Dissertations / Theses on the topic 'UDP-glucuronosyltransferase'

The UDP-glucuronosyltransferases (GT) represent a major family of drug-metabolising enzymes, but little is known about their multiplicity in man. The aims of this project were to purify and characterise a GT isozyme from human liver, and to investigate glucuronidation in rat and human hepatocytes, with the aim of using human hepatocytes in primary culture as an in vitro model for the study of human drug metabolism. Chromatofocusing of human liver microsomes produced separation of GT isozymes, providing evidence for heterogeneity. However, purification in an active form was not achieved, due to lability in the presence of detergent. Rat liver 17β-hydroxysteroid-GT was purified, and antibodies raised against this protein recognised a single protein in human liver microsomes. Rates of glucuronidation of 1-naphthol and phenolphthalein were significantly higher in rat hepatocyte homogenates than in hepatocytes, the magnitude of the difference being greater for 1-naphthol. This was attributed to the presence of excess UDPGA in homogenate assays and the limitation imposed by lipophilicity on substrate uptake into cells by passive diffusion. In contrast, the rate of bilirubin glucuronidation was greater in hepatocytes, possibly as a result of intact carrier-mediated uptake mechanisms, combined with a suitable environment for efficient delivery of bilirubin to the endoplasmic reticulum by membrane-membrane transfer. The same three substrates were glucuronidated at a reduced rate in human compared with rat hepatocytes, apparently due to a lower intracellular UDPGA level and isozyme-specific differences in intrinsic activity and latency. As a result, the rate of glucuronidation of all these substrates was greater in human hepatocyte homogenates than in hepatocytes. Isozyme-specific changes were observed in GT activities in human hepatocytes in primary culture, indicating the need to develop culture systems allowing stable expression of these enzymes before such a model could be used for predictive human drug metabolism.

Hepatic UDP-GTs are partly responsible for metabolism of the thyroid hormone, thyroxine (T4), in mammals, but little is known of UDP-GT activity in birds. To determine the ontogenic pattern of UDP-GT activity in precocial birds, we measured activity in Japanese quail (Coturnix japonica) liver at days 12 and 14 of the 16.5-day incubation, 3 perihatch stages and <1, 1, 4, 6, 7, 20 and 42 days posthatch. We used an enzymatic reaction with para-nitrophenol (pNP) as substrate that was validated for quail tissue. The pattern of UDP-GT development included low embryonic activity, increased activity beginning in the perihatch period, a peak in activity at day 4 posthatch and a return to lower activity levels from day 6 to adults. The profile of UDP-GT activity, in relation to the ontogeny of circulating T4 and triiodothyronine (T3) in quail, is consistent with UDP-GT playing a role in regulating circulating T4 and with the perihatch peak in T3 stimulating the posthatch peak in UDP-GT activity. To examine the effects of polychlorinated biphenyls (PCBs) on UDP-GT in developing precocial birds, we dosed chicken (Gallus domesticus) eggs with concentrations of PCB 126 from 0 to 0.80 ng/g egg (in sunflower oil) prior to incubation. Tissues were sampled at day 20 of the 21-day incubation and assayed for plasma hormones and UDP-GT activity. Eggs also were dosed with 0 or 0.25 ng PCB 126/g egg or with 0 or 0.64 ng/g egg of the coplanar PCB 77, allowed to hatch, and sampled at 42 days posthatch. There was no consistent pattern of altered thyroid hormones or UDP-GT activity in developing chickens exposed to either of these coplanar PCBs although previous studies indicated developmental alterations from exposure to the higher doses.
Master of Science

The UDP-glucuronosyltransferases (UGTs) are a superfamily of enzymes that glucuronidate small, lipophilic molecules, thereby altering their biological activity and excretion. In humans, important examples of UGT substrates include molecules of both endogenous and xenobiotic origin; thus, UGTs are considered essential contributors to homeostatic regulation and an important defence mechanism against chemical insult. In keeping with both roles, UGTs are most strongly expressed in the liver, a predominant organ involved in detoxification. Rates of glucuronidation in humans are neither uniform among individuals, nor constant in an individual over time. Genetic determinants and non-endogenous signals are both known to influence the expression of UGTs, which in turn may affect the efficacy of certain pharmaceutical treatments or alter long-term risk of developing disease. Thus, this thesis focuses on the transcriptional regulation of UGT genes in humans, particularly on mechanisms that are likely to be relevant to their expression and variation in the liver. Two major approaches were used: firstly, extensive studies of several UGT promoters were performed to identify and characterise transcriptional elements that are important for UGT expression; and secondly, important hepatic transcription factors were investigated as potential regulators of UGT genes. UGT1A3, UGT1A4 and UGT1A5 are a subset of highly related, but independently regulated, genes of the human UGT1 subfamily. UGT1A3 and UGT1A4 are expressed in the liver, whereas UGT1A5 is not. The presented analysis of the UGT1A3, UGT1A4 and UGT1A5 proximal promoters demonstrates that a hepatocyte nuclear factor (HNF)1-binding site common to all three promoters is important for UGT1A3 and UGT1A4 promoter activity in vitro, but is insufficient to drive UGT1A5 expression. Two additional elements required for the maximal activity of the UGT1A3 promoter were also identified that may distinguish this gene from UGT1A4. UGT1A3 was investigated further, focusing on mechanisms that may contribute to interindividual variation in UGT1A3 expression. Polymorphisms in the UGT1A3 proximal promoter were identified and their functional consequences tested. Known variants of HNF1alpha were also tested for altered activity towards the UGT1A3 gene. UGT1A9 is the only hepatic member of the UGT1A7-1A10 subgroup of UGT1 enzymes. Previous work had identified HNF1-binding sites in all four genes, and HNF4alpha as an UGT1A9-specific regulator. The work presented herein extends these findings to show that HNF1 factors and HNF4alpha synergistically regulate UGT1A9, and that HNF4alpha is not the only transcription factor responsible for the unique presence of UGT1A9 in the liver. Liver-enriched transcription factors screened as potential UGT regulators were chosen from the HNF1, HNF4, HNF6, FoxA and C/EBP protein families. Functional interactions newly identified by this work were HNF4alpha with UGT1A1 and UGT1A6, HNF6 with UGT1A4 and UGT2B11, FoxA1 and FoxA3 with UGT2B11, UGT2B15 and UGT2B28 and C/EBPalpha with UGT2B17. Observations were also made regarding different patterns of interaction between each UGT and the transcription factors tested, particularly HNF1alpha.

