The Experts below are selected from a list of 1386 Experts worldwide ranked by ideXlab platform
Daniel Levy - One of the best experts on this subject based on the ideXlab platform.
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Transcription of the Human Microsomal Epoxide Hydrolase Gene (EPHX1) Is Regulated by PARP-1 and Histone H1.2. Association with Sodium-Dependent Bile Acid Transport.
PLOS ONE, 2015Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes. These compounds are involved in cholesterol homeostasis, lipid digestion, excretion of xenobiotics and the regulation of several nuclear receptors and signaling transduction pathways. Previous studies have demonstrated the critical role of GATA-4, a C/EBPα-NF/Y complex and an HNF-4α/CAR/RXR/PSF complex in the transcriptional regulation of the mEH gene (EPHX1). Studies also identified heterozygous mutations in human EPHX1 that resulted in a 95% decrease in mEH expression levels which was associated with a decrease in bile acid transport and severe hypercholanemia. In the present investigation we demonstrate that EPHX1 transcription is significantly inhibited by two heterozygous mutations observed in the Old Order Amish population that present numerous hypercholanemic subjects in the absence of liver damage suggesting a defect in bile acid transport into the hepatocyte. The identity of the regulatory proteins binding to these sites, established using biotinylated oligonucleotides in conjunction with mass spectrometry was shown to be poly(ADP-ribose)polymerase-1 (PARP-1) bound to the EPHX1 proximal promoter and a linker histone complex, H1.2/Aly, bound to a regulatory intron 1 site. These sites exhibited 71% homology and may represent potential nucleosome positioning domains. The high frequency of the H1.2 site polymorphism in the Amish population results in a potential genetic predisposition to hypercholanemia and in conjunction with our previous studies, further supports the critical role of mEH in mediating bile acid transport into hepatocytes.
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transcription of the human microsomal epoxide hydrolase gene EPHX1 is regulated by parp 1 and histone h1 2 association with sodium dependent bile acid transport
PLOS ONE, 2015Co-Authors: Hui Peng, Shuping Zhong, Daniel LevyAbstract:Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes. These compounds are involved in cholesterol homeostasis, lipid digestion, excretion of xenobiotics and the regulation of several nuclear receptors and signaling transduction pathways. Previous studies have demonstrated the critical role of GATA-4, a C/EBPα-NF/Y complex and an HNF-4α/CAR/RXR/PSF complex in the transcriptional regulation of the mEH gene (EPHX1). Studies also identified heterozygous mutations in human EPHX1 that resulted in a 95% decrease in mEH expression levels which was associated with a decrease in bile acid transport and severe hypercholanemia. In the present investigation we demonstrate that EPHX1 transcription is significantly inhibited by two heterozygous mutations observed in the Old Order Amish population that present numerous hypercholanemic subjects in the absence of liver damage suggesting a defect in bile acid transport into the hepatocyte. The identity of the regulatory proteins binding to these sites, established using biotinylated oligonucleotides in conjunction with mass spectrometry was shown to be poly(ADP-ribose)polymerase-1 (PARP-1) bound to the EPHX1 proximal promoter and a linker histone complex, H1.2/Aly, bound to a regulatory intron 1 site. These sites exhibited 71% homology and may represent potential nucleosome positioning domains. The high frequency of the H1.2 site polymorphism in the Amish population results in a potential genetic predisposition to hypercholanemia and in conjunction with our previous studies, further supports the critical role of mEH in mediating bile acid transport into hepatocytes.
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transcription of the human microsomal epoxide hydrolase gene EPHX1 is regulated by an hnf 4α car rxr psf complex
Biochimica et Biophysica Acta, 2013Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes where they are involved in cholesterol excretion and metabolism, lipid digestion and regulating numerous signaling pathways. Previous studies have demonstrated the critical role of GATA-4 and a C/EBPα–NF/Y complex in the regulation of the mEH gene (EPHX1). In this study we show that HNF-4α and CAR/RXR also bind to the proximal promoter region and regulate EPHX1 expression. Bile acids, which inhibit the expression of HNF-4α also decrease the expression of EPHX1. Studies also established that the binding of HNF-4α was essential for the activation of EPHX1 activity by CAR suggesting the formation of a complex between these adjacent factors. The nature of this regulatory complex was further explored using a biotinylated oligonucleotide of this region in conjunction with BioMag beads and mass spectrometric analysis which demonstrated the presence of an additional inhibitory factor (PSF), confirmed by co-immunoprecipitation and ChIP analyses, which interacted with DNA-bound CAR/RXR/HNF-4α forming a 4-component regulatory complex.
