Sphingomyelin-metabolizing enzymes and protein kinase C activity in liver plasma membranes of rats fed with cholesterol-supplemented diet.
The effect of cholesterol-supplemented diet on the activities of rat liver plasma membrane sphingomyelin-metabolizing enzymes and protein kinase C was studied. Protein kinase C, phosphatidylcholine:ceramide-phosphocholine transferase, and phosphatidylethanolamine:ceramide-phosphoethanolamine transferase activities were found to increase continuously and almost in parallel during the experimental period on cholesterol diet (days 10, 20, and 30). Linear regression analysis showed a positive correlation between these activities with correlation coefficients r = 0.959 for protein kinase C and phosphatidylcholine:ceramide-phosphocholine transferase, and r = 0.998 for protein kinase C and phosphatidylethanolamine:ceramide-phosphoethanolamine transferase. On the other hand, protein kinase C activation does not correspond to sphingomyelinase activity changes. These data suggest that protein kinase C activation observed in cholesterol-enriched plasma membranes is due to increased production of diacylglycerol and increased acylation of sphingosine to ceramide.
Nikolova-Karakashian
M N
MN
Central Laboratory of Biophysics, Bulgarian Academy of Sciences, Sofia.
Gavrilova
N J
NJ
Petkova
D H
DH
Setchenska
M S
MS
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D002791:Cholesterol, Dietary / Q000494:pharmacology*; D004075:Diglycerides / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D010770:Phosphotransferases / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism*; D017855:Transferases (Other Substituted Phosphate Groups)
D002791:Cholesterol, Dietary; D004075:Diglycerides; D008565:Membrane Proteins; D013109:Sphingomyelins; D010770:Phosphotransferases; D011493:Protein Kinase C; D017855:Transferases (Other Substituted Phosphate Groups); C070185:phosphatidylethanolamine-ceramide phosphoethanolamine transferase; C019863:ceramide cholinephosphotransferase; D013108:Sphingomyelin Phosphodiesterase