Molecular pathology of vascular injury

描述（申请人提供）：HL 54131的中心主题是研究血管疾病中的重要基因。在上一个资助周期进行的工作集中在生存素作为血管生成内皮细胞凋亡和有丝分裂调节因子的多功能抑制剂。从这些实验中出现了三个新的范例，构成了本延续申请的基础。首先，存活素被确定为平滑肌细胞中PDGF依赖性存活的介导物，并且对存活素途径的分子干扰在体内防止急性动脉损伤后的病理性血管重塑。第二，存活素抑制凋亡的机制与线粒体细胞死亡的上游启动有关，并且存活素的离散池被示出定位于线粒体。第三，生存素被表征为由Wnt/TCF/β-连环蛋白诱导的新型细胞保护因子，其是一种保留组织干细胞和骨髓祖细胞的多能性的基因模式化途径。因此，一个统一的假设，即生存素维持血管损伤过程中的平滑肌细胞及其祖细胞的稳态，可以制定，并将在本继续申请进行研究。在第一个具体目标中，实验将绘制平滑肌细胞中PDGF诱导生存素的结构和信号传导要求。这是一种生长因子特异性途径，将从Wnt/TCF/β-连环蛋白基因表达、细胞周期蛋白依赖性激酶抑制剂的调节、ERK信号传导、PI 3激酶/Akt的激活和STAT磷酸化方面进行表征。第二个具体目标将剖析线粒体存活素在细胞凋亡抑制中的作用，解决线粒体运输、渗透性转换、线粒体组装和增强的IAP依赖性细胞保护的机制。第三个具体目标将确定生存素在骨髓和平滑肌祖细胞的细胞活力、增殖和集落形成中的重要性。该途径在急性动脉损伤后病理性血管重塑中的影响将在骨髓移植实验中使用祖细胞中存活素表达/功能的转基因或逆转录病毒操作来确定。总的来说，实验计划旨在阐明急性血管损伤期间平滑肌细胞稳态的一种新的生存途径。

DESCRIPTION (provided by applicant): The central theme of HL54131 is to study genes of importance in vascular diseases. Work carried out during the previous grant cycle focused on survivin as a hi-functional inhibitor of apoptosis and mitotic regulator in angiogenic endothelium. Three new paradigms emerged from these experiments that constitute the foundation of the present continuation application. First, survivin was identified as a mediator of PDGF-dependent survival in smooth muscle cells, and molecular interference with the survivin pathway prevented pathologic vascular remodeling after acute arterial injury, in vivo. Second, the mechanism of apoptosis inhibition by survivin was linked to the upstream initiation of mitochondrial cell death, and a discrete pool ot survivin was shown to localize to mitochondria. Third, survivin was characterized as a novel cytoprotective factor induced by Wnt/TCF/beta-catenin, a gene patterning pathway that preserves the pluripotency of tissue stem cells and bone marrow progenitors. Therefore, a unifying hypothesis that survivin maintains the homeostasis of smooth muscle cells and their progenitors during vascular injury can be formulated, and will be investigated in the present continuation application. In the first specific aim, experiments will map the structural and signaling requirements of PDGF induction of survivin in smooth muscle cells. This is a growth factor-specific pathway and will be characterized with respect to Wnt/TCF/beta-catenin gene expression, modulation of cyclin-dependent kinase inhibitors, ERK signaling, activation of PI3 kinase/Akt, and STAT phosphorylation. The second specific aim will dissect the role of mitochondrial survivin in apoptosis inhibition, addressing mechanisms of mitochondrial trafficking, permeability transition, apoptosome assembly, and enhanced lAP-dependent cytoprotection. The third specific aim will determine the importance of survivin in cell viability, proliferation, and colony formation of bone marrow and smooth muscle cell progenitors. The impact of this pathway in pathologic vascular remodeling after acute arterial injury will be determined in bone marrow transplantation experiments using transgenic or retroviral manipulation of survivin expression/function in progenitor cells. Overall, the experimental plan is designed to elucidate a novel survival pathway central to smooth muscle cell homeostasis during acute vascular injury.