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Transcription of the human microsomal epoxide hydrolase gene (EPHX1) is regulated by an HNF-4α/CAR/RXR/PSF complex.
Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, 2013Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes where they are involved in cholesterol excretion and metabolism, lipid digestion and regulating numerous signaling pathways. Previous studies have demonstrated the critical role of GATA-4 and a C/EBPα–NF/Y complex in the regulation of the mEH gene (EPHX1). In this study we show that HNF-4α and CAR/RXR also bind to the proximal promoter region and regulate EPHX1 expression. Bile acids, which inhibit the expression of HNF-4α also decrease the expression of EPHX1. Studies also established that the binding of HNF-4α was essential for the activation of EPHX1 activity by CAR suggesting the formation of a complex between these adjacent factors. The nature of this regulatory complex was further explored using a biotinylated oligonucleotide of this region in conjunction with BioMag beads and mass spectrometric analysis which demonstrated the presence of an additional inhibitory factor (PSF), confirmed by co-immunoprecipitation and ChIP analyses, which interacted with DNA-bound CAR/RXR/HNF-4α forming a 4-component regulatory complex.
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ccaat enhancer binding protein α c ebpα activates transcription of the human microsomal epoxide hydrolase gene EPHX1 through the interaction with dna bound nf y
Journal of Biological Chemistry, 2004Co-Authors: Qin-shi Zhu, Bin Qian, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) plays a central role in xenobiotic metabolism as well as mediating the sodium-dependent uptake of bile acids into the liver, where these compounds regulate numerous biological processes such as cholesterol metabolism and hepatocyte signaling pathways. Little is known, however, about the factors that control the constitutive and inducible expression of the mEH gene (EPHX1) that is altered during development and in response to numerous xenobiotics. In previous studies we have established that GATA-4 binding to the EPHX1 core promoter is critical for EPHX1 expression. The –80/+25 bp core promoter also contained a reversed CCAAT box (–5/–1 bp), integrity of which was required for maximal basal EPHX1 transcription in HepG2 cells. Transient transfection of CCAAT/enhancer-binding protein α (C/EBPα) substantially stimulated EPHX1 promoter activity. Electrophoretic mobility shift assays, however, revealed that nuclear factor Y (NF-Y), but not C/EBPα, directly bound to this site although increased expression of NF-Y had no effect on EPHX1 promoter activity. These results suggested that C/EBPα activated EPHX1 expression through its interaction with NF-Y bound to the CCAAT box. The existence of a C/EBPα[NF-Y] complex was supported by electrophoretic mobility shift assays using antibodies against NF-Y and C/EBPα as well as by the ability of a dominant-negative NF-Y expression vector to inhibit promoter activity. The interaction between these transcription factors was established by co-immunoprecipitation analysis and glutathione S-transferase pull-down assays, whereas the association of the two factors and the interaction of NF-Y with the CCAAT box in vivo was confirmed by chromatin immunoprecipitation assays. C/EBPα-dependent EPHX1 activation was also supported by reconstitution studies in HeLa cells that lack this protein. These results establish that EPHX1 expression is regulated by C/EBPα interacting with DNA-bound NF-Y.
Hui Peng - One of the best experts on this subject based on the ideXlab platform.
