Lysophosphatidylcholine plays an essential role in the mitogenic effect of oxidized low density lipoprotein on murine macrophages.
We previously demonstrated that the growth of starch-induced murine macrophages was stimulated by modified low density lipoproteins, such as oxidized low density lipoprotein (Ox-LDL) and acetylated low density lipoprotein (acetyl-LDL), and that the mitogenic effect of Ox-LDL was much greater than that of acetyl-LDL (Yui, S., Sasaki, T., Miyazaki, A., Horiuchi, S., and Yamazaki, M. (1993) Arterioscler. Thromb. 13, 331-337). The present study was undertaken to elucidate the factor(s) that are involved in this growth-stimulating effect of Ox-LDL. The growth-stimulating effect of acetyl-LDL on murine resident macrophages was negligibly weak compared with that of Ox-LDL. However, the treatment of acetyl-LDL with phospholipase A2 led to an increase in lysophosphatidylcholine (lyso-PC) (75% of total phospholipids) and a concomitant increase in the mitogenic activity of acetyl-LDL. In contrast, cell-free incubation of Ox-LDL with high density lipoprotein resulted in a decrease in lyso-PC content and a concomitant loss of growth-stimulating activity. These results suggest that lyso-PC may play an essential role in the mitogenic activity of Ox-LDL.
Sakai
M
M
Department of Biochemistry, Kumamoto University School of Medicine, Japan.
Miyazaki
A
A
Hakamata
H
H
Sasaki
T
T
Yui
S
S
Yamazaki
M
M
Shichiri
M
M
Horiuchi
S
S
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D066298:In Vitro Techniques; D008075:Lipoproteins, HDL / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000494:pharmacology*; D008244:Lysophosphatidylcholines / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000166:cytology* / Q000187:drug effects; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D010084:Oxidation-Reduction; D010741:Phospholipases A / Q000494:pharmacology; D054467:Phospholipases A2
D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008244:Lysophosphatidylcholines; C032629:acetyl-LDL; D010741:Phospholipases A; D054467:Phospholipases A2