Calcium-dependent regulation of phosphatidylserine synthesis in control and activated Jurkat T cells.
Activation of Jurkat T cells with phytohemagglutinin (PHA), CD3 or CD2 monoclonal antibodies (mAbs) results in a marked inhibition of phosphatidylserine (PS) synthesis. Activation of Jurkat T cells with PHA in a Ca(2+)-free medium resulted in an arrest of PS synthesis which was not reversed by the addition of Ca2+. The use of BAPTA to chelate Ca2+ ions released from intracellular stores prevented PHA-induced inhibition of PS synthesis. In addition, it was found that during activation, in the presence of BAPTA, a net Ca2+ influx paralleled an increase in PS synthesis, demonstrating that Ca2+ uptake caused an enhanced PS synthesis rather than an inhibition. The use of a CD2 mAb, D66, able to mobilize exclusively Ca2+ from intracellular stores, resulted in 51% inhibition of PS synthesis. N-Ethylmaleimide (NEM), which inhibits both the release of Ca2+ from internal stores and the influx of Ca2+, totally prevents the inhibition of PS synthesis induced by PHA, anti-CD3 or anti-CD2 mAbs. The presence, in the incubation medium, of either NDGA, TPCK or TPA, three drugs able to markedly inhibit Ca2+ influx without modifying the release of Ca2+ from internal stores, did not modify the inhibition of PS synthesis induced by PHA. Moreover all the drugs known to interact with calmodulin were also found to prevent the PHA-induced inhibition of this phospholipid. Taken together, these results show that the inhibition of PS synthesis induced by T cell activators is regulated by both calmodulin and Ca2+ ions recruited from intracellular compartments.
Unité de Recherches en Immunologie Cellulaire et Moléculaire, INSERM U210, Faculté de Médecine (Pasteur), Nice, France.
C
C
Aussel
C
C
Pelassy
D
D
Mary
J P
JP
Breittmayer
J L
JL
Cousin
B
B
Rossi
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D018801:CD2 Antigens; D017252:CD3 Complex; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002460:Cell Line; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D010718:Phosphatidylserines / Q000096:biosynthesis*; D010835:Phytohemagglutinins / Q000494:pharmacology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D011971:Receptors, Immunologic / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D018801:CD2 Antigens; D017252:CD3 Complex; D002147:Calmodulin; D010718:Phosphatidylserines; D010835:Phytohemagglutinins; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D005033:Ethylmaleimide; D002118:Calcium