Mirk protein kinase is activated by MKK3 and functions as a transcriptional activator of HNF1alpha

J Biol Chem. 2002 Jul 12;277(28):25040-6. doi: 10.1074/jbc.M203257200. Epub 2002 Apr 29.

Abstract

Mirk/Dyrk1B is an arginine-directed serine/threonine protein kinase that is expressed at low levels in most normal tissues but at elevated levels in many tumor cell lines and in normal skeletal muscle. Colon carcinoma cell lines stably overexpressing Mirk proliferated in serum-free medium, but the mechanism of Mirk action is unknown. DCoHm (dimerization cofactor of hepatocyte nuclear factor 1alpha ( HNF1alpha) from muscle), a novel gene of the DCoH family with 78% amino acid identity to DCoH, was identified as a Mirk-binding protein by yeast two-hybrid analysis and cloned. Mirk co-immunoprecipitated with DCoHm and bound to DCoHm in glutathione S-transferase pull-down assays. DCoH stabilizes HNF1alpha as a dimer and enhances its transcriptional activity on the beta-fibrinogen promoter reporter, and DCoHm had similar activity. Mirk enhanced HNF1alpha transcriptional activity in a dose-dependent manner, whereas two kinase-inactive Mirk mutants and a Mirk N-terminal deletion mutant did not. Mirk, DCoHm, and HNF1alpha formed a complex. Mirk bound to a specific region within the CREB-binding protein-binding region of HNF1alpha and phosphorylated HNF1alpha at a site adjacent to the Mirk-binding region. Conversely, the HNF1alpha binding domain was located within the first five conserved kinase subdomains of Mirk. Mirk co-immunoprecipitated with the MAPK kinase MKK3, an upstream activator of p38. MKK3 enhanced Mirk kinase activity and the transcriptional activation of HNF1alpha by Mirk, suggesting that Mirk, like p38, is activated by certain environmental stress agents. The Mirk-binding protein DCoH has been shown to be selectively expressed in colon carcinomas but not in normal tissue. Mirk may function as an HNF1alpha transcriptional activator in response to an MKK3-mediated stress signal, and the selective expression of DCoH could restrict the Mirk response to carcinoma cells.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Line
  • DNA-Binding Proteins*
  • Dimerization
  • Dyrk Kinases
  • Enzyme Activation
  • Hepatocyte Nuclear Factor 1
  • Hepatocyte Nuclear Factor 1-alpha
  • Hepatocyte Nuclear Factor 1-beta
  • Humans
  • Hydro-Lyases / chemistry
  • Hydro-Lyases / metabolism
  • MAP Kinase Kinase 3
  • Mice
  • Mitogen-Activated Protein Kinase Kinases / physiology*
  • Mitogen-Activated Protein Kinases / metabolism*
  • Molecular Sequence Data
  • Nuclear Proteins*
  • Protein Binding
  • Protein Serine-Threonine Kinases
  • Protein-Tyrosine Kinases / physiology*
  • Sequence Homology, Amino Acid
  • Trans-Activators / physiology*
  • Transcription Factors / genetics*

Substances

  • DNA-Binding Proteins
  • HNF1A protein, human
  • HNF1B protein, human
  • Hepatocyte Nuclear Factor 1-alpha
  • Hnf1a protein, mouse
  • Hnf1b protein, mouse
  • Nuclear Proteins
  • Trans-Activators
  • Transcription Factors
  • Hepatocyte Nuclear Factor 1
  • Hepatocyte Nuclear Factor 1-beta
  • Protein-Tyrosine Kinases
  • Protein Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 3
  • MAP2K3 protein, human
  • Map2k3 protein, mouse
  • Mitogen-Activated Protein Kinase Kinases
  • Hydro-Lyases
  • pterin-4a-carbinolamine dehydratase

Associated data

  • GENBANK/AF499009