Synthesis of sphingomyelin by oligodendrocytes—how and where?

• Published in: Journal of lipid mediators and cell signalling Vol. 14; no. 1; pp. 313 - 319
• Main Authors: Vos, Jan P., Giudici, M.Luisa, van der Bijl, Petra, Lopes-Cardozo, Matthijs
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-09-1996
• Subjects: Animals; Cell Compartmentation; Fluorescent ceramide analogs; Oligodendroglia - metabolism; Oligodendroglia - ultrastructure; Rat spinal cord oligodendrocytes; Rats; Rats, Wistar; Sphingomyelin biosynthesis in the CNS; Sphingomyelin synthase in myelin; Sphingomyelins - biosynthesis; Spinal Cord - metabolism; Spinal Cord - ultrastructure; PC, phosphatidylcholine; MMPEA, monomethyl-phospho-ethanolamine; SM, sphingomyelin; OC, oligodendrocytes; PE, phosphatidylethanolamine; Fluorescent ceramide analogs; PS, phosphatidylserine; BFA, brefeldin A; LRh, N-lissamine rhodamine; DMPEA, dimethyl-phospho-ethanolamine; Sphingomyelin biosynthesis in the CNS; Rat spinal cord oligodendrocytes; Sphingomyelin synthase in myelin; NBD, N-(7-nitrobenz-2-oxo-1,3-diazol-4-yl)
• ISSN: 0929-7855
• DOI: 10.1016/0929-7855(96)00540-8

Sphingomyelin (SM) biosynthesis in cultured oligodendrocytes (OC) was evaluated: (i) with [
14C] tracers (choline, ethanolamine, serine) to pinpoint the major metabolic routes; (ii) with fluorescent and truncated, radiolabeled ceramide analogs to determine the relative activities of SM-synthase in intra- and extra-Golgi compartments of OC. In contrast to a general contention in the literature that SM synthase is absent from the brain, our data show that (choline → CDP-choline → phosphatidylcholine (PC) → SM) is the major anabolic route with only a minor contribution to PC via methylation of phosphatidylethanolamine (PE). SM synthase activity was found to be equally divided between intra- and extra-Golgi compartments of OC. Moreover, significant SM-synthase activity was recovered in purified myelin preparations. Our results shed new light on the possible involvement of sphingolipid-derived mediators in myelination.