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Akira Hara - One of the best experts on this subject based on the ideXlab platform.
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Inhibitors of human 20α-Hydroxysteroid dehydrogenase (AKR1C1).
The Journal of steroid biochemistry and molecular biology, 2010Co-Authors: Ossama El-kabbani, Urmi Dhagat, Akira HaraAbstract:Human 20α-Hydroxysteroid dehydrogenase (AKR1C1), a member of the aldo-keto reductase (AKR) superfamily, is one of four isoforms (with >84% amino acid sequence identity) existing in human tissues. AKR1C1 most efficiently reduces biologically active progesterone and 5α-pregnan-3α-ol-20-one into their corresponding 20α-Hydroxysteroids among the isoforms. The enzyme also accepts endogenous and xenobiotic non-steroidal carbonyl compounds as the substrates. In addition to the up-regulation of the AKR1C1 gene in cancer cells, the enzyme's over-expression in the cells of lung, ovary, uterine cervix, skin and colon carcinomas was reported to be associated with resistance against several anticancer agents. Thus, AKR1C1 may be a marker of the above cancers and a target of poor prognosis in cancer therapy. The recently determined X-ray crystal structures of AKR1C1/NADP(+)/20α-hydroxyprogesterone and AKR1C1/NADP(+)/3,5-dichlorosalicylic acid ternary complexes have provided a strong foundation for structure-based design methods to improve inhibitor selectivity and potency. In this review we provide an overview of the different types of AKR1C1 inhibitors and an update on the design of potent and selective inhibitors based on the crystal structure of the enzyme-inhibitor complex. Article from the Special issue on Targeted Inhibitors.
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factorizing the role of a critical leucine residue in the binding of substrate to human 20α Hydroxysteroid dehydrogenase akr1c1 molecular modeling and kinetic studies of the leu308val mutant enzyme
Bioorganic & Medicinal Chemistry Letters, 2010Co-Authors: Urmi Dhagat, Midori Soda, Akira Hara, Satoshi Endo, Ossama ElkabbaniAbstract:Abstract A comparison of the structures and kinetic properties of human 20α-Hydroxysteroid dehydrogenase (AKR1C1) and its mutant enzymes (Leu308Val and Leu308Ala) indicates that Leu308 is a selectivity determinant for substrate binding. While the Leu308Val mutation improved the catalytic efficiency ( k cat / K m ) of AKR1C1 towards the two substrates 5α-pregnane-3α,20α-diol (PregA) and 5β-pregnan-3α-ol-20-one (PregB), the Leu308Ala mutation rendered the enzyme inactive. In the docked model of PregA the conformation of the steroid molecule was similar to that of 20α-hydroxyprogesterone in the crystal structure of the AKR1C1 complex where the steroid did not interact with the catalytic residues Tyr55 and His117. In the case of PregB the steroid interacted with the catalytic residue His117 and formed close contacts with Leu308, suggesting that the binding mechanism of 3α-Hydroxysteroids in the active site of AKR1C1 is different from that of 20α-Hydroxysteroids.
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Factorizing the role of a critical leucine residue in the binding of substrate to human 20α-Hydroxysteroid dehydrogenase (AKR1C1): Molecular modeling and kinetic studies of the Leu308Val mutant enzyme
Bioorganic & medicinal chemistry letters, 2010Co-Authors: Urmi Dhagat, Midori Soda, Akira Hara, Satoshi Endo, Ossama El-kabbaniAbstract:A comparison of the structures and kinetic properties of human 20alpha-Hydroxysteroid dehydrogenase (AKR1C1) and its mutant enzymes (Leu308Val and Leu308Ala) indicates that Leu308 is a selectivity determinant for substrate binding. While the Leu308Val mutation improved the catalytic efficiency (k(cat)/K(m)) of AKR1C1 towards the two substrates 5alpha-pregnane-3alpha,20alpha-diol (PregA) and 5beta-pregnan-3alpha-ol-20-one (PregB), the Leu308Ala mutation rendered the enzyme inactive. In the docked model of PregA the conformation of the steroid molecule was similar to that of 20alpha-hydroxyprogesterone in the crystal structure of the AKR1C1 complex where the steroid did not interact with the catalytic residues Tyr55 and His117. In the case of PregB the steroid interacted with the catalytic residue His117 and formed close contacts with Leu308, suggesting that the binding mechanism of 3alpha-Hydroxysteroids in the active site of AKR1C1 is different from that of 20alpha-Hydroxysteroids.
