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Autophagy mediates SUMO-induced degradation of a polyglutamine protein ataxin-3

Animal Cells and Systems 2017년 21권 3호 p.169 ~ 176
황수평, 이도희,
소속 상세정보
황수평 ( Hwang Soo-Pyung ) - Seoul Women’s University College of Natural Science Department of Bio and Environmental Technology
이도희 ( Lee Do-Hee ) - Seoul Women’s University College of Natural Science Department of Bio and Environmental Technology

Abstract


Previously, we reported that small ubiquitin-like modifier-1 (SUMO-1) promotes the degradation of a polyglutamine (polyQ) protein ataxin-3 and proposed that proteasomes mediate the proteolysis. Here, we present evidence that autophagy is also responsible for SUMO-induced degradation of this polyQ protein. The autophagy inhibitor 3-MA increased the steady-state level of ataxin-3 and stabilized SUMO-modified ataxin-3 more prominently than the proteasome inhibitor MG132. Interestingly, SUMO-1 overexpression enhanced the co-localization of ataxin-3 and autophagy marker LC3 without increasing LC3 puncta formation suggesting that SUMO-1 is involved in the substrate recruitment rather than the induction of autophagy. To assess the importance of a putative SUMO-interacting motif (SIM) in ataxin-3 for SUMO-induced degradation, we constructed a SIM mutant of ataxin-3. Substitution of putative SIM (V165G) facilitated the degradation of polyQ-expanded ataxin-3, which is more resistant to SUMO-induced degradation than the normal ataxin-3. These results together indicate that SUMO-1 promotes the degradation of ataxin-3 via autophagy and the putative SIM of ataxin-3 plays a role in this process.

키워드

Ataxin-3; SUMO; autophagy; SUMO-interacting motif

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