PI3KC2α, a class II PI3K, is required for dynamin-independent internalization pathways

J Cell Sci. 2010 Dec 15;123(Pt 24):4240-50. doi: 10.1242/jcs.071712. Epub 2010 Nov 16.

Abstract

Increasing evidence indicates that cellular uptake of several molecules can occur independently of functional dynamin, but the molecular players that regulate dynamin-independent endocytosis and the subsequent trafficking steps are still largely unknown. A survival-based short-hairpin (sh) RNA screen using a cell line expressing a diphtheria toxin receptor (DTR, officially known as HBEGF) anchored to GPI (DTR-GPI), which internalizes diphtheria toxin (DT, officially known as DTX) in a dynamin-independent manner, identified PI3KC2α, a class II phosphoinositide 3-kinase (PI3K), as a specific regulator of dynamin-independent DT internalization. We found that the internalization of several proteins that enter the cell through dynamin-independent pathways led to a relocalization of PI3KC2α to cargo-positive vesicles. Furthermore, downregulation of PI3KC2α impaired internalization of CD59 as well as fluid-phase endocytosis. Our data suggest a general role for PI3KC2α in regulating physiologically relevant dynamin-independent internalization pathways by recruiting early endosome antigen 1 (EEA1) to vesicular compartments, a step required for the intracellular trafficking of vesicles generated by dynamin-independent endocytic pathways.

Publication types

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

MeSH terms

  • ADP-Ribosylation Factor 6
  • ADP-Ribosylation Factors / metabolism
  • Biological Transport
  • CD59 Antigens / metabolism
  • Cell Membrane / metabolism
  • Diphtheria Toxin / metabolism*
  • Down-Regulation
  • Dynamins / metabolism
  • Endocytosis*
  • Endosomes
  • Gene Silencing
  • Glycosylphosphatidylinositols / metabolism
  • HeLa Cells
  • Humans
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Vesicular Transport Proteins / metabolism

Substances

  • ADP-Ribosylation Factor 6
  • CD59 Antigens
  • Diphtheria Toxin
  • Glycosylphosphatidylinositols
  • Vesicular Transport Proteins
  • early endosome antigen 1
  • PIK3C2A protein, human
  • ADP-Ribosylation Factors
  • Dynamins