title: Role of STIM1 in regulation of store-operated Ca2+ influx in pheochromocytoma cells.
abstract: Changes in the local environment such as pH (acidosis/alkalosis), temperature (hypothermia/hyperthermia), and agonist (glutamate) can adversely affect neuronal function, and are important factors in clinical situations such as anesthesia and intensive care. Regulation of intracellular Ca2+ ([Ca2+](i)) is key to neuronal function. Stromal interaction molecule (STIM1) has been recently recognized to trigger store-operated Ca2+ entry (SOCE), an important component of [Ca2+](i) regulation. Using differentiated, fura-2 loaded rat pheochromocytoma (PC12) cells transfected with small interference RNA for STIM1 (or vehicle), we examined the role of STIM1 in SOCE sensitivity to temperature, pH, and glutamate. SOCE was triggered following endoplasmic reticulum depletion. Cells were washed and exposed to altered pH (6.0-8.0), altered temperature (34-40 degrees C), or to glutamate. In non-transfected cells, SOCE was inhibited by acidosis or hypothermia, but increased with alkalosis and hyperthermia. Increasing glutamate concentrations progressively stimulated SOCE. STIM1 siRNA decreased SOCE at normal temperature and pH, and substantially decreased sensitivity to acidosis and hypothermia, eliminating the concentration-dependence to glutamate. Sensitivity of SOCE to these environmental parameters was less altered by decreased extracellular Ca2+ alone (with STIM1 intact). We conclude that STIM1 mediates exquisite susceptibility of SOCE to pH, temperature, and glutamate: factors that can adversely affect neuronal function under pathological conditions.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Thompson
authors.forename: Christina M
authors.initials: CM
authors.lastname: Pabelick
authors.forename: Y S
authors.initials: YS
authors.lastname: Prakash
mesh_terms: D000138:Acidosis / Q000378:metabolism; D000471:Alkalosis / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D045604:Extracellular Fluid / Q000378:metabolism; D005334:Fever / Q000378:metabolism; D016257:Fura-2; D018698:Glutamic Acid / Q000378:metabolism / Q000494:pharmacology; D006706:Homeostasis / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007035:Hypothermia / Q000378:metabolism; D007202:Indicators and Reagents; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D016716:PC12 Cells; D034741:RNA, Small Interfering; D051381:Rats; D000071737:Stromal Interaction Molecule 1; D013696:Temperature
chemical_list: D007202:Indicators and Reagents; D008562:Membrane Glycoproteins; D034741:RNA, Small Interfering; C518857:Stim1 protein, rat; D000071737:Stromal Interaction Molecule 1; D018698:Glutamic Acid; D002118:Calcium; D016257:Fura-2