AIBP-Mediated Cholesterol Efflux and Angiogenesis

描述（由申请人提供）：心肌梗死是美国死亡率和发病率的主要原因。再灌注后，血管生成和微循环的恢复是恢复正常心脏功能的关键组成部分。血管生成对斑马鱼心脏再生也很重要。对血管生成的分子机制的理解已经取得了很大进展，但代谢和血管生成之间的联系研究较少。我的初步研究强烈表明，胆固醇从内皮细胞流出调节血管生成。我发现体外和胚胎斑马鱼中的血管生成受ApoA-I结合蛋白（AIBP）的调节，AIBP是一种分泌蛋白，在与ApoA-I物理相关的蛋白质筛选中鉴定。AIBP促进ABCG 1介导的内皮细胞胆固醇流出。此外，AIBP控制胚胎斑马鱼节段动脉（SeA）的形成。AIBP的过表达抑制SeA发芽，而AIBP的敲除导致SeA发芽和分支失调。在我指导的K99阶段，我建议测试的假设，分泌AIBP功能作为一个特定位点的调节胆固醇流出EC和管理胚胎血管生成。首先，我计划证明AIBP介导的ABC转运蛋白依赖的胆固醇流出调节斑马鱼胚胎血管生成。我发现AIBP缺失引起的表型是通过敲低细胞胆固醇转运蛋白ABCA 1和ABCG 1而表型复制的。本研究的目的是证明AIBP对胚胎血管生成的影响依赖于AIBP在胆固醇代谢中的作用。这些研究将建立一个以前未被认识的机制连接胆固醇流出与胚胎血管生成。然后在我的独立R00阶段，我将证明AIBP在成年斑马鱼中的过度表达减弱了心脏再生。冠状动脉血管的形成被认为对于心脏再生是重要的，因为它可以想象地提供心肌细胞的稳健增殖所必需的资源。我将建立AIBP条件表达转基因鱼系，并研究AIBP过表达对斑马鱼心脏再生过程中血管生成的影响。我在独立R00阶段的第二个目标是评估AIBP表达调节小鼠冠状动脉血管生成。因为我的研究结果表明AIBP限制血管生成，我认为心肌细胞特异性AIBP的丢失将促进心脏肥大条件下的血管生成。这些研究将阐明AIBP控制的血管生成在心脏再生和心脏肥大中的潜在作用，并提出可能的治疗干预措施，通过促进血管生成来刺激微血管的恢复。

DESCRIPTION (provided by applicant): Myocardial infarction is the leading cause of mortality and morbidity in the US. Following reperfusion, angiogenesis and restoration of microcirculation is a critical component in the recovery of normal cardiac function. Angiogenesis is also important for zebrafish heart regeneration. Much progress has been made towards understanding of the molecular mechanisms of angiogenesis, but the connection between metabolism and angiogenesis is less studied. My preliminary studies strongly suggest that cholesterol efflux from endothelial cells regulates angiogenesis. I found that angiogenesis in vitro and in embryonic zebrafish was regulated by ApoA-I binding protein (AIBP), a secreted protein identified in a screen of proteins that physically associate with ApoA-I. AIBP accelerated ABCG1-mediated cholesterol efflux from endothelial cells (EC) in vitro. Furthermore, AIBP controlled formation of segmental arteries (SeA) in embryonic zebrafish. Overexpression of AIBP inhibited SeA sprouting, while AIBP knockdown resulted in dysregulated SeA sprouting and branching. In my mentored K99 phase, I propose to test the hypothesis that secreted AIBP functions as a site-specific regulator of cholesterol efflux from EC and governs embryonic angiogenesis. First, I plan to demonstrate that AIBP-mediated, ABC transporters-dependent cholesterol efflux regulates embryonic angiogenesis in zebrafish. I found that the phenotype caused by the loss of AIBP was phenocopied by knockdown of cellular cholesterol transporters ABCA1 and ABCG1. My goal in this Aim is to prove that the effect of AIBP on embryonic angiogenesis relies on the AIBP function in cholesterol metabolism. These studies will establish a previously unrecognized mechanism connecting cholesterol efflux with embryonic angiogenesis. Then in my independent R00 phase, I will demonstrate that AIBP overexpression in adult zebrafish attenuates heart regeneration. Formation of coronary vasculature is believed to be important for heart regeneration because it conceivably provides resources necessary for robust proliferation of cardiomyocytes. I will make an AIBP conditional expression transgenic fish line, and investigate the impact of AIBP overexpression on angiogenesis that occurs during zebrafish heart regeneration. My second Aim in the independent R00 phase is to assess that AIBP expression modulates coronary angiogenesis in mice. Because my results suggest that AIBP limits angiogenesis, I propose that cardiomyocyte-specific loss of AIBP would promote angiogenesis under conditions of cardiac hypertrophy. These studies will elucidate a potential role for AIBP-governed angiogenesis in heart regeneration and in cardiac hypertrophy and suggest possible therapeutic interventions to stimulate the recovery of the microvasculature by promoting angiogenesis.