Regulation of Raf-1 kinase by TNF via its second messenger ceramide and cross-talk with mitogenic signalling

Gertraud Müller, Peter Storz, Soizic Bourteele, Heike Döppler, Klaus Pfizenmaier, Harald Mischak, Alex Philipp, Christian Kaiser, Walter Kolch

Research output: Contribution to journalArticlepeer-review

99 Scopus citations

Abstract

Raf-1 kinase is a central regulator of mitogenic signal pathways, whereas its general role in signal transduction of tumour necrosis factor (TNF) is less well defined. We have investigated mechanisms of Raf-1 regulation by TNF and its messenger ceramide in cell-free assays, insect and mammalian cell lines. In vitro, ceramide specifically bound to the purified catalytic domain and enhanced association with activated Ras proteins, but did not affect the kinase activity of Raf-1. Cell-permeable ceramides induced a marked increase of Ras-Raf-1 complexes in cells co-expressing Raf-1 and activated Ras. Likewise, a fast elevation of the endogeneous ceramide level, induced by TNF treatment of human Kym-1 rhabdomyosarcoma cells, was followed by stimulation of Ras-Raf-1 association without significant Raf-1 kinase activation. Failure of TNF or ceramide to induce Raf-1 kinase was observed in several TNF-responsive cell lines. Both TNF and exogeneous C6-ceramide interfered with the mitogenic activation of Raf-1 and ERK by epidermal growth factor and down-regulated v-Src-induced Raf-1 kinase activity. TNF also induced the translocation of Raf-1 from the cytosolic to the particulate fraction, indicating that this negative regulatory cross-talk occurs at the cell membrane. Interference with mitogenic signals at the level of Raf-1 could be an important initial step in TNF's cytostatic action.

Original languageEnglish (US)
Pages (from-to)732-742
Number of pages11
JournalEMBO Journal
Volume17
Issue number3
DOIs
StatePublished - Feb 2 1998

Keywords

  • Ceramide
  • Epidermal growth factor
  • Raf-1 kinase
  • Ras
  • Tumour necrosis factor

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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