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Analysis of the c-KIT Ligand Promoter Using Chromatin Immunoprecipitation
Published on: June 27, 2017
CK2 phosphorylation of C/EBPδ regulates its transcription factor activity
Lisa Schwind1, Andreas D Zimmer1, Claudia Götz1
1Medical Biochemistry and Molecular Biology, Saarland University, Building 44, D-66424 Homburg, Germany.
Abstract:
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 δ (C/EBPδ) as a new substrate for CK2. Using point mutants of C/EBPδ the major phosphorylation site for CK2 was mapped to serine 57, which is located within the transactivation domain of C/EBPδ. For proper functioning as a transcription factor C/EBPδ 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/EBPδ nor its interaction with C/EBPβ, but rather does CK2 phosphorylation modulate the transcriptional activity of C/EBPδ. Moreover, we found that CK2 bound to C/EBPδ, which might help to target CK2 to the transcriptional machinery where it can phosphorylate other transcription factors or co-activators.
Insights
Protein kinase CK2 phosphorylates CCAAT/enhancer binding protein δ (C/EBPδ), a key transcription factor. This phosphorylation modulates C/EBPδ
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Protein kinase CK2 is a crucial regulator of cell viability.
- CK2 phosphorylates numerous cellular targets, including transcription factors.
- CCAAT/enhancer binding protein δ (C/EBPδ) is involved in cellular processes.
Purpose of the Study:
- To identify new substrates for protein kinase CK2.
- To investigate the role of CK2 in regulating C/EBPδ function.
Main Methods:
- Site-directed mutagenesis to identify phosphorylation sites.
- Western blotting and co-immunoprecipitation to assess protein interactions and localization.
- Reporter assays to measure transcriptional activity.
Main Results:
- C/EBPδ was identified as a novel substrate for CK2.
- Serine 57 in the transactivation domain was mapped as the major CK2 phosphorylation site.
- CK2 phosphorylation of C/EBPδ modulates its transcriptional activity without affecting localization or C/EBPβ interaction.
Conclusions:
- CK2 phosphorylation regulates the transcriptional activity of C/EBPδ.
- CK2 may target the transcriptional machinery through its interaction with C/EBPδ.
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