Inactivation of smad-transforming growth factor beta signaling by Ca(2+)-calmodulin-dependent protein kinase II

Mol Cell Biol. 2000 Nov;20(21):8103-11. doi: 10.1128/mcb.20.21.8103-8111.2000.

Abstract

Members of the transforming growth factor beta (TGF-beta) family transduce signals through Smad proteins. Smad signaling can be regulated by the Ras/Erk/mitogen-activated protein pathway in response to receptor tyrosine kinase activation and the gamma interferon pathway and also by the functional interaction of Smad2 with Ca(2+)-calmodulin. Here we report that Smad-TGF-beta-dependent transcriptional responses are prevented by expression of a constitutively activated Ca(2+)-calmodulin-dependent protein kinase II (Cam kinase II). Smad2 is a target substrate for Cam kinase II in vitro at serine-110, -240, and -260. Cam kinase II induces in vivo phosphorylation of Smad2 and Smad4 and, to a lesser extent, Smad3. A phosphopeptide antiserum raised against Smad2 phosphoserine-240 reacted with Smad2 in vivo when coexpressed with Cam kinase II and by activation of the platelet-derived growth factor receptor, the epidermal growth factor receptor, HER2 (c-erbB2), and the TGF-beta receptor. Furthermore, Cam kinase II blocked nuclear accumulation of a Smad2 and induced Smad2-Smad4 hetero-oligomerization independently of TGF-beta receptor activation, while preventing TGF-beta-dependent Smad2-Smad3 interactions. These findings provide a novel cross-talk mechanism by which Ca(2+)-dependent kinases activated downstream of multiple growth factor receptors antagonize cell responses to TGF-beta.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COS Cells
  • Calcium / metabolism
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Cell Line
  • Cell Nucleus / metabolism
  • Chromatography, Thin Layer
  • Cytoplasm / metabolism
  • DNA-Binding Proteins / metabolism
  • Glutathione Transferase / metabolism
  • Humans
  • Immunoblotting
  • Luciferases / metabolism
  • Microscopy, Fluorescence
  • Models, Genetic
  • Phosphorylation
  • Precipitin Tests
  • RNA / metabolism
  • Receptor, ErbB-2 / metabolism
  • Receptors, Transforming Growth Factor beta / metabolism
  • Recombinant Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Serine / metabolism
  • Signal Transduction
  • Smad2 Protein
  • Smad3 Protein
  • Smad4 Protein
  • Thapsigargin / pharmacology
  • Trans-Activators / metabolism
  • Transcription, Genetic
  • Transfection
  • Transforming Growth Factor beta / metabolism*

Substances

  • DNA-Binding Proteins
  • Receptors, Transforming Growth Factor beta
  • Recombinant Proteins
  • SMAD2 protein, human
  • SMAD3 protein, human
  • SMAD4 protein, human
  • Smad2 Protein
  • Smad3 Protein
  • Smad4 Protein
  • Trans-Activators
  • Transforming Growth Factor beta
  • Serine
  • RNA
  • Thapsigargin
  • Luciferases
  • Glutathione Transferase
  • Receptor, ErbB-2
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Calcium