PITPNA in pancreatic beta-cell dysfunction and diabetes pathogenesis

PITPNA 在胰腺 β 细胞功能障碍和糖尿病发病机制中的作用

• 批准号: 10636228
• 负责人: Matthew Ng Poy
• 金额: $ 41.56万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2027-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10636228
• 关键词: 1-Phosphatidylinositol 4-Kinase; Beta Cell; Cell Death; Cell Fractionation; Cell membrane; Cell physiology; Cells; Chronic; Cytoplasmic Granules; Data; Defect; Development; Diabetes Mellitus; Docking; Endoplasmic Reticulum; Exocytosis; Failure; Functional disorder; Heat shock proteins; Human; Hyperglycemia; Impairment; Individual; Insulin; Insulin Resistance; Intracellular Membranes; Islets of Langerhans; Link; LoxP-flanked allele; Membrane; Methods; Mitochondria; Morphology; Mus; Non-Insulin-Dependent Diabetes Mellitus; Oxidative Stress; Pancreas; Pathway interactions; Phosphatidylinositol Transfer Protein; Phosphatidylinositols; Phospholipids; Phosphorylation; Production; Proinsulin; Role; Secretory Vesicles; Structure of beta Cell of islet; Testing; diabetes pathogenesis; endoplasmic reticulum stress; human subject; improved; innovation; insulin granule; insulin secretion; islet; knock-down; mitochondrial dysfunction; mitochondrial membrane; novel strategies; pharmacologic; phosphatidylinositol 4-phosphate; prevent; restoration; trans-Golgi Network

PROJECT SUMMARY Critical to successful innovation in treating diabetes is the development of strategies for promoting insulin release and preventing pancreatic beta-cell destruction. Chronic demand for insulin production during insulin resistance and diabetes exacerbates cell dysfunction and this is compounded by ER and oxidative stress. This results in beta-cell death and loss of insulin production. Recent studies have highlighted defects in insulin processing, insulin granule maturation, and granule docking that are also linked to all major forms of diabetes; however conceptual gaps remain in understanding the causes of beta-cell failure and developing methods to reverse or prevent beta-cell dysfunction. Our preliminary studies establish Phosphatidylinositol transfer protein alpha (referred to as human PITPNA and mouse Pitpna), as a major regulator of insulin granule formation and secretion. PITPNA shuttles phosphatidylinositol (PI) from the endoplasmic reticulum (ER) to the trans-Golgi network (TGN) for phosphorylation by Phosphatidylinositol 4-kinase (PI4-K) conversion to phosphatidylinositol-4 phosphate (PtdIns-4-P), an abundant membrane phospholipid involved in insulin granule docking and exocytosis. Our preliminary data shows: 1) PITPNA expression is dramatically silenced in beta-cells of human T2D subjects, 2) reduction of PITPNA in human islets both lowered cellular PI4-P levels and insulin granule maturation and increased accumulation of proinsulin, and 3) conditional beta-cell specific deletion of Pitpna in mice (Ins-Cre; Pitpnaflox/flox) results in decreased insulin secretion and beta-cell mass, random-fed hyperglycemia, and increased expression of ER stress proteins in beta cells. Based on these data, we hypothesize that decreased PITPNA in beta-cells during T2D leads to lower PI4-P for distribution by the TGN as well as incorporation into insulin granules, thereby disrupting granule maturation, docking and secretion. We further hypothesize the reduced granule formation results in accumulation of proinsulin in the ER, leading to ER stress and ultimately beta-cell death. We propose that restoration of PITPNA in beta-cells of T2D individuals will reverse these aspects of cellular dysfunction. We expect these studies will demonstrate that promoting PITPNA function and PI4-P formation is a novel strategy for reversing beta-cell dysfunction in several subcellular compartments including the ER, mitochondria, and the TGN. These studies aim to highlight restoration of PI4-P between intracellular membranes as an innovative approach for increasing granule maturation and secretion as well as reversing beta-cell failure in major forms of diabetes.

项目概要 糖尿病治疗创新成功的关键是制定促进胰岛素的策略 释放并防止胰腺β细胞破坏。胰岛素注射期间对胰岛素产生的长期需求 抵抗力和糖尿病会加剧细胞功能障碍，而内质网和氧化应激会加剧这种情况。这 导致β细胞死亡和胰岛素产生丧失。最近的研究强调了胰岛素的缺陷 加工、胰岛素颗粒成熟和颗粒对接也与所有主要形式的糖尿病有关； 然而，在理解 β 细胞衰竭的原因和开发治疗方法方面仍存在概念上的差距。 逆转或预防β细胞功能障碍。 我们的初步研究建立了磷脂酰肌醇转移蛋白α（简称人 PITPNA 和小鼠 Pitpna)，作为胰岛素颗粒形成和分泌的主要调节剂。 PITPNA 班车 磷脂酰肌醇 (PI) 从内质网 (ER) 到反式高尔基体网络 (TGN) 磷脂酰肌醇 4-激酶 (PI4-K) 磷酸化转化为磷脂酰肌醇 4 磷酸 (PtdIns-4-P)，一种丰富的膜磷脂，参与胰岛素颗粒对接和胞吐作用。我们的 初步数据显示：1) PITPNA 表达在人类 T2D 受试者的 β 细胞中显着沉默，2) 人胰岛中 PITPNA 的减少会降低细胞 PI4-P 水平和胰岛素颗粒成熟度， 胰岛素原积累增加，以及 3) 小鼠条件性 β 细胞特异性删除 Pitpna (Ins-Cre； Pitpnaflox/flox）导致胰岛素分泌和β细胞质量减少、随机喂养高血糖以及增加 β细胞中ER应激蛋白的表达。 基于这些数据，我们假设 T2D 期间 β 细胞中 PITPNA 的减少导致 PI4-P 通过 TGN 进行分配并掺入胰岛素颗粒中，从而破坏颗粒 成熟、对接和分泌。我们进一步假设颗粒形成的减少导致积累 内质网中胰岛素原的含量增加，导致内质网应激并最终导致β细胞死亡。我们建议恢复 T2D 个体 β 细胞中的 PITPNA 将逆转细胞功能障碍的这些方面。我们期待这些 研究将证明促进 PITPNA 功能和 PI4-P 形成是逆转 PITPNA 功能和 PI4-P 形成的新策略 包括 ER、线粒体和 TGN 在内的多个亚细胞区室中的 β 细胞功能障碍。这些 研究旨在强调细胞内膜之间 PI4-P 的修复作为一种创新方法 增加颗粒的成熟和分泌，并逆转主要糖尿病形式的β细胞衰竭。