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transcription of the human microsomal epoxide hydrolase gene EPHX1 is regulated by parp 1 and histone h1 2 association with sodium dependent bile acid transport
PLOS ONE, 2015Co-Authors: Hui Peng, Shuping Zhong, Daniel LevyAbstract:Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes. These compounds are involved in cholesterol homeostasis, lipid digestion, excretion of xenobiotics and the regulation of several nuclear receptors and signaling transduction pathways. Previous studies have demonstrated the critical role of GATA-4, a C/EBPα-NF/Y complex and an HNF-4α/CAR/RXR/PSF complex in the transcriptional regulation of the mEH gene (EPHX1). Studies also identified heterozygous mutations in human EPHX1 that resulted in a 95% decrease in mEH expression levels which was associated with a decrease in bile acid transport and severe hypercholanemia. In the present investigation we demonstrate that EPHX1 transcription is significantly inhibited by two heterozygous mutations observed in the Old Order Amish population that present numerous hypercholanemic subjects in the absence of liver damage suggesting a defect in bile acid transport into the hepatocyte. The identity of the regulatory proteins binding to these sites, established using biotinylated oligonucleotides in conjunction with mass spectrometry was shown to be poly(ADP-ribose)polymerase-1 (PARP-1) bound to the EPHX1 proximal promoter and a linker histone complex, H1.2/Aly, bound to a regulatory intron 1 site. These sites exhibited 71% homology and may represent potential nucleosome positioning domains. The high frequency of the H1.2 site polymorphism in the Amish population results in a potential genetic predisposition to hypercholanemia and in conjunction with our previous studies, further supports the critical role of mEH in mediating bile acid transport into hepatocytes.
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Transcription of the Human Microsomal Epoxide Hydrolase Gene (EPHX1) Is Regulated by PARP-1 and Histone H1.2. Association with Sodium-Dependent Bile Acid Transport.
PLOS ONE, 2015Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes. These compounds are involved in cholesterol homeostasis, lipid digestion, excretion of xenobiotics and the regulation of several nuclear receptors and signaling transduction pathways. Previous studies have demonstrated the critical role of GATA-4, a C/EBPα-NF/Y complex and an HNF-4α/CAR/RXR/PSF complex in the transcriptional regulation of the mEH gene (EPHX1). Studies also identified heterozygous mutations in human EPHX1 that resulted in a 95% decrease in mEH expression levels which was associated with a decrease in bile acid transport and severe hypercholanemia. In the present investigation we demonstrate that EPHX1 transcription is significantly inhibited by two heterozygous mutations observed in the Old Order Amish population that present numerous hypercholanemic subjects in the absence of liver damage suggesting a defect in bile acid transport into the hepatocyte. The identity of the regulatory proteins binding to these sites, established using biotinylated oligonucleotides in conjunction with mass spectrometry was shown to be poly(ADP-ribose)polymerase-1 (PARP-1) bound to the EPHX1 proximal promoter and a linker histone complex, H1.2/Aly, bound to a regulatory intron 1 site. These sites exhibited 71% homology and may represent potential nucleosome positioning domains. The high frequency of the H1.2 site polymorphism in the Amish population results in a potential genetic predisposition to hypercholanemia and in conjunction with our previous studies, further supports the critical role of mEH in mediating bile acid transport into hepatocytes.
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transcription of the human microsomal epoxide hydrolase gene EPHX1 is regulated by an hnf 4α car rxr psf complex
Biochimica et Biophysica Acta, 2013Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes where they are involved in cholesterol excretion and metabolism, lipid digestion and regulating numerous signaling pathways. Previous studies have demonstrated the critical role of GATA-4 and a C/EBPα–NF/Y complex in the regulation of the mEH gene (EPHX1). In this study we show that HNF-4α and CAR/RXR also bind to the proximal promoter region and regulate EPHX1 expression. Bile acids, which inhibit the expression of HNF-4α also decrease the expression of EPHX1. Studies also established that the binding of HNF-4α was essential for the activation of EPHX1 activity by CAR suggesting the formation of a complex between these adjacent factors. The nature of this regulatory complex was further explored using a biotinylated oligonucleotide of this region in conjunction with BioMag beads and mass spectrometric analysis which demonstrated the presence of an additional inhibitory factor (PSF), confirmed by co-immunoprecipitation and ChIP analyses, which interacted with DNA-bound CAR/RXR/HNF-4α forming a 4-component regulatory complex.
