Abstract
Activated by the RAS-MAPK signaling pathway, MSK1 is recruited to immediate-early gene (IEG) regulatory regions, where it phosphorylates histone H3 at Ser-10 or Ser-28. Chromatin remodelers and modifiers are then recruited by 14-3-3 proteins, readers of phosphoserine marks, leading to the occupancy of IEG promoters by the initiation-engaged form of RNA polymerase II and the onset of transcription. In this study, we show that this mechanism of IEG induction, initially elucidated in parental 10T1/2 murine fibroblast cells, applies to metastatic Hras1-transformed Ciras-3 cells. As the RAS-MAPK pathway is constitutively activated in Ciras-3 cells, MSK1 activity and phosphorylated H3 steady-state levels are elevated. We found that steady-state levels of the IEG products AP-1 and COX-2 were also elevated in Ciras-3 cells. When MSK1 activity was inhibited or MSK1 expression was knocked down in Ciras-3 cells, the induction of IEG expression and the steady-state levels of COX-2, FRA-1, and JUN were greatly reduced. Furthermore, MSK1 knockdown Ciras-3 cells lost their malignant phenotype, as reflected by the absence of anchorage-independent growth.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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14-3-3 Proteins / metabolism
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Animals
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Cell Line
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Cell Transformation, Neoplastic*
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Chromatin Assembly and Disassembly / drug effects
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Cyclooxygenase 2 / metabolism
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Fibroblasts / cytology
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Fibroblasts / metabolism*
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Fibroblasts / pathology*
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Genes, Immediate-Early / genetics
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Histones / metabolism
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Isoquinolines / pharmacology
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Mice
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Oncogene Protein p21(ras) / genetics*
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Phenotype
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Phorbol Esters / pharmacology
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Phosphorylation / drug effects
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Proto-Oncogene Proteins c-fos / metabolism
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Proto-Oncogene Proteins c-jun / metabolism
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Regulatory Sequences, Nucleic Acid / genetics
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Ribosomal Protein S6 Kinases, 90-kDa / antagonists & inhibitors
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Ribosomal Protein S6 Kinases, 90-kDa / metabolism*
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Sulfonamides / pharmacology
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Transcriptional Activation / drug effects
Substances
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14-3-3 Proteins
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Histones
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Isoquinolines
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Phorbol Esters
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Proto-Oncogene Proteins c-fos
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Proto-Oncogene Proteins c-jun
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Sulfonamides
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fos-related antigen 1
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Cyclooxygenase 2
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Ribosomal Protein S6 Kinases, 90-kDa
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mitogen and stress-activated protein kinase 1
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Oncogene Protein p21(ras)
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N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide