Role of calcium sensitization in diabetes-induced erectile dysfunction

描述（由申请人提供）：据估计，平均而言，1000万男性糖尿病（DM）患者中有50%患有勃起功能障碍（ED）， 1型和2型糖尿病与ED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%）仍然难以接受这种治疗。该建议的具体假设是，在糖尿病诱导的ED中，海绵体平滑肌（CCSM）基底张力增加和无法适当放松CCSM是通过抑制平滑肌肌球蛋白磷酸酶（SMMP）活性介导的SM钙致敏。具体来说，为了解决这一假设，我们将研究直接或间接调节SMMP活性的分子的表达和调节，并阐明它们在“钙致敏/脱敏”途径中所起的作用。使用I型和II型糖尿病大鼠、ED患者的CCSM以及培养的CCSM细胞，我们的假设将通过实现以下具体目标来解决：1)利用I型和II型糖尿病大鼠模型，确定a)糖尿病与ED之间的精确相关性，b)糖尿病动物中“钙致敏”酶RhoA激酶、三种已知的ROK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/活性是否增加。以及这些变化与ED的相关性，c)是否同时存在促进平滑肌“钙脱敏”的分子（即PKG-1和端粒蛋白）的下调，2)确定a)在实验诱导的糖尿病中发生的“钙致敏/脱敏”相关分子的表达/活性的类似改变是否可以在离体CCSM细胞中诱导(如高葡萄糖、高胰岛素、外源性Et-1、b)药物抑制“钙致敏”分子或质粒介导的“钙脱敏”分子过表达预防、减弱或逆转ED的能力及其作用机制。3)利用常规从阴茎手术男性中分离的人类CCSM样本来确定治疗ED的方法。大鼠“钙致敏/脱敏”通路的改变是否会转化为患有ED的糖尿病人。通过完成上述研究获得的数据应该为糖尿病诱导ED的分子机制提供敏锐和新颖的见解，并确定哪些“钙致敏/脱敏”通路可能成为ED治疗的有吸引力的分子治疗靶点。由于类似的“钙致敏”通路的变化开始在糖尿病血管性SM中出现，从这些研究中获得的知识可能对糖尿病引起的泌尿生殖系统以外的病理有启示。

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.