cIAP1 Cooperatively Inhibits Procaspase-3 Activation by the Caspase-9 Apoptosome
cIAP1 Cooperatively Inhibits Procaspase-3 Activation by the Caspase-9 Apoptosome
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DOI：
10.1074/jbc.m110.125955
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发表时间：
2010-09-24
影响因子：
4.8
通讯作者：
Smith, Jeffrey B.
中科院分区：
文献类型：
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作者：
Burke, Stephen P.;Smith, Lucinda;Smith, Jeffrey B.
虽然早期的凋亡抑制蛋白（IAP）研究表明，cIAP 1直接结合和抑制半胱天冬酶类似于X-连锁IAP（XIAP），最近的一项研究发现，微摩尔浓度的cIAP 1只能微弱抑制半胱天冬酶-3，-7，或-9。在这里，我们表明，cIAP 1特异性和合作块细胞色素c依赖性的溶酶体在体外。因此，cIAP 1阻止了半胱天冬酶原-3的活化，但对半胱天冬酶原-9的加工或先前活化的半胱天冬酶-3的活性没有影响。与cIAP 1一样，XIAP对半胱氨酸天冬氨酸蛋白酶原-9的加工没有影响，并且是比已经激活的半胱氨酸天冬氨酸蛋白酶原-3活性更有效的半胱氨酸天冬氨酸蛋白酶原-3激活抑制剂。对procaspase-3激活的抑制依赖于cIAP 1的BIR 2和BIR 3，而不依赖于BIR 1、RING、CARD和乌巴结构域。Smac阻止cIAP 1抑制半胱氨酸天冬氨酸蛋白酶原-3活化，并通过预先加入cIAP 1逆转抑制。不能产生p12亚基的蛋白酶原-9突变体（D315 A）对cIAP 1的抑制具有抗性。因此，caspase-9转录体的p12亚基的N-末端Ala-Thr-Pro-Phe基序促进转录体阻断。因此，cIAP 1协同作用与寡聚化加工的caspase-9在溶酶体和阻断caspase-3的活化。
Although early studies of inhibitor of apoptosis proteins (IAPs) suggested that cIAP1 directly binds and inhibits caspases similarly to X-linked IAP (XIAP), a recent one found that micromolar concentrations of cIAP1 only weakly inhibit caspase-3, -7, or -9. Here, we show that cIAP1 specifically and cooperatively blocks the cytochrome c-dependent apoptosome in vitro. Hence, cIAP1 prevented the activation of procaspase-3 but had no effect on the processing of procaspase-9 or the activity of prior activated caspase-3. Like cIAP1, XIAP had no effect on procaspase-9 processing and was a more potent inhibitor of procaspase- 3 activation than of already activated caspase-3 activity. Inhibition of procaspase-3 activation depended on BIR2 and BIR3 of cIAP1 and was independent of BIR1, RING, CARD, and UBA domains. Smac prevented cIAP1 from inhibiting procaspase- 3 activation and reversed the inhibition by prior addition of cIAP1. A procaspase-9 mutant (D315A) that cannot produce the p12 subunit was resistant to inhibition by cIAP1. Therefore, the N-terminal Ala-Thr-Pro-Phe motif of the p12 subunit of the caspase-9 apoptosome facilitates apoptosome blockade. Consequently, cIAP1 cooperatively interacts with oligomerized processed caspase-9 in the apoptosome and blocks procaspase-3 activation.