Regulation of Bladder Smooth Muscle Hyperplasia

膀胱平滑肌增生的调节

• 批准号: 6899313
• 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/6899313
• 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，膀胱肌肉经历肥大作为对尿流出阻力增加的代偿反应。如果梗阻变成慢性，膀胱壁顺应性由于过度肥大和纤维化而降低。顺应性差可能导致膀胱输尿管反流、肾积水，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。使用膀胱壁的模型，其中膀胱SMC被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p27 KIP 1通过SMC内张力增加的发展而下调。同样，p27 KIP 1在膀胱出口梗阻的小鼠膀胱壁中被发现在体内下调。然后，使用基因操作的小鼠，候选人已经发现，响应于牵拉的p27 KIP 1的下调是膀胱出口梗阻期间膀胱SMC增生所必需的，并且p27 KIP 1的缺失足以降低膀胱SMC的增生反应的阈值。 候选人还确定了第二种蛋白Skp 2的上调对于p27 KIP 1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Skp 2蛋白的稳定性来调节Skp 2水平，但我们发现张力增加会上调Skp 2的转录表达。候选人希望在细胞周期控制和转录调控专家Steven Weintraub和道格拉斯Dean博士的指导下扩展这些研究。具体地，候选人计划：1）鉴定介导Skp 2启动子活性响应于膀胱平滑肌中张力增加而增加的转录因子; 2）鉴定特定目标1中鉴定的转录因子通过膀胱的机械拉伸调节的机制; 3）检测p27 KIP 1苏氨酸187和丝氨酸10磷酸化的变化，其响应膀胱壁张力的变化而发生。 通过这些研究，候选人希望描绘调节膀胱平滑肌细胞增生对膀胱出口梗阻的反应的信号转导途径，试图找到新的干预靶点，以防止解剖或功能性膀胱出口梗阻发生的膀胱顺应性病理变化。这种性质的工作可能会降低由膀胱出口梗阻引起的发病率和死亡率。