G9a-mediated lysine methylation alters the function of CCAAT/enhancer-binding protein-beta.
The functional capacity of the transcriptional regulatory CCAAT/enhancer-binding protein-beta (C/EBPbeta) is governed by protein interactions and post-translational protein modifications. In a proteome-wide interaction screen, the histone-lysine N-methyltransferase, H3 lysine 9-specific 3 (G9a), was found to directly interact with the C/EBPbeta transactivation domain (TAD). Binding between G9a and C/EBPbeta was confirmed by glutathione S-transferase pulldown and co-immunoprecipitation. Metabolic labeling showed that C/EBPbeta is post-translationally modified by methylation in vivo. A conserved lysine residue in the C/EBPbeta TAD served as a substrate for G9a-mediated methylation. G9a, but not a methyltransferase-defective G9a mutant, abrogated the transactivation potential of wild type C/EBPbeta. A C/EBPbeta TAD mutant that contained a lysine-to-alanine exchange was resistant to G9a-mediated inhibition. Moreover, the same mutation conferred super-activation of a chromatin-embedded, endogenous C/EBPbeta target gene. Our data identify C/EBPbeta as a direct substrate of G9a-mediated post-translational modification that alters the functional properties of C/EBPbeta during gene regulation.
Pless
Ole
O
Max Delbrück Center for Molecular Medicine, Humboldt University of Berlin, Berlin, Germany.
Kowenz-Leutz
Elisabeth
E
Knoblich
Maria
M
Lausen
Jörn
J
Beyermann
Michael
M
Walsh
Martin J
MJ
Leutz
Achim
A
D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006649:Histocompatibility Antigens / Q000235:genetics / Q000378:metabolism*; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000502:physiology; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology*
D022782:CCAAT-Enhancer-Binding Protein-beta; D006649:Histocompatibility Antigens; D020543:Proteome; C445405:EHMT2 protein, human; D011495:Histone-Lysine N-Methyltransferase