Davis J E, Sutton V R, Smyth M J, Trapani J A
John Connell Laboratory, The Austin Research Institute, Studley Road, Heidelberg, 3084, Australia.
Cell Death Differ. 2000 Oct;7(10):973-83. doi: 10.1038/sj.cdd.4400725.
The molecular pathways responsible for apoptosis in response to granzyme B have remained unresolved. Here we present data supporting the notion that granzyme B-mediated cell death is largely dependent on a pathway that is inhibitable by Bcl-2 or its viral analog BHRF1. We used a panel of stably transfected FDC-P1 mouse myeloid cell lines to show that overexpression of functional, wild-type Bcl-2 or BHRF1 rescued cells from granzyme B-mediated apoptosis, whereas mutated (Gly145-->Glu) Bcl-2, or wild-type Bcl-2 directed to the plasma membrane conferred no protection. Overexpression of Bcl-2 resulted in inhibition of multiple parameters of apoptosis in response to purified perforin and granzyme B, including DNA fragmentation, changes in light scatter profile indicating cell shrinkage and increased refractivity, loss of mitochondrial membrane potential and inhibited colony formation in clonogenic assays. Nevertheless, when exposed to cytotoxic lymphocytes, FDC-P1 and YAC-1 cells overexpressing Bcl-2 remained susceptible to death imparted by cytolytic granules, irrespective of whether the granules contained granzyme B. Thus, alternative granzyme B-independent pathways can be activated by intact lymphocytes to overcome Bcl-2-like inhibitors of apoptosis, enabling CTLs to overcome potential viral blocks to granzyme B-mediated cell death.
响应颗粒酶B而引发细胞凋亡的分子途径仍未明确。在此，我们提供的数据支持这样一种观点，即颗粒酶B介导的细胞死亡很大程度上依赖于一条可被Bcl-2或其病毒类似物BHRF1抑制的途径。我们使用了一组稳定转染的FDC-P1小鼠髓样细胞系，以表明功能性野生型Bcl-2或BHRF1的过表达可使细胞免受颗粒酶B介导的细胞凋亡，而突变型（Gly145→Glu）Bcl-2或定位于质膜的野生型Bcl-2则没有保护作用。Bcl-2的过表达导致对纯化的穿孔素和颗粒酶B响应的多个细胞凋亡参数受到抑制，包括DNA片段化、表明细胞收缩和折光率增加的光散射图谱变化、线粒体膜电位丧失以及克隆形成试验中集落形成受到抑制。然而，当暴露于细胞毒性淋巴细胞时，过表达Bcl-2的FDC-P1和YAC-1细胞仍然易受溶细胞颗粒导致的死亡影响，无论这些颗粒是否含有颗粒酶B。因此，完整的淋巴细胞可激活替代的不依赖颗粒酶B的途径，以克服Bcl-2样凋亡抑制剂的作用，使细胞毒性T淋巴细胞能够克服病毒对颗粒酶B介导的细胞死亡的潜在阻断。
