Regulation of Skp2 Expression in Urinary Bladder Wall

膀胱壁 Skp2 表达的调控

• 批准号: 6919991
• 负责人: Steven Jay Weintraub
• 金额: $ 15.3万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-15 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6919991
• 关键词: biological signal transduction; calcineurin; cell proliferation; clinical research; gel mobility shift assay; gene expression; genetic regulation; green fluorescent proteins; laboratory mouse; polymerase chain reaction; serine threonine protein kinase; smooth muscle; urinary bladder; urinary bladder epithelium; urinary tract obstruction; western blottings

The normal urethra is highly distensible. Therefore, upon relaxation of the urethral and periurethral musculature, a small increase in bladder wall tension results in high urine flow rates. However, in the face of either a functional or structural bladder outlet obstruction, an increased level of mechanical tension must develop in the bladder wall to overcome the increased resistance to urine outflow. To meet this need, the bladder wall hypertrophies. The hypertrophy is a result of both an increase in cell size (cellular hypertrophy) and cell number (cellular hyperplasia). If the bladder outlet obstruction is chronic, the hypertrophy becomes excessive. The derangement in urinary tract physiology that results from excessive bladder wall hypertrophy can result in such problems as chronic urinary tract infection secondary to poor emptying and renal failure secondary to vesicoureteral reflux. Because of the potential for these problems, we have sought to define the signal transduction pathways that mediate the bladder wall hypertrophic response to increased mechanical tension. We initiated our studies by focusing on the hyperplastic component of the response. We found that when there is a bladder outlet obstruction, expression of the F-box protein Skp2 is upregulated in the tissue of the bladder wall. Skp2 is important for the destruction of a protein, p27(KIP1), that inhibits cell cycle progression. Thus we thought that the increased expression of Skp2 would prove to be important in the bladder wall hyperplastic response to bladder outlet obstruction. We, therefore, examined the effect of bladder outlet obstruction in Skp2-knockout mice. Indeed, we found that the proliferative response that occurs when the normal bladder is obstructed is absent in the obstructed bladder of Skp2-knockout mice. This indicates that the upregulation of Skp2 is a critical component of the hyperplastic response to bladder outlet obstruction. We then examined the mechanism by which expression of Skp2 is upregulated when there is a bladder outlet obstruction. Importantly, whereas Skp2 is regulated by growth factors at the protein stability level, we found that the increase in mechanical tension that develops in the bladder wall secondary to a bladder outlet obstruction upregulates expression of Skp2 by increasing the rate of transcription of Skp2 RNA. Because of the importance of Skp2 expression in the hyperplastic response to bladder outlet obstruction, we will now attempt to delineate the signal transduction pathways that upregulate Skp2 expression when there is bladder outlet obstruction. These studies will be aimed at identifying targets for intervention to inhibit the hypertrophic response of the bladder wall that occurs in response to bladder outlet obstruction.

正常的尿道高度扩张。因此，在放松尿道和尿道周围肌肉组织后，膀胱壁张力的少量增加导致尿液流量高。但是，面对功能性或结构性膀胱出口阻塞，必须在膀胱壁中发展机械张力的水平增加，以克服对尿液流出的耐药性。为了满足这种需求，膀胱壁肥大。肥大 是细胞尺寸（细胞肥大）和细胞数（细胞增生）增加的结果。如果膀胱出口阻塞是慢性的，则肥大会过多。由于膀胱肥大过多而导致的尿路生理的危险会导致诸如慢性尿路感染继发于较差的空排空和肾脏衰竭之后，其继发于囊泡级反流。由于可能存在这些问题，我们试图定义介导的信号转导途径 膀胱壁对机械张力增加的反应。我们通过关注响应的增生成分来开始研究。我们发现，当存在膀胱出口阻塞时，F-box蛋白SKP2的表达在膀胱壁的组织中上调。 SKP2对于抑制细胞周期进程的蛋白质P27（KIP1）的破坏很重要。因此，我们认为SKP2的表达增加将被证明是 对于膀胱壁对膀胱出口阻塞的增生反应很重要。因此，我们检查了SKP2敲除小鼠中膀胱出口阻塞的影响。确实，我们发现，在SKP2敲除小鼠的膀胱中，没有阻塞正常膀胱被阻塞时发生的增殖反应。这表明SKP2的上调是对膀胱出口阻塞的增生反应的关键组成部分。然后，我们检查了有膀胱出口时SKP2表达上调的机制 梗阻。重要的是，尽管SKP2受蛋白质稳定性水平下的生长因子调节，但我们发现，在膀胱壁中，膀胱出口阻塞的膀胱壁中发生的机械张力增加通过增加SKP2 RNA的转录速率而上调SKP2的表达。由于SKP2表达在对膀胱出口阻塞的增生反应中的重要性，我们现在将尝试描述当存在膀胱出口阻塞时上调SKP2表达的信号转导途径。这些研究将旨在识别干预措施以抑制抑制肥厚的反应 响应膀胱出口阻塞而发生的膀胱壁。