Short-term efficacy and safety of edoxaban for venous thromboembolism after total hip or knee arthroplasty: a systematic review and meta-analysis.

OBJECTIVE: Previous preliminary clinical trials have confirmed that edoxaban can be efficacious for venous thromboembolism (VTE). This meta-analysis was considered to evaluate edoxaban's short-term efficacy and safety for venous thromboembolism after arthroplasty. MATERIALS AND METHODS: A comprehensive search was performed in these databases: PubMed, MEDLINE, Web of Science, and EMBASE on March 2022. All eligible trials should be randomized controlled trials (RCTs) when evaluating short-term efficacy and safety outcomes of edoxaban for VTE after total hip or knee arthroplasty. RESULTS: Nine RCTs with 4274 patients were involved in this meta-analysis. Edoxaban in the VTE group prevented the incidence of VTE and indicated valuable clinical efficacy. The incidence of adverse events (AEs) and adverse drug reactions (ADRs) in the edoxaban group was decreased than that in other groups. Edoxaban increased the incidence of all bleeding events. However, in the edoxaban group and other groups, there was no statistical difference between major bleeding events and clinically relevant non-major or minor bleeding events. Edoxaban subgroups included edoxaban 15 mg, edoxaban 30 mg and edoxaban 60 mg prevented the incidence of VTE. Edoxaban 30 mg and 60 mg group increased the risk of all bleeding events. Edoxaban 30 mg can increase the incidence of major bleeding events. There was no difference in clinically relevant non-major or minor bleeding events. Edoxaban 30 mg can decrease the incidence of AEs. CONCLUSIONS: Edoxaban was an efficacious and safe option to prevent and treat VTE in patients undergoing arthroplasty. However, we need further trials to explore edoxaban's long-term efficacy and safety.

Molecular cloning, expression, and characterization of the Drosophila 85-kilodalton TFIID subunit.

Transcription initiation factor TFIID is a multimeric protein complex that plays a central role in mediating promoter responses to various activators and repressors. To further understand the role of the 85-kDa TFIID subunit (p85), we have cloned the corresponding cDNA with a probe based on an amino acid sequence of the purified protein. The recombinant p85 interacts directly with both the TATA box-binding subunit (TFIID tau or TBP) and the 110-kDa subunit (p110) of TFIID, suggesting that p85 may play a role in helping to anchor p110 within the TFIID complex and, with other studies, that TFIID assembly and function may involve a concerted series of subunit interactions. Interestingly, the carboxy terminus of p85 contains eight of the WD-40 repeats found originally in the beta subunit of G proteins and more recently in other transcriptional regulatory factors. However, truncated p85 lacking all the WD-40 repeats maintained interactions with both TFIID tau and p110. These observations leave open the possibility of a distinct function for the WD-40 repeats, possibly in transducing signals by interactions with transcriptional regulators and/or other components of the basic transcriptional machinery.

Characterization and expression of hepatic sulfotransferase involved in the metabolism of N-substituted aryl compounds.

An aryl sulfotransferase, whose cDNA was isolated from the rat liver library, was found to catalyze bioactivation of minoxidil through N-O-sulfation and N-sulfation of a carcinogenic heterocyclic amine, IQ, by expression in COS-1 cells. cDNA of a human ortholog also was isolated and characterized as a major minoxidil-activating enzyme in human liver. Another group of aryl sulfotransferases catalyzing O-sulfation of carcinogenic N-hydroxyarylamines was separated from livers of rats and humans. These sulfotransferases have been shown to possess similar functional properties and also to relate immunochemically with each other. Current understanding on the primary structure of these sulfotransferases also is discussed.

Purification of hepatic N-hydroxyarylamine sulfotransferases and their regulation by growth hormone and thyroid hormone in rats.