Flavonoids are polyphenolics compounds that constitute a major group of plant specialized metabolites, biosynthesized via the phenylpropanoid/polymalonate pathways. The resulting specialized metabolites can be due to decoration of flavonoid compounds with sugars, usually glucose, by the action of regiospecific UDP-glycosyltransferase (UGT) enzymes. In some cases, glycosylation can involve enzymatic attachment of other sugar moieties, such as glucuronic acid, galactose, rhamnose or arabinose. These modifications facilitate or impact the bioactivity, stability, solubility, bioavailability and taste of the resulting flavonoid metabolites. The present work shows the limitations of utilizing mammalian UDP-glucuronosyltransferases (UGATs) for flavonoid glucuronidation, and then proceeds to investigate plant UG(A)T candidates from the model legume Medicago truncatula for glucuronidating brain-targeted flavonoid metabolites that have shown potential in neurological protection. We identified and characterized several UG(A)T candidates from M. truncatula which efficiently glycosylate various flavonoids compounds with different/multiple regiospecificities. Biochemical characterization identified one enzyme, UGT84F9, that efficiently glucuronidates a range of flavonoid compounds in vitro. In addition, examination of the ugt84f9 gene knock-out mutation in M. truncatula indicates that UGT84F9 is the major UG(A)T enzyme that is necessary and sufficient for attaching glucuronic acid to flavonoid aglycones, particularly flavones, in this species. Finally, the identified UG(A)T candidates were analyzed via homology modeling and site-directed mutagenesis towards increasing the repertoire of UG(A)Ts applicable for synthesis of flavonoid glucuronides with potential human health benefits in neurological protection.

Free and microencapsulated hepatocytes in an alginate-polylysine-alginate artificial membrane (APA), were implanted intraperitoneally into the Gunn rat, the animal model for Crigler-Najjar syndrome, to reduce serum bilirubin level. Hepatocytes from guinea pigs, Wistar and Sprague-Dawley rats whether free or microencapsulated were equally effective in lowering serum bilirubin levels in the Gunn rat. Buffalo rat hepatocytes however, were immunorejected unless microencapsulated. Decrease in serum bilirubin was concomitant with the appearance of conjugated bilirubin in the bile of Gunn rats as demonstrated by HPLC analysis. Microcapsules containing guinea pig hepatocytes showed less fibrosis than microcapsules containing hepatocytes from different strains of rats and empty microcapsules. In the Gunn rat there is significant accumulation of bilirubin in various tissues which affects the net removal of bilirubin upon implantation of the encapsulated hepatocytes. This deposition increases with time and it is organ-dependent. The kinetic data of UDP-glucuronosyltransferase (UDPGT) indicated that it is a multisubunit enzyme in which there is cooperative binding of the substrate to the subunits. The binding of bilirubin showed positive cooperativity while the binding of UDPGA exhibited kinetics with mixed cooperativity. Encapsulated hepatocytes when incubated with bilirubin and UDP-glucuronic acid can form bilirubin conjugates. This was shown by HPLC analysis.The comparison of UDPGT activity between liver homogenate, intact hepatocytes and encapsulated hepatocytes showed that there is mass transfer resistance of the APA membrane.

Nous avons exprimé deux isoformes actives d'udp-glucuronosyltransferase humaines (udpgt phénol et udpgt acide hyodeoxycholique) dans e. Coli en utilisant des vecteurs d'expression performants et des séquences de traduction améliorées. Nous avons ensuite exprimé des peptides représentant des domaines spécifiques de chaque isoforme en fusion avec la protéine a dans e. Coli. Nous avons purifié une de ces protéines par immunoaffinité et nous avons développé des anticorps spécifiques dirigés contre celle-ci

Les UDP-glucuronosyltransférases (UGTs) représentent une famille multigénique d'enzymes responsables de la biotransfoIination de substances exogènes (médicaments) et endogènes comme la bilirubine. Ces enzymes sont principalement hépatiques mais leur présence est également détectée au niveau d'autres organes comme, le cerveau, la peau, la muqueuse nasale ou le tractus gastro-intestinal. Dans le cadre d'une étude structure fonction de ces enzymes chez l'homme et le rat, afin de mieux comprendre les évènements moléculaires de la glucuronoconjugaison, nous avons utilisé une série de molécules, les catéchols, pour explorer le site actif des UGTs. Ces composés de structures différentes contiennent cependant un motif commun, le l,2-dihydroxybenzene. Les catéchols présentent des propriétés pharmacologiques et toxicologiques diverses et sont pour certains impliqués dans des processus physiologiques majeurs. La première partie de notre travail a consisté à mettre au point et développer des modèles prédictifs de prise en charge de ces substances par les UGTs hépatiques chez l'homme et le rat. Ces modèles visent à évaluer précocement le métabolisme, la toxicité et les possibles interférences médicamenteuses de nouvelles molécules catéchols à visée thérapeutique. Nous avons déterminé les paramètres stériques et électroniques caractérisant ces catéchols importants pour la catalyse, et identifié les UGT impliquées (UGT1A6, 2B1,1A9 en particulier). Dans une deuxième partie, nous avons mis en évidence une glucuronoconjugaison des catéchols au niveau du tractus gastro-intestinal. Pour certains composés la prise en charge par les UGTs est plus importante qu'aù niveau du foie, ce qui suggère une contribution importante de cet organe dans le métabolisme de ces substances. Enfin, dans une troisième partie, nous nous sommes plus particulièrement intéressés à la mécanistique de la glucuronoconjugaison des catéchols et des phénols par l'isoforme humaine UGT1A6 en identifiant les acides aminés cruciaux pour la catalyse. Par une stratégie de mutagenèse dirigée associée à l'utilisation d'agents de modification chimique, nous avons analysé le rôle de plusieurs résidus histidine. Après génération et expression des isoformes d'UGTlA6 sauvage et mutées dans la levure Pichia pastoris, l'histidine en position 370 a été identifié comme un des résidus catalytiques. D'autres résidus histidine jouent des rôles importants dans la structure ou l'interaction avec le co-substrat, l'acide UDP-glucuronique. Sur la base de ces résultats, dès mécanismes réactionnels pour la glucuronoconjugaison des phénols et des catéchols ont été proposés. En conclusion, les résultats de notre travail contribuent à mieux comprendre les phénomènes qui régissent la glucuronoconjugaison des catéchols chez l'homme et le rat.

Thesis (MSc (Plant Biotechnology))--University of Stellenbosch, 2007.
The photosynthetic protist Euglena gracilis synthesizes a storage carbohydrate named paramylon, a glucan consisting only of β-(1-3)-glycosidic linkages. The enzyme that produces paramylon is a glycosyltransferase commonly known as paramylon synthase (EC 2.4.1.34; UDP-glucose: 1,3-β-D-glucan 3-β-D-glucosyl transferase). This enzyme uses UDP-glucose as its main substrate. In 2001, Bäumer et al. isolated and partially purified paramylon synthase, but never presented any sequence information. Hence, the main aim of this project was to isolate and characterize the gene(s) coding for the paramylon synthase. Different approaches were taken in order to isolate and characterize the gene(s). In the first part of the study molecular techniques were used to try and identify the gene. The two methods used were library screening and PCR amplification. Different libraries were screened using either functional staining or an affinity probe. The second method concentrated on the use of degenerate oligonucleotides, based on the amino acid sequences of conserved regions from known β-(1-3)-glucan synthase genes from various organisms, to PCR amplify the gene sequence from Euglena. These approaches were not successful in the isolation of the gene(s). In the second part of the study protein purification techniques were used in an attempt to obtain de novo protein sequence from the purified paramylon synthase enzyme. Several protein purification techniques were tried with the most successful being preparative ultra centrifugation followed either by sucrose density centrifugation or product entrapment (a type of affinity purification). These resulted in partial purification of the paramylon synthase protein. The partially purified proteins were separated using polyacrylamide gel electrophoresis, and the polypeptides able to bind the precursor, UDP-glucose, were identified using a radiolabeled isotope of UDP-glucose. These polypeptides were subjected to LC-MS-MS in order to obtain sequence information from them. One tryptic fragment showed high homology to β-(1,3)-glucan synthase genes from different yeasts.

Des molécules originales, inhibiteurs des UDP-glucuronosyltransférases, ont été conçues, synthétisées puis testées. Ces composés constituent des sondes précieuses pour explorer l'organisation des sites actifs de ce groupe de protéines impliquées dans le métabolisme des xénobiotiques, dont les médicaments, et dans celui de substances endogènes (bilirubine, acides rétinoïques,. . . ). Les molécules synthétisées, dont la structure est analogue à celle du substrat, l'acide UDPglucuronique, permettent de caractériser plus spécifiquement le domaine peptidique interagissant avec ce co-facteur. Les principaux résultats obtenus à l'issue de ce travail sont regroupés en trois parties principales correspondant aux trois groupes d'inhibiteurs considérés. 1- Une série chimique composée d'une cinquantaine de molécules dérivées de l'uridine a été synthétisée en faisant varier la nature des motifs chimiques positionnés successivement sur le cycle pyrimidique de l'uracile ou sur les groupements 2', 3' et 5' du ribose. L'effet inhibiteur de chaque molécule a d'abord été estimé d'après la mesure des 150. Pour les inhibiteurs les plus performants, une analyse cinétique détaillée a été entreprise visant à déterminer la constante d'inhibition ainsi que le mode d'inhibition. 2- Ces inhibiteurs ont été comparés à ceux précédemment obtenus au laboratoire comme les acides arylalkyl carboxyliques (inhibiteurs compétitifs) et les N-acyl-phénylamino alcools reliés par un bras espaceur à l'uridine (analogues de l'état de transition). En particulier, ils ont été utilisés pour caractériser le site de fixation de la 4-méthylombelliférone de l'UDP-glucuronosyltransférase 1. 6 après mutation des acides aminés Histidine 54 et Arginine 52 (Mutants H54A, H54Q, R52A). 3- Une série d'inhibiteurs dérivés des acides triphénylalkyl carboxyliques comportant une fonction alcool terminale primaire à la place de l'acide carboxylique et différant par la longueur de la chaîne alkyle a été testée sur des microsomes hépatiques de rats. Ils exercent un effet inhibiteur puissant et compétitif vis-à-vis de la glucuronoconjugaison de la bilirubine. Les résultats obtenus permettent de mieux comprendre les bases moléculaires stériques et électroniques de l'interaction des substrats avec les UDP-glucuronosyltransférases
New UDP-glucuronosyltransferases inhibitors have been designed, synthetized and tested in order to probe the active sites of these proteins which are involved in the metabolism of xenobiotics, such as drugs, and endobiotics such as bilirubin, retinois acids,. . . The synthetized molecules, whose stucture is analogous to the donor substrate UDP-glucuronic acid, allowed us to characterize more specifically the peptidic domain interacting with this substrate. The maiIÏ results are gathered in three different parts, according to the group of inhibitors considered. 1- Uridine being the mother compound, a chemical series of about fifty molecules has been synthetized by varying the nature of the chemical groups placed successively on the base moiety or on the 2', 3' and 5' positions of the sugar. The inhibitory effect has frrst been estimated in terms of IC50. For the most powerful inhibitors, a detailed kinetic study gave us the inhibition constant and the type of inhibition. 2- These inhibitors have been compared to those previously obtained in the laboratory, such as arylalkyl carboxylic acids (competitive inhibitors) and N-acyl-phenylamino alcohols attached to a uridine molecule by a spacer (transition-state analogs). They have been used to characterize binding site of 4-methylumbelliferone of the UDP-glucuronosyl transferase 1. 6 after mutation of amino-acids His54 and Arg52 (mutants H54A, H54Q and R52A). 3- A series of inhibitors derived from triphenylalkyl carboxylic acids containing a primary alcohol group instead of the carboxylic acid group and with various carbon chain length has been tested on rats hepatic microsomes. They show a strong inhibitory effect on bilirubin glucuronidation. The results obtained allowed us to better understand the molecular and electronic basis of substrates interaction with UDP-glucuronosyl transferases

