相关专题 细胞凋亡专题

Caspase是一类对天冬氨酸特异的半胱氨酸蛋白酶，是与秀丽隐杆线虫Ced一3具有序列和结构同源性的一个蛋白家族，在细胞凋亡 执行过程中直接参与早期凋亡启动、信号传递及晚期凋亡效应，除此之外，部分caspase在细胞分化、细胞增殖、细胞移动中也发挥着作用。

Apoptosis, programmed cell death, is triggered by a variety of stimuli, including cell surface receptors like FAS, mitochondrial response to stress, and cytotoxic T cells. Caspases are a class of cysteine proteases that includes several representatives involved in apoptosis. The caspases convey the apoptotic signal in a proteolytic cascade, with caspases cleaving and activating other caspases that then degrade other cellular targets that lead to cell death. The caspases at the upper end of the cascade include caspase-8 and caspase-9. Caspase-8 is the initial caspase involved in response to receptors with a death domain like FAS. The mitochondrial stress pathway begins with the release of cytochrome c from mitochondria, which then interacts with Apaf-1, causing self-cleavage and activation of caspase-9. Caspase-3, -6 and-7 are downstream caspases that are activated by the upstream proteases and act themselves to cleave cellular targets. Granzyme B and perforin proteins released by cytotoxic T cells induce apoptosis in target cells, forming transmembrane pores, and triggering apoptosis, perhaps through cleavage of caspases, although caspase-independent mechanisms of Granzyme B mediated apoptosis have been suggested.