From liver cytosols of male Sprague-Dawley rats, two N-hydroxyarylamine sulfotransferases (HASTs) which sulfate N-hydroxy-2-acetylaminofluorene and a phenolsulfotransferase (PST-I) have been purified about 290-, 690-, and 210-fold, respectively, by the use of DEAE-anion exchange, Blue-Sepharose CL-6B, DEAE-HPLC, and ATP-agarose affinity chromatography. All three enzymes showed almost the same molecular weight of 33 kDa on SDS-polyacrylamide gel electrophoresis. In Western blots using antibody raised against HAST I, the two HASTs, but not PST-I, were detected. The content of total HAST in male rats was estimated as 4-5 micrograms/mg cytosolic protein, about 4 times higher than that in female rats. Direct comparison of the DEAE-HPLC elution profiles of cytosol showed that HAST I and HAST II were male-dominant and male-specific, respectively, in their expression in the livers. Hypophysectomy decreased the level of HAST by 60% in male rats, but had no obvious effect in female rats. Intermittent injection of growth hormone to mimic the male secretory pattern raised the content in hypophysectomized rats of both sexes close to that in intact male rats, while the continuous infusion of growth hormone to mimic the female secretory pattern showed limited effects. In addition, the administration of triiodothyronine stimulated HAST in hypophysectomized rats of both sexes, and the extent of stimulation was nearly the same as observed in the male-type growth hormone treatment. PST-I, in contrast to HAST, showed no clear sex-related difference in hepatic content, and was not apparently affected by growth hormone or triiodothyronine.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic triiodothyronine sulfation and its regulation by growth hormone and triiodothyronine in rats.

The regulatory mechanism of cytosolic sulfation of T3 has been studied in rat liver. Sulfation of T3 is sexually differentiated in adult rats of Sprague-Dawley (SD), Fisher 344, and ACI strains. In SD strain, the male animals showed 4 times higher sulfating activity than did the females. The specific activity was decreased by hypophysectomy of male adult rats, but was not affected in the females. Thus, the sex-difference was abolished in the hypophysectomized condition. Supplement of human GH intermittently twice daily for 7 days, to mimic the male secretory pattern, increased T3 sulfating activity in both sexes of hypophysectomized rats, whereas continuous infusion to mimic a female secretory pattern had no appreciable effect. Cytosolic sulfation of T3 was decreased by 25 to 30% by thyroidectomy or propylthiouracil treatment of male adult rats, and was restored by the supplementation of T3 (50 micrograms/kg daily for 7 days) to thyroidectomized rats. Administration of T3 in hypophysectomized rats almost completely restored the sulfating activity in the males and increased the activity in the females. Cytosolic T3 sulfation was inhibited by the addition of known inhibitors of phenol sulfotransferase, pentachlorophenol or 2,6-dichloro-4-nitrophenol. These results indicate a role of pituitary GH in hepatic sulfation of thyroid hormones in rats. The data obtained also raise the possibility that GH may modify the effect of thyroid hormones on the pituitary by a feed-back mechanism through changing the level of a sex-dominant phenol sulfotransferase(s) in rat livers. T3 was also sulfated in hepatic cytosols of mouse, hamster, rabbit, dog, monkey, and human.(ABSTRACT TRUNCATED AT 250 WORDS)

Rat mitochondrial glycerol-3-phosphate dehydrogenase gene: multiple promoters, high levels in brown adipose tissue, and tissue-specific regulation by thyroid hormone.

Mitochondrial FAD-linked glycerol-3-phosphate dehydrogenase (mtGPDH) is one of the two enzymes of the glycerol phosphate shuttle. This shuttle transfers reducing equivalents from the cytoplasm to the mitochondria in a unidirectional, exothermic manner. Here, the isolation and characterization of the rat nuclear gene (Gpd2) encoding mtGPDH is reported. The mtGPDH gene spans 100 kb and consists of 17 exons. The use of alternate promoters was suggested by the presence of three different first exons and confirmed by transient expression for two of them. The first exons are expressed in a tissue-restricted manner. Exon 1a was found primarily in brain, exon 1b was used in all tissues examined, and exon 1c was detected predominantly in testis. Depending on the tissue, different transcript lengths were also observed: 5.9 kb (all tissues), 3.6 kb (skeletal muscle), and 2.5 kb (testis). The length isoforms are attributable to alternate splicing and polyadenylation site use. Very high mtGPDH mRNA levels were found in brown adipose tissue, 75 fold greater than in white adipose tissue. Thyroid hormone increased mtGPDH mRNA levels in liver and heart but not in brown adipose tissue, brain, or testis. This pattern corresponds to that of thyroid hormone-induced oxygen consumption and is consistent with a role for mtGPDH in thyroid hormone-induced thermogenesis. Both thyroid-responsive and nonresponsive tissues used promoter 1b, suggesting that tissue-specific factor(s) contribute to the tissue-restricted responsiveness to thyroid hormone.

Uncoupling protein-3 is a mediator of thermogenesis regulated by thyroid hormone, beta3-adrenergic agonists, and leptin.

