Urothelial ATP Signaling and Diabetic Bladder Dysfunction

描述（由申请人提供）：ATP在膀胱的感觉和运动功能中起重要作用。从副交感神经纤维释放的ATP可以兴奋逼尿肌，并且响应于膀胱扩张从尿道膀胱释放的ATP可以通过激活传入纤维、刺激上皮下肌成纤维细胞和诱导从尿道膀胱释放其他信号分子来间接调节逼尿肌收缩性。病理状态可增加神经原性逼尿肌收缩的嘌呤能成分，也可增加尿路上皮ATP释放。在糖尿病中，各种尿动力学异常可发展，包括膀胱活动增加。我们提出，糖尿病膀胱对嘌呤能刺激的敏感性增加与逼尿肌中特定嘌呤能受体（P2R）亚型的上调有关，ATP信号的放大将直接导致糖尿病膀胱过度活动的发展。基于最近的研究结果，我们现在有证据表明ATP信号在糖尿病膀胱尿道炎中也被放大。P2R，特别是P2X7R和P2X3R亚型的表达在STZ糖尿病大鼠膀胱的尿路上皮中显著增加，并且在STZ糖尿病尿路上皮细胞中对ATP的反应更高。这些发现结合P2X7R激活可诱导ATP和前列腺素（PGE2）释放的证据表明，糖尿病膀胱不仅对ATP敏感，而且ATP和PGE2从尿路上皮细胞释放增加。在这种情况下，来自膀胱的传入信号以及尿路上皮细胞、上皮下肌成纤维细胞和平滑肌细胞的通信能力将显著增强，并可能有助于增加糖尿病患者的膀胱活动。为了验证糖尿病增加膀胱间室的尿路上皮ATP信号传导和通信，以及膀胱内和膀胱的增强的ATP信号传导有助于糖尿病膀胱功能障碍的发展的假设，我们将使用分子生物学，生物化学，药理学，体外亚细胞成像和整个动物生理学方法的组合。这些研究有望导致新的理解特定的膜受体和通道蛋白之间的相互作用，参与细胞间的信号传导之间的尿路上皮和膀胱平滑肌，并揭示新的治疗目标和策略，以改善糖尿病膀胱功能障碍的症状。公共卫生相关性：本RO1申请中提出的研究有望进一步了解膀胱尿路上皮、上皮下和平滑肌间室之间的相互作用，以及尿路上皮ATP信号传导主要组分表达的变化如何促进糖尿病膀胱功能障碍的发展。

DESCRIPTION (provided by applicant): ATP plays important roles in the sensory and motor functions of the urinary bladder. ATP released from parasympathetic fibers can excite the detrusor muscle, and ATP released from the urothelium in response to bladder distension can indirectly modulate detrusor contractility by activating afferent fibers, stimulating suburothelial myofibroblasts and inducing release of other signaling molecules from the urothelium. Pathological conditions can increase the purinergic component of the neurogenic detrusor contraction and also augment urothelial ATP release. In diabetes various urodynamic abnormalities can develop, including increased bladder activity. We have proposed that increased sensitivity of diabetic bladders to purinergic stimulation was related to upregulation of specific purinergic receptor (P2R) subtypes in the detrusor muscle, and that amplification of ATP signaling would directly contribute to the development of bladder overactivity in diabetes. Based on recent findings we have now evidence that ATP signaling in also amplified in the diabetic bladder urothelium. Expression of P2Rs, particularly the P2X7R and P2X3R subtypes, is markedly increased in the urothelium of STZ-diabetic rat bladders and responses to ATP are higher in STZ-diabetic urothelial cells. These findings combined with demonstrations that P2X7R activation can induce release of both ATP and prostaglandin (PGE2), suggest that not only the sensitivity to ATP but also ATP and PGE2 release from urothelial cells is increased in diabetic bladders. In this context, afferent signaling from the bladder as well as ability of urothelial cells, suburothelial myofibroblast and smooth muscle cells to communicate would be significantly enhanced and likely contribute to increase bladder activity in diabetes. To test the hypotheses that diabetes increases urothelial ATP signaling and communication between bladder compartments, and that enhanced ATP signaling within and from the bladder contributes to the development of bladder dysfunction in diabetes we will use a combination of molecular biology, biochemistry, pharmacology, in vitro subcellular imaging and whole animal physiology approaches. These studies are expected to lead to novel understanding of the interplay among specific membrane receptors and channel proteins involved in intercellular signaling between urothelium and bladder smooth muscle, and reveal novel therapeutic targets and strategies to ameliorate the symptoms of bladder dysfunction in diabetes. PUBLIC HEALTH RELEVANCE: The studies proposed in this RO1 application are expected to further our understanding of the interactions between the bladder urothelial, suburothelial and smooth muscle compartments and of how changes in the expression of main components of the urothelial ATP signaling contribute to the development of bladder dysfunction in diabetes.