Molecular mechanisms of mechanosensing in the urinary tract

点击翻译按钮获取中文摘要

Project Summary Problems with function in the lower urinary tract (LUT) are remarkably common: in adults over 40, up to 70% of all survey respondents report LUT pathologies. This is in part because the physiology of urination (micturition) is complex: it requires smooth muscle in the bladder and urethra to be coordinated with activity in the voluntary, striated muscle of the urethral sphincter. Seven peripheral reflexes enable this coordination, and all of these arise from mechanical cues in the bladder (i.e. bladder stretch) or in the urethra (i.e. urethral fluid flow or distension). Remarkably, we do not know the identity of the molecules or exactly which cell types sense these mechanical forces. For example, two cell types, sensory neurons that innervate the LUT and the urothelial cells in the bladder, are proposed to contribute to these reflexes. Therefore, the details of how these reflexes are initiated and integrated in the system remain poorly understood. I hypothesize that the mechanosensory ion channels PIEZO1 and PIEZO2 mediate mechanosensing in the lower urinary tract. I will use bladder-pressure recordings in combination with electromyography to characterize micturition reflexes, as well as histology and behavior to characterize the expression and the functional role of PIEZOs in urination, specifically as they function in the urothelial cells. I will also test the role of PIEZOs in mediating bladder accommodation responses to fluid filling, as well as their role in mediating pain during pathological conditions like cystitis. Together, these results will delineate the contribution of the mechanotransduction ion channels, specific cell types and peripheral circuitry that facilitate urination. Understanding these processes is an important first step to alleviate the enormous burden of LUT pathologies in humans.