title: Inactivation of smad-transforming growth factor beta signaling by Ca(2+)-calmodulin-dependent protein kinase II.
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.
authors.affiliation: Department of Cancer Medicine, Division of Medicine, Imperial College School of Medicine, Hammersmith Campus, London W12 ONN, United Kingdom.
authors.forename: S J
authors.initials: SJ
authors.lastname: Wicks
authors.forename: S
authors.initials: S
authors.lastname: Lui
authors.forename: N
authors.initials: N
authors.lastname: Abdel-Wahab
authors.forename: R M
authors.initials: RM
authors.lastname: Mason
authors.forename: A
authors.initials: A
authors.lastname: Chantry
mesh_terms: D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002855:Chromatography, Thin Layer; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008156:Luciferases / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D010766:Phosphorylation; D011233:Precipitin Tests; D012313:RNA / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D019284:Thapsigargin / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D002118:Calcium; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004268:DNA-Binding Proteins; D005982:Glutathione Transferase; D008156:Luciferases; D012313:RNA; D018719:Erb-b2 Receptor Tyrosine Kinases; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; D012694:Serine; D051899:Smad2 Protein; D051900:Smad3 Protein; D051901:Smad4 Protein; D019284:Thapsigargin; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; C497796:SMAD4 protein, human