Lau San Shing.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (leaves 113-120).
Abstracts in English and Chinese.
Title Page --- p.1
List of Thesis Committee --- p.2
Declaration Page --- p.3
Acknowledgements --- p.4
Table of Contents --- p.5
Abstract --- p.10
論文撰要 --- p.12
Chapter Chapter 1 --- Introduction
Chapter 1.1 --- Drug Metabolism --- p.14
Chapter 1.2 --- Glucuronidation --- p.16
Chapter 1.3 --- UDP-glucuronosyltransferase (UGTs)
Chapter 1.3.1 --- Nomenclature --- p.18
Chapter 1.3.2 --- Tissue Distributions of UGTs --- p.20
Chapter 1.3.3 --- Genetics --- p.26
Chapter 1.3.4 --- Evolution of UGTs --- p.28
Chapter 1.4 --- UDP-glucuronosyltransferase related Human Diseases --- p.33
Chapter 1.4.1 --- Hyperbilirubinemia --- p.33
Chapter 1.4.2 --- Cancer --- p.37
Chapter 1.5 --- Rattus norvrgicus UDP-glucuronosyltransferase 1A8 --- p.38
Chapter 1.6 --- Aims of the Project --- p.42
Chapter Chapter 2 --- Materials and Methods
Chapter 2.1 --- Materials
Chapter 1. --- Rat liver mRNA Extraction --- p.43
Chapter 2. --- RT-PCR of rat liver mRNA --- p.43
Chapter 3. --- Amplification of UGT1A8 gene from the cDNA library --- p.43
Chapter 4. --- Construction of bacterial expression vector --- p.43
Chapter 5. --- Expression of recombinant protein in E.coli --- p.44
Chapter 6. --- Purification of protein with Ni column --- p.44
Chapter 7. --- Purification of protein with gel filtration column --- p.44
Chapter 8. --- Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) --- p.44
Chapter 9. --- Concentration and Desalting of protein --- p.45
Chapter 10. --- Enzyme activity of glucuronidation --- p.45
Chapter 11. --- Near UV and far UV circular dichroism (CD) spectroscopy --- p.45
Chapter 12. --- Fluorescent properties studies --- p.45
Chapter 13. --- Western Blotting --- p.46
Chapter 14. --- 3D modeling of UGT1A8 and interactions with ligands --- p.46
Chapter 2.2 --- Methods
Chapter 1. --- Rat liver mRNA extraction --- p.46
Chapter 2. --- RT-PCR of rat liver mRNA --- p.47
Chapter 3. --- Amplification of UGT1A8 gene from the cDNA library --- p.48
Chapter 4. --- Cloning of UGT1A8 PCR product into expression vector pRSet B --- p.49
Chapter 5. --- Confirmation of the presence of insert in the plasmid --- p.51
Chapter 6. --- Sequence checking for UGT1A8 gene in the pRSet B vector --- p.52
Chapter 7. --- Expression of recombinant protein in E.coli JM109(DE3) cell strain --- p.52
Chapter 8. --- Purification of recombinant protein by Ni-column --- p.53
Chapter 9. --- Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) --- p.53
Chapter 10. --- Recombinant protein purification by gel filtration column --- p.54
Chapter 11. --- Concentration or Desalting of Purified Protein --- p.54
Chapter 12. --- Determination of Protein Concentration --- p.55
Chapter 13. --- Far- UV Circular dichroism spectroscopy --- p.55
Chapter 14. --- Intrinsic Fluorescence Studies of Proteins --- p.57
Chapter 15. --- Chemical denaturation stability studies --- p.58
Chapter 16. --- Glucuronidation protein activity assay --- p.59
Chapter 17. --- Mutagenesis --- p.60
Chapter 18. --- Western Blotting for the presence of protein --- p.61
Chapter 19. --- Protein Modeling with Insight II
Chapter 19.1 --- Construction of substrate 1-napthol structure --- p.62
Chapter 19.2 --- Obtaining UDP-glucuronic acid in PDB file --- p.63
Chapter 19.3 --- Obtaining rat UGT1A8 model structure in PDB file --- p.63
Chapter 19.4 --- Optimization of rat UGT1A8 structure --- p.63
Chapter 19.5 --- Docking studies of interaction between ligands and protein
Chapter 19.5.1 --- Setting up a Grid --- p.66
Chapter 19.5.2 --- Docking of 1-napthol to UGT1A8 --- p.67
Chapter 19.5.3 --- Docking of UDP-glucuronic acid in the complex of UGT1A8 and1- napthol --- p.68
Chapter 19.5.4 --- Definition of Subsets --- p.68
Chapter Chapter 3 --- Results --- p.70
Figure 3.1 The extracted RNA from rat liver tissue --- p.76
Figure 3.2 DNA gel of PCR amplified gene product --- p.77
Figure 3.3 Colony PCR of UGT1 A8-pRSetB transformed DH5 a bacteria --- p.78
Figure 3.4 The alignment of amplified gene sequence with the rat UGT1A8 sequence on NCBI database --- p.79
Figure 3.5 SDS-PAGE of cell lysates with different expression temperature and time duration --- p.82
Figure 3.6 SDS-PAGE of bacterial cell lysates --- p.83
Figure 3.7 SDS-PAGE of Ni-column eluted protein --- p.84
Figure 3.8 Elution Profile of Gel Filtration Chromatography --- p.85
Figure 3.9 SDS-PAGE analysis of UGT1A8 fractions from Ni-column and gel filtration column --- p.86
Figure 3.10 Sequence Alignment of UGTs in the rat UGT1A family and 2D structure prediction of UGT1A8 --- p.88
Figure 3.11 Circular Dichroism (CD) measurements on rat UGT1A8 --- p.89
Figure 3.12 Western Blotting of UGT1A8 wild-type and mutant proteins --- p.91
Table 3.1 The specific activity of wild-type and mutated proteins --- p.92
Figure 3.13 Fluorescence spectrum of wild type and two charged-residue mutants ofUGTlA --- p.93
Figure 3.14 Fluorescence spectrum of wild type and Trp mutants of UGT1A8 --- p.94
Figure 3.15 Chemical denaturation of wild type and Trp-mutated UGT1A8 proteins --- p.95
Figure 3.16 Resolved Stern-Volmer plot of UGT1A8 on acrylamide quenching --- p.96
Figure 3.17 The 3D modeling structure of rat UGT1A8 --- p.97
Figure 3.18 Modeling simulated the interaction between UDP-glucuronic acid and UGT1A8 --- p.98
"Figure 3.19 Modeling simulated the interaction between UDP-glucuronic acid, 1-napthol and UGT1A8" --- p.99
Chapter Chapter 4 --- Discussion
Chapter 1. --- Successful Expression of Rat UGT1A8 --- p.100
Chapter 2. --- The recombinant rat UGT1A8 protein was properly folded and enzymatic functioning --- p.102
Chapter 3. --- Purified recombinant rat UGT1A8 protein contained well-ordered structure --- p.103
Chapter 4. --- "Relative positions of Trp38, Trp64, Trp98 and Trp208 in the protein" --- p.105
Chapter 5. --- Contribution of Trp residues in the folding and stability of the protein --- p.106
Chapter 6. --- Probing of substrate coupling region by mutagenesis --- p.108
Chapter 7. --- Interaction studies of substrates and UDP-glucuronic acid with UGT1A8 by computer modeling and docking simulation --- p.109
Chapter Chapter 5 --- Conclusion --- p.111
Chapter Chapter 6 --- References --- p.113

碩士
臺北醫學大學
藥學研究所
97
Lung cancer is the leading cause of cancer deaths in Taiwan. The carcinogenesis process involves activated carcinogens which lead to mutations of crucial oncogenes resulting in tumor development. UGT1A7 (UDP-glucuronosyltransferases1A7) is an important extrahepatic enzyme that detoxifies a variety of lung carcinogens. Genetic polymorphisms in UGT1A7 were shown to have decreased catalytic activity when compared to the wild-type protein and therefore implicated as a cancer risk factor. The purpose of this study was to investigate the association between genetic polymorphisms of UGT1A7 gene and lung cancer in the Taiwanese population. In addition, since KRAS mutation is highly associated with tobacco smoking, we further hypothesized that UGT1A7 polymorphisms might be correlated with the risk of developing this mutation. The 210 lung cancer patients and 210 healthy individuals enrolled in this matched case-control study were genotyped for UGT1A7 polymorphisms using PCR-RFLP method. Tumor tissues available from 150 patients were also tested for KRAS codon 12 and 13 mutations. Predicted intermediate-activity UGT1A7 genotypes (UGT1A7*1/*2, UGT1A7*1/*3, UGT1A7*1/*4, UGT1A7*2/*2, UGT1A7*2/*3) and low-activity UGT1A7 genotypes (UGT1A7*3/*3, UGT1A7*4/*4) were both significantly correlated with lung cancer risk (p=0.006, odds ratio (OR): 1.799, 95% confidence interval (CI): 1.178-2.748 and p=0.032, OR: 3.333, 95% CI: 1.192-9.322, respectively). Interestingly, the risks were significant in males but not in females. Besides, those lower-activity UGT1A7 genotypes were significantly associated with lung cancer with wild-type EGFR but not with those with EGFR mutations. Of the 150 patients screened for KRAS mutations, 26 (17.3%) patients were identified. However, no association was found between UGT1A7 polymorphisms and the incidence of KRAS mutation. These results suggest that there is a potential role of UGT1A7 polymorphisms as a potential risk factor for lung cancer. Further studies are warranted to find out specific clinical characteristics and tumor biomarkers on these susceptible indivisuals. Moreover, it is also important to discover other risk factors that predispose patients to form lung cancer-related oncogenic mutations.

