Apolipoprotein E and lipoprotein lipase co-ordinately enhance binding and uptake of chylomicrons by human hepatocytes.

ApoE and LpL are important in the metabolism of triglyceride rich lipoproteins, and defects in either or both may result in hyperlipidaemia. It has previously been shown that ApoE and LPL specifically enhance cellular catabolism of lipoproteins by various cell lines. The authors determine in this paper the effect of ApoE and LpL on chylomicron and LDL binding and uptake by human hepatocytes in primary culture. Separate addition of ApoE and LpL greatly enhanced binding and uptake of chylomicrons. Simultaneous addition of ApoE and LPL further increased chylomicron uptake in an additive way. For LDL a different situation was observed: neither ApoE nor LPL mediated a significant increase of lipoprotein uptake. The authors conclude that ApoE and LpL co-ordinately enhance binding and uptake of chylomicrons by primary human hepatocytes. The effect appears to be independent of LDL receptors and the co-ordinate effect of ApoE and LPL may be important for normal chylomicron catabolism.