Insulin modulation of newly synthesized apolipoproteins B‐100 and B‐48 in human fetal intestine: Gene expression and mRNA editing are not involved

Abstract

We investigated insulin's effect on intestinal lipid transport and, particularly, the biogenesis of apolipoproteins crucial to lipoprotein secretion. Adding insulin (3 mU) to the serum-free medium of cultured jejunal explants from human fetuses (17-20 weeks) reduced triglyceride and chylomicron production and inhibited apo B-48 and apo B-100 secretion. When apo B mRNA was assayed by RT-PCR and its editing by primer extension, no change was detectable following the addition of insulin. HDL lipid content, apo A-1 synthesis and RNA level were unaffected by insulin. Collectively, these results suggest that the insulin-stimulated decline in intestinal chylomicron output may involve apo B co-or post-translational modifications.

The glucagon-like peptide 1 receptor is essential for postprandial lipoprotein synthesis and secretion in hamsters and mice

“…Moreover, inhibition of DPP-4 activity is also associated with potentiation of GIP action, which might be expected to partially attenuate the hypolipidaemic effects mediated through the GLP-1R. Although increased levels of insulin may also reduce plasma triacylglycerol levels and ApoB-48 secretion from the intestine [32], administration of exogenous insulin did not affect intestinal lipid absorption (ESM Fig. 1b), ruling out insulin as a mediator of sitagliptin's or exendin-4's effects on postprandial lipaemia.…”

Modification in Oxidative Stress, Inflammation, and Lipoprotein Assembly in Response to Hepatocyte Nuclear Factor 4α Knockdown in Intestinal Epithelial Cells

“…Immunoprecipitation was performed in the presence of excess polyclonal antibodies to human apolipoproteins (Roche Applied Science) at 4°C overnight (41,42). Samples were then washed with 0.05% Igepal CA-630 (Sigma) and subsequently centrifuged, resuspended in sample buffer (1.2% SDS, 12% glycerol, 60 mM Tris, pH 7.3, 1.2% ␤-mercaptoethanol, and 0.003% bromphenol blue), and analyzed by a linear 4 -15% polyacrylamide gradient preceded by a 3% stacking gel, as described previously (41)(42)(43).…”

“…Samples were then washed with 0.05% Igepal CA-630 (Sigma) and subsequently centrifuged, resuspended in sample buffer (1.2% SDS, 12% glycerol, 60 mM Tris, pH 7.3, 1.2% ␤-mercaptoethanol, and 0.003% bromphenol blue), and analyzed by a linear 4 -15% polyacrylamide gradient preceded by a 3% stacking gel, as described previously (41)(42)(43). Radioactive molecular weight standards (Amersham Biosciences) were run with the same conditions.…”

Overproduction of intestinal lipoprotein containing apolipoprotein B-48 in Psammomys obesus: impact of dietary n-3 fatty acids

“…Quenching was corrected using computerised curves generated with external standards. An aliquot of the tissue homogenate was used for protein determinations [27][28][29][30]. For the determination of secreted lipoproteins, the medium supplemented with anti-proteases was first mixed with a plasma lipid carrier (2:0.6 vol/vol) to efficiently isolate the newly synthesised triglyceride-rich lipoproteins.…”

“…Pansorbin was then added, and the mixture was reincubated at 20°C for 60 min. The immunoprecipitates were washed extensively and analysed by a linear 4 to 20% acrylamide gradient preceded by a 3% stacking gel as described previously [30]. Apo B-48 bands on gels were sectioned and counted after overnight incubation at 20°C with 1 ml BTS-450 (Beckman Instruments) and 10 ml liquid scintillation fluid (Ready Sol NA; Beckman Instruments).…”