Early Growth Response-1 (Egr-1), PKC Beta and Restenosis

描述(申请人提供)：再狭窄，或复发性管腔狭窄，是一个重要的临床问题，尤其是在糖尿病患者。随着西罗莫司涂层支架的出现，血管成形术后再狭窄的风险已显著降低。最近的研究表明，联合治疗具有潜在的强大影响，例如与糖蛋白IIb/IIIa抑制剂联合治疗。因此，充分剖析血管成形术后异常新生内膜扩张的分子机制是至关重要的，因为识别新的和有效的辅助治疗将加速有效的治疗干预策略，特别是在糖尿病患者。我们的实验室一直专注于即刻早期基因早期生长反应-1(EGR-1)及其关键上游调节因子PKCb在急性动脉损伤反应中的作用。最近的观察强调了这样一个概念，即EGR-1的上调与慢性血管/炎症应激有关，因为与邻近的非动脉粥样硬化斑块相比，在啮齿动物的动脉损伤后，人和小鼠动脉粥样硬化病变中EGR-1的转录显著上调。在野生型C57BL/6小鼠急性剥脱伤后的血管壁中，EGR-1迅速表达，尤其是在血管内皮细胞(EC)和平滑肌细胞(SMC)中；在高胆固醇血症载脂蛋白E(Apo E)缺失(0)小鼠中，EGR-1也在急性损伤血管中的单核巨噬细胞(MP)中表达上调。我们的研究支持EGR-1及其上游调节因子PKCBetaII在动脉损伤后与新生内膜扩张相关的过程中的作用；EGR-1或PKCbeta基因缺陷的小鼠在股动脉剥脱损伤后表现出显著的抑制新生内膜扩张的作用。这些考虑使我们假设，急性动脉损伤导致PKCbetaII的快速激活，从而推动EGR-1的上调；与EC、SMC和MP激活以及调节新生内膜扩张密切相关的机制。我们建议剖析PKCbetaII/EGR-1轴在体内促进再狭窄的机制。为了检验这些概念，我们将在启动子的控制下产生并鉴定表达功能缺陷(显性阴性，DN PKCbetaII)的转基因小鼠，以将其定向表达于EC、SMC和MP。急性裸露动脉损伤对正常血糖和糖尿病小鼠以及仔鼠对照的影响将被研究。如果成功，这些研究将阐明PKCbeta/EGR-1轴调节动脉损伤反应的确切细胞特异性和信号通路，并确定这些通路是否为动脉损伤治疗干预的合理靶点。

DESCRIPTION (provided by applicant): Restenosis, or recurrent lumenal narrowing, is a significant clinical problem that is especially enhanced in diabetes. With the advent of sirolimus-coated stents, the risk of restenosis after angioplasty has been strikingly reduced. Recent studies suggest the potentially powerful impact of combination therapy, such as with glycoprotein IIb/IIIa inhibitors. Therefore, it is critical to fully dissect the molecular mechanisms underlying aberrant neointimal expansion after angioplasty, as identification of new and powerful adjunctive therapies will accelerate effective therapeutic intervention strategies, particularly in diabetic subjects. Our laboratory has focused on the role of the immediate early gene, early growth response-1 (egr-1) and its key upstream regulator, PKCb, in the response to acute arterial injury. Recent observations underscored the concept that upregulation of egr-1 is linked to chronic vascular/inflammatory stress, as transcripts for egr-1 are strikingly upregulated in human and murine atherosclerotic lesions compared to adjacent non-atheromatous plaque, and after denuding arterial injury in rodents. In the vessel wall subjected to acute denuding injury in wild-type C57BL/6 mice, egr-1 is expressed rapidly after injury, particularly in smooth muscle cells (SMC) and endothelial cells (EC); in hypercholesterolemic apolipoprotein E (apo E) null (0) mice, egr-1 is also upregulated in mononuclear phagocytes (MP) infiltrating the acutely injured vessel. Our studies support a role for egr-1 and its upstream regulator, PKCBetaII in processes linked to neointimal expansion after arterial injury; mice genetically deficient in egr-1 or PKCbeta display significantly decreased neointimal expansion after femoral artery denudation injury. These considerations lead us to hypothesize that acute arterial injury results in rapid activation of PKCbetaII, thereby driving upregulation of egr-1; mechanisms linked importantly to EC, SMC, and MP activation, and modulation of neointimal expansion. We propose to dissect the mechanisms by which the PKCbetaII/egr-1 axis contributes to restenosis in vivo. To test these concepts, we will generate and characterize transgenic mice expressing functionally deficient (dominant negative, DN PKCbetaII) under the control of promoters to direct expression to EC, SMC and MP. The impact of acute denuding arterial injury in euglycemic and diabetic mice, and littermate controls will be studied. If successful, these studies will elucidate the precise cell-specific and signaling pathways by which the PKCbeta/egr-1 axis modulates the response to arterial injury and identify if these pathways are logical targets for therapeutic intervention in arterial injury.