Cytoskeleton-mediated regulation of insulin secretion hot spots in pancreatic beta cells

项目摘要 胰腺β细胞的胰岛素分泌对维持血糖稳态至关重要， 从血液中摄取葡萄糖并获得正常细胞过程所需的营养物质。在 然而，2型糖尿病，外周组织变得胰岛素抵抗，β细胞过度分泌胰岛素， 补偿，最终β细胞变得功能失调。因此，有必要彻底了解 胰岛素分泌的机制，以确定2型糖尿病的潜在治疗靶点 治疗已知胰岛素分泌主要发生在β细胞的血管面，在区域 称为“热点”。热点的特点是蛋白质共同的活动区的神经元以及 皮质微管稳定复合物和局灶性粘连蛋白。我们的实验室还发现， 微管不稳定促进胰岛素分泌，特别是在热点。其他研究表明， 肌动蛋白细胞骨架在胰岛素分泌中也起关键的调节作用。鉴于已知的 微管，粘着斑和肌动蛋白与已知的热点蛋白质，很可能是这些相互作用 细胞骨架元件对于热点组织和功能是必不可少的。因此我假设胰岛素 分泌热点是“分泌粘连”：机械敏感的亚细胞结构域， 调节以实现定向和聚集分泌。我的具体目标是1）描述 细胞骨架网络，它们的相互作用，以及β细胞中的其他热点成分;以及2）测试MT- 调节RhoA依赖性收缩性通过分泌粘附促进聚集分泌 组装件.为了实现这些目标，我将使用高分辨率和超分辨率的固定细胞和活细胞成像技术 结合计算分析。通过以下方式提高对热点识别和建立的认识 细胞骨架将有助于全面了解胰岛素分泌，并有可能发现新的靶点 用于糖尿病治疗。

Project Summary Insulin secretion from pancreatic β cells is crucial to maintaining blood glucose homeostasis, allowing cells throughout the body to take up glucose from the blood and obtain nutrients for normal cellular processes. In type 2 diabetes, however, peripheral tissues become insulin resistant, β cells over-secrete insulin to compensate, and eventually β cells become dysfunctional. It is therefore necessary to thoroughly understand the mechanisms of insulin secretion in order to identify potential therapeutic targets for type 2 diabetes treatment. Insulin secretion is known to predominantly occur at the vascular face of the β cell, at regions termed “hot spots.” Hot spots are characterized by proteins common to the active zone of neurons as well as proteins of cortical microtubule-stabilizing complexes and focal adhesions. Our laboratory has also found that microtubule destabilization promotes insulin secretion specifically at hot spots. Others have shown that the actin cytoskeleton also plays a critical regulatory role in insulin secretion. Given the known connections of microtubules, focal adhesions, and actin with known hot spot proteins, it is likely that the interplay of these cytoskeletal elements is essential for the hot spot organization and function. I therefore hypothesize that insulin secretion hot spots are “secreting adhesions”: mechanosensitive subcellular domains which use cytoskeletal regulation to accomplish directed and clustered secretion. My specific aims are to 1) characterize the cytoskeleton networks, their interplay, and other hot spot components in β cells; and to 2) test if MT- regulated RhoA-dependent contractility promotes clustered secretion via secreting adhesion assembly. To address these aims, I will use high- and super-resolution fixed and live-cell imaging techniques combined with computational analyses. Improving the understanding of hot spot identity and establishment via the cytoskeleton will contribute to overall knowledge of insulin secretion, and potentially uncover novel targets for diabetes therapeutics.