Impact of genetic polymorphisms on the sulfation of dehydroepiandrosterone and 17-β estradiol by human cytosolic sulfotransferase SULT2B1a

Dehydroepiandrosterone (DHEA) is considered an endogenous steroid hormone precursor, and 17-ß Estradiol (E2) is one of the estrogen steroid hormones. Of the thirteen known human cytosolic sulfotransferases (SULTs), SULT2B1a has been shown to be expressed in steroid hormone-responsive tissues such as the prostate, ovary, and placenta, as well as the fetal brain. Previous studies have demonstrated that SULT2B1a is capable of sulfating 3β-hydroxysteroids such as DHEA and pregnenolone. The present study aimed to investigate the effects of human SULT2B1 SNPs on the enzymatic characteristics of SULT2B1a allozymes in mediating the sulfation of DHEA and E2. To inspect the effects of single nucleotide polymorphisms of the SULT2B1 gene on the sulfation of DHEA and E2 by SULT2B1a allozymes, 13 recombinant SULT2B1a allozymes were produced, expressed, and purified using established procedures. 13 SULT 2B1a nonsynonymous missense coding SNPs (cSNPs) were selected among numerous identified human SULT 2B1a SNPs by a comprehensive database search. The corresponding cDNAs, packaged in pGEX-2TK expression vector, and encoding the selected 13 SULT2B1a allozymes, have been generated by performing site-directed mutagenesis. These were then bacterially expressed in BL21 E. coli cells and purified using glutathione-Sepharose affinity chromatography. The purified allozymes were tested for their ability to sulfonate DHEA and E2. In terms of the kinetic parameters, the wild-type SULT2B1a exhibited higher enzyme affinity towards DHEA than with E2. In comparison with the wild-type SULT2B1a, the purified allozymes displayed differential sulfating activities towards DHEA and E2. Accordingly, these findings indicate an apparent effect of SULT2B1 cSNPs on the sulfating activities of SULT2B1a allozymes toward DHEA and E2, and may provide for a better understanding of the pharmacokinetics of DHEA and E2 in individuals with differing SULT2B1a genotypes.

Radix Bupleuri is one of the most widely used herbal medicines in China for the treatment of fever, pain, and/or chronic inflammation. Quercitrin, epicatechin, and rutin, the flavonoids present in Radix Bupleuri, have been reported to display anti-inflammatory, antitumor, and antioxidant biological activities among others. Sulfation has been reported to play an important role in the metabolism of flavonoids. In this study, we aimed to systematically identify the human cytosolic sulfotransferase enzymes that are capable of catalyzing the sulfation of quercitrin, epicatechin, and rutin. Of the thirteen known human cytosolic sulfotransferases, three (cytosolic sulfotransferase 1A1, cytosolic sulfotransferase 1C2, and cytosolic sulfotransferase 1C4) displayed sulfating activity toward quercitrin, three (cytosolic sulfotransferase 1A1, cytosolic sulfotransferase 1A3, and cytosolic sulfotransferase 1C4) displayed sulfating activity toward epicatechin, and six (cytosolic sulfotransferase 1A1, cytosolic sulfotransferase 1A2, cytosolic sulfotransferase 1A3, cytosolic sulfotransferase 1B1, cytosolic sulfotransferase 1C4, and cytosolic sulfotransferase 1E1) displayed sulfating activity toward rutin. The kinetic parameters of the cytosolic sulfotransferases that showed the strongest sulfating activities were determined. To investigate the effects of genetic polymorphisms on the sulfation of quercitrin, epicatechin, and rutin, individual panels of cytosolic sulfotransferase allozymes previously prepared were analyzed and shown to display differential sulfating activities toward each of the three flavonoids. Taken together, these results provided a biochemical basis underlying the metabolism of quercitrin, epicatechin, and rutin through sulfation in humans.

Sulfation of ritodrine by the human cytosolic sulfotransferases (SULTs): Effects of SULT1A3 genetic polymorphism

This study aimed to identify human cytosolic sulfotransferases (SULTs) that are capable of mediating hyperoside sulfation and examine the impact of genetic polymorphisms on their sulfating activity. Of the thirteen known human SULTs analyzed, five (1A1, 1A2, 1A3, 1C2, and 1C4) displayed sulfating activity toward hyperoside. Kinetic parameters of SULT1C4 that showed the strongest sulfating activity were determined. Ten SULT1C4 allozymes previously prepared were shown to display differential sulfating activities toward hyperoside, revealing clearly the functional impact of SULT1C4 genetic polymorphisms. These findings provided a robust biochemical foundation for further studies on the metabolism of hyperoside by sulfation.

Sulfation of Flavonoids and Other Phenolic Dietary Compounds by the Human Cytosolic Sulfotransferases

Buprenorphine, pentazocine, and naloxone are opioid drugs used for the treatment of pain and opioid dependence or overdose. Sulfation as catalyzed by the cytosolic sulfotransferases (SULTs) is involved in the metabolism of a variety of xenobiotics including drug compounds. Sulfation of opioid drugs has not been well investigated. The current study was designed to examine the sulfation of three opioid drugs, buprenorphine, pentazocine, and naloxone, in HepG2 human hepatoma cells and to identify the human SULT(s) responsible for their sulfation. Analysis of the spent media of HepG2 cells, metabolically labeled with [(35)S]sulfate in the presence of each of the three opioid drugs, showed the generation and release of their [(35)S]sulfated derivatives. A systematic analysis using eleven known human SULTs revealed SULT1A3 and SULT2A1 as the major responsible SULTs for the sulfation of, respectively, pentazocine and buprenorphine; whereas three other SULTs, SULT1A1, SULT1A2, and SULT1C4, were capable of sulfating naloxone. Enzymatic assays using combinations of these opioid drugs as substrates showed significant inhibitory effects in the sulfation of buprenorphine and pentazocine by naloxone. Differential sulfating activities toward the three opioid drugs were detected in cytosol or S9 fractions of human lung, liver, kidney, and small intestine. Collectively, these results imply that sulfation may play a role in the metabolism of buprenorphine, pentazocine, and naloxone in vivo.

