title: The role of plasma membrane STIM1 and Ca(2+)entry in platelet aggregation. STIM1 binds to novel proteins in human platelets.
abstract: Ca(2+) elevation is essential to platelet activation. STIM1 senses Ca(2+) in the endoplasmic reticulum and activates Orai channels allowing store-operated Ca(2+) entry (SOCE). STIM1 has also been reported to be present in the plasma membrane (PM) with its N-terminal region exposed to the outside medium but its role is not fully understood. We have examined the effects of the antibody GOK/STIM1, which recognises the N-terminal region of STIM1, on SOCE, agonist-stimulated Ca(2+) entry, surface exposure, in vitro thrombus formation and aggregation in human platelets. We also determined novel binding partners of STIM1 using proteomics. The dialysed GOK/STIM1 antibody failed to reduced thapsigargin- and agonist-mediated Ca(2+) entry in Fura2-labelled cells. Using flow cytometry we detect a portion of STIM1 to be surface-exposed. The dialysed GOK/STIM1 antibody reduced thrombus formation by whole blood on collagen-coated capillaries under flow and platelet aggregation induced by collagen. In immunoprecipitation experiments followed by proteomic analysis, STIM1 was found to extract a number of proteins including myosin, DOCK10, thrombospondin-1 and actin. These studies suggest that PM STIM1 may facilitate platelet activation by collagen through novel interactions at the plasma membrane while the essential Ca(2+)-sensing role of STIM1 is served by the protein in the ER.
authors.affiliation: Cardiovascular Division, BHF Centre for Research Excellence, King's College London, Franklin Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Ambily
authors.affiliation: Institute of Cardiovascular and Metabolic Research and School of Biological Sciences, University of Reading, Reading, United Kingdom.
authors.forename: W J
authors.initials: WJ
authors.lastname: Kaiser
authors.affiliation: Cardiovascular Division, BHF Centre for Research Excellence, King's College London, Franklin Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Pierro
authors.affiliation: Cardiovascular Division, BHF Centre for Research Excellence, King's College London, Franklin Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: E V
authors.initials: EV
authors.lastname: Chamberlain
authors.affiliation: Cardiovascular Division, BHF Centre for Research Excellence, King's College London, Franklin Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.affiliation: Institute of Cardiovascular and Metabolic Research and School of Biological Sciences, University of Reading, Reading, United Kingdom.
authors.forename: C I
authors.initials: CI
authors.lastname: Jones
authors.affiliation: Cardiovascular Division, BHF Centre for Research Excellence, King's College London, Franklin Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom.
authors.forename: N
authors.initials: N
authors.lastname: Kassouf
authors.affiliation: Institute of Cardiovascular and Metabolic Research and School of Biological Sciences, University of Reading, Reading, United Kingdom.
authors.forename: J M
authors.initials: JM
authors.lastname: Gibbins
authors.affiliation: Cardiovascular Division, BHF Centre for Research Excellence, King's College London, Franklin Wilkins Building, Stamford Street, London SE1 9NH, United Kingdom. Electronic address: kalwant.authi@kcl.ac.uk.
authors.forename: K S
authors.initials: KS
authors.lastname: Authi
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000813:Anilides / Q000494:pharmacology; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D001792:Blood Platelets; D002118:Calcium; D020013:Calcium Signaling / Q000187:drug effects / Q000276:immunology; D003094:Collagen / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D007473:Ion Channels / Q000187:drug effects; D007546:Isoquinolines / Q000494:pharmacology; D008565:Membrane Proteins / Q000276:immunology*; D009218:Myosins / Q000378:metabolism; D009363:Neoplasm Proteins / Q000276:immunology*; D015539:Platelet Activation / Q000187:drug effects / Q000276:immunology*; D010974:Platelet Aggregation / Q000276:immunology*; D011485:Protein Binding / Q000276:immunology; D000071737:Stromal Interaction Molecule 1; D019284:Thapsigargin / Q000494:pharmacology; D013830:Thiadiazoles / Q000494:pharmacology; D013927:Thrombosis / Q000276:immunology; D019700:Thrombospondin 1 / Q000378:metabolism
chemical_list: D000081:Acetamides; D000199:Actins; D000813:Anilides; D000906:Antibodies; D002118:Calcium; D003094:Collagen; D004791:Enzyme Inhibitors; D020662:Guanine Nucleotide Exchange Factors; D007473:Ion Channels; D007546:Isoquinolines; D008565:Membrane Proteins; D009218:Myosins; D009363:Neoplasm Proteins; D000071737:Stromal Interaction Molecule 1; D019284:Thapsigargin; D013830:Thiadiazoles; D019700:Thrombospondin 1; C476308:4-methyl-4'-(3,5-bis(trifluoromethyl)-1H-pyrazol-1-yl)-1,2,3-thiadiazole-5-carboxanilide; C530992:DOCK10 protein, human; C103530:STIM1 protein, human; C081356:LOE 908
keywords: 1,2-diacyl-sn-glycerol; 1-Oleoyl-2-acetyl-sn-glycerol; Aggregation; Ca(2+) entry; Collagen; DAG; OAG; PM; SOCE; STIM1; TG; TRPC; Thrombospondin-1; plasma membrane; store operated Ca(2+) entry; stromal interaction molecule 1; thapsigargin; transient receptor potential canonical