Molecular clearance of ataxin-3 is regulated by a mammalian E4.
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| Abstract |
Insoluble aggregates of polyglutamine-containing proteins are usually conjugated with ubiquitin in neurons of individuals with polyglutamine diseases. We now show that ataxin-3, in which the abnormal expansion of a polyglutamine tract is responsible for spinocerebellar ataxia type 3 (SCA3), undergoes ubiquitylation and degradation by the proteasome. Mammalian E4B (UFD2a), a ubiquitin chain assembly factor (E4), copurified with the polyubiquitylation activity for ataxin-3. E4B interacted with, and thereby mediated polyubiquitylation of, ataxin-3. Expression of E4B promoted degradation of a pathological form of ataxin-3. In contrast, a dominant-negative mutant of E4B inhibited degradation of this form of ataxin-3, resulting in the formation of intracellular aggregates. In a Drosophila model of SCA3, expression of E4B suppressed the neurodegeneration induced by an ataxin-3 mutant. These observations suggest that E4 is a rate-limiting factor in the degradation of pathological forms of ataxin-3, and that targeted expression of E4B is a potential gene therapy for SCA3.
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| Authors | Masaki Matsumoto, Masayoshi Yada, Shigetsugu Hatakeyama, Hiroshi Ishimoto, Teiichi Tanimura, Shoji Tsuji, Akira Kakizuka, Masatoshi Kitagawa, Keiichi I Nakayama |
| Journal | The EMBO journal (EMBO J) Vol. 23 Issue 3 Pg. 659-69 (Feb 11 2004) ISSN: 0261-4189 [Print] England |
| PMID | 14749733 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't) |
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