Sulphation catalysed by the human cytosolic sulphotransferases--chemical defence or molecular terrorism?
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Animals↗
Biomedical subjects
M W Coughtrie
Publications and source records attributed to M W Coughtrie.
Design, production and characterization of antibodies discriminating between the phenol- and monoamine-sulphating forms of human phenol sulphotransferase.
1. Phenol sulphotransferases (PSTs) are important enzymes in xenobiotic and endobiotic detoxication, and a key component of the body's chemical defence mechanism. 2. Human phenol-(P-PST) and monoamine-(M-PST) sulphating forms of PST share 93% amino acid sequence identity, and to date the various antibodies produced against PSTs all recognize both enzymes. 3. We have identified two peptides based on the cDNA-derived amino acid sequences of human P-PST and M-PST, which elicited for the first time antibodies capable of discriminating between these highly homologous enzymes. 4. These antibodies represent valuable tools for studying the expression, distribution and function of human phenol sulphotransferases.
Amino Acid Sequence↗
The in vivo regulation of hepatic and renal glucose-6-phosphatase by thyroxine.
The hepatic and renal microsomal glucose-6-phosphatase enzymes are situated with their active site in the lumen of the endoplasmic reticulum and for normal enzyme activity in vivo transport systems are needed for the substrates and products of the enzyme. We have shown that thyroxine activates the kidney glucose-6-phosphatase enzyme and the liver glucose 6-phosphate transport systems. In contrast, in hypophysectomised and adrenalectomised animals, thyroxine activates the transport systems and the enzyme in both liver and kidney.
Adrenalectomy↗
Effects of hypophysectomy and thyroxine on the expression of hepatic oestrogen, hydroxysteroid and phenol sulphotransferases.
Sulphation in rats, and other mammals, is carried out by a family of sulphotransferase isoenzymes, which can be further subdivided into oestrogen, hydroxysteroid and phenol sulphotransferases. We have examined the effects of hypophysectomy on the activity and expression of representative members of the three major sulphotransferase sub-families in male Wistar rat liver cytosols, and have found that the different sub-families are subject to differential regulation by pituitary hormones. Our data show that in male rat liver hydroxysteroid sulphotransferases activity was increased, oestrogen sulphotransferases activity was not altered and phenol sulphotransferases activity was reduced. Further, we have studied the effect on sulphotransferase expression of administration of thyroxine and dexamethasone to hypophysectomized rats. Treatment of hypophysectomized rats with thyroxine virtually abolished oestrogen sulphotransferase activity in male rat liver but had no effect on hydroxysteroid sulphotransferase or phenol sulphotransferase activity. Treatment of hypophysectomized rats with dexamethasone had no effect on sulphotransferase activities. Quantitative immunoblot analysis of liver cytosols showed that these changes in enzyme activity were related to changes in levels of the respective enzyme proteins.
Animals↗
Human platelet phenolsulfotransferases: cDNA cloning, stable expression in V79 cells and identification of a novel allelic variant of the phenol-sulfating form.
We have isolated cDNA clones encoding phenol- and monoamine-sulfating phenolsulfotransferases, using the reverse transcription-polymerase chain reaction method with human platelet mRNA as template. These cDNAs were stably expressed in the Chinese hamster fibroblast cell line V79 and their substrate specificities towards known sulfotransferase isoenzyme-selective compounds determined. The nucleotide and derived amino acid sequences of the monoamine-sulfating form were identical to those previously identified in human liver and brain, but the cDNA for the human platelet phenol-sulfating form we isolated contained 5 and 2 amino acid changes from the two previously published sequences from human liver and brain, suggesting that we have identified a new allelic variant of human phenol-sulfating phenolsulfotransferase.
Alleles↗
Reduced platelet phenolsulphotransferase activity towards dopamine and 5-hydroxytryptamine in migraine.
OBJECTIVE: The sulphation of the neurotransmitters dopamine and 5-hydroxytryptamine, and of the prototypical xenobiotic 4-nitrophenol, by phenolsulphotransferases was measured in platelet homogenates prepared from a group of migraine sufferers and a group of control subjects. RESULTS: The activity of the M form of phenolsulphotransferase, responsible for the sulphation of dopamine and 5-hydroxytryptamine was significantly reduced in the migraine population, by 28% with dopamine as substrate and by 20% with 5-hydroxytryptamine. The activity of the P form of the enzyme towards 4-nitrophenol was the same in both groups. We also report that the selective inhibition of P form phenolsulphotransferase by red wine is much more potent than previously thought, with a 2000-fold dilution of dealcoholised red wine having the ability to inhibit sulphation by this enzyme by 50%. CONCLUSION: Our findings suggest that a reduced capacity for sulphation and inactivation of biogenic amines and catecholamines may be related to susceptibility to migraine.
