Mimicking Cdk2 phosphorylation of Bcl-xL at Ser73 results in caspase activation and Bcl-xL cleavage.
Mimicking Cdk2 phosphorylation of Bcl-xL at Ser73 results in caspase activation and Bcl-xL cleavage.
复制标题
模拟 Bcl-xL Ser73 位点的 Cdk2 磷酸化会导致 caspase 激活和 Bcl-xL 裂解。
DOI：
10.1038/cddiscovery.2016.1
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发表时间：
2016
影响因子：
7
通讯作者：
Price,PM
中科院分区：
文献类型：
--
作者：
Seng,NS;Megyesi,J;Tarcsafalvi,A;Price,PM
顺铂是一种广泛使用的化疗药物，但其疗效受到肾毒性的限制。肾毒性的严重程度与肾细胞死亡的程度相关。以前，我们发现顺铂诱导的肾细胞死亡依赖于Cdk 2的激活，并且Cdk 2的抑制保护细胞免受顺铂诱导的凋亡。使用体外激动试验，我们表明Cdk 2在第73位丝氨酸磷酸化Bcl-xL（Bcl-2家族蛋白的抗凋亡成员）。我们还发现，这种磷酸化的Bcl-xL参与细胞死亡，因为Bcl-xL在丝氨酸73位点的磷酸化模拟突变体（S73 D-Bcl-xL）激活半胱天冬酶。我们现在发现S73 D-Bcl-xL在D 61和D 76处被切割，这是推定的半胱天冬酶切割位点，以产生15-kDa和12-kDa片段。与全长Bcl-xL不同，Bcl-xL的这些切割产物先前被报道为促凋亡的。我们试图确定这些Bcl-xL片段是否是S73 D-Bcl-xL诱导细胞死亡所必需的。这些半胱天冬酶切割位点的突变阻止了15-kDa和12-kDa Bcl-xL切割产物的形成，但凋亡仍然持续在S73 D修饰的Bcl-xL中。我们的研究结果表明，Bcl-xL在Ser 73处的Cdk 2磷酸化（而不是Bcl-xL切割产物）对于诱导细胞死亡是必要且足够的。
Cisplatin is a widely used chemotherapeutic agent, yet its efficacy is limited by nephrotoxicity. The severity of nephrotoxicity is associated with the extent of kidney cell death. Previously, we found that cisplatin-induced kidney cell death was dependent on Cdk2 activation, and inhibition of Cdk2 protected cells from cisplatin-induced apoptosis. Using an in vitro kination assay, we showed that Cdk2 phosphorylated Bcl-xL, an anti-apoptotic member of Bcl-2 family proteins, at serine 73. We also found that this phosphorylated Bcl-xL participated in cell death, as a phosphomimetic mutant of Bcl-xL at the serine 73 site (S73D-Bcl-xL) activated caspases. We now find that S73D-Bcl-xL was cleaved at D61 and D76, which are putative caspase cleavage sites, to generate 15-kDa and 12-kDa fragments. Unlike full-length Bcl-xL, these cleavage products of Bcl-xL were previously reported to be pro-apoptotic. We sought to determine whether these Bcl-xL fragments were necessary for the induction of cell death by S73D-Bcl-xL. Mutation of these caspase cleavage sites prevented the formation of the 15-kDa and 12-kDa Bcl-xL cleavage products, but apoptosis still persisted in a S73D modified Bcl-xL. Our findings show that Cdk2 phosphorylation of Bcl-xL at Ser73, but not the Bcl-xL cleavage products, is necessary and sufficient to induce cell death.