Resolution and reconstitution of soluble components of rat liver microsomal vitamin D3-25-hydroxylase

Yoon, Poksyn S.; DeLuca, Hector F.

doi:10.1016/0003-9861(80)90210-6

Cited by 38 publications

(5 citation statements)

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“…Cholestasis produced in rats by 3 days of bile duct ligation reduced total hepatic cytochrome P-450 by 36% (25). Strong evidence exists that both the hepatic microsomal vitamin D 25-hydroxylase (26) and the mitochondria1 vitamin D 25-hydroxylase (27) are cytochrome P-450dependent mixed function oxidases.…”

Section: Discussionmentioning

confidence: 99%

Iepatic vitamin D 25-hydroxylase: Inhibition by bile duct ligation or bile salts

et al. 1981

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Bone disease and low serum levels of 25-hydroxyvitamin D are prevalent in cholestatic syndromes such as primary biliary cirrhosis and biliary atresia. Defective hydroxylation, along with malabsorption of vitamin D, could be a factor in 25-hydroxyvitamin D depletion. To assess hepatic hydroxylation during experimental cholestasis, we studied vitamin D 25-hydroxylase activity in liver homogenates of rats after 7, 14, and 21 days of bile duct ligation. We have also studied the effects of bile acids on this enzyme in vitro. Hepatic 25-hydroxylation was depressed after 7 days ligation in only 1 of 4 animals, but by 14 days, all animals showed a marked reduction with a mean decrease of 64% in specific activity. Total liver enzyme activity was reduced by 43% at 14 days. In the ligated animals, liver histology showed progressive bile stasis, focal necrosis, bile ductular proliferation, periductular and periportal inflammation, and fibrosis. Addition of bile acids to the in vitro assay in concentrations approximating those found in cholestasis produced marked inhibition of vitamin D 25-hydroxylase activity.

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Section: Discussionmentioning

confidence: 99%

Iepatic vitamin D 25-hydroxylase: Inhibition by bile duct ligation or bile salts

et al. 1981

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“…Subsequently, many studies involving purification and characterization ofthe enzyme(s) have been performed using the liver of different experimental animals, in particular that of the rat and rabbit (2,3). In the rat, both microsomal and mitochondrial versions of the vitamin D3 25-hydroxylase have been reported (3,4).…”

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confidence: 99%

Transfected human liver cytochrome P-450 hydroxylates vitamin D analogs at different side-chain positions.

Guo

Strugnell

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et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

153

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A full-length cDNA for the human liver mitochondrial cytochrome P-450 CYP27 was cloned from a human hepatoma HepG2 cDNA library and then subcloned into the mammalian expression vector pSG5. When CYP27 cDNA was trnsfected into COS-1 tansformed monkey kidney ceRs along with adrenodoin cDNA, transected cells revealed a 10-to 20-fold higher vitamin D3-25-hydroxylase activity than nontransfected cells. Transfected cells were capable of 25-hydroxylation of vitamin D3, la-hydroxyvitamin D3 and lahydroxydihydrotachysterol3. In each case they also showed the ability to 26(27)-hydroxylate the cholesterol-like (D3) side chain. The relative rates of 25-and 26(27)-hydroxylation of la-hydroxyvitamin D3 approximately mimicked the ratio of products observed in HepG2 cells. Vitamin D2 and lahydroxyvitamin D2, both with the ergosterol-like side chain, were 24-and 26(27)-hydroxylated by CYP27. The rate of side-chain 24-, 25-, or 26(27)-hydroxylation was greater for la-hydroxylated vitamin D analogs than for their nonhydroxylated counterparts. We conclude that CYP27 is capable of24-, 25-, and 26(27)-hydroxylation of vitamin D analogs and that the nature of products Is partially dictated by the side chain of the substrate. This work has revealed that the cytochrome P-450 CYP27 may be important in the metabolism of vitamin D analogs used as drugs.The cytochrome P45S-containing enzyme vitamin D3 25-hydroxylase has been extensively studied over the past 20 years or so since the first broken-cell systems were described (1). Subsequently, many studies involving purification and characterization ofthe enzyme(s) have been performed using the liver of different experimental animals, in particular that of the rat and rabbit (2, 3). In the rat, both microsomal and mitochondrial versions of the vitamin D3 25-hydroxylase have been reported (3, 4). The human liver counterpart was believed to exist exclusively in the mitochondrial inner membrane (5). This conclusion was subsequently challenged by the observation that the microsomal fraction from human liver might contain an inhibitor(s) of the enzyme (6).The cloning of the liver mitochondrial vitamin D3 25-hydroxylase cDNA has been reported for rat (7) and rabbit (8, 9). The cloning of the presumed human homolog of the liver mitochondrial vitamin D3 25-hydroxylase has also been reported (10, 11) and this cytochrome P-450 has been named CYP27. Though Cali and coworkers (10,12) (Kingston, ON).Cell Culture and Incubation with Vitamin D Analogs. HepG2 cells were cultured as described (14). COS-1 cells were cultured in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum and antibiotics (penicillin G, 100 pg/ml; gentamicin, 5 pg/ml; and Fungizone, 300 ng/ml).Tissue culture plates (100-or 150-mm diameter) were washed twice with phosphate-buffered saline and once with medium containing antibiotics plus 1% (wt/vol) bovine serum albumin. Serum-free medium containing 1% albumin (4 ml per 100-mm plate; 10 ml per 150-mm plate) was added to each plate, followed by vitamin D anal...

