Regulation of squalene epoxidase activity in rat liver. 1990

T Satoh, and Y Hidaka, and T Kamei
Central Research Laboratories, Banyu Pharmaceutical Co., Ltd., Tokyo, Japan.

Regulation of squalene epoxidase activity was examined in rat hepatic microsomes. The hepatic squalene epoxidase activity was high in the dark period and low in the light period. Three percent cholestyramine feeding increased the hepatic squalene epoxidase activity by 2.5-fold, and the administration of lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, increased its activity by 2.1-fold. Co-administration of cholestyramine and lovastatin had a synergistic effect increasing the activity by 7.0-fold. On the other hand, cholesterol feeding reduced hepatic squalene epoxidase activity to 18%. The addition of sodium fluoride, a phosphatase inhibitor, and the treatment of the microsomes with ATP-Mg2+ had no effect on enzyme activity. HMG-CoA reductase activity has been reported to be regulated by cholesterol and unidentified metabolite(s) derived from mevalonate. However, since squalene epoxidase is less responsive than the reductase to the treatment with lovastatin, squalene epoxidase is thought to be regulated only by cholesterol pool.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008099 Liver A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances. Livers
D008148 Lovastatin A fungal metabolite isolated from cultures of Aspergillus terreus. The compound is a potent anticholesteremic agent. It inhibits 3-hydroxy-3-methylglutaryl coenzyme A reductase (HYDROXYMETHYLGLUTARYL COA REDUCTASES), which is the rate-limiting enzyme in cholesterol biosynthesis. It also stimulates the production of low-density lipoprotein receptors in the liver. Lovastatin, 1 alpha-Isomer,Mevinolin,6-Methylcompactin,Lovastatin, (1 alpha(S*))-Isomer,MK-803,Mevacor,Monacolin K,1 alpha-Isomer Lovastatin,6 Methylcompactin,Lovastatin, 1 alpha Isomer,MK 803,MK803,alpha-Isomer Lovastatin, 1
D008862 Microsomes, Liver Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough. Liver Microsomes,Liver Microsome,Microsome, Liver
D010105 Oxygenases Oxidases that specifically introduce DIOXYGEN-derived oxygen atoms into a variety of organic molecules. Oxygenase
D011919 Rats, Inbred Strains Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding. August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
D002784 Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Epicholesterol
D002791 Cholesterol, Dietary Cholesterol present in food, especially in animal products. Dietary Cholesterol
D002792 Cholestyramine Resin A strongly basic anion exchange resin whose main constituent is polystyrene trimethylbenzylammonium Cl(-) anion. Cholestyramine,Colestyramine,Colestyramin,Cuemid,MK-135,Quantalan,Questran,Cholestyramine Resins,Cholestyramines,Colestyramines,Colestyramins,Cuemids,MK 135,MK135,Quantalans,Questrans,Resin, Cholestyramine,Resins, Cholestyramine
D004790 Enzyme Induction An increase in the rate of synthesis of an enzyme due to the presence of an inducer which acts to derepress the gene responsible for enzyme synthesis. Induction, Enzyme

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