title: Biophysical properties of novel 1-deoxy-(dihydro)ceramides occurring in mammalian cells.
abstract: Ceramides and dihydroceramides are N-acyl derivatives of sphingosine and sphinganine, respectively, which are the major sphingoid-base backbones of mammals. Recent studies have found that mammals, like certain other organisms, also produce 1-deoxy-(dihydro)ceramides (1-deoxyDHCers) that contain sphingoid bases lacking the 1-hydroxyl- or 1-hydroxymethyl- groups. The amounts of these compounds can be substantial-indeed, we have found comparable levels of 1-deoxyDHCers and ceramides in RAW 264.7 cells maintained in culture. The biophysical properties of 1-deoxyDHCers have not yet been reported, although these lipids might play important roles in normal cell regulation and in the pathology of diseases in which they are elevated, such as hereditary sensory autonomic neuropathies or diabetes. This study uses several approaches, including surface-pressure measurements, differential scanning calorimetry, and confocal microscopy, to study the behavior of 1-deoxyDHCers of different N-acyl-chain lengths and their interaction with sphingomyelin (SM). The thermotropic behaviors of 1-deoxyDHCers alone and in mixtures with SM are described, together with their interactions in monolayers and giant unilamellar vesicles. The gel-fluid transition temperatures of the pure compounds increase in the order 1-deoxyceramide < ceramide ≈ 1-deoxyDHCer < 1-(deoxymethyl)DHCer. In general, canonical ceramides are more miscible with SM in bilayers than are 1-deoxyceramides, and 1-(deoxymethyl)DHCers are the most hydrophobic among them, not even capable of forming monolayers at the air-water interface. Thus, these properties suggest that 1-deoxyDHCer can influence the properties of cellular membranes in ways that might affect biological function/malfunction.
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain.
authors.forename: Noemi
authors.initials: N
authors.lastname: Jiménez-Rojo
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Sot
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain.
authors.forename: Jon V
authors.initials: JV
authors.lastname: Busto
authors.affiliation: Avanti Polar Lipids, Alabaster, Alabama.
authors.forename: Walt A
authors.initials: WA
authors.lastname: Shaw
authors.affiliation: School of Biology and Petite Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Duan
authors.affiliation: School of Biology and Petite Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia.
authors.forename: Alfred H
authors.initials: AH
authors.lastname: Merrill
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Alonso
authors.affiliation: Unidad de Biofísica (CSIC, UPV/EHU), and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain. Electronic address: felix.goni@ehu.es.
authors.forename: Félix M
authors.initials: FM
authors.lastname: Goñi
mesh_terms: D000818:Animals; D002460:Cell Line; D002518:Ceramides / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D053835:Unilamellar Liposomes / Q000737:chemistry
chemical_list: D002518:Ceramides; D053835:Unilamellar Liposomes; C109343:dihydroceramide