Mitochondrial uncoupling proteins (UCPs) are transporters that are important for thermogenesis. The net result of their activity is the exothermic movement of protons through the inner mitochondrial membrane, uncoupled from ATP synthesis. We have cloned a third member of the UCP family, UCP3. UCP3 is expressed at high levels in muscle and rodent brown adipose tissue. Overexpression in yeast reduced the mitochondrial membrane potential, showing that UCP3 is a functional uncoupling protein. UCP3 RNA levels are regulated by hormonal and dietary manipulations. In contrast, levels of UCP2, a widely expressed UCP family member, showed little hormonal regulation. In particular, muscle UCP3 levels were decreased 3-fold in hypothyroid rats and increased 6-fold in hyperthyroid rats. Thus UCP3 is a strong candidate to explain the effects of thyroid hormone on thermogenesis. White adipose UCP3 levels were greatly increased by treatment with the beta3-adrenergic agonist, CL214613, suggesting another pathway for increasing thermogenesis. UCP3 mRNA levels were also regulated by dexamethasone, leptin, and starvation, albeit differently in muscle and brown adipose tissue. Starvation caused increased muscle and decreased BAT UCP3, suggesting that muscle assumes a larger role in thermoregulation during starvation. The UCP3 gene is located close to that encoding UCP2, in a chromosomal region implicated in previous linkage studies as contributing to obesity.

Thyroid hormone and other regulators of uncoupling proteins.

The role of the thyroid gland in the regulation of metabolic rate has been known since the last century. The knowledge that thyroid hormones increase energy expenditure, in part by lowering metabolic efficiency, dates from the 1950s. Presumably thyroid hormones regulate energy expenditure and efficiency by controlling the rate of transcription of specific genes. However, the number, identity, and relative contributions of these genes are not known. The uncoupling proteins (UCPs) are obvious candidates to mediate thyroid thermogenesis. UCP1 is not a major contributor, since thyrotoxicosis decreases UCP1 expression and inactivates brown fat. Discovery of UCP3 and its regulation by T3 in muscle is an exciting observation, consistent with a role for UCP3 in thyroid thermogenesis. Since free fatty acids appear to regulate UCP3 expression and T3 stimulates lipolysis, further experiments are required to determine if T3 regulation of UCP3 expression is direct or not.

Genomic organization and regulation by dietary fat of the uncoupling protein 3 and 2 genes.

Uncoupling protein-1 (UCP1) dissipates the transmitochondrial proton gradient as heat. UCP2 and UCP3 are two recently discovered homologues that also have uncoupling activity and thus presumably have a role in energy homeostasis. We now report the genomic structure of murine UCP3 (7 exons) and UCP2 (8 exons). UCP3 is approximately 8 kilobases upstream of UCP2. An UCP3 variant mRNA, UCP3S, was also found and characterized. The effect of a high fat diet (45% versus 10%) on UCP3 and UCP2 mRNA levels was measured. Eating the 45% fat diet for eight weeks caused greater weight gain in AKR and C57BL/6J mice than in the obesity-resistant A/J mice. The high fat diet increased muscle UCP3 expression twofold in C57BL/6J animals. UCP2 expression increased slightly on the 45% fat diet in white adipose of AKR mice, but not in A/J or C57BL/6J mice. In skeletal muscle, UCP2 expression showed little variation with diet. Thus, UCP2 and UCP3 expression levels change in response to diet-induced obesity, but the changes are modest and depend on the tissue and genotype. The data suggest that it is not a reduction in UCP2 or UCP3 expression that causes obesity in the susceptible mice.

Expression and functional characterization of a rat sulfotransferase (ST1A1) cDNA for sulfations of phenolic substrates in COS-1 cells.

A cDNA (PST-1) isolated from a rat liver cDNA library was expressed in COS-1 cells and found to encode a form of arylsulfotransferase (termed ST1A1), which sulfated p-nitrophenol, alpha-naphthol, minoxidil, beta-estradiol and dopamine, but not dehydroepiandrosterone and cortisol. ST1A1 showed a mobility identical with a major immunodetectable sulfotransferase contained in the livers of male and female rats in Western blots. In addition, ST1A1 mRNA was detected in the liver and extrahepatic tissues by Northern blots.

Drosophila 230-kD TFIID subunit, a functional homolog of the human cell cycle gene product, negatively regulates DNA binding of the TATA box-binding subunit of TFIID.

