Human vitamin D receptor phosphorylation by casein kinase II at Ser-208 potentiates transcriptional activation

Proc Natl Acad Sci U S A. 1996 Apr 16;93(8):3519-24. doi: 10.1073/pnas.93.8.3519.

Abstract

The potential functional significance of human 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] receptor (hVDR) phosphorylation at Ser-208 was evaluated by cotransfecting COS-7 kidney cells with hVDR constructs and the catalytic subunit of human casein kinase 11 (CK-11). Under these conditions, hVDR is intensely phosphorylated in a reaction that depends on both CK-II and the presence of Ser-208. The resulting hyperphosphorylated receptor is unaltered in its kinetics for binding the 1,25(OH)2D3 ligand, its partitioning into the nucleus, and its ability to associate with a vitamin D responsive element. Replacement of Ser-208 with glycine or alanine indicates that phosphorylation of hVDR at Ser-208 is not obligatory for 1,25(OH)2D3 action, but coexpression of wild-type hVDR and CK-11 elicits a dose-dependent enhancement of 1,25(OH)2D3-stimulated transcription of a vitamin D responsive element reporter construct. This enhancement by CK-II is abolished by mutating Ser-208 to glycine or alanine and does not occur with glucocorticoid receptor-mediated transcription. Therefore, phosphorylation of hVDR by CK-11 at Ser-208 specifically modulates its transcriptional capacity, suggesting that this covalent modification alters the conformation of VDR to potentiate its interaction with the machinery for DNA transcription.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Binding Sites / genetics
  • Casein Kinase II
  • Cell Line
  • DNA / metabolism
  • Humans
  • Kinetics
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Receptors, Calcitriol / chemistry
  • Receptors, Calcitriol / genetics
  • Receptors, Calcitriol / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Serine / chemistry
  • Subcellular Fractions / metabolism
  • Transcriptional Activation
  • Transfection

Substances

  • Receptors, Calcitriol
  • Recombinant Proteins
  • Serine
  • DNA
  • Casein Kinase II
  • Protein-Serine-Threonine Kinases