LC3/GABARAPs drive ubiquitin-independent recruitment of Optineurin and NDP52 to amplify mitophagy

Nat Commun. 2019 Jan 24;10(1):408. doi: 10.1038/s41467-019-08335-6.

Abstract

Current models of selective autophagy dictate that autophagy receptors, including Optineurin and NDP52, link cargo to autophagosomal membranes. This is thought to occur via autophagy receptor binding to Atg8 homologs (LC3/GABARAPs) through an LC3 interacting region (LIR). The LIR motif within autophagy receptors is therefore widely recognised as being essential for selective sequestration of cargo. Here we show that the LIR motif within OPTN and NDP52 is dispensable for Atg8 recruitment and selectivity during PINK1/Parkin mitophagy. Instead, Atg8s play a critical role in mediating ubiquitin-independent recruitment of OPTN and NDP52 to growing phagophore membranes via the LIR motif. The additional recruitment of OPTN and NDP52 amplifies mitophagy through an Atg8-dependent positive feedback loop. Rather than functioning in selectivity, our discovery of a role for the LIR motif in mitophagy amplification points toward a general mechanism by which Atg8s can recruit autophagy factors to drive autophagosome growth and amplify selective autophagy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Amino Acid Motifs
  • Apoptosis Regulatory Proteins
  • Autophagosomes / metabolism
  • Autophagy / physiology
  • Autophagy-Related Protein 8 Family / metabolism
  • Carrier Proteins / metabolism
  • Cell Cycle Proteins
  • HeLa Cells
  • Humans
  • Membrane Transport Proteins
  • Microtubule-Associated Proteins / metabolism*
  • Mitochondria / genetics
  • Mitochondria / metabolism
  • Mitophagy / physiology*
  • Nuclear Proteins / metabolism*
  • Protein Binding
  • Protein Kinases / metabolism
  • Transcription Factor TFIIIA / metabolism*
  • Ubiquitin / metabolism*
  • Ubiquitin-Protein Ligases / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Apoptosis Regulatory Proteins
  • Autophagy-Related Protein 8 Family
  • CALCOCO2 protein, human
  • Carrier Proteins
  • Cell Cycle Proteins
  • GABARAP protein, human
  • GABARAPL2 protein, human
  • MAP1LC3A protein, human
  • Membrane Transport Proteins
  • Microtubule-Associated Proteins
  • Nuclear Proteins
  • OPTN protein, human
  • Transcription Factor TFIIIA
  • Ubiquitin
  • Ubiquitin-Protein Ligases
  • parkin protein
  • Protein Kinases
  • PTEN-induced putative kinase