STIM1, Orai1 and hTRPC1 are important for thrombin- and ADP-induced aggregation in human platelets.
Ca(2+) entry, particularly store-operated Ca(2+) entry (SOCE), has been reported to be crucial for a variety of cellular functions. SOCE is a mechanism regulated by the Ca(2+) content of the stores, where the intraluminal Ca(2+) sensor STromal Interaction Molecule 1 (STIM1) has been reported to communicate the filling state of the intracellular Ca(2+) stores to the store-operated Ca(2+)-permeable channels in the plasma membrane, likely involving Orai1 and TRPC proteins, such as TRPC1. Here we have investigated the role of Orai1, STIM1 and TRPC1 in platelet aggregation, an event that occurs during the process of thrombosis and hemostasis. Electrotransjection of cells with anti-STIM1 (25-139) antibody, directed towards the Ca(2+)-binding motif, significantly reduced thrombin-induced aggregation and prevented ADP-evoked response. Extracellular application of the anti-STIM1 antibody, in order to block the function of plasma membrane-located STIM1, reduced thrombin- and ADP-stimulated platelet aggregation to a lesser extent. Introduction of an anti-Orai1 (288-301) antibody, which binds the STIM1-binding site located in the Orai1 C-terminus, or extracellular application of anti-hTRPC1 (557-571) antibody to impair hTRPC1 channel function, significantly reduced thrombin- and ADP-induced platelet aggregation. These findings suggest a role of STIM1, Orai1 and hTRPC1 in thrombin- and ADP-induced platelet aggregation probably through the regulation of Ca(2+) entry, which might become targets for the development of therapeutic strategies to treat platelet hyperactivity and thrombosis disorders.
Galán
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C
Department of Physiology, Cell Physiology Research Group, University of Extremadura, Cáceres 10071, Spain.
Zbidi
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H
Bartegi
A
A
Salido
G M
GM
Rosado
J A
JA
D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000818:Animals; D000906:Antibodies / Q000008:administration & dosage; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000494:pharmacology; D015220:Calcium Channels / Q000097:blood* / Q000276:immunology; D020013:Calcium Signaling; D006801:Humans; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000097:blood* / Q000276:immunology; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000097:blood* / Q000276:immunology; D000071740:ORAI1 Protein; D010974:Platelet Aggregation / Q000187:drug effects* / Q000502:physiology*; D000071737:Stromal Interaction Molecule 1; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors / Q000097:blood* / Q000276:immunology; D013917:Thrombin / Q000494:pharmacology*
D000906:Antibodies; D015220:Calcium Channels; 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; D000244:Adenosine Diphosphate; D013917:Thrombin; D002118:Calcium