The ubiquitin-conjugating enzyme UbcH6 regulates the transcriptional repression activity of the SCA1 gene product ataxin-1.
Spinocerebellar ataxia type 1 (SCA1) is an autosomal-dominant neurodegenerative disorder characterized by ataxia and progressive motor deterioration. SCA1 is caused by expansion of the polyglutamine tract in the SCA1 gene product, ataxin-1. We previously reported that the E2 ubiquitin-conjugating enzyme UbcH6 interacts with and ubiquitinates the ataxin-1 proteins as an E2-substrate cognate pair in the ubiquitin-proteasome system. In the present study, we further investigated whether the function of ataxin-1 is associated with UbcH6 and found that UbcH6 regulates the transcriptional repression activity of ataxin-1. The overexpression of UbcH6 reduced the transcriptional repression activity of ataxin-1. Interestingly, ataxin-1(30Q) was more affected by the presence of UbcH6 than ataxin-1(82Q), implying that the length of the polyglutamine tract in ataxin-1 might be involved in determining the stability of ataxin-1. The half-life of ataxin-1(82Q) was longer than that of ataxin-1(30Q) in the presence of UbcH6. shRNAs targeting UbcH6 enhanced the transcriptional repression activity of ataxin-1. In addition, the overexpression of UbcH6 reduced the formation of ataxin-1 aggregates. Our studies demonstrate that UbcH6 modulates the transcriptional repression activity of ataxin-1 by modulating the degradation of ataxin-1, suggesting that UbcH6 may have some therapeutic potential in the treatment of SCA1.
Lee
Soyeon
S
Graduate School of Life Sciences and Biotechnology, Korea University, 1, 5ka, Anam-dong, Sungbuk-Ku, Seoul 136-701, Republic of Korea.
Hong
Sunghoi
S
Kang
Seongman
S
D000067696:Ataxin-1; D000067528:Ataxins; D002460:Cell Line; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D008156:Luciferases / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020754:Spinocerebellar Ataxias / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism*
C000593749:ATXN1 protein, human; D000067696:Ataxin-1; D000067528:Ataxins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D008156:Luciferases; C489963:UBE2E1 protein, human; D044763:Ubiquitin-Conjugating Enzymes