Leung Hau Yi.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (leaves 116-131).
Abstracts in English and Chinese.
Thesis Committee --- p.in
Acknowledgement --- p.II
Abstract --- p.III
摘要 --- p.V
Table of Contents --- p.VII
List of Figures --- p.X
List of Tables --- p.XIII
Appendix Abbreviations --- p.XIV
Chapter Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Breast Cancer --- p.1
Chapter 1.2 --- Development of Breast Cancer --- p.2
Chapter 1.3 --- Risk Factors of Breast Cancer --- p.3
Chapter 1.3.1 --- Age --- p.3
Chapter 1.3.2 --- Genetic Factors --- p.4
Chapter 1.3.3 --- Hormonal Factors --- p.5
Chapter 1.3.4 --- Lifestyles --- p.6
Chapter 1.4 --- Drug Metabolism --- p.6
Chapter 1.5 --- UGT1A1 --- p.7
Chapter 1.5.1 --- UDP-glucuronosyltransferase --- p.7
Chapter 1.5.2 --- UGT1A1 --- p.9
Chapter 1.6 --- Cytochrome P450 I Enzyme Family --- p.10
Chapter 1.6.1 --- CYP450 subfamily --- p.10
Chapter 1.6.2 --- CYP1A1 --- p.11
Chapter 1.6.3 --- CYP1B1 --- p.12
Chapter 1.7 --- Reasons why UGT1A1 is being studied --- p.13
Chapter 1.8 --- Outline of this Study --- p.14
Chapter 1.8.1 --- Effects of Over-expressing UDP-Glucuronpsyltransferase and Cytochrome P450 1A1 Against Xenobiotic Assault in Breast Cancer Cells --- p.14
Chapter 1.8.2 --- Effects of Genistein and Resveratrol on Phase I and II Enzymes in a Non-cancerous Breast Cell Line --- p.15
Chapter 1.8.3 --- Effects of UGT1A1 on Cancer Drug Treatment --- p.15
Chapter Chapter 2 --- Materials and Methods --- p.16
Chapter 2.1 --- Chemicals --- p.16
Chapter 2.2 --- Cell Culture --- p.16
Chapter 2.2.1 --- Maintenance --- p.16
Chapter 2.2.2 --- Preparation of Cell Stock --- p.17
Chapter 2.2.3 --- Cell Recovery from Liquid Nitrogen Stock --- p.17
Chapter 2.3 --- Cloning and Transfection --- p.18
Chapter 2.3.1 --- Isolation of RNA from cells and cDNA synthesis --- p.18
Chapter 2.3.2 --- Amplification of UGTlAl --- p.20
Chapter 2.3.3 --- Separation and Purification of DNA from Agarose Gel --- p.21
Chapter 2.3.4 --- Restriction Digestion --- p.22
Chapter 2.3.5 --- Ligation of DNA Fragment and Vector --- p.22
Chapter 2.3.6 --- Transformation of DH5a --- p.23
Chapter 2.3.7 --- Small Scale Plasmid Purification (Miniprep) --- p.24
Chapter 2.3.8 --- Large Scale Plasmid Purification (Maxiprep) --- p.25
Chapter 2.3.9 --- Stable Transfection into MCF-7 cells with LipofectAMINE PLUS reagent --- p.26
Chapter 2.4 --- Analytical Procedures --- p.27
Chapter 2.4.1 --- Western Blot Analysis --- p.27
Chapter 2.4.2 --- Measurement of cell proliferation (MTT assay) --- p.28
Chapter 2.4.3 --- Measurement of DMBA-DNA Adduct Formation --- p.28
Chapter 2.4.4 --- Comet Assay --- p.29
Chapter 2.4.5 --- Relative Quantitative Real Time PCR --- p.30
Chapter 2.4.5.1 --- Real Time PCR Using TaqMan Probe --- p.30
Chapter 2.4.5.2 --- Statistical Analysis of 2-ΔΔCT Comparative Gene Expression --- p.31
Chapter 2.4.6 --- Flow Cytometry --- p.31
Chapter 2.4.7 --- EROD Activity in Intact Cells --- p.31
Chapter 2.4.8 --- High Performance Liquid Chromatography --- p.32
Chapter 2.5 --- Statistical Analysis --- p.34
Chapter Chapter 3 --- Effects of Over-Expressing UDP-GIucuronosyltransferase and Cytochrome P450 1A1 Against Xenobiotic Assault in Breast Cancer Cells --- p.35
Chapter 3.1 --- Introduction --- p.35
Chapter 3.2 --- Results --- p.38
Chapter 3.2.1 --- Effectiveness of Transfection --- p.38
Chapter 3.2.2 --- Cell Proliferation Experiments --- p.41
Chapter 3.2.3 --- Regulation of Estrogen Receptor (ER) Expression --- p.43
Chapter 3.2.4 --- Formation of DMBA-DNA adduct formation --- p.45
Chapter 3.2.5 --- Single Cell Gel Electrophoresis (Comet Assay) of DMBA-induced DNA Damage in MCF-7UGT1A1 cells --- p.46
Chapter 3.2.6 --- HPLC for Estradiol-glucuronidation Analysis --- p.49
Chapter 3.2.7 --- Single Cell Gel Electrophoresis (Comet Assay) of DMBA or E2-induced DNA Damage in MCF-7cyp1A1 cells --- p.51
Chapter 3.3 --- Discussion --- p.56
Chapter Chapter 4 --- Effects of Genistein and Resveratrol on Phase I and II Enzymes in a Non-Cancerous Breast Cell Line --- p.61
Chapter 4.1 --- Introduction --- p.61
Chapter 4.2 --- Results --- p.66
Chapter 4.2.1 --- "Genistein and Resveratrol Reduced DMBA-induced UGT1A1, CYP1A1 and CYP1B1 Expression" --- p.66
Chapter 4.2.2 --- Genistein and Resveratrol Reduced the Formation of DMBA-DNA Adduct in MCF-10A Cells --- p.73
Chapter 4.2.3 --- Genistein and Resveratrol Reduced the Single Strand DNA Damage Generated by DMBA in MCF-10A Cells --- p.76
Chapter 4.2.4 --- Genistein and Resveratrol Reduced DMBA-induced EROD Activities --- p.81
Chapter 4.3 --- Discussion --- p.84
Chapter Chapter 5 --- Effects of Ugtlal on Cancer Drug Treatment --- p.89
Chapter 5.1 --- Introduction --- p.89
Chapter 5.2 --- Results --- p.93
Chapter 5.2.1 --- Cell Proliferation Experiment --- p.93
Chapter 5.2.2 --- "Expression of Bcl-2 and Bax proteins in Paclitaxel- or VCR-treated MCF-7, MCF-7control and MCF-7UGt1A1 cells" --- p.98
Chapter 5.2.3 --- Flow Cytometric Analysis of Cell Cycle Phase Distributionin Paclitaxel- or VCR-treated MCF-7 cells --- p.103
Chapter 5.3 --- Discussion --- p.110
Chapter Chapter 6 --- Summary --- p.114
Bibliography --- p.116

