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独立于外部刺激产生机械活动的能力。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不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，这是多种下尿路功能障碍的共同症状，包括膀胱过度活动症、膀胱梗阻、尿失禁和膀胱疼痛综合征。该提议的中心假设是，膀胱平滑肌细胞（BSMC）的机械感觉和机械转导受损，由于机械门控两孔域（K2p、KCNK）K通道的变化，导致人类膀胱对生理拉伸和逼尿肌过度活动的异常反应。动物数据和我们对人类逼尿肌的初步结果表明，拉伸激活的双孔结构域（K2p、KCNK）K 通道在膀胱机械敏感性中发挥着关键作用。我们还确定 TREK-1 通道是人类逼尿肌中拉伸激活的 K2p 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的患者和患有逼尿肌过度活动的患者中人膀胱平滑肌细胞中拉伸激活的 K (K2p) 通道的表达水平和功能差异。具体目标 2 将评估 TREK-1 和人 BSMC 中细胞骨架（肌动蛋白微丝、小窝蛋白、膜脂）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进行基因沉默和通过saRNA进行基因激活）在调节人BSMC中TREK-1的表达和功能方面的功效，以有效调节过度活跃的逼尿肌在膀胱充盈过程中对拉伸的异常反应。该提案的总体目标是研究异常机械敏感性的细胞和分子机制，以及人类逼尿肌对生理拉伸的反应改变，这些生理拉伸与 DO 患者肌原性张力增加和自发性非排尿性收缩相关。拟议的研究将阐明人类膀胱和特发性溶解氧患者的机械敏感性和机械传导的细胞机制，并为开发新的药物干预措施和治疗膀胱功能障碍的创新策略提供新信息。

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.