A new study casts doubt on a theory long about what goes wrong in the brain of patients with Huntington's disease . The findings suggest new approaches to drug design against the fatal neurological disorder.
The Huntington's patients have a mutated form of a protein called huntingtin, which contains between 36 and 0 repetitions of glutamine, an amino acid, where the unaffected individuals have just a couple of dozen repeats. Scientists have long assumed that the trouble arose from the interaction of huntingtin and called caspases, enzymes involved in the degradation of proteins routine. When caspase cut small peptides of mutant huntingtin region, they thought, peptides accumulated in abnormal blood cells observed in neurons of victims of Huntington. In laboratory experiments, the same peptides kill nerve cells.
But in the online issue on October 15 Nature Genetics , geneticists Roy Dyer and Cynthia McMurray at the Mayo Clinic in Rochester, Minn., Report that the theory does not stand up to the scrutiny. When they stained brain samples from victims of human Huntington, they found that the globs features include full-length mutant huntingtin, instead of peptide fragments of the mutant. Then, they showed that caspases not cut the peptides of the mutant protein at all. Instead, caspases normal huntingtin protein break down, as they are supposed to. Things go wrong when these fragments are attracted to the abnormal huntingtin balls, instead of being processed further. The researchers believe that this interaction ultimately kills the cell, but they are not sure how.
The study is "very important" and shows that the prevailing explanation for the origin of Huntington's disease needs to be "redesigned," said Scott Zeitlin, a neuroscientist at the University . of Virginia in Charlottesville Zeitlin said the study may also help scientists find new targets for drugs against Huntington -. Such as compounds that block agglutination of the abnormal huntingtin
Sites Related
Cynthia McMurray home
Disease Huntington Society of America
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