The Role of Notch Signaling in Type 2 Diabetic Coronary Microvascular Disease

总结 2型糖尿病（T2 DM）的心脏病与冠状动脉疾病的严重程度直接相关， 这导致冠状动脉血流受损和心肌梗塞（MI）风险增加。T2 DM患者 2-4发生MI的可能性是非糖尿病患者的两倍。虽然内皮功能障碍和 已知动脉粥样硬化会降低T2 DM患者的冠状动脉血流量（CBF），但其潜在机制尚不清楚。 知道的不良冠状动脉阻力微血管（CRM）重塑是T2 DM诱导的T2 DM的关键介质。 心血管疾病Trask实验室发表的研究表明， 早期在T2 DM（db/db）小鼠和患有代谢综合征的猪中，导致CBF受损。虽然机制 尽管目前还不清楚哪些因素控制CRM重塑，但我们的初步数据表明Jagged 1（Jag 1）/Notch信号转导受损。 已知Notch信号通路促进内皮细胞（EC）和血管内皮细胞（VCAM）之间的通讯。 平滑肌细胞（VSMCs）。我们发现Jag 1和Notch 3在T2 DM（db/db）小鼠的CRMs中的表达是 缺乏EC表达的Jag 1或Notch 3缺失小鼠的CBF受损与T2 DM相似 (db/db）小鼠。此外，EC-Jag 1缺陷小鼠有向内CRM重塑的证据。另外我们 在糖尿病小鼠和猪的标准物质中，以及在EC-Jag 1- 缺陷小鼠，表明在肌内皮连接处（MEJ）的异细胞EC-VSMC通讯 可能会在所有模型中被破坏。我们最近的研究确定Notch 3和Jag 1在MEJ的正常CRM。 根据我们收集的初步数据，我们的总体假设是T2 DM患者的冠状动脉血流量减少 由EC和VSMC之间受损的Jag 1/Notch信号驱动。我们将使用一个 整合方法，结合遗传缺陷小鼠模型，EC-VSMC共培养技术，单一 细胞转录组学和转基因/药物拯救实验：具体目的是：检验这一假设 T2 DM导致CRM中Jag 1/Notch信号传导的破坏，并定义了这种机制。目标2.确定 如果异常的Jag 1/Notch信号通路有助于T2 DM患者的不良冠状动脉微血管重构， 遗传学和转录组学方法。目标3。检验Jag 1/Notch信号传导激活可以 预防和/或治疗T2 DM诱导的冠状动脉微血管重构。这些研究将是第一个 证明Notch信号传导是CRM重塑和受损CBF的核心， 可能逆转T2 DM患者的不良CRM重塑和CBF减少。

Summary Heart disease in type 2 diabetes mellitus (T2DM) is directly related to the severity of coronary artery disease, which results in impaired coronary blood flow and increased risk of myocardial infarction (MI). T2DM patients are 2-4 times more likely to experience MI than non-diabetic patients. Although endothelial dysfunction and atherosclerosis are known to decrease coronary blood flow (CBF) in T2DM, the underlying mechanisms are not known. Adverse coronary resistance microvessel (CRM) remodeling is a critical mediator of T2DM-induced cardiovascular disease. Published studies from the Trask lab show that structural remodeling of CRMs occurs early in T2DM (db/db) mice and pigs with metabolic syndrome, leading to impaired CBF. While the mechanisms that govern CRM remodeling are unclear, our preliminary data point to impaired Jagged1 (Jag1)/Notch signaling. The Notch signaling pathway is known to facilitate communication between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). We found that expression of Jag1 and Notch3 in CRMs of T2DM (db/db) mice is reduced, and that mice lacking EC-expressed Jag1, or Notch3-null mice had impaired CBF similar to T2DM (db/db) mice. Furthermore, EC-Jag1-deficient mice have evidence of inward CRM remodeling. In addition, we have shown a significant reduction in fenestrae in the of CRMs of diabetic mice and pigs, and in EC-Jag1- deficient mice, suggesting that heterocellular EC-VSMC communication at the myoendothelial junction (MEJ) maybe be disrupted in all models. Our recent studies identified Notch3 and Jag1 at the MEJ of normal CRMs. Based upon our collective preliminary data, our overall hypothesis is that reduced coronary blood flow in T2DM is driven by impaired Jag1/Notch signaling between ECs and VSMCs. We will test this hypothesis using an integrative approach, combining genetically-deficient mouse models, EC-VSMC co-culture techniques, single- cell transcriptomics, and transgenic/drug rescue experiments: The Specific Aims are: Aim1. Test the hypothesis that T2DM causes a disruption of Jag1/Notch signaling in CRMs and define this mechanism. Aim 2. Determine if aberrant Jag1/Notch signaling contributes to adverse coronary microvascular remodeling in T2DM using genetic and transcriptomic approaches. Aim 3. Test the hypothesis that activation of Jag1/Notch signaling can prevent and/or treat T2DM-induced coronary microvascular remodeling. These studies will be the first to demonstrate Notch signaling is central to CRM remodeling and impaired CBF, and that correction of this pathway may reverse adverse CRM remodeling and reduced CBF in T2DM.