Novel Death Defying Domain in Met entraps the active site of caspase-3 and blocks apoptosis in hepatocytes.
Novel Death Defying Domain in Met entraps the active site of caspase-3 and blocks apoptosis in hepatocytes.
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DOI：
10.1002/hep.26769
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发表时间：
2014-05
期刊：
影响因子：
13.5
通讯作者：
Zarnegar, Reza
中科院分区：
文献类型：
--
作者：
Ma, Jihong;Zou, Chunbin;Guo, Lida;Seneviratne, Danushka S.;Tan, Xinping;Kwon, Yong-Kook;An, Jiyan;Bowser, Robert;DeFrances, Marie C.;Zarnegar, Reza
Met是肝细胞生长因子（HGF）的跨膜酪氨酸激酶受体，已知在正常细胞和肿瘤细胞中作为一种有效的抗凋亡介质发挥作用。在本文中，我们报告细胞内的细胞质尾的Met已演变为窝藏一对串联的Caspase-3切割位点，其诱饵，陷阱和禁用Caspase-3的活性位点，从而阻止细胞凋亡的执行。我们将这种Caspase-3切割基序称为“死亡挑战结构域”（DDD）。该位点由以下序列组成：DNAD-DEVD-T（其中连字符表示半胱天冬酶切割位点）。通过功能和机制研究，我们表明，DDD裂解的Caspase-3，所得的DEVD-T肽作为一个竞争性抑制剂，并截留的Caspase-3的活性位点类似于DEVD-CHO，这是一个有效的，合成的Caspase-3活性抑制剂。通过使用DDD缺陷肝细胞中DDD表达恢复的功能获得和丧失研究，我们发现DDD中的两个Caspase-3位点对于抑制Caspase-3和促进细胞存活是必需的。采用诱变研究，我们表明，DDD可以独立于Met的酶活性，通过使用激酶死亡的人Met突变体构建体确定。对人肝癌组织和细胞系的研究发现，DDD切割和DDD对Caspase-3的截留在体内发生，进一步证明该位点具有生理和病理生理相关性。我们的研究结果表明，Met可以通过一种新的机制直接抑制Caspase-3，并促进肝细胞的存活。这里提出的结果将进一步我们了解的机制，不仅控制正常组织的稳态，但也异常的组织生长，如癌症和退行性疾病，其中凋亡半胱天冬酶在发挥作用。
Met, the transmembrane tyrosine kinase receptor for hepatocyte growth factor (HGF) is known to function as a potent anti-apoptotic mediator in normal and neoplastic cells. Herein we report that intracellular cytoplasmic tail of Met has evolved to harbor a tandem pair of Caspase-3 cleavage sites, which bait, trap and disable the active site of Caspase-3, thereby blocking the execution of apoptosis. We call this Caspase-3 cleavage motif the ‘Death Defying Domain’ (DDD). This site consists of the following sequence: DNAD-DEVD-T (where the hyphens denote caspase cleavage sites). Through functional and mechanistic studies, we show that upon DDD cleavage by Caspase-3, the resulting DEVD-T peptide acts as a competitive inhibitor and entraps the active site of Caspase-3 akin to DEVD-CHO, which is a potent, synthetic inhibitor of Caspase-3 activity. By gain and loss-of-function studies using restoration of DDD expression in DDD deficient hepatocytic cells, we found that both Caspase-3 sites in DDD are necessary for inhibition of Caspase-3 and promotion of cell survival. Employing mutagenesis studies, we show that DDD could operate independently of Met’s enzymatic activity as determined by using kinase-dead human Met mutant constructs. Studies of both human liver cancer tissues and cell lines uncovered that DDD cleavage and entrapment of Caspase-3 by DDD occur in vivo, further proving that this site has physiological and pathophysiological relevance. Our findings show that Met can directly inhibit Caspase-3 via a novel mechanism and promote hepato-cyte survival. Results presented here will further our understanding of the mechanisms that control not only normal tissue homeostasis but also abnormal tissue growth such as cancer and degenerative diseases in which apoptotic caspases are at play.
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影响因子：
8
作者：
Seol, DW;Chen, QY;Zarnegar, R
通讯作者：
Zarnegar, R
影响因子：
7.8
作者：
ZARNEGAR, R;MICHALOPOULOS, GK
通讯作者：
MICHALOPOULOS, GK
影响因子：
16
作者：
Wang, X;DeFrances, MC;Zarneger, R
通讯作者：
Zarneger, R
影响因子：
4
作者：
Dai, James Y.;DeFrances, Marie C.;Zou, Chunbin;Johnson, Carla J.;Zarnegar, Reza
通讯作者：
Zarnegar, Reza
影响因子：
4.8
作者：
Dobo, Jozsef;Swanson, Richard;Gettins, Peter G. W.
通讯作者：
Gettins, Peter G. W.