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Transcription of the human microsomal epoxide hydrolase gene (EPHX1) is regulated by an HNF-4α/CAR/RXR/PSF complex.
Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, 2013Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes where they are involved in cholesterol excretion and metabolism, lipid digestion and regulating numerous signaling pathways. Previous studies have demonstrated the critical role of GATA-4 and a C/EBPα–NF/Y complex in the regulation of the mEH gene (EPHX1). In this study we show that HNF-4α and CAR/RXR also bind to the proximal promoter region and regulate EPHX1 expression. Bile acids, which inhibit the expression of HNF-4α also decrease the expression of EPHX1. Studies also established that the binding of HNF-4α was essential for the activation of EPHX1 activity by CAR suggesting the formation of a complex between these adjacent factors. The nature of this regulatory complex was further explored using a biotinylated oligonucleotide of this region in conjunction with BioMag beads and mass spectrometric analysis which demonstrated the presence of an additional inhibitory factor (PSF), confirmed by co-immunoprecipitation and ChIP analyses, which interacted with DNA-bound CAR/RXR/HNF-4α forming a 4-component regulatory complex.
Qin-shi Zhu - One of the best experts on this subject based on the ideXlab platform.
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Transcription of the Human Microsomal Epoxide Hydrolase Gene (EPHX1) Is Regulated by PARP-1 and Histone H1.2. Association with Sodium-Dependent Bile Acid Transport.
PLOS ONE, 2015Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes. These compounds are involved in cholesterol homeostasis, lipid digestion, excretion of xenobiotics and the regulation of several nuclear receptors and signaling transduction pathways. Previous studies have demonstrated the critical role of GATA-4, a C/EBPα-NF/Y complex and an HNF-4α/CAR/RXR/PSF complex in the transcriptional regulation of the mEH gene (EPHX1). Studies also identified heterozygous mutations in human EPHX1 that resulted in a 95% decrease in mEH expression levels which was associated with a decrease in bile acid transport and severe hypercholanemia. In the present investigation we demonstrate that EPHX1 transcription is significantly inhibited by two heterozygous mutations observed in the Old Order Amish population that present numerous hypercholanemic subjects in the absence of liver damage suggesting a defect in bile acid transport into the hepatocyte. The identity of the regulatory proteins binding to these sites, established using biotinylated oligonucleotides in conjunction with mass spectrometry was shown to be poly(ADP-ribose)polymerase-1 (PARP-1) bound to the EPHX1 proximal promoter and a linker histone complex, H1.2/Aly, bound to a regulatory intron 1 site. These sites exhibited 71% homology and may represent potential nucleosome positioning domains. The high frequency of the H1.2 site polymorphism in the Amish population results in a potential genetic predisposition to hypercholanemia and in conjunction with our previous studies, further supports the critical role of mEH in mediating bile acid transport into hepatocytes.
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transcription of the human microsomal epoxide hydrolase gene EPHX1 is regulated by an hnf 4α car rxr psf complex
Biochimica et Biophysica Acta, 2013Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes where they are involved in cholesterol excretion and metabolism, lipid digestion and regulating numerous signaling pathways. Previous studies have demonstrated the critical role of GATA-4 and a C/EBPα–NF/Y complex in the regulation of the mEH gene (EPHX1). In this study we show that HNF-4α and CAR/RXR also bind to the proximal promoter region and regulate EPHX1 expression. Bile acids, which inhibit the expression of HNF-4α also decrease the expression of EPHX1. Studies also established that the binding of HNF-4α was essential for the activation of EPHX1 activity by CAR suggesting the formation of a complex between these adjacent factors. The nature of this regulatory complex was further explored using a biotinylated oligonucleotide of this region in conjunction with BioMag beads and mass spectrometric analysis which demonstrated the presence of an additional inhibitory factor (PSF), confirmed by co-immunoprecipitation and ChIP analyses, which interacted with DNA-bound CAR/RXR/HNF-4α forming a 4-component regulatory complex.
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Transcription of the human microsomal epoxide hydrolase gene (EPHX1) is regulated by an HNF-4α/CAR/RXR/PSF complex.
Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, 2013Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes where they are involved in cholesterol excretion and metabolism, lipid digestion and regulating numerous signaling pathways. Previous studies have demonstrated the critical role of GATA-4 and a C/EBPα–NF/Y complex in the regulation of the mEH gene (EPHX1). In this study we show that HNF-4α and CAR/RXR also bind to the proximal promoter region and regulate EPHX1 expression. Bile acids, which inhibit the expression of HNF-4α also decrease the expression of EPHX1. Studies also established that the binding of HNF-4α was essential for the activation of EPHX1 activity by CAR suggesting the formation of a complex between these adjacent factors. The nature of this regulatory complex was further explored using a biotinylated oligonucleotide of this region in conjunction with BioMag beads and mass spectrometric analysis which demonstrated the presence of an additional inhibitory factor (PSF), confirmed by co-immunoprecipitation and ChIP analyses, which interacted with DNA-bound CAR/RXR/HNF-4α forming a 4-component regulatory complex.
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ccaat enhancer binding protein α c ebpα activates transcription of the human microsomal epoxide hydrolase gene EPHX1 through the interaction with dna bound nf y
Journal of Biological Chemistry, 2004Co-Authors: Qin-shi Zhu, Bin Qian, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) plays a central role in xenobiotic metabolism as well as mediating the sodium-dependent uptake of bile acids into the liver, where these compounds regulate numerous biological processes such as cholesterol metabolism and hepatocyte signaling pathways. Little is known, however, about the factors that control the constitutive and inducible expression of the mEH gene (EPHX1) that is altered during development and in response to numerous xenobiotics. In previous studies we have established that GATA-4 binding to the EPHX1 core promoter is critical for EPHX1 expression. The –80/+25 bp core promoter also contained a reversed CCAAT box (–5/–1 bp), integrity of which was required for maximal basal EPHX1 transcription in HepG2 cells. Transient transfection of CCAAT/enhancer-binding protein α (C/EBPα) substantially stimulated EPHX1 promoter activity. Electrophoretic mobility shift assays, however, revealed that nuclear factor Y (NF-Y), but not C/EBPα, directly bound to this site although increased expression of NF-Y had no effect on EPHX1 promoter activity. These results suggested that C/EBPα activated EPHX1 expression through its interaction with NF-Y bound to the CCAAT box. The existence of a C/EBPα[NF-Y] complex was supported by electrophoretic mobility shift assays using antibodies against NF-Y and C/EBPα as well as by the ability of a dominant-negative NF-Y expression vector to inhibit promoter activity. The interaction between these transcription factors was established by co-immunoprecipitation analysis and glutathione S-transferase pull-down assays, whereas the association of the two factors and the interaction of NF-Y with the CCAAT box in vivo was confirmed by chromatin immunoprecipitation assays. C/EBPα-dependent EPHX1 activation was also supported by reconstitution studies in HeLa cells that lack this protein. These results establish that EPHX1 expression is regulated by C/EBPα interacting with DNA-bound NF-Y.
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CCAAT/Enhancer-binding Protein α (C/EBPα) Activates Transcription of the Human Microsomal Epoxide Hydrolase Gene (EPHX1) through the Interaction with DNA-bound NF-Y
Journal of Biological Chemistry, 2004Co-Authors: Qin-shi Zhu, Bin Qian, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) plays a central role in xenobiotic metabolism as well as mediating the sodium-dependent uptake of bile acids into the liver, where these compounds regulate numerous biological processes such as cholesterol metabolism and hepatocyte signaling pathways. Little is known, however, about the factors that control the constitutive and inducible expression of the mEH gene (EPHX1) that is altered during development and in response to numerous xenobiotics. In previous studies we have established that GATA-4 binding to the EPHX1 core promoter is critical for EPHX1 expression. The –80/+25 bp core promoter also contained a reversed CCAAT box (–5/–1 bp), integrity of which was required for maximal basal EPHX1 transcription in HepG2 cells. Transient transfection of CCAAT/enhancer-binding protein α (C/EBPα) substantially stimulated EPHX1 promoter activity. Electrophoretic mobility shift assays, however, revealed that nuclear factor Y (NF-Y), but not C/EBPα, directly bound to this site although increased expression of NF-Y had no effect on EPHX1 promoter activity. These results suggested that C/EBPα activated EPHX1 expression through its interaction with NF-Y bound to the CCAAT box. The existence of a C/EBPα[NF-Y] complex was supported by electrophoretic mobility shift assays using antibodies against NF-Y and C/EBPα as well as by the ability of a dominant-negative NF-Y expression vector to inhibit promoter activity. The interaction between these transcription factors was established by co-immunoprecipitation analysis and glutathione S-transferase pull-down assays, whereas the association of the two factors and the interaction of NF-Y with the CCAAT box in vivo was confirmed by chromatin immunoprecipitation assays. C/EBPα-dependent EPHX1 activation was also supported by reconstitution studies in HeLa cells that lack this protein. These results establish that EPHX1 expression is regulated by C/EBPα interacting with DNA-bound NF-Y.
