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Different transport routes for high density lipoprotein and its associated free sterol in polarized hepatic cells

Item Type:Article
Title:Different transport routes for high density lipoprotein and its associated free sterol in polarized hepatic cells
Creators Name:Wuestner, D. and Mondal, M. and Huang, A. and Maxfield, F.R.
Abstract:We analyzed the intracellular transport of HDL and its associated free sterol in polarized human hepatoma HepG2 cells. Using pulse-chase protocols, we demonstrated that HDL labeled with Alexa 488 at the apolipoprotein (Alexa 488-HDL) was internalized by a scavenger receptor class B type I (SR-BI)-dependent process at the basolateral membrane and became enriched in a subapical/apical recycled compartment. Most Alexa 488-HDL was rapidly recycled to the basolateral cell surface and released from cells. Within 30 min of chase at 37°C, ∼3% of the initial cell-associated Alexa 488-HDL accumulated in the biliary canaliculus (BC) formed at the apical pole of polarized HepG2 cells. Even less Alexa 488-HDL was transported to late endosomes or lysosomes. The fluorescent cholesterol analog dehydroergosterol (DHE) incorporated into Alexa 488-HDL was delivered to the BC within a few minutes, independent of the labeled apolipoprotein. This transport did not require metabolic energy and could be blocked by antibodies against SR-BI. The fraction of cell-associated DHE transported to the BC was comparable when cells were incubated with either Alexa 488-HDL containing DHE or with DHE bound to methyl-β-cyclodextrin. We conclude that rapid, nonvesicular transport of sterol to the BC and efficient recycling of HDL particles underlies the selective sorting of sterol from HDLs in hepatocytes.
Keywords:Bile, Dehydroergosterol, Fluorescence Microscopy, Hepatocytes
Source:Journal of Lipid Research
Publisher:American Society for Biochemistry and Molecular Biology
Page Range:427-437
Date:1 March 2004
Official Publication:https://doi.org/10.1194/jlr.M300440-JLR200
PubMed:View item in PubMed

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