Wang Huan.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.
Includes bibliographical references (leaves 148-158).
Abstracts in English and Chinese.
TABLE OF CONTENTS --- p.I
LIST OF FIGURES AND TABLES --- p.VIII
ABSTRACT --- p.1
摘要 --- p.3
Chapter CHAPTER 1 --- GENERAL INTRODUCTION
Chapter I. --- The essential factors related to cancer --- p.5
Chapter a. --- Carcinogens --- p.5
Chapter b. --- Carcinogenesis pathways --- p.7
Chapter c. --- DNA adducts formation and breast cancer --- p.7
Chapter II. --- Cytochrome P450 I enzyme family --- p.8
Chapter a. --- CYP450 superfamily --- p.8
Chapter b. --- CYP1A1 --- p.10
Chapter c. --- CYP1B1 --- p.11
Chapter III. --- Transactivation of CYP1 enzymes by aryl hydrocarbon receptor (AhR) --- p.12
Chapter IV. --- Phase II enzyme UGT and cancer prevention --- p.13
Chapter V. --- Estrogen metabolism and the hormone-dependent breast cancer --- p.15
Chapter a. --- Estrogen and breast cancer initiation --- p.15
Chapter b. --- Estrogen Receptor (ER) --- p.15
Chapter c. --- Estradiol hydroxylation pathways --- p.15
Chapter VI. --- Phytochemicals and cancer prevention --- p.18
Chapter VII. --- Outline of this study --- p.20
Chapter CHAPTER 2 --- MATERIALS AND METHODS
Chapter I. --- Chemicals --- p.21
Chapter II. --- Cell culture and treatments --- p.21
Chapter 1. --- Maintenance of cells --- p.21
Chapter 2. --- Preparation of cell stock --- p.22
Chapter 3. --- Cell recovery from liquid nitrogen stock --- p.22
Chapter 4. --- Measurement of cell viability --- p.22
Chapter 5. --- Preparation of cell lysates --- p.23
Chapter 6. --- XRE-luciferase gene reporter assay --- p.23
Chapter a. --- Transient transfection of cell using lipofectamine PLUS reagent --- p.23
Chapter b. --- Dual Luciferase Assay --- p.24
Chapter III. --- Enzyme Activities --- p.24
Chapter 1. --- Isolation of microsomes --- p.24
Chapter 2. --- EROD activities in intact cells --- p.24
Chapter 3. --- EROD inhibition assay --- p.25
Chapter IV. --- Manipulation of Nuclear Acid --- p.26
Chapter 1. --- Preparation of transfected DNA --- p.26
Chapter a. --- Separation and purification of DNA from agarose gel --- p.26
Chapter b. --- Restriction digestion --- p.26
Chapter c. --- Ligation of DNA fragments --- p.27
Chapter d. --- Transformation of DH5a --- p.27
Chapter e. --- Small scale plasmid purification from DH5a (mini prep) --- p.28
Chapter f. --- Large scale plasmid isolation from DH5a (maxi-prep) --- p.28
Chapter g. --- Construction of XRE activated luciferase reporter gene --- p.29
Chapter 2. --- Measurement of DMBA-DNA adduct formation --- p.29
Chapter 3. --- Semi-quantitative RT-PCR Assay --- p.30
Chapter a. --- Isolation of RNA using TRIzol® Reagent --- p.30
Chapter b. --- RT-PCR --- p.31
Chapter V. --- Phase II enzyme-UGT activity assay --- p.32
Chapter VI. --- HPLC for estradiol-hydroxylation analysis --- p.33
Chapter 1. --- HPLC condition for hydroxyestradiol separation and measurement --- p.33
Chapter 2. --- Determination of microsomal estradiol hydroxylase activity --- p.34
Chapter 3. --- Assay of estradiol metabolism in MCF-7 cells --- p.34
Chapter VII. --- Statistical Analysis --- p.35
Chapter CHAPTER 3 --- CHALCONES ANTAGONIZE DMBA-INDUCED CARCINOGENESIS BY MODULATION OF CYP1A1/1B1 AND UGT ACTIVITIES
Chapter Part One --- Introduction --- p.36
Chapter Part Two --- Results --- p.40
Chapter Section One --- Chalcones antagonize DMBA carcinogenesis by inhibiting CYP1A1 and CYP1B1 activities --- p.40
Chapter I. --- Chalcones inhibited DMBA-induced EROD activities in MCF-7 cells --- p.40
Chapter II. --- Inhibition of chalcones on microsomal CYP1A1 & 1B1 enzyme activities --- p.43
Chapter III. --- Reduction of DMBA-induced DNA adduct by chalcones --- p.52
Chapter IV. --- Chalcones antagonized CYP1A1 XRE transactivation --- p.54
Chapter V. --- Chalcones suppressed DMBA-induced CYP1 gene expression --- p.56
Chapter Section Two --- Chalcones modulate DMBA carcinogenesis by regulating UGT activities --- p.63
Chapter I . --- Chalcones regulated UGT1A1 gene expression in MCF-7 cells --- p.63
Chapter II. --- Chalcones affected UGT enzyme activity in HepG2 cells --- p.70
Chapter III. --- Chalcones regulated UGT1A1 gene expression in HepG2 cells --- p.73
Chapter Part Three --- Discussion --- p.80
Chapter I . --- Chalcones are potential chemopreventive agents --- p.80
Chapter II. --- Chalcones modulated Phase I enzyme activities --- p.80
Chapter III. --- Chalcones regulated Phase II enzyme activities --- p.82
Chapter IV. --- Chalcones suppressed DMBA-induced DNA-adduct formation in MCF-7 cells --- p.82
Chapter V. --- The anti-carcinogenic properties of chalcones and their structures --- p.83
Chapter CHAPTER 4 --- EFFECTS OF PERILLYL ALCOHOL AND LIMONENE ON CYP1 AND UGT ENZYMES
Chapter Part One --- Introduction --- p.85
Chapter Part Two --- Results --- p.87
Chapter I. --- Perillyl alcohol and limonene modulated DMBA-induced CYP1A1/1B1 activities in MCF-7 cells --- p.87
Chapter II. --- Perillyl alcohol and limonene regulated microsomal CYP1A1/1B1 activities --- p.89
Chapter III. --- Perillyl alcohol and limonene regulated DMBA-induced DNA adduct formation in MCF-7 cells --- p.93
Chapter IV. --- Perillyl alcohol and limonene regulated CYP1A1 & CYP1B1 gene expressions in MCF-7 cells --- p.95
Chapter V. --- Effect of perillyl alcohol on CYP1A1 XRE transactivation --- p.97
Chapter VI. --- Cytotoxic effect of perillyl alcohol and limonene on MCF-7 cells --- p.98
Chapter VII. --- Perillyl alcohol and limonene modulated UGT1A1 gene expression in MCF-7 cells --- p.99
Chapter VIII. --- Perillyl alcohol and limonene modulated UGT enzyme in HepG2 cells --- p.101
Chapter Part Three --- Discussion --- p.106
Chapter CHAPTER 5 --- LYCOPENE MEDIATED DMBA-INDUCED PHASE I & PHASE II ENZYME ACTIVITIES AND GENE EXPRESSIONS
Chapter Part Three --- Introduction --- p.109
Chapter I. --- Biochemical properties of lycopene --- p.109
Chapter II. --- Bioavailability of lycopene --- p.110
Chapter III. --- Lycopene and cancers in hormonal sensitive tissues --- p.110
Chapter Part Two --- Results --- p.111
Chapter I . --- Lycopene modulated DMBA-induced CYP1A1/1B1 activities in MCF-7 cells --- p.111
Chapter II. --- Lycopene competitively inhibited microsomal CYP1A1 & CYP1B1 activities --- p.113
Chapter III. --- Lycopene suppressed DMBA-induced DNA adduct formation in MCF-7 cells --- p.115
Chapter IV. --- Lycopene regulated CYP1A1 & CYP1B1 gene expression in MCF-7 cells --- p.116
Chapter V. --- Effect of lycopene on CYP1A1 XRE trasactivation --- p.117
Chapter VI. --- Cytotoxic effect of lycopene on MCF-7 cells --- p.118
Chapter VII. --- Lycopene modulated UGT enzyme in MCF-7 cells --- p.119
Chapter VIII. --- Lycopene modulated UGT enzyme in HepG2 cells --- p.121
Chapter Part Three --- Discussion --- p.123
Chapter CHAPTER 6 --- CHALCONES AND PERILLYL ALCOHOL REGULATEDCYP1A1 & CYP1B1 MEDIATED ESTRADIOL METABOLIZING PATHWAYS
Chapter Part One --- Introduction --- p.125
Chapter I . --- Estrogen hydroxylation and human breast cancer risk --- p.125
Chapter II. --- CYP1 enzymes catalyze estradiol-hydroxylation in human breast cancer cells --- p.126
Chapter III. --- Phytochemicals mediate estrogen-hydroxylation pathways --- p.126
Chapter Part Two --- Estrogen metabolite detection and separation by HPLC --- p.127
Chapter Part Three --- Results --- p.129
Chapter I . --- Perillyl alcohol modulated CYP1A1 & CYP1B1-mediated Estradiol hydroxylation --- p.129
Chapter II. --- Kinetics assays of chalcones on CYP1A1 & CYP1B1 microsomes induced estradiol hydroxylation --- p.131
Chapter III. --- Chalcones suppressed Estradiol-hydroxylase activities in MCF-7 cells --- p.137
Chapter Part Four --- Discussion --- p.140
Chapter CHAPTER 7 --- SUMMARY
Chapter I . --- Chalcones displayed inhibitory effects on DMBA-induced carcinogenesis --- p.142
Chapter II. --- Perillyl alcohol and limonene modulated DMBA-induced carcinogenesis --- p.143
Chapter III. --- Lycopene also possessed chemoproventive properties --- p.143
APPENDIX 1 ABBREVIATIONS --- p.144
APPENDIX 2 REAGENTS --- p.145
APPENDIX 3 PRIMER LISTS --- p.147
REFERENCE --- p.148

