Enhanced JNK activation by NESK without kinase activity upon caspase-mediated cleavage during apoptosis
Enhanced JNK activation by NESK without kinase activity upon caspase-mediated cleavage during apoptosis
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DOI：
10.1016/j.cellsig.2005.03.004
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发表时间：
2005-11-01
影响因子：
4.8
通讯作者：
Kitamura, N
中科院分区：
文献类型：
--
作者：
Kakinuma, H;Inomata, H;Kitamura, N
Nck 相互作用激酶样胚胎特异性激酶 (NESK) 是一种蛋白激酶，主要在小鼠胚胎发生后期的骨骼肌中表达。 NESK 属于生发中心激酶 (GCK) 家族，当在培养细胞中过度表达时，会选择性激活 c-Jun N 末端激酶 (INK) 通路。 GCK 家族的一些成员已被证明在细胞凋亡过程中被蛋白水解裂解和激活。在这里，我们报告 NESK 在细胞凋亡过程中也会被蛋白水解裂解。在放线菌酮存在下，用 TNF-α 处理 NESK 转染的 HeLa 细胞，或用星形孢菌素诱导 NESK 蛋白水解。 NESK 的裂解发生在两个位点，产生三个片段：包含激酶结构域的 N 端片段、中间片段和包含调节性 CNH 结构域的 C 端片段。这两个裂解以逐步方式发生并且依赖于半胱天冬酶活性。切割位点被鉴定为 868 和 1091 处的天冬氨酸残基。N 末端片段的激酶活性低于全长 NESK，并且不激活 INK 途径。相比之下，C 端片段比全长 NESK 更强烈地激活 INK 通路，并促进 TNF-α 诱导的细胞凋亡。这些结果表明 NESK 通过细胞凋亡过程中蛋白水解裂解产生的 C 末端调节域，以不同于其他 GCK 家族激酶的独特方式参与 INK 途径介导的细胞凋亡促进。 (c) 2005 Elsevier Inc. 保留所有权利。
Nck-interacting kinase-like embryo-specific kinase (NESK) is a protein kinase that is predominantly expressed in skeletal muscle during the late stages of mouse embryogenesis. NESK belongs to the germinal center kinase (GCK) family and selectively activates the c-Jun N-terminal kinase (INK) pathway when overexpressed in cultured cells. Some members of the GCK family have been shown to be proteolytically cleaved and activated during apoptosis. Here, we report that NESK is also proteolytically cleaved during apoptosis. Treatment of NESK-transfected HeLa cells with TNF-alpha in the presence of cycloheximide or with staurosporine induced proteolytic cleavage of NESK. The cleavage of NESK occurred at two sites, generating three fragments: an N-terminal fragment containing a kinase domain, an intermediate fragment and a C-terminal fragment containing a regulatory CNH domain. These two cleavages occurred in a stepwise manner and were dependent on a caspase activity. The cleavage sites were identified as aspartic acid residues at 868 and 1091. The N-terminal fragment had less kinase activity than the full-length NESK and did not activate the INK pathway. In contrast, the C-terminal fragment activated the INK pathway more strongly than the full-length NESK and promoted TNF-alpha-induced apoptotic cell death. These results implicate NESK in the INK pathway-mediated promotion of apoptosis through its C-terminal regulatory domain generated by proteolytic cleavage during apoptosis, in a unique manner different from other GCK family kinases. (c) 2005 Elsevier Inc. All rights reserved.