Gonzalez FJ

References (17)

Title : Microbial-host-isozyme analyses reveal microbial DPP4 as a potential antidiabetic target - Wang_2023_Science_381_eadd5787
Author(s) : Wang K , Zhang Z , Hang J , Liu J , Guo F , Ding Y , Li M , Nie Q , Lin J , Zhuo Y , Sun L , Luo X , Zhong Q , Ye C , Yun C , Zhang Y , Wang J , Bao R , Pang Y , Wang G , Gonzalez FJ , Lei X , Qiao J , Jiang C
Ref : Science , 381 :eadd5787 , 2023
Abstract : A mechanistic understanding of how microbial proteins affect the host could yield deeper insights into gut microbiota-host cross-talk. We developed an enzyme activity-screening platform to investigate how gut microbiota-derived enzymes might influence host physiology. We discovered that dipeptidyl peptidase 4 (DPP4) is expressed by specific bacterial taxa of the microbiota. Microbial DPP4 was able to decrease the active glucagon like peptide-1 (GLP-1) and disrupt glucose metabolism in mice with a leaky gut. Furthermore, the current drugs targeting human DPP4, including sitagliptin, had little effect on microbial DPP4. Using high-throughput screening, we identified daurisoline-d4 (Dau-d4) as a selective microbial DPP4 inhibitor that improves glucose tolerance in diabetic mice.
ESTHER : Wang_2023_Science_381_eadd5787
PubMedSearch : Wang_2023_Science_381_eadd5787
PubMedID: 37535747
Gene_locus related to this paper: bactn-BT4193

Title : Role of white adipose lipolysis in the development of NASH induced by methionine- and choline-deficient diet - Tanaka_2014_Biochim.Biophys.Acta_1841_1596
Author(s) : Tanaka N , Takahashi S , Fang ZZ , Matsubara T , Krausz KW , Qu A , Gonzalez FJ
Ref : Biochimica & Biophysica Acta , 1841 :1596 , 2014
Abstract : Methionine- and choline-deficient diet (MCD) is a model for nonalcoholic steatohepatitis (NASH) in rodents. However, the mechanism of NASH development by dietary methionine/choline deficiency remains undetermined. To elucidate the early metabolic changes associated with MCD-NASH, serum metabolomic analysis was performed using mice treated with MCD and control diet for 3 days and 1 week, revealing significant increases in oleic and linoleic acids after MCD treatment. These increases were correlated with reduced body weight and white adipose tissue (WAT) mass, increased phosphorylation of hormone-sensitive lipase, and up-regulation of genes encoding carboxylesterase 3 and beta2-adrenergic receptor in WAT, indicating accelerated lipolysis in adipocytes. The changes in serum fatty acids and WAT by MCD treatment were reversed by methionine supplementation, and similar alterations were detected in mice fed a methionine-deficient diet (MD), thus demonstrating that dietary methionine deficiency enhances lipolysis in WAT. MD treatment decreased glucose and increased fibroblast growth factor 21 in serum, thus exhibiting a similar metabolic phenotype as the fasting response. Comparison between MCD and choline-deficient diet (CD) treatments suggested that the addition of MD-induced metabolic alterations, such as WAT lipolysis, to CD-induced hepatic steatosis promotes liver injury. Collectively, these results demonstrate an important role for dietary methionine deficiency and WAT lipolysis in the development of MCD-NASH.
ESTHER : Tanaka_2014_Biochim.Biophys.Acta_1841_1596
PubMedSearch : Tanaka_2014_Biochim.Biophys.Acta_1841_1596
PubMedID: 25178843

