Isolation and Characterization of the Human UGT2B7 Gene

doi:10.1006/bbrc.2000.2795

Biochemical and Biophysical Research Communications

Volume 272, Issue 2, 7 June 2000, Pages 616-621

https://doi.org/10.1006/bbrc.2000.2795 Get rights and content

Abstract

Glucuronidation is a major pathway involved in the metabolism of drugs and numerous endogenous compounds, such as bile acids and steroid hormones. The enzymes responsible for this conjugation reaction are UDP-glucuronosyltransferases (UGT). Among the UGT2B subfamily, UGT2B7 , a UGT enzyme present in the liver and several steroid target tissues, is an important member since it conjugates a large variety of compounds including estrogens, androgens, morphine, AZT, and retinoic acid. Although this enzyme is well characterized, the gene encoding the UGT2B7 protein and its promoter region remain unknown. In this article, we report the genomic organization and the promoter region of the human UGT2B7 gene. To isolate this gene, a P-1 artificial chromosome (PAC) library was screened with a full length UGT2B7 probe and a clone of approximately 100 kb in length was isolated. In addition to the UGT2B7 gene, this PAC contains two other UGT2B genes previously characterized, namely UGT2B26P and UGT2B27P. The UGT2B7 gene is composed of six exons spanning approximately 16 kb, with introns ranging from 0.7 to 4.2 kb. The 5′-flanking region of the human UGT2B7 gene contains several potential cis-acting elements such as Oct-1, Pbx-1, and C/EBP. Only one TATA-box at nucleotide −106 was found within the first 500 nucleotides relative to the adenine base of the initiator ATG codon. Characterization of the UGT2B7 gene provides insight into the organization and regulation of this important metabolic gene.

