Molecular Regulation of Inhibitory Killer Cell Ig-like Receptors

描述（由申请人提供）：杀伤细胞igg样受体（KIR）的抑制形式是人类自然杀伤（NK）细胞激活的重要负调节因子。它们通过识别体内正常细胞表面的MHC I类分子（HLA-A， -B和-C）来维持NK细胞的耐受性。KIR通过募集SHP-1和SHP-2酪氨酸磷酸酶来传递抑制信号。由于NK细胞的激活是由激活受体和抑制受体之间的平衡控制的，因此KIR的表面表达水平是NK细胞激活电位的关键决定因素。虽然大量的努力都是为了理解KIR转导抑制信号的机制，但对这些受体的表面表达、内吞作用和质膜运输的翻译后机制知之甚少。进一步了解KIR表面转运和表达的调控机制，可以通过降低KIR的表面表达水平，为促进NK细胞对肿瘤和病毒感染细胞的激活提供新的治疗靶点。我们将通过解决以下具体目标来定义调节抑制性KIR贩运的分子机制。目的1将评估配体在调节抑制性KIR表面表达中的作用。在这里，我们将检验配体接合影响抑制KIR的膜运输的假设。目的2将阐明介导抑制KIR的内吞和降解的分子机制。我们假设某些分子相互作用控制着这些途径，我们的实验将测试它们对表面受体表达的影响。目的3将研究b捕集蛋白2接头蛋白在抑制性KIR表面转运中的作用。我们假设这种接头促进KIR的表面表达，并稳定受体与SHP-1和SHP-2磷酸酶的相互作用。

DESCRIPTION (provided by applicant): Inhibitory forms of killer cell Ig-like receptors (KIR) are important negative regulators of human natural killer (NK) cell activation. They maintain NK cell tolerance through recognition of MHC class I molecules (HLA-A, -B, and -C) on the surface of normal cells in the body. KIR transduces inhibitory signals through the recruitment of SHP-1 and SHP-2 tyrosine phosphatases. Since NK cell activation is controlled by a balance between activating and inhibitory receptors, the surface expression level of KIR is a key determinant of the NK cell activation potential. While a great deal of effort has been directed toward understanding the mechanism by which KIR transduces inhibitory signals, very little is known about the post-translational mechanisms regulating surface expression, endocytosis, and plasma membrane trafficking of these receptors. Improved understanding of the mechanisms regulating KIR surface trafficking and expression could provide novel therapeutic targets to promote NK cell activation toward tumors and virus infected cells by reducing the surface expression levels of KIR. We will define the molecular mechanisms regulating inhibitory KIR trafficking by addressing the following specific aims. Aim 1 will assess the role of ligand in regulating surface expression of inhibitory KIR. Here we will test the hypothesis that ligand engagement impacts upon the membrane trafficking of inhibitory KIR. Aim 2 will elucidate the molecular mechanisms mediating endocytosis and degradation of inhibitory KIR. We hypothesize that certain molecular interactions control these pathways, and our experiments will test their impacts on surface receptor expression. Aim 3 will examine the role of the b arrestin 2 adaptor protein on surface trafficking of inhibitory KIR. We hypothesize that this adaptor promotes surface expression of KIR and stabilizes interaction of the receptor with SHP-1 and SHP-2 phosphatases. PUBLIC HEALTH RELEVANCE: Natural killer (NK) cells can attack tumors and virus-infected cells, and their activation state is controlled by a balance of signals from activating and inhibitory receptors. Inhibitory killer cell Ig-like receptors (KIR) are key regulators on human NK cells that establish tolerance toward normal cells of the body, but surprisingly little is known about the mechanisms that maintain their surface expression. The studies proposed in this application will characterize the molecular regulation of KIR membrane trafficking to develop strategies for reducing their surface expression and thereby potentiating NK cell responses toward tumors and viruses.