Adult↗
Differential localisation of UDP-glucuronosyltransferase in kidney during human embryonic and fetal development.
The aim of our study was to localise UDP-glucuronosyltransferase (UDPGT) in the developing mesonephric and metanephric kidneys of the human embryo and fetus, using immunohistochemical methods and an antibody preparation with broad specificity to the human isoforms. In embryonic and early fetal development of the metanephric kidney, UDPGT is located primarily in derivatives of the ureteric bud such as the ureter, pelvis, calyces and collecting ducts. This early predominance of UDPGT to ureteric bud derivatives declines by mid-fetal life: a) as nephrons evolve and develop they become increasingly UDPGT immunoreactive such that in mature metanephric kidney, the proximal tubules are highly UDPGT reactive, with other elements of the nephron also immunopositive (albeit at lower reactivities) and b) with the formation of an immunonegative transitional epithelium in ureter, pelvis and calyces, the reactivity retained in collecting ducts is only a small proportion of the total. The distribution of UDPGT immunoreactivity is relatively uniform in proximal tubular cells throughout development. This is in contrast to collecting ducts where, in fetal life, this reactivity is displaced to apices and bases by intracellular glycogen deposits. Parietal cells of Bowman's capsule are immunoreactive, but glomeruli are negative. In mesonephric kidney, as early as 32 days post-ovulation, tubules and the mesonephric duct are UDPGT immunoreactive and mesonephric immunopositivity overlaps with that in the developing metanephric kidney.
Embryonic and Fetal Development↗
Human fetal adrenal hydroxysteroid sulphotransferase: cDNA cloning, stable expression in V79 cells and functional characterisation of the expressed enzyme.
Dehydroepiandrosterone sulphate (DHEAS) is a major adrenal secretory product, particularly in the fetus where it serves as a substrate for oestrogen biosynthesis by the placenta. The enzyme in the adrenal responsible for synthesising DHEAS, hydroxysteroid sulphotransferase (HST), is therefore essential for human development. We have isolated a full-length cDNA clone, encoding human fetal adrenal HST, and constructed a stable cell line expressing it by transfection into V79 Chinese hamster lung fibroblast cells. This cDNA was essentially identical to that isolated from adult human liver, where the role of HST is less well understood. This recombinant cell line allowed determination of the substrate specificity and kinetic properties of this enzyme towards various steroid hormones, and by comparison of these activities with human liver cytosol we have shown that HST is the major sulphotransferase responsible for the sulphation of DHEA, androsterone and pregnenolone in man and that, functionally, the hepatic and adrenal enzymes are very similar. The expressed HST was also active with testosterone, cortisol (although at low levels) and the xenobiotic 17 alpha-ethinyloestradiol, but not with oestrone or 1-naphthol. We have therefore created a valuable resource for the study of this important enzyme.
Adrenal Glands↗
Induction of hepatic estrogen sulfotransferase expression by hypophysectomy in female rats.
We have examined the effects of hypophysectomy and treatment with thyroxine (T4) on enzyme activity and expression (as determined by immunoblot analysis) of members of the three principal sulfotransferase (ST) sub-families (phenol STs, PST; estrogen STs, EST; hydroxysteroid STs, HST) in cytosols prepared from female Wistar rat livers. The results demonstrate that in female rat liver cytosol, EST activity was decreased by treatment with T4, increased following hypophysectomy and that treatment of hypophysectomized animals with T4 also greatly reduced EST activity. T4 had no significant effect on PST or HST activity in normal animals, but it decreased HST activity in hypophysectomized rat liver cytosol. Immunoblot analysis of these cytosols with antibodies recognising HST and PST indicated that where changes in enzyme activity occurred they mirrored changes in enzyme protein expression. In normal adult female rat livers, EST protein is not expressed, and the small residual activity results predominantly from the action of HST. Hypophysectomy induced EST activity and the expression of EST enzyme protein in female rat liver cytosol, and T4 treatment of hypophysectomized animals reduced the activity to below normal levels without reducing the corresponding enzyme protein levels, indicating that T4 regulation of EST in females is via a post-translational mechanism.
Animals↗
Preparation and characterization of anti-peptide antibodies directed against human phenol and hydroxysteroid sulphotransferases.
