Molecular Basis For Functional Diversity Of PSGL-1

描述（申请人描述）：白细胞募集的调节 进入炎症部位发生在白细胞识别水平， 内皮细胞这一关键事件是由 粘附分子选择素家族及其白细胞和内皮细胞 表达的配体。该建议旨在理解蜂窝和 P-选择素糖蛋白配体1介导粘附的分子基础 （PSGL-1）。这种粘附分子在所有类型的白细胞上表达， 主要介导对内皮或血小板P-选择素的粘附，但也 介导与白细胞L-选择素的相互作用。因此，PSGL- 1是必不可少的， 白细胞识别其他白细胞、血小板和内皮细胞，以及 在白细胞向内皮的募集中起主要作用， 炎症反应的放大。PSGL-1的许多功能 已经描述了这些相互作用所需的胞外域，我们已经 最近表明，PSGL-1胞质结构域和细胞质结构域之间的相互作用， 肌动蛋白细胞骨架通过连接蛋白膜突蛋白，是必不可少的结合 P-选择素PSGL- 1也作为病原体的进入受体 人类粒细胞埃里希体病（HGE）。HOE是一个最近 描述了人类的蜱传感染， 循环中性粒细胞HGE细菌与PSGL-1的区域结合， 或与P-选择素结合区重叠，但不知道其特征 细菌的结合和随后的进入需要这些结合位点。 在这份提案中，我们希望进一步了解 PSGL-1与P-选择素和HGE的相互作用通过：1）鉴定PSGL-1内的残基， PSGL- 1的胞质结构域负责细胞骨架附着， 细胞粘附; 2）确定细胞间相互作用的功能重要性， 膜突蛋白和PSGL- 1的胞质结构域;以及3）定义膜突蛋白的生物化学结构域。 HOE细菌结合和进入所需的PSGL-1特征。这些研究 这将极大地增强我们对PSGL- 1的基本组成部分的理解 与选择素和细胞内寄生虫相互作用所必需的。 从探索这些具体的施舍中获得的综合信息将增加 对我们理解PSGL- 1的功能有重要意义， 确定急性和慢性疾病干预的新临床靶点 炎性病症、HGE的预防和/或治疗以及 其他涉及免疫系统的疾病。

DESCRIPTION (applicant's description): The regulation of leukocyte recruitment into inflammatory sites occurs at the level of leukocyte recognition of endothelium. This crucial event is mediated by interactions between the selectin family of adhesion molecules and their leukocyte and endothelial expressed ligands. This proposal is directed at understanding the cellular and molecular basis of adhesion mediated by P-selectin Glycoprotein Ligand-1 (PSGL-l). This adhesion molecule is expressed on all classes of leukocytes and mediates adhesion primarily to endothelial or platelet P-selectin, but also mediates interactions with leukocyte L-selectin. Thus, PSGL- 1 is essential for leukocyte recognition of other leukocytes, platelets, and endothelium, and plays a major role in the recruitment of leukocytes to endothelium and amplification of the inflammatory response. Many features of the PSGL-1 ectodomain required for these interactions have been described, and we have recently shown that interactions between the PSGL-l cytoplasmic domain and the actin cytoskeleton via the linker protein moesin, are essential for binding to P-selectin. PSGL- 1 also serves as the entry receptor for the pathogen responsible for Human Granulocytic Ehrlichiosis (HGE). HOE is a recently described tick-borne infection of humans which infects and proliferates within circulating neutrophils. HGE bacterium bind to an area of PSGL-1 identical to or overlapping the P-selectin binding region, but it is not known what features of this binding site are required for bacterial binding and subsequent entry. In this proposal, we hope to further understand the structural requirements of PSGL-1 interactions with P-selectin and HGE by: 1) identifying residues within the cytoplasmic domain of PSGL- 1 responsible for cytoskeletal attachment and cell adhesion; 2) determining the functional importance of interactions between moesin and the cytoplasmic domain of PSGL- 1; and 3) defining the biochemical features of PSGL-1 required for HOE bacterium binding and entry. These studies should greatly enhance our understanding of the essential components of PSGL- 1 required for interactions with both selectins and an intracellular parasite. The combined information gained from exploring these specific alms will add significantly to our understanding of how PSGL- 1 functions, and should identify new clinical targets for intervention in acute and chronic inflammatory disorders, prevention and/or treatment of HGE, and treatment of other diseases involving the immune system.