title: On the presence of C2-ceramide in mammalian tissues: possible relationship to etherphospholipids and phosphorylation by ceramide kinase.
abstract: C(2)-ceramide (N-acetyl-sphingenine) is often used as an analog to study ceramide-mediated cellular processes. According to Lee et al. [J. Biol. Chem. 271 (1996), 209-217], C(2)-ceramide is formed by an acetyl transfer from platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) to sphingenine. To substantiate these unconfirmed findings, we (i) developed a method to quantify C(2)-ceramide and (ii) analyzed C(2)-ceramide levels in Pex5(-/-) mice, a model for Zellweger syndrome, in which the synthesis of ether lipids such as PAF is impaired. The presence of C(2)-ceramide could be established in brain (+/-10 pmol/g) and liver (+/-25 pmol/g) from control mice, and was approximately 5000-fold less than the main long-chain ceramide species. In Pex5(-/-) mice, C(2)-ceramide levels did not differ significantly compared to control tissues. Given the presence of a ceramide kinase in mammals, phosphorylation of C(2)-ceramide by human ceramide kinase (HsCERK) was tested. C(2)-ceramide appears to be a good substrate when albumin is used as carrier. In CHO cells overexpressing HsCERK, phosphorylation of exogenously added C(2)-ceramide could also be demonstrated. Our data indicate that C(2)-ceramide is present in mammalian tissues and can be converted to C(2)-ceramide-1-phosphate, in addition to other documented metabolic alterations, but does not seem to be linked to ether lipid metabolism.
authors.affiliation: Katholieke Universiteit Leuven, Departement Moleculaire Celbiologie, Afdeling Farmacologie, B-3000 Leuven, Belgium.
authors.forename: Helena
authors.initials: H
authors.lastname: Van Overloop
authors.forename: Yves
authors.initials: Y
authors.lastname: Denizot
authors.forename: Myriam
authors.initials: M
authors.lastname: Baes
authors.forename: Paul P
authors.initials: PP
authors.lastname: Van Veldhoven
mesh_terms: D000818:Animals; D016466:CHO Cells; D002518:Ceramides / Q000302:isolation & purification / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D051379:Mice; D010742:Phospholipid Ethers / Q000378:metabolism*; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism
chemical_list: D002518:Ceramides; C064769:N-acetylsphingosine; D010742:Phospholipid Ethers; D010972:Platelet Activating Factor; C065576:ceramide 1-phosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C066324:ceramide kinase; D013110:Sphingosine