Diacylglycerols containing Omega 3 and Omega 6 fatty acids bind to RasGRP and modulate MAP kinase activation.
We elucidated the effects of different diacylglycerols (DAGs), i.e. 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG), 1-stearoyl-2-docosahexaenoyl-sn-glycerol (SDG), and 1-stearoyl-2-eicosapentaenoyl-sn-glycerol (SEG), on [3H]PDBu binding to RasGRP. The competition studies with these DAGs on [3H]PDBu binding to RasGRP revealed different Ki values for these DAG molecular species. Furthermore, we transfected human Jurkat T cells by a plasmid containing RasGRP and assessed the implication of endogenous DAGs on activation of MAP kinases ERK1/ERK2, induced by phorbol-12-myristate-13-acetate (PMA). In control cells, GF109203X, a protein kinase C inhibitor, inhibited ERK1/ERK2 activation. However, this agent curtailed but failed to completely diminish ERK1/ERK2 phosphorylation in RasGRP-overexpressing cells, though calphostin C, a DAG binding inhibitor, suppressed the phosphorylation of MAP kinases in these cells. In cells incubated with arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), PMA induced the production of endogenous DAGs containing these fatty acids, respectively: DAG-AA, DAG-DHA, and DAG-EPA. The inhibition of production of DAG-AA and DAG-DHA significantly inhibited MAP kinase activation in RasGRP overexpressing, but not in control, cells. Our study demonstrates that three DAG molecular species bind to RasGRP, but only DAG-AA and DAG-DHA participate in the modulation of RasGRP-mediated activation of MAP kinases in Jurkat T cells.
Unitè Propre de Recherche de l'Enseignement Supérieur Lipides, Université de Bourgogne, Faculté des Sciences, 6 Boulevard Gabriel, F-21000 Dijon, France.
Sihem
S
Madani
Aziz
A
Hichami
Mustapha
M
Cherkaoui-Malki
Naim A
NA
Khan
Mustapha
M
Charkaoui-Malki
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004075:Diglycerides / Q000737:chemistry*; D004281:Docosahexaenoic Acids / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015118:Eicosapentaenoic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D015525:Fatty Acids, Omega-3 / Q000378:metabolism*; D043371:Fatty Acids, Omega-6 / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D015151:Immunoblotting; D007211:Indoles / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D019169:Jurkat Cells; D007700:Kinetics; D020935:MAP Kinase Signaling System; D008301:Maleimides / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D004075:Diglycerides; D004791:Enzyme Inhibitors; D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D020662:Guanine Nucleotide Exchange Factors; D007211:Indoles; D008301:Maleimides; C491790:RASGRP1 protein, human; C491789:Rasgrp1 protein, rat; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate