Role of HIV Tat protein in pathogenesis of HIV dementia

描述（由申请人提供）：目前的抗逆转录病毒治疗是在HIV已经进入大脑时进行免疫抑制。此外，这种治疗方式对整合的病毒或早期病毒基因转录物如达特、Nef和Rev的产生没有影响。在这些基因产物中，只有达特被释放到细胞外，并对神经元和神经胶质细胞具有多种作用。迄今为止，大多数研究仅通过1或2种来源于HIV进化枝B的达特蛋白进行，但进化枝B和C来源的达特蛋白之间的氨基酸序列存在显著差异，甚至在基因的所谓保守区中也是如此。此外，HIV进化枝C病毒感染了世界上最大的人群，有趣的是，在进化枝C感染的国家很少或没有痴呆症的报道。虽然可能有多种原因导致差异，但对来自进化枝C的达特的功能性质知之甚少。此外，进化枝B和C的第二外显子的作用知之甚少。达特还具有经历翻译后修饰的残基，其功能意义需要表征。由于达特在HIV复制中的关键作用及其对脑细胞的作用，需要建立靶向这种蛋白质或在介导达特作用中关键的宿主因子的治疗方法。因此，我们建议1）确定HIV进化枝特异性差异的达特对脑细胞的影响。达特将从充分表征的HIV进化枝B和C感染患者的脑和脾中测序。将比较重组达特蛋白和表达达特的细胞系的功能差异。2)确定介导达特对脑细胞的作用所必需的达特的物理性质。参与翻译后修饰的氨基酸将被突变以确定它们在达特功能中的作用。3)鉴定靶向达特介导的对脑细胞的作用的新的治疗方法。将筛选靶向与达特相互作用的宿主蛋白质的批准用于人类的药物，以确定它们对进化枝B和C衍生的达特蛋白质的治疗潜力。

DESCRIPTION (provided by applicant): Current antiretroviral therapy is instituted upon immunosuppression when HIV has already entered the brain. Further, this mode of treatment has no effect on the integrated virus or on the production of early viral gene transcripts such as Tat, Nef and Rev. Of these gene products, only Tat is released extracellularly and has a variety of effects on neurons and glial cells. To date, most studies have been performed by only 1 or 2 Tat proteins derived from HIV clade B, but there is significant divergence in the amino acid sequences between clade B and C derived Tat proteins, even in the so called conserved regions of the gene. Further, HIV clade C virus infects the largest populations in the world, and interestingly little or no dementia has been reported from the clade C infected countries. Although there may be multiple reasons for the differences, very little is known about the functional properties of Tat derived from clade C. Further, the role of the second exon of both clade B and C is poorly understood. Tat also has residues that undergo post-translational modification the functional significance of needs to be characterized. Because of the critical role of Tat in HIV replication and its effects on brain cells, there is need to establish therapeutic approaches that would target this protein or host factors that are critical in mediating Tat effects. We thus propose to 1) determine HIV clade specific differences in Tat effects on brain cells. Tat will be sequenced from brain and spleen from well-characterized patients with HIV clade B and C infections. Recombinant Tat proteins and Tat expressing cell lines will be compared for their functional differences. 2) determine physical properties of Tat necessary for mediating Tat effects on brain cells. The amino acids involved in posttranslational modification will be mutated to determine their role in Tat function. 3) identify novel therapeutic approaches for targeting Tat mediated effects on brain cells. Drugs approved for human use targeted against host proteins that interact with Tat will be screened to determine their therapeutic potential against clade B and C derived Tat proteins.