Intracellular apoprotein B degradation is suppressed by decreased albumin concentration in Hep G2 cells

Kidney International
T HiranoS Nagano

Abstract

It is generally accepted that hepatic secretion of apoprotein (apo) B-containing lipoproteins is substantially increased in nephrosis. To elucidate the mechanisms for the oversecretion of apo B, we investigated the effect of a various concentration of albumin on apo B kinetics in the absence or presence of oleate in Hep G2 cells. Hep G2 cells were labeled with [3H]-leucine in leucine-free medium containing 0, 1.5, 3.0 or 4.5% BSA for 180 minutes, and the secreted radiolabeled apo B, apo A1 and albumin were isolated by immunoprecipitation and counted. The secretions of apo B and albumin were suppressed by BSA (bovine serum albumin) in a dose-dependent manner, but the secretion of apo A1 was not suppressed significantly. Oleate (0.4 mM) increased the rate of apo B secretion by 2.5-fold when oleate was bound to 1.5% BSA, but at higher concentrations of BSA (3.0 or 4.5%), apo B secretion was less responsive to oleate. A pulse-chase study indicated that early apo B degradation was significantly suppressed in cells incubated with lower concentrations of BSA (0 or 1.5% BSA), thereby rapidly stimulating apo B secretion. Oleate (0.4 mM) potently inhibited apo B degradation when oleate was bound to 1.5% BSA, whereas the inhibition was no...Continue Reading

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Citations

Mar 21, 1998·Lipids·A al-ShurbajiL Berglund
Jun 1, 1996·Diabetes Research and Clinical Practice·G YoshinoT Kazumi
Jan 14, 2004·Kidney International·Florian KronenbergHans Dieplinger
Feb 27, 2008·Nihon Naika Gakkai zasshi. The Journal of the Japanese Society of Internal Medicine·Tsutomu Hirano
Oct 18, 2013·Clinical and Experimental Nephrology·Tsutomu Hirano
Dec 21, 2012·Journal of Stroke and Cerebrovascular Diseases : the Official Journal of National Stroke Association·Baidarbhi ChakrabortySarita Agarwal
Oct 27, 1997·American Journal of Kidney Diseases : the Official Journal of the National Kidney Foundation·W S YangS B Kim

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