Requirement of TNFR p75 in ischemia-induced angiogenesis

描述（由申请人提供）：背景：衰老是冠状动脉和外周动脉疾病发生的危险因素。在血管化广泛受损的情况下，缺血性损伤和功能恢复的程度在很大程度上取决于新的侧支血管的发展。肿瘤坏死因子α（TNF-α）是一种巨噬细胞/单核细胞衍生的多能介质和促炎细胞因子，在缺血区域表达，并据报道诱导血管生成。据报道，TNF通过两种不同的TNF受体TNFR 1（p55）和TNFR 2（p75）诱导许多血管生成相关基因的表达。在多种血管内皮细胞中，TNF可增加血管生成因子VEGF、bFGF、IL-8的表达，但两种不同的TNF受体在介导这些反应中的作用尚不清楚。假设：p55在很大程度上已知介导TNF的细胞毒性作用，而通过p75的信号传导主要暗示TNF-α的保护作用，并且由于衰老与来自老年人的细胞中p55表达增加和p75表达减少相关，我们假设p75可能在成人的血管生成信号传导中是必需的。目的：1）确定TNFR 2 p75对VEGF和bFGF基因表达对体外EC功能和体内血管生成的贡献; TNF诱导的促血管生成信号传导和EC功能在很大程度上通过p75 TNFR 2介导。2)确定肿瘤坏死因子介导的缺血诱导内皮细胞存活和凋亡信号传导的分子机制;在缺乏TNFR 2 p75的情况下，缺血后凋亡信号传导被夸大。3)确定缺血诱导的EPC从骨髓的动员、迁移和募集在多大程度上依赖于通过p75 TNFR 2的信号传导; a）缺血诱导的EPC从骨髓的动员至少部分地通过TNFR 2 p75介导; B）功能性TNFR 2 p75对于骨髓来源的EPC对缺血后恢复的适当贡献是必需的。重要性：该建议的目的是确定缺血诱导的TNF-介导的血管生成信号传导的某些分子机制，其可能在成人组织中受损，部分原因是与年龄相关的TNFR 2 p75表达降低。此外，这一建议可能导致一个基因靶点的鉴定，可用于改善不良的恢复和预防严重缺血诱导的损害在成人冠状动脉和外周血管疾病的发展。

DESCRIPTION (provided by applicant): Background: Aging is a risk factor for development of coronary and peripheral artery diseases. The extent of ischemic damage and functional recovery in case of extensive impairment of vascularization is largely depending on the development of new collateral vessels. Tumor necrosis factor alpha (TNF-a), a macrophage/monocyte-derived pluripotent mediator and pro-inflammatory cytokine is expressed in ischemic areas and reported to induce angiogenesis. TNF has been reported to induce the expression of many angiogenesis related genes, through two different TNF receptors, TNFR1 (p55) and TNFR2 (p75). In various vascular ECs, TNF increased the expression of angiogenic factors VEGF, bFGF, IL-8, however, the role of two distinct TNF receptors in mediating these responses are still unclear. Hypothesis: p55 is largely known to mediate cytotoxic effects of TNF, whereas signaling through p75 is mostly implied in protective effects of TNF-alpha and because aging is associated with increased expression of p55 and decreased expression of p75 in cells from aged humans we hypothesized that the p75 may be essential in angiogenic signaling in adults. Purpose: 1) Determine the contribution of TNFR2 p75 on VEGF and bFGF gene expression on EC function in vitro and on angiogenesis in vivo; TNF-induced pro-angiogenic signaling and EC function is mediated, in large part, through p75 TNFR2. 2) Determine molecular mechanisms underlying TNF-mediated ischemia-induced survival and apoptosis signaling in ECs; In the absence of TNFR2 p75 post-ischemic apoptotic signaling is exaggerated. 3) Determine to what extent ischemia-induced mobilization, migration and recruitment of EPCs from bone marrow depends on signaling through p75 TNFR2; a) Ischemia-induced mobilization of EPCs from bone marrow is mediated, at least in part, via TNFR2 p75; b) Functional TNFR2 p75 is necessary for proper contribution of bone marrow-derived EPCs to post-ischemic recovery. Significance: the goal of this proposal is to define certain molecular mechanisms of iscmemia-induced TNF- mediated angiogenic signaling that may be impaired in adult tissue, in part, due to age-associated decrease in TNFR2 p75 expression. In addition, this proposal may lead to an identification of a gene target, which can be used to improve the poor recovery and prevent the development of severe ischemia-induced damage in adult coronary and peripheral vascular diseases.