Sorbs2 targeting and BK channel regulation in the coronary artery of patients with type 1 diabetes

项目摘要 1型糖尿病(T1D)与冠心病密切相关。然而，分子机制 冠脉血管病变，尤其是冠脉平滑肌病变 T1D不完整。血管BK通道，由四个成孔亚基(BK-α)和四个调节亚基组成 亚基(BK-β1)，在冠状动脉平滑肌细胞(SMC)中密集表达，是一个关键的 冠脉血流量和心功能的决定因素。在过去的10年里，我们和其他调查人员 已经证明，由于氧化增加，T1D动物的冠状动脉BK通道功能受损 应激，它会导致心肌缺血的更糟糕的结果。然而，我们所知道的大部分 冠状动脉BK通道异常在T1D是从动物获得的，大多数研究集中在 糖尿病患者BK-β-1表达异常。含有Sorbin和SH3结构域的蛋白2(Sorbs2)是 血管平滑肌细胞中的细胞骨架蛋白。Sorbs2在心血管组织中大量表达，是一种 NRF2的下游目标。然而，Sorbs2在血管病理生理学中的作用尚不清楚。我们有 令人兴奋的初步结果表明，Sorbs2与BK-α和BK-β1蛋白相互作用并调节BK 冠脉SMC中的通道表达。有趣的是，Sorbs2基因敲除小鼠有许多共同的特征 糖尿病合并冠状动脉BK通道病变，尽管血糖正常且不肥胖，表明Sorbs2 缺乏是血管BK通道病的独立风险。重要的是，Sorbs2的表达显著 T1D患者冠状动脉明显减少。与T2D患者不同的是，BK-α的表达，而BK-DNA的表达 β-1在T1D患者冠脉平滑肌细胞中显著降低。然而，Sorbs2在冠脉病变中的作用 人类T1D的BK经络病变和血管病变尚未建立，其潜在机制 T1D患者冠脉SMC中BK-α表达下调的机制尚不清楚。在这个项目中， 我们将利用T1D患者的人体冠状动脉可用性，这些患者计划在 在罗切斯特的梅奥诊所进行心脏手术，以验证我们的假设，即Sorbs2的下调 T1D患者冠状动脉中BK通道和血管功能障碍的表达 药物激活Nrf2增加Sorbs2的表达保护冠状动脉BK通道功能 T1D对人体组织血管反应性的影响。这项研究的结果将提供对分子的新见解 T1D中BK通道病变和冠状动脉病变的机制，并可能有助于开发新的 T1D患者心血管并发症的治疗策略。

Project Summary Type 1 diabetes (T1D) is strongly associated with coronary heart disease. However, the molecular mechanism underlying coronary vascular pathology, especially coronary arterial smooth muscle pathology in human with T1D is incomplete. Vascular BK channels, composed of four pore-forming subunits (BK-α) and four regulatory subunits (BK-β1), are densely expressed in coronary artery smooth muscle cells (SMCs) and are a key determinant of coronary blood flow and cardiac function. Over the last 10 years, we and other investigators have demonstrated that coronary BK channel function is impaired in T1D animals due to increased oxidative stress and it contributes to a worse outcome in myocardial ischemia. However, most of our knowledge of coronary BK channel dysregulation in T1D is obtained from animals and most of studies are focused on the BK-β1 dysregulation in diabetes. The Sorbin and SH3 domain-containing protein 2 (Sorbs2) is a component of cytoskeleton proteins in vascular SMCs. Sorbs2 is abundantly expressed in cardiovascular tissues and is a downstream target of Nrf2. However, the role of Sorbs2 in vascular pathophysiology is unknown. We have exciting preliminary results showing that Sorbs2 interacts with BK-α and BK-β1 protein and regulates BK channel expression in coronary SMCs. Interestingly, Sorbs2 knockout mice share many common features of coronary BK channelopathy with diabetes, despite being normoglycemic and not obese, indicating that Sorbs2 deficiency is an independent risk of vascular BK channelopathy. Importantly, Sorbs2 expression is significantly reduced in coronary arteries of patients with T1D. Unlike T2D patients, the expression of BK-α, but that of BK- β1, is markedly reduced in the coronary SMCs of patients with T1D. However, the role of Sorbs2 on coronary BK channelopathy and vasculopathy of human T1D has not been established, and the underlying mechanisms regarding the downregulation of BK-α expression in coronary SMCs of T1D patients is unclear. In this project, we will take advantage of the availability of human coronary arteries from T1D patients who are scheduled for cardiac surgery at Mayo Clinic in Rochester (MN) to test our hypothesis that downregulation of Sorbs2 expression contributes to BK channel and vascular dysfunction in the coronary arteries of T1D patients and increase of Sorbs2 expression by pharmacological Nrf2 activation protects coronary BK channel function and vasoreactivity in human tissues with T1D. Results from this study will provide novel insights into the molecular mechanisms underlying BK channelopathy and coronary vasculopathy in T1D and may help develop new strategies for the treatment of cardiovascular complications in T1D patients.