THE INFLUENCE OF CHOLESTERYL ESTER CONTENT ON HEPATOCYTE TRIOLEIN EMULSION UPTAKE

When triolein emulsions are enriched with cholesteryl oleate they are more readily removed by primary rat hepatocytes and HepG2 cells via an apolipoprotein E-responsive pathway. The increment in the cholesteryl ester does not appreciably change the size of the emulsion or its aff inity for the apo E protein. The cholesteryl ester enriched-emulsion d emonstrates increased apo E-mediated HepG2-binding as well as endocyto sis. The higher the content of cholesteryl ester of the particle, the greater was both the binding and the endocytosis. The increased endocy tosis was associated with increased degradation of the apo E. Choleste ryl linoleate and palmitate produced the same effects as the oleate. L ecithin-cholesterol acyltransferase additions were also able to increa se the HepG2 uptake of the emulsion. The data indicates that the incre ment in cholesterol ester occurring during maturation of plasma triacy lglycerol-rich particles facilitates hepatic remnant assimilation by a n apo E-dependent pathway.