Regulation of Bladder Smooth Muscle Hyperplasia

膀胱平滑肌增生的调节

• 批准号: 6788059
• 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/6788059
• 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)： 当膀胱出口受阻时，膀胱肌肉肥大，以此作为对尿流阻力增加的代偿反应。如果梗阻变为慢性，膀胱壁的顺应性会因过度肥大和纤维化而降低。顺应性差可能导致膀胱输尿管返流、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控膀胱肥大反应的分子调控机制。 这种反应的一个组成部分是膀胱平滑肌细胞(SMC)的增殖。通过使用膀胱壁模型，将膀胱SMC种植在胶原基质中，并受到不同程度的收缩抵抗，候选人发现，细胞周期控制蛋白p27KIP1受到SMC内张力增加的下调。类似地，p27KIP1在体内被发现在伴有膀胱出口梗阻的小鼠膀胱壁中下调。然后，使用基因操作的小鼠，候选人发现，在膀胱出口梗阻期间，拉伸反应p27KIP1的下调对于膀胱SMC增生是必要的，并且p27KIP1的丢失足以降低膀胱SMC增殖反应的阈值。 候选人还确定，第二种蛋白Skp2的上调对于p27KIP1的下调和膀胱SMC的增生性反应都是必要的。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的水平，但我们发现，张力的增加上调了Skp2的转录表达。这位候选人希望在细胞周期控制和转录调控专家史蒂文·温特劳布博士和道格拉斯·迪恩博士的指导下延长这些研究。具体地说，候选人计划：1)鉴定转录因子(S)，该转录因子介导Skp2启动子活性的增加，以响应膀胱壁张力的增加；2)鉴定特定目的1中鉴定的转录因子(S)受膀胱机械拉伸调节的机制(S)；3)检测p27KIP1，苏氨酸187和丝氨酸10的磷酸化变化，以响应膀胱壁张力的变化。 通过这些研究，候选人希望勾勒出调控膀胱SMC对膀胱出口梗阻的增殖反应的信号转导通路，试图找到新的干预靶点，以防止发生在解剖性或功能性膀胱出口梗阻时的膀胱顺应性的病理变化。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。