Title : Metabolomics identifies an inflammatory cascade involved in dioxin- and diet-induced steatohepatitis - Matsubara_2012_Cell.Metab_16_634
Author(s) : Matsubara T , Tanaka N , Krausz KW , Manna SK , Kang DW , Anderson ER , Luecke H , Patterson AD , Shah YM , Gonzalez FJ
Ref : Cell Metab , 16 :634 , 2012
Abstract : 2,3,7,8-Tetrachlorodibenzo-p-dioxin TCDD is among the most potent environmentally toxic compounds Serum metabolomics identified azelaic acid monoesters as significantly increased metabolites after TCDD treatment due to downregulation of hepatic carboxylesterase 3 CES3 also known as triglyceride hydrolase expression in an arylhydrocarbon receptor AhR)-dependent manner in mice The decreased CES3 expression was accomplished by TCDD-stimulated TGFbeta-SMAD3 and IL6-STAT3 signaling but not by direct AhR signaling Methionine and choline-deficient MCD diet-treated mice also showed enhanced serum azelaic acid monoester levels after attenuation of hepatic CES3 expression while db/db mice did not thus suggesting an association with steatohepatitis Forced expression of CES3 reversed serum azelaic acid monoester/azelaic acid ratios and hepatic TGFbeta mRNA levels in TCDD and MCD diet-treated mice and ameliorated steatohepatitis induced by MCD diet These results support the view that azelaic acid monoesters are possible indicators of TCDD exposure and steatohepatitis and suggest a link between CES3 TGFbeta and steatohepatitis.
ESTHER : Matsubara_2012_Cell.Metab_16_634
PubMedSearch : Matsubara_2012_Cell.Metab_16_634
PubMedID: 23140643

Title : PPARgamma in the endothelium regulates metabolic responses to high-fat diet in mice - Kanda_2009_J.Clin.Invest_119_110
Author(s) : Kanda T , Brown JD , Orasanu G , Vogel S , Gonzalez FJ , Sartoretto J , Michel T , Plutzky J
Ref : J Clinical Investigation , 119 :110 , 2009
Abstract : Although endothelial dysfunction, defined as abnormal vasoreactivity, is a common early finding in individuals with type 2 diabetes, the endothelium has not been known to regulate metabolism. As PPARgamma, a transcriptional regulator of energy balance, is expressed in endothelial cells, we set out to investigate the role of endothelial cell PPARgamma in metabolism using mice that lack PPARgamma in the endothelium and BM (gammaEC/BM-KO). When gammaEC/BM-KO mice were fed a high-fat diet, they had decreased adiposity and increased insulin sensitivity compared with control mice, despite increased serum FFA and triglyceride (TG) levels. After fasting or olive oil gavage, gammaEC/BM-KO mice exhibited significant dyslipidemia and failed to respond to the FFA and TG lowering effects of the PPARgamma agonist rosiglitazone. BM transplantation studies, which reconstituted hematopoietic PPARgamma, established that these metabolic phenotypes were due to endothelial PPARgamma deficiency. We further found that the impairment in TG-rich lipoprotein metabolism in gammaEC/BM-KO mice was associated with fatty acid-mediated lipoprotein lipase inhibition and changes in a PPARgamma-regulated endothelial cell transcriptional program. Despite their metabolic improvements, high-fat diet-fed gammaEC/BM-KO mice had impaired vasoreactivity. Taken together, these data suggest that PPARgamma in the endothelium integrates metabolic and vascular responses and may contribute to the effects of PPARgamma agonists, thus expanding what endothelial function and dysfunction may entail.
ESTHER : Kanda_2009_J.Clin.Invest_119_110
PubMedSearch : Kanda_2009_J.Clin.Invest_119_110
PubMedID: 19065047

Title : A chemical-genetic approach to study G protein regulation of beta cell function in vivo - Guettier_2009_Proc.Natl.Acad.Sci.U.S.A_106_19197
Author(s) : Guettier JM , Gautam D , Scarselli M , Ruiz de Azua I , Li JH , Rosemond E , Ma X , Gonzalez FJ , Armbruster BN , Lu H , Roth BL , Wess J
Ref : Proc Natl Acad Sci U S A , 106 :19197 , 2009
Abstract : Impaired functioning of pancreatic beta cells is a key hallmark of type 2 diabetes. beta cell function is modulated by the actions of different classes of heterotrimeric G proteins. The functional consequences of activating specific beta cell G protein signaling pathways in vivo are not well understood at present, primarily due to the fact that beta cell G protein-coupled receptors (GPCRs) are also expressed by many other tissues. To circumvent these difficulties, we developed a chemical-genetic approach that allows for the conditional and selective activation of specific beta cell G proteins in intact animals. Specifically, we created two lines of transgenic mice each of which expressed a specific designer GPCR in beta cells only. Importantly, the two designer receptors differed in their G protein-coupling properties (G(q/11) versus G(s)). They were unable to bind endogenous ligand(s), but could be efficiently activated by an otherwise pharmacologically inert compound (clozapine-N-oxide), leading to the conditional activation of either beta cell G(q/11) or G(s) G proteins. Here we report the findings that conditional and selective activation of beta cell G(q/11) signaling in vivo leads to striking increases in both first- and second-phase insulin release, greatly improved glucose tolerance in obese, insulin-resistant mice, and elevated beta cell mass, associated with pathway-specific alterations in islet gene expression levels. Selective stimulation of beta cell G(s) triggered qualitatively similar in vivo metabolic effects. Thus, this developed chemical-genetic strategy represents a powerful approach to study G protein regulation of beta cell function in vivo.
ESTHER : Guettier_2009_Proc.Natl.Acad.Sci.U.S.A_106_19197
PubMedSearch : Guettier_2009_Proc.Natl.Acad.Sci.U.S.A_106_19197
PubMedID: 19858481