Shuping Zhong - One of the best experts on this subject based on the ideXlab platform.
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transcription of the human microsomal epoxide hydrolase gene EPHX1 is regulated by parp 1 and histone h1 2 association with sodium dependent bile acid transport
PLOS ONE, 2015Co-Authors: Hui Peng, Shuping Zhong, Daniel LevyAbstract:Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes. These compounds are involved in cholesterol homeostasis, lipid digestion, excretion of xenobiotics and the regulation of several nuclear receptors and signaling transduction pathways. Previous studies have demonstrated the critical role of GATA-4, a C/EBPα-NF/Y complex and an HNF-4α/CAR/RXR/PSF complex in the transcriptional regulation of the mEH gene (EPHX1). Studies also identified heterozygous mutations in human EPHX1 that resulted in a 95% decrease in mEH expression levels which was associated with a decrease in bile acid transport and severe hypercholanemia. In the present investigation we demonstrate that EPHX1 transcription is significantly inhibited by two heterozygous mutations observed in the Old Order Amish population that present numerous hypercholanemic subjects in the absence of liver damage suggesting a defect in bile acid transport into the hepatocyte. The identity of the regulatory proteins binding to these sites, established using biotinylated oligonucleotides in conjunction with mass spectrometry was shown to be poly(ADP-ribose)polymerase-1 (PARP-1) bound to the EPHX1 proximal promoter and a linker histone complex, H1.2/Aly, bound to a regulatory intron 1 site. These sites exhibited 71% homology and may represent potential nucleosome positioning domains. The high frequency of the H1.2 site polymorphism in the Amish population results in a potential genetic predisposition to hypercholanemia and in conjunction with our previous studies, further supports the critical role of mEH in mediating bile acid transport into hepatocytes.
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Transcription of the Human Microsomal Epoxide Hydrolase Gene (EPHX1) Is Regulated by PARP-1 and Histone H1.2. Association with Sodium-Dependent Bile Acid Transport.
PLOS ONE, 2015Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes. These compounds are involved in cholesterol homeostasis, lipid digestion, excretion of xenobiotics and the regulation of several nuclear receptors and signaling transduction pathways. Previous studies have demonstrated the critical role of GATA-4, a C/EBPα-NF/Y complex and an HNF-4α/CAR/RXR/PSF complex in the transcriptional regulation of the mEH gene (EPHX1). Studies also identified heterozygous mutations in human EPHX1 that resulted in a 95% decrease in mEH expression levels which was associated with a decrease in bile acid transport and severe hypercholanemia. In the present investigation we demonstrate that EPHX1 transcription is significantly inhibited by two heterozygous mutations observed in the Old Order Amish population that present numerous hypercholanemic subjects in the absence of liver damage suggesting a defect in bile acid transport into the hepatocyte. The identity of the regulatory proteins binding to these sites, established using biotinylated oligonucleotides in conjunction with mass spectrometry was shown to be poly(ADP-ribose)polymerase-1 (PARP-1) bound to the EPHX1 proximal promoter and a linker histone complex, H1.2/Aly, bound to a regulatory intron 1 site. These sites exhibited 71% homology and may represent potential nucleosome positioning domains. The high frequency of the H1.2 site polymorphism in the Amish population results in a potential genetic predisposition to hypercholanemia and in conjunction with our previous studies, further supports the critical role of mEH in mediating bile acid transport into hepatocytes.
