- Erratum in:
- Neuron 2001 Dec 6;32(5):957-8.
- Comment in:
-
Neuron. 2001 Sep 27;31(6):875-6.
Polyglutamine-expanded ataxin-7 antagonizes CRX function and induces cone-rod dystrophy in a mouse model of SCA7.
La Spada AR,
Fu YH,
Sopher BL,
Libby RT,
Wang X,
Li LY,
Einum DD,
Huang J,
Possin DE,
Smith AC,
Martinez RA,
Koszdin KL,
Treuting PM,
Ware CB,
Hurley JB,
Ptácek LJ,
Chen S.
Department of Laboratory Medicine, University of Washington Medical Center, Seattle, WA 98195, USA. laspada@u.washington.edu
Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant disorder caused by a CAG repeat expansion. To determine the mechanism of neurotoxicity, we produced transgenic mice and observed a cone-rod dystrophy. Nuclear inclusions were present, suggesting that the disease pathway involves the nucleus. When yeast two-hybrid assays indicated that cone-rod homeobox protein (CRX) interacts with ataxin-7, we performed further studies to assess this interaction. We found that ataxin-7 and CRX colocalize and coimmunoprecipitate. We observed that polyglutamine-expanded ataxin-7 can dramatically suppress CRX transactivation. In SCA7 transgenic mice, electrophoretic mobility shift assays indicated reduced CRX binding activity, while RT-PCR analysis detected reductions in CRX-regulated genes. Our results suggest that CRX transcription interference accounts for the retinal degeneration in SCA7 and thus may provide an explanation for how cell-type specificity is achieved in this polyglutamine repeat disease.
PMID: 11580893 [PubMed - indexed for MEDLINE]