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Rat NAD+-dependent 3α-Hydroxysteroid dehydrogenase (AKR1C17): A member of the aldo-keto reductase family highly expressed in kidney cytosol
Archives of Biochemistry and Biophysics, 2007Co-Authors: Masaharu Sanai, Ossama El-kabbani, Shuhei Ishikura, Kazuo Tajima, Satoshi Endo, Toshiyuki Matsunaga, Akira HaraAbstract:Abstract Mammalian 3α-Hydroxysteroid dehydrogenases (3α-HSDs) have been divided into two types: Cytosolic NADP(H)-dependent 3α-HSDs belonging to the aldo-keto reductase family, and mitochondrial and microsomal NAD + -dependent 3α-HSDs belonging to the short-chain dehydrogenase/reductase family. In this study, we characterized a rat aldo-keto reductase (AKR1C17), whose functions are unknown. The recombinant AKR1C17 efficiently oxidized 3α-Hydroxysteroids and bile acids using NAD + as the preferred coenzyme at an optimal pH of 7.4–9.5, and was inhibited by ketamine and organic anions. The mRNA for AKR1C17 was detected specifically in rat kidney, where the enzyme was more highly expressed as a cytosolic protein than NADP(H)-dependent 3α-HSD (AKR1C9). Thus, AKR1C17 represents a novel NAD + -dependent type of cytosolic 3α-HSD with unique inhibitor sensitivity and tissue distribution. In addition, the replacement of Gln270 and Glu276 of AKR1C17 with the corresponding residues of NADP(H)-dependent 3α-HSD resulted in a switch in favor of NADP + specificity, suggesting their key roles in coenzyme specificity.
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Molecular Cloning of a Novel Type of Rat Cytoplasmic 17b-Hydroxysteroid Dehydrogenase Distinct from the Type 5 Isozyme
2006Co-Authors: Shuhei Ishikura, Ossama El-kabbani, Masaharu Sanai, Kazuo Tajima, Toshiyuki Matsunaga, Kengo Matsumoto, Kenji Horie, Akira HaraAbstract:Rat liver contains two cytosolic enzymes (TBER1 and TBER2) that reduce 6-tert-butyl-2,3-epoxy-5-cyclohexene-1,4-dione into its 4R- and 4S-hydroxymetabolites. In this study, we cloned the cDNA for TBER1 and examined endogenous substrates using the homo-genous recombinant enzyme. The cDNA encoded a protein composed of 323 amino acids belongingtothealdo-ketoreductase family.TherecombinantTBER1efficientlyoxidized 17b-Hydroxysteroids and xenobiotic alicyclic alcohols usingNAD+ as the preferred coen-zyme at pH 7.4, and showed low activity towards 20a- and 3a-Hydroxysteroids, and 9-hydroxyprostaglandins. The enzyme was potently inhibited by diethylstilbestrol, hexestrol and zearalenone. The coenzyme specificity, broad substrate specificity and inhibitor sensitivity of the enzyme differed from those of rat NADPH-dependent 17b-Hydroxysteroid dehydrogenase type 5, which was cloned from the liver and charac-terized using the recombinant enzyme. The mRNA for TBER1 was highly expressed in rat liver, gastrointestinal tract and ovary, in contrast to specific expression of 17b-Hydroxysteroiddehydrogenase type5mRNAin the liverandkidney.Thus,TBER1repre-sentsanovel typeof17b-Hydroxysteroiddehydrogenasewithuniquecatalyticproperties and tissue distribution. In addition, TBER2 was identified as 3a-Hydroxysteroid dehydrogenase on chromatographic analysis of the enzyme activities in rat liver cytosol and characterization of the recombinant 3a-Hydroxysteroid dehydrogenase. Key words: aldo-keto reductase family, 9-hydroxyprostaglandin, 3a-Hydroxysteroid dehydrogenase, 17b-Hydroxysteroid dehydrogenase, 20a-Hydroxysteroid dehydrogen
Charles N Falany - One of the best experts on this subject based on the ideXlab platform.