Title : Regulation of insulin-like growth factor binding protein-1 and lipoprotein lipase by the aryl hydrocarbon receptor - Minami_2008_J.Toxicol.Sci_33_405
Author(s) : Minami K , Nakajima M , Fujiki Y , Katoh M , Gonzalez FJ , Yokoi T
Ref : Journal of Toxicological Sciences , 33 :405 , 2008
Abstract : The aryl hydrocarbon receptor (Ahr), a ligand-activated transcriptional factor, mediates the transcriptional activation of a battery of genes encoding drug metabolism enzymes. In the present study, we investigated the hepatic mRNA expression profile in Ahr-null (Ahr KO) mice compared to wild-type mice by microarray analysis to find new Ahr target genes. Pooled total RNA samples of liver extracted from 7- and 60-week-old Ahr KO or wild-type mice were studied by DNA microarray representing 19,867 genes. It was demonstrated that 23 genes were up-regulated and 20 genes were down-regulated over 2 fold in Ahr KO mice compared with wild-type mice commonly within the different age groups. We focused on insulin-like growth factor binding protein-1 (Igfbp-1) and lipoprotein lipase (Lpl) that were up-regulated in Ahr KO mice. The higher expression in Ahr KO mice compared to wild-type mice were confirmed by real-time RT-PCR analysis. In the wild-type mice but not in the Ahr KO mice, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treatment increased the Igfbp-1 and Lpl mRNA levels. The expression profile of Igfbp-1 protein was consistent with that of Igfbp-1 mRNA. Since Lpl is the primary enzyme responsible for hydrolysis of lipids in lipoproteins, the serum triglyceride levels were determined. Indeed, the serum triglyceride levels in Ahr KO mice was lower than that in wild-type mice in accordance with the Lpl mRNA levels. Contrary to our expectation, TCDD treatment significantly increased the serum triglyceride levels in wild-type, but did not in Ahr KO mice. These results suggest that serum triglyceride levels are not correlated with hepatic Lpl expression levels. In the present study, we found that Ahr paradoxically regulates Igfbp-1 and Lpl expressions in the liver.
ESTHER : Minami_2008_J.Toxicol.Sci_33_405
PubMedSearch : Minami_2008_J.Toxicol.Sci_33_405
PubMedID: 18827440

