Ribonucleic acid synthesis in rat liver during fatty acid stimulated secretion of very low density lipoproteins.
Production of very low density lipoproteins by the liver depends on the cellular availability of fatty acids. It is stimulated by the uptake of free fatty acids from the plasma and by increased lipogenesis and is inhibited by actinomycin D, suggesting that RNA synthesis is involved in the regulation of apolipoprotein synthesis. This hypothesis has been investigated in rats in vivo and in isolated perfused livers with and without stimulation by fatty acid overload: [14C] orotate incorporation in liver polyribosomal RNA is 60 per cent greater in stimulated livers as compared to controls. This increase is primarily due to a higher incorporation in bound polysomes and in those containing at least six ribosomes and does not result from the inhibition of ribonuclease. RNase digestion of polysomal RNA (4.10(-10) M enzyme, 0 degrees C, 3 h) shows that there is twice as much radioactivity in the hydrolyzed RNA of stimulated livers as compared to controls. After partial purification of poly A-rich RNA by affinity chromatography, the mass yield and radioactivity are increased by 100 per cent in stimulated livers as compared to controls. In conclusion, de novo RNA synthesis seems to be necessary for fatty acid stimulation of VLDL production.
D000818:Animals; D005591:Chemical Fractionation / Q000379:methods; D002846:Chromatography, Affinity / Q000379:methods; D005227:Fatty Acids / Q000494:pharmacology*; D066298:In Vitro Techniques; D008079:Lipoproteins, VLDL / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008970:Molecular Weight; D009963:Orotic Acid / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D051381:Rats; D012260:Ribonucleases / Q000378:metabolism; D013268:Stimulation, Chemical
D005227:Fatty Acids; D008079:Lipoproteins, VLDL; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D009963:Orotic Acid; D012313:RNA; D012260:Ribonucleases