title: Transbilayer asymmetry of phospholipids in the plasma membrane regulates exocytotic release in mast cells.
abstract: To investigate the role of the asymmetric distribution of phospholipids of the plasma membrane in exocytosis, we examined the effects of disruption of this asymmetrical distribution of lipids on exocytotic release from mast cells (RBL-2H3). Lipid scramblase, which is activated by divalent cations and catalyzes the transbilayer movement of phospholipids, was overexpressed in mast cells. Exogenous lipid scramblase was expressed in the plasma membrane and the cytoplasm. Activation of scramblase by divalent cations disrupted the asymmetrical distribution of phospholipids in the plasma membrane. Exocytotic release induced by calcium ionophore and phorbol ester was significantly inhibited in the cells transfected with wild-type scramblase. This inhibition was observed with time lag of about 5 min. Furthermore, when the asymmetric distribution of lipids was disrupted before induction of exocytosis, the inhibition of exocytotic release was obvious from the beginning without time lag. These results suggest that the asymmetric distribution of phospholipids in the plasma membrane plays an essential role in fusion between secretory granules and the plasma membrane. This finding also demonstrates that the transbilayer asymmetry of phospholipids regulates exocytosis and gives a new insight into the significance of lipid asymmetry in the plasma membrane.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Kato
authors.forename: Mamoru
authors.initials: M
authors.lastname: Nakanishi
authors.forename: Naohide
authors.initials: N
authors.lastname: Hirashima
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D002413:Cations, Divalent / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D005089:Exocytosis / Q000235:genetics; D016259:Genes, myc; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008345:Manganese / Q000494:pharmacology; D008407:Mast Cells / Q000737:chemistry* / Q000201:enzymology / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D051379:Mice; D010718:Phosphatidylserines / Q000378:metabolism; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D002352:Carrier Proteins; D002413:Cations, Divalent; D008051:Lipid Bilayers; D008565:Membrane Proteins; D010718:Phosphatidylserines; D049294:Phospholipid Transfer Proteins; D010743:Phospholipids; D008345:Manganese