AP2σ Mutations Impair Calcium-Sensing Receptor Trafficking and Signaling, and Show an Endosomal Pathway to Spatially Direct G-Protein Selectivity

Caroline M Gorvin; Angela Rogers; Benoit Hastoy; Andrei I Tarasov; Morten Frost; Silvia Sposini; Asuka Inoue; Michael P Whyte; Patrik Rorsman; Aylin C Hanyaloglu; Gerda E Breitwieser; Rajesh V Thakker

doi:10.1016/j.celrep.2017.12.089

AP2σ Mutations Impair Calcium-Sensing Receptor Trafficking and Signaling, and Show an Endosomal Pathway to Spatially Direct G-Protein Selectivity

Cell Rep. 2018 Jan 23;22(4):1054-1066. doi: 10.1016/j.celrep.2017.12.089. Epub 2018 Jan 28.

Authors

Affiliations

¹ Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK; Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham, UK.
² Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
³ Diabetes Research Laboratory, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
⁴ Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, London, UK.
⁵ Laboratory of Molecular and Cellular Biochemistry, Tohoku University, Sendai, Japan; Japan Science and Technology (JST) Agency, Precursory Research for Embryonic Science and Technology (PRESTO), Kawaguchi, Japan.
⁶ Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, MO, USA.
⁷ Geisinger Clinic, Weis Center for Research, Department of Functional and Molecular Genomics, Danville, PA, USA.
⁸ Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK. Electronic address: rajesh.thakker@ndm.ox.ac.uk.

Abstract

Spatial control of G-protein-coupled receptor (GPCR) signaling, which is used by cells to translate complex information into distinct downstream responses, is achieved by using plasma membrane (PM) and endocytic-derived signaling pathways. The roles of the endomembrane in regulating such pleiotropic signaling via multiple G-protein pathways remain unknown. Here, we investigated the effects of disease-causing mutations of the adaptor protein-2σ subunit (AP2σ) on signaling by the class C GPCR calcium-sensing receptor (CaSR). These AP2σ mutations increase CaSR PM expression yet paradoxically reduce CaSR signaling. Hypercalcemia-associated AP2σ mutations reduced CaSR signaling via Gα_q/11 and Gα_i/o pathways. The mutations also delayed CaSR internalization due to prolonged residency time of CaSR in clathrin structures that impaired or abolished endosomal signaling, which was predominantly mediated by Gα_q/11. Thus, compartmental bias for CaSR-mediated Gα_q/11 endomembrane signaling provides a mechanistic basis for multidimensional GPCR signaling.

Keywords: G proteins; GPCR; adaptor protein-2; calcium signaling; clathrin-mediated endocytosis; endosomal signaling; hypercalcemia.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adaptor Protein Complex 2 / genetics*
Adaptor Protein Complex alpha Subunits / genetics*
Calcium Signaling / genetics*
Endosomes / metabolism*
GTP-Binding Proteins / metabolism*
Humans
Mutation
Receptors, Calcium-Sensing / genetics*

Substances

AP2A1 protein, human
Adaptor Protein Complex 2
Adaptor Protein Complex alpha Subunits
Receptors, Calcium-Sensing
GTP-Binding Proteins

Abstract

Publication types

MeSH terms

Substances

Grants and funding