Lee Kai Woo.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (leaves 90-104).
Abstracts in English and Chinese.
Acknowledgements --- p.ii
Thesis Committee --- p.iii
Abstracts --- p.v
論文槪要 --- p.vii
List of figures --- p.viii
List of abbreviations --- p.ix
Chapter Chapter one --- Introduction --- p.1
Chapter 1.1 --- Drug metabolism and UGTs --- p.1
Chapter 1.2 --- Natural substrates of UGTs --- p.4
Chapter 1.3 --- Functions of UGT isoforms: roles of UGT polymorphisms --- p.6
Chapter 1.4 --- Evolution of the UGT1 gene locus in vertebrates --- p.8
Chapter 1.5 --- Multiple Variable First Exons: A Mechanism for Cell- and Tissue-Specific Gene regulation --- p.13
Chapter 1.6 --- Evolutionary Origin of the Variable and Constant Genomic Organization --- p.14
Chapter 1.7 --- Variable and Constant Genomic Organizations Exist in Mammalian UGTs --- p.20
Chapter 1.8 --- The history of recombinant UGT expression --- p.20
Chapter 1.9 --- UGT1A8 --- p.21
Chapter 1.10 --- Licorice and its active component --- p.24
Chapter 1.11 --- Enzyme induction in the liver --- p.25
Chapter 1 12 --- Objectives --- p.28
Chapter Chapter two --- Methods and Materials --- p.29
Chapter 2.1 --- UGT1A8 induction studies --- p.30
Chapter 2.1.1 --- Drug preparation --- p.30
Chapter 2.1.2 --- Cell viability study with Neutral Red Assay Rat treatment --- p.30
Chapter 2.1.3 --- Cell treatment --- p.31
Chapter 2.1.4 --- Rat treatment --- p.31
Chapter 2.1.5 --- RNA extraction from rat liver and cell culture --- p.31
Chapter 2.1.6 --- Quantization of RNA --- p.32
Chapter 2.1.7 --- Denaturing gel electrophoresis for RNA --- p.33
Chapter 2.1.8 --- Northern hybridization --- p.33
Chapter 2.1.9 --- Probe for Northern Blotting --- p.34
Chapter 2.1.10 --- Agarose Gel analysis and Northern Blot analysis --- p.34
Chapter 2.2 --- Recombinant expression of UGT1A8 in E.coli JM109 --- p.35
Chapter 2.2.1 --- cDNA synthesis --- p.35
Chapter 2.2.2 --- Polymerase chain reaction --- p.35
Chapter 2.2.3 --- Agarose gel electrophoresis for DNA --- p.35
Chapter 2.2.4 --- "Amplification of target gene, UGT1A8" --- p.36
Chapter 2.2.5 --- Restriction enzyme digestion of plasmid and insert --- p.36
Chapter 2.2.6 --- Ligation of plasmid and insert DNA --- p.37
Chapter 2.2.7 --- Amplification of target plasmid --- p.37
Chapter 2.2.8 --- Screening of target plasmid --- p.37
Chapter 2.2.9 --- DNA sequencing --- p.38
Chapter 2.2.10 --- Transformation of protein expression host --- p.38
Chapter 2.2.11 --- Confirmation of transformation of protein expression host --- p.38
Chapter 2.2.12 --- Protein expression --- p.39
Chapter 2.2.13 --- Protein purification --- p.39
Chapter 2.2.14 --- Sodium dodecyl sulfate polyacrylamide gel electrophoresis --- p.40
Chapter 2.2.15 --- Confirmation of the protein --- p.40
Chapter 2.3 --- Characterization of recombinant UGT1A8 --- p.41
Chapter 2.3.1 --- UGT assay --- p.41
Chapter 2.4 --- Routine experiment methods --- p.41
Chapter 2.4.1 --- Determination of protein --- p.41
Chapter 2.4.2 --- Nucleic acid purification --- p.42
Chapter 2.4.3 --- Preparation of chemically competent bacterial cells --- p.42
Chapter 2.4.4 --- Colony PCR --- p.43
Chapter 2.4.5 --- Plasmid rescue by alkaline lysis --- p.44
Chapter 2.4.6 --- Charging of His-tagged column --- p.44
Chapter 2.4.7 --- Washing of His-tagged column --- p.45
Chapter Chapter three --- Results --- p.46
Chapter 3.1 --- UGT1A8 Expression in clone9 and H4IIE after treatment with licorice and 18 β glycyrrhentinic acid --- p.46
Chapter 3.2 --- UGT1A8 induction in wistar and j/j rats after treatment --- p.63
Chapter 3.3 --- Construction of pRset-UGT 1A8 Vector --- p.70
Chapter 3.4 --- Purification of recombinant UGT1A8 --- p.75
Chapter 3.5 --- Screening of substrate of the purified enzyme --- p.77
Chapter Chapter four --- Discussion --- p.78
Chapter 4.1 --- Effects of licorice and 18βglycyrrhetinic acid in the induction of UGT1A8 in different cell lines --- p.78
Chapter 4.2 --- Comparison of wistar and j/j rats in the induction of UGT1A8 --- p.79
Chapter 4.3 --- Comparison of licorice and 18(3 glycyrrhetinic acid in the induction of UGT1A8 in rats --- p.81
Chapter 4.4 --- Comparison of in vivo and in vitro of drug treatment --- p.81
Chapter 4.5 --- Expression of UGT1A7 after drug treatment in vitro --- p.82
Chapter 4.6 --- Protein expression and purification --- p.83
Chapter 4.7 --- Substrates of UGT1A8 --- p.83
Chapter Chapter Five --- Conclusions --- p.86
References --- p.90
Appendix --- p.105

