Phosphorylation of Histone H2B Serine 32 Is Linked to Cell Transformation

J Biol Chem. 2011 Jul 29;286(30):26628-37. doi: 10.1074/jbc.M110.215590. Epub 2011 Jun 6.

Abstract

Various types of post-translational modifications of the histone tails have been revealed, but a few modifications have been found within the histone core sequences. Histone core post-translational modifications have the potential to modulate nucleosome structure and DNA accessibility. Here, we studied the histone H2B core domain and found that phosphorylation of H2B serine 32 occurs in normal cycling and mitogen-stimulated cells. Notably, this phosphorylation is elevated in skin cancer cell lines and tissues compared with normal counterparts. The JB6 Cl41 mouse skin epidermal cell line is a well established model for tumor promoter-induced cell transformation and was used to study the function of H2B during EGF-induced carcinogenesis. Remarkably, cells overexpressing a nonphosphorylatable H2BS32A mutant exhibited suppressed growth and EGF-induced cell transformation, possibly because of decreased activation of activator protein-1, compared with control cells overexpressing wild type H2B. We identified ribosomal S6 kinase 2 (RSK2) as the kinase responsible for H2BS32 phosphorylation. Serum-starved JB6 cells contain very little endogenous H2BS32 phosphorylation, and EGF treatment induced this phosphorylation. The phosphorylation was attenuated in RSK2 knock-out MEFs and RSK2 knockdown JB6 cells. Taken together, our results demonstrate a novel role for H2B phosphorylation in cell transformation and show that H2BS32 phosphorylation is critical for controlling activator protein-1 activity, which is a major driver in cell transformation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Cell Transformation, Neoplastic / genetics
  • Cell Transformation, Neoplastic / metabolism*
  • Cell Transformation, Neoplastic / pathology
  • Epidermal Growth Factor / metabolism
  • Epidermis / metabolism*
  • Epidermis / pathology
  • HEK293 Cells
  • Histones / genetics
  • Histones / metabolism*
  • Humans
  • Mice
  • Mice, Knockout
  • Mutation, Missense
  • Phosphorylation / genetics
  • Ribosomal Protein S6 Kinases, 90-kDa / genetics
  • Ribosomal Protein S6 Kinases, 90-kDa / metabolism
  • Serine / genetics
  • Serine / metabolism*
  • Transcription Factor AP-1 / genetics
  • Transcription Factor AP-1 / metabolism

Substances

  • Histones
  • Transcription Factor AP-1
  • Serine
  • Epidermal Growth Factor
  • Ribosomal Protein S6 Kinases, 90-kDa
  • ribosomal protein S6 kinase, 90kDa, polypeptide 3