A growing number of human neurodegenerative diseases result from the expansion of a glutamine repeat in the protein that causes the disease. Spinocerebellar ataxia type 1 (SCA1) is one such disease-caused by expansion of a polyglutamine tract in the protein ataxin-1. To elucidate the genetic pathways and molecular mechanisms underlying neuronal degeneration in this group of diseases, we have created a model system for SCA1 by expressing the full-length human SCA1 gene in Drosophila. Here we show that high levels of wild-type ataxin-1 can cause degenerative phenotypes similar to those caused by the expanded protein. We conducted genetic screens to identify genes that modify SCA1-induced neurodegeneration. Several modifiers highlight the role of protein folding and protein clearance in the development of SCA1. Furthermore, new mechanisms of polyglutamine pathogenesis were revealed by the discovery of modifiers that are involved in RNA processing, transcriptional regulation and cellular detoxification. These findings may be relevant to the treatment of polyglutamine diseases and, perhaps, to other neurodegenerative diseases, such as Alzheimer's and Parkinson's disease.

The spontaneously hypertensive rat and the stroke-prone spontaneously hypertensive rat are useful models for human hypertension. In these strains hypertension is a polygenic trait, in which both autosomal and sex-linked genes can influence blood pressure. Linkage studies in crosses between the stroke-prone spontaneously hypertensive rat and the normotensive control strain Wistar-Kyoto have led to the localization of two genes, BP/SP-1 and BP/SP-2, that contribute significantly to blood pressure variation in the F2 population. BP/SP-1 and BP/SP-2 were assigned to rat chromosomes 10 and X, respectively. Comparison of the human and rat genetic maps indicates that BP/SP-1 could reside on human chromosome 17q in a region that also contains the angiotensin I-converting enzyme gene (ACE). This encodes a key enzyme of the renin-angiotensin system, and is therefore a candidate gene in primary hypertension. A rat microsatellite marker of ACE was mapped to rat chromosome 10 within the region containing BP/SP-1.

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