scholarly journals Investigation of the substrate specificity of a cloned expressed human bilirubin UDP-glucuronosyltransferase: UDP-sugar specificity and involvement in steroid and xenobiotic glucuronidation

1994 ◽  
Vol 303 (1) ◽  
pp. 233-240 ◽  
Author(s):  
S B Senafi ◽  
D J Clarke ◽  
B Burchell
Keyword(s):  
Substrate Specificity ◽  
Ex Vivo ◽  
Liver Microsomes ◽  
Chinese Hamster ◽  
Genetically Engineered ◽  
Transport Processes ◽  
Chemical Structures ◽  
Catalytic Potential ◽  
Chinese Hamster V79 Cells ◽  
Udp Glucuronosyltransferase

A cloned human bilirubin UDP-glucuronosyltransferase (UGT) stably expressed in Chinese hamster V79 cells was used to assess the substrate specificity of the enzyme. The catalytic potential (Vmax/Km(bilirubin) of the enzyme with UDP-glucuronic acid (UDPGA) was 2-fold and 10-fold greater than that for UDP-xylose and UDP-glucose respectively. The formation of bilirubin mono- and di-conjugates was found to be dependent on time, UDP-sugar concentration and bilirubin concentration. Ex vivo studies demonstrated that the genetically engineered cell line was capable of the uptake and glucuronidation of bilirubin and the release of bilirubin glucuronide, indicating its usefulness in studying transport processes. Over 100 compounds, including drugs, xenobiotics and endogenous steroids, were tested as substrates for the enzyme to determine the chemical structures accepted as substrates. A wide diversity of xenobiotic compounds such as phenols, anthraquinones and flavones (many of which are in foodstuffs) were glucuronidated by the enzyme. The enzyme also had the capacity to glucuronidate oestriols and oestradiols stereoselectively. H.p.l.c. analysis of the regioselective glucuronidation of beta-oestradiol (E2) demonstrated that it was conjugated solely at its A-ring hydroxy group by the bilirubin UGT to form E2-3-glucuronide, this was in contrast with human liver microsomes which formed 3- and 17-glucuronides of this oestrogen. Studies utilizing microsomes from a Crigler-Najjar patient and inhibition of E2 glucuronidation with bilirubin indicated that the cloned expressed bilirubin UGT was the major human UGT isoform responsible for the formation of E2-3-glucuronide, which is the predominant E2 conjugate in human urine.

scholarly journals Cloning and characterization of a novel human olfactory UDP-glucuronosyltransferase

1999 ◽  
Vol 340 (3) ◽  
pp. 837-843 ◽  
Author(s):  
Gabriele JEDLITSCHKY ◽  
Andrew J. CASSIDY ◽  
Mark SALES ◽  
Norman PRATT ◽  
Brian BURCHELL
Keyword(s):  
Functional Characterization ◽  
Chinese Hamster ◽  
Neural System ◽  
Metabolizing Enzymes ◽  
Chinese Hamster V79 Cells ◽  
Udp Glucuronosyltransferase ◽  
Olfactory Tissue

Xenobiotic metabolizing enzymes in the olfactory epithelium have been suggested to catalyse inactivation and facilitate elimination of odorants. We report here the molecular cloning and functional characterization of a human olfactory UDP-glucuronosyltransferase (UGT). The cloned protein is composed of 527 amino acids with an identity of 87% with a rat olfactory UGT and of 43-62% with other human UGT isoforms. Based on the sequence homology, it has been designated hUGT2A1. The gene was mapped to chromosome 4q13 by fluorescence in situ hybridization. The expression appeared to be specific for the olfactory tissue. The substrate specificity of this isoform was assessed using Chinese hamster V79 cells stably transfected with the isolated cDNA. The expressed enzyme showed a broad substrate spectrum including a range of phenolic compounds as well as aliphatic and monoterpenoid alcohols, among them many odorants. Furthermore, some steroids, especially androgens, some drugs and carcinogens were conjugated. The results support a role of the enzyme in olfactory perception and in protection of the neural system against airborne hazardous chemicals.