Based on reactions with two flavanones, three flavonols, and five flavones the regioselectivities of twelve human UDP-glucuronosyltransferase (UGT) isozymes were elucidated. The various flavonoid glucuronides were differentiated based on LC-MS/MS fragmentation patterns of [Co(II)(flavonoid – H)(4,7-diphenyl-1,10-phenanthroline)2]+ complexes generated upon post-column complexation. Glucuronide distributions were evaluated to allow a systematic assessment of the regioselectivity of each isozyme. The various UGT enzymes, including eight UGT1A and four UGT2B, displayed a remarkable range of selectivities, both in terms of the positions of glucuronidation and relative reactivity with flavanones, flavonols and flavones. The UGT1A enzyme selectivities are affected by the presence of a hydroxyl group at the 3, 6, 4’, or 3’ positions as well as by the presence of a methoxy at the 3’ position. The UGT2B enzymes show poor to no reactivity with the flavonols or flavones. This result implies that the greater planarity of the flavonols and flavones compared to structure of flavanones inhibits interaction with the UGT2 enzymes. For baicalein and scutellarein, three of the UGT1A isozymes (1A8, 1A9, and 1A10) resulted in the formation of 6-O glucuronides, enabling the fragmentation rules for the metal complexation/MS/MS strategy to be expanded.
text

This thesis focuses on the importance of the heme catabolic pathway in chronic hepatitis C (HCV). The aim is mainly to investigate, whether expresion/activity of key enzymes of the heme catabolic pathway, heme oxygenase (HMOX) and biliverdin reductase (BLVRA) in the liver and blood (study A) or promoter variations of HMOX1 and UDP- glucuronosyltransferase (UGT1A1) (study B) may be associated with the progression of fibrosis and may also predict antiviral treatment outcome in patients chronically infected with HCV. We set up a new sensitive method to quantify HMOX activity by reduction gas chromatography. We developed and extensively validated RealTime PCR assay for HMOX and BLVRA expression in the liver and peripheral blood leucocytes (PBL). The (GT)n and (TA)n dinucleotide variations in HMOX1 and UGT1A1 gene promoters, respectively, were determined by fragment analysis. No association was detected between either expression of HMOX/BLVRA or the HMOX1/ UGT1A1 promoter variants and the individual histological stages of liver disease in the HCV positive patients. A marked difference in BLVRA expression in PBL between the sustained responders (SVR) and patients with treatment failure (NVR) was detected before antiviral treatment and during the follow-up. Our data suggests, that BLVRA basal expression...

博士
國防醫學院
醫學科學研究所
101
Chapter I. The Study of Cellular MicroRNA Expression Regulated by Hepatitis C Virus Core Protein in Human Hepatoma Cell Lines Chronic hepatitis C virus (HCV) infection contributes to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma, but the molecular pathogenesis is still unclear. HCV infection has been reported to modulate cellular microRNA (miRNA) expression. HCV core protein is believed to be involved in hepatocarcinogenesis by directly and indirectly regulating gene transcription, interfering with cellular signaling pathways, and affecting cell cycle and apoptosis. The full-length core protein is mainly found within the membranes of cytoplasmic organelles, whereas the mature form is trafficked to the nucleus. In this study, we examined miRNA expression profile in Huh7 cells transiently expressing full-length and mature HCV core protein using TaqMan low density array. Array data were further determined in Huh7 and HepG2 cells overexpressing full-length and mature core protein and in Huh7 cells expressing full-length HCV replicon. We demonstrate that the mature core protein modulates miR-345，miR-93，miR-138及miR-192 expression, and the full-length core protein modulates miR-192 expression. MiR-345 down-regulates p21Waf1/Cip1 gene expression by directly targeting its 3’ untranslated region (3’UTR). MiR-138 and miR-192 down-regulate telomerase reverse transcriptase (hTERT) and SIP1 gene expressions through directly targeting on their 3’ untranslated regions respectively. HCV core-induced miR-345 inhibits apoptosis through down-regulation of p21Waf1/Cip1 gene expression. Furthermore, the core protein regulates miR-138 and miR-192 expression to suppress cell proliferation by directly and indirectly inhibiting hTERT gene expression. This study may explain, in part, the molecular pathogenesis of multistep hepatocarcinogenesis during chronic HCV infection. Chapter II. The Investigation of the Effect of Inflammation on the Expression of Human UDP-Glucuronosyltransferase 1A1 Gene Jaundice or hyperbilirubinemia is a common complication of sepsis. However, the molecular pathogenesis of hyperbilirubinemia during inflammation needs to be further clarified. UDP-glucuronosyltransferase 1A1 (UGT1A1) is a key enzyme for bilirubin metabolism. In this study, C57BL/6J mice were injected intraperitoneally with lipopolysaccharide (LPS). LPS suppresses mouse hepatic UGT1A1 gene expression, leading to the increases of total bilirubin and unconjugated bilirubin. Furthermore, human hepatic UGT1A1 gene expression is inhibited in Huh7 and HepG2 cells in response to LPS stimulation. We analyzed the upstream promiter region of human UGT1A1 gene using Transcriptional Regulatory Element Database. A novel NF-κB-binding site (-725/-716) in human UGT1A1 promoter region was determined using electrophoretic mobility shift assay and chromatin immunoprecipitation. We showed that NF-κB activation is associated with down-regulation of UGT1A1 gene expression in Huh7 and HepG2 cells in response to LPS stimulation. Moreover, we further demonstrate that LPS suppresses human hepatic UGT1A1 gene expression through directly binding of NF-κB to this novel identified NF-κB-binding site (-725/-716) in the upstream promoter region of human UGT1A1 gene. This study may partly explain the molecular pathogenesis of inflammation-associated hyperbilirubinemia.