Sulphotransferases (STs) catalyze the sulphation and, in general, detoxication of a large number of xenobiotics and endogenous compounds. A total of six synthetic peptides derived from the cDNA-derived amino acid sequences of the human phenol-sulphating form of phenosulphotransferase (P-PST) and human hydroxysteroid sulphotransferase (HST)--three from each sequence--were separately conjugated to the carrier protein keyhole limpet hemocyanin, and used to immunize rabbits. One successful antibody preparation was produced from among the P-PST peptides, and two from the HST peptides. On immunoblot analysis following SDS/PAGE, the anti-P-PST antibodies recognized two major forms of phenol ST in man, P-PST and the monoamine-sulphating form of PST, M-PST, and the two antibody preparations against HST recognized the human HST. These experiments demonstrate that it is possible to design specific antibodies against human sulphotransferases based on their amino acid sequences.
Adjuvants, Immunologic↗
Differential expression of hepatic oestrogen, phenol and dehydroepiandrosterone sulphotransferases in genetically obese diabetic (ob/ob) male and female mice.
Sulphotransferases (STs) are a family of closely related enzymes playing a key role in regulation of the bioavailability and activity of important endogenous molecules such as steroid hormones. A relationship between the expression of steroid STs and the diabetic state has been demonstrated in various laboratory animal models, and steroid sulphates such as dehydroepiandrosterone sulphate are known to have anti-diabetic properties. In order to further our understanding of the molecular basis for the association of steroid hormone sulphation and diabetes, we have examined the expression of oestrogen, phenol and dehydroepiandrosterone (DHEA) STs in mice carrying the obesity mutation (ob), which in the homozygous state (ob/ob) produces mice which are obese and diabetic. Our data show that, in male mice, ST activities towards oestrone (E1), oestriol (E3), DHEA and the xenobiotic 1-naphthol are elevated in ob/ob mice, whereas in female mice, only the oestrogen ST activities were elevated, with the DHEA and 1-naphthol ST activities reduced. Using antibodies directed against oestrogen ST, it was demonstrated that the induction of E1 and E3 ST activity in ob/ob mice correlated with the expression of an ST isoenzyme not constitutively expressed in control mouse liver.
Animals↗
Immunolocalization of dehydroepiandrosterone sulfotransferase in normal and pathologic human adrenal gland.
Dehydroepiandrosterone sulfotransferase (DHEA-ST) catalyzes the conversion of dehydroepiandrosterone (DHEA) to dehydroepiandrosterone sulfate (DHEA-S) in the adrenals. Both DHEA and DHEA-S are quantitatively the most important corticosteroids in human. In this study, DHEA-ST was immunolocalized in normal (5 cases) and neoplastic human adrenal glands (33 cases), using a specific IgG fraction raised against the enzyme. DHEA-ST was present in almost all the zona reticularis cells and some cortical cells demonstrating lipid depletion in the zona fasciculata but not in the zona glomerulosa of the normal adrenal. This finding is consistent with adrenocorticotrophic hormone dependency of the enzyme expression. In adrenocortical adenoma, DHEA-ST immunoreactivity was observed in all the cases of Cushing's adenoma, adenoma associated with pre-Cushing's syndrome, nonfunctioning, hormonally inactive adenoma, and two of seven cases of aldosteronoma, but distribution of immunoreactivity was markedly heterogeneous among the adenoma cases. In attached non-neoplastic adrenal glands of the adenoma, intense and diffuse immunoreactivity was observed in the zona reticularis cells in all the cases of aldosteronoma and five of six of the nonfunctioning hormonally inactive adenoma, but DHEA-ST immunoreactivity was not observed or sporadic in the attached adrenal glands of Cushing's adenoma and adenoma with pre-Cushing's syndrome. These results in the attached adrenal gland may be correlated with decreased DHEA-ST expression due to autonomous neoplastic cortisol secretion and subsequent adrenocorticotrophic hormone suppression. In adrenocortical carcinoma, DHEA-ST was observed in all the cases, but the relative immunointensity of carcinoma cells was weak compared to that of the zona reticularis of the normal adrenal and adenoma.
Adrenal Cortex Neoplasms↗
Sulphation of N-hydroxy-4-aminobiphenyl and N-hydroxy-4-acetylaminobiphenyl by human foetal and neonatal sulphotransferase.
