Apoj/Clusterin:A Protective Protein In Vascular Biology

描述(由申请人提供)：血管再闭塞仍然是支架置入的一个重要并发症：30%-50%的受试者在血管手术后一年内发生血管再闭塞。支架内再狭窄主要是由于平滑肌细胞的新生内膜增生所致。因此，了解新生内膜增生的机制(S)和生化参与者将优化干预方案的设计，从而降低血管手术后再狭窄的风险。我们的初步结果表明，载脂蛋白(Apo)J/Clusterin可能是决定血管对损伤的反应和新生内膜病变发展的重要调节因子。以遗传学定义的小鼠为模型，我们的结果表明，载脂蛋白J的表达是对颈动脉机械损伤的反应。重要的是，与野生型小鼠相比，apoJ(-/-)小鼠在动脉损伤后2周出现了更严重的新生内膜病变。此外，更多的初步结果表明，与喂食同样富含胆固醇的致动脉粥样硬化饮食的apoJ野生型小鼠相比，apoJ(-/-)小鼠出现了更高的高胆固醇血症。这种高胆固醇血症与载脂蛋白E在脂蛋白颗粒中的分布改变有关。因此，本研究使用在体小鼠模型来验证这一假说，即载脂蛋白J在体内通过调节导致血管闭塞疾病的一个或多个主要事件而具有直接的血管保护功能。具体目标1包括三个部分。首先，比较了野生型和apoJ(-/-)小鼠从血管损伤时间到新生内膜形成时间的事件顺序。观察到血管病理差异的时间与野生型小鼠apoJ的时间表达有关。以这些数据为指导，第二部分进行基因表达谱研究，以确定载脂蛋白J在血管损伤反应中调节的生物和功能途径。第三部分利用apoJ-TG小鼠和腺病毒介导的apoJ基因直接转移到血管壁来验证增加apoJ表达是限制新生血管增生的可行策略的推论。特异性目的2验证apoJ缺乏通过改变脂蛋白之间的apoE分布来降低脂蛋白分解代谢从而加重饮食诱导的高胆固醇血症的假说。我们将研究apoJ野生型和apoJ(-/-)小鼠体内极低密度脂蛋白颗粒的代谢：定量分解代谢，定量脂蛋白合成和分泌，以及定量载脂蛋白E从高密度脂蛋白到极低密度脂蛋白的转换。在特定的目标3中，野生型apoJ(-/-)和apoJ-TG小鼠被喂养高胆固醇致动脉粥样硬化的食物，以验证apoJ具有保护作用的假说，也可以对抗进行性动脉粥样硬化。综上所述，这些研究将确定载脂蛋白J的新功能，并有助于我们更好地理解血管损伤反应中的致病事件。

DESCRIPTION (provided by applicant): Vascular reocclusion remains a significant complication of stent placement: vascular reocclusion occurs in 30-50% of subjects within 1 year of vascular surgery. In-stent restenosis is due primarily to neointima hyperplasia of smooth muscle cells. Thus, understanding the mechanism(s) and biochemical participants in neointima hyperplasia will optimize the design of intervention protocols that reduce the risk of restenosis after vascular surgery. Our Preliminary Results suggest that apolipoprotein (apo) J / clusterin may be an important regulator in determining the vascular response to injury and the development of the neointima lesion. With genetically defined mice as the model, our results show that apoJ expression is induced in response to mechanical injury of the carotid artery. Importantly, apoJ(-/-) mice developed a more severe neointima lesion 2 wk after arterial injury in comparison to wild type mice. Moreover, additional Preliminary Results demonstrate that apoJ(-/-) mice develop increased hypercholesterolemia compared to apoJ wild type mice fed the same cholesterol enriched atherogenic diet. This hypercholesterolemia is associated with an altered distribution of apoE among lipoprotein particles. Therefore, the current study uses the in vivo mouse model to test the hypothesis that apoJ has a direct vascular protective function in vivo by modulating one or more of the cardinal events that contribute to vascular occlusive disease. Specific Aim 1 contains three parts. First, the sequence of events from the time of vascular injury to the time of neointima formation in wild type and apoJ(-/-) mice is compared. The time when differences in vascular pathology are observed is correlated with the temporal expression of apoJ in wild type mice. With these data as a guide, the second part performs gene expression profiling studies to determine the biologic and functional pathways that are modulated by apoJ in the vascular response to injury. The third part uses apoJ-tg mice and adenovirus mediated apoJ gene transfer directly to the vessel wall to test the corollary hypothesis that increased apoJ expression is a viable tactic to limit neointirna hyperplasia. Specific Aim 2 tests the hypothesis that apoJ deficiency exacerbates diet induced hypercholesterolemia by decreasing lipoprotein catabolism via alteration of apoE distribution among lipoproteins. We will characterize the metabolism of VLDL particles in apoJ wild type and apoJ(-/-) mice: quantify catabolism, quantify lipoprotein synthesis and secretion, and quantify transter of apoE from HDL to VLDL. In Specific Aim 3 wild type, apoJ(-/-), and apoJ-tg mice are fed a cholesterol enriched atherogenic diet to test the hypothesis that apoJ is protective, also, against progressive atherosclerosis. Taken together, these studies will identify novel functions of apoJ as well as contribute to our better understanding of the pathogenic events in the vascular response to injury.