title: PI3KC2α, a class II PI3K, is required for dynamin-independent internalization pathways.
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.
authors.affiliation: Biotech Research and Innovation Centre, BRIC, University of Copenhagen, Ole Maaløes Vej 5, DK2200 Copenhagen, Denmark.
authors.forename: Claudia
authors.initials: C
authors.lastname: Krag
authors.forename: Emily Kim
authors.initials: EK
authors.lastname: Malmberg
authors.forename: Anna Elisabetta
authors.initials: AE
authors.lastname: Salcini
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000378:metabolism; D001692:Biological Transport; D018957:CD59 Antigens / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D004167:Diphtheria Toxin / Q000378:metabolism*; D015536:Down-Regulation; D034281:Dynamins / Q000378:metabolism; D004705:Endocytosis; D011992:Endosomes; D020868:Gene Silencing; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors; D018957:CD59 Antigens; D004167:Diphtheria Toxin; D034281:Dynamins; D017261:Glycosylphosphatidylinositols; D019869:Phosphatidylinositol 3-Kinases; D033921:Vesicular Transport Proteins; C093846:early endosome antigen 1; C546621:PIK3C2A protein, human