STIM1 regulates acidic Ca2+ store refilling by interaction with SERCA3 in human platelets.
Ca(2+) mobilization regulates a wide variety of cellular functions. Platelets possess agonist-releasable Ca(2+) stores in acidic organelles where sarcoendoplasmic reticulum Ca(2+)-ATPase-3 (SERCA) pump is involved in store refilling. Stromal interaction molecule 1 (STIM1), which has been presented as a central regulator of platelet function, is a Ca(2+) sensor of the intracellular Ca(2+) stores. Here we present that STIM1 is required for acidic store refilling. Electrotransjection of cells with anti-STIM1 (Y(231)-K(243)) antibody, directed towards a cytoplasmic sequence of STIM1, significantly reduced acidic store refilling, which was tested by remobilizing Ca(2+) from the acidic stores using 2,5-di-(t-butyl)-1,4-hydroquinone (TBHQ) after a brief refilling period that followed thrombin stimulation. Platelet treatment with thrombin or thapsigargin in combination with ionomycin, to induce extensive Ca(2+) store depletion, resulted in a transient increase in the interaction between STIM1 and SERCA3, reaching a maximum 30 s after stimulation. The coupling between STIM1 and SERCA3 was abolished by electrotransjection with anti-STIM1 antibody. The interaction between STIM1 and SERCA3 induced by thrombin or by treatment with thapsigargin plus ionomycin is reduced in platelets from type 2 diabetic patients, as well as Ca(2+) reuptake into the acidic Ca(2+) stores. These findings provide evidence for a role of STIM1 in acidic store refilling in platelets probably acting as a Ca(2+) sensor and regulating the activity of SERCA3. This action is impaired in platelets from type 2 diabetics, which might lead to the enhanced cytosolic Ca(2+) concentration observed and, therefore, in platelet hyperactivity.
López
Jose J
JJ
Department of Physiology, Cell Physiology Research Group, University of Extremadura, Caceres 10071, Spain.
Jardín
Isaac
I
Bobe
Regis
R
Pariente
Jose A
JA
Enouf
Jocelyne
J
Salido
Gines M
GM
Rosado
Juan A
JA
D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D016257:Fura-2 / Q000494:pharmacology; D005786:Gene Expression Regulation; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D000071737:Stromal Interaction Molecule 1; D013917:Thrombin / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
D002614:Chelating Agents; D006490:Hemostatics; D006873:Hydroquinones; D008565:Membrane Proteins; D009363:Neoplasm Proteins; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D014475:Uncoupling Agents; D012402:Rotenone; C018855:2-tert-butylhydroquinone; D013917:Thrombin; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506949:ATP2A3 protein, human; D000252:Calcium-Transporting ATPases; D002118:Calcium; D016257:Fura-2