Suzuki A, Iwasaki M, Wagai N
Drug Safety Research Laboratory, Daiichi Pharmaceutical Co., Ltd, Tokyo R&D center, Edogawa-ku, Japan.
Exp Cell Res. 1997 May 25;233(1):48-55. doi: 10.1006/excr.1997.3546.
On stimulation by the Fas ligand, the death receptor, Fas, initiates a signal leading to apoptotic cell death. Fas plays an important role in physiological cell death and is closely involved in various disease states. Recent investigations have shown that caspase 3 plays a dominant role in the process of Fas-mediated apoptosis. In the present study, we investigated the molecular machinery of caspase 3 activation in Fas-mediated apoptosis. The results showed that Fas-mediated apoptosis was accompanied by caspase 3 activation, and both Fas-mediated apoptosis and caspase 3 activation were prevented by a serine proteinase inhibitor. In addition, the serine proteinase inhibitor also prevented the caspase 3 activation in cytoplasts, and the specific activation of serineproteinase was encountered in only cytoplasmic proteins. These results suggest that cytoplasmic serineproteinase plays an important role in caspase 3 activation. Interestingly, caspase 3 was cleaved at p3 site immediately after Fas Ab stimulation, and the cleavage at p17 site became detectable later. We also found that among tested proteinases only Staphylococcus aureus V8 serineproteinase initiated caspase 3 activation and specifically cleaved at p3 site. These results strongly suggest that a cytoplasmic S. aureus V8-like serine proteinase is closely involved in caspase 3 activation.
在受到Fas配体刺激时，死亡受体Fas会启动一个导致细胞凋亡的信号。Fas在生理性细胞死亡中起重要作用，并与多种疾病状态密切相关。最近的研究表明，半胱天冬酶3在Fas介导的细胞凋亡过程中起主导作用。在本研究中，我们调查了Fas介导的细胞凋亡中半胱天冬酶3激活的分子机制。结果显示，Fas介导的细胞凋亡伴随着半胱天冬酶3的激活，并且丝氨酸蛋白酶抑制剂可阻止Fas介导的细胞凋亡和半胱天冬酶3的激活。此外，丝氨酸蛋白酶抑制剂还可阻止胞质体中的半胱天冬酶3激活，并且仅在细胞质蛋白中发现丝氨酸蛋白酶的特异性激活。这些结果表明，细胞质丝氨酸蛋白酶在半胱天冬酶3激活中起重要作用。有趣的是，在Fas抗体刺激后，半胱天冬酶3立即在p3位点被切割，而在p17位点的切割稍后才变得可检测到。我们还发现，在测试的蛋白酶中，只有金黄色葡萄球菌V8丝氨酸蛋白酶启动半胱天冬酶3激活并特异性地在p3位点切割。这些结果强烈表明，一种细胞质的类金黄色葡萄球菌V8丝氨酸蛋白酶与半胱天冬酶3激活密切相关。
