Mechanotransduction in bladder smooth muscle

描述（由申请人提供）：项目摘要泌尿道中的纤维增生性重塑与许多病理学相关，包括继发于出口梗阻的肥大性膀胱生长、神经源性膀胱和糖尿病。虽然暴露于病理刺激的膀胱壁中发生的宏观变化，例如壁增厚和肌肉收缩性丧失，多年来一直受到重视，但在分子水平上构成组织重塑基础的信号仍然知之甚少。本研究的目的是揭示调节膀胱平滑肌对病理刺激的生长和分化的信号事件。这些过程的关键调节因子的鉴定将揭示治疗干预的新靶点。由于膀胱是唯一的中空器官作为一个特权网站的药物输送，这些研究可能会直接导致新的治疗尿路功能障碍的机会，特别是在肥大的背景下。来自我们小组的数据表明，磷酸肌醇-3-激酶（PI 3 K）/Akt通路作为初级膀胱平滑肌细胞（BSMC）响应于机械刺激或血小板衍生生长因子（PDGF）处理的生长的介导物。SMC暴露于拉伸或PDGF在体外或膨胀的完整的啮齿动物膀胱离体引起强大的磷酸化的丝氨酸-苏氨酸激酶Akt，PI 3 K的主要效应。原代人BSMC的表达谱显示拉伸是基因表达的高度选择性调节剂，其中<0.2%的表达基因组被鉴定为机械响应。计算机模拟分析表明AP-1家族成员是牵张诱导的BSMC基因表达的潜在调节因子。虽然Akt和AP-1被机械刺激上调，但它们相互作用以调节中空器官重塑的程度基本上完全未被研究。在这个建议中，我们将测试的假设，Akt-和AP-1调节信号介导的膀胱平滑肌的增长，在响应机械刺激和收敛在一个或多个水平内的细胞。我们将使用BSMC拉伸的体外模型以及膀胱扩张的动物模型来解决以下具体目标：（1）确定Akt如何调节体外和体内暴露于机械刺激的SMC的生长;（2）确定AP-1介导的基因表达变化如何调节SMC生长以及Akt的调节程度。我们将使用几种互补的方法在体外和体内调节BSMC中Akt和AP-1依赖的信号传导，包括RNA干扰，药理学抑制和蛋白转导技术。我们预计，从这些实验的结果将提供新的见解病理膀胱平滑肌growth.Project叙述膀胱疾病的有效治疗机制的基础上缺乏了解的分子信号，调节组织生长在正常和病理的情况下，阻碍。拟议的实验将研究两个蛋白质家族Akt和AP-1如何相互作用以调节膀胱平滑肌响应机械刺激的生长。我们预计这项分析将揭示膀胱肌肉生理学的基本机制，也可能提供新的治疗策略的见解。

DESCRIPTION (provided by applicant): Project Abstract Fibroproliferative remodeling in the urinary tract is associated with a number of pathologies including hypertrophic bladder growth secondary to outlet obstruction, neurogenic bladder and diabetes. Although the macroscopic changes that occur in the bladder wall exposed to pathologic stimulation, such as wall thickening and loss of muscle contractility, have been appreciated for many years, the signals that underlie tissue remodeling at the molecular level are still poorly understood. The goal of the proposed studies is to uncover the signaling events that regulate growth and differentiation of bladder smooth muscle in response to pathologic stimuli. The identification of key regulators of these processes will reveal novel targets for therapeutic intervention. Because the bladder is unique among hollow organs as a privileged site for drug delivery, these studies may lead directly to opportunities for novel therapies for urinary tract dysfunction particularly in the context of hypertrophy. Data from our group have implicated the phosphoinositide-3-kinase (PI3K)/Akt pathway as a mediator of primary bladder smooth muscle cell (BSMC) growth in response to mechanical stimulation or platelet- derived growth factor (PDGF) treatment. Exposure of SMC to stretch or PDGF in vitro or distension of the intact rodent bladder ex vivo elicited robust phosphorylation of the serine-threonine kinase Akt, a principal effector of PI3K. Expression profiling of primary human BSMC revealed stretch to be a highly selective regulator of gene expression, with <0.2% of the expressed genome identified as mechanically responsive. In silico analysis implicated AP-1 family members as potential regulators of stretch-induced BSMC gene expression. Although Akt and AP-1 are upregulated by mechanical stimuli, the extent to which they interact to regulate hollow organ remodeling is essentially completely unstudied. In this proposal we will test the hypothesis that Akt- and AP-1-regulated signals mediate growth of bladder smooth muscle in response to mechanical stimulation and converge at one or more levels within the cell. We will use an in vitro model of BSMC stretch as well as an animal model of bladder distension to address the following specific aims: (1) Determine how Akt regulates growth in SMC exposed to mechanical stimuli in vitro and in vivo; (2) Determine how AP-1-mediated changes in gene expression regulate SMC growth and the extent of regulation by Akt. We will use several complementary approaches to modulate Akt- and AP-1-dependent signaling in BSMC in vitro and in vivo, including RNA interference, pharmacologic inhibition and protein transduction technology. We anticipate that findings from these experiments will provide novel insights into the mechanisms underlying pathologic bladder smooth muscle growth.Project Narrative Effective treatment of bladder diseases is hampered by a lack of understanding about the molecular signals that regulate tissue growth both in normal and pathologic situations. The proposed experiments will investigate how two protein families, Akt and AP-1, interact to regulate the growth of bladder smooth muscle in response to mechanical stimulation. We anticipate this analysis will shed new light on fundamental mechanisms underlying bladder muscle physiology and may also provide insight into new treatment strategies.