Role of Mechanotransduction in detrusor over activity

描述（由申请人提供）：逼尿肌的机械敏感性定义为平滑肌细胞产生不依赖于外部刺激的机械活动的能力。在膀胱充盈期间，通常没有副交感神经从脊髓流出，然而，膀胱产生张力并且还表现出非同步的局部收缩和松弛。机械感觉机制的病理变化可能导致逼尿肌过度活动（DO）的发展，逼尿肌过度活动（DO）是下尿路的几种功能障碍的共同症状，包括膀胱过度活动症、膀胱阻塞、尿失禁和膀胱疼痛综合征。该建议的中心假设是，膀胱平滑肌细胞（BSMC）中的机械感觉和机械转导受损导致人膀胱对生理牵拉和逼尿肌过度活动的异常反应，这是由于机械门控双孔结构域（K2 p，KCNK）K+通道的变化。动物数据和我们的初步研究结果表明，牵张激活的双孔结构域（K2 p，KCNK）钾离子通道在膀胱机械敏感性中起着关键作用。我们还确定了TREK-1通道是人逼尿肌中牵张激活的K2 p通道的主要表达成员。具体目标1将确定无逼尿肌过度活动和逼尿肌过度活动患者的人膀胱平滑肌细胞中牵张激活K+（K2 p）通道的表达和功能水平的差异。具体目标2将评价TREK-1和人BSMC中细胞骨架（肌动蛋白微丝、小窝蛋白、膜脂质）之间的相互作用，并比较TREK-1调节蛋白在正常与过度活跃的人逼尿肌中的作用。具体目标3将测试基因疗法（通过siRNA的基因沉默和通过saRNA的基因激活）在调节人BSMC中TREK-1的表达和功能中的功效，以有效调节膀胱充盈期间过度活动的逼尿肌对牵拉的异常反应。本提案的总体目标是阐明异常机械敏感性和人逼尿肌对与DO患者肌源性张力增加和自发性非排尿性收缩相关的生理牵拉的反应改变的细胞和分子机制。拟议的研究将阐明人类膀胱和特发性DO患者中机械敏感性和机械转导的细胞机制，并为开发新的药物干预和治疗膀胱功能障碍的创新策略提供新的信息。

DESCRIPTION (provided by applicant): Mechanosensitivity of the detrusor is defined as the ability of smooth muscle cells to generate mechanical activity independent of external stimuli. During bladder filling, there is usually no parasympathetic outflow from the spinal cord, however, the bladder develops tone and also exhibits non- synchronized local contractions and relaxations. Pathological changes in mechanosensory mechanisms may lead to the development of detrusor overactivity (DO) which is a co-symptom of several dysfunctions of the lower urinary tract including overactive bladder, obstructed bladder, urinary incontinence, and bladder pain syndrome. The central hypothesis of this proposal is that impaired mechanosensation and mechanotransduction in bladder smooth muscle cells (BSMC) results in the abnormal response of the human bladder to physiological stretch and detrusor overactivity due to the changes in mechano-gated two-pore domain (K2p, KCNK) K+ channels. Animal data and our preliminary results from the human detrusor suggest that stretch-activated two-pore domain (K2p, KCNK) K+ channels play a critical role in bladder mechanosensitivity. We also established that TREK-1 channel is a predominantly expressed member of stretch-activated K2p channels in the human detrusor. Specific Aim 1 will identify differences in the level of expression and function of stretch-activated K+ (K2p) channels in human bladder smooth muscle cells in patients without and with detrusor overactivity. Specific Aim 2 will evaluate interactions between TREK-1 and cytoskeleton (actin microfilaments, caveolin, membrane lipids) in human BSMC and compare the role of TREK-1 modulating proteins in normal vs. overactive human detrusor. Specific Aim 3 will test the efficacy of gene therapies (gene silencing by siRNA and gene activation by saRNA) in modulating the expression and function of TREK-1 in human BSMC in order to effectively regulate an abnormal response of the overactive detrusor to stretch during bladder filling. The overall objective of this proposal is to investigat cellular and molecular mechanisms of abberant mechanosensitivity and altered response of the human detrusor to physiological stretch associated with increased myogenic tone and spontaneous non-voiding contractions in patients with DO. Proposed studies will clarify the cellular mechanisms of mechanosensitivity and mechanotransduction in the human bladder and in patients with idiopathic DO, and provide new information for the development of new pharmacological interventions and innovative strategies for the treatment of urinary bladder dysfunctions.