Akt-Regulated Gene Expression in Bladder Smooth Muscle

描述(申请人提供)：本项目的目的是确定暴露在肥大信号下的膀胱平滑肌细胞(SMC)中的Akt靶基因。下尿路梗阻引起的膀胱肌肥大是儿童和成人的严重健康问题。膀胱肥大的机制在分子水平上几乎完全不清楚。然而，某些表型变化，如肌肉细胞肥大和增殖，重新激活胎儿基因表达程序和激活特定的信号转导级联，至少表面上类似于心肌肥厚的变化。这表明，类似的信号机制可能在肥大刺激下的心脏和膀胱中发挥作用。信令 通过磷脂酰肌醇-3-激酶(PI3K)/Akt通路参与心肌和骨骼肌肥大。我们最近证实，在机械拉伸和血小板衍生生长因子-BB(PDGF-BB)刺激下，膀胱SMC中Akt丝氨酸-苏氨酸激酶被激活，这两种刺激促进了膀胱SMC的生长。在这项提议中，我们将检验Akt是膀胱平滑肌肥大信号的中介物这一假设。具体目标为(1)：确定Akt激活对人膀胱SMC生长是否必要和充分。我们将使用激活的和显性-负性Akt结构来修饰膀胱SMC中的Akt活性，从而确定在膀胱肌肉生长中对Akt的需求。目的(2)：确定膀胱SMC对肥大刺激的Akt调控靶点。我们将通过对拉伸暴露的人膀胱SMC进行大规模的mRNA表达分析来确定Akt靶点，然后在适当的模型系统中验证它们。 在为期两年的项目期结束时，我们将确定Akt是否对膀胱肌生长是必需的，并将知道可能介导膀胱肌肉对肥大信号的反应的拉伸响应Akt重排基因的身份。从这些研究中获得的信息将支持和指导未来的研究，这些研究将定向于阐明Akt调节基因在膀胱肌中的作用机制。

DESCRIPTION (provided by applicant): The aim of this project is to identify Akt target genes in bladder smooth muscle cells (SMC) exposed to hypertrophic signals. The hypertrophic bladder muscle growth that occurs in response to lower urinary tract obstruction represents a serious health problem in both children and adults. The mechanisms that underlie bladder hypertrophy are almost completely undefined at the molecular level. However, certain phenotypic changes, such as muscle cell hypertrophy and hyperplasia, reactivation of a fetal gene expression program and activation of specific signal transduction cascades are similar, at least superficially, to changes that occur in cardiac hypertrophy. This suggests that similar signaling mechanisms may operate in the heart and bladder exposed to hypertrophic stimuli. Signaling through the phosphoinositide-3-kinase (PI3K)/Akt pathway has been implicated in cardiac and skeletal muscle hypertrophy. We have recently demonstrated activation of the Akt serine-threonine kinase in bladder SMC exposed to mechanical stretch and platelet-derived growth factor-BB (PDGF-BB), stimuli that promote bladder SMC growth. In this proposal we will test the hypothesis that Akt is a mediator of hypertrophic signals in bladder smooth muscle. The Specific Aims are Aim (1): determine whether Akt activation is necessary and sufficient for growth of human bladder SMC. We will modify Akt activity in bladder SMC using activated and dominant-negative Akt constructs and thereby establish the requirement for Akt in bladder muscle growth. Aim (2): identify Akt-regulated targets in bladder SMC in response to hypertrophic stimuli. We will identify Akt targets by large-scale mRNA expression analysis of human bladder SMC exposed to stretch, and then validate them in appropriate model systems. At the end of the 2-year project period we will have determined whether Akt is necessary for bladder muscle growth and will also know the identity of the stretch-responsive Akt-regutated genes that potentially mediate the response of bladder muscle to hypertrophic signals. The information obtained from these studies will underpin and inform future studies that will be directed towards elucidation of the mechanism of action of Akt-regulated genes in bladder muscle.