Category Archives: Transhuman News

Duke Medicine researchers have shown how gene mutations may cause common forms of cartilage tumors.

In a study published in the Feb. 16, 2015, issue of the Proceedings of the National Academy of Sciences, Duke researchers and their colleagues revealed that mutations in the isocitrate dehydrogenase (IDH) gene contribute to the formation of benign tumors in cartilage that can be a precursor to malignancies.

These benign tumors, known as enchondromas, are associated with severe pain, fractures, and skeletal deformities. They also have the potential to evolve into a cancerous form known as chondrosarcomas. Over 40% of primary bone cancers are chondrosarcomas, according to the American Cancer Society.

"These findings are important for cancer treatments, as currently there are no drug therapies for enchondromas and there are no universally effective chemotherapies for chondrosarcomas," said senior author Benjamin Alman, M.D., chair of the Orthopaedic Surgery Department at Duke University Medical Center.

All bones begin as cartilage tissue, and some of this tissue becomes growth-plate cartilage, which is responsible for bone growth. Over time, the growth-plate cells become replaced with bone. When development is complete, only the joint cartilage at the tips of the bone typically remains.

"About five percent of people have some kind of cartilage tumor in their bones, and in most cases it's because the growth-plate cartilage cells weren't fully replaced by bone tissue," Alman said. "Our study sought to understand what happens to make those growth-plate cartilage cells remain, and this work will ultimately be used to determine what causes those benign tumors to become malignant."

The researchers identified a broad range of mutations in the IDH gene in cartilage tumors. They used mice and cartilage cells in a dish to study one mutant form of IDH that is identified only in cartilage cells. They found that mutations in the IDH gene alter the way cartilage cells function during bone formation, leaving some cells behind. This is apparently what leads to enchondromas.

Previous work on cartilage tumors has been done using models based on genetic mutations that occurred only rarely in enchondromas; however, IDH mutations are present in a high percentage of enchondromas.

The researchers hope these findings will aid in developing new treatments by using animal models that more closely represent the types of mutations apparent in the vast majority of patients with enchrondromas.

For instance, the study provides evidence that drugs designed to block the function of IDH might be useful in treating benign cartilage tumors to possibly prevent their transformation to malignancy.

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Gene mutation drives cartilage tumor formation

Investigators with the National Institutes of Health have discovered the genomic switches of a blood cell key to regulating the human immune system. The findings, published in Nature today, open the door to new research and development in drugs and personalized medicine to help those with autoimmune disorders such as inflammatory bowel disease or rheumatoid arthritis.

The senior author of the paper, John J. O'Shea, M.D., is the scientific director at NIH's National Institute of Arthritis and Musculoskeletal and Skin Diseases. The lead author, Golnaz Vahedi, Ph.D., is a postdoctoral fellow in Dr. O'Shea's lab in the Molecular Immunology and Inflammation Branch. The study was performed in collaboration with investigators led by NIH Director, Francis S. Collins, M.D., Ph.D., in the Medical Genomics and Metabolic Genetics Branch at the National Human Genome Research Institute.

Autoimmune diseases occur when the immune system mistakenly attacks its own cells, causing inflammation. Different tissues are affected in different diseases, for example, the joints become swollen and inflamed in rheumatoid arthritis, and the brain and spinal cord are damaged in multiple sclerosis. The causes of these diseases are not well understood, but scientists believe that they have a genetic component because they often run in families.

"We now know more about the genetics of autoimmune diseases," said NIAMS Director Stephen I. Katz, M.D., Ph.D. "Knowledge of the genetic risk factors helps us assess a person's susceptibility to disease. With further research on the associated biological mechanisms, it could eventually enable physicians to tailor treatments to each individual."

Identifying autoimmune disease susceptibility genes can be a challenge because in most cases a complex mix of genetic and environmental factors is involved. Genetic studies have shown that people with autoimmune diseases possess unique genetic variants, but most of the alterations are found in regions of the DNA that do not carry genes. Scientists have suspected that the variants are in DNA elements called enhancers, which act like switches to control gene activities.

Dr. O'Shea's team wondered if the alterations might lie in a newly discovered type of enhancer called a super-enhancer (SE). Earlier work in the laboratory of Dr. Collins and others had shown that SEs are especially powerful switches, and that they control genes important for the function and identity of each individual cell type. In addition, a large number of disease-associated genetic alterations were found to fall within SEs, suggesting that disease occurs when these switches malfunction.

