Transcription-independent phosphorylation of the RNA polymerase II C-terminal domain (CTD) involves ERK kinases (MEK1/2).
The largest subunit of the mammalian RNA polymerase II possesses a C-terminal domain (CTD) consisting of 52 repeats of the consensus sequence, Tyr(1)-Ser(2)-Pro(3)-Thr(4)-Ser(5)-Pro(6)-Ser(7). Phosphorylation of the CTD is known to play a key role in gene expression. We now show that treatments such as osmotic and oxidative shocks or serum stimulation generate a new type of phosphorylated subunit, the IIm form. This IIm form might be generated in vivo by ERK-type MAP kinase phosphorylation as: (i) ERK1/2 are major CTD kinases found in cell extracts; (ii) the immunoreactivity of the IIm form against a panel of monoclonal antibodies indicates that the CTD is exclusively phosphorylated on Ser-5 in the repeats, like RNA polymerase II phosphorylated in vitro by an ERK1/2; and (iii) the IIm form does not appear when ERK activation is prevented by treating cells with low concentrations of highly specific inhibitors of MEK1/2. Since the IIm subunit is not affected by inhibition of transcription and is not bound to chromatin, it does not participate in transcription.
Bonnet
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F
Laboratoire de Régulation de l'Expression Génétique, CNRS UMR 8541, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris Cedex 05, France.
Vigneron
M
M
Bensaude
O
O
Dubois
M F
MF
D016475:3T3 Cells; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009997:Osmotic Pressure; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012319:RNA Polymerase II / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
D000911:Antibodies, Monoclonal; D004791:Enzyme Inhibitors; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D012319:RNA Polymerase II