title: cPLA2α and EHD1 interact and regulate the vesiculation of cholesterol-rich, GPI-anchored, protein-containing endosomes.
abstract: The lipid modifier phospholipase A2 catalyzes the hydrolysis of phospholipids to inverted-cone-shaped lysophospholipids that contribute to membrane curvature and/or tubulation. Conflicting findings exist regarding the function of cytosolic phospholipase A2 (cPLA2) and its role in membrane regulation at the Golgi and early endosomes. However, no studies addressed the role of cPLA2 in the regulation of cholesterol-rich membranes that contain glycosylphosphatidylinositol-anchored proteins (GPI-APs). Our studies support a role for cPLA2α in the vesiculation of GPI-AP-containing membranes, using endogenous CD59 as a model for GPI-APs. On cPLA2α depletion, CD59-containing endosomes became hypertubular. Moreover, accumulation of lysophospholipids induced by a lysophospholipid acyltransferase inhibitor extensively vesiculated CD59-containing endosomes. However, overexpression of cPLA2α did not increase the endosomal vesiculation, implying a requirement for additional factors. Indeed, depletion of the "pinchase" EHD1, a C-terminal Eps15 homology domain (EHD) ATPase, also induced hypertubulation of CD59-containing endosomes. Furthermore, EHD1 and cPLA2α demonstrated in situ proximity (<40 nm) and interacted in vivo. The results presented here provide evidence that the lipid modifier cPLA2α and EHD1 are involved in the vesiculation of CD59-containing endosomes. We speculate that cPLA2α induces membrane curvature and allows EHD1, possibly in the context of a complex, to sever the curved membranes into vesicles.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA.
authors.forename: Bishuang
authors.initials: B
authors.lastname: Cai
authors.forename: Steve
authors.initials: S
authors.lastname: Caplan
authors.forename: Naava
authors.initials: N
authors.lastname: Naslavsky
mesh_terms: D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism; D008841:Actin Cytoskeleton / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000813:Anilides; D001692:Biological Transport; D018957:CD59 Antigens / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism; D034285:Dynamin II / Q000378:metabolism; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D058851:GPI-Linked Proteins / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D049452:Green Fluorescent Proteins / Q000378:metabolism; D054513:Group IV Phospholipases A2 / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D060588:LIM Domain Proteins / Q000378:metabolism; D008840:Microfilament Proteins; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism; D006899:Mixed Function Oxygenases; D011485:Protein Binding; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D022161:Transport Vesicles / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism*; D000096985:Calponins
chemical_list: D008243:1-Acylglycerophosphocholine O-Acyltransferase; D048868:Adaptor Proteins, Signal Transducing; D000813:Anilides; D018957:CD59 Antigens; D002784:Cholesterol; D003598:Cytoskeletal Proteins; D034285:Dynamin II; D058851:GPI-Linked Proteins; D049452:Green Fluorescent Proteins; D054513:Group IV Phospholipases A2; D060588:LIM Domain Proteins; D008840:Microfilament Proteins; D006899:Mixed Function Oxygenases; D011993:Recombinant Fusion Proteins; D033921:Vesicular Transport Proteins; C120700:EHD1 protein, human; C051590:CD59 protein, human; C069304:PD 128042; C455272:MICAL1 protein, human; D000096985:Calponins