title: Are Orai1 and Orai3 channels more important than calcium influx for cell proliferation?
abstract: Transformed and tumoral cells share the characteristic of being able to proliferate even when external calcium concentration is very low. We have investigated whether Human Embryonic Kidney 293 cells, human hepatoma cell Huh-7 and HeLa cells were able to proliferate when kept 72h in complete culture medium without external calcium. Our data showed that cell proliferation rate was similar over a range of external calcium concentration (2μM to 1.8mM). Incubation in the absence of external calcium for 72h had no significant effect on endoplasmic reticulum (ER) Ca(2+) contents but resulted in a significant decrease in cytosolic free calcium concentration in all 3 cell types. Cell proliferation rates were dependent on Orai1 and Orai3 expression levels in HEK293 and HeLa cells. Silencing Orai1 or Orai3 resulted in a 50% reduction in cell proliferation rate. Flow cytometry analysis showed that Orai3 induced a small but significant increase in cell number in G2/M phase. RO-3306, a cdk-1 inhibitor, induced a 90% arrest in G2/M reversible in less than 15min. Our data showed that progression through G2/M phase after release from RO-3306-induced cell cycle arrest was slower in both Orai1 and Orai3 knock-downs. Overexpressing Orai1, Orai3 and the dominant negative non-permeant mutants E106Q-Orai1 and E81Q-Orai3 induced a 50% increase in cell proliferation rate in HEK293 cells. Our data clearly demonstrated that Orai1 and Orai3 proteins are more important than calcium influx to control cell proliferation in some cell lines and that this process is probably independent of ICRAC and Iarc.
authors: INSERM, U1003, IFR147, Univ Lille 1, Villeneuve d'Ascq F-59655, France.
authors: Anne-Sophie
authors: AS
authors: Borowiec
authors: INSERM, U1003, IFR147, Univ Lille 1, Villeneuve d'Ascq F-59655, France.
authors: Gabriel
authors: G
authors: Bidaux
authors: INSERM U807, Hôpital Necker Enfants Malades, Université Paris 5, 156 rue de Vaugirard, Paris F-75730, France.
authors: Rachida
authors: R
authors: Tacine
authors: INSERM U613, Université Bretagne Occidentale, 46 rue Felix Le Dantec, Brest F-29218, France.
authors: Pauline
authors: P
authors: Dubar
authors: INSERM U845, Growth and Signalling Research Center, Université Paris 5, Bâtiment Leriche, 96 rue Didot, Paris F-75993, France.
authors: Natascha
authors: N
authors: Pigat
authors: INSERM, U1003, IFR147, Univ Lille 1, Villeneuve d'Ascq F-59655, France.
authors: Philippe
authors: P
authors: Delcourt
authors: INSERM U613, Université Bretagne Occidentale, 46 rue Felix Le Dantec, Brest F-29218, France.
authors: Olivier
authors: O
authors: Mignen
authors: INSERM, U1003, IFR147, Univ Lille 1, Villeneuve d'Ascq F-59655, France; INSERM U807, Hôpital Necker Enfants Malades, Université Paris 5, 156 rue de Vaugirard, Paris F-75730, France; INSERM U845, Growth and Signalling Research Center, Université Paris 5, Bâtiment Leriche, 96 rue Didot, Paris F-75993, France. Electronic address: thierry.capiod@inserm.fr.
authors: Thierry
authors: T
authors: Capiod
mesh_terms: D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002453:Cell Cycle; D049109:Cell Proliferation; D004247:DNA / Q000378:metabolism; D015536:Down-Regulation; D005434:Flow Cytometry; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D000071740:ORAI1 Protein
chemical_list: D015220:Calcium Channels; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; C522867:Orai3 protein, human; D004247:DNA; D002118:Calcium
keywords: Cell cycle; Mitosis; Store-independent calcium entry; Store-operated calcium entry