Secretory Pathway Protein Degradation Maintains Insulin Biogenesis + Secretion

分泌途径蛋白质降解维持胰岛素生物合成分泌

基本信息

批准号：
10217112
负责人：
PETER ARVAN
金额：
$ 63.69万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2016
资助国家：
美国
起止时间：
2016-07-15 至 2025-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10217112
关键词：
Anabolism Animals Area Autophagocytosis Bacteriophages Belief Beta Cell Biogenesis Biological Blood Glucose Cell physiology Cells Complex Coupled Data Defect Degradation Pathway Development Diabetes Mellitus Disease Disease Progression Distal Endoplasmic Reticulum Endoplasmic Reticulum Degradation Pathway Ensure Failure Functional disorder Genes Genetic Glucose Golgi Apparatus Grant Homeostasis Hormones Human Hyperactivity INS gene Insulin Insulin deficiency Knockout Mice Lead Link Lysosomes Maintenance Membrane Messenger RNA Mind Modeling Molecular Mus Non-Insulin-Dependent Diabetes Mellitus Pathway interactions Patients Peptide Signal Sequences Phenotype Predisposition Process Production Proinsulin Proteins Qi Quality Control Research Research Personnel Role Route Secretory Cell Secretory Vesicles Site Structure of beta Cell of islet TGF Beta Signaling Pathway Therapeutic Translations Vesicle Work Youth anterograde transport base biological adaptation to stress dalton diabetes pathogenesis diabetes risk endoplasmic reticulum stress follow-up islet mutant non-diabetic novel therapeutic intervention preproinsulin prevent protein degradation recruit risk variant secretory protein signal sequence receptor success transcription factor transcriptomics

项目摘要

Pancreatic beta-cells synthesize large quantities of insulin. Growing evidence indicates that any of a number of deficiencies in insulin biosynthesis (genetic, or acquired) can lead to diabetes. We know that insulin biosynthesis begins with translation of preproinsulin. This short-lived precursor must be translocated into the endoplasmic reticulum (ER), signal peptide excised, and proinsulin properly folded in order to undergo successful export from the ER for delivery to the distal secretory pathway in which proinsulin-to-insulin processing and insulin storage in secretory granules finally occurs. In contrast, unsuccessful molecules may be degraded before they are even translocated into the ER, or may be restrained from anterograde export from the ER — indeed, strong evidence indicates that misfolded proinsulin molecules are targeted for degradation. Secretory pathway protein degradation also involves other endogenous substrates that contribute to the differentiated pancreatic beta cell phenotype. The competing continuation of this multi-P.I. R01 will help clarify how three major mechanisms of secretory pathway protein disposal – pre-translocation degradation; ER-Associated Degradation (ERAD); and Autophagy – are all critical for proper beta-cell function. This proposal continues the longstanding association of three tightly collaborative investigators (Qi, Tsai, Arvan) that are experts in exactly these processes: preproinsulin translocation into the ER lumen with the subsequent folding/misfolding of proinsulin, secretory pathway protein degradation via ERAD, and an ER-to-lysosome degradative pathway that we believe is primarily ER-autophagy (ER-phagy). We have strong reason to believe that defects in these quality control mechanisms are linked to type 2 diabetes (T2D) as a result of insulin insufficiency, and this belief is supported by preliminary data. In this proposal, we seek to examine three interlinked areas related to the early secretory pathway of pancreatic beta-cells. For one, we will pursue studies in which infidelity of preproinsulin translocation across the ER membrane is directly linked to deficient proinsulin and insulin biosynthesis, leading directly to diabetes. Second, we will follow-up on some remarkable preliminary data demonstrating that de-differentiation of pancreatic beta-cells is triggered by a loss of efficient ERAD function, also leading directly to insulin-deficient diabetes. Finally, we not only delve deeply into the ER factors that trigger ER-phagic degradation of misfolded proinsulin, but we also propose a deeper understanding of how ineffective or improper ER-phagy can trigger beta cell failure, which also leads directly to insulin-deficient diabetes. These new research directions lead us to pursue a novel therapeutic approach to beta-cell secretory pathway dysfunction focused on stimulating intracellular protein clearance mechanisms, in order to prevent diabetes onset and/or limit its progression.

越来越多的证据表明，胰岛素生物合成（遗传性或后天性）的任何缺陷都可能导致糖尿病。我们知道，胰岛素生物合成始于前胰岛素原的翻译。必须转位到内质网 (ER)、切除信号肽并正确折叠胰岛素原，才能成功从 ER 输出并输送到远端胰岛素原到胰岛素的加工和胰岛素在分泌颗粒中的储存最终发生在分泌途径中，相比之下，不成功的分子可能在转移到内质网之前就被降解，或者可能被限制从内质网顺行输出——实际上，很强烈。有证据表明，错误折叠的胰岛素原分子是降解的目标，还涉及其他有助于分化的胰腺β细胞表型的内源性底物。 multi-P.I. R01 将有助于阐明分泌途径蛋白质处置的三种主要机制——易位前降解（ERAD）；以及自噬——对于正常的 β 细胞功能至关重要。三位紧密合作的研究人员（Qi、Tsai、Arvan）正是这些过程的专家：前胰岛素原易位到 ER 腔中，随后折叠/错误折叠胰岛素原、通过 ERAD 的分泌途径蛋白降解以及我们认为主要是 ER 自噬 (ER-自噬) 的 ER 至溶酶体降解途径。我们有充分的理由相信这些质量控制机制中的缺陷与 2 型相关。糖尿病（T2D）是胰岛素不足的结果，这一观点得到了初步数据的支持。在本提案中，我们试图研究与胰腺早期分泌途径相关的三个相互关联的领域。首先，我们将开展研究，发现前胰岛素原跨内质网膜的不准确易位与胰岛素原和胰岛素生物合成缺陷直接相关，从而直接导致糖尿病；其次，我们将跟进一些显着的初步数据，证明这一点。胰腺β细胞的去分化是由有效的ERAD功能丧失引发的，也直接导致胰岛素缺乏型糖尿病。最后，我们不仅深入研究了引发ERAD的因素。错误折叠的胰岛素原的内质网吞噬降解，但我们还建议更深入地了解无效或不当的内质网吞噬如何引发β细胞衰竭，这也直接导致胰岛素缺乏型糖尿病。这些新的研究方向引导我们寻求一种新的治疗方法。治疗 β 细胞分泌途径功能障碍的方法侧重于刺激细胞内蛋白质清除机制，以预防糖尿病发作和/或限制其进展。