LAPTM4B controls the sphingolipid and ether lipid signature of small extracellular vesicles

Biochim Biophys Acta Mol Cell Biol Lipids. 2021 Feb;1866(2):158855. doi: 10.1016/j.bbalip.2020.158855. Epub 2020 Nov 10.

Abstract

Lysosome Associated Protein Transmembrane 4B (LAPTM4B) is a four-membrane spanning ceramide interacting protein that regulates mTORC1 signaling. Here, we show that LAPTM4B is sorted into intraluminal vesicles (ILVs) of multivesicular endosomes (MVEs) and released in small extracellular vesicles (sEVs) into conditioned cell culture medium and human urine. Efficient sorting of LAPTM4B into ILV membranes depends on its third transmembrane domain containing a sphingolipid interaction motif (SLim). Unbiased lipidomic analysis reveals a strong enrichment of glycosphingolipids in sEVs secreted from LAPTM4B knockout cells and from cells expressing a SLim-deficient LAPTM4B mutant. The altered sphingolipid profile is accompanied by a distinct SLim-dependent co-modulation of ether lipid species. The changes in the lipid composition of sEVs derived from LAPTM4B knockout cells is reflected by an increased stability of membrane nanodomains of sEVs. These results identify LAPTM4B as a determinant of the glycosphingolipid profile and membrane properties of sEVs.

Keywords: Ether lipids; Exosomes; Extracellular vesicles; Glycosphingolipids; Membrane nanodomains; Sphingolipids.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Endosomes / metabolism
  • Exosomes / metabolism*
  • Gene Knockout Techniques
  • Glycosphingolipids / metabolism*
  • Humans
  • Lipid Metabolism
  • Lipidomics
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Oncogene Proteins / genetics
  • Oncogene Proteins / metabolism*

Substances

  • Glycosphingolipids
  • LAPTM4B protein, human
  • Membrane Proteins
  • Oncogene Proteins