Regulation of Skp2 Expression in Urinary Bladder Wall

膀胱壁 Skp2 表达的调控

• 批准号: 6837965
• 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 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6837965
• 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.

正常的尿道是高度扩张的。因此，在尿道和尿道周围肌肉组织松弛时，膀胱壁张力的小幅增加会导致高尿流率。然而，面对功能性或结构性膀胱出口梗阻，膀胱壁中必须产生更高水平的机械张力，以克服尿液流出阻力的增加。为了满足这种需要，膀胱壁肥厚。肥大 是细胞大小（细胞肥大）和细胞数量（细胞增生）增加的结果。如果膀胱出口梗阻是慢性的，肥大就会过度。膀胱壁过度肥大导致的尿路生理紊乱可导致排空不良继发的慢性尿路感染和膀胱输尿管反流继发的肾功能衰竭等问题。由于这些问题的可能性，我们试图定义介导这些问题的信号转导途径。 膀胱壁肥大对机械张力增加的反应。我们通过关注反应的增生成分开始我们的研究。我们发现，当膀胱出口梗阻时，膀胱壁组织中 F-box 蛋白 Skp2 的表达上调。 Skp2 对于破坏抑制细胞周期进程的蛋白质 p27(KIP1) 非常重要。因此我们认为 Skp2 表达的增加将被证明是 膀胱壁增生对膀胱出口梗阻的反应很重要。因此，我们研究了 Skp2 敲除小鼠膀胱出口梗阻的影响。事实上，我们发现正常膀胱阻塞时发生的增殖反应在 Skp2 敲除小鼠的阻塞膀胱中不存在。这表明 Skp2 的上调是膀胱出口梗阻增生反应的关键组成部分。然后我们研究了当存在膀胱出口时 Skp2 表达上调的机制 梗阻。重要的是，虽然 Skp2 在蛋白质稳定性水平上受到生长因子的调节，但我们发现继发于膀胱出口梗阻的膀胱壁中产生的机械张力的增加通过增加 Skp2 RNA 的转录率来上调 Skp2 的表达。由于 Skp2 表达在膀胱出口梗阻的增生反应中的重要性，我们现在将尝试描述当膀胱出口梗阻时上调 Skp2 表达的信号转导途径。这些研究旨在确定干预目标，以抑制肥大反应 膀胱壁因膀胱出口梗阻而发生。