A Drosophila cDNA encoding the largest TFIID subunit (p230) was isolated using a degenerate oligodeoxynucleotide probe based on an amino acid sequence of the purified protein. The entire cDNA sequence contains an open reading frame encoding a polypeptide of 2068 amino acids, corresponding to a calculated molecular mass of 232 kD. The deduced amino acid sequence showed a strong sequence similarity with the protein encoded by a human gene (CCG1) implicated in cell cycle progression through G1, suggesting that p230 may be a target for cell cycle regulatory factors. The recombinant protein expressed in Sf9 cells via a baculovirus vector interacts directly with the TATA box-binding subunit of TFIID (TFIID tau or TBP) from Drosophila, human, and yeast. Surprisingly, recombinant p230 inhibits the TATA box-binding activity and function of TFIID tau, suggesting that p230 interactions with TFIID tau, and possible modulations thereof by other factors may play an important role in TFIID function.

Genomic structure and promoter analysis of the human obese gene.

The human gene encoding the homolog of the mouse obese (ob) gene was isolated and partially characterized. The human ob gene consists of three exons and two introns and spans about 18 kilobase pairs (kb), encoding a 3.5-kb cDNA. A 3-kb 5'-flanking region of the gene was cloned and transient transfection assay with luciferase reporter confirmed the promoter activity in differentiated F442-A adipocytes. Potential regulatory elements are discussed in this report.

The Drosophila 110-kDa transcription factor TFIID subunit directly interacts with the N-terminal region of the 230-kDa subunit.

Transcription initiation factor TFIID is a multimeric protein complex that plays a central role in transcriptional regulation by facilitating promoter responses to various activators. cDNAs encoding the 110-kDa subunit of Drosophila TFIID (p110) were isolated with a degenerate oligodeoxynucleotide probe based on an amino acid sequence of the purified protein. The entire cDNA sequence contains an open reading frame encoding a 921-amino acid polypeptide with a calculated molecular mass of 99,337 Da. The recombinant protein expressed in Sf9 cells via a baculovirus vector interacts directly with the 230-kDa subunit of TFIID (p230). Together with the previous observation that the TATA box-binding subunit of TFIID (TFIID tau or TBP) interacts directly with only p230 among the TFIID subunits, this result suggests that p110 forms a complex with TFIID tau via p230. A binding study using various p230 mutants indicated that both p110 and TFIID tau interact with the N-terminal 352-amino acid portion of p230, suggesting a functional communication between p110 and TFIID tau via p230 interactions.

Molecular cloning of cDNA encoding the small subunit of Drosophila transcription initiation factor TFIIF.

Transcription initiation factor TFIIF is a tetramer consisting of two large subunits (TFIIF alpha or RAP74) and two small subunits (TFIIF beta or RAP30). We report here the molecular cloning of a Drosophila cDNA encoding TFIIF beta. The cDNA clone contains an open-reading frame encoding a 277 amino acid polypeptide having a calculated molecular mass of 32,107 Da. Comparison of the deduced amino acid sequence with the corresponding sequences from vertebrates showed only 50% identity, with four insertion/deletion points. For transcription activity in a TFIIF-depleted Drosophila nuclear extract, both TFIIF alpha and TFIIF beta are essential. Moreover, Drosophila TFIIF beta interacts with both Drosophila and human TFIIF alpha in vitro. Thus we conclude that isolated cDNA encodes bona fide TFIIF beta. The structural domains of TFIIF beta and its sequence similarity to bacterial delta factors are discussed.

Enzymatic acetylation and sulfation of N-hydroxyarylamines in bacteria and rat livers.

