Missing-in-metastasis protein downregulates CXCR4 by promoting ubiquitylation and interaction with small Rab GTPases

J Cell Sci. 2017 Apr 15;130(8):1475-1485. doi: 10.1242/jcs.198937. Epub 2017 Mar 6.

Abstract

Surface expression of chemokine receptor CXCR4 is downregulated by missing-in-metastasis protein (MIM; also known as MTSS1), a member of the inverse BAR (I-BAR)-domain protein family that recognizes and generates membranes with negative curvature. Yet, the mechanism for the regulation is unknown. Here, we show that MIM forms a complex with CXCR4 by binding to E3 ubiquitin ligase AIP4 (also known as ITCH) in response to stromal cell-derived factor 1 (SDF-1; also known as CXCL12). Overexpression of MIM promoted CXCR4 ubiquitylation, inhibited cellular response to SDF-1, caused accumulation and aggregation of multivesicular bodies (MVBs) in the cytoplasm, and promoted CXCR4 sorting into MVBs in a manner depending on binding to AIP4. In response to SDF-1, MIM also bound transiently to the small GTPase Rab5 at 5 min and to Rab7 at 30 min. Binding to Rab7 requires an N-terminal coiled-coil motif, deletion of which abolished MIM-mediated MVB formation and CXCR4 internalization. Our results unveil a previously unknown property of MIM that establishes the linkage of protein ubiquitylation with Rab-guided trafficking of CXCR4 in endocytic vesicles.

Keywords: AIP4; CXCR4; MIM; MVBs; Rab7; Ubiquitylation.

Publication types

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

MeSH terms

  • Animals
  • Chemokine CXCL12 / metabolism*
  • Down-Regulation*
  • Endocytosis / genetics
  • Endosomes / metabolism
  • HeLa Cells
  • Humans
  • Mice
  • Mice, Knockout
  • Microfilament Proteins / genetics
  • Microfilament Proteins / immunology
  • Microfilament Proteins / metabolism*
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / immunology
  • Neoplasm Proteins / metabolism*
  • Protein Binding
  • Protein Transport
  • Receptors, CXCR4 / metabolism*
  • Transport Vesicles / metabolism
  • Ubiquitination
  • rab GTP-Binding Proteins / metabolism

Substances

  • CXCL12 protein, human
  • CXCR4 protein, human
  • CXCR4 protein, mouse
  • Chemokine CXCL12
  • Microfilament Proteins
  • Mtss1 protein, mouse
  • Neoplasm Proteins
  • Receptors, CXCR4
  • rab GTP-Binding Proteins