Acetyl-low density lipoprotein receptors on rat mesangial cells.
To elucidate whether mesangial cells have any scavenger functions for modified lipoproteins, surface binding and cholesteryl ester (CE) formation by acetyl-low density lipoproteins (acetyl-LDL) have been studied in cultured rat renal mesangial cells. Specific binding kinetics for acetyl-LDL were observed with Kd = 28.3 micrograms/ml and Bmax = 1.1 ng/micrograms cell protein at 0 degrees C. The fluorescence microscopic finding demonstrated the enhanced uptake of DiI-acetyl-LDL in mesangial cells. Incorporation of [14C]oleate into CE was enhanced to 6-fold by loading 30 micrograms/ml of acetyl-LDL on 10 micrograms/ml of [14C]oleate-bovine serum albumin conjugate as compared with the control without lipoproteins (P < 0.05). The CE formation was completely inhibited by chloroquine. The light microscopic finding demonstrated the increased CE deposition by acetyl-LDL, resulting in foam cell formation. These results indicate biochemically and morphologically that the mesangial cells take up acetyl-LDL by receptor-mediated endocytosis, and that cholesterols in acetyl-LDL are converted to CE, resulting in an increased cellular cholesterol content. In conclusion, mesangial cells may have a scavenger function similar to macrophages.
Department of Metabolic Medicine, Kumamoto University School of Medicine, Japan.
K
K
Suzaki
S
S
Kobori
M
M
Ide
T
T
Sasahara
M
M
Sakai
T
T
Toyonaga
M
M
Shinohara
A
A
Miyazaki
S
S
Horiuchi
H
H
Takeda
D000818:Animals; D015815:Cell Adhesion Molecules; D002478:Cells, Cultured; D002788:Cholesterol Esters / Q000378:metabolism; D005920:Glomerular Mesangium / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism; D051381:Rats; D011973:Receptors, LDL / Q000378:metabolism*; D051116:Receptors, Scavenger
D015815:Cell Adhesion Molecules; D002788:Cholesterol Esters; D008077:Lipoproteins, LDL; D011973:Receptors, LDL; D051116:Receptors, Scavenger