Caspase-mediated activation and induction of apoptosis by the mammalian Ste20-like kinase Mst1
Caspase-mediated activation and induction of apoptosis by the mammalian Ste20-like kinase Mst1
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DOI：
10.1093/emboj/17.8.2224
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发表时间：
1998-04-15
期刊：
影响因子：
11.4
通讯作者：
Krebs, EG
中科院分区：
文献类型：
--
作者：
Graves, JD;Gotoh, Y;Krebs, EG
Mst 1是一种广泛表达的丝氨酸-苏氨酸激酶，与芽殖酵母Ste 20同源，其生理调节和细胞功能尚不清楚。在本文中，我们表明，在交联CD 95/Fas或星形孢菌素处理诱导的细胞凋亡过程中，Mst 1被半胱天冬酶3样活性特异性切割，CD 95/Fas诱导的Mst 1裂解被半胱氨酸蛋白酶抑制剂ZVAD-fetus、更具选择性的半胱天冬酶抑制剂DEVD-CBB和病毒丝氨酸蛋白酶抑制剂CrmA阻断，半胱天冬酶介导的Mst 1切割去除了C-末端调节结构域，并与体内Mst 1活性的增加相关，与半胱天冬酶介导的切割激活Mst 1一致。野生型Mst 1或截短突变体的过表达诱导细胞凋亡的形态学变化特征，此外，外源表达的Mst 1被切割，表明Mst 1可以激活导致其切割的半胱天冬酶。激酶死亡的Mst 1不诱导形态学改变，并且在过表达时不被切割，这表明Mst 1必须具有催化活性以介导这些作用。在共转染测定中，Mst 1激活MKK 6、p38 MAPK、MKK 7和SAPK，这表明Mst 1可能激活这些途径。我们的研究结果表明，存在一个正反馈回路，涉及Mst 1，并可能SAPK和p38 MAPK途径，这有助于放大凋亡反应。
Mst1 is a ubiquitously expressed serine-threonine kinase, homologous to the budding yeast Ste20, whose physiological regulation and cellular function are unknown, In this paper we show-that Mst1 is specifically cleaved by a caspase 3-like activity during apoptosis induced by either cross-linking CD95/Fas or by staurosporine treatment, CD95/Fas-induced cleavage of Mst1 was blocked by the cysteine protease inhibitor ZVAD-fmk the more selective caspase inhibitor DEVD-CBB and by the viral serpin CrmA, caspase-mediated cleavage of Mst1 removes the C-terminal regulatory domain and correlates with an increase in Mst1 activity in vivo, consistent with caspase-mediated cleavage activating Mst1. Overexpression of either wild-type Mst1 or a truncated mutant induces morphological changes characteristic of apoptosis, Furthermore, exogenously expressed Mst1 is cleaved, indicating that Mst1 can activate caspases that result in its cleavage. Kinase-dead Mst1 did not induce morphological alterations and was not cleaved upon overexpression, indicating that Mst1 must be catalytically active in order tee mediate these effects, Mst1 activates MKK6, p38 MAPK, MKK7 and SAPK in co-transfection assays, suggesting that Mst1 may activate these pathways. Our findings suggest the existence of a positive feedback loop involving Mst1, and possibly the SAPK and p38 MAPK pathways, which serves to amplify the apoptotic response.