Phenylephrine and salbutamol are drugs that are used widely to treat diseases/disorders, such as nasal congestion, hypotension, and asthma, in individuals of different age groups. Human cytosolic sulfotransferase (SULT) SULT1A3 has been shown to be critically involved in the metabolism of these therapeutic agents. This study was carried out to investigate the effects of single nucleotide polymorphisms of human SULT1A3 and SULT1A4 genes on the sulfation of phenylephrine and salbutamol by SULT1A3 allozymes. Wild-type and SULT1A3 allozymes, prepared previously by site-directed mutagenesis in conjunction with bacterial expression and affinity purification, were analyzed for sulfating activity using an established assay procedure. Purified SULT1A3 allozymes, in comparison with the wild-type enzyme, showed differential sulfating activities toward phenylephrine and salbutamol. Kinetic studies showed further significant variations in their substrate-binding affinity and catalytic activity toward phenylephrine and salbutamol. The results obtained showed clearly the differential enzymatic characteristics of SULT1A3 allozymes in mediating the sulfation of phenylephrine and salbutamol. This information may contribute toward a better understanding of the pharmacokinetics of these two drugs in individuals with distinct SULT1A3 and/or SULT1A4 genotypes.

Buprenorphine, pentazocine, and naloxone are opioid drugs used for the treatment of pain and opioid dependence or overdose. Sulfation as catalyzed by the cytosolic sulfotransferases (SULTs) is involved in the metabolism of a variety of xenobiotics including drug compounds. Sulfation of opioid drugs has not been well investigated. The current study was designed to examine the sulfation of three opioid drugs, buprenorphine, pentazocine, and naloxone, in HepG2 human hepatoma cells and to identify the human SULT(s) responsible for their sulfation. Analysis of the spent media of HepG2 cells, metabolically labeled with [35S]sulfate in the presence of each of the three opioid drugs, showed the generation and release of their [35S]sulfated derivatives. A systematic analysis using eleven known human SULTs revealed SULT1A3 and SULT2A1 as the major responsible SULTs for the sulfation of, respectively, pentazocine and buprenorphine; whereas three other SULTs, SULT1A1, SULT1A2, and SULT1C4, were capable of sulfating naloxone. Enzymatic assays using combinations of these opioid drugs as substrates showed significant inhibitory effects in the sulfation of buprenorphine and pentazocine by naloxone. Differential sulfating activities toward the three opioid drugs were detected in cytosol or S9 fractions of human lung, liver, kidney, and small intestine. Collectively, these results imply that sulfation may play a role in the metabolism of buprenorphine, pentazocine, and naloxone in vivo. Keywords: Cytosolic sulfotransferase, sulfation, opioids, buprenorphine, pentazocine, naloxone

Previous studies have revealed sulfation as a major pathway for the metabolism of hesperetin, naringenin and apigenin. The current study was designed to identify the human cytosolic sulfotransferase (SULT) enzyme(s) capable of sulfating these flavonoid compounds. Of the thirteen human SULTs, six (1A1, 1A2, 1A3, 1B2, 1C4, 1E1) displayed significant sulfating activity toward hesperetin, five (1A1, 1A2, 1A3, 1B2, 1C4) displayed sulfating activity towards naringenin, and four (1A1, 1A2, 1A3, 1C4) showed sulfating activity towards apigenin. Of the four human organ specimens tested, liver and intestine cytosols displayed much higher hesperetin-, naringenin- and apigenin-sulfating activity than lung and kidney cytosols. Moreover, sulfation of hesperetin, naringenin and apigenin was shown to take place in HepG2 human hepatoma cells and Caco-2 human colon adenocarcinoma cells under cultured conditions. Taken together, these results provided a biochemical basis underlying the metabolism of hesperetin, naringenin and apigenin through sulfation in humans.

Steroid sulfation by expressed human cytosolic sulfotransferases

The cytosolic sulfotransferase (SULT) SULT2A1 is known to mediate the sulfation of DHEA as well as some other hydroxysteroids such as pregnenolone. The present study was designed to investigate how genetic polymorphisms of the human SULT2A1 gene may affect the sulfation of DHEA and pregnenolone. Online databases were systematically searched to identify human SULT2A1 single nucleotide polymorphisms (SNPs). Of the 98 SULT2A1 non-synonymous coding SNPs identified, seven were selected for further investigation. Site-directed mutagenesis was used to generate cDNAs encoding these seven SULT2A1 allozymes, which were expressed in BL21 Escherichia coli cells and purified by glutathione-Sepharose affinity chromatography. Enzymatic assays revealed that purified SULT2A1 allozymes displayed differential sulfating activity toward both DHEA and pregnenolone. Kinetic analyses showed further differential catalytic efficiency and substrate affinity of the SULT2A1 allozymes, in comparison with wild-type SULT2A1. These findings provided useful information concerning the effects of genetic polymorphisms on the sulfating activity of SULT2A1 allozymes.

The cytosolic sulfotransferase (SULT) SULT2A1 is known to mediate the sulfation of dehydroepiandrosterone (DHEA) as well as many other sterols and steroids. The present study was designed to investigate how genetic polymorphisms of the human SULT2A1 gene may affect the sulfation of DHEA. Online databases were comprehensively searched to identify human SULT2A1 single nucleotide polymorphisms (SNPs). Of the 98 SULT2A1 non‐synonymous coding SNPs identified, seven were selected for further investigation. Site‐directed mutagