Akt Regulates TNFα synthesis downstream of RIP1 kinase activation during necroptosis

PLoS One. 2013;8(3):e56576. doi: 10.1371/journal.pone.0056576. Epub 2013 Mar 1.

Abstract

Necroptosis is a regulated form of necrotic cell death that has been implicated in the pathogenesis of various diseases including intestinal inflammation and systemic inflammatory response syndrome (SIRS). In this work, we investigated the signaling mechanisms controlled by the necroptosis mediator receptor interacting protein-1 (RIP1) kinase. We show that Akt kinase activity is critical for necroptosis in L929 cells and plays a key role in TNFα production. During necroptosis, Akt is activated in a RIP1 dependent fashion through its phosphorylation on Thr308. In L929 cells, this activation requires independent signaling inputs from both growth factors and RIP1. Akt controls necroptosis through downstream targeting of mammalian Target of Rapamycin complex 1 (mTORC1). Akt activity, mediated in part through mTORC1, links RIP1 to JNK activation and autocrine production of TNFα. In other cell types, such as mouse lung fibroblasts and macrophages, Akt exhibited control over necroptosis-associated TNFα production without contributing to cell death. Overall, our results provide new insights into the mechanism of necroptosis and the role of Akt kinase in both cell death and inflammatory regulation.

Publication types

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

MeSH terms

  • Animals
  • Apoptosis / genetics
  • Cell Line
  • Enzyme Activation
  • Fibroblasts / metabolism*
  • Fibroblasts / pathology
  • Gene Expression Regulation
  • Humans
  • Macrophages / metabolism*
  • Macrophages / pathology
  • Mechanistic Target of Rapamycin Complex 1
  • Mice
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism
  • Multiprotein Complexes
  • Necrosis / genetics
  • Necrosis / metabolism*
  • Necrosis / pathology
  • Phosphorylation
  • Proteins / genetics
  • Proteins / metabolism
  • Proto-Oncogene Proteins c-akt / genetics*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptor-Interacting Protein Serine-Threonine Kinases / genetics*
  • Receptor-Interacting Protein Serine-Threonine Kinases / metabolism
  • Signal Transduction
  • TOR Serine-Threonine Kinases
  • Threonine / metabolism
  • Tumor Necrosis Factor-alpha / biosynthesis*
  • Tumor Necrosis Factor-alpha / genetics

Substances

  • Multiprotein Complexes
  • Proteins
  • Tumor Necrosis Factor-alpha
  • Threonine
  • TOR Serine-Threonine Kinases
  • Mechanistic Target of Rapamycin Complex 1
  • Proto-Oncogene Proteins c-akt
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • Ripk1 protein, mouse
  • Mitogen-Activated Protein Kinases