Synthesis of sphingomyelin by oligodendrocytes--how and where?
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.
Laboratory of Veterinary Biochemistry, Utrecht University, Netherlands.
J P
JP
Vos
M L
ML
Giudici
P
P
van der Bijl
M
M
Lopes-Cardozo
D000818:Animals; D002451:Cell Compartmentation; D009836:Oligodendroglia / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013109:Sphingomyelins / Q000096:biosynthesis*; D013116:Spinal Cord / Q000378:metabolism* / Q000648:ultrastructure
D013109:Sphingomyelins