Two independent macrophage receptors for acetylated high-density lipoprotein.
We previously demonstrated that acetylated human high-density lipoprotein (acetyl-HDL) was recognized by a scavenger receptor of rat sinusoidal liver cells (Murakami, M., Horiuchi, S., Takata, K. and Morino, Y. (1987) J. Biochem. (Tokyo) 101, 729-741). The present study describes the interaction of acetyl-HDL with rat peritoneal macrophages in vitro. Acetylation of HDL enhanced its cell-association by 2-fold and cellular degradation by > 25-fold. The cell-association of [125I]acetyl-HDL was effectively inhibited by unlabeled acetyl-HDL (> 85%), whereas the inhibition by HDL or acetylated human low-density lipoprotein (acetyl-LDL) was partial (60% and 50%, respectively). However, when both HDL and acetyl-LDL were present, the cell-association of [125I]acetyl-HDL was effectively inhibited by > 80%, a level identical or closely similar to that by acetyl-HDL. The cellular degradation of [125I]acetyl-HDL was effectively suppressed by acetyl-LDL whereas the effect of HDL was much weaker. These findings indicate that acetyl-HDL is endocytosed by both the HDL receptor and the scavenger receptor for acetyl-LDL in which the ligands bound to the latter might be subjected to lysosomal degradation.
Department of Biochemistry, Kumamoto University School of Medicine, Japan.
A
A
Miyazaki
M
M
Sakai
E
E
Yamaguchi
Y
Y
Sakamoto
M
M
Shichiri
S
S
Horiuchi
D000107:Acetylation; D000818:Animals; D002352:Carrier Proteins; D002788:Cholesterol Esters / Q000032:analysis; D007457:Iodine Radioisotopes; D008075:Lipoproteins, HDL / Q000378:metabolism* / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000494:pharmacology; D008247:Lysosomes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D016601:RNA-Binding Proteins; D051381:Rats; D017208:Rats, Wistar; D011973:Receptors, LDL / Q000032:analysis; D018110:Receptors, Lipoprotein / Q000032:analysis*
D002352:Carrier Proteins; D002788:Cholesterol Esters; D007457:Iodine Radioisotopes; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D016601:RNA-Binding Proteins; D011973:Receptors, LDL; D018110:Receptors, Lipoprotein; C031616:high density lipoprotein receptors; C075197:high density lipoprotein binding protein