Novel Targets of Rapamycin & Akt in VSMC Differentiation

描述（由申请人提供）：血管平滑肌细胞表型的调控仍然是血管平滑肌细胞（VSMC）生物学中一个悬而未决的关键问题。VSMC保留了一个显著的可塑性去分化和重新进入细胞周期允许生长和愈合。然而，这种可塑性也可能导致严重的血管病变，包括再狭窄、移植物衰竭、动脉粥样硬化和移植血管病变。值得注意的是，尽管有大量的研究，调节可塑性的过程在很大程度上是未知的，很少有治疗方法成功地针对这一过程。随着血管疾病患者数量的不断增加，迫切需要发现新的靶点。虽然雷帕霉素类似物是有效的药物洗脱支架剂，但支架晚期血栓形成的风险和随后需要长期抗血小板治疗仍然使其使用复杂化。我们之前的研究表明，mTORC1抑制剂雷帕霉素促进VSMC分化，揭示了细胞类型特异性转录是mTORC1途径的一种新功能。此外，我们暗示Akt2的反馈激活对于雷帕霉素诱导的分化至关重要。我们已经发现了Akt1和Akt2在血管损伤反应中的不同作用。我们还发现TET2和LMO7是mtorc1调节VSMC表型的新蛋白。基于这些令人兴奋的初步结果，我们将解决mTORC1途径通过表观遗传（TET2）和转录（LMO7）调控VSMC表型和损伤反应的总体假设，以及Akt亚型在再狭窄病理和雷帕霉素治疗反应中发挥不同作用。在特异性目标1中，我们将确定TET2在VSMC表型调节中的作用以及雷帕霉素如何调节它。在特异性目标2中，我们将确定LMO7在体外雷帕霉素诱导的VSMC分化和体内损伤反应中的作用。在具体目标3中，我们将确定Akt1和

DESCRIPTION (provided by applicant): Regulation of VSMC phenotype remains a key unanswered question in vascular smooth muscle cell (VSMC) biology. VSMC retain a remarkable plasticity to de-differentiate and re-enter the cell cycle allowing for growth and healing. However, such plasticity can also contribute to severe vascular pathologies, including restenosis, graft failure, atherosclerosis, and transplant vasculopathy. Remarkably, despite intense study, the process regulating plasticity is largely unknown with few therapies successfully targeting this process. With the growing numbers of patients suffering from vascular disease the discovery of novel targets is urgently warranted. While rapamycin analogs are efficacious drug-eluting stent agents, the risk of late-stent thrombosis and subsequent need for long term antiplatelet therapy still complicates their use. Our previous studies have revealed that the mTORC1 inhibitor, rapamycin, promotes VSMC differentiation, revealing cell type-specific transcription as a novel function of the mTORC1 pathway. Moreover, we implicated feedback activation of Akt2 as critical for rapamycin-induced differentiation. We have discovered distinct roles for Akt1 and Akt2 in the response to vascular injury. We have also identified TET2 and LMO7 as novel mTORC1-regulated proteins that modulate VSMC phenotype. Based upon these exciting Preliminary Results we will address the overall hypothesis that the mTORC1 pathway governs VSMC phenotype and response to injury through epigenetic (TET2) and transcriptional (LMO7) regulation, and that Akt isoforms play distinct roles in the pathology of restenosis and therapeutic response to rapamycin. In Specific Aim 1, we will determine the role of TET2 in VSMC phenotypic modulation and how it is regulated by rapamycin. In Specific Aim 2, we will determine the role of LMO7 in rapamycin- induced VSMC differentiation in vitro and in response to injury in vivo. In Specific Aim 3, we will determine the differential roles of Akt1 and Akt2 in injury response in vascular tissues. If our goals are achieved, we will have identified key regulatory elements in VSMC plasticity. Understanding the critical mechanisms by which mTORC1 regulates VSMC phenotype will lead to improved cardiovascular therapeutics.