Keywords :
Amino Acid Sequence; CCAAT-Enhancer-Binding Protein-delta/genetics/metabolism; Casein Kinase II/antagonists & inhibitors/genetics/metabolism; Catalytic Domain; Conserved Sequence; HCT116 Cells; Humans; Molecular Sequence Data; Phosphorylation; Protein Interaction Domains and Motifs; Protein Kinase Inhibitors/pharmacology; Transcriptome; Protein kinase CK2; Protein-protein interaction; Transcription; Transcription factor
Abstract :
[en] Protein kinase CK2 plays an essential role in cell viability in lower and higher eukaryotes. As a global regulator it phosphorylates and thereby regulates a broad array of cellular targets including a large number of transcription factors. Here, we have identified the CCAAT/enhancer binding protein delta (C/EBPdelta) as a new substrate for CK2. Using point mutants of C/EBPdelta the major phosphorylation site for CK2 was mapped to serine 57, which is located within the transactivation domain of C/EBPdelta. For proper functioning as a transcription factor C/EBPdelta has to be translocated into the nucleus where it forms heterodimers with other members of the C/EBP family of proteins and ATF4. Here, we found that CK2 phosphorylation does neither influence the subcellular localization of C/EBPdelta nor its interaction with C/EBPbeta, but rather does CK2 phosphorylation modulate the transcriptional activity of C/EBPdelta. Moreover, we found that CK2 bound to C/EBPdelta, which might help to target CK2 to the transcriptional machinery where it can phosphorylate other transcription factors or co-activators.
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