Dataset Information

Ligand-Specific Factors Influencing GLP-1 Receptor Post-Endocytic Trafficking and Degradation in Pancreatic Beta Cells.

ABSTRACT: The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of blood glucose homeostasis. Ligand-specific differences in membrane trafficking of the GLP-1R influence its signalling properties and therapeutic potential in type 2 diabetes. Here, we have evaluated how different factors combine to control the post-endocytic trafficking of GLP-1R to recycling versus degradative pathways. Experiments were performed in primary islet cells, INS-1 832/3 clonal beta cells and HEK293 cells, using biorthogonal labelling of GLP-1R to determine its localisation and degradation after treatment with GLP-1, exendin-4 and several further GLP-1R agonist peptides. We also characterised the effect of a rare GLP1R coding variant, T149M, and the role of endosomal peptidase endothelin-converting enzyme-1 (ECE-1), in GLP1R trafficking. Our data reveal how treatment with GLP-1 versus exendin-4 is associated with preferential GLP-1R targeting towards a recycling pathway. GLP-1, but not exendin-4, is a substrate for ECE-1, and the resultant propensity to intra-endosomal degradation, in conjunction with differences in binding affinity, contributes to alterations in GLP-1R trafficking behaviours and degradation. The T149M GLP-1R variant shows reduced signalling and internalisation responses, which is likely to be due to disruption of the cytoplasmic region that couples to intracellular effectors. These observations provide insights into how ligand- and genotype-specific factors can influence GLP-1R trafficking.

SUBMITTER: Fang Z

PROVIDER: S-EPMC7664906 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Publications

Ligand-Specific Factors Influencing GLP-1 Receptor Post-Endocytic Trafficking and Degradation in Pancreatic Beta Cells.

Fang Zijian Z Chen Shiqian S Manchanda Yusman Y Bitsi Stavroula S Pickford Philip P David Alessia A Shchepinova Maria M MM Corrêa Ivan R IR Hodson David J DJ Broichhagen Johannes J Tate Edward W EW Reimann Frank F Salem Victoria V Rutter Guy A GA Tan Tricia T Bloom Stephen R SR Tomas Alejandra A Jones Ben B

International journal of molecular sciences 20201109 21

The glucagon-like peptide-1 receptor (GLP-1R) is an important regulator of blood glucose homeostasis. Ligand-specific differences in membrane trafficking of the GLP-1R influence its signalling properties and therapeutic potential in type 2 diabetes. Here, we have evaluated how different factors combine to control the post-endocytic trafficking of GLP-1R to recycling versus degradative pathways. Experiments were performed in primary islet cells, INS-1 832/3 clonal beta cells and HEK293 cells, usi ...[more]

PMID: 33182425

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Project description:Pancreatic β-cells have the key homeostatic function of releasing insulin to keep blood glucose in the normal range. It is not fully understood how β-cell mass is determined. Ablation of a nuclear receptor, chicken ovalbumin upstream promoter transcription factor II (COUP-TFII), in mouse pancreatic β-cells results in glucose intolerance and 50% fewer β-cells during the postnatal period. By testing islets isolated from these mice and cultured β-cells with loss and gain of COUP-TFII function, we found that COUP-TFII induces β-catenin thus upregulating target genes like cyclin D1. Beta-cell expansion triggered by glucagon-like peptide 1 (GLP-1) is known to be mediated by β-catenin controlling cyclin D1. We show that in the absence of COUP-TFII, exendin-4, an agonist of the GLP-1 receptor, does not fully induce cyclin D1 expression, while overexpression of β-catenin induces cyclin D1. A marked decrease in cyclin D1 expression is detected in islets isolated from transgenic mice lacking both GLP-1 receptor and gastric inhibitory peptide receptor. COUP-TFII is therefore required for GLP-1 activation of the β-catenin-dependent pathway in pancreatic β-cells to increase β-cell number. To understand the molecular mechanisms by which COUP-TFII controls β-cell mass, we determined the RNA profile of COUP-TFII knockdown β-cells using Affymetrix oligonucleotide microarrays. Computational analysis identified clusters of genes shared by different gene regulatory Networks that are up or down regulated namely genes involved in Wnt/β-catenin signaling, insulin signaling and lipid/carbohydrate metabolism. We determined the RNA profile of COUP-TFII knockdown β-cells (832/13 INS-1 cells transfected with COUP-TFII specific siRNA) with respect to control cells (832/13 INS-1 cells transfected with scrambled siRNA) using Affymetrix expression analysis technical manual 701025Rev.5 (Affymetrix, Santa Clara, California, USA). Briefly, 1 mg of total cellular mRNA was reverse transcribed into cDNA (SuperScript Choice System Invitrogen, Carlsbad, CA) using oligo-dT primers and a T7 RNA polymerase promoter site. The cDNA was in vitro transcribed and biotin-labeled for microarray analysis using the Affymetrix IVT labeling kit. The concentration of labelled cRNA was measured using a NanoDrop ND-1000 spectrophotometer. Labeled cRNA was fragmented in a fragmentation buffer for 35 min at 94°C. The quality of labeled and fragmented cRNA was analyzed using the Agilent bioanalyzer 2100 (Van Lommel et al, 2006). Fragmented cRNA was hybridized to the rat 230 2.0 array (Affymetrix) during 16h at 45°C. Arrays were washed and stained in a fluidics station (Affymetrix) and scanned using the Affymetrix 3000 GeneScanner.

Dataset Information

Ligand-Specific Factors Influencing GLP-1 Receptor Post-Endocytic Trafficking and Degradation in Pancreatic Beta Cells.

Publications

Ligand-Specific Factors Influencing GLP-1 Receptor Post-Endocytic Trafficking and Degradation in Pancreatic Beta Cells.

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