Beta-migrating very low density lipoproteins induce foam cell formation in mouse mesangial cells.

To elucidate whether beta-migrating very low density lipoproteins (beta-VLDL) induce foam cell formation in mesangial cells or not, surface binding and foam cell formation with P-VLDL were studied in mouse mesangial cells. Specific binding kinetics for beta-VLDL and low density lipoproteins (LDL) on the mesangial cells were observed with K-d=3.8 and 13.7 mu g/ml, and B-max=65.9 and 71.9 ng/mg cell protein at 4 degrees C, respectively. The binding of beta-VLDL was inhibited by excess amounts of LDL or beta-VLDL, but not by acetyl-low density lipoproteins. Ligand blotting using beta-VLDL or LDL and immunoblotting using anti-human LDL receptor monoclonal antibody detected the same apparent single protein (approx, 130 kDa). Incorporation of [C-14]oleate into cholesteryl ester in mouse mesangial cells was enhanced by beta-VLDL to S-fold higher than that by LDL, and it was inhibited by chloroquine or anti-human LDL receptor monoclonal antibody. The light microscopic findings also demonstrated that cholesteryl ester deposition increased in these cells incubated with beta-VLDL, but not with LDL. In conclusion, beta-VLDL was specifically taken up by receptor-mediated endocytosis in mouse mesangial cells through LDL receptors, resulting in foam cell formation.