Lipid esters stored in cytoplasmic lipid droplets (CLDs) of hepatocytes are used to synthesize very low-density lipoproteins (VLDLs), into which apolipoprotein B (ApoB) is integrated cotranslationally. In the present study, by using Huh7 cells, derived from human hepatoma and competent for VLDL secretion, we found that ApoB is highly concentrated around CLDs to make "ApoB-crescents." ApoB-cresc...

The concept that hepatic cholesterol synthesis regulates hepatocyte assembly and secretion of apoB-containing lipoproteins remains controversial. The present study was carried out in HepG2 cells to examine the regulation of apoB secretion by the HMG-CoA reductase inhibitor atorvastatin. ApoB accumulation in the media was decreased by 24% and 36% at 10 microm (P < 0.02) and 20 microm (P < 0.01) ...

Apolipoprotein B (apoB) is required for the hepatic assembly and secretion of very low density lipoprotein (VLDL). The LDL receptor (LDLR) promotes post-translational degradation of apoB and thereby reduces VLDL particle secretion. We investigated the trafficking pathways and ligand requirements for the LDLR to promote degradation of apoB. We first tested whether the LDLR drives apoB degradatio...

OBJECTIVE We examined the influence of genetic variation of the ATP-binding cassette (ABC) transporter G8 on apolipoprotein B (apoB) kinetics in overweight/obese men. METHODS AND RESULTS Very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) apoB kinetics were determined in 47 men (body mass index 32+/-3 kg/m2) using stable isotope and multicompartmental modeling to estimate pr...

OBJECTIVE Cloning of the ileal apical sodium-dependent bile acid transporter (ASBT) has identified a new pharmacological target for the modulation of plasma lipoproteins. The objective of this study was to determine whether a novel, specific, minimally absorbed ASBT inhibitor (SC-435) decreases LDL cholesterol through the alteration of plasma apoB kinetics. METHODS AND RESULTS Miniature pigs ...

The effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors on the metabolism of apolipoprotein (apo) B-containing lipoproteins appear to differ according to the predominant lipoprotein profiles present and the condition being treated. In familial hypercholesterolemia, with isolated low density lipoprotein (LDL) elevations, the LDL-apoB elimination rate is increased by u...

Previously we cloned the human macrophage apolipoprotein B-48 receptor (ApoB-48R) and documented its expression in human atherosclerotic foam cells (1). Now we have identified and characterized the murine macrophage apob-48r cDNA gene sequence and its chromasomal location. The cDNA (3,615 bp) -deduced amino acid (aa) sequence (942 aa) is 45% identical to the human macrophage APOB-48R, but not t...

Epidemiological and clinical studies have consistently demonstrated that increased concentrations of LDL cholesterol in plasma are associated with increased risk of atherosclerotic cardiovascular disease (CVD). The reference method for LDL cholesterol is -quantification, a method developed by the CDC that requires ultracentrifugation and is accordingly labor intensive, time consuming, and expen...

We have previously reported a positive correlation between the expression of BHMT (betaine-homocysteine S-methyltransferase) and ApoB (apolipoprotein B) in rat hepatoma McA (McArdle RH-7777) cells [Sowden, Collins, Smith, Garrow, Sparks and Sparks (1999) Biochem. J. 341, 639-645]. To examine whether a similar relationship occurs in vivo, hepatic BHMT expression was induced by feeding rats a Met...

The concept that hepatic cholesteryl ester (CE) mass and the rate of cholesterol esterification regulate hepatocyte assembly and secretion of apoB-containing lipoproteins remains controversial. The present study was carried out in HepG2 cells to correlate the rate of cholesterol esterification and CE mass with apoB secretion by CI-1011, an acyl CoA:cholesterol acyltransferase (ACAT) inhibitor t...