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Neurobiology of DHEA and effects on sexuality, mood and cognition
2015, Journal of Steroid Biochemistry and Molecular Biology
Citation Excerpt :
In addition SULT2A1 mRNA expression has been shown in rat brains. DHEAS is predominately transported out of the brain across the blood–brain barrier and DHEAS found in the brain is most likely due to local synthesis [1,24,25]. The mechanisms by which DHEA(S) operate his action are not fully understood [25].
Dehydroepiandrosterone (DHEA) and its sulfate ester, DHEAS, are the most abundant steroid hormones in the humans. However, their physiological significance, their mechanisms of action and their possible roles as treatment are not fully clarified.
Biological actions of DHEA(S) in the brain involve neuroprotection, neurite growth, neurogenesis and neuronal survival, apoptosis, catecholamine synthesis and secretion, as well as anti-oxidant, anti-inflammatory and antiglucocorticoid effects. In addition, DHEA affects neurosteroidogenis and endorphin synthesis/release. We also demonstrated in a model of ovariectomized rats that DHEA therapy increases proceptive behaviors, already after 1 week of treatment, affecting central function of sexual drive. In women, the analyses of clinical outcomes are far from being conclusive and many issues should still be addressed. Although DHEA preparations have been available in the market since the 1990s, there are very few definitive reports on the biological functions of this steroid. We demonstrate that 1 year DHEA administration at the dose of 10 mg provided a significant improvement in comparison with vitamin D in sexual function and in frequency of sexual intercourse in early postmenopausal women. Among symptomatic women, the spectrum of symptoms responding to DHEA requires further investigation, to define the type of sexual symptoms (e.g. decreased sexual function or hypoactive sexual desire disorder) and the degree of mood/cognitive symptoms that could be responsive to hormonal treatment. In this regard, our findings are promising, although they need further exploration with a larger and more representative sample size.
This article is part of a Special Issue entitled: Essential role of DHEA.
Haplotype analysis of UDP-glucuronocyltransferase 2B7 gene (UGT2B7) polymorphisms in healthy Japanese subjects
2006, Clinical Biochemistry
UDP-glucuronocyltransferase 2B7 (UGT2B7) catalyzes glucuronidation of various types of endogenous compounds and drugs, but the genetic basis of interindividual variation in the metabolism of these substances has not yet been sufficiently elucidated. In addition, information about single nucleotide polymorphisms (SNPs) and haplotypes of the UGT2B7 gene that encode the enzyme in the Japanese population is still far from sufficient.
We paid special attention to and performed an investigation on −327A > G, −161T > C, −138G > A, and −125T > C in the proximal promoter region, which is regarded as being important for the transcription of the UGT2B7 gene, and also on 211G > A and 802C > T, i.e., non-synonymous SNPs of exon 1 and exon 2 that encode the substrate binding domain. Their genotypes were determined by PCR-direct sequencing.
As a result of genotyping, the minor allele frequencies in 160 Japanese individuals were found to be as follows: −327SNP A allele, 0.244; −161SNP T allele, 0.244; −138SNP A allele, 0; −125SNP C allele, 0.078; 211SNP T allele, 0.148 and 802SNP T allele, 0.244. By computational haplotype analysis, it was found that these regions formed a linkage disequilibrium block, and the presence of five haplotypes was demonstrated.
These results suggest that the haplotype structure in the Japanese population is different from that of other ethnic groups.
TALE homeodomain proteins regulate gonadotropin-releasing hormone gene expression independently and via interactions with Oct-1
2004, Journal of Biological Chemistry
Citation Excerpt :
In fact, the Pbx/Prep-binding site at –100 partially overlaps the Oct-1-binding sequence (Fig. 3B). Similar co-location has been noted in several additional promoters (39–43). Despite these observations, protein-protein interaction in the context of DNA has not yet been explored.
Gonadotropin-releasing hormone (GnRH) is the central regulator of reproductive function. Expression of the GnRH gene is confined to a rare population of neurons scattered throughout the hypothalamus. Restricted expression of the rat GnRH gene is driven by a multicomponent enhancer and an evolutionarily conserved promoter. Oct-1, a ubiquitous POU homeodomain transcription factor, was identified as an essential factor regulating GnRH transcription in the GT1-7 hypothalamic neuronal cell line. In this study, we conducted a two-hybrid interaction screen in yeast using a GT1-7 cDNA library to search for specific Oct-1 cofactors. Using this approach, we isolated Pbx1b, a TALE homeodomain transcription factor that specifically associates with Oct-1. We show that heterodimers containing Pbx/Prep1 or Pbx/Meis1 TALE homeodomain proteins bind to four functional elements within the GnRH regulatory region, each in close proximity to an Oct-1-binding site. Cotransfection experiments indicate that TALE proteins are essential for GnRH promoter activity in the GT1-7 cells. Moreover, Pbx1 and Oct-1, as well as Prep1 and Oct-1, form functional complexes that enhance GnRH gene expression. Finally, Pbx1 is expressed in GnRH neurons in embryonic as well as mature mice, suggesting that the associations between TALE homeodomain proteins and Oct-1 regulate neuron-specific expression of the GnRH gene in vivo.
Inactivation of androgens by UDP-glucuronosyltransferase enzymes in humans
2003, Trends in Endocrinology and Metabolism
In humans, 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-HSD and 5α-reductase activities in androgen target tissues, such as the prostate and skin, convert dehydroepiandrosterone, androstenedione and testosterone into the most potent natural androgen dihydrotestosterone (DHT). This androgen is converted mainly in situ into two phase I metabolites, androsterone (ADT) and androstane-3α,17β-diol (3α-DIOL), which might be back converted to DHT. Here, we discuss the recent findings regarding the characterization of specific UDP-glucuronosyltransferases (UGTs), UGT2B7, B15 and B17, responsible for the glucuronidation of these metabolites. The tissue distribution and cellular localization of the UGT2B transcripts and proteins in humans clearly indicate that these enzymes are synthesized in androgen-sensitive tissues. It is postulated that the conjugating activity of UGT enzymes is the main mechanism for modulating the action of steroids and protecting the androgen-sensitive tissues from deleteriously high concentrations of DHT, ADT and 3α-DIOL.
The cynomolgus monkey (Macaca fascicularis) is the best animal model for the study of steroid glucuronidation
2003, Journal of Steroid Biochemistry and Molecular Biology
Intense research efforts performed during the past decade clearly established the major role of glucuronidation and uridine-diphospho-glucuronosyltransferase (UGT) enzymes for steroid metabolism in humans. However, a clear understanding of the physiological importance of this metabolic process requires in vivo studies. Numerous evidences ascertain that simians are the most appropriate animal models for such studies. Indeed human and monkey have a similar pattern of steroidogenesis, unlike common laboratory mammals such as rat or mouse. Furthermore, human and monkey are unique in having high levels of circulating androsterone glucuronide and androstane-3α-diol glucuronide (3α-Diol-G). In addition, characterization of eight monkey UGT proteins demonstrated the similarity of their conjugation activity toward steroid hormones. Like human ones, monkey enzymes are expressed in steroid target tissues, where they preferentially glucuronidate androgen and estrogen metabolites. In monkey tissues, immunohistochemical studies demonstrated that UGT2B proteins are expressed in a cell-type specific manner in ovary and kidney, where they control androgens and aldosterone inactivation. These results identify the cynomolgus monkey as an appropriate animal model for the determination of cellular localization of UGT enzymes in steroid target tissues and for the identification of endogenous or exogenous stimuli affecting steroid glucuronidation.
Age- and therapy-related effects on morphine requirements and plasma concentrations of morphine and its metabolites in postoperative infants
2003, British Journal of Anaesthesia
Citation Excerpt :
Recently, it was shown that UGT2B7 is responsible for the glucuronidation of morphine and is capable of catalysing the glucuronidation of both the 3- and 6-hydroxyl moieties on these molecules.40 41 However, polymorphism in the coding sequence, as well as in the 5′-flanking region, may affect the rate of morphine glucuronidation and can result in individual differences.42 The SSS was developed as a measure of the severity of surgical stress.18
To investigate clinical variables such as gestational age, sex, weight, the therapeutic regimens used and mechanical ventilation that might affect morphine requirements and plasma concentrations of morphine and its metabolites.
In a double-blind study, neonates and infants stratified for age [group I 0–4 weeks (neonates), group II ≥4–26 weeks, group III ≥26–52 weeks, group IV ≥1–3 yr] admitted to the paediatric intensive care unit after abdominal or thoracic surgery received morphine 100 µg kg⁻¹ after surgery, and were randomly assigned to either continuous morphine 10 µg kg⁻¹ h⁻¹ or intermittent morphine boluses 30 µg kg⁻¹every 3 h. Pain was measured using the COMFORT behavioural scale and a visual analogue scale. Additional morphine was administered on guidance of the pain scores. Morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) plasma concentrations were measured before, directly after, and at 6, 12 and 24 h after surgery.
Multiple regression analysis of different variables revealed that age was the most important factor affecting morphine requirements and plasma morphine concentrations. Significantly fewer neonates required additional morphine doses compared with all other age groups (P<0.001). Method of morphine administration (intermittent vs continuous) had no significant influence on morphine requirements. Neonates had significantly higher plasma concentrations of morphine, M3G and M6G (all P<0.001), and significantly lower M6G/morphine ratio (P<0.03) than the older children. The M6G/M3G ratio was similar in all age groups.
Neonates have a narrower therapeutic window for postoperative morphine analgesia than older age groups, with no difference in the safety or effectiveness of intermittent doses compared with continuous infusions in any of these age groups. In infants >1 month of age, analgesia is achieved after morphine infusions ranging from 10.9 to 12.3 µg kg⁻¹ h⁻¹ at plasma concentrations of <15 ng ml⁻¹.
Br J Anaesth 2003; 90: 642–52