Title : Male mice deficient in microsomal epoxide hydrolase are not susceptible to benzene-induced toxicity - Bauer_2003_Toxicol.Sci_72_201
Author(s) : Bauer AK , Faiola B , Abernethy DJ , Marchan R , Pluta LJ , Wong VA , Gonzalez FJ , Butterworth BE , Borghoff SJ , Everitt JI , Recio L
Ref : Toxicol Sci , 72 :201 , 2003
Abstract : Enzymes involved in benzene metabolism are likely genetic determinants of benzene-induced toxicity. Polymorphisms in human microsomal epoxide hydrolase (mEH) are associated with an increased risk of developing leukemia, specifically those associated with benzene. This study was designed to investigate the importance of mEH in benzene-induced toxicity. Male and female mEH-deficient (mEH-/-) mice and background mice (129/Sv) were exposed to inhaled benzene (0, 10, 50, or 100 ppm) 5 days/week, 6 h/day, for a two-week duration. Total white blood cell counts and bone marrow cell counts were used to assess hematotoxicity and myelotoxicity. Micronucleated peripheral blood cells were counted to assess genotoxicity, and the p21 mRNA level in bone marrow cells was used as a determinant of the p53-regulated DNA damage response. Male mEH-/- mice did not have any significant hematotoxicity or myelotoxicity at the highest benzene exposure compared to the male 129/Sv mice. Significant hematotoxicity or myelotoxicity did not occur in the female mEH-/- or 129/Sv mice. Male mEH-/- mice were also unresponsive to benzene-induced genotoxicity compared to a significant induction in the male 129/Sv mice. The female mEH-/- and 129/Sv mice were virtually unresponsive to benzene-induced genotoxicity. While p21 mRNA expression was highly induced in male 129/Sv mice after exposure to 100-ppm benzene, no significant alteration was observed in male mEH-/- mice. Likewise, p21 mRNA expression in female mEH-/- mice was not significantly induced upon benzene exposure whereas a significant induction was observed in female 129/Sv mice. Thus mEH appears to be critical in benzene-induced toxicity in male, but not female, mice.
ESTHER : Bauer_2003_Toxicol.Sci_72_201
PubMedSearch : Bauer_2003_Toxicol.Sci_72_201
PubMedID: 12655032

Title : Relative importance of maternal and embryonic microsomal epoxide hydrolase in 7,12-dimethylbenz[a]anthracene-induced developmental toxicity - Miyata_2002_Biochem.Pharmacol_63_1077
Author(s) : Miyata M , Motoki K , Tamura E , Furukawa M , Gonzalez FJ , Yamazoe Y
Ref : Biochemical Pharmacology , 63 :1077 , 2002
Abstract : Microsomal epoxide hydrolase (mEH) catalyzes the hydrolysis of epoxide intermediates derived from drugs and environmental chemicals. The response of in vivo (embryo) and in vitro (embryo fibroblast) tests were analyzed using mEH-null and wild-type mice to determine the relative role of maternal and embryonic mEH in the developmental toxicity induced by 7,12-dimethylbenz[a]anthracene (DMBA). Embryos derived from DMBA-treated [50mg/kg, daily from gestational day (GD) 11 to GD 15] dams were analyzed. Although weight (P=0.0009) and crown-rump length (P=0.0003) of wild-type fetuses on GD 18 were significantly lower than those of mEH-null fetuses, respectively, no significant difference was found between mEH-null and heterozygous fetuses of mEH-null dams. Cell viability was decreased to 50% in wild-type mouse embryo fibroblasts (MEFs) treated with 3 microM DMBA, but no significant decrease was found in mEH-null MEFs. DMBA-3,4-diol produced a significant decrease in cell viability and suppressed the proliferation of wild-type MEFs at a 10-fold lower concentration than did DMBA. Although mEH protein was expressed in liver microsomes from wild-type embryos (GD 15), DMBA-3,4-diol was not detected among the DMBA metabolites. However, it was detected in the serum of wild-type pregnant mice treated with DMBA, but not in that of mEH-null mice. These results suggest that maternal mEH plays a major role in DMBA-induced developmental toxicity, and embryonic mEH is less involved in the toxicity.
ESTHER : Miyata_2002_Biochem.Pharmacol_63_1077
PubMedSearch : Miyata_2002_Biochem.Pharmacol_63_1077
PubMedID: 11931840

