Multiple anaphase-promoting complex/cyclosome degrons mediate the degradation of human Sgo1.
Multiple anaphase-promoting complex/cyclosome degrons mediate the degradation of human Sgo1.
复制标题
DOI：
10.1074/jbc.m807083200
复制
发表时间：
2009-01-16
影响因子：
4.8
通讯作者：
Yu, Hongtao
中科院分区：
文献类型：
--
作者：
Karamysheva, Zemfira;Diaz-Martinez, Laura A.;Crow, Sara E.;Li, Bing;Yu, Hongtao
Shugoshin 1 (Sgo1) 在早期有丝分裂中保护着丝粒姐妹染色单体的凝聚力，从而防止姐妹染色单体过早分离。 Sgo1 的蛋白水平在细胞周期中受到调节；它在有丝分裂中达到峰值，并在 G1/S 中下调。在这里，我们发现 Sgo1 在有丝分裂退出过程中被降解，其降解取决于后期促进复合物/环体（APC/C）。 Cdh1 的过度表达会降低人类细胞中异位表达的 Sgo1 的蛋白水平。在体外，Sgo1 被与 Cdh1 (APC/CCdh1) 结合的 APC/C 泛素化。我们进一步鉴定了 Sgo1 中的两个功能降解基序；即KEN（Lys-Glu-Asn）盒和破坏盒（D盒）。尽管去除任一基序都不足以稳定 Sgo1，但同时删除 KEN 盒和 D 盒的 Sgo1 在细胞中是稳定的。令人惊讶的是，有丝分裂在不可降解的 Sgo1 存在的情况下正常进行，表明姐妹染色单体分离或有丝分裂退出不需要 Sgo1 的降解。最后，我们证明纺锤体检查点激酶 Bub1 有助于以 APC/C 独立机制维持 Sgo1 稳态蛋白水平。
Shugoshin 1 (Sgo1) protects centromeric sister-chromatid cohesion in early mitosis and, thus, prevents premature sister-chromatid separation. The protein level of Sgo1 is regulated during the cell cycle; it peaks in mitosis and is down-regulated in G1/S. Here we show that Sgo1 is degraded during the exit from mitosis, and its degradation depends on the anaphase-promoting complex/cyclosome (APC/C). Overexpression of Cdh1 reduces the protein levels of ectopically expressed Sgo1 in human cells. Sgo1 is ubiquitinated by APC/C bound to Cdh1 (APC/CCdh1) in vitro. We have further identified two functional degradation motifs in Sgo1; that is, a KEN (Lys-Glu-Asn) box and a destruction box (D box). Although removal of either motif is not sufficient to stabilize Sgo1, Sgo1 with both KEN box and D box deleted is stable in cells. Surprisingly, mitosis progresses normally in the presence of non-degradable Sgo1, indicating that degradation of Sgo1 is not required for sister-chromatid separation or mitotic exit. Finally, we show that the spindle checkpoint kinase Bub1 contributes to the maintenance of Sgo1 steady-state protein levels in an APC/C-independent mechanism.