UPTAKE OF CHYLOMICRON REMNANTS AND HEPATIC LIPASE-TREATED CHYLOMICRONS BY A NONTRANSFORMED MURINE HEPATOCYTE CELL-LINE IN CULTURE

AML 12 is a recently established differentiated, non-transformed hepat ocyte cell line derived from mice transgenic for transforming growth f actor alpha (Wu et al. (1994) Proc. Natl. Acad. Sci. 91, 674-678). The ability of these cells to take up [H-3]cholesterol-labeled in vivo-ge nerated chylomicron remnants, as well as [H-3]cholesterol-labeled chyl omicrons treated with hepatic lipase in vitro was investigated. Both t ypes of lipoprotein particles were taken up by the AML hepatocytes at a much faster rate than intact chylomicrons, and in a saturable and sp ecific manner. Chylomicrons treated with hepatic lipase in vitro compe ted with in vivo-generated chylomicron remnants for uptake by the AML hepatocytes, and the uptake of both types of lipoproteins was inhibite d by lactoferrin, suggesting that they share the same process of cellu lar recognition and uptake. It is suggested that hepatic lipase-treate d chylomicrons may be valuable in studies aimed at gaining a better un derstanding of the processes involved in the hepatic recognition and u ptake of chylomicron remnants. AML hepatocytes, which can be maintaine d as replicating, untransformed, and differentiated under standard cul ture conditions, may be useful and practical for such studies.