Stimulation of the Ras-MAPK pathway leads to independent phosphorylation of histone H3 on serine 10 and 28.
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.
Dunn
Katherine L
KL
Manitoba Institute of Cell Biology, University of Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba, Canada R3E 0V9.
Davie
James R
JR
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*
D006657:Histones; D012694:Serine; D020929:Mitogen-Activated Protein Kinase Kinases; D018631:ras Proteins