In mammalian hepatic cytosol both acetyltransferase and sulfotransferase are involved in the activation of N-hydroxy derivatives of arylamines and arylamides. The role of acetyltransferase is also shown in Salmonella, whereas no rigid evidence is provided on the role of sulfotransferase in Salmonella. In Ames mutagenesis test without S9-mix, the number of revertants of Salmonella typhimurium TA98 induced was 10-fold higher with 2-hydroxyamino-3-methylimidazo[4,5-f] quinoline (N-hydroxy-IQ) than with 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (N-hydroxy-Glu-P-1). The extents of the binding to calf thymus DNA of N-hydroxy-Glu-P-1 were, however, 3.9 to 8.6-fold higher than that of N-hydroxy-IQ in both acetyl CoA- and PAPS-fortified rat hepatic cytosol systems. To understand the mechanism causing the apparent discrepancy between the results of the mutation and DNA binding, the activating capacities of cytosols of S. typhimurium TA98 and TA98/1,8-DNP6 strains on the binding of N-hydroxy-Glu-P-1 and N-hydroxy-IQ have been examined in comparison with those of rat livers. Although both N-hydroxyarylamines were activated by hepatic cytosols in the presence of PAPS, no significant DNA binding of these N-hydroxyarylamines was detected in the presence of PAPS and either one of the two strains of bacterial cytosols. In addition, both cytosols of TA98 and TA98/1,8-DNP6 strains showed no measurable activity on the sulfation of p-nitrophenol, suggesting no capacity for sulfotransferase-mediated activation of N-hydroxyarylamines in Salmonella. On the contrary, the extents of the acetyl CoA-dependent binding of N-hydroxy-IQ in cytosols of TA98, but not of TA98/1,8-DNP6, were respectively 6- and 9-fold higher than those in hepatic cytosols of male and female rats, although the extents of the binding of N-hydroxy-Glu-P-1 were rather higher in hepatic than in bacterial cytosols. In addition, the covalent binding of N-hydroxy-2-acetylaminofluorene to DNA was detected in hepatic, but not in bacterial cytosols, although the binding of N-hydroxy-2-aminofluorene was detectable in both hepatic and bacterial cytosols in the presence of acetyl CoA. These results indicate that the metabolic activating capacities of Salmonella and rat liver cytosols differ qualitatively, and the difference in the substrate specificity of acetyltransferase between Salmonella and rat livers may be involved, in part, in the difference of their DNA damage in bacteria and mammals.

Activation and detoxication of carcinogenic arylamines by sulfation.

Hepatic sulfation of heterocyclic and non-heterocyclic arylamines was studied to assess enzymes responsible for their metabolisms. Both 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)- and non-IQ-type (beta-carboline) heterocyclic amines were N-sulfated to form their sulfamates in cytosols of rat livers in the presence of 3'-phosphoadenosine-5'-phosphosulfate (PAPS). An arylsulfo-transferase, ST1A1, whose cDNA was isolated from a rat cDNA library, was expressed in COS-1 cells. The expressed enzyme catalyzed N-sulfation of IQ, but not appreciably those of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (Glu-P-I), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). N-Sulfation of heterocyclic amines except IQ was higher in hepatic cytosols of female rats than of male rats. These results suggest the involvement of at least plural forms of sulfotransferase on the N-sulfation. In addition, N-sulfation of IQ was also observed in cytosol of a human liver, suggesting that N-sulfation is one of the metabolic pathways of heterocyclic amines in humans as well as rats. Hepatic sulfotransferase also catalyzes metabolic activation of N-hydroxy derivatives of carcinogenic arylamines. Using anti-HAST (hydroxylarylamine sulfotransferase) antibodies and ST1A1 cDNA as screening probes, several cDNA clones were isolated from the cDNA library. A new member of arylsulfotransferase, ST1C1, whose cDNA shows considerable sequence similarity to ST1A1 cDNA, was found to catalyze O-sulfation of N-hydroxy-2-acetylaminofluorence by the cDNA expression in COS-1 cells. From the close similarity of ontogenic profile and sex-specific expression of ST1C1 and HAST, ST1C1 cDNA was shown to encode a major sulfotransferase (HAST) mediating the metabolic activation of N-hydroxyarylamines in rat livers. In addition, properties of PAPS-dependent N-hydroxyarylamine activation and sulfotransferase in human livers are also discussed.

Acetyltransferase and sulfotransferase which activate mutagens and carcinogens through O-esterification mechanisms.

The regulatory mechanism of acetyltransferase and sulfotransferase, which are involved in the activation of carcinogenic arylamines and their N-hydroxy derivatives, has been studied. Cytosolic N-acetylation of 2-aminofluorene (2-AF) in hamster liver and skin showed tri-modal distribution in the presence of acetyl CoA, whereas no clear segregation was detected in the N-hydroxyarylacetamide-supported N-acetylation and acetyl CoA-dependent O-acetylation of N-hydroxy-Glu-P-1. From hamster livers, two forms of acetyltransferase, AT-I and AT-II, were purified and characterized to have different catalytic and chemical properties. AT-I was detectable in all the hamsters examined, but AT-II was detected only in the animals showing high rates of 2-AF N-acetylation. Cross-matings of the intra- and inter-phenotypes of three different acetylators (rapid, intermediate, and slow) indicate the genetic inheritance of the arylamine N-acetylation, which follows a Mendelian co-dominant trait. Cytosolic sulfotransferase catalyzes the activation of N-hydroxyarylamines and N-hydroxyarylacetamides through the enzymatic O-sulfonylation. The reaction often shows a sex-related difference in rats. Among three sulfotransferases isolated (HAST I, II, and PST I), the level of HASTs was correlated with the 3'-phosphoadenosine 5'-phosphosulfate (PAPS)-dependent activating capacity of N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF) in rat livers. In addition, hepatic content of HASTs was decreased by hypophysectomy and restored by the intermittent administration of growth hormone, which mimics the male secretory profile. These results indicate that the sex-related difference in secretory profile of pituitary growth hormone is a major determinant of the male-dominant sulfation in this species.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of a placental enhancer for the human leptin gene.