Title : The use of gene knockout mice to unravel the mechanisms of toxicity and chemical carcinogenesis - Gonzalez_2001_Toxicol.Lett_120_199
Author(s) : Gonzalez FJ
Ref : Toxicol Lett , 120 :199 , 2001
Abstract : Metabolism of toxins and carcinogens is carried out by large groups of xenobiotic-metabolizing enzymes. These enzymes are generally considered to be required for elimination of xenobiotics such as drugs, dietary chemicals and environmental pollutants, and to be required for chemical toxicity and carcinogenicity. An important role for these enzymes in metabolism of endogenous chemicals has not been established. Mouse lines in which the genes encoding several xenobiotic-metabolizing enzymes were knocked out were produced and are being used to determine the role of metabolism in carcinogenesis, and acute and chronic toxicities in vivo. Mouse lines lacking the P450s CYP1A1, CYP1A2, CYP1B1 and CYP2E1, microsomal epoxide hydrolase (mEH), NADPH:quinone oxidoreductase and the glutathione S-transferase P1 have no deleterious phenotypes, indicating that these enzymes are not required for mammalian development and physiological homeostasis. However, when challenged with toxins and carcinogens, they respond differently from their wild-type (WT) counterparts. For example, mice lacking CYP1A2 and CYP2E1 are totally resistant to acetaminophen-induced hepatotoxicity. Mice lacking CYP1B1 or mEH are less responsive to tumorigenesis by 7,12-dimethybenz[a]anthracene. However, CYP1A2-null mice do not significantly differ from WT mice in their response to the hepatocarcinogen 4-aminobiphenyl. These and other studies indicate that the xenobiotic-metabolism null mice are of great value in the study of the mechanisms of chemical injury.
ESTHER : Gonzalez_2001_Toxicol.Lett_120_199
PubMedSearch : Gonzalez_2001_Toxicol.Lett_120_199
PubMedID: 11323178

Title : Understanding the role of xenobiotic-metabolism in chemical carcinogenesis using gene knockout mice - Gonzalez_2001_Mutat.Res_477_79
Author(s) : Gonzalez FJ , Kimura S
Ref : Mutat Res , 477 :79 , 2001
Abstract : Most chemical carcinogens require metabolic activation to electrophilic metabolites that are capable of binding to DNA and causing gene mutations. Carcinogen metabolism is carried out by large groups of xenobiotic-metabolizing enzymes that include the phase I cytochromes P450 (P450) and microsomal epoxide hydrolase, and various phase II transferase enzymes. It is extremely important to determine the role P450s play in the carcinogenesis and to establish if they are the rate limiting and critical interface between the chemical and its biological activities. The latter is essential in order to validate the use of rodent models to test safety of chemicals in humans. Since there are marked species differences in expressions and catalytic activities of the multiple P450 forms that activate carcinogens, this validation process becomes especially difficult. To address the role of P450s in whole animal carcinogenesis, mice were produced that lack the P450s known to catalyze carcinogen activation. Mouse lines having disrupted genes encoding the P450s CYP1A2, CYP2E1, and CYP1B1 were developed. Mice lacking expression of microsomal epoxide hydrolase (mEH) and NADPH-quinone oxidoreductase (NQO1) were also made. All of these mice exhibit no gross abnormal phenotypes, suggesting that the xenobiotic-metabolizing enzymes have no critical roles in mammalian development and physiological homeostasis. This explains the occurrence of polymorphisms in xenobiotic-metabolizing enzymes among humans and other mammalian species. However, these null mice do show differences in sensitivities to acute chemical toxicities, thus establishing the importance of xenobiotic metabolism in activation pathways that lead to cell death. Rodent bioassays using null mice and known genotoxic carcinogens should establish whether these enzymes are required for carcinogenesis in an intact animal model. These studies will also provide a framework for the production of transgenic mice and carcinogen bioassay protocols that may be more predictive for identifying the human carcinogens and validate the molecular epidemiological studies ongoing in humans that seek to establish a role for polymorphisms in cancer risk.
ESTHER : Gonzalez_2001_Mutat.Res_477_79
PubMedSearch : Gonzalez_2001_Mutat.Res_477_79
PubMedID: 11376689