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expression and characterization of the human 3β Hydroxysteroid sulfotransferases sult2b1a and sult2b1b
The Journal of Steroid Biochemistry and Molecular Biology, 2001Co-Authors: Connie A Meloche, Charles N FalanyAbstract:The human Hydroxysteroid sulfotransferase, dehydroepiandrosterone sulfotransferase (DHEA-ST), is highly expressed in liver and adrenal cortex and displays reactivity towards a broad range of Hydroxysteroids including 3β-Hydroxysteroids, 3α-Hydroxysteroids, estrogens with a 3-phenolic moiety, and 17-hydroxyl group of androgens. In contrast, characterization of the newly described human Hydroxysteroid sulfotransferase SULT2B1 isoforms shows that these enzymes are selective for the sulfation of 3β-Hydroxysteroids, such as pregnenolone, epiandrosterone, DHEA, and androstenediol. There was no activity detected towards testosterone, dexamethasone, β-estradiol, androsterone, or p-nitrophenol. The SULT2B1 gene encodes two isoforms, SULT2B1a and SULT2B1b, which are generated by alternate splicing of the first exon; therefore the SULT2B1 isoforms differ at their N-terminals. Northern Blot analysis detected a SULT2B1 message in RNA isolated from the human prostate and placenta. No SULT2B1 message was observed in RNA isolated from human liver, colon, lung, kidney, brain, or testis tissue. Purified SULT2B1a was used to generate a specific rabbit polyclonal anti-SULT2B1 antibody. The anti-SULT2B1 antibody did not react with expressed human EST, P-PST-1, M-PST, DHEA-ST, or ST1B2, during immunoblot analysis. The substrate specificity of the expressed SULT2B1 isoforms suggests that these enzymes are capable of regulating the activity of adrenal androgens in human tissues via their inactivation by sulfation.
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Expression and characterization of the human 3 beta-Hydroxysteroid sulfotransferases (SULT2B1a and SULT2B1b).
The Journal of steroid biochemistry and molecular biology, 2001Co-Authors: Connie A Meloche, Charles N FalanyAbstract:The human Hydroxysteroid sulfotransferase, dehydroepiandrosterone sulfotransferase (DHEA-ST), is highly expressed in liver and adrenal cortex and displays reactivity towards a broad range of Hydroxysteroids including 3 beta-Hydroxysteroids, 3 alpha-Hydroxysteroids, estrogens with a 3-phenolic moiety, and 17-hydroxyl group of androgens. In contrast, characterization of the newly described human Hydroxysteroid sulfotransferase SULT2B1 isoforms shows that these enzymes are selective for the sulfation of 3 beta-Hydroxysteroids, such as pregnenolone, epiandrosterone, DHEA, and androstenediol. There was no activity detected towards testosterone, dexamethasone, beta-estradiol, androsterone, or p-nitrophenol. The SULT2B1 gene encodes two isoforms, SULT2B1a and SULT2B1b, which are generated by alternate splicing of the first exon; therefore the SULT2B1 isoforms differ at their N-terminals. Northern Blot analysis detected a SULT2B1 message in RNA isolated from the human prostate and placenta. No SULT2B1 message was observed in RNA isolated from human liver, colon, lung, kidney, brain, or testis tissue. Purified SULT2B1a was used to generate a specific rabbit polyclonal anti-SULT2B1 antibody. The anti-SULT2B1 antibody did not react with expressed human EST, P-PST-1, M-PST, DHEA-ST, or ST1B2, during immunoblot analysis. The substrate specificity of the expressed SULT2B1 isoforms suggests that these enzymes are capable of regulating the activity of adrenal androgens in human tissues via their inactivation by sulfation.
Guangping Chen - One of the best experts on this subject based on the ideXlab platform.
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liver x receptor alpha mediated genistein induction of human dehydroepiandrosterone sulfotransferase hsult2a1 in hep g2 cells
Toxicology and Applied Pharmacology, 2013Co-Authors: Yue Chen, Chaoqun Huang, Tianyan Zhou, Shunfen Zhang, Alicia Mclaughlin, Guangping ChenAbstract:Cytosolic sulfotransferases are one of the major families of phase II drug metabolizing enzymes. Sulfotransferase-catalyzed sulfonation regulates hormone activities, metabolizes drugs, detoxifies xenobiotics, and bioactivates carcinogens. Human dehydroepiandrosterone sulfotransferase (hSULT2A1) plays important biological roles by sulfating endogenous Hydroxysteroids and exogenous xenobiotics. Genistein, mainly existing in soy food products, is a naturally occurring phytoestrogen with both chemopreventive and chemotherapeutic potential. Our previous studies have shown that genistein significantly induces hSULT2A1 in Hep G2 and Caco-2 cells. In this study, we investigated the roles of liver X receptor (LXRα) in the genistein induction of hSULT2A1. LXRs have been shown to induce expression of mouse Sult2a9 and hSULT2A1 gene. Our results demonstrate that LXRα mediates the genistein induction of hSULT2A1, supported by Western blot analysis results, hSULT2A1 promoter driven luciferase reporter gene assay results, and mRNA interference results. Chromatin immunoprecipitation (ChIP) assay results demonstrate that genistein increase the recruitment of hLXRα binding to the hSULT2A1 promoter. These results suggest that hLXRα plays an important role in the hSULT2A1 gene regulation. The biological functions of phytoestrogens may partially relate to their induction activity toward Hydroxysteroid SULT.
