Involvement of lysosomal integral membrane protein-2 in the activation of autophagy

Biochem Biophys Res Commun. 2020 Dec 17;533(4):976-982. doi: 10.1016/j.bbrc.2020.09.114. Epub 2020 Sep 30.

Abstract

Lysosomal integral membrane protein-2 (LIMP-2) is a type III transmembrane protein that is highly glycosylated and mainly localized to the lysosomal membrane. The diverse functions of LIMP-2 are currently being uncovered; however, its participation in macroautophagy, usually described as autophagy, has not yet been well-investigated. To determine the possible involvement of LIMP-2 in autophagic activity, we examined the intracellular amount of microtubule-associated protein 1 light chain 3 (LC3)-II, which is well-correlated with autophagosome levels, in exogenous rat LIMP-2-expressing COS7 and HEK293 cells. Transient or stable expression of LIMP-2-myc significantly increased the levels of LC3-II. Conversely, knockdown of LIMP-2 decreased the LC3-II levels in NIH3T3 cells. Furthermore, approaches using lysosomal protease inhibitors and mCherry-GFP-LC3 fluorescence suggested that exogenous expression of LIMP-2 increased the biogenesis of autophagosomes rather than decreased the lysosomal turnover of LC3-II. Considering the results of the biochemical assay and the quantitative fluorescence assay together, it is suggested that LIMP-2 has a possible involvement in autophagic activity, especially autophagosome biogenesis.

Keywords: LC3-II; LIMP-2; Lysosomes; Macroautophagy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagosomes / metabolism
  • Autophagy / physiology*
  • CD36 Antigens / antagonists & inhibitors
  • CD36 Antigens / genetics
  • CD36 Antigens / metabolism*
  • COS Cells
  • Chlorocebus aethiops
  • Gene Knockdown Techniques
  • HEK293 Cells
  • Humans
  • Lysosomal Membrane Proteins / antagonists & inhibitors
  • Lysosomal Membrane Proteins / genetics
  • Lysosomal Membrane Proteins / metabolism*
  • Lysosomes / metabolism
  • Mice
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • NIH 3T3 Cells
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism

Substances

  • CD36 Antigens
  • Lamp1 protein, mouse
  • Lysosomal Membrane Proteins
  • MAP1LC3B protein, human
  • Map1lc3b protein, mouse
  • Microtubule-Associated Proteins
  • RNA, Messenger
  • Recombinant Proteins
  • Scarb2 protein, rat