Glucuronidation and isomerization of all-trans- and 13-CIS-retinoic acid by liver microsomes of phenobarbital- or 3-methylcholanthrene-treated rats

doi:10.1016/0006-2952(94)90179-1

Biochemical Pharmacology

Volume 47, Issue 3, 9 February 1994, Pages 485-492

https://doi.org/10.1016/0006-2952(94)90179-1 Get rights and content

Abstract

Glucuronidation and isomerization of all-trans-am-retinoic acid (tr-RA) and 13-cis-retinoic acid (13-cis-RA) were investigated in an in vitro system using liver microsomes of differently pretreated rats. In agreement with their thermodynamic stability, more retinoic acid was isomerized from the 13-cis form to the all-trans form than vice versa. Also some 9-cis-retinoic acid (9-cis-RA) could be found. Isomerization was reduced, but in contrast to glucuronidation was still important if boiled microsomes were used. This supports the view that isomerization can proceed as a non-enzymatic process. 3-Methylcholanthrene (MC) pretreatment of the rats increased the microsomal glucuronidation of 13-cis-RA and tr-RA and the formation of 13-cis-retinoyl-β-glucuronide was enhanced up to 7-fold by MC-induced rat microsomes. The rates of glucuronidation by uninduced and phenobarbital-induced rat microsomes differed only slightly. In addition to glucuronides of the applied retinoic acid isomers (13-cis-RA and tr-RA), 9-cis-RA and its glucuronide were found. Induction of retinoid glucuronidation by pretreatment with MC indicates that this metabolic reaction is catalysed by a MC-inducible UGT isozyme. After two recently described pathways (conversions of retinol to retinal and of retinyl methyl ether to retinol) this is a third step of retinoid metabolism, induced by pretreatment with MC. With human microsomes no more than traces of glucuronides were detected; also, incubations with human microsomes resulted in a lower degree of isomerization than with rat microsomal fractions.

References (41)

AB Barua et al.
Retinoyl-β-glucuronide: an endogenous compound of human blood
Am J Clin Nutr
(1986)
MH Zile et al.
Metabolites of all-trans-retinoic acid in bile: identification of all-transand 13-cis-retinoyl glucuronides
J Biol Chem
(1982)
JA Olson et al.
Enhancement of biological activity by conjugation reactions
J Nutr
(1992)
KW Bock et al.
Effects of phenobarbital and 3-methylcholanthrene on ubstrate specificity of rat liver microsomal UDP-glucuronyltransferase
Biochim Biophys Ada
(1973)
KW Bock et al.
Paracetamol glucuronidation and human phenol UDP-glucuronosyltransferase
Biochem Pharmacol
(1993)
OH Lowry et al.
Protein measurement with the Folin phenol reagent
J Biol Chem
(1951)
C Eckhoff et al.
Identification and quantitation of all-trans- and 13-cis-retinoic acid and 13-cis-4-oxoretinoic acid in human plasma
J Lipid Res
(1990)
BN Swanson et al.
Dose-dependent kinetics of all-transretinoic acid in rats: plasma levels and excretion into bile, urine, and faeces
Biochem Pharmacol
(1981)
PA Bank et al.
Effect of tetrachlorodibenzo-p-dioxin (TCDD) on the glucuronidation of retinoic acid in the rat
Biochim Biophys Acta
(1989)
H Nau
Correlation of transplacental and maternal pharmacokinetics of retinoids during organogenesis with teratogenesis

J Creech Kraft et al.

Teratogenicity and placental transfer of all-trans-, 13-cis-, 4-oxo-all-trans-, and 4-oxo-13-cisretinoic acid after administration of a low oral dose during organogenesis in mice

Toxicol Appl Pharmacol

(1989)

GL Peck et al.

Prolonged remissions of cystic acne and conglobate acne with 13-cis-retinoic acid

N Engl J Med

(1979)

EG Thorne

Topical tretinoin research: an historical perspective

J Int Med Res

(1990)

MA Smith et al.

Retinoids in cancer therapy

J Clin Oncol

(1992)

RT Franceschi

Retinoic acid: morphogen or more mysteries?

Nutr Rev

(1992)

FW Rosa et al.

Teratogen update: vitamin A congeners

Teratology

(1986)

DM Kochhar et al.

Teratogenicity and disposition of various retinoids in vivo and in vitro

C Eckhoff et al.

Characterization of oxidized and glucuronidated metabolites of retinol in monkey plasma by thermospray liquid chromatography/mass spectrometry

Biomed Mass Spectrom

(1990)

J Creech Kraft et al.

Isotretinoin (13-cis-retinoic acid) metabolism, cis-trans isomerization, glucuronidation, and transfer to the mouse embryo: consequences for teratogenicity

Teratogen Carcinogen Mutagen

(1991)

G Tzimas et al.

