Role of Ectonucleotidase in Voiding Function and Dysfunction

摘要： 下尿路症状(LUTS)影响了很大比例的人群，带来了巨大的经济和 治疗LUT的社会成本和有效药物是有限的。嘌呤能信号是一个突出的 途径失调，这在LUTS中一直被报道。而嘌呤能收缩能力最小 在正常人的膀胱中，它在病人的膀胱中显著增加，更接近于 记录了啮齿动物的生理学。然而，导致这些功能途径潜在机制 目前尚不清楚是否有变化。为了研究这一点，我们鉴定了多种新的功能嘌呤能受体和 膀胱中的调节器。我们已经证明，嘌呤能信号不仅对心脏收缩很重要 由ATP/ADP介导的膀胱壁激活了P2X1/P2Y12信号，但对膀胱也很重要 腺苷介导的松弛激活A2B受体信号转导。此外，A2B受体介导的 松弛信号可完全抑制P2X1/P2Y12介导的收缩。通过比较研究，我们有 定义了一个关键基因-ENTPD1(也称为CD39)-在人和小鼠中差异表达 膀胱(正常人的膀胱比小鼠的高8倍)。ENTPD1是一种限速酶 按顺序折算ATP/ADP/AMP。ENTPD1控制激动剂级联反应的动力学 (ATP和GT；ADP和GT；腺苷)，因此在控制嘌呤能受体的表达和 功能。有趣的是，人类ENTPD1突变已在自身免疫性疾病和 神经退行性疾病，LUTS是这些疾病的突出症状。与此一致的是， 据报道，在LUTS患者的膀胱组织中有ATP水解受损的报道。因此，我们假设 提示ENTPD1是膀胱功能的关键调节因子。作为支持，我们有来自全球Entpd1的初步数据- /-小鼠，表明Entpd1缺失会导致膀胱扩张，并具有异常的排尿表型。我们 我们将通过以下目标来验证我们的假设：(1)我们将产生一种内脏平滑肌特异性 Entpd1基因敲除小鼠模型研究ENTPD1在调节正常逼尿肌中的重要作用 (2)ENTPD1基因突变小鼠模型 ENTPD1的表达水平，以模拟正常(高)和病变(低)的人膀胱，然后 检查排尿功能/功能障碍；(3)通过国家疾病研究交流中心(NDRI) ，我们将获取人膀胱组织，并研究ENTPD1在人膀胱组织中的表达和功能。 男性和女性的膀胱。我们将解开为什么有嘌呤能收缩差异的谜题 人类和啮齿动物的膀胱，男性和女性的膀胱之间，以及正常和患病的膀胱之间 人类的膀胱。我们希望这项研究将大大提高我们对膀胱收缩如何 而松弛受ENTPD1及其相关的嘌呤能信号控制。这些研究具有很高的 有可能为人类LUTS患者引入新的治疗方法，因为有多种靶向选择。

Abstract: Lower urinary tract symptoms (LUTS) impact a large percentage of the population with enormous financial and social costs, and effective drugs for management of LUTS are limited. Purinergic signaling is a prominent dysregulated pathway, which has been consistently reported in LUTS. While purinergic contractility is minimal in normal human bladder, it increases significantly in bladders of human patients, to more closely resembles documented rodent physiology. However, the underlying mechanism which results in these functional pathway alterations is not known. To study this, we have identified multiple novel functional purinergic receptors and modulators in bladder. We have demonstrated that purinergic signaling is not only important for contraction in bladder wall, as mediated by ATP/ADP activated P2X1/P2Y12 signaling, but is also important for bladder relaxation mediated by adenosine activated A2b receptor signaling. Furthermore, A2b receptor mediated relaxation signaling can completely inhibit P2X1/P2Y12 mediated contractions. By comparative studies, we have defined a key gene - ENTPD1 (also known as CD39) – that is differentially expressed in human and mouse bladders (~ 8-fold higher in normal human bladders than in mouse). ENTPD1 is a rate-limiting enzyme converting ATP/ADP/AMP sequentially. ENTPD1 controls the kinetics of an agonist cascade (ATP>ADP>adenosine), and hence plays a critical role in the control of purinergic receptor expression and function. Interestingly, human ENTPD1 mutations have been identified in autoimmune diseases and neurodegenerative disorders, and LUTS is a prominent symptom in these diseases. Consistent with this, impaired ATP hydrolysis has been reported in bladder tissues from LUTS patients. Therefore, we hypothesize that ENTPD1 is a key regulator in bladder function. In support, we have preliminary data from a global Entpd1- /- mouse, indicating that deletion of Entpd1 results in a dilated bladder with abnormal voiding phenotype. We will test our hypothesis through the following aims: (1) We will generate a visceral smooth muscle specific Entpd1 knockout mouse model to demonstrate the critical importance of ENTPD1 in regulating normal detrusor contractility and bladder function; (2) We will use two ENTPD1 mutant mouse models with high and low ENTPD1 expression levels to mimic human bladders that are normal (high) and diseased (low), and then examine voiding function/dysfunction; (3) Through the National Disease Research Interchange (NDRI) network, we will procure human bladder tissues, and study the expression and function of ENTPD1 in the bladders of both sexes. We will solve the puzzles of why there are purinergic contractile differences between human and rodent bladders, between male and female human bladders, and between normal and diseased human bladders. We expect this study to substantially advance our understanding on how bladder contraction and relaxation is controlled by ENTPD1 and its associated purinergic signaling. These studies have high potential to introduce novel therapies for human LUTS patients as there are multiple targetable options.