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“…The microsomal system is composed sf a flavsprotein fraction and a cytschrome P-450 fraction (Yoon and DeLuca 1980 Treated rats were injected intrapitoneally with undiluted CCL, 2.0 &/kg body weight. Control rats received no CCH4.…”

Section: Introductionmentioning

confidence: 99%

Effects of acute carbon tetrachloride poisoning on vitamin D₃ metabolism in the rat

Theodossiou¹,

Kung²,

Jones³

et al. 1988

Can. J. Physiol. Pharmacol.

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To achieve biologic potency, vitamin D must undergo two successive hydroxylations, first, in the liver and then, in the kidney. Carbon tetrachloride is known to cause extensive damage to the liver, but its effect on vitamin D metabolism has not been studied thoroughly. The effect of carbon tetrachloride on renal hydroxylation of 25-hydroxyvitamin D3 has not been studied. To evaluate the acute effect of carbon tetrachloride on vitamin D metabolism in the liver, vitamin D depleted rats received a single intraperitoneal injection of carbon tetrachloride (2.0 mL/kg body weight). After 24 h, they were given 55, 550, or 5050 pmol [3H]vitamin D3 intravenously. Twenty-four hours after injection of [3H]vitamin D3, aliquots of serum and liver were analyzed for [3H]vitamin D3 and its metabolites by high performance liquid chromatography. Sera of carbon tetrachloride treated rats had higher [3H]vitamin D3 and [3H]25-hydroxyvitamin D and lower [3H]1,25-dihydroxyvitamin D3 concentrations than did control sera. Livers of carbon tetrachloride treated rats contained more [3H]vitamin D3, [3H]25-hydroxyvitamin D3, and more fat. Liver histology showed massive centrilobular necrosis in the treated rats. Thus, our experiment in rats given an acute dose of carbon tetrachloride provided no evidence of impairment of vitamin D metabolism by the liver, but offered a suggestion that 25-hydroxyvitamin D3 metabolism by the kidney might be impaired. To determine the acute effect of carbon tetrachloride on metabolism of vitamin D3 by the kidney, we studied hydroxylation of [3H]25-hydroxyvitamin D3 in isolated perfused kidney. Kidneys from the treated rats showed a 66% reduction in [3H]1,25-dihydroxyvitamin D3 production.

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Resolution and reconstitution of soluble components of rat liver microsomal vitamin D3-25-hydroxylase

Cited by 38 publications

References 31 publications

Iepatic vitamin D 25-hydroxylase: Inhibition by bile duct ligation or bile salts

Iepatic vitamin D 25-hydroxylase: Inhibition by bile duct ligation or bile salts

Transfected human liver cytochrome P-450 hydroxylates vitamin D analogs at different side-chain positions.

Effects of acute carbon tetrachloride poisoning on vitamin D₃ metabolism in the rat

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Resolution and reconstitution of soluble components of rat liver microsomal vitamin D3-25-hydroxylase

Cited by 38 publications

References 31 publications

Iepatic vitamin D 25-hydroxylase: Inhibition by bile duct ligation or bile salts

Iepatic vitamin D 25-hydroxylase: Inhibition by bile duct ligation or bile salts

Transfected human liver cytochrome P-450 hydroxylates vitamin D analogs at different side-chain positions.

Effects of acute carbon tetrachloride poisoning on vitamin D3 metabolism in the rat

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Effects of acute carbon tetrachloride poisoning on vitamin D₃ metabolism in the rat