The phosphorylation site located in the A region of retinoic X receptor alpha is required for the antiproliferative effect of retinoic acid (RA) and the activation of RA target genes in F9 cells.
Mouse F9 embryocarcinoma cells constitute a well established cell autonomous model system for investigating retinoic acid (RA) signaling in vitro. RA induces the differentiation of F9 cells grown as monolayers into endodermal-like cells and decreases their rate of proliferation. Knock-out of the retinoic X receptor alpha (RXRalpha) gene abolishes endodermal differentiation and the induction of several endogenous RA-responsive genes. RXRalpha null cells are also drastically impaired in their antiproliferative response to RA. The role of the RXRalpha phosphorylation site located in the N-terminal A region (Ser(22)) has been investigated here by establishing cell lines re-expressing RXRalpha either wild type or mutated at the phosphorylation site (RXRalphaS22A) in a RXRalpha-null background. We show that Ser(22) is dispensable for RA-induced endodermal differentiation but is crucial for the expression of several RA-responsive genes. Ser(22) is also indispensable for the antiproliferative effect of RA and necessary for the RA-induced down-regulation of p21(CIP) and p27(KIP) CKIs proteins that are known to be involved in the control of cell cycle progression.
Bastien
Julie
J
Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP 163, 67404 Illkirch Cedex, France.
Adam-Stitah
Sylvie
S
Plassat
Jean-Luc
JL
Chambon
Pierre
P
Rochette-Egly
Cecile
C
D000818:Animals; D001665:Binding Sites; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002455:Cell Division; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000378:metabolism; D015536:Down-Regulation; D004707:Endoderm / Q000166:cytology; D015151:Immunoblotting; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D011485:Protein Binding; D018168:Receptors, Retinoic Acid / Q000737:chemistry* / Q000378:metabolism; D047488:Retinoid X Receptors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014212:Tretinoin / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000378:metabolism
C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D012694:Serine; D014212:Tretinoin