title: Stimulation of the Ras-MAPK pathway leads to independent phosphorylation of histone H3 on serine 10 and 28.
abstract: The Ras-mitogen activated protein kinase (Ras-MAPK) pathway plays an integral role in the formation of human malignancies. Stimulation of this pathway results in phosphorylation of histone H3 at serines 10 and 28 and expression of immediate-early genes. Phosphorylated (serine 10) H3, which is also acetylated on lysine 14, is associated with immediate-early genes. In this report, we investigated the relationship between these two H3 phosphorylation events in parental and ras-transformed fibroblasts. Immunoblot analyses of two-dimensional gel patterns demonstrated that all three H3 variants were phosphorylated after stimulation of the Ras-MAPK pathway and during mitosis. Following stimulation of the Ras-MAPK pathway, H3 phosphorylated on serines 10 and 28 was excluded from regions of highly condensed chromatin and was present in increased levels in ras-transformed cells. Although H3 phosphorylated at serine 10 or 28 was dynamically acetylated, H3 phosphorylated at serine 28 had a higher steady state of acetylation than that of H3 phosphorylated at serine 10. When visualized with indirect immunofluorescence, most foci of phosphorylated serine 28 H3 did not co-localize with foci of H3 phosphorylated on serine 10 or phosphoacetylated on serine 10 and lysine 14, suggesting that these two phosphorylation events act separately to promote gene expression.
authors.affiliation: Manitoba Institute of Cell Biology, University of Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba, Canada R3E 0V9.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Dunn
authors.forename: James R
authors.initials: JR
authors.lastname: Davie
mesh_terms: D000818:Animals; D002471:Cell Transformation, Neoplastic; D005347:Fibroblasts; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation; D006657:Histones / Q000378:metabolism*; D015151:Immunoblotting; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000096:biosynthesis / Q000494:pharmacology*; D010766:Phosphorylation; D012694:Serine / Q000378:metabolism; D018631:ras Proteins / Q000096:biosynthesis / Q000494:pharmacology*
chemical_list: D006657:Histones; D012694:Serine; D020929:Mitogen-Activated Protein Kinase Kinases; D018631:ras Proteins