Dynamin function in beta cell autophagy

项目摘要 糖尿病影响着3000多万美国人，但其流行病仍在以惊人的速度上升。的 胰腺β细胞功能和质量的进行性下降是该疾病的标志，但没有 药物可以阻止这种下降。有趣的是，一种可以激活自噬的禁食模仿饮食 阻止了这种下降，它也逆转了小鼠的糖尿病。最近的进展越来越多地认识到， 自噬作为治疗糖尿病的潜在治疗靶点，因为自噬具有保护糖尿病的作用。 β细胞抵抗病原体和糖尿病应激。然而，β细胞自噬的基本性质 仍然知之甚少，特别是在控制自噬膜的分子过程中 裂变我们最近的数据显示，动力蛋白，一个已知调节 内吞作用和胰岛素分泌直接改变β细胞自噬。活细胞成像显示， 发动蛋白分子转移到自体溶酶体并驱动自体溶酶体分裂。条件动力蛋白 缺失导致β细胞中显著的自噬缺陷。这些新发现激发了人们对 了解在整个β细胞自噬周期中起作用的分子机制。我们 假设发动蛋白在β细胞自噬中起着直接和关键作用， 表征了从机制上讲，我们怀疑动力蛋白通过调节β细胞自噬来调节β细胞自噬。 自体溶酶体分裂和自噬运输。这些过程可能对保护β细胞至关重要 对抗慢性代谢压力我们组建了一个在β细胞生物学方面具有丰富专业知识的团队， 超分辨率成像、生化信号、小鼠遗传模型和糖尿病来测试这一点 假说.我们提出三个具体目标。首先，我们将明确发动蛋白在β细胞中的作用， 自体溶酶体分裂这个分裂步骤是必需的自体溶酶体到溶酶体的转化， 每一个自噬周期，但其机制仍然知之甚少。我们预计β细胞使用 在自噬中，发动蛋白将其自溶体分解成溶酶体。第二，我们将研究如何 发动蛋白调节β细胞微管以改变自噬转运。这些研究可能会揭示一个 以前未被重视的动力蛋白调节自噬的途径。第三，我们将检查发动机- 调节体内β细胞自噬。我们已经产生了发动蛋白异构体特异性小鼠模型。这些 独特的模型使得在体内评估动力蛋白调节的β细胞自噬及其 预防糖尿病的代谢应激。总之，这些研究将提供新的见解， 不同动力蛋白亚型介导的β细胞自噬的分子调控。其成果 将推进对β细胞自噬的基本理解， 和糖尿病发病机制。

PROJECT SUMMARY Diabetes affects over 30 million Americans, yet its epidemic is still rising at an alarming rate. The progressive decline of pancreatic β cell function and mass is a hallmark of the disease, but no medications prevent this decline. Interestingly, a fasting-mimicking diet known to activate autophagy stops this decline, and it also reverses diabetes in mice. Recent progress has increasingly recognized autophagy as a potential therapeutic target to treat diabetes because autophagy has a role in protecting β cells against pathogens and diabetic stress. However, the fundamental nature of β cell autophagy remains poorly understood, particularly in the molecular process governing autophagic membrane fission. Our recent data reveal that dynamin, a family of large GTPase proteins known to regulate endocytosis and insulin secretion, directly alters β cell autophagy. Live-cell imaging reveals that dynamin molecules translocate to autolysosomes and drive autolysosome fission. Conditional dynamin deletion causes striking autophagy defects in β cells. These new findings fuel tremendous interest in understanding the molecule mechanisms at play throughout the β cell autophagy cycle. We hypothesize that dynamin plays a direct and crucial role in β cell autophagy that has not been characterized. Mechanistically, we suspect that dynamin regulates β cell autophagy through regulating autolysosome fission and autophagic transport. These processes may be essential to protect β cells against chronic metabolic stress. We have assembled a team with substantial expertise in β cell biology, super-resolution imaging, biochemical signaling, mouse genetic models, and diabetes to test this hypothesis. We propose three specific aims. First, we will define the role of dynamin in β cell autolysosome fission. This fission step is necessary for autolysosome-to-lysosome transformation in each autophagic cycle, but its mechanism remains poorly understood. We expect that β cells use dynamin to resolve their autolysosomes into lysosomes in autophagy. Second, we will investigate how dynamin regulates β cell microtubules to alter autophagic transport. These studies may uncover a previously unappreciated pathway for dynamin to regulate autophagy. Third, we will examine dynamin- regulated β cell autophagy in vivo. We have generated dynamin isoform-specific mouse models. These unique models make it possible to evaluate dynamin-regulated β cell autophagy in vivo and its protection against the metabolic stress of diabetes. Together, these studies will provide new insight into the molecular regulation of β cell autophagy mediated by different dynamin isoforms. Their outcomes will advance the fundamental understanding of β cell autophagy that profoundly impacts islet function and diabetes pathogenesis.