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transcription of the human microsomal epoxide hydrolase gene EPHX1 is regulated by an hnf 4α car rxr psf complex
Biochimica et Biophysica Acta, 2013Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes where they are involved in cholesterol excretion and metabolism, lipid digestion and regulating numerous signaling pathways. Previous studies have demonstrated the critical role of GATA-4 and a C/EBPα–NF/Y complex in the regulation of the mEH gene (EPHX1). In this study we show that HNF-4α and CAR/RXR also bind to the proximal promoter region and regulate EPHX1 expression. Bile acids, which inhibit the expression of HNF-4α also decrease the expression of EPHX1. Studies also established that the binding of HNF-4α was essential for the activation of EPHX1 activity by CAR suggesting the formation of a complex between these adjacent factors. The nature of this regulatory complex was further explored using a biotinylated oligonucleotide of this region in conjunction with BioMag beads and mass spectrometric analysis which demonstrated the presence of an additional inhibitory factor (PSF), confirmed by co-immunoprecipitation and ChIP analyses, which interacted with DNA-bound CAR/RXR/HNF-4α forming a 4-component regulatory complex.
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Transcription of the human microsomal epoxide hydrolase gene (EPHX1) is regulated by an HNF-4α/CAR/RXR/PSF complex.
Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, 2013Co-Authors: Hui Peng, Qin-shi Zhu, Shuping Zhong, Daniel LevyAbstract:Abstract Microsomal epoxide hydrolase (mEH) is a bifunctional protein that plays a central role in the metabolism of numerous xenobiotics as well as mediating the sodium-dependent transport of bile acids into hepatocytes where they are involved in cholesterol excretion and metabolism, lipid digestion and regulating numerous signaling pathways. Previous studies have demonstrated the critical role of GATA-4 and a C/EBPα–NF/Y complex in the regulation of the mEH gene (EPHX1). In this study we show that HNF-4α and CAR/RXR also bind to the proximal promoter region and regulate EPHX1 expression. Bile acids, which inhibit the expression of HNF-4α also decrease the expression of EPHX1. Studies also established that the binding of HNF-4α was essential for the activation of EPHX1 activity by CAR suggesting the formation of a complex between these adjacent factors. The nature of this regulatory complex was further explored using a biotinylated oligonucleotide of this region in conjunction with BioMag beads and mass spectrometric analysis which demonstrated the presence of an additional inhibitory factor (PSF), confirmed by co-immunoprecipitation and ChIP analyses, which interacted with DNA-bound CAR/RXR/HNF-4α forming a 4-component regulatory complex.
Arnd Heuser - One of the best experts on this subject based on the ideXlab platform.
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soluble epoxide hydrolase is a susceptibility factor for heart failure in a rat model of human disease
Nature Genetics, 2008Co-Authors: Jan Monti, Judith Fischer, Svetlana Paskas, Matthias Heinig, Herbert Schulz, Claudia Gosele, Arnd HeuserAbstract:We aimed to identify genetic variants associated with heart failure by using a rat model of the human disease. We performed invasive cardiac hemodynamic measurements in F2 crosses between spontaneously hypertensive heart failure (SHHF) rats and reference strains. We combined linkage analyses with genome-wide expression profiling and identified Ephx2 as a heart failure susceptibility gene in SHHF rats. Specifically, we found that cis variation at Ephx2 segregated with heart failure and with increased transcript expression, protein expression and enzyme activity, leading to a more rapid hydrolysis of cardioprotective epoxyeicosatrienoic acids. To confirm our results, we tested the role of Ephx2 in heart failure using knockout mice. Ephx2 gene ablation protected from pressure overload-induced heart failure and cardiac arrhythmias. We further demonstrated differential regulation of EPHX2 in human heart failure, suggesting a cross-species role for Ephx2 in this complex disease.