Orai1 mediates the interaction between STIM1 and hTRPC1 and regulates the mode of activation of hTRPC1-forming Ca2+ channels.
Orai1 and hTRPC1 have been presented as essential components of store-operated channels mediating highly Ca(2+) selective I(CRAC) and relatively Ca(2+) selective I(SOC), respectively. STIM1 has been proposed to communicate the Ca(2+) content of the intracellular Ca(2+) stores to the plasma membrane store-operated Ca(2+) channels. Here we present evidence for the dynamic interaction between endogenously expressed Orai1 and both STIM1 and hTRPC1 regulated by depletion of the intracellular Ca(2+) stores, using the pharmacological tools thapsigargin plus ionomycin, or by the physiological agonist thrombin, independently of extracellular Ca(2+). In addition we report that Orai1 mediates the communication between STIM1 and hTRPC1, which is essential for the mode of activation of hTRPC1-forming Ca(2+) permeable channels. Electrotransjection of cells with anti-Orai1 antibody, directed toward the C-terminal region that mediates the interaction with STIM1, and stabilization of an actin cortical barrier with jasplakinolide prevented the interaction between STIM1 and hTRPC1. Under these conditions hTRPC1 was no longer involved in store-operated calcium entry but in diacylglycerol-activated non-capacitative Ca(2+) entry. These findings support the functional role of the STIM1-Orai1-hTRPC1 complex in the activation of store-operated Ca(2+) entry.
Jardin
Isaac
I
Department of Physiology, Cellular Physiology Research Group, University of Extremadura, 10071 Caceres, Spain.
Lopez
José J
JJ
Department of Physiology, Cellular Physiology Research Group, University of Extremadura, 10071 Caceres, Spain.
Salido
Gines M
GM
Department of Physiology, Cellular Physiology Research Group, University of Extremadura, 10071 Caceres, Spain.
Rosado
Juan A
JA
Department of Physiology, Cellular Physiology Research Group, University of Extremadura, 10071 Caceres, Spain. Electronic address: jarosado@unex.es.
D001792:Blood Platelets / Q000378:metabolism; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival; D047630:Depsipeptides / Q000494:pharmacology; D004075:Diglycerides / Q000737:chemistry; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000378:metabolism*; D000071740:ORAI1 Protein; D017434:Protein Structure, Tertiary; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels / Q000378:metabolism*; D013917:Thrombin / Q000737:chemistry
D015220:Calcium Channels; D047630:Depsipeptides; D004075:Diglycerides; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1; C057531:jasplakinolide; D015759:Ionomycin; D013917:Thrombin; D002118:Calcium