Role of PTEN in Vascular Lesion Formation

描述（由申请方提供）：再狭窄的特征是平滑肌细胞（SMC）通过中膜来源SMC的去分化、迁移和增殖在动脉内膜中蓄积。以骨髓源性和/或循环炎性和祖细胞募集至受损血管为特征的炎性反应也有助于再狭窄。几种趋化因子，包括MCP-1/JE、SDF-1a、IL-6和CXCL 1/KC，在损伤后在SMC中被快速诱导，并通过募集炎性和血管祖细胞参与重塑过程。这些因素中的一些也已被证明直接影响SMC本身的生物学功能，将SMC作为损伤反应的介质和效应器。然而，在SMC中激活的响应于损伤的潜在分子程序尚未明确定义。我们以前的工作表明SMC特异性的PTEN失活，PI 3-激酶信号的负调节剂，是驱动血管病变形成的早期触发因素。我们产生了诱导型SMC特异性PTEN突变小鼠（PTEN iKO），并发现与对照相比，PTEN iKO小鼠在颈动脉损伤后主要血管中表现出总PTEN的显著减少，伴随着磷酸化Akt水平的增加和新生内膜形成的增强。PTEN缺陷的SMC在体外表现出自分泌生长表型在基础条件下，并表达细胞因子/趋化因子谱类似于在SMC中观察到的实验损伤。初步数据显示，PTEN耗竭激活转录因子NF？B和HIF-1 a; B或HIF-1 a阻断了由PTEN缺失介导的特异性趋化因子的上调。另一方面，我们的初步数据表明，核受体PPAR？的激活，在SMC上调PTEN，因此我们的研究将检查的能力？激活以抑制SMC增殖并通过SMC PTEN的上调调节抗炎反应。总体而言，我们的初步数据提供的证据表明，SMC PTEN信号的改变作为一个关键的启动决定因素，通过产生一个家族的趋化因子，通过旁分泌机制招募炎症/祖细胞，促进自分泌SMC增生反应，驱动病理性血管重塑。因此，预计SMC PTEN信号传导的恢复将逆转由血管损伤引起的级联事件。我们将确定在培养的无PTEN SMC中，PTEN缺失对SMC产生祖细胞/炎性细胞介质的作用的后果和机制，并评估SMC特异性缺失PTEN在小鼠中对趋化因子诱导的SMC增生和目的一中实验性血管损伤后新生内膜形成期间祖细胞和炎性细胞的募集的相对贡献。在目标二中，我们将确定PPAR的作用？激动剂对PTEN的上调和SMC的生物学功能的影响，并确定PTEN调节在介导PPAR？抗损伤诱导的血管重塑发展的激动剂。 公共卫生相关性：心脏病并发症仍然是西方社会的主要死亡原因。虽然血管成形术/支架部署和移植物移植已被广泛用于治疗动脉粥样硬化，但这些手术中的很大一部分由于术后再狭窄而失败，其特征在于导致血管阻塞的显著细胞生长和炎症反应。因此，大量的努力已经进入定义调节这些过程的潜在机制，以减少介入后血管闭塞。我们的研究旨在测试血管细胞表达的蛋白质PTEN在积极阻断趋化因子家族表达中的作用和作用机制，所述趋化因子家族在血管干预后促进血管细胞生长和炎症反应。

DESCRIPTION (provided by applicant): Restenosis is characterized by smooth muscle cell (SMC) accumulation in the arterial intima through dedifferentiation, migration, and proliferation of medial-derived SMC. An inflammatory response, characterized by bone marrow-derived and/or circulating inflammatory and progenitor cell recruitment to the injured vessel, also contributes to restenosis. Several chemokines, including MCP-1/JE, SDF-1a, IL-6, and CXCL1/KC, are rapidly induced in SMC following injury and participate in the remodeling process through the recruitment of inflammatory and vascular progenitor cells. Some of these factors have also been shown to directly affect the biological function of the SMC itself placing the SMC as both a mediator and an effector of the injury response. However, the underlying molecular programs activated in SMC in response to injury are not clearly defined. Our previous work indicates SMC-specific PTEN inactivation, a negative regulator of PI3-kinase signaling, is an early trigger driving vascular lesion formation. We generated inducible SMC-specific PTEN mutant mice (PTEN iKO) and found that, compared to controls, PTEN iKO mice exhibit significant reductions of total PTEN in major vessels with accompanying increased phosphoAkt levels and enhanced neointima formation following carotid arterial injury. PTEN-deficient SMC in vitro exhibit an autocrine growth phenotype under basal conditions and express a cytokine/chemokine profile similar to what is observed in SMC following experimental injury. Preliminary data show that PTEN depletion activates the transcription factors, NF?B and HIF-1a; inhibition of NF?B or HIF-1a blocked the upregulation of specific chemokines mediated by PTEN depletion. On the other hand, our preliminary data suggest that activation of the nuclear receptor, PPAR?, in SMC upregulates PTEN, therefore our studies will examine the ability of PPAR? activation to inhibit SMC proliferation and regulate anti-inflammatory responses through the upregulation of SMC PTEN. Overall, our preliminary data provide evidence that an alteration in SMC PTEN signaling serves as a key initiating determinant driving pathological vascular remodeling through the production of a family of chemoattractants that recruit inflammatory/progenitor cells through a paracrine mechanism and promote an autocrine SMC hyperplastic response. Therefore, restoration of SMC PTEN signaling is anticipated to reverse the cascade of events brought on by vascular injury. We will determine the consequences and mechanism of action of PTEN loss on SMC production of progenitor/inflammatory cell mediators in cultured PTEN null SMC and assess the relative contribution of SMC-specific deletion of PTEN in mice on chemokine-induced SMC hyperplasia and recruitment of progenitor and inflammatory cells during neointima formation following experimental vascular injury in Aim One. In Aim Two, we will determine the role of PPAR? agonists on the upregulation of PTEN and biological functions of SMC and determine the role of PTEN regulation in mediating the protective effects of PPAR? agonists against the development of injury-induced vascular remodeling. PUBLIC HEALTH RELEVANCE: Complications of heart disease remain the leading cause of death in Western societies. While angioplasty/stent deployment and graft transplantations have been widely used for the treatment of atherosclerosis, a significant proportion of these procedures fail due to post-procedure restenosis, characterized by significant cell growth and inflammatory responses that lead to vessel blockage. Therefore, a great deal of effort has gone into defining the underlying mechanisms regulating these processes to reduce post-intervention vascular occlusion. Our studies are designed to test the role and mechanisms of action of a protein, PTEN, expressed by vascular cells in actively blocking the expression of a family of chemokines that otherwise promote vascular cell growth and an inflammatory response following vascular interventions.