title: Fluorescent analogues of plasma membrane sphingolipids are sorted to different intracellular compartments in astrocytes; Harmful effects of chronic ethanol exposure on sphingolipid trafficking and metabolism.
abstract: Sphingolipids are basic constituents of cellular membranes and are essential for numerous functions such as intracellular signalling. They are transported along the exocytic and endocytic pathways in eukaryotic cells. After endocytosis, fluorescent-labelled sphingolipids are sorted to distinct intracellular organelles prior to recycling (via early/recycling endosomes) or degradation (late endosomes/lysosomes). Here we examine, in primary cultures of rat astrocytes, the internalisation routes followed by C(6)-NBD-glucosylceramide (NBD-GlcCer) and C(6)-NBD-sphingomyelin (NBD-SM) and the effects of ethanol on their endocytic trafficking. Endocytosed plasma membrane NBD-GlcCer and NBD-SM are diverted to the Golgi apparatus and lysosomes, respectively. These different internalisation pathways are maintained regardless of the differentiation stage of astrocytes. Chronic ethanol exposure did not alter this endocytic sorting, but delayed the internalisation of both NBD-sphingolipids. Moreover, ethanol also stimulated the in situ metabolism of NBD-ceramide to NBD-GlcCer and NBD-SM. We conclude that in rat astrocytes internalised plasma membrane NBD-sphingolipids are sorted to different subcellular compartments. The exposure to chronic ethanol perturbed the lipid endocytic process and stimulated the de novo synthesis of NBD-sphingolipids, shifting the balance of sphingolipid metabolism in favour of the sphingomyelin pathway.
authors.affiliation: Departament de Biologia Cellular i Anatomia Patològica, Facultat de Medicina, Universitat de Barcelona-IDIBAPS, C/ Casanova 143, E-08036 Barcelona, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Tomás
authors.forename: Juan M
authors.initials: JM
authors.lastname: Durán
authors.forename: Francisco
authors.initials: F
authors.lastname: Lázaro-Diéguez
authors.forename: Teresa
authors.initials: T
authors.lastname: Babià
authors.forename: Jaime
authors.initials: J
authors.lastname: Renau-Piqueras
authors.forename: Gustavo
authors.initials: G
authors.lastname: Egea
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology; D002451:Cell Compartmentation / Q000187:drug effects; D002454:Cell Differentiation; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002478:Cells, Cultured; D004705:Endocytosis / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology*; D005333:Fetus; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D013107:Sphingolipids / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors
chemical_list: D000911:Antibodies, Monoclonal; D005456:Fluorescent Dyes; D008563:Membrane Lipids; D011500:Protein Synthesis Inhibitors; D013107:Sphingolipids; D020126:Brefeldin A; D000431:Ethanol; D015739:Nocodazole