Drosophila CK2 phosphorylates Deadpan, a member of the HES family of basic-helix-loop-helix (bHLH) repressors

In Drosophila, protein kinase CK2 regulates a diverse array of developmental processes. One of these is cell-fate specification (neurogenesis) wherein CK2 regulates basic-helix-loop-helix (bHLH) repressors encoded by the Enhancer of Split Complex (E(spl)C). Specifically, CK2 phosphorylates and activ...

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Published in:Molecular and cellular biochemistry 2005-06, Vol.274 (1-2), p.133-139
Main Authors: Karandikar, Umesh C, Shaffer, Jonathan, Bishop, Clifton P, Bidwai, Ashok P
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Basic Helix-Loop-Helix Transcription Factors - chemistry
Casein Kinase II - chemistry
Catalytic Domain
Conserved Sequence
Drosophila
Drosophila Proteins - chemistry
Insects
Kinases
Molecular Sequence Data
Nuclear Proteins - chemistry
Phosphorylation
Recombinant Fusion Proteins - chemistry
Two-Hybrid System Techniques
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Summary:In Drosophila, protein kinase CK2 regulates a diverse array of developmental processes. One of these is cell-fate specification (neurogenesis) wherein CK2 regulates basic-helix-loop-helix (bHLH) repressors encoded by the Enhancer of Split Complex (E(spl)C). Specifically, CK2 phosphorylates and activates repressor functions of E(spl)M8 during eye development. In this study we describe the interaction of CK2 with an E(spl)-related bHLH repressor, Deadpan (Dpn). Unlike E(spl)-repressors which are expressed in cells destined for a non-neural cell fate, Dpn is expressed in the neuronal cells and is thought to control the activity of proneural genes. Dpn also regulates sex-determination by repressing sxl, the primary gene involved in sex differentiation. We demonstrate that Dpn is weakly phosphorylated by monomeric CK2alpha, whereas it is robustly phosphorylated by the embryo-holoenzyme, suggesting a positive role for CK2beta. The weak phosphorylation by CK2alpha is markedly stimulated by the activator polylysine to levels comparable to those with the holoenzyme. In addition, pull down assays indicate a direct interaction between Dpn and CK2. This is the first demonstration that Dpn is a partner and target of CK2, and raises the possibility that its repressor functions might also be regulated by phosphorylation.
ISSN:0300-8177
1573-4919
DOI:10.1007/s11010-005-2942-2