title: Functional characterization of enzymes catalyzing ceramide phosphoethanolamine biosynthesis in mice.
abstract: Besides bulk amounts of SM, mammalian cells produce small quantities of the SM analog ceramide phosphoethanolamine (CPE). Little is known about the biological role of CPE or enzymes responsible for CPE production. Heterologous expression studies revealed that SM synthase (SMS)2 is a bifunctional enzyme producing both SM and CPE, whereas SMS-related protein (SMSr) serves as monofunctional CPE synthase. Acute disruption of SMSr catalytic activity in cultured cells causes a rise in endoplasmic reticulum (ER) ceramides, fragmentation of ER exit sites, and induction of mitochondrial apoptosis. To address the relevance of CPE biosynthesis in vivo, we analyzed the tissue-specific distribution of CPE in mice and generated mouse lines lacking SMSr and SMS2 catalytic activity. We found that CPE levels were >300-fold lower than SM in all tissues examined. Unexpectedly, combined inactivation of SMSr and SMS2 significantly reduced, but did not eliminate, tissue-specific CPE pools and had no obvious impact on mouse development or fertility. While SMSr is widely expressed and serves as the principal CPE synthase in the brain, blocking its catalytic activity did not affect ceramide levels or secretory pathway integrity in the brain or any other tissue. Our data provide a first inventory of CPE species and CPE-biosynthetic enzymes in mammals.
authors: Molecular Genetics, Life, and Medical Sciences Institute University of Bonn, 53115 Bonn, Germany.
authors: Andreas
authors: A
authors: Bickert
authors: Molecular Genetics, Life, and Medical Sciences Institute University of Bonn, 53115 Bonn, Germany.
authors: Christina
authors: C
authors: Ginkel
authors: Molecular Cell Biology Division, Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany.
authors: Matthijs
authors: M
authors: Kol
authors: Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, 53115 Bonn, Germany.
authors: Katharina
authors: K
authors: vom Dorp
authors: Imaging Center Essen, Electron Microscopy Unit, University Hospital University of Duisburg-Essen, 45147 Essen, Germany.
authors: Holger
authors: H
authors: Jastrow
authors: Molecular Genetics, Life, and Medical Sciences Institute University of Bonn, 53115 Bonn, Germany.
authors: Joachim
authors: J
authors: Degen
authors: Departments of Agricultural, Food, and Nutritional Science, Molecular and Cell Biology of Lipids, University of Alberta, T6G 2S2 Edmonton, Canada.
authors: René L
authors: RL
authors: Jacobs
authors: Biochemistry, University of Alberta, T6G 2S2 Edmonton, Canada.
authors: Dennis E
authors: DE
authors: Vance
authors: Department of Molecular Biology, University of Duisburg-Essen, 45147 Essen, Germany.
authors: Elke
authors: E
authors: Winterhager
authors: Department of Anatomy and Cell Biology, SUNY Downstate Medical Center, Brooklyn, NY 11203.
authors: Xian-Cheng
authors: XC
authors: Jiang
authors: Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, 53115 Bonn, Germany.
authors: Peter
authors: P
authors: Dörmann
authors: Medical Biochemistry, Institute of Biomedicine, University of Helsinki, 00014 Helsinki, Finland.
authors: Pentti
authors: P
authors: Somerharju
authors: Molecular Cell Biology Division, Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany.
authors: Joost C M
authors: JC
authors: Holthuis
authors: Molecular Genetics, Life, and Medical Sciences Institute University of Bonn, 53115 Bonn, Germany.
authors: Klaus
authors: K
authors: Willecke
mesh_terms: D000818:Animals; D055162:Biocatalysis; D001921:Brain / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D020134:Catalytic Domain; D002470:Cell Survival; D004789:Enzyme Activation; D005091:Exons / Q000235:genetics; D017353:Gene Deletion; D015971:Gene Expression Regulation, Enzymologic; D008099:Liver / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009928:Organ Specificity; D050918:Phosphatidylethanolamine N-Methyltransferase / Q000378:metabolism; D017354:Point Mutation; D021381:Protein Transport; D013109:Sphingomyelins / Q000096:biosynthesis* / Q000378:metabolism; D017855:Transferases (Other Substituted Phosphate Groups) / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
chemical_list: D013109:Sphingomyelins; C060281:ceramide phosphoethanolamine; D050918:Phosphatidylethanolamine N-Methyltransferase; D017855:Transferases (Other Substituted Phosphate Groups); C543123:Sgms2 protein, mouse
keywords: brain lipids; enzyme inactivation; genetics; mass spectrometry; sphingolipids; sphingomyelin synthase; sphingomyelin synthase-related protein; sterile α motif domain-containing protein 8; transgenic mice