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estrogen related receptor errα mediated downregulation of human Hydroxysteroid sulfotransferase sult2a1 in hep g2 cells
Chemico-Biological Interactions, 2011Co-Authors: Chaoqun Huang, Yue Chen, Tianyan Zhou, Teng Sun, Shufen Zhang, Guangping ChenAbstract:Hydroxysteroid sulfotransferase SULT2A1 catalyzes the sulfation of Hydroxysteroids and xenobiotics. It plays an important role in the detoxification of hydroxyl-containing xenobiotics and in the regulation of the biological activities of Hydroxysteroids. ERRα is an orphan member of the nuclear receptor superfamily that is closely related to estrogen receptor alpha (ERα). Here we report that the mRNA expression of human SULT2A1 was suppressed by ERRα in Hep G2 cells. To investigate the mechanisms of this regulation, the effects of ERRα on human SULT2A1 promoter transcription in Hep G2 cells were investigated. Reporter luciferase assay results showed that ERRα significantly represses human SULT2A1 promoter transcription in Hep G2 cells. Deletion analysis indicated that human SULT2A1 promoter region between positions -188 and -130 is necessary for its repression by ERRα in Hep G2 cells. The 5' DNA -188 to -130 region of human SULT2A1 contains IR2 and DR4 hormone response elements and two putative ERRα response elements (ERREs) (ERRE188: GCAAGCTCA and ERRE155: ATAAGTTCA). Interestingly, ERRE188 overlaps with the IR2 element and ERRE155 overlaps with the DR4 element. Our further investigation demonstrated that ERRα represses human SULT2A1 promoter transcription by competing with other nuclear receptors for binding to IR2 or DR4 elements. The interaction of ERRE188 and ERRE155 elements with ERRα was confirmed by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) analysis. Our results suggest that ERRα may play an important role in regulating the metabolism of drugs and xenobiotics and in regulating endogenous Hydroxysteroid activities via the regulation of SULT2A1.
Ossama El-kabbani - One of the best experts on this subject based on the ideXlab platform.
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Inhibitors of human 20α-Hydroxysteroid dehydrogenase (AKR1C1).
The Journal of steroid biochemistry and molecular biology, 2010Co-Authors: Ossama El-kabbani, Urmi Dhagat, Akira HaraAbstract:Human 20α-Hydroxysteroid dehydrogenase (AKR1C1), a member of the aldo-keto reductase (AKR) superfamily, is one of four isoforms (with >84% amino acid sequence identity) existing in human tissues. AKR1C1 most efficiently reduces biologically active progesterone and 5α-pregnan-3α-ol-20-one into their corresponding 20α-Hydroxysteroids among the isoforms. The enzyme also accepts endogenous and xenobiotic non-steroidal carbonyl compounds as the substrates. In addition to the up-regulation of the AKR1C1 gene in cancer cells, the enzyme's over-expression in the cells of lung, ovary, uterine cervix, skin and colon carcinomas was reported to be associated with resistance against several anticancer agents. Thus, AKR1C1 may be a marker of the above cancers and a target of poor prognosis in cancer therapy. The recently determined X-ray crystal structures of AKR1C1/NADP(+)/20α-hydroxyprogesterone and AKR1C1/NADP(+)/3,5-dichlorosalicylic acid ternary complexes have provided a strong foundation for structure-based design methods to improve inhibitor selectivity and potency. In this review we provide an overview of the different types of AKR1C1 inhibitors and an update on the design of potent and selective inhibitors based on the crystal structure of the enzyme-inhibitor complex. Article from the Special issue on Targeted Inhibitors.
