Phosphorylation of activation functions AF-1 and AF-2 of RAR alpha and RAR gamma is indispensable for differentiation of F9 cells upon retinoic acid and cAMP treatment.
The role of RAR alpha 1 and RAR gamma 2 AF-1 and AF-2 activation functions and of their phosphorylation was investigated during RA-induced primitive and parietal differentiation of F9 cells. We found that: (i) primitive endodermal differentiation requires RAR gamma 2, whereas parietal endodermal differentiation requires both RAR gamma 2 and RAR alpha 1, and in all cases AF-1 and AF-2 must synergize; (ii) primitive endodermal differentiation requires the proline-directed kinase site of RAR gamma 2-AF-1, whereas parietal endodermal differentiation additionally requires that of RAR alpha 1-AF-1; (iii) the cAMP-induced parietal endodermal differentiation also requires the protein kinase A site of RAR alpha-AF-2, but not that of RAR gamma; and (iv) the AF-1-AF-2 synergism and AF-1 phosphorylation site requirements for RA-responsive gene induction are promoter context-dependent. Thus, AF-1 and AF-2 of distinct RARs exert specific cellular and molecular functions in a cell-autonomous system mimicking physiological situations, and their phosphorylation by kinases belonging to two main signalling pathways is required to enable RARs to transduce the RA signal during F9 cell differentiation.
Taneja
R
R
Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS-INSERM-ULP, Collège de France, Illkirch, France.
Rochette-Egly
C
C
Plassat
J L
JL
Penna
L
L
Gaub
M P
MP
Chambon
P
P
D000818:Animals; D001665:Binding Sites; D018236:Carcinoma, Embryonal / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004707:Endoderm / Q000166:cytology / Q000187:drug effects; D008024:Ligands; D051379:Mice; D010766:Phosphorylation; D018168:Receptors, Retinoic Acid / Q000819:agonists / Q000737:chemistry / Q000378:metabolism*; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D000097768:Retinoic Acid Receptor gamma
D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D008024:Ligands; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D014212:Tretinoin; D000097768:Retinoic Acid Receptor gamma; C000607072:Rara protein, mouse