Cytochrome P450 mediated reactions studied in genetically engineered V79 Chinese hamster cells

1995 ◽  
Vol 5 (Special Issue) ◽  
pp. S91-S96 ◽  
Author(s):  
Johannes Doehmer ◽  
Dietrich Holtkamp ◽  
Volker Soballa ◽  
Gottfried Raab ◽  
Wolfgang Schmalix ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Chinese Hamster ◽  
Genetically Engineered ◽  
Chinese Hamster Cells

Adenine-related compounds modulate UDP-glucuronosyltransferase (UGT) activity in mouse liver microsomes

Xenobiotica ◽  
2021 ◽  
pp. 1-25
Author(s):  
Shoji Nakamura ◽  
Ryohei Yamashita ◽  
Yuu Miyauchi ◽  
Yoshitaka Tanaka ◽  
Yuji Ishii
Keyword(s):  
Mouse Liver ◽  
Liver Microsomes ◽  
Udp Glucuronosyltransferase ◽  
Related Compounds

Abstract 5369: Mesenchymal Stem Cells Overexpressing CXCR4 (CXCR4 + -MSCs) Attenuate Remodeling of Post-Myocardial Infarction by Releasing Anti-Fibrotic Enzymes

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Tao Wang ◽  
Yigang Wang ◽  
Dongsheng Zhang ◽  
Tiemin Zhao ◽  
Atif Ashraf ◽  
...  
Keyword(s):  
Basement Membrane ◽  
Ventricular Remodeling ◽  
Interstitial Fibrosis ◽  
Ex Vivo ◽  
Genetically Engineered ◽  
Control Group ◽  
Hypoxic Conditions ◽  
Antibody Staining ◽  
Adenoviral Transduction

We hypothesize that CXCR4 + -MSCs penetrate and proliferate in infracted heart by releasing collagen degrading enzymes. We genetically engineered male mouse MSCs using ex vivo adenoviral transduction for over-expression of CXCR4/GFP or GFP alone. MSCs (G-I) or CXCR4 + -MSCs (G-II) or CXCR4 + -MSCs treated with epigallocarechin gallate (EGCG, 50μg/ml), a MT1-matrix metalloproteinases (MMPs) inhibitor (G-III) or CXCR4 + -MSCs with AMD3100 (5 μg/mL), a CXCR4-selective antagonist (G-IV). A Trans-Matrigel Chemoinvasion Assay was used to evaluate the ability of MSCs to cross the basement membrane. MMPs were analyzed by Western blot and MMP antibody staining. Sex mismatched MSCs were infused into female mice via a tail vein injection 3 days after MI. Mice in G-III were treated with EGCG (100 mg/kg, oral gavage, daily for 2 weeks) to inhibit MMPs and G-IV was treated with AMD3100 (1 mg/kg, i.p. given continually for 6 days after MI). LV fibrosis was detected by Picrosirius red staining. Echocardiography was performed at 4 weeks after MI and hearts were harvested for histological analysis. In vitro, cell migration was significantly higher in G-II in the presence of SDF-1α as compared with other groups, ( p <0.01). EGCG or AMD3100 markedly prevented this response. MMP-9 and MT1-MMP were upregulated significantly only in G-II (p<0.01) exposed to hypoxia. Infiltration of GFP and Y chromosome positive cells in the peri- or infarct area was increased significantly in G-II. CXCR4 + -MSCs penetrated more effectively into the infarcted region and survived in the ischemic environment as compared to control group. These effects were reduced with EGCG or AMD3100. The ventricular remodeling and interstitial fibrosis were also reduced in G-II but not in other groups. G-II also had less LV dilation (diastolic dimension 4.9±0.2 vs. 6.2±0.3 mm, p<0.05), EF (62±3 vs. 44±4%, p<0.05). Infarct size (31±3.8 vs 43±4.7% of LV, p<0.05) and collagen area fraction (16±2 vs. 28±4 %, p<0.05) were significantly reduced in G-2 compared to G-I. Under hypoxic conditions MMPs were upregulated in CXCR4 + -MSCs which crossed the basement membrane by releasing enzymes leading to breakdown or reduction of scar formation thus facilitating cell homing and proliferation.

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