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Factorizing the role of a critical leucine residue in the binding of substrate to human 20α-Hydroxysteroid dehydrogenase (AKR1C1): Molecular modeling and kinetic studies of the Leu308Val mutant enzyme
Bioorganic & medicinal chemistry letters, 2010Co-Authors: Urmi Dhagat, Midori Soda, Akira Hara, Satoshi Endo, Ossama El-kabbaniAbstract:A comparison of the structures and kinetic properties of human 20alpha-Hydroxysteroid dehydrogenase (AKR1C1) and its mutant enzymes (Leu308Val and Leu308Ala) indicates that Leu308 is a selectivity determinant for substrate binding. While the Leu308Val mutation improved the catalytic efficiency (k(cat)/K(m)) of AKR1C1 towards the two substrates 5alpha-pregnane-3alpha,20alpha-diol (PregA) and 5beta-pregnan-3alpha-ol-20-one (PregB), the Leu308Ala mutation rendered the enzyme inactive. In the docked model of PregA the conformation of the steroid molecule was similar to that of 20alpha-hydroxyprogesterone in the crystal structure of the AKR1C1 complex where the steroid did not interact with the catalytic residues Tyr55 and His117. In the case of PregB the steroid interacted with the catalytic residue His117 and formed close contacts with Leu308, suggesting that the binding mechanism of 3alpha-Hydroxysteroids in the active site of AKR1C1 is different from that of 20alpha-Hydroxysteroids.
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Rat NAD+-dependent 3α-Hydroxysteroid dehydrogenase (AKR1C17): A member of the aldo-keto reductase family highly expressed in kidney cytosol
Archives of Biochemistry and Biophysics, 2007Co-Authors: Masaharu Sanai, Ossama El-kabbani, Shuhei Ishikura, Kazuo Tajima, Satoshi Endo, Toshiyuki Matsunaga, Akira HaraAbstract:Abstract Mammalian 3α-Hydroxysteroid dehydrogenases (3α-HSDs) have been divided into two types: Cytosolic NADP(H)-dependent 3α-HSDs belonging to the aldo-keto reductase family, and mitochondrial and microsomal NAD + -dependent 3α-HSDs belonging to the short-chain dehydrogenase/reductase family. In this study, we characterized a rat aldo-keto reductase (AKR1C17), whose functions are unknown. The recombinant AKR1C17 efficiently oxidized 3α-Hydroxysteroids and bile acids using NAD + as the preferred coenzyme at an optimal pH of 7.4–9.5, and was inhibited by ketamine and organic anions. The mRNA for AKR1C17 was detected specifically in rat kidney, where the enzyme was more highly expressed as a cytosolic protein than NADP(H)-dependent 3α-HSD (AKR1C9). Thus, AKR1C17 represents a novel NAD + -dependent type of cytosolic 3α-HSD with unique inhibitor sensitivity and tissue distribution. In addition, the replacement of Gln270 and Glu276 of AKR1C17 with the corresponding residues of NADP(H)-dependent 3α-HSD resulted in a switch in favor of NADP + specificity, suggesting their key roles in coenzyme specificity.
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Molecular Cloning of a Novel Type of Rat Cytoplasmic 17b-Hydroxysteroid Dehydrogenase Distinct from the Type 5 Isozyme
2006Co-Authors: Shuhei Ishikura, Ossama El-kabbani, Masaharu Sanai, Kazuo Tajima, Toshiyuki Matsunaga, Kengo Matsumoto, Kenji Horie, Akira HaraAbstract:Rat liver contains two cytosolic enzymes (TBER1 and TBER2) that reduce 6-tert-butyl-2,3-epoxy-5-cyclohexene-1,4-dione into its 4R- and 4S-hydroxymetabolites. In this study, we cloned the cDNA for TBER1 and examined endogenous substrates using the homo-genous recombinant enzyme. The cDNA encoded a protein composed of 323 amino acids belongingtothealdo-ketoreductase family.TherecombinantTBER1efficientlyoxidized 17b-Hydroxysteroids and xenobiotic alicyclic alcohols usingNAD+ as the preferred coen-zyme at pH 7.4, and showed low activity towards 20a- and 3a-Hydroxysteroids, and 9-hydroxyprostaglandins. The enzyme was potently inhibited by diethylstilbestrol, hexestrol and zearalenone. The coenzyme specificity, broad substrate specificity and inhibitor sensitivity of the enzyme differed from those of rat NADPH-dependent 17b-Hydroxysteroid dehydrogenase type 5, which was cloned from the liver and charac-terized using the recombinant enzyme. The mRNA for TBER1 was highly expressed in rat liver, gastrointestinal tract and ovary, in contrast to specific expression of 17b-Hydroxysteroiddehydrogenase type5mRNAin the liverandkidney.Thus,TBER1repre-sentsanovel typeof17b-Hydroxysteroiddehydrogenasewithuniquecatalyticproperties and tissue distribution. In addition, TBER2 was identified as 3a-Hydroxysteroid dehydrogenase on chromatographic analysis of the enzyme activities in rat liver cytosol and characterization of the recombinant 3a-Hydroxysteroid dehydrogenase. Key words: aldo-keto reductase family, 9-hydroxyprostaglandin, 3a-Hydroxysteroid dehydrogenase, 17b-Hydroxysteroid dehydrogenase, 20a-Hydroxysteroid dehydrogen
Connie A Meloche - One of the best experts on this subject based on the ideXlab platform.
