Induction of ganglioside biosynthesis and neurite outgrowth of primary cultured neurons by L-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol.
We reported previously that stereoisomers of 1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), the D-threo and L-threo forms, exerted inhibitory and stimulatory effects on glycosphingolipid (GSL) biosynthesis in B16 melanoma cells, respectively. In the present study, the primary cultured rat neocortical explants were treated with L- or D-threo-PDMP. These isomers exhibited opposite effects on neurite outgrowth: D-PDMP was inhibitory at concentrations ranging from 5 to 20 microM, whereas L-PDMP was stimulatory over the same concentration range, and the maximal effect was observed at 10-15 microM. Rat neocortical explants were doubly labeled with [14C]serine and [3H]galactose at 15 microM L- or D-PDMP. L-PDMP increased the incorporations of both labels into sphinganine, sphingosine, ceramide, sphingomyelin, neutral GSLs, and gangliosides, whereas D-PDMP inhibited the glucosylation of ceramide resulting in a reduction of ganglioside biosynthesis and accumulation of precursors of glucosylceramide, ceramide, and sphingomyelin. To clarify the stimulatory effect of L-PDMP on GSL biosynthesis, serine palmitoyltransferase, sphingosine N-acyltransferase, glucosylceramide synthase, lactosylceramide synthase, GM3 synthase, and GD3 synthase were quantified in cell lysates of explants pretreated with this agent. Serine palmitoyltransferase was fully activated up to 150% of the control. Furthermore, marked increases in the activities of lactosylceramide synthase (200%), GM3 synthase (240%), and GD3 synthase (300%) were observed. These results suggest that the neurotrophic action of L-PDMP may be ascribable to its stimulatory effect on the biosynthesis of GSLs, especially that of gangliosides.
Usuki
S
S
Tokyo Research Institute, Seikagaku Corporation, Japan.
Hamanoue
M
M
Kohsaka
S
S
Inokuchi
J
J
D000818:Animals; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005690:Galactose / Q000378:metabolism; D005732:Gangliosides / Q000096:biosynthesis*; D006028:Glycosphingolipids / Q000096:biosynthesis*; D006801:Humans; D007700:Kinetics; D009025:Morpholines / Q000494:pharmacology*; D016501:Neurites / Q000502:physiology* / Q000648:ultrastructure; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011247:Pregnancy; D011865:Radioisotope Dilution Technique; D051381:Rats; D017208:Rats, Wistar; D012694:Serine / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D013237:Stereoisomerism; D014316:Tritium
D002250:Carbon Radioisotopes; D002518:Ceramides; D004791:Enzyme Inhibitors; D005732:Gangliosides; D006028:Glycosphingolipids; D009025:Morpholines; D013109:Sphingomyelins; D014316:Tritium; D012694:Serine; C033110:RV 538; D013110:Sphingosine; C005682:safingol; D005690:Galactose