Interaction of STIM1 with endogenously expressed human canonical TRP1 upon depletion of intracellular Ca2+ stores.
STIM1 (stromal interaction molecule 1) has recently been proposed to communicate the intracellular Ca(2+) stores with the plasma membrane to mediate store-operated Ca(2+) entry. Here we describe for the first time that Ca(2+) store depletion stimulates rapid STIM1 surface expression and association with endogenously expressed human canonical TRP1 (hTRPC1) independently of rises in cytosolic free Ca(2+) concentration. These events require the support of the actin cytoskeleton in human platelets, as reported for the coupling between type II inositol 1,4,5-trisphosphate receptor in the Ca(2+) stores and hTRPC1 in the plasma membrane, which has been suggested to underlie the activation of store-operated Ca(2+) entry in these cells. Electrotransjection of cells with anti-STIM1 antibody, directed toward the N-terminal sequence that includes the Ca(2+)-binding region, prevented the migration of STIM1 toward the plasma membrane, the interaction between STIM1 and hTRPC1, the coupling between hTRPC1 and type II inositol 1,4,5-trisphosphate receptor, and reduced store-operated Ca(2+) entry. These findings provide evidence for a role of STIM1 in the activation of store-operated Ca(2+) entry probably acting as a Ca(2+) sensor.
López
José J
JJ
Department of Physiology, Cellular Physiology Research Group, University of Extremadura, 10071 Cáceres, Spain.
Salido
Ginés M
GM
Pariente
José A
JA
Rosado
Juan A
JA
D000199:Actins / Q000502:physiology; D001792:Blood Platelets / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008565:Membrane Proteins / Q000032:analysis / Q000502:physiology*; D009363:Neoplasm Proteins / Q000032:analysis / Q000502:physiology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels / Q000502:physiology*
D000199:Actins; D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D018160:Receptors, Cytoplasmic and Nuclear; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels; C096351:transient receptor potential cation channel, subfamily C, member 1; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium