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Endosomal regulation of GLP-1 receptor function in beta cells by Clec16a

Clec16a 对 β 细胞中 GLP-1 受体功能的内体调节

基本信息

批准号：
8949507
负责人：
Scott Soleimanpour
金额：
$ 7.75万
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：
2015
资助国家：
美国
起止时间：
2015-07-01 至 2017-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8949507
关键词：
Acute Agonist Alleles Autophagocytosis Beta Cell Biological Assay CREB1 gene Cell Line Cell Proliferation Cell physiology Cells Confocal Microscopy Cyclic AMP Cyclic AMP-Dependent Protein Kinases Data Diabetes Mellitus Endocytosis Endosomes Evaluation G-Protein-Coupled Receptors GCG gene Generations Genes Genetic Polymorphism Glucose Glucose Intolerance Goals Human Insulin Knock-out Label Life Ligand Binding Ligands Liquid substance Lysosomes Mediating Methods Mission Modeling Molecular Mus Outcome Pancreas Pathway interactions Patients Pharmaceutical Preparations Phase Phosphorylation Phosphorylation Site Physiologic pulse Physiological Play Post-Translational Protein Processing Proteins Receptor Signaling Regulation Research Role Signal Transduction Site-Directed Mutagenesis Testing Therapeutic Agents Tracer Work base blood glucose regulation cellular imaging diabetic patient exenatide glucagon-like peptide glucagon-like peptide 1 glucose tolerance improved improved functioning in vivo insulin secretion islet loss of function migration mouse model public health relevance receptor receptor function research study response trafficking uptake

项目摘要

DESCRIPTION (provided by applicant): The research proposed in this R03 application will focus on the endosomal turnover of the glucagon- like peptide 1 receptor (GLP1R), a G-protein coupled receptor, in pancreatic ß-cells by the endolysosomal protein Clec16a. GLP1R agonists are valuable therapeutic agents for diabetes based upon their direct effects on ß-cells; however, these effects are often self-limited by mechanisms to inactivate GLP1R-dependent signaling. Strategies to slow endolysosomal turnover of ligand bound GLP1Rs could therefore be beneficial to extend the activity of GLP1R agonists. Clec16a has been previously shown to be a key regulator of autophagy in ß-cells, but endolysosomal proteins can often play complementary roles in both autophagy and endosomal trafficking. Indeed, our preliminary studies reveal that Clec16a regulates trafficking of endocytic fluid-phase tracers in pancreatic ß-cells and is also phosphorylated by protein kinase A (PKA) in response to GLP1R agonist treatment. Furthermore, we find that acute treatment with GLP1R agonists markedly enhances insulin release in pancreas-specific Clec16a knockout islets. Therefore, we hypothesize that Clec16a negatively regulates GLP1R signaling through a direct role in the endolysosomal degradation of ligand bound GLP1 receptors. Specific Aim I. Determine the physiologic impact of loss of Clec16a on GLP1R signaling in vivo. This aim will utilize ß-cell specific loss-of-function experiments in vivo using a conditional Clec16a loxP allele, as well as in isolated islets, following treatment with GLP1R-agonists. Experiments will focus on determinations of glucose tolerance and insulin secretion, as well as morphologic analysis of ß-cell mass related to changes in ß-cell proliferation and/or survival. Specific Aim II. To investigate Clec16a-dependent regulation of GLP1R endolysosomal trafficking and degradation. Experiments will determine the role of Clec16a in turnover of ligand-bound GLP1Rs through the endolysosomal pathway by live cell imaging assays. In addition, the regulatory role of PKA-dependent phosphorylation of Clec16a to regulate trafficking/degradation of GLP1R at the lysosome will be determined. By completing the work described in these aims, we will establish the role and functional mechanism for GLP1R-degradation by Clec16a and the endolysosomal pathway. We will determine the utility of inhibition of the endosomal pathway to relieve the breaks on Ex-4 mediated signaling to improve ß-cell function, which could open a new pathway to enhance GLP1R-agonist therapy for patients with diabetes. Furthermore, these studies may suggest new GLP1-based approaches to treat diabetic patients with CLEC16A polymorphisms.