Serotonin and the Rho Signaling Pathway in Smooth Muscle Cells

描述（申请人提供）：临床，动物实验和人类遗传信息目前支持血清素（5- HT）与肺动脉高压（PH）的关系。我们和其他人的研究表明，5-HT转运体（5- htt）和5-HT受体（5- htrs）在肺血管平滑肌细胞（SMC）对5-HT的增殖反应中都很重要。我们已经确定了5-HTT和5-HTRs通过独立刺激增殖反应中的信号通路的协同作用。MARK通过5-HTT被激活，通过5-HT 1B激活Rho通路参与了MARK从SMC细胞质到细胞核的转运。最近，我们还发现5-HT可激活PDGF受体(R)，而酪氨酸激酶抑制剂格列卫（Gleevec）对这种激活的干扰可阻断5-HT诱导的SMC增殖。Rho通路在5- ht诱导的SMC增殖中起核心作用，并被报道参与缺氧诱导的PH；重要的是，目前有药物可以修饰这一途径。我们假设Rho通路的激活和PDGFR的反激活参与了SMC的增殖和迁移过程，这在ph的发展中很重要。我们希望在本建议中更好地研究体外和体内协调SMC增殖和迁移的5- ht相关信号通路。为此，我们计划：1)进一步定义培养中SMCs中5- ht诱导的Rho信号的上游和下游效应物，这些效应物导致SMC增殖和迁移；2)确定他汀类药物及其他香叶基和法尼基转移酶抑制剂对5-HT诱导的SMC反应的影响及作用机制；3)评价5-HT反激活PDGFR在SMC增殖和迁移反应中的作用；4)利用野生型、5-HTT和5-HTR转基因小鼠暴露于缺氧并通过渗透泵注入5-HT，将体外发生的信号通路与体内发生的信号通路联系起来。我们相信整个实验将更好地了解5- ht相关的细胞信号通路，这可能在PH中起作用，并可能为这种疾病的治疗提供新的方法。

DESCRIPTION (provided by applicant): Clinical, animal experimental and human genetic information currently support a relationship of serotonin ( 5- HT) to pulmonary hypertension (PH). Studies by us and others have indicated the importance of both the 5- HT transporter (5-HTT) and 5-HT receptors (5-HTRs) in the pulmonary vascular smooth muscle cell (SMC) proliferative response to 5-HT. We have identified collaborative actions of the 5-HTT and 5-HTRs through independent stimulations of signaling pathways in the proliferative response. MARK is activated through the 5-HTT and activation of the Rho pathway via 5-HT 1B participates in translocation of MARK from SMC cytoplasm to nucleus. More recently, we have also found that 5-HT transactivates the PDGF receptor (R) and interference of this activation by Gleevec, a tyrosine kinase inhibitor, blocks 5-HT-induced SMC proliferation. The Rho pathway plays a central role in 5-HT-induced SMC proliferation and has been reported to participate in hypoxia-induced PH; importantly, agents are currently available to modify this pathway. We hypothesize that activation of the Rho pathway and transactivation of PDGFR participate in SMC proliferative and migratory processes important in development of PH. We wish in this proposal to better study the 5-HT-related signaling pathways in vitro and in vivo that orchestrate SMC proliferation and migration. To do this we plan to: 1) Further define upstream and downstream effectors of 5-HT-induced Rho signaling in SMCs in culture that lead to SMC proliferation and migration; 2) Determine the effect and mechanisms of action of statins and other geranylgeranyl and farnesyl transferase inhibitors on the 5-HT- induced SMC responses; 3) Evaluate the role of transactivation of PDGFR by 5-HT in SMC proliferative and migratory responses; and 4) Correlate the signaling pathways occurring in vitro with those operative in vivo with the use of wild type and 5-HTT and 5-HTR transgenic mice exposed to hypoxia and infused with 5-HT by osmotic pumps. We believe the overall experiments will provide a better appreciation of 5-HT-related cell signaling pathways that may be operative in PH and may allow new approaches to therapy of this disease.