Role of calcium sensitization in diabetes-induced erectile dysfunction

描述(申请人提供)：据估计，在1000万患有糖尿病(DM)的男性中，平均有50%患有勃起功能障碍(ED)，1型和2型DM与勃起功能障碍的相关性几乎相同。尽管已经开发出有效的口服活性PDE5抑制剂来治疗ED，但很大比例的糖尿病男性(估计高达50%)仍然对这种治疗无效。这一设想的具体假设是，糖尿病引起的ED患者海绵体平滑肌(CCSM)基础张力增加和CCSM不能正常松弛是由SM钙增敏通过抑制平滑肌肌球蛋白磷酸酶(SMMP)活性而实现的。具体地说，为了解决这一假说，我们将研究直接或间接调节SMMP活性的分子的表达和调控，并阐明它们在“钙敏化/脱敏”途径中所起的作用。通过使用来自I型和II型糖尿病大鼠、ED患者以及培养的CCSM细胞的CCSM，我们的假设将通过实现以下特定目标来实现：1)使用I型和II型糖尿病大鼠模型确定糖尿病和ED之间的确切相关性，b)糖尿病动物中是否存在“钙敏化”酶Rho-Kinase、三种公认的韩国调节因子(RhoA、内皮素和鞘氨醇-1-磷酸)和/或SMMP抑制蛋白CPI-17的表达/活性增加，以及这些变化与ED和c)是否同时下调了促进平滑肌“钙脱敏”的分子(即PKG-1和telokin)，2)以确定a)是否可以在分离的CCSM细胞中诱导对实验诱导的糖尿病的反应而发生的“钙敏化/脱敏”相关分子的表达/活性的类似变化(例如，高糖、高胰岛素、外源性ET-1等)。以及b)药物抑制“钙增敏”分子或质粒介导的“钙脱敏”分子过表达以预防、减弱或逆转ED的能力以及这些作用的机制；3)使用从接受阴茎手术治疗ED的男性常规分离的人CCSM标本，确定大鼠的“钙增敏/脱敏”途径的变化是否转化为患有ED的糖尿病人。上述研究的完成将为糖尿病引起的ED的分子机制提供敏锐而新颖的见解，并确定哪些“钙增敏/脱敏”途径可能成为治疗ED的有吸引力的分子治疗靶点。此外，由于糖尿病血管SM的“钙敏化”途径也开始出现类似的变化，从这些研究中获得的知识可能会对糖尿病引起的泌尿生殖系统以外的病理产生影响。

DESCRIPTION (provided by applicant): It is estimated that, on average, 50% of the 10 million men with diabetes mellitus (DM) have erectile dysfunction (ED) with both Type 1 and Type 2 DM nearly equally associated with ED. Although efficacious orally active PDE5 inhibitors have been developed to treat ED, a large percentage of diabetic men (with estimates as high as 50%) remain refractory to this therapy. The specific hypothesis of this proposal is that an increased corpus cavernosum smooth muscle (CCSM) basal tone and inability to properly relax the CCSM in diabetes-induced ED is mediated by SM calcium sensitization via inhibition of smooth muscle myosin phosphatase (SMMP) activity. Specifically, to address this hypothesis, we will examine the expression and regulation of molecules that either directly or indirectly regulate SMMP activity and the roles that they play in "calcium sensitization/desensitization" pathways will be elucidated. Using CCSM from Type- I and Type II diabetic rats, patients with ED, as well as cultured CCSM cells, our hypothesis will be addressed by accomplishing the following specific aims: 1) To determine, using both Type I and Type II rat models of diabetes a) the precise correlation between diabetes and ED, b) whether there is an increased expression/activity of the "calcium-sensitizing" enzyme Rho-kinase, three well-established ROK regulators (RhoA, endothelin and sphingosine-1-phosphate) and/or the SMMP inhibitory protein CPI-17 in diabetic animals, and the correlation of these changes with ED and c) if there is a simultaneous downregulation of molecules that promote the "calcium desensitization" of smooth muscle (namely PKG-1 and telokin), 2) To determine a) whether similar alterations in the expression/activity of "calcium sensitization/desensitization"- associated molecules that occur in response to experimentally-induced diabetes can be induced in isolated CCSM cells (e.g. high glucose, high insulin, exogenous Et-1, etc.) and b) the ability of pharmacological inhibition of "calcium sensitization" molecules or plasmid-mediated overexpression of "calcium desensitization" molecules to prevent, attenuate or reverse ED and the mechanisms for these effects and 3) To determine, using human CCSM specimens routinely isolated from men undergoing penile surgery to treat ED, whether alterations in the "calcium sensitization/desensitization" pathways in the rat translate to diabetic humans with ED. The data obtained by the completion of the studies described above should provide keen and novel insight into the molecular mechanism for diabetes-induced ED and also establish which "calcium sensitization/desensitization" pathways may serve as attractive molecular therapeutic targets for the treatment of ED. Moreover, since similar changes in "calcium sensitization" pathways are beginning to emerge in diabetic vascular SM, knowledge gained from these studies may have implications in diabetes- induced pathologies beyond the urogenital system.