Grimm S, Stanger B Z, Leder P
Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.
Proc Natl Acad Sci U S A. 1996 Oct 1;93(20):10923-7. doi: 10.1073/pnas.93.20.10923.
With use of the yeast two-hybrid system, the proteins RIP and FADD/MORT1 have been shown to interact with the "death domain" of the Fas receptor. Both of these proteins induce apoptosis in mammalian cells. Using receptor fusion constructs, we provide evidence that the self-association of the death domain of RIP by itself is sufficient to elicit apoptosis. However, both the death domain and the adjacent alpha-helical region of RIP are required for the optimal cell killing induced by the overexpression of this gene. By contrast, FADD's ability to induce cell death does not depend on crosslinking. Furthermore, RIP and FADD appear to activate different apoptotic pathways since RIP is able to induce cell death in a cell line that is resistant to the apoptotic effects of Fas, tumor necrosis factor, and FADD. Consistent with this, a dominant negative mutant of FADD, lacking its N-terminal domain, blocks apoptosis induced by RIP but not by FADD. Since both pathways are blocked by CrmA, the interleukin 1 beta converting enzyme family protease inhibitor, these results suggest that FADD and RIP can act along separable pathways that nonetheless converge on a member of the interleukin 1 beta converting enzyme family of cysteine proteases.
利用酵母双杂交系统，已证明RIP蛋白和FADD/MORT1蛋白可与Fas受体的“死亡结构域”相互作用。这两种蛋白均可在哺乳动物细胞中诱导凋亡。通过使用受体融合构建体，我们提供了证据表明RIP死亡结构域自身的自缔合足以引发凋亡。然而，RIP的死亡结构域和相邻的α螺旋区域对于该基因过表达诱导的最佳细胞杀伤都是必需的。相比之下，FADD诱导细胞死亡的能力并不依赖于交联。此外，RIP和FADD似乎激活不同的凋亡途径，因为RIP能够在对Fas、肿瘤坏死因子和FADD的凋亡作用具有抗性的细胞系中诱导细胞死亡。与此一致的是，缺失其N端结构域的FADD显性负性突变体可阻断RIP诱导的凋亡，但不阻断FADD诱导的凋亡。由于这两种途径均被白细胞介素1β转换酶家族蛋白酶抑制剂CrmA阻断，这些结果表明FADD和RIP可沿着可分离的途径发挥作用，尽管如此，它们最终都会汇聚到白细胞介素1β转换酶家族半胱氨酸蛋白酶的一个成员上。
