Role of calcium sensitization in diabetes-induced erectile dysfunction

描述（申请人提供）：据估计，平均而言，1000万糖尿病（DM）男性中有50%患有勃起功能障碍（艾德），1型和2型DM几乎同等地与ED相关。尽管已经开发了有效的口服活性PDE 5抑制剂来治疗艾德，很大比例的糖尿病男性（估计高达50%）仍然对这种疗法难以治疗。该建议的具体假设是，糖尿病诱导的艾德中海绵体平滑肌（CCSM）基础张力增加和CCSM无法适当松弛是由SM钙敏化通过抑制平滑肌肌球蛋白磷酸酶（SMMP）活性介导的。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。使用来自I型和II型糖尿病大鼠、艾德患者以及培养的CCSM细胞的CCSM，我们的假设将通过实现以下具体目标来解决：1）使用I型和II型糖尿病大鼠模型确定a）糖尿病和艾德之间的精确相关性，B）“钙致敏”酶Rho-激酶的表达/活性是否增加，韩国三家知名监管机构（RhoA、内皮素和鞘氨醇-1-磷酸）和/或SMMP抑制蛋白CPI-17的变化，以及这些变化与艾德和c）是否存在促进平滑肌“钙脱敏”的分子的同时下调的相关性（即PKG-1和telokin），2）确定a）是否可以在分离的CCSM细胞中诱导响应于实验诱导的糖尿病而发生的“钙敏化/脱敏”相关分子的表达/活性的类似改变（例如高葡萄糖、高胰岛素、外源性Et-1等）和B）药理学抑制“钙致敏”分子或质粒介导的“钙脱敏”分子过表达以预防、减轻或逆转艾德的能力以及这些作用的机制和3）为了确定，使用从接受阴茎手术治疗艾德的男性中常规分离的人CCSM样本，“钙敏感/脱敏”的改变是否通过完成上述研究获得的数据应该提供敏锐和新颖的见解研究糖尿病诱导的艾德的分子机制，并确定哪些“钙致敏/脱敏”途径可作为治疗ED的有吸引力的分子治疗靶点。此外，由于“钙致敏”途径的类似变化开始出现在糖尿病血管SM中，从这些研究中获得的知识可能对糖尿病诱导的泌尿生殖系统以外的病理学有影响。

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.