Moesin regulates the trafficking of nascent clathrin-coated vesicles

J Biol Chem. 2009 Jan 23;284(4):2419-34. doi: 10.1074/jbc.M805311200. Epub 2008 Nov 30.

Abstract

Clathrin-coated vesicles are responsible for the trafficking of several internalized biological cargos. We have observed that the endogenous F-actin-linker moesin co-distributes with constitutive components of clathrin-coated structures. Total internal reflection fluorescence microscopy studies have shown that short interference RNA of moesin enhances the lateral movement of clathrin-coated structures and provokes their abnormal clustering. The aggregation of clathrin-coated structures has also been observed in cells overexpressing N-moesin, a dominant-negative construct unable to bind to F-actin. Only overexpressed moesin constructs with an intact phosphatidylinositol 4,5-bisphosphate-binding domain co-distribute with clathrin-coated structures. Hence, this N-terminal domain is mostly responsible for moesin/clathrin-coated structure association. Biochemical endosome fractioning together with total internal reflection fluorescence microscopy comparative studies, between intact cells and plasma-membrane sheets, indicate that moesin knockdown provokes the accumulation of endocytic rab5-clathrin-coated vesicles carrying the transferrin receptor. The altered trafficking of these endocytic rab5-clathrin-coated vesicles accounts for a transferrin receptor recycling defect that reduces cell-surface expression of the transferrin receptor and increases the amount of sequestered transferrin ligand. Therefore, we propose that moesin is a clathrin-coated vesicle linker that drives cargo trafficking and acts on nascent rab5-clathrin-coated vesicles by simultaneously binding to clathrin-coated vesicle-associated phosphatidylinositol 4,5-bisphosphate and actin cytoskeleton. Hence, functional alterations of moesin may be involved in pathological disorders associated with clathrin-mediated internalization or receptor recycling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Clathrin-Coated Vesicles / metabolism*
  • HeLa Cells
  • Humans
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Protein Binding
  • Protein Transport
  • RNA, Small Interfering / genetics
  • Receptors, Transferrin / metabolism
  • Transferrin / metabolism

Substances

  • Microfilament Proteins
  • RNA, Small Interfering
  • Receptors, Transferrin
  • Transferrin
  • moesin