Investigating the role of ER-phagy in proinsulin quality control

研究 ER 吞噬在胰岛素原质量控制中的作用

基本信息

批准号：
10676144
负责人：
Jeffrey Ryan Knupp
金额：
$ 4.24万
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：
2021
资助国家：
美国
起止时间：
2021-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10676144
关键词：
Alleles Anabolism Autophagocytosis Beta Cell Binding Biochemical Blood Glucose Cells Client Code Complex Coupled Cytosol Data Defect Detergents Diabetes Mellitus Disease Dominant-Negative Mutation Endoplasmic Reticulum Excision Failure Golgi Apparatus Health INS gene Impairment Insulin Insulin-Dependent Diabetes Mellitus Integral Membrane Protein Islets of Langerhans Link Lysosomes Mediating Membrane Membrane Proteins Metabolic syndrome Microscopy Modeling Molecular Molecular Chaperones Molecular Weight Mutagenesis Mutation N-terminal Pathway interactions Peptide Hydrolases Peptide Signal Sequences Physiological Process Production Proinsulin Proteins Quality Control Reporting Role Secretory Vesicles Structure of beta Cell of islet Syndrome Testing Therapeutic Toxic effect Up-Regulation Variant Youth blood glucose regulation combat diabetic early onset endoplasmic reticulum stress gain of function improved insight insulin secretion mutant novel novel therapeutic intervention pancreatic juice peptide hormone pharmacologic preproinsulin prevent protein aggregation receptor recruit uptake

项目摘要

Abstract Diabetes mellitus (DM) is a metabolic syndrome that is caused by deficiency in the secretion of insulin, which is a peptide hormone that is secreted by pancreatic β-cells to regulate the uptake of blood glucose. The insulin precursor proinsulin is folded in the β-cell endoplasmic reticulum (ER). When properly folded, proinsulin exits the ER and traffics to the Golgi and into secretory granules where it is proteolytically processed to form bioactive insulin, destined for secretion. Defects in this process can directly result in DM. This is exemplified during a condition called Mutant INS-gene-induced Diabetes Youth (MIDY), which is an early-onset diabetic condition caused by expression of a mutant proinsulin. MIDY mutant proinsulins exert a toxic gain-of-function on wildtype (WT) proinsulin folding and maturation because when they misfold, they form high-molecular weight, detergent-insoluble aggregates that also entrap WT proinsulin in the ER, thereby decreasing insulin secretion. Decreased insulin secretion results in compensatory upregulation in even more WT and mutant proinsulin, causing ER stress and β-cell demise. We have recently found that the ER-coupled autophagy (ER- phagy) pathway is required for degradation of MIDY proinsulin aggregates. This process depends on the ER- phagy receptor RTN3. Our unpublished findings now suggest that the ER membrane protein PGRMC1 is a RTN3-binding partner that functions as a cargo receptor to recruit MIDY proinsulin to RTN3 for disposal. PGRMC1 physically interacts with both RTN3 and mutant proinsulin, demonstrating that the PGRMC1-RTN3 complex acts as the nexus between MIDY proinsulin and the ER-phagy pathway. Strikingly, pharmacological impairment of PGRMC1 increases proinsulin secretion. We therefore hypothesize that PGRMC1 complexes with RTN3 to recruit mutant proinsulin into the ER-phagy pathway (Aim 1), and that impairing the RTN3- PGRMC1 complex triggers WT proinsulin secretion in physiologically important MIDY models (Aim 2).

抽象的糖尿病（DM）是一种代谢综合征，是由于胰岛素分泌缺乏引起的由胰腺β细胞分泌的肽马酮，以调节血糖的摄取。胰岛素前体蛋白折叠在β细胞内质网（ER）中。正确折叠时，Proinsulin退出急诊室和高尔基的流量，进入秘密颗粒，在该秘密颗粒中进行蛋白水解处理以形成生物活性胰岛素，注定要分泌。此过程中的缺陷可以直接导致DM。这是例证的在称为突变体INS基因诱导的糖尿病青年（MIDY）的情况下，这是一种早期发作的糖尿病由突变蛋白的表达引起的条件。 Midy突变蛋白发挥有毒的功能在野生型（wt）促硫蛋白折叠和成熟，因为当它们错误折叠时，它们会形成高分子重量，确定溶质骨料的不溶聚体，从而减少胰岛素分泌。胰岛素分泌减少导致更多的WT和突变体的补偿性上调促硫素，导致ER应力和β细胞灭亡。我们最近发现，ER耦合自噬（ER- 中质硫素聚集体降解需要吞噬）途径。这个过程取决于ER- PHAGY接收器RTN3。我们未发表的发现现在表明ER膜蛋白PGRMC1是一个 RTN3结合合作伙伴是载有Midy Proinsulin到RTN3处置的货物接收器的合作伙伴。 PGRMC1与rtn3和突变蛋白都有物理相互作用，表明PGRMC1-RTN3 复合物充当Midy Proinsulin和ER-Phagy途径之间的下一个。令人惊讶的是，药物 PGRMC1的损害增加了促硫素的分泌。因此，我们假设PGRMC1配合物使用RTN3将突变蛋白募集到ER-PHAGY途径中（AIM 1），并损害RTN3- PGRMC1复合物在物理上重要的MIDY模型中触发WT Proinsulin分泌（AIM 2）。