Leptin is a hormone that regulates metabolic efficiency, energy expenditure, and food intake. Leptin is produced chiefly in adipose cells, but in humans, mRNA encoding leptin is also present in the placenta. Here we elucidate the basis for placental leptin production. The same promoter is used for adipose and placental transcription. An upstream enhancer functions in the JEG-3 and JAR choriocarcinoma cell lines but not in adipocytes or HeLa cells. The minimal positive acting region is 60 base pairs in length. This region is within a MER11 repetitive element, suggesting that human placental expression of leptin is the result of insertion of this element. Binding analyses demonstrated three protein binding sites, designated placental leptin enhancer elements (PLE)1, PLE2, and PLE3. PLE2 binds Sp1. Enhancer activity was reduced by mutation of the PLE1 or PLE3 sites but was unaffected by alteration of PLE2. Proteins binding to PLE3 were present in JEG-3 and human placental nuclear extracts but not in extracts from non-placental sources. Upon triplication, the PLE3 element was a strong enhancer in choriocarcinoma cells but not in HeLa cells. The protein binding to the PLE3 motif appears to be a novel, placenta-specific transcription factor.

Molecular cloning of Drosophila TFIID subunits.

Transcription initiation factor TFIID is a multisubunit complex containing a TATA-box-binding factor (TFIID tau/TBP) and associated polypeptide factors (TAFs) with sizes ranging from M(r) approximately 20,000 to > 200,000. As a result of direct promoter interactions, TFIID nucleates the assembly of RNA polymerase II and other initiation factors into a functional preinitiation complex. Although the native TFIID complex mediates both basal and activator-dependent transcription in reconstituted systems, TBP itself is competent for only basal transcription. Thus, TAFs are essential cofactors for regulated transcription. The complementary DNAs encoding the p230 (M(r) 230,000), p110 and p85 subunits of TFIID have recently been cloned. Here we report the molecular cloning and characterization of the p62, p42, p28 and p22 subunits. These participate in a network of heterogeneous protein-protein interactions within TFIID. Sequence similarities between p62/p42 and the histones H4/H3, respectively, suggest that these subunits have a functional relationship with chromatin.

Isolation and expression of a cDNA encoding a male-specific rat sulfotransferase that catalyzes activation of N-hydroxy-2-acetylaminofluorene.

A cDNA (ST1C1 cDNA) encoding a N-hydroxyarylamine sulfotransferase (HAST-I) was isolated from a liver cDNA library of a male adult rat and was expressed in COS-1 cells. ST1C1 cDNA (1363 base pairs) encoded a protein of 304 amino acids with a molecular mass of 35,768 daltons, which shared 50.7 and 46.1% sequence identity with rat aryl (ST1A1 (PST-1)) and estrogen (rOST) sulfotransferases, respectively. N-terminal amino acid sequences of three digested polypeptide fragments of HAST-I were completely identical with two portions of the ST1C1 amino acid sequence. The profile of age- and sex-related expression of ST1C1 mRNA was quite consistent with changes in the sulfating activity of N-hydroxyarylamine and HAST contents in rat livers. ST1C1 expressed in COS-1 cells catalyzed a sulfation of N-hydroxy-2-acetylaminofluorene (N-OH-AAF) at a rate of 4.98 nmol/mg of protein/min and mediated PAPS (3'-phosphoadenosine-5'-phosphosulfate)-dependent DNA binding of N-OH-AAF. Although ASTIV was believed to be responsible for the activation of N-OH-AAF, ST1A1 encoding an arylsulfotransferase ASTIV, showed only a marginal activity in a sulfation and covalent binding of N-OH-AAF. These data clearly indicate that ST1C1 cDNA codes a new form of a male-dominant sulfotransferase (HAST) responsible for the bioactivation of N-hydroxyarylamines in rat livers.