title: MAPKAP kinase 2 phosphorylates serum response factor in vitro and in vivo.
abstract: Several growth factor- and calcium-regulated kinases such as pp90(rsk) or CaM kinase IV can phosphorylate the transcription factor serum response factor (SRF) at serine 103 (Ser-103). However, it is unknown whether stress-regulated kinases can also phosphorylate SRF. We show that treatment of cells with anisomycin, arsenite, sodium fluoride, or tetrafluoroaluminate induces phosphorylation of SRF at Ser-103 in both HeLa and NIH3T3 cells. This phosphorylation is dependent on the kinase p38/SAPK2 and correlates with the activation of MAPKAP kinase 2 (MK2). MK2 phosphorylates SRF in vitro at Ser-103 with similar efficiency as the small heat shock protein Hsp25 and significantly better than CREB. Comparison of wild type murine fibroblasts with those derived from MK2-deficient mice (Mk(-/-)) reveals MK2 as the major SRF kinase induced by arsenite. These results demonstrate that SRF is targeted by several signal transduction pathways within cells and establishes SRF as a nuclear target for MAPKAP kinase 2.
mesh_terms: D016475:3T3 Cells; D000818:Animals; D018053:Arsenites / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D026362:Serum Response Factor; D015398:Signal Transduction / Q000187:drug effects; D013723:Teratogens / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2