Title : Mechanism of 7,12-dimethylbenz[a]anthracene-induced immunotoxicity: role of metabolic activation at the target organ - Miyata_2001_Jpn.J.Pharmacol_86_302
Author(s) : Miyata M , Furukawa M , Takahashi K , Gonzalez FJ , Yamazoe Y
Ref : Japanese Journal of Pharmacology , 86 :302 , 2001
Abstract : The polycyclic aromatic hydrocarbon, 7,12-dimethylbenz[a]anthracene (DMBA), is an immunosuppressor as well as a potent organ-specific carcinogen. To understand the organ-specific mechanism of DMBA-induced lymphoid toxicity, aryl hydrocarbon-nonresponsive mice and microsomal epoxide hydrolase (mEH)-null mice were analyzed. DMBA caused a dose-dependent decrease in spleen weights, but not the thymus weights in aryl hydrocarbon-nonresponsive mice. On the other hand, both spleen and thymus weights were decreased to less than a half in wild-type mice exposed to 30 mg/kg of DMBA. In contrast, no decrease was detected in spleen weights of mEH-null mice exposed to up to 100 mg/kg of DMBA, while thymus weights were markedly lower. Responses to the B-cell mitogen lipopolysaccharide and to T-cell mitogen phytohemagglutinin were nearly completely abolished in splenocytes isolated from wild-type mice treated with 100 mg/kg of DMBA. These responses were decreased, but maintained in splenocytes isolated from mEH-null mice treated with DMBA. Two DMBA metabolites dependent on mEH including DMBA-3,4-diol were detected in an HPLC chromatogram of spleen microsomes isolated from wild-type mice, but not those from mEH-null mice. These results suggest the involvement of mEH in splenic activation of DMBA for immunotoxicity and the difference for the DMBA-induced lymphoid toxicity between spleen and thymus.
ESTHER : Miyata_2001_Jpn.J.Pharmacol_86_302
PubMedSearch : Miyata_2001_Jpn.J.Pharmacol_86_302
PubMedID: 11488430

Title : Targeted disruption of soluble epoxide hydrolase reveals a role in blood pressure regulation - Sinal_2000_J.Biol.Chem_275_40504
Author(s) : Sinal CJ , Miyata M , Tohkin M , Nagata K , Bend JR , Gonzalez FJ
Ref : Journal of Biological Chemistry , 275 :40504 , 2000
Abstract : Renal microsomal cytochrome P-450 monooxygenase-dependent metabolism of arachidonic acid generates a series of regioisomeric epoxyeicosatrienoic acids that can be further metabolized by soluble epoxide hydrolase to the corresponding dihydroxyeicosatrienoic acids. Evidence exists that these metabolites affect renal function and, in particular, blood pressure regulation. To examine this possibility, blood pressure and renal arachidonic acid metabolism were examined in mice with a targeted disruption of the soluble epoxide hydrolase gene. Systolic blood pressure of male soluble epoxide hydrolase-null mice was lower compared with wild-type mice in both the absence and presence of dietary salt loading. Both female soluble epoxide hydrolase-null and wild-type female mice also had significantly lower systolic blood pressure than male wild-type mice. Renal formation of epoxyeicosatrienoic and dihydroxyeicosatrienoic acids was markedly lower for soluble epoxide hydrolase-null versus wild-type mice of both sexes. Although disruption of soluble epoxide hydrolase in female mice had minimal effects on blood pressure, deletion of this gene feminized male mice by lowering systolic blood pressure and altering arachidonic acid metabolism. These data provide the first direct evidence for a role for soluble epoxide hydrolase in blood pressure regulation and identify this enzyme as a novel and attractive target for therapeutic intervention in hypertension.
ESTHER : Sinal_2000_J.Biol.Chem_275_40504
PubMedSearch : Sinal_2000_J.Biol.Chem_275_40504
PubMedID: 11001943

Title : Role of gene knockout mice in understanding the mechanisms of chemical toxicity and carcinogenesis - Gonzalez_1999_Cancer.Lett_143_199
Author(s) : Gonzalez FJ , Kimura S
Ref : Cancer Letters , 143 :199 , 1999
Abstract : Most chemical carcinogens require metabolic activation to electrophilic metabolites that are capable of binding to DNA and causing gene mutation. Carcinogen metabolism is carried out by large groups of xenobiotic-metabolizing enzymes that include the phase I cytochromes P450 (P450) and phase II enzymes that include various transferases. During the past 10 years, considerable attention has been focused on the role of P450s in human cancer susceptibility. Polymorphisms in expression of P450s and transferases exist in humans and these might render increased susceptibility or resistance to cancer. Thus it is important to understanding how P450s participate in the carcinogenesis process and to determine if they are indeed the rate limiting and critical interface between the chemical and its biological activity. Since there are marked species differences in expressions and catalytic activities of the multiple P450 forms that activate carcinogens, this validation process becomes especially difficult. To address the role of P450s in whole animal carcinogenesis, mice were produced that lack the P450s known to catalyze carcinogen activation. Mouse lines having disruption of genes encoding P450s CYP1A2, CYP2E1, and CYP1B1 were developed by use of gene disruption in empbryonic stem cells. Mice lacking expression of microsomal epoxide hydrolase and NADPH:quinone oxidoreductase were also made. These mice exhibit no grossly abnormal phenotypes, suggesting that the xenobiotic-metabolizing enzymes have no critical roles in mammalian development and physiological homeostasis. This explains the occurrence of polymorphisms in humans and other mammalian species. However, these null mice do show differences in sensitivities to acute chemical toxicities, thus establishing the importance of xenobiotic metabolism in activation pathways that lead to cell death. Rodent bioassays using null mice and known genotoxic carcinogens should establish whether these enzymes are required for carcinogenesis in an intact animal model. These studies will also provide a framework for the production of transgenic mice and carcinogen bioassay protocols that may be more predictive for identifying human carcinogens and validate the molecular epidemiology studies ongoing in humans that seek to establish a role for polymorphisms in cancer risk.
ESTHER : Gonzalez_1999_Cancer.Lett_143_199
PubMedSearch : Gonzalez_1999_Cancer.Lett_143_199
PubMedID: 10503904

