A mitogen- and anisomycin-stimulated kinase phosphorylates HMG-14 in its basic amino-terminal domain in vivo and on isolated mononucleosomes

Michael J. Barratt, Catherine A. Hazzalin, Nikolai Zhelev, Louis C. Mahadevan

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

The rapid, transient induction of 80-100 immediate-early (IE) genes upon mitogenic stimulation occurs irrespective of protein synthesis and is mediated by modification of existing proteins. Two mechanisms, not mutually exclusive, involving modification either of sequence-specific transcription factors or of structural chromatin proteins primed by pre-association with responsive effectors are conceivable. Here, we show that upon IE gene induction, the non-histone high-mobility-group protein HMG-14, but not the related protein HMG-17, becomes serine phosphorylated in its basic, amino-terminal region close to where it binds nucleosomal DNA. Phosphorylation, normally transient, occurs independent of transcription and is quantitative and prolonged during superinduction. Brief micrococcal nuclease digestion substantially releases HMG-14 from nuclei in the mononucleosome-bound state. Finally, mononucleosomes prepared from mitogen-stimulated, but not control, cells contain a mitogen-activated kinase that phosphorylates HMG-14 in vitro on the same site(s) as in intact cells. The association of HMG-14 and its mitogen-activated kinase with nuclease-sensitive mononucleosomes has implications for models of mitogen-stimulated IE gene induction.

Original languageEnglish
Pages (from-to)4524-4535
Number of pages12
JournalEMBO Journal
Volume13
Issue number19
DOIs
Publication statusPublished - 1 Oct 1994

Keywords

  • Anisomycin
  • HMG-14 phosphorylation
  • IE gene induction
  • Mitogen
  • Nucleosomal HMG-14 kinase

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