Role of Mechanotransduction in detrusor over activity

描述(申请人提供)：逼尿肌的机械敏感性被定义为平滑肌细胞独立于外界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，也表现出非同步的局部收缩和松弛。机械感觉机制的病理改变可能导致逼尿肌过度活动(DO)，这是下尿路功能障碍的共同症状，包括膀胱过度活动、膀胱梗阻、尿失禁和膀胱痛综合征。这一假设的核心假设是，由于机械门控双孔结构域(K2p，KCNK)钾通道的改变，膀胱平滑肌细胞(BSMC)的机械感觉和机械转导受损，导致人的膀胱对生理性牵张和逼尿肌过度活动的异常反应。动物数据和我们在人逼尿肌上的初步结果表明，拉伸激活的双孔结构域(K2p，KCNK)K通道在膀胱机械敏感性中起着关键作用。我们还证实，Trek-1通道是人类逼尿肌中拉伸激活的K2p通道中主要表达的成员。具体目标1将确定在没有和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的差异。特异性目标2将评估Trek-1与人BSMC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调节蛋白在正常和过度活动的人逼尿肌中的作用。目的3检测基因治疗(siRNA沉默基因和Sarna激活基因)对人BSMC中Trek-1表达和功能的影响，以有效调节膀胱充盈过程中过度活动的逼尿肌对拉伸的异常反应。这项建议的总体目标是研究DO患者逼尿肌机械敏感性和生理拉伸反应改变的细胞和分子机制与肌源性张力增加和自发非排尿收缩相关。拟议的研究将阐明人类膀胱和特发性DO患者的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创新策略治疗膀胱功能障碍提供新的信息。

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.