The calcium channel subunit gamma-4 is regulated by MafA and necessary for pancreatic beta-cell specification

• DOI: 10.1038/s42003-019-0351-4
• Publication Date: 2019-03-15T11:02:32Z
• Authors: Cheng Luan; Yingying Ye; Tania Singh; Mohammad Barghouth; Lena Eliasson; Isabella Artner; Enming Zhang; Erik Renström
• Keywords: Mice, Knockout; 0301 basic medicine; Maf Transcription Factors, Large; Gene Expression; Models, Biological; Article; Rats; Mice; 03 medical and health sciences; Calcium Channels, N-Type; Glucose; Gene Expression Regulation; Insulin-Secreting Cells; Insulin Secretion; Animals; Humans; Calcium; Calcium Signaling; Biomarkers

AbstractVoltage-gated Ca2+ (CaV) channels trigger glucose-induced insulin secretion in pancreatic beta-cell and their dysfunction increases diabetes risk. These heteromeric complexes include the main subunit alpha1, and the accessory ones, including subunit gamma that remains unexplored. Here, we demonstrate that CaV gamma subunit 4 (CaVγ4) is downregulated in islets from human donors with diabetes, diabetic Goto-Kakizaki (GK) rats, as well as under conditions of gluco-/lipotoxic stress. Reduction of CaVγ4 expression results in decreased expression of L-type CaV1.2 and CaV1.3, thereby suppressing voltage-gated Ca2+ entry and glucose stimulated insulin exocytosis. The most important finding is that CaVγ4 expression is controlled by the transcription factor responsible for beta-cell specification, MafA, as verified by chromatin immunoprecipitation and experiments in beta-cell specific MafA knockout mice (MafAΔβcell). Taken together, these findings suggest that CaVγ4 is necessary for maintaining a functional differentiated beta-cell phenotype. Treatment aiming at restoring CaVγ4 may help to restore beta-cell function in diabetes.