Lipid rafts are essential for the regulation of SOCE by plasma membrane resident STIM1 in human platelets.
STIM1 is a transmembrane protein essential for the activation of store-operated Ca²+ entry (SOCE), a major Ca²+ influx mechanism. STIM1 is either located in the endoplasmic reticulum, communicating the Ca²+ concentration in the stores to plasma membrane channels or in the plasma membrane, where it might sense the extracellular Ca²+ concentration. Plasma membrane-located STIM1 has been reported to mediate the SOCE sensitivity to extracellular Ca²+ through its interaction with Orai1. Here we show that plasma membrane lipid raft domains are essential for the regulation of SOCE by extracellular Ca²+. Treatment of platelets with the SERCA inhibitor thapsigargin (TG) induced Mn²+ entry, which was inhibited by increasing concentrations of extracellular Ca²+. Platelet treatment with methyl-β-cyclodextrin, which removes cholesterol and disrupts the lipid raft domains, impaired the inactivation of Ca²+ entry induced by extracellular Ca²+. Methyl-β-cyclodextrin also abolished translocation of STIM1 to the plasma membrane stimulated by treatment with TG and prevented TG-evoked co-immunoprecipitation between plasma membrane-located STIM1 and the Ca²+ permeable channel Orai1. These findings suggest that lipid raft domains are essential for the inactivation of SOCE by extracellular Ca²+ mediated by the interaction between plasma membrane-located STIM1 and Orai1.
Department of Physiology, Cell Physiology Research Group, University of Extremadura, Cáceres, Spain.
Natalia
N
Dionisio
Carmen
C
Galán
Isaac
I
Jardín
Ginés M
GM
Salido
Juan A
JA
Rosado
D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008345:Manganese / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D000071740:ORAI1 Protein; D000071737:Stromal Interaction Molecule 1; D019284:Thapsigargin / Q000494:pharmacology; D047392:beta-Cyclodextrins / Q000378:metabolism
D015220:Calcium Channels; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D008345:Manganese; D019284:Thapsigargin; D002118:Calcium