Jones B, Roberts P J, Faubion W A, Kominami E, Gores G J
Center for Basic Research in Digestive Diseases, Mayo Clinic, Rochester, Minnesota 55905, USA.
Am J Physiol. 1998 Oct;275(4):G723-30. doi: 10.1152/ajpgi.1998.275.4.G723.
We have previously demonstrated abrogation of bile salt-induced apoptosis by cathepsin B inhibitors. However, caspases have been strongly implicated in apoptosis, and the mechanistic interface between caspase and cathepsin B activation is unclear. Thus our aims were to determine the mechanistic relationship between caspases and cathepsin B in bile salt-induced apoptosis in a rat hepatoma cell line. Expression of cystatin A was used to inhibit cathepsin B, whereas Z-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK) was used to inhibit caspases. Cystatin A expression prevented cathepsin B activation and apoptosis during treatment with glycochenodeoxycholate (GCDC), a toxic bile salt. Caspase N-acetyl-Asp-Glu-Val-Asp-7-amino-4-methylcoumarin (DEVD-AMC) hydrolytic activity increased in both wild-type and cystatin A-transfected cells treated with GCDC, demonstrating caspase activation despite inhibition of cathepsin B. In contrast, Z-VAD-FMK blocked both DEVD-AMC hydrolytic activity and cathepsin B activity during GCDC treatment. Our data demonstrate that 1) bile salt-induced apoptosis can be inhibited by the cystatin A transgene and 2) caspase and cathepsin B activation are linked mechanistically with cathepsin B downstream of caspases.
我们之前已经证明组织蛋白酶B抑制剂可消除胆盐诱导的细胞凋亡。然而，半胱天冬酶与细胞凋亡密切相关，而半胱天冬酶和组织蛋白酶B激活之间的机制联系尚不清楚。因此，我们的目的是确定在大鼠肝癌细胞系中，半胱天冬酶与组织蛋白酶B在胆盐诱导的细胞凋亡中的机制关系。使用胱抑素A的表达来抑制组织蛋白酶B，而使用Z-缬氨酸-丙氨酸-天冬氨酸-氟甲基酮（Z-VAD-FMK）来抑制半胱天冬酶。在用毒性胆盐甘氨鹅去氧胆酸（GCDC）处理期间，胱抑素A的表达可防止组织蛋白酶B激活和细胞凋亡。在用GCDC处理的野生型和转染了胱抑素A的细胞中，半胱天冬酶N-乙酰-天冬氨酸-谷氨酸-缬氨酸-天冬氨酸-7-氨基-4-甲基香豆素（DEVD-AMC）水解活性均增加，这表明尽管组织蛋白酶B受到抑制，但半胱天冬酶仍被激活。相比之下，在GCDC处理期间，Z-VAD-FMK同时阻断了DEVD-AMC水解活性和组织蛋白酶B活性。我们的数据表明：1）胱抑素A转基因可抑制胆盐诱导的细胞凋亡；2）半胱天冬酶和组织蛋白酶B的激活在机制上与半胱天冬酶下游的组织蛋白酶B相关联。