Title : Targeted disruption of the microsomal epoxide hydrolase gene. Microsomal epoxide hydrolase is required for the carcinogenic activity of 7,12-dimethylbenz[a]anthracene - Miyata_1999_J.Biol.Chem_274_23963
Author(s) : Miyata M , Kudo G , Lee YH , Yang TJ , Gelboin HV , Fernandez-Salguero P , Kimura S , Gonzalez FJ
Ref : Journal of Biological Chemistry , 274 :23963 , 1999
Abstract : Microsomal epoxide hydrolase (mEH) is a conserved enzyme that is known to hydrolyze many drugs and carcinogens, and a few endogenous steroids and bile acids. mEH-null mice were produced and found to be fertile and have no phenotypic abnormalities thus indicating that mEH is not critical for reproduction and physiological homeostasis. mEH has also been implicated in participating in the metabolic activation of polycyclic aromatic hydrocarbon carcinogens. Embryonic fibroblast derived from the mEH-null mice were unable to produce the proximate carcinogenic metabolite of 7,12-dimethylbenz[a]anthracene (DMBA), a widely studied experimental prototype for the polycylic aromatic hydrocarbon class of chemical carcinogens. They were also resistant to DMBA-mediated toxicity. Using the two-stage initiation-promotion skin cancer bioassay, the mEH-null mice were found to be highly resistant to DMBA-induced carcinogenesis. In a complete carcinogenesis bioassay, the mEH mice were totally resistant to tumorigenesis. These data establish in an intact animal model that mEH is a key genetic determinant in DMBA carcinogenesis through its role in production of the ultimate carcinogenic metabolite of DMBA, the 3,4-diol-1,2-epoxide.
ESTHER : Miyata_1999_J.Biol.Chem_274_23963
PubMedSearch : Miyata_1999_J.Biol.Chem_274_23963
PubMedID: 10446164

Title : Glycosylation-dependent activity of baculovirus-expressed human liver carboxylesterases: cDNA cloning and characterization of two highly similar enzyme forms - Kroetz_1993_Biochemistry_32_11606
Author(s) : Kroetz DL , McBride OW , Gonzalez FJ
Ref : Biochemistry , 32 :11606 , 1993
Abstract : A cDNA, designated hCE, encoding the entire sequence of a carboxylesterase, was isolated from a human liver lambda gt11 library. The hCE-deduced protein sequence contained 568 amino acids, including an 18 amino acid signal peptide sequence, and had a calculated molecular mass of the mature protein of 60,609 Da. A second cDNA, designated hCEv, was isolated from the same lambda gt11 library and contained a 3-bp deletion resulting in the loss of the final amino acid in the signal peptide sequence (Ala-1) and a second 3-bp deletion leading to an in-frame loss of Gln345. Expression of mRNA corresponding to both hCE and hCEv was detected in eight adult human liver samples, with individual levels varying 5-fold (hCE) and 12-fold (hCEv). A single immunoreactive protein was detected in 13 adult human liver samples when probed with antibody directed against a rat carboxylesterase. Based on allele-specific oligonucleotide hybridizations, we believe that the hCE and hCEv cDNAs represent two distinct members of the carboxylesterase family. The carboxylesterase genes were localized to human chromosome 16 using a somatic cell hybrid mapping strategy. Baculovirus expression of hCE in Sf9 cells produced a protein with an estimated molecular mass of 59,000 Da. This enzyme was able to hydrolyze aromatic and aliphatic esters but possessed no catalytic activity toward amides or a fatty acyl CoA ester. Baculovirus-mediated expression of the hCEv cDNA yielded a second protein of 56,000 Da resulting from inefficient N-glycosylation of the hCEv protein. Although the substrate specificity for the hCEv protein was identical to that of expressed hCE for any given substrate, the specific activity for the hCE protein was always higher than that for the hCEv protein. Tunicamycin inhibition studies provided the first evidence that N-glycosylation of these luminal enzymes is essential for maximal catalytic activity.
ESTHER : Kroetz_1993_Biochemistry_32_11606
PubMedSearch : Kroetz_1993_Biochemistry_32_11606
PubMedID: 8218228
Gene_locus related to this paper: human-CES1