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¹: These authors contributed equally.

²: To whom correspondence should be addressed at Laboratory of Molecular Endocrinology, CHUL Research Center, 2705 Laurier Blvd., Québec, G1V 4G2, Canada. Fax: (418) 654-2761. E-mail: [email protected].

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Regular ArticleIsolation and Characterization of the Human UGT2B7 Gene

Abstract

J. Biol. Chem.

Prog. Nucleic Acid Res. Mol. Biol.

FEBS Lett.

J. Biol. Chem.

Biochem. Biophys. Res. Commun.

Biochem. Byophys. Res. Comm.

J. Biol. Chem.

Genomics

Genomics

J. Mol. Biol.

Arch. Bio. Biophy.

Glucuronidation of Drugs and Other Compounds

The UDP glycosyltransferase gene superfamily: Recommended nomenclature update based on evolutionary divergence

Pharmacogenetics

Cloning of a human liver microsomal UDP-glucuronosyltransferase cDNA

Biochem. J.

Characterization and substrate specificity of UGT2B4(E458): A UDP-glucuronosyltransferase encoded by a polymorphic gene

Pharmacogenetics

Complementary deoxyribonucleic acid cloning and expression of a human liver uridine diphosphate-glucuronosyltransferase glucuronidating carboxylic acid-containing drugs

J. Pharmacol. Exp. Ther.

Characterization of a cloned human dihydrotestosterone/androstanediol UDP-Glucuronosyltransferase and its comparison to other steroid isoforms

Biochemistry

Isolation and characterization of UGT2B15(Y85): A UDP- glucuronosyltransferase encoded by a polymorphic gene

Pharmacogenetics

Regular Article
Isolation and Characterization of the Human UGT2B7 Gene