Li H, Bergeron L, Cryns V, Pasternack M S, Zhu H, Shi L, Greenberg A, Yuan J
Cardiovascular Research Center, Massachusetts General Hospital-East, Charlestown, Massachusetts 02129 and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA.
J Biol Chem. 1997 Aug 22;272(34):21010-7. doi: 10.1074/jbc.272.34.21010.
Members of the CED-3/interleukin-1beta-converting enzyme (ICE) protease (caspase) family are synthesized as proforms, which are proteolytically cleaved and activated during apoptosis. We report here that caspase-2 (ICH-1/NEDD-2), a member of the ICE family, is activated during apoptosis by another ICE member, a caspase-3 (CPP32)-like protease(s). When cells are induced to undergo apoptosis, endogenous caspase-2 is first cleaved into three fragments of 32-33 kDa and 14 kDa, which are then further processed into 18- and 12-kDa active subunits. Up to 50 microM N-acetyl-Asp-Glu-Val-Asp-aldehyde (DEVD-CHO), a caspase-3-preferred peptide inhibitor, inhibits caspase-2 activation and DNA fragmentation in vivo, but does not prevent loss of mitochondrial function, while higher concentrations of DEVD-CHO (>50 microM) inhibit both. In comparison, although the activity of caspase-3 is very sensitive to the inhibition of DEVD-CHO (<50 nM), inhibition of caspase-3 activation as marked by processing of the proform requires more than 100 microM DEVD-CHO. Our results suggest that the first cleavage of caspase-2 is accomplished by a caspase-3-like activity, and other ICE-like proteases less sensitive to DEVD-CHO may be responsible for activation of caspase-3 and loss of mitochondrial function.
CED-3/白细胞介素-1β转化酶（ICE）蛋白酶（半胱天冬酶）家族成员以无活性前体形式合成，在细胞凋亡过程中经蛋白水解切割而被激活。我们在此报告，ICE家族成员半胱天冬酶-2（ICH-1/NEDD-2）在细胞凋亡过程中被另一个ICE成员、一种类似半胱天冬酶-3（CPP32）的蛋白酶激活。当细胞被诱导发生凋亡时，内源性半胱天冬酶-2首先被切割成32 - 33 kDa和14 kDa的三个片段，然后进一步加工成18 kDa和12 kDa的活性亚基。高达50 μM的N-乙酰-天冬氨酸-谷氨酸-缬氨酸-天冬氨酸醛（DEVD-CHO），一种半胱天冬酶-3偏好的肽抑制剂，在体内抑制半胱天冬酶-2的激活和DNA片段化，但不阻止线粒体功能的丧失，而更高浓度的DEVD-CHO（>50 μM）则两者都抑制。相比之下，尽管半胱天冬酶-3的活性对DEVD-CHO（<50 nM）的抑制非常敏感，但以前体加工为标志的半胱天冬酶-3激活的抑制需要超过100 μM的DEVD-CHO。我们的结果表明，半胱天冬酶-2的首次切割是由一种类似半胱天冬酶-3的活性完成的，而其他对DEVD-CHO不太敏感的ICE样蛋白酶可能负责半胱天冬酶-3的激活和线粒体功能的丧失。
