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A Novel GLP1 Receptor Interacting Protein ATP6ap2 Regulates Insulin Secretion in Pancreatic Beta Cells
- Source :
- Journal of Biological Chemistry. 290:25045-25061
- Publication Year :
- 2015
- Publisher :
- Elsevier BV, 2015.
-
Abstract
- GLP1 activates its receptor, GLP1R, to enhance insulin secretion. The activation and transduction of GLP1R requires complex interactions with a host of accessory proteins, most of which remain largely unknown. In this study, we used membrane-based split ubiquitin yeast two-hybrid assays to identify novel GLP1R interactors in both mouse and human islets. Among these, ATP6ap2 (ATPase H(+)-transporting lysosomal accessory protein 2) was identified in both mouse and human islet screens. ATP6ap2 was shown to be abundant in islets including both alpha and beta cells. When GLP1R and ATP6ap2 were co-expressed in beta cells, GLP1R was shown to directly interact with ATP6ap2, as assessed by co-immunoprecipitation. In INS-1 cells, overexpression of ATP6ap2 did not affect insulin secretion; however, siRNA knockdown decreased both glucose-stimulated and GLP1-induced insulin secretion. Decreases in GLP1-induced insulin secretion were accompanied by attenuated GLP1 stimulated cAMP accumulation. Because ATP6ap2 is a subunit required for V-ATPase assembly of insulin granules, it has been reported to be involved in granule acidification. In accordance with this, we observed impaired insulin granule acidification upon ATP6ap2 knockdown but paradoxically increased proinsulin secretion. Importantly, as a GLP1R interactor, ATP6ap2 was required for GLP1-induced Ca(2+) influx, in part explaining decreased insulin secretion in ATP6ap2 knockdown cells. Taken together, our findings identify a group of proteins that interact with the GLP1R. We further show that one interactor, ATP6ap2, plays a novel dual role in beta cells, modulating both GLP1R signaling and insulin processing to affect insulin secretion.
- Subjects :
- Male
Vacuolar Proton-Translocating ATPases
medicine.medical_specialty
medicine.medical_treatment
Receptors, Cell Surface
CHO Cells
Biology
Biochemistry
Glucagon-Like Peptide-1 Receptor
Mice
Cricetulus
Glucagon-Like Peptide 1
Cricetinae
Insulin-Secreting Cells
Internal medicine
Insulin receptor substrate
Insulin Secretion
Cyclic AMP
medicine
Animals
Humans
Insulin
Secretion
Receptor
Molecular Biology
Proinsulin
ATP6AP2
Biological Transport
Cell Biology
Proton-Translocating ATPases
Insulin receptor
Endocrinology
Gene Knockdown Techniques
biology.protein
Calcium
Protein Binding
Insulin processing
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 290
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....cf37786eefe5fe6aa5588f551a7e9c8c