Geminin Cleavage during Apoptosis by Caspase-3 Alters Its Binding Ability to the SWI/SNF Subunit Brahma*
Geminin Cleavage during Apoptosis by Caspase-3 Alters Its Binding Ability to the SWI/SNF Subunit Brahma*
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DOI：
10.1074/jbc.m611643200
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发表时间：
2007-03
影响因子：
4.8
通讯作者：
Vassilis Roukos;M. Iliou;H. Nishitani;M. Gentzel;M. Wilm;S. Taraviras;Z. Lygerou
中科院分区：
文献类型：
--
作者：
Vassilis Roukos;M. Iliou;H. Nishitani;M. Gentzel;M. Wilm;S. Taraviras;Z. Lygerou
双黄素被认为通过与细胞周期调节因子CDT1以及与细胞命运决定有关的同源盒转录因子和染色质重塑活动的平衡相互作用来协调细胞周期和分化事件。在这里，我们展示了在原代细胞和癌细胞系中，双黄素被裂解，并在各种刺激下诱导细胞发生凋亡。Caspase-3在体内和体外均可介导Ginin靶向。Caspase裂解双生蛋白羧基末端的两个位点(命名为C1和C2)，产生截短形式的双生蛋白。我们提供的证据表明，双生蛋白的切割是由磷酸化调节的。酪蛋白激酶II在体外改变了C1点的Ginin切割，而C1点附近的突变的磷酸化活性Ser/Thr残基影响体内的Ginin切割。我们的研究表明，由C1区切割产生的截短双黄素可以促进细胞凋亡。相反，切割在C2位的Ginin已经失去了与SWI/SNF染色质重塑复合体的催化亚单位Brahma(BRM)相互作用的能力，而有效地与CDT1结合，表明在细胞凋亡过程中靶向Ginin对与其结合伙伴的相互作用产生了不同的影响。
Geminin has been proposed to coordinate cell cycle and differentiation events through balanced interactions with the cell cycle regulator Cdt1 and with homeobox transcription factors and chromatin remodeling activities implicated in cell fate decisions. Here we show that Geminin is cleaved in primary cells and cancer cell lines induced to undergo apoptosis by a variety of stimuli. Geminin targeting is mediated by caspase-3 both in vivo and in vitro. Two sites at the carboxyl terminus of Geminin (named C1 and C2) are cleaved by the caspase, producing truncated forms of Geminin. We provide evidence that Geminin cleavage is regulated by phosphorylation. Casein kinase II alters Geminin cleavage at site C1 in vitro, whereas mutating phosphorylation competent Ser/Thr residues proximal to site C1 affects Geminin cleavage in vivo. We show that truncated Geminin produced by cleavage at C1 can promote apoptosis. In contrast, Geminin cleaved at site C2 has lost the ability to interact with Brahma (Brm), a catalytic subunit of the SWI/SNF chromatin remodeling complex, while binding efficiently to Cdt1, indicating that targeting of Geminin during apoptosis differentially affects interactions with its binding partners.