endurance athletes seeking better performances by increasing the oxygen-carrying capacity of their blood may now have another legitimate way to increase their red blood counts.  Blood doping, the injection of additional red blood cells into the body, and the injection of synthetic recombinant EPO to boost red blood cell production are illegal in the Olympics and banned by most sports governing bodies.  But what if athletes could boost their own EPO and red blood cell counts by exposing their bodies to low levels of oxygen” Or, to obtain the same effect, by merely increasing blood flow through their skin”

“We’ve discovered a potent physiological trigger that can be enacted or enabled without exogenous sources of EPO,” said Johnson.  “We show in this paper that breathing in one level of oxygen and exposing your body to another level of oxygen is really a potent trigger for the body to produce its own EPO.  It’s not hard to foresee people taking what we’ve learned in mice and applying it to humans.”

If human skin is found to be sensitive to oxygen levels, it could revive the debate over the “Goldfinger Syndrome.” This idea, perpetuated by the famous James Bond movie in which the villain’s girlfriend is killed after being painted gold, has been the focus of urban legends and internet discussions about the possible negative health effects of painting the skin.  It has been the subject of two investigations by the Discovery Channel show “MythBusters.”

The team’s discovery—aided by collaborators in Sweden, Germany and the University of Pennsylvania—came after two years of trying to determine why certain mice the researchers had genetically engineered for experiments exhibited high levels of EPO.  In 2004, Johnson and his students published a paper in the journal Plos Biology, detailing how they had transformed ordinary laboratory mice into the rodent equivalent of Olympic endurance athletes.  They did this by deleting a gene that allows mammalian muscles to switch from aerobic to anaerobic metabolism when oxygen levels in the muscle run low.

Most of our daily activities are performed aerobically, through biochemical mechanisms in our muscles that make full use of oxygen.  But when the demands of our muscular system exceed its available supply of oxygen, as in sprinting for a bus or lifting a heavy object, a protein known as hypoxia inducible transcription factor-1, or HIF-1, is activated.  This protein enables the muscle to switch to the more energetically explosive, but expensive anaerobic process, which does not use oxygen and generates lactic acid as its byproduct.

When Johnson and students knocked out the negative regulator of the HIF-1 gene, they produced tiny mice with skin that look red and flushed.  These mice have trouble retaining body heat because a larger proportion of their blood is sent to their skin and cooled, much like a person sitting in a hot sauna or Jacuzzi.  But the most puzzling aspect of these mutant mice is their extremely high EPO levels—so high that 90 percent of their blood plasma is composed of red blood cells, compared to 40 to 50 percent for normal individuals.

“Their blood is basically paste and their hearts are enlarged as a result,” Johnson said.  “We could not understand why the skin was exerting this effect.  It just didn’t make sense to us.  We could figure out every other aspect of why this mutant mouse looked an acted the way it did, but this one thing was really bothersome to us, so that sent us down this road.  When we found that the EPO was coming from internal organs, not the skin of these mice, we thought there must be some kind of signal from the skin to the internal organs.”

Johnson and others in his laboratory—graduate student Adam Boutin, postdoctoral fellow Alexander Weidemann and undergraduate Lernik Mesropian—verified that the HIF-1 gene was responsible by genetically engineering mutant mice without the gene in their skin cells.  These mice were unable to signal the production of extra EPO when their skin was exposed a chamber filled with 10 percent oxygen—about the level found at Mount Everest.  The concentration of oxygen at sea level is about 21 percent.  Normal mice were able to increase the amount of EPO production at this 10 percent level.

This occurred, the researchers found, when more blood rushed into the skin.  By putting on the mouse’s skin a nitroglycerine patch, which increases blood flow through the skin, the researchers found that mice could dramatically increase their production of EPO and red blood cells.

“EPO administration is a multi-billion dollar drug market for the treatment of all sorts of diseases involving low red blood cell counts,” said Johnson.  “So the ability to manipulate red blood cell production just by changing blood flow through certain parts of the skin could be profound.  We show in this study that by just putting a little nitroglycerine patch we were able to trigger very big increases in EPO.  Whether this turns out to be true for humans, we don’t know yet.  But potentially this could be a very interesting way to manipulate this pathway.”

Johnson and his team, which included UCSD assistant professor of biology Colin Jamora, found that having mice breathe in a chamber with their entire bodies exposed to low levels of oxygen had the greatest response and produced the most EPO.  When the mice were allowed to breathe 10 percent oxygen in one chamber, but had the skin from their neck down exposed to 21 percent, or sea-level oxygen, in another chamber built by Powell, more than one-half of their adaptation to low oxygen was lost.

“If we put mice that lack a hypoxic response in their skin in a low oxygen chamber more than half of their hypoxic response goes away and that was surprising to us,” Johnson said.  “The skin really is a big contributor to the way the mouse responds to low oxygen.”

“All of the important responses to hypoxia, or low oxygen, were thought to be triggered by oxygen-sensitive nerves and molecules in the blood and internal organs,” said Powell.  “However, these experiments clearly show that the skin directly responds to changes in oxygen in the environment with changes in blood flow.  These changes in skin blood flow are highly significant by causing changes in the levels of hypoxic inducible factor, which is a sort of ‘master switch’ for adapting to low oxygen that activates multiple genes to enhance oxygen delivery throughout the body.”

Johnson said that because people with skin inflammations such as psoriasis and eczema can have low red blood cell counts, he and his team are interested in extending their study to investigate anemia caused by skin inflammations in their mutant mice.

“In people with anemia of inflammation it seems as if the EPO isn’t having an effect,” he added.  “We actually have mutant mice with skin inflammation that show this same effect.  They have high EPO levels, but they don’t have a high red blood cell count.  The mutants we used in our study have high EPO levels and high red blood cell counts.  But they don’t have inflammation.  The next step for us is going to be trying to figure out why these inflammatory diseases trigger EPO.  Is there something about inflammation that we can trigger so these people can be treated without suffering this kind of anemia””

The scientists said in their paper that their discovery also might explain why people in some parts of Nepal, India and Pakistan massage newborn babies in mustard oil, a mild irritant that promotes blood flow through the skin.

“We show in this study that if you paint the skin of a mouse with this mild irritant, mustard oil, it will also trigger EPO release at a somewhat lower level,” Johnson said.  “In India and Pakistan babies are in some communities massaged in mustard oil at birth; and some health workers have been trying to get them to stop this folk tradition.  But we show that in mice this increases EPO levels.  And since increased EPO levels contribute to increased red blood cell counts one could imagine it being beneficial.”