Procaspase 8 Activation by HIV Protease

描述（由申请人提供）：关于直接感染HIV的CD 4 + T细胞在感染后如何死亡仍然存在争议。已经提出了许多机制来解释感染的细胞杀伤，然而没有一种提出的机制被普遍接受。长期以来，人们已经认识到一种HIV蛋白，HIV蛋白酶，本质上是细胞毒性的，因为它的表达会导致细菌，酵母和哺乳动物细胞的死亡，但仍不清楚HIV蛋白酶如何杀死这些细胞。实验数据现在证明，HIV蛋白酶除了切割病毒蛋白外，还切割宿主细胞蛋白。我们的实验室最近确定了一种HIV蛋白酶可以杀死细胞的机制;特别是HIV蛋白酶可以切割凋亡起始蛋白，procaspase 8，导致其激活。此后，启动传统的凋亡级联反应，最终导致与凋亡相关的结构、核和形态学变化。虽然我们已经证明了这种HIV蛋白酶介导的杀伤机制可以发生，但我们还没有确定这种机制是否确实发生，特别是在体内。目前提案的重点是确定这种形式的细胞杀伤在试管中发生的感染以及患者中的相关性。这项研究的临床意义可能反映在最近的临床观察中，表明与那些不含HIV蛋白酶基因突变的患者相比，感染HIV的患者的病程发生了改变。我们将通过评估野生型HIV蛋白酶与突变型蛋白酶对procaspase 8激活和细胞杀伤的差异影响来探索这些突变的潜在影响。

DESCRIPTION (provided by applicant): It remains controversial as to how CD4+ T cells directly infected with HIV die following infection. Numerous mechanisms have been proposed to account for infected cell killing, however none of the proposed mechanisms are universally accepted. It has long been recognized that one HIV protein, HIV protease, is intrinsically cytotoxic as its expression causes the death of bacteria, yeast, and mammalian cells, however it remains unclear how HIV protease kills these cells. Experimental data now demonstrate that HIV protease cleaves host cell proteins in addition to viral proteins. Our laboratory has recently defined one mechanism by which HIV protease can kill cells; specifically HIV protease can cleave the apoptosis initiating protein, procaspase 8, to result in its activation. Thereafter, a traditional apoptosis cascade is initiated, ultimately resulting in the structural, nuclear, and morphologic changes associated with apoptosis. While we have demonstrated that this mechanism of HIV protease mediated killing can occur, we have yet to determine whether or not this mechanism does occur, particularly in vivo. The focus of the current proposal is to define the relevance of this form of cell killing both in infections, which occur in the test tube, as well as in patients. The clinical significance of this research may be reflected in recent clinical observations, suggesting an altered diseased course of patients who have infections with HIV that contain mutations within the HIV protease gene as compared to those that do not. We will explore the potential impact of these mutations by assessing the differential impact of wild type HIV protease versus mutant protease on procaspase 8 activation and cell killing.