Title : Rat liver carboxylesterase: cDNA cloning, sequencing, and evidence for a multigene family - Long_1988_Biochem.Biophys.Res.Commun_156_866
Author(s) : Long RM , Satoh H , Martin BM , Kimura S , Gonzalez FJ , Pohl LR
Ref : Biochemical & Biophysical Research Communications , 156 :866 , 1988
Abstract : A cDNA clone was isolated from a rat liver lambda gt11 expression library by screening with polyclonal antibodies raised against a rat liver microsomal carboxylesterase. This clone of 1.8 kb contained an open reading frame encoding a mature protein of 531 amino acids with a predicted molecular weight of 58,084. The 5' portion of the clone coded for 9 amino acids of a putative signal peptide. The 3' end of the clone included an untranslated region and a poly (A) tail. Carboxylesterase active site regions, five potential N-linked glycosylation sites, and 2 postulated cystine disulfide bridges were found in the cDNA-deduced amino acid sequence. Sequences obtained from tryptic peptides and the NH2-terminus of the purified native carboxylesterase were aligned with the deduced amino acid sequence, and the overall identity was 84%. Southern blot analysis suggested the presence of multiple genes. Thus it is concluded that we have cloned a rat liver carboxylesterase, and that this enzyme is a member of a multigene family.
ESTHER : Long_1988_Biochem.Biophys.Res.Commun_156_866
PubMedSearch : Long_1988_Biochem.Biophys.Res.Commun_156_866
PubMedID: 2973315
Gene_locus related to this paper: ratno-Ces1c

Title : Human microsomal xenobiotic epoxide hydrolase. Complementary DNA sequence, complementary DNA-directed expression in COS-1 cells, and chromosomal localization - Skoda_1988_J.Biol.Chem_263_1549
Author(s) : Skoda RC , Demierre A , McBride OW , Gonzalez FJ , Meyer UA
Ref : Journal of Biological Chemistry , 263 :1549 , 1988
Abstract : A lambda gt11 expression library constructed from human liver mRNA was screened with an antibody against human microsomal xenobiotic epoxide hydrolase. The clone pheh32 contains an insert of 1742 base pairs with an open reading frame coding for a protein of 455 amino acids with a calculated Mr of 52,956. The nucleotide sequence is 77% similar to the previously reported rat xenobiotic epoxide hydrolase cDNA sequence. The deduced amino acid sequence of the human epoxide hydrolase is 80% similar to the previously reported rabbit and 84% similar to the deduced rat protein sequence. The NH2-terminal amino acids deduced from the human xenobiotic epoxide hydrolase cDNA are identical to the published 19 NH2-terminal amino acids of the purified human xenobiotic epoxide hydrolase protein. Northern blot analysis revealed a single mRNA band of 1.8 kilobases. Southern blot analysis indicated that there is only one gene copy/haploid genome. The human xenobiotic epoxide hydrolase gene was assigned to the long arm of human chromosome 1. Several restriction fragment length polymorphisms were observed with the human epoxide hydrolase cDNA. pheh32 was expressed as enzymatically active protein in cultured monkey kidney cells (COS-1).
ESTHER : Skoda_1988_J.Biol.Chem_263_1549
PubMedSearch : Skoda_1988_J.Biol.Chem_263_1549
PubMedID: 2891713
Gene_locus related to this paper: human-EPHX1