Adachi Yoh, Kokubu Aya, Ebe Masahiro, Nagao Koji, Yanagida Mitsuhiro
CREST Research Program, Japan Science and Technology Corporation, Graduate School of Biostudies, Kyoto University, Yoshida-Honmachi, Kyoto, Japan.
Cell Cycle. 2008 Mar 15;7(6):765-76. doi: 10.4161/cc.7.6.5530. Epub 2007 Dec 29.
Cohesin is a multiprotein complex essential for sister-chromatid cohesion. It plays a pivotal role in proper chromosome segregation and DNA damage repair. The mitotic behavior of cohesin is controlled through its phosphorylation, which possibly induces the dissociation of cohesin from chromosomes and enhances its susceptibility to separase. Here, we report using mass spectrometry and anti-phospho antibodies that the central domain of Rad21, the separase-target subunit of Schizosaccharomyces pombe cohesin, is regulated by various kinase-induced phosphorylation at nine residues, indicating the multiple roles for S. pombe cohesin. In vegetative and non-dividing G(0) cells, Rad21 is phosphorylated by unknown S/TP-consensus kinases, in mitotic and non-mitotic cells by polo/Plo1 and CDK, and in DNA-damaged cells by Rad3/ATR. While mitotic phosphorylation is implicated in the dissociation of Rad21 and its cleavage by separase in anaphase, the Rad3/ATR-dependent damage-induced phosphorylation occurs intensively at the time of repair completion, and only in post-replicative cells. This damage-induced Rad21 phosphorylation is involved in the recovery process of cells from checkpoint arrest, and needed for the removal of cohesin by separase after the completion of damage repair. These complex phospho-regulations of Rad21 indicate the functional significance of cohesin in cell adaptation to a variety of cellular conditions.
黏连蛋白是一种对姐妹染色单体黏连至关重要的多蛋白复合体。它在正确的染色体分离和DNA损伤修复中起着关键作用。黏连蛋白的有丝分裂行为通过其磷酸化来控制，这可能诱导黏连蛋白从染色体上解离，并增强其对分离酶的敏感性。在此，我们使用质谱分析和抗磷酸化抗体报告称，粟酒裂殖酵母黏连蛋白的分离酶作用靶点亚基Rad21的中央结构域受到9个残基上多种激酶诱导的磷酸化调节，这表明粟酒裂殖酵母黏连蛋白具有多种作用。在营养生长和非分裂的G(0)期细胞中，Rad21被未知的S/TP保守序列激酶磷酸化；在有丝分裂和非有丝分裂细胞中被polo/Plo1和CDK磷酸化；在DNA损伤细胞中被Rad3/ATR磷酸化。虽然有丝分裂磷酸化与Rad21在后期的解离及其被分离酶切割有关，但Rad3/ATR依赖的损伤诱导磷酸化在修复完成时强烈发生且仅在复制后细胞中出现。这种损伤诱导的Rad21磷酸化参与细胞从检查点阻滞中恢复的过程，并且在损伤修复完成后是分离酶去除黏连蛋白所必需的。Rad21这些复杂的磷酸化调控表明黏连蛋白在细胞适应各种细胞条件中的功能意义。
