Cyclin H binding to the RARalpha activation function (AF)-2 domain directs phosphorylation of the AF-1 domain by cyclin-dependent kinase 7.
The transcriptional activity of nuclear retinoic acid receptors (RARs), which act as RAR/retinoid X receptor (RXR) heterodimers, depends on two activation functions, AF-1 and AF-2, which are targets for phosphorylations and synergize for the activation of retinoic acid target genes. The N-terminal AF-1 domain of RARalpha is phosphorylated at S77 by the cyclin-dependent kinase (cdk)-activating kinase (CAK) subcomplex (cdk7/cyclin H/MAT1) of the general transcription factor TFIIH. Here, we show that phosphorylation of S77 governing the transcriptional activity of RARalpha depends on cyclin H binding at a RARalpha region that encompasses loop 8-9 and the N-terminal tip of helix 9 of the AF-2 domain. We propose a model in which the structural constraints of this region control the architecture of the RAR/RXR/TFIIH complex and therefore the efficiency of RARalpha phosphorylation by cdk7. To our knowledge, this study provides the first example of a cooperation between the AF-2 and AF-1 domains of RARs through a kinase complex.
Bour
Gaétan
G
Département de Biologie Cellulaire et de Transduction du Signal, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, UMR 7104, Illkirch, France.
Gaillard
Emilie
E
Bruck
Nathalie
N
Lalevée
Sébastien
S
Plassat
Jean-Luc
JL
Busso
Didier
D
Samama
Jean-Pierre
JP
Rochette-Egly
Cécile
C
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D056748:Cyclin H; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism*; D017931:DNA Primers; D008958:Models, Molecular; D010766:Phosphorylation; D011485:Protein Binding; D034741:RNA, Small Interfering; D018168:Receptors, Retinoic Acid / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D000072482:Retinoic Acid Receptor alpha; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018411:Spodoptera; D014158:Transcription, Genetic / Q000502:physiology; D000095043:Cyclin-Dependent Kinase-Activating Kinase
D056748:Cyclin H; D016213:Cyclins; D017931:DNA Primers; D034741:RNA, Small Interfering; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D018844:Cyclin-Dependent Kinases; D000095043:Cyclin-Dependent Kinase-Activating Kinase