Transplacental pharmacokinetics of all-trans-retinoic acid in the rat: comparison between single and multiple oral application

Teratology

(1992)

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The uridine glucuronosyltransferase (UGT) 2B7 as well as UGT1A3 have been shown to catalyze the glucuronidation of atRA, although the catalytic activity of UGT1A3 was considerably lower than that of UGT2B7 towards atRA (Samokyszyn et al., 2000). Glucuronidation of atRA has also been observed in rat liver microsomes from uninduced and induced animals, but the UGT isoforms in the rat liver contributing to atRA clearance have not been identified (Genchi, Wang, Barua, Bidlack, & Olson, 1996; Sass, Forster, Bock, & Nau, 1994). Unfortunately, no systematic studies have tested atRA glucuronidation by a panel of human UGT enzymes and as such the number of UGT enzymes that can glucuronidate atRA remains unknown.
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Metabolic conversion of vitamin A (retinol) into retinoic acid (RA) controls numerous physiological processes. 9-cis-retinoic acid (9cRA), an active metabolite of vitamin A, is a high affinity ligand for retinoid X receptor (RXR) and also activates retinoic acid receptor (RAR). Despite the identification of candidate enzymes that produce 9cRA and the importance of RXRs as established by knockout experiments, in vivo detection of 9cRA in tissue was elusive until recently when 9cRA was identified as an endogenous pancreas retinoid by validated liquid chromatography–tandem mass spectrometry (LC–MS/MS) methodology. This review will discuss the current status of the analysis, occurrence, and function of 9cRA. Understanding both the nuclear receptor-mediated and non-genomic mechanisms of 9cRA will aid in the elucidation of disease physiology and possibly lead to the development of new retinoid-based therapeutics. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.
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Excess dietary vitamin A is esterified with fatty acids and stored in the form of retinyl ester (RE) predominantly in the liver. According to the requirements of the body, liver RE stores are hydrolyzed and retinol is delivered to peripheral tissues. The controlled mobilization of retinol ensures a constant supply of the body with the vitamin. Currently, the enzymes catalyzing liver RE hydrolysis are unknown. In this study, we identified mouse esterase 22 (Es22) as potent RE hydrolase highly expressed in the liver, particularly in hepatocytes. The enzyme is located exclusively at the endoplasmic reticulum (ER), implying that it is not involved in the mobilization of RE present in cytosolic lipid droplets. Nevertheless, cell culture experiments revealed that overexpression of Es22 attenuated the formation of cellular RE stores, presumably by counteracting retinol esterification at the ER. Es22 was previously shown to form a complex with β-glucuronidase (Gus). Our studies revealed that Gus colocalizes with Es22 at the ER but does not affect its RE hydrolase activity. Interestingly, however, Gus was capable of hydrolyzing the naturally occurring vitamin A metabolite retinoyl β-glucuronide. In conclusion, our observations implicate that both Es22 and Gus play a role in liver retinoid metabolism.
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Based on its central role of metabolism all-trans-RA can be considered the most important retinoid (Figs. 1 and 2). Metabolic downstream pathways of all-trans-RA include isomerization, decarboxylation and glucuronidation processes [23–25]. Metabolites of all-trans-RA generated in vivo include 13-cis-RA [26,27], 9-cis-RA [28,29], retinoyl β-glucuronide [26], 5,6-epoxy-RA [30], 4-hydroxy-RA [31], 4-oxo-RA [26,27], and 3,4-didehydro-RA [32].
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Glucuronidation and isomerization of all-trans- and 13-CIS-retinoic acid by liver microsomes of phenobarbital- or 3-methylcholanthrene-treated rats

Abstract

Am J Clin Nutr

J Biol Chem

J Nutr

Biochim Biophys Ada

Biochem Pharmacol

J Biol Chem

J Lipid Res

Biochem Pharmacol

Biochim Biophys Acta

Toxicol Appl Pharmacol

Prolonged remissions of cystic acne and conglobate acne with 13-cis-retinoic acid

N Engl J Med

Topical tretinoin research: an historical perspective

J Int Med Res

Retinoids in cancer therapy

J Clin Oncol

Retinoic acid: morphogen or more mysteries?

Nutr Rev

Teratogen update: vitamin A congeners

Teratology

Teratogenicity and disposition of various retinoids in vivo and in vitro

Characterization of oxidized and glucuronidated metabolites of retinol in monkey plasma by thermospray liquid chromatography/mass spectrometry

Biomed Mass Spectrom

Isotretinoin (13-cis-retinoic acid) metabolism, cis-trans isomerization, glucuronidation, and transfer to the mouse embryo: consequences for teratogenicity

Teratogen Carcinogen Mutagen

Transplacental pharmacokinetics of all-trans-retinoic acid in the rat: comparison between single and multiple oral application

Teratology