Sulphation of the genotoxic compounds N-hydroxy-4-aminobiphenyl (N-OH-4ABP) and N-hydroxy-4-acetylaminobiphenyl (N-OH-4AABP) was determined in cytosolic preparations of human foetal, neonatal and adult liver and foetal and neonatal adrenal gland. Sulphotransferase (ST) activity capable of sulphating these compounds was present in foetal liver and adrenal gland by 14 weeks of gestation. Sulphation of N-OH-4ABP was higher in foetal and neonatal adrenal cytosol than was sulphation of N-OH-4AABP and in general, N-OH-4ABP ST activity was also greater than that towards 1-naphthol. In foetal and neonatal liver cytosol the sulphation of N-OH-4ABP was also higher than that of N-OH-4AABP (approximately 2-fold). In adult liver cytosols, however, N-OH-4AABP ST activity was higher than that for N-OH-4ABP and 1-naphthol sulphation. Aromatic hydroxylamines and hydroxamic acids are known to be converted by sulphotransferase into reactive, electrophilic compounds capable of reacting with DNA. Our data show that the human foetus and neonate have the capacity to sulphate these compounds and thus is able to produce the reactive mutagenic metabolites. Therefore, this class of genotoxic compounds may be bioactivated by humans during development--a time when they are most vulnerable to the effects of genotoxins.
Adrenal Glands↗
Identification of a new adult human liver sulfotransferase with specificity for endogenous and xenobiotic estrogens.
We present evidence for the existence of a previously undescribed sulfotransferase isoenzyme in adult human liver which sulfates endogenous and xenobiotic estrogens (estrone and 17 alpha-ethinylestradiol). The enzyme was resolved from other sulfotransferases using anion exchange chromatography and further purified by gel filtration and affinity chromatography. Using antibodies against rat liver estrogen and hydroxysteroid sulfotransferases, it was shown that the adult human estrogen sulfotransferase has a subunit molecular weight of 33kDa, is immunologically related to its rat counterpart and also to the human phenolsulfotransferase enzyme family, but not to human hydroxysteroid sulfotransferase.
Arylsulfotransferase↗
Function and regulation of UDP-glucuronosyltransferase genes in health and liver disease: report of the Seventh International Workshop on Glucuronidation, September 1993, Pitlochry, Scotland.
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Animals↗
Phenolsulphotransferase: localization in kidney during human embryonic and fetal development.
The aim of our study was to localize phenolsulphotransferase (PST) in the developing mesonephric and metanephric kidneys of the human embryo and fetus using immunohistochemical methods with an antibody preparation recognizing members of the human phenolsulphotransferase enzyme family. In embryonic and early fetal development of the metanephric kidney, PST is located primarily in derivatives of the ureteric bud such as the ureter, pelvis, calyces and collecting ducts. This predominance declines by mid-fetal life: first, as nephrons evolve and develop they become increasingly PST-immunoreactive such that in mature metanephric kidney, the proximal tubules are highly PST-reactive, with other elements of the nephron also immunopositive (albeit at lower reactivities) and secondly, with the formation of an immunonegative transitional epithelium in ureter, pelvis and calyces, the reactivity retained in collecting ducts is only a small proportion of the total. The distribution of PST immunoreactivity is relatively uniform in proximal tubular cells throughout development, in contrast to collecting ducts, where, in fetal life, this reactivity is displaced to apices and bases by intracellular glycogen deposits. Mesonephric kidney tubules and the mesonephric duct are PST-immunoreactive and although mesonephric immunopositivity overlaps with that in the developing metanephric kidney the renal contribution to sulphation is absent or low at a time when the developing conceptus is most vulnerable to the potential toxic effects of teratogens.
Adult↗
Sulfation of endogenous compounds and xenobiotics--interactions and function in health and disease.
Sulfation is a major detoxication mechanism for endogenous compounds and xenobiotics performed by a family of sulfotransferase isoenzymes. Understanding the normal cellular functions of these different sulfotransferases and the way in which endogenous and exogenous factors are able to influence their activity and expression will provide us with the information necessary to develop novel therapeutic strategies for conditions where sulfation may be implicated. This concept is discussed and is illustrated by examples including adverse drug reactions, fetal development and cancer.
Amino Acid Sequence↗
Sulfation of carcinogenic aromatic hydroxylamines and hydroxamic acids by rat and human sulfotransferases: substrate specificity, developmental aspects and sex differences.
Sulfation of the carcinogen N-hydroxy-2-acetylaminofluorene (N-OH-AAF) and structurally related hydroxamic acids by rat and human sulfotransferases was studied. There was a clear sex and age difference in the sulfation of N-OH-AAF and the other hydroxamic acids by rat liver cytosols; adult male rats had the highest sulfation activity. Experiments with purified aryl sulfotransferase IV (AST IV) indicated that the high expression of this enzyme in male rat liver may be responsible for these differences. No such sex or age difference was found for the sulfation of aromatic hydroxylamines. In cytosols of adult human livers, sulfation activity towards aromatic hydroxamic acids and hydroxylamines was clearly present, but activities were much lower than in rat liver cytosols. Sulfation activity towards these compounds was also found in fetal and neonatal liver and adrenals. These compounds probably are sulfated by several different sulfotransferases in humans.
Aging↗