A SPOPL/Cullin-3 ubiquitin ligase complex regulates endocytic trafficking by targeting EPS15 at endosomes

Elife. 2016 Mar 23:5:e13841. doi: 10.7554/eLife.13841.

Abstract

Cullin-3 (CUL3)-based ubiquitin ligases regulate endosome maturation and trafficking of endocytic cargo to lysosomes in mammalian cells. Here, we report that these functions depend on SPOPL, a substrate-specific CUL3 adaptor. We find that SPOPL associates with endosomes and is required for both the formation of multivesicular bodies (MVBs) and the endocytic host cell entry of influenza A virus. In SPOPL-depleted cells, endosomes are enlarged and fail to acquire intraluminal vesicles (ILVs). We identify a critical substrate ubiquitinated by CUL3-SPOPL as EPS15, an endocytic adaptor that also associates with the ESCRT-0 complex members HRS and STAM on endosomes. Indeed, EPS15 is ubiquitinated in a SPOPL-dependent manner, and accumulates with HRS in cells lacking SPOPL. Together, our data indicates that a CUL3-SPOPL E3 ubiquitin ligase complex regulates endocytic trafficking and MVB formation by ubiquitinating and degrading EPS15 at endosomes, thereby influencing influenza A virus infection as well as degradation of EGFR and other EPS15 targets.

Keywords: CUL3; EGFR; EPS15; SPOPL; biochemistry; cell biology; endocytosis; human; influenza A virus.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Vesicular Transport / metabolism*
  • Biological Transport
  • Calcium-Binding Proteins / metabolism*
  • Cell Line
  • Cullin Proteins / metabolism*
  • Endocytosis*
  • Endosomes / metabolism*
  • Humans
  • Influenza A virus / physiology
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Virus Internalization

Substances

  • Adaptor Proteins, Vesicular Transport
  • CUL3 protein, human
  • Calcium-Binding Proteins
  • Cullin Proteins
  • Eps15 protein, rat
  • Intracellular Signaling Peptides and Proteins
  • SPOPL protein, human