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

摘要 2型糖尿病(T2 DM)的心脏病与冠状动脉病变的严重程度直接相关， 这会导致冠状动脉血流受损，增加心肌梗死(MI)的风险。2型糖尿病患者 患心肌梗死的可能性是非糖尿病患者的2-4倍。尽管内皮功能障碍和 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 为人所知。冠状动脉阻力微血管(CRM)重构是T2 DM的重要介质 心血管疾病。特拉斯克实验室发表的研究表明，CRM发生结构重塑 在T2 DM(db/db)小鼠和患有代谢综合征的猪的早期，导致脑血流量受损。虽然这些机制 控制CRM重构的因素尚不清楚，我们的初步数据表明Jagged1(Jag1)/Notch信号受损。 Notch信号通路促进内皮细胞和血管之间的通讯 平滑肌细胞(VSMCs)。我们发现Jag1和Notch3在T2 DM(db/db)小鼠CRM中的表达是 缺乏EC表达的Jag1或Notch3缺失的小鼠的CBF受损程度类似于T2 DM (db/db)小鼠。此外，EC-Jag1缺陷小鼠有内向CRM重塑的证据。此外，我们 在糖尿病小鼠和猪的CRM中，以及EC-Jag1-Jag1中，Fenestrie显著减少。 缺陷小鼠，提示异细胞EC-VSMC在肌内皮细胞连接(MEJ)上的通讯 也许在所有型号中都会被颠覆。我们最近的研究发现Notch3和Jag1在正常CRM的MEJ上。 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 是由ECs和VSMC之间受损的Jag1/Notch信号驱动的。我们将使用一个 综合方法，结合遗传缺陷小鼠模型，EC-VSMC共培养技术，单一 细胞转录学和转基因/药物挽救实验：具体目标是：Aim1。检验假设 T2 DM导致CRM中Jag1/Notch信号的中断，并定义了这一机制。目标2.确定 如果Jag1/Notch信号异常有助于T2 DM患者不利的冠状动脉微血管重构 遗传学和转录学方法。目的3.验证Jag1/Notch信号激活可以 预防和/或治疗T2 DM诱导的冠状动脉微血管重构。这些研究将是第一次 证明Notch信号在CRM重塑和CBF受损中起中心作用，以及该通路的纠正 可能逆转T2 DM患者不良的CRM重构和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.