Akt-Regulated Gene Expression in Bladder Smooth Muscle

描述（由申请人提供）：本项目的目的是鉴定暴露于肥大信号的膀胱平滑肌细胞（SMC）中的Akt靶基因。下尿路梗阻引起的肥大性膀胱肌生长是儿童和成人的一个严重健康问题。膀胱肥大的潜在机制在分子水平上几乎完全不确定。然而，某些表型变化，如肌细胞肥大和增生，胎儿基因表达程序的重新激活和特定信号转导级联的激活，至少在表面上类似于心脏肥大中发生的变化。这表明，类似的信号机制可能在心脏和膀胱暴露于肥大刺激。信令 通过磷脂酰肌醇-3-激酶（PI 3 K）/Akt途径，已经涉及心脏和骨骼肌肥大。我们最近已经证明了Akt丝氨酸-苏氨酸激酶在膀胱平滑肌细胞暴露于机械拉伸和血小板衍生生长因子-BB（PDGF-BB），刺激，促进膀胱平滑肌细胞生长的激活。在这个提议中，我们将测试Akt是膀胱平滑肌肥大信号的介导者的假设。具体目的是目的（1）：确定Akt活化是否是人膀胱SMC生长所必需和充分的。我们将使用激活的和显性阴性Akt构建体来修饰膀胱SMC中的Akt活性，从而建立膀胱肌肉生长对Akt的需求。目的（2）：研究肥大刺激下膀胱平滑肌细胞Akt调控的靶点。我们将通过大规模的人膀胱平滑肌细胞暴露于拉伸的mRNA表达分析来识别Akt靶点，然后在适当的模型系统中验证它们。 在2年项目期结束时，我们将确定Akt是否是膀胱肌肉生长所必需的，并且还将知道可能介导膀胱肌肉对肥大信号的反应的牵张响应性Akt调节基因的身份。从这些研究中获得的信息将支持和告知未来的研究，将致力于阐明膀胱肌肉中Akt调节基因的作用机制。

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.