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expression and characterization of the human 3β Hydroxysteroid sulfotransferases sult2b1a and sult2b1b
The Journal of Steroid Biochemistry and Molecular Biology, 2001Co-Authors: Connie A Meloche, Charles N FalanyAbstract:The human Hydroxysteroid sulfotransferase, dehydroepiandrosterone sulfotransferase (DHEA-ST), is highly expressed in liver and adrenal cortex and displays reactivity towards a broad range of Hydroxysteroids including 3β-Hydroxysteroids, 3α-Hydroxysteroids, estrogens with a 3-phenolic moiety, and 17-hydroxyl group of androgens. In contrast, characterization of the newly described human Hydroxysteroid sulfotransferase SULT2B1 isoforms shows that these enzymes are selective for the sulfation of 3β-Hydroxysteroids, such as pregnenolone, epiandrosterone, DHEA, and androstenediol. There was no activity detected towards testosterone, dexamethasone, β-estradiol, androsterone, or p-nitrophenol. The SULT2B1 gene encodes two isoforms, SULT2B1a and SULT2B1b, which are generated by alternate splicing of the first exon; therefore the SULT2B1 isoforms differ at their N-terminals. Northern Blot analysis detected a SULT2B1 message in RNA isolated from the human prostate and placenta. No SULT2B1 message was observed in RNA isolated from human liver, colon, lung, kidney, brain, or testis tissue. Purified SULT2B1a was used to generate a specific rabbit polyclonal anti-SULT2B1 antibody. The anti-SULT2B1 antibody did not react with expressed human EST, P-PST-1, M-PST, DHEA-ST, or ST1B2, during immunoblot analysis. The substrate specificity of the expressed SULT2B1 isoforms suggests that these enzymes are capable of regulating the activity of adrenal androgens in human tissues via their inactivation by sulfation.
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Expression and characterization of the human 3 beta-Hydroxysteroid sulfotransferases (SULT2B1a and SULT2B1b).
The Journal of steroid biochemistry and molecular biology, 2001Co-Authors: Connie A Meloche, Charles N FalanyAbstract:The human Hydroxysteroid sulfotransferase, dehydroepiandrosterone sulfotransferase (DHEA-ST), is highly expressed in liver and adrenal cortex and displays reactivity towards a broad range of Hydroxysteroids including 3 beta-Hydroxysteroids, 3 alpha-Hydroxysteroids, estrogens with a 3-phenolic moiety, and 17-hydroxyl group of androgens. In contrast, characterization of the newly described human Hydroxysteroid sulfotransferase SULT2B1 isoforms shows that these enzymes are selective for the sulfation of 3 beta-Hydroxysteroids, such as pregnenolone, epiandrosterone, DHEA, and androstenediol. There was no activity detected towards testosterone, dexamethasone, beta-estradiol, androsterone, or p-nitrophenol. The SULT2B1 gene encodes two isoforms, SULT2B1a and SULT2B1b, which are generated by alternate splicing of the first exon; therefore the SULT2B1 isoforms differ at their N-terminals. Northern Blot analysis detected a SULT2B1 message in RNA isolated from the human prostate and placenta. No SULT2B1 message was observed in RNA isolated from human liver, colon, lung, kidney, brain, or testis tissue. Purified SULT2B1a was used to generate a specific rabbit polyclonal anti-SULT2B1 antibody. The anti-SULT2B1 antibody did not react with expressed human EST, P-PST-1, M-PST, DHEA-ST, or ST1B2, during immunoblot analysis. The substrate specificity of the expressed SULT2B1 isoforms suggests that these enzymes are capable of regulating the activity of adrenal androgens in human tissues via their inactivation by sulfation.