Dr. O'Shea's team began by searching for SEs in T cells, immune cells known to play an important role in rheumatoid arthritis. They reasoned that SEs could serve as signposts to steer them toward potential genetic risk factors for the disease.

"Rather than starting off by looking at genes that we already knew were important in T cells, we took an unbiased approach," said Dr. O'Shea. "From the locations of their super-enhancers, T cells are telling us where in the genome these cells invest their assets--their key proteins--and thereby where we are most likely to find genetic alterations that confer disease susceptibility."

Using genomic techniques, the researchers combed the T cell genome for regions that are particularly accessible to proteins, a hallmark of DNA segments that carry SEs. They identified several hundred, and further analysis showed that they largely control the activities of genes that encode cytokine and cytokine receptors. These types of molecules are important for T cell function because they enable them to communicate with other cells and to mount an immune response.

But the researchers' most striking observation was that a large fraction of previously identified alterations associated with rheumatoid arthritis and other autoimmune diseases localized to these T cell SEs. Additional experiments provided further evidence for a central role for SEs in rheumatoid arthritis. When the scientists exposed human T cells to a drug used to treat the disease, tofacitinib, the activities of genes controlled by SEs were profoundly affected compared to other genes without SEs. This result suggests that tofacitinib may bring about its therapeutic effects in part by acting on SEs to alter the activities of important T cell genes.

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Link between powerful gene regulatory elements and autoimmune diseases

23 hours ago by Amanda Siegfried Dr. Leonidas Bleris (left), assistant professor of bioengineering at UT Dallas,and Richard Taplin Moore MS11 helped create a new delivery system that may change gene therapy.

Bioengineers at The University of Texas at Dallas have created a novel gene-delivery system that shuttles a gene into a cell, but only for a temporary stay, providing a potential new gene-therapy strategy for treating disease.

The approach offers distinct advantages over other types of gene therapies under investigation, said Richard Taplin Moore MS'11, a doctoral student in bioengineering in the Erik Jonsson School of Engineering and Computer Science. He is lead author of a study describing the new technique in the Jan. 30 issue of the journal Nucleic Acids Research.

"In other gene therapy approaches, the therapeutic genetic messages being delivered can persist for a long time in the patient, potentially lasting for the patient's entire lifetime," Moore said. "This irreversibility is one reason gene therapies are so difficult to get approved."

The UT Dallas study describes proof-of-concept experiments in which a gene carrying instructions for making a particular protein is ordered to self-destruct once the cell has "read" the instructions and made a certain quantity of the protein. In its experiments with isolated human kidney cells, the research team successfully deliveredand then destroyeda test gene that makes a red fluorescent protein.

More research is needed to determine whether and how well the system might work in living organisms. But Moore said the ultimate goal is to refine the method to deliver genes that produce therapeutic proteins or drugs. The nature of the gene delivery system offers more control over how much protein the gene produces in cells or tissues. Because it does not alter the cell permanently, the method also sidesteps potential health problems that can occur if a gene is delivered to the wrong place in a cell's genome.

"Our goal was to create a delivery system for therapeutic genes that would self-destruct, giving us more control over the delivered DNA by limiting the time it resides in cells," Moore said.

Located in the nucleus of each human cell, genes are made of DNA and contain instructions for making proteins. Machinery inside each cell "reads" the instructions and builds those proteins, which then carry out various functions needed to sustain life. Defective or mutated genes can result in malfunctioning or missing proteins, leading to disease.

Gene therapy aims to replace defective genes with healthy versions. Typically the good genes are packaged with a delivery mechanism called a vector, which transports the genetic material inside cells. With traditional approaches, once in the cell, the gene permanently integrates itself into the cell's DNA.

Although promising, this type of gene therapy also has risks. If a therapeutic gene is inserted in the wrong place in the cell's DNA, such as too close to a cancer-related gene, the process could activate additional disease-causing genes, resulting in lifelong health problems for the patient. While many gene therapy clinical trials are underway worldwide, the Food and Drug Administration has not approved for sale any human gene therapy product in the U.S.

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Synthetic biology yields new approach to gene therapy