Activated MLKL attenuates autophagy following its translocation to intracellular membranes

J Cell Sci. 2019 Feb 28;132(5):jcs220996. doi: 10.1242/jcs.220996.

Abstract

Necroptosis is an inflammatory form of programmed cell death mediated by the pseudokinase mixed-lineage kinase domain-like protein (MLKL). Upon phosphorylation by receptor-interacting protein kinase-3 (RIPK3), MLKL oligomerizes, and translocates to and disrupts the plasma membrane, thereby causing necroptotic cell lysis. Herein, we show that activation of necroptosis in mouse dermal fibroblasts (MDFs) and HT-29 human colorectal cancer cells results in accumulation of the autophagic marker, lipidated LC3B (also known as MAP1LC3B), in an MLKL-dependent manner. Unexpectedly, the necroptosis-induced increase in lipidated LC3B was due to inhibition of autophagic flux, not the activation of autophagy. Inhibition of autophagy by MLKL correlated with a decrease in autophagosome and/or autolysosome function, and required the association of activated MLKL with intracellular membranes. Collectively, our findings uncover an additional role for the MLKL pseudokinase, namely to inhibit autophagy during necroptosis.

Keywords: Autophagy; LC3; MLKL; Necroptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagosomes / metabolism*
  • Autophagy
  • Clustered Regularly Interspaced Short Palindromic Repeats
  • Colorectal Neoplasms / metabolism*
  • Colorectal Neoplasms / pathology
  • Dermis / pathology*
  • Fibroblasts / metabolism*
  • Fibroblasts / pathology
  • Gene Knockout Techniques
  • HT29 Cells
  • Humans
  • Intracellular Membranes / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Necroptosis
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Protein Transport

Substances

  • MLKL protein, human
  • MLKL protein, mouse
  • Protein Kinases