Regulating SNARE mechanisms to remediate glucose homeostasis

2型糖尿病（T2 D）困扰着近10%的美国人口（约3000万人）; 令人震惊的是，还有8400万人患有前驱糖尿病，并显示出葡萄糖耐量受损的迹象。加上这个 问题，某些胰岛素增敏药物正在经历全球市场暂停，留下前驱糖尿病和 T2 D患者的治疗选择很少，迫切需要新的治疗方法。因为多- 组织功能障碍有助于前驱糖尿病和进展为T2 D，预防或逆转这些疾病 需要多管齐下。具体而言，胰腺β细胞功能障碍和骨骼肌（skm）胰岛素 耐药性是人类前驱糖尿病和T2 D的主要特征。STX 4，SNARE的主要组成部分 在来自患有T2 D的人的β-细胞和皮肤中，胞吐机制减少。此外，需要STX 4 小鼠模型和人胰岛中正常的β细胞胰岛素分泌和skm胰岛素敏感性。我们的长期 目的是了解β细胞和skm信号传导如何被操纵以预防或逆转前驱糖尿病， 阻止发展为T2 D。我们的中心假设是STX 4富集支持β细胞和/或骨骼肌细胞增殖。 肌肉，以防止和逆转糖尿病应激的破坏性影响。建议的理由 研究表明，一旦STX 4的这些新机制被阐明，STX 4信号传导可以被操纵， 预防或逆转T2 D。在上一个资助周期中，我们揭示了STX 4在促进β细胞增殖中的新作用。 生存和skm功能。事实上，在这些组织中过表达STX 4的小鼠具有显著的33%的 延长寿命，并保护免受衰老和饮食诱导的代谢功能障碍。同时，我们还发现， STX 4可以逆转肥胖小鼠的胰岛素抵抗。然而，STX 4的组织特异性作用尚不清楚。 因此，我们也产生了可诱导的β细胞和皮肤特异性STX 4过表达和敲除小鼠， 作为组织特异性STX 4富集的基于RNA的候选治疗剂。我们挑衅性的新初步调查 数据表明，STX 4参与β细胞中的抗炎信号传导，并定位于细胞外膜。 线粒体膜调节skm中线粒体功能。因此，本申请的目的 目的是测试这些将STX 4富集与β细胞和皮肤的保护联系起来的候选机制， 致糖尿病应激和评估候选STX 4富集治疗剂。我们将用我们的诱导型小鼠 用于这些研究的模型和人体组织/细胞。在目标1中，我们将评估 STX 4在β细胞中的保护作用，并测试新的β细胞STX 4富集策略;在目标2中，我们将 描述STX 4富集如何保护皮肤以及如何逆转HFD诱导的功能障碍。我们将使用 创新的分子工具，以测试新的假设STX 4行动的背景下， 希望之城的制度环境这项工作将积极影响糖尿病研究通过评估一个 有希望的候选策略，以逆转前驱糖尿病和阻止进展为T2 D，并通过发现新的 血糖调节机制。

Project Summary - Type 2 diabetes (T2D) plagues nearly 10% of the US population (~30 million people); a shocking 84 million more have prediabetes and show signs of impaired glucose tolerance. Compounding this problem, certain insulin-sensitizing drugs are undergoing global market suspensions, leaving prediabetic and T2D patients with few treatment options and creating an urgent need for new therapeutics. Because multi- tissue dysfunction contributes to prediabetes and progression to T2D, prevention or reversal of these diseases requires a multi-pronged approach. Specifically, pancreatic β-cell dysfunction and skeletal muscle (skm) insulin resistance are primary features of human prediabetes and T2D. STX4, a primary component of the SNARE exocytosis machinery, is reduced in β-cells and skm from humans with T2D. Furthermore, STX4 is required for normal β-cell insulin secretion and skm insulin sensitivity in mouse models and human islets. Our long-term goal is to understand how β-cell and skm signaling can be manipulated to prevent or reverse prediabetes and halt the progression to T2D. Our central hypothesis is that STX4 enrichment supports β-cells and/or skeletal muscle to prevent and reverse the damaging effects of diabetogenic stress. The rationale for the proposed research is that once these new mechanisms of STX4 are elucidated, STX4 signaling can be manipulated to prevent or reverse T2D. During the last funding cycle, we revealed new roles for STX4 in promoting β-cell survival and skm function. Indeed, mice overexpressing STX4 in these tissues have a remarkable 33% extended lifespan and are protected from aging- and diet-induced metabolic dysfunction. Also, we showed that STX4 can reverse insulin resistance in obese mice. However, the tissue-specific role of STX4 was unknown. Therefore, we generated inducible β-cell- and skm- specific STX4 overexpression and knockout mice, as well as RNA-based candidate therapeutics for tissue-specific STX4 enrichment. Our provocative new preliminary data indicate that STX4 participates in anti-inflammatory signaling in the β-cells, and localizes to the outer mitochondrial membrane to regulate mitochondrial function in skm. Therefore, the objective of this application is to test these candidate mechanisms linking STX4 enrichment and protection of β-cells and skm from diabetogenic stress and to evaluate candidate STX4 enrichment therapeutics. We will use our inducible mouse models and human tissues/cells for these studies. In Aim 1, we will evaluate the mechanisms underlying the protective actions of STX4 in β-cells and test novel β-cell STX4 enrichment strategies; in Aim 2, we will delineate how STX4 enrichment protects skm and how it reverses HFD-induced dysfunction. We will use innovative molecular tools to test novel hypotheses about STX4 action in the context of a translation-focused institutional environment at City of Hope. This work will positively impact diabetes research by evaluating a promising candidate strategy to reverse prediabetes and halt progression to T2D and by uncovering novel mechanisms of glycemic regulation.