Procaspase 8 Activation by HIV Protease

描述（由申请人提供）：关于直接感染HIV的CD4+ T细胞如何在感染后死亡仍然存在争议。已经提出了许多机制来解释感染细胞的杀伤，但是没有一种提出的机制被普遍接受。人们早就认识到，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，然而，HIV蛋白酶是如何杀死这些细胞的尚不清楚。实验数据表明，除了病毒蛋白外，HIV蛋白酶还能切割宿主细胞蛋白。我们的实验室最近确定了HIV蛋白酶杀死细胞的一种机制；具体来说，HIV蛋白酶可以裂解凋亡启动蛋白procaspase 8，从而使其活化。随后，一个传统的细胞凋亡级联被启动，最终导致与细胞凋亡相关的结构、核和形态学改变。虽然我们已经证明这种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。当前建议的重点是确定这种形式的细胞杀死在试管中发生的感染和患者中的相关性。这项研究的临床意义可能反映在最近的临床观察中，表明感染HIV的患者与不感染HIV的患者相比，在HIV蛋白酶基因中含有突变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.