AIF-1 Expression in VSMC Growth and Arteriopathy

描述(申请人提供)：作为VSMC对损伤的反应的一部分，VSMC迁移到血管的管腔中，在那里它们增殖并合成细胞因子，它们以自分泌的方式对其做出反应，从而维持管腔直径的损失。在HL63810的过程中，我们已经确定，异体移植物炎症因子-1(AIF-1)是一种新发现的胞浆钙结合蛋白，可以预测临床移植血管病变的发展。AIF-1在损伤的颈动脉中的表达显著加剧了管腔直径的减少，并将骨髓细胞重新聚集到外膜。下调AIF-1基因可抑制新生内膜增生。AIF-1在人VSMC中的表达促进了VSMC的迁移和增殖，诱导了G-CSF的表达，并激活了Pad GTP酶。AIF-1含有多个信号域，与肌动蛋白结合并聚合，激活信号转导蛋白。我们的数据支持我们的中心假设，即AIF-1是一种炎症反应支架蛋白，在调节VSMC激活和新生内膜增生的发展中发挥关键作用。该应用的总体目标是1-确定AIF-1表达与体内新生内膜增生之间的因果关系，以及2-表征VSMC中AIF-1活性的细胞途径和分子机制。已经形成了三个目标来检验假设：1-AIF-1的表达加剧了新生内膜的增殖，并且降低AIF-1的表达将减少血管成形术损伤大鼠和AIF-1转基因小鼠的新生内膜增生；2-AIF-1直接激活了导致G-CSF表达的rac1信号通路，AIF-1直接激活了G-CSF的表达并随后自分泌激活了RAC信号通路；3-AIF-1通过激活GEF激活了rac1，并通过激活转录因子诱导了G-CSF的表达。对AIF-1功能的研究将澄清我们对炎症介导的信号转导导致VSMC病理生物学和血管免疫细胞串扰的理解。

DESCRIPTION (provided by applicant): As part of the VSMC response to injury, VSMC migrate into the lumen of the vessel where they proliferate and synthesize cytokines which they respond to in an autocrine fashion, sustaining the loss of lumen diameter. In the course of HL63810, we have determined that expression of Allograft Inflammatory Factor-1 (AIF-1), a newly described cytoplasmic, calcium-binding protein, is predictive of development of clinical transplant vasculopathy. Expression of AIF-1 in injured carotid artery significantly exacerbates reduction of lumen diameter and recruits bone marrow cells to the adventitia. Knock-down of AIF-1 abrogates neointimal hyperplasia. Expression of AIF-1 in human VSMC increases migration, proliferation, induces expression of G-CSF, and activates the Pad GTPase. AIF-1 contains several signaling domains, binds to and polymerizes actin, and activates signal transduction proteins. Our data support our central hypothesis that AIF-1 is an inflammation-responsive scaffold protein that plays a key role in regulation of VSMC activation and development of neointimal hyperplasia. The overall goals of this application are to 1- determine a cause and effect relationship between AIF-1 expression and neointimal hyperplasia in vivo, and 2- characterize the cellular pathways and molecular mechanisms responsible for AIF-1 activity in VSMC. Three aims have been formulated to test the hypothesis that; 1- AIF-1 expression exacerbates neointimal hyperplasia, and that reduction of AIF-1 expression will reduce neointimal hyperplasia in angioplasty-injured rats and AIF-1 transgenic mice, 2- that AIF-1 directly activates Rac1 signaling pathways leading to G-CSF expression, and that AIF-1 directly activates G-CSF expression with a subsequent autocrine activation of the Rac signaling pathway, and 3- AIF-1 activates Rac1 by activation of GEFs, and induces G-CSF expression by activation of transcription factors. Characterization of AIF-1 function will clarify our understanding of inflammation-mediated signal transduction leading to VSMC pathobiology and vascular- immune cell cross talk.