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Characterization of MLKL-mediated Plasma Membrane Rupture in Necroptosis
08:55

Characterization of MLKL-mediated Plasma Membrane Rupture in Necroptosis

Published on: August 7, 2018

TNF-induced necroptosis in L929 cells is tightly regulated by multiple TNFR1 complex I and II members

N Vanlangenakker1, M J M Bertrand, P Bogaert

  • 1Department for Molecular Biomedical Research, VIB, Zwijnaarde-Ghent, Belgium.

Cell Death & Disease
|November 18, 2011
PubMed

Insights

Receptor-interacting protein 1 (RIP1) does not block TNF-induced necroptosis but suppresses apoptosis. RIP1-independent necroptosis is RIP3-mediated, revealing complex cell death regulation.

Area of Science:

  • Cell Biology
  • Immunology
  • Molecular Biology

Background:

  • Tumor necrosis factor (TNF) receptor 1 signaling triggers NF-κB activation and necroptosis.
  • Receptor-interacting protein 1 (RIP1) ubiquitination is cytoprotective, while cylindromatosis knockdown protects against TNF-induced necroptosis.
  • RIP1 mediates canonical NF-κB activation, prompting investigation into RIP1 ubiquitination versus NF-κB roles in cytoprotection.

Purpose of the Study:

  • To investigate the relative contributions of RIP1 ubiquitination and canonical NF-κB activation to cytoprotection against TNF-induced necroptosis.
  • To identify novel regulators of necroptosis and apoptosis.
  • To elucidate the role of RIP1 in TNF-induced cell death pathways.

Main Methods:

  • Utilized L929 cell lines with manipulated expression of key proteins (RIP1, RIP3, A20, cylindromatosis, caspase-8).
  • Assessed TNF-induced cell death, distinguishing between necroptosis and apoptosis.
  • Investigated NF-κB activation pathways in response to TNF signaling.

Main Results:

  • Attenuated NF-κB activation did not affect TNF-induced necroptosis.
  • A20 and linear ubiquitin chain assembly complex were identified as negative regulators of necroptosis.
  • RIP1 knockdown resulted in a switch from necroptosis to apoptosis, indicating RIP1 suppresses apoptosis.
  • Apoptosis-initiating factors (FADD, cFLIP, caspase-8) counteract necroptosis.
  • RIP1-independent, RIP3-mediated necroptosis was observed under specific TNF signaling conditions.

Conclusions:

  • RIP1's primary role in L929 cells is suppressing apoptosis, not mediating TNF-induced necroptosis.
  • RIP1-independent necroptosis pathways exist and are mediated by RIP3.
  • A20 and LUBAC are negative regulators of necroptosis.
  • Apoptosis regulators can inhibit necroptosis, highlighting intricate cell death crosstalk.

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