The
very low density lipoprotein (
VLDL) receptor is a member of the
LDL receptor gene family and binds only
apoE-containing
lipoproteins. Although the
VLDL receptor has been shown to play an important role in the proliferation of vascular smooth muscle cells and the formation of foam cells as primary responses of
atherogenesis, its actual functions are still unclear. To understand the
biological roles of the
VLDL receptor in foam cell formation and cell growth, we tried to overexpress VLDL receptors in various cells. When COS-7 cells were transfected with an expression plasmid containing
VLDL receptor cDNA, cell growth was inhibited by overexpression of the receptor and this growth inhibition was
ligand-independent. The O-linked glycosylation region, but not the cytoplasmic domain, of the receptor appeared to be responsible for this growth inhibition. On the other hand,
VLDL receptor expression induced enhanced incorporation of
lipids and cytoplasmic enlargement. These changes were dependent on the exogenous
ligand and the cytoplasmic domain of the receptor. These results suggest that the
VLDL receptor functions as a regulator of cell growth and differentiation, which may be distinct from its
lipid-incorporating function.