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Archive - Oct 12, 2009

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RNA Repair System Discovered in Bacteria

In new papers appearing in Science and PNAS, University of Illinois biochemistry professor Dr. Raven H. Huang and colleagues describe the first RNA repair system to be discovered in bacteria. This is only the second RNA repair system discovered to date (with two proteins from T4 phage, a virus that attacks bacteria, as the first). The novelty of the newly discovered bacterial RNA repair system is that, before the damaged RNA is sealed, a methyl group is added to the two-prime hydroxyl group at the cleavage site of the damaged RNA, making it impossible to cleave the site again. Thus, the repaired RNA is "better than new." This discovery has implications for protecting cells against ribotoxins, a class of toxins that kills cells by cleaving essential RNAs involved in protein translation. Because the enzyme responsible for methylation in the newly-discovered RNA repair system is the Hen1 homolog in bacteria, the finding also has implications for the understanding of RNA interference and gene expression in plants, animals, and other eukaryotes. The eukaryotic Hen1 is one of three enzymes (along with Dicer and Argonaute) essential for the generation of small noncoding RNAs of 19-30 nucleotides in RNA interference. The new papers appear in the October 9 issue of Science and the October 12 online edition of PNAS. [Press release] [Science abstract] [PNAS abstract]

Higher Urate Levels May Slow Progression of Parkinson's

Individuals with Parkinson's disease who have higher levels of the antioxidant urate in their blood and cerebrospinal fluid appear to have a slower rate of disease progression, according to results of a new study funded, in part, by the National Institutes of Health. The results support similar findings of an earlier, 2008 study. Urate is a chemical that at very high levels is associated with gout. A clinical trial is under way to examine the safety and potential benefits of supplemental urate elevation for recently diagnosed Parkinson's patients who have low urate levels. Experts emphasize there is no proof that elevating urate levels will help against Parkinson's disease, and that it should not be attempted outside of a clinical trial, where physicians can closely monitor possible benefits and risks, such as gout and heart disease. In the new study, investigators demonstrated the link with urate by mining a repository of clinical data and tissue samples collected from Parkinson's patients more than 20 years ago as part of a pioneering study called DATATOP, funded by the NIH's National Institute of Neurological Disorders and Stroke (NINDS). The new study was funded primarily by the NINDS, with additional support from the Department of Defense and private organizations. "This study speaks to the value of saving data and biospecimens from large clinical studies, and making them available to the research community to pursue new, unanticipated ideas," said Dr. Michael Schwarzschild, of Massachusetts General Hospital in Boston, senior author of the study. "These results were critically important. Only now we can be reasonably sure that the slower rate of progression in patients with higher concentrations of urate is real and not a chance occurrence," said Dr. Alberto Ascherio of the Harvard School of Public Health and lead author of the study.