The Role of Presenilins in HIV Associated Dementia

描述（由申请人提供）：HIV相关痴呆（HAD）是认知能力下降的重要且潜在可治疗的原因。尽管随着高效抗逆转录病毒疗法（HAART）的出现，艾滋病死亡率有所降低，但HAD的流行率正在上升。对HAD和其他神经退行性疾病（如阿尔茨海默病（AD））患者的脑组织进行神经病理学研究，发现了显著的神经炎症改变的证据，包括小胶质细胞（大脑免疫细胞）的激活。早老素蛋白（PS）、早老素1 （PS1）和早老素2 （PS2）编码基因的突变导致家族性AD，因此早老素1是神经退行性疾病研究的自然焦点。PS是y分泌酶复合物的催化成分，y分泌酶复合物是一种膜蛋白酶，可将淀粉样肽蛋白加工成淀粉样β肽，存在于AD斑块中。PS y-分泌酶复合体也切割许多底物，如ErbB4、Notch、p75，这些底物与炎症过程有关。先前的研究表明PS在中枢神经系统炎症中的作用，我们的初步数据表明PS2蛋白在HAD脑和受HIV外壳蛋白gp120刺激的小胶质细胞中增加。在本K08职业发展建议中，我们假设PS是HAD中神经炎症过程的组成部分。在获奖期间，研究者将研究由HIV外壳蛋白gp120激活的小胶质细胞中药理y分泌酶抑制和shRNA敲低PS的影响。PS2敲除小鼠的原代小胶质细胞将被检测gp120诱导的激活。利用免疫组织化学，我们将研究与小胶质细胞炎症反应有关的两种y分泌酶底物ErbB4和p75NTR在HAD脑中的细胞类型和亚细胞表达。我们将使用共免疫沉淀法确定已知的y分泌酶成分是否在小胶质细胞中聚集，并测量小胶质细胞y分泌酶活性对炎症刺激的反应。众所周知，PS介导的细胞功能独立于y分泌酶复合物，因此我们将采用蛋白质组学技术在静止和gp120刺激的小胶质细胞中鉴定新的PS结合伙伴。一个多学科的方法，包括指导的板凳研究，教学，研讨会和专业会议将提供必要的培训环境，以促进这名年轻的研究者发展成为一个独立的临床科学家。对个人、家庭和卫生保健系统来说，HAD是一个昂贵的负担。这一建议将有助于对HIV诱导的神经炎症机制的基本理解，这将有可能导致更有效的治疗HAD的治疗方法。

DESCRIPTION (provided by applicant): HIV associated dementia (HAD) is a significant and potentially treatable cause of cognitive decline. Despite improved AIDS mortality rates with the advent of highly active anti-retroviral therapy (HAART), the prevalence of HAD is increasing. Neuropathological studies of brain tissue from patients with HAD and other neurodegenerative diseases such as Alzheimer's disease (AD), reveal evidence of prominent neuroinflammatory changes including activation of microglia, the resident brain immune cells. Mutations in the genes coding for the presenilin proteins (PS), presenilin 1 (PS1) and presenilin 2 (PS2) cause familial AD, and thus PS are a natural focus of study in neurodegenerative disease. PS are the catalytic component of the y-secretase complex, a membrane protease that processes amyloid peptide protein to form amyloid beta peptide, found in AD plaques. The PS y-secretase complex also cleaves numerous substrates such as ErbB4, Notch, p75 that have been implicated in inflammatory processes. Previous work suggests a role for PS in central nervous system inflammation and our preliminary data demonstrate that PS2 protein is increased in HAD brain as well as in microglia stimulated by the HIV coat protein, gp120. In this K08 career development proposal, we hypothesize that PS are integral to the neuroinflammatory processes in HAD. During the award period the investigator will study the effects of pharmacological y-secretase inhibition and shRNA knock down of PS in microglia activated by the HIV coat protein, gp120. Primary microglia from PS2 knockout mice will be assayed for gp120 induced activation. Using immunohistochemistry we will investigate cell type and sub-cellular expression in HAD brain of two Y-secretase substrates implicated in the microglia inflammatory response, ErbB4 and p75NTR. We will determine if the known y-secretase components assemble in microglia using co-immunoprecipitation and measure microglia y-secretase activity in response to inflammatory stimuli. PS are known to mediate cellular functions independent of the y-secretase complex, and therefore we will employ proteomic techniques to identify novel PS binding partners in quiescent and gp120 stimulated microglia. A multidisciplinary approach including mentored bench research, didactics, seminars and professional conferences will provide the necessary training environment to promote the development of this young investigator into an independent clinician-scientist. HAD is a costly burden to individuals, families and the health care system. This proposal will contribute to the fundamental understanding of mechanisms in HIV induced neuroinflammation that will potentially lead to more effective therapeutics in the treatment of HAD.