title: Pathological levels of glucosylceramide change the biophysical properties of artificial and cell membranes.
abstract: Glucosylceramide (GlcCer) plays an active role in the regulation of various cellular events. Moreover, GlcCer is also a key modulator of membrane biophysical properties, which might be linked to the mechanism of its biological action. In order to understand the biophysical implications of GlcCer on membranes of living cells, we first studied the effect of GlcCer on artificial membranes containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), sphingomyelin (SM) and cholesterol (Chol). Using an array of biophysical methods, we demonstrate that at lower GlcCer/Chol ratios, GlcCer stabilizes SM/Chol-enriched liquid-ordered domains. However, upon decreasing the Chol content, GlcCer significantly increased membrane order through the formation of gel domains. Changes in pH disturbed the packing properties of GlcCer-containing membranes, leading to an increase in membrane fluidity and reduced membrane electronegativity. To address the biophysical impact of GlcCer in biological membranes, studies were performed in wild type and in fibroblasts treated with conduritol-B-epoxide (CBE), which causes intracellular GlcCer accumulation, and in fibroblasts from patients with type I Gaucher disease (GD). Decreased membrane fluidity was observed in cells containing higher levels of GlcCer, such as in CBE-treated and GD cells. Together, we demonstrate that elevated GlcCer levels change the biophysical properties of cellular membranes, which might compromise membrane-associated cellular events and be of relevance for understanding the pathology of diseases, such as GD, in which GlcCer accumulates at high levels.
authors.affiliation: iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal. lianacsilva@ff.ulisboa.pt and Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal and Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Ana R P
authors.initials: AR
authors.lastname: Varela
authors.affiliation: iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal. lianacsilva@ff.ulisboa.pt and Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal and Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Ana E
authors.initials: AE
authors.lastname: Ventura
authors.affiliation: iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal. lianacsilva@ff.ulisboa.pt and Centro de Química e Bioquímica, DQB, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Carreira
authors.affiliation: Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: Aleksander
authors.initials: A
authors.lastname: Fedorov
authors.affiliation: Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Anthony H
authors.initials: AH
authors.lastname: Futerman
authors.affiliation: Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: Manuel
authors.initials: M
authors.lastname: Prieto
authors.affiliation: iMed.ULisboa - Research Institute for Medicines, Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal. lianacsilva@ff.ulisboa.pt.
authors.forename: Liana C
authors.identifier: http://orcid.org/0000-0003-1311-0770
authors.initials: LC
authors.lastname: Silva
mesh_terms: D055592:Biophysical Phenomena; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002784:Cholesterol / Q000737:chemistry*; D005963:Glucosylceramides / Q000737:chemistry*; D010713:Phosphatidylcholines; D013109:Sphingomyelins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005963:Glucosylceramides; D010713:Phosphatidylcholines; D013109:Sphingomyelins; D002784:Cholesterol; C028694:1-palmitoyl-2-oleoylphosphatidylcholine