Store-operated Ca2+ Entry Mediated by Orai1 and TRPC1 Participates to Insulin Secretion in Rat β-Cells.
Store-operated Ca(2+) channels (SOCs) are voltage-independent Ca(2+) channels activated upon depletion of the endoplasmic reticulum Ca(2+) stores. Early studies suggest the contribution of such channels to Ca(2+) homeostasis in insulin-secreting pancreatic β-cells. However, their composition and contribution to glucose-stimulated insulin secretion (GSIS) remains unclear. In this study, endoplasmic reticulum Ca(2+) depletion triggered by acetylcholine (ACh) or thapsigargin stimulated the formation of a ternary complex composed of Orai1, TRPC1, and STIM1, the key proteins involved in the formation of SOCs. Ca(2+) imaging further revealed that Orai1 and TRPC1 are required to form functional SOCs and that these channels are activated by STIM1 in response to thapsigargin or ACh. Pharmacological SOCs inhibition or dominant negative blockade of Orai1 or TRPC1 using the specific pore mutants Orai1-E106D and TRPC1-F562A impaired GSIS in rat β-cells and fully blocked the potentiating effect of ACh on secretion. In contrast, pharmacological or dominant negative blockade of TRPC3 had no effect on extracellular Ca(2+) entry and GSIS. Finally, we observed that prolonged exposure to supraphysiological glucose concentration impaired SOCs function without altering the expression levels of STIM1, Orai1, and TRPC1. We conclude that Orai1 and TRPC1, which form SOCs regulated by STIM1, play a key role in the effect of ACh on GSIS, a process that may be impaired in type 2 diabetes.
From the INSERM, UMR S1180, Université Paris-Sud, Université Paris-Saclay, 92296 Châtenay-Malabry, France, jessica.sabourin@u-psud.fr.
Jessica
J
Sabourin
the Department of Medicine, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland, and.
Loïc
L
Le Gal
the Department of Medicine, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland, and.
Lisa
L
Saurwein
the Department of Medicine, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland, and.
Jacques-Antoine
JA
Haefliger
the Department of Physiology, University of Lausanne, 1005 Lausanne, Switzerland.
Eric
E
Raddatz
the Department of Medicine, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland, and.
Florent
F
Allagnat
D000109:Acetylcholine / Q000494:pharmacology; D019943:Amino Acid Substitution; D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling; D045744:Cell Line, Tumor; D007328:Insulin / Q000235:genetics / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D000071740:ORAI1 Protein; D051381:Rats; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels / Q000235:genetics / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology
D015220:Calcium Channels; D007328:Insulin; D008562:Membrane Glycoproteins; D000071740:ORAI1 Protein; C532493:Orai1 protein, rat; C518857:Stim1 protein, rat; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1; D019284:Thapsigargin; D000109:Acetylcholine; D002118:Calcium
beta cell (B-cell); calcium release-activated calcium channel protein 1 (ORAI1); insulin secretion; stromal interaction molecule 1 (STIM1); transient receptor potential channels (TRP channels)