Modified low density lipoprotein delivers substrate for ceramide formation and stimulates the sphingomyelin-ceramide pathway in human macrophages.
Exposure of human blood monocytes derived macrophages to modified (oxidized or acetylated) LDL induced a approximately 40% elevation (60 pmol/10(6) cells) of the endogenous level of the sphingolipid ceramide. A rise of both neutral and acidic SMase activity was found after treatment with oxidized LDL (250 and 80%), while addition of acLDL stimulated only the neutral enzyme (280%). Sphingo(phospho)lipids from LDL were transferred to the cell membrane and distributed into intracellular compartments as observed with acLDL containing BODIPY-FL-C5-SM. Quantitation of ceramide after the addition of [3H-N-acetyl]- or BODIPY-FL-C5-SM-labeled modified LDL (27 microg/ml) to the cell culture medium indicated that approximately 210 pmol CA/10(6) cells was generated from exogenous (ox/acLDL) SM. These results demonstrate a stimulation of the sphingomyelin-ceramide pathway by modified LDL utilizing primarily exogenous (LDL-derived) substrate and suggest that the effects of modified LDL are at least partially due to an increased level of the messenger ceramide.
Kinscherf
R
R
Pharmazeutisch-Chemisches Institut, Universität Heidelberg, Germany.
Claus
R
R
Deigner
H P
HP
Nauen
O
O
Gehrke
C
C
Hermetter
A
A
Russwurm
S
S
Daniel
V
V
Hack
V
V
Metz
J
J
D001896:Boron Compounds / Q000737:chemistry; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D008074:Lipoproteins / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008297:Male; D010740:Phospholipases / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism*; D014316:Tritium
C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D002518:Ceramides; D005456:Fluorescent Dyes; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D013109:Sphingomyelins; D014316:Tritium; D010740:Phospholipases