Regulation of Bladder Smooth Muscle Hyperplasia

膀胱平滑肌增生的调节

• 批准号: 7085525
• 负责人: PAUL F AUSTIN
• 金额: $ 12.01万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-15 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7085525
• 关键词: biological signal transduction; cell cycle proteins; cell growth regulation; genetic promoter element; hyperplasia; laboratory mouse; laboratory rat; phosphorylation; smooth muscle; transcription factor; urinary bladder; urinary bladder sphincter disorder

DESCRIPTION (provided by applicant): When the bladder outlet is obstructed, the bladder muscle undergoes hypertrophy as a compensatory response to the increased resistance to urinary outflow. If the obstruction becomes chronic, bladder wall compliance decreases due to excessive hypertrophy and fibrosis. The poor compliance may lead to vesicoureteral reflux, hydronephrosis, and, ultimately, renal failure. Because of its clinical significance, we have begun to study the molecular control mechanisms that regulate the bladder hypertrophic response. One component of this response is the hyperplasia of the bladder smooth muscle cells (SMC). Using a model of the bladder wall in which bladder SMC are seeded in a collagen matrix and subject to varying degrees of resistance to contraction, the candidate has found that the cell cycle control protein p27KIP1 is downregulated by the development of increased tension within the SMC. Similarly, p27KIP1 was found downregulated in vivo in a murine bladder wall with bladder outlet obstruction. Then, using genetically manipulated mice, the candidate has found that the downregulation of p27KIP1 in response to stretch is necessary for bladder SMC hyperplasia during bladder outlet obstruction and that loss of p27KIP1 is sufficient to lower the threshold of the hyperplastic response of bladder SMC. The candidate has also determined that the upregulation of a second protein, Skp2 is necessary for both the downregulation of p27KIP1 and the bladder SMC hyperplastic response. Notably, whereas growth factors regulate Skp2 levels by altering the stability of Skp2 protein, we found that increased tension upregulates transcriptional expression of Skp2. The candidate would like to extend these studies with the guidance of Drs. Steven Weintraub and Douglas Dean who are experts of cell cycle control and transcriptional regulation. Specifically, the candidate plans to: 1) Identify the transcription factor(s) that mediates the increase in Skp2 promoter activity in response to increased tension in bladder smooth muscle; 2) Identify the mechanism(s) by which the transcription factor(s) identified in Specific Aim 1 is regulated by mechanical stretch of the bladder; 3) Examine the changes in phosphorylation of p27KIP1 threonine 187 and serine 10 that occur in response to changes in bladder wall tension. Through these studies, the candidate hopes to delineate the signal transduction pathways that regulate the bladder SMC hyperplastic response to bladder outlet obstruction in an attempt to find new targets for intervention to prevent the pathologic change in bladder compliance that occurs with either anatomic or functional bladder outlet obstruction. Work of this nature may decrease the morbidity and mortality that is caused by bladder outlet obstruction.

描述（由申请人提供）： 当膀胱出口被阻塞时，膀胱肌肉会肥大，作为对尿液流出阻力增加的代偿反应。如果梗阻变成慢性，膀胱壁顺应性会因过度肥厚和纤维化而降低。依从性差可能导致膀胱输尿管反流、肾积水，并最终导致肾功能衰竭。由于其临床意义，我们已经开始研究调节膀胱肥大反应的分子控制机制。 这种反应的一个组成部分是膀胱平滑肌细胞（SMC）的增生。使用膀胱壁模型，其中膀胱 SMC 接种在胶原基质中并受到不同程度的收缩阻力，候选人发现细胞周期控制蛋白 p27KIP1 由于 SMC 内张力增加而下调。同样，p27KIP1 在患有膀胱出口梗阻的小鼠膀胱壁中体内表达下调。然后，使用基因操纵的小鼠，候选人发现 p27KIP1 对拉伸反应的下调对于膀胱出口梗阻期间膀胱 SMC 增生是必要的，并且 p27KIP1 的缺失足以降低膀胱 SMC 增生反应的阈值。 该候选人还确定，第二种蛋白质 Skp2 的上调对于 p27KIP1 的下调和膀胱 SMC 增生反应都是必要的。值得注意的是，虽然生长因子通过改变 Skp2 蛋白的稳定性来调节 Skp2 水平，但我们发现张力的增加会上调 Skp2 的转录表达。候选人希望在博士的指导下扩展这些研究。 Steven Weintraub 和 Douglas Dean 是细胞周期控制和转录调控方面的专家。具体来说，候选人计划： 1) 识别介导 Skp2 启动子活性增加以响应膀胱平滑肌张力增加的转录因子； 2) 确定具体目标 1 中确定的转录因子受膀胱机械拉伸调节的机制； 3) 检查 p27KIP1 苏氨酸 187 和丝氨酸 10 磷酸化的变化，这些变化是响应膀胱壁张力的变化而发生的。 通过这些研究，候选人希望描绘出调节膀胱平滑肌细胞对膀胱出口梗阻的增生反应的信号转导途径，试图找到新的干预目标，以防止解剖性或功能性膀胱出口梗阻发生的膀胱顺应性病理变化。这种性质的工作可以降低由膀胱出口阻塞引起的发病率和死亡率。