Analysis of the cell cycle regulation of chromosome condensation protein complex, condensin.

染色体凝缩蛋白复合物凝缩蛋白的细胞周期调控分析。

• 批准号: 15370091
• 负责人: KIMURA Keiji
• 金额: $ 9.66万
• 依托单位: RIKEN
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15370091/
• 关键词: condensin; SMC; phosphorylation; chromatin; chromosome condensation; cell cycle; Cdc2; CK2; クロマチン構造; SMCタンパク質; Cdc2キナーゼ; カゼインキナーゼII; HeLa細胞; 細胞分裂期; 染色体分配; condensin; SMC; phosphorylation; chromatin; chromosome condensation; cell cycle; Cdc2; CK2; クロマチン構造; SMCタンパク質; Cdc2キナーゼ; カゼインキナーゼII; HeLa細胞; 細胞分裂期; 染色体分配

Condensin, a conserved pentameric protein complex composed of SMC heterodimer (SMC2/CAP-E and SMC4/CAP-E) and three other non-SMC subunits (CAP-D2, -G, and -H), plays an essential role in mitotic chromosome condensation in vivo. Condensin induces positive supercoiling into DNA in the presence of topo I using the energy of ATP hydrolysis in vitro. In addition to their mitotic functions, condensins have been implicated in chromatin regulation during interphase, such as DNA repair, damage checkpoint response and transcriptional regulation.We analyzed precisely cell cycle regulation of condensin complex. The protein levels and stabilities of condensin subunits were almost constant throughout the cell cycle. Condensin was phosphorylated by Cdc2 during mitosis, and by CK2 during interphase. In contrast to the stimulatory effect of Cdc2-induced phosphorylation of condensin I on supercoiling, phosphorylation by CK2 reduced the supercoiling activity of condensin I. CK2-mediated phosphorylation of condensin I is spatially and temporally regulated in a manner different to that of Cdc2-mediated phosphorylation : CK2-dependent phosphorylation increases during interphase and decreases on chromosomes during mitosis. These findings are the first to demonstrate a negative regulatory mode for condensin I, a process that may influence chromatin structure during interphase and mitosis.When condensin was added into in vitro transcription system, transcription level was reduced, and the suppression was cancelled by the CK2-mediated phosphorylation. Thus, it is possible chromatin structure was compacted by condensin during interphase, and inhibition of condensin activity by the CK2-mediated phosphorylation leads to relaxation of chromatin structure and transactivation.

Condens是由SMC异二聚体（SMC2/CAP-E和SMC4/CAP-E）组成的保守的五聚蛋白复合物和其他三个非SMC亚基（CAP-D2，-G和-H），在Vivo In Vivo中起着有丝分裂性染色体凝结的重要作用。在Topo I的存在下，使用ATP水解体外的能量，凝聚蛋白诱导阳性超螺旋进入DNA。除了它们的有丝分裂功能外，冷凝蛋白还与相间期间的染色质调节有关，例如DNA修复，损伤检查点响应和转录调节。我们精确地分析了冷凝蛋白复合物的细胞周期调节。在整个细胞周期中，冷凝蛋白亚基的蛋白质水平和稳定性几乎是恒定的。在有丝分裂过程中，通过CDC2和CK2在相间期间通过CDC2磷酸化。与CDC2诱导的冷凝蛋白I磷酸化对超串联磷酸化的刺激作用相反，CK2通过CK2降低了冷凝蛋白I. CK2介导的冷凝蛋白I的超串联活性，在空间和时间上以与CDC2介导的磷酸化相互作用的方式在空间和时间上受到不同的调节：有丝分裂过程中的染色体。这些发现是第一个证明冷凝蛋白I的负调控模式的发现，该过程可能会在相间和有丝分裂过程中影响染色质结构。当将冷凝蛋白添加到体外转录系统中时，转录水平降低，并被CK2介导的磷酸化取消。因此，可能在相间期间通过冷凝蛋白压实染色质结构，并通过CK2介导的磷酸化对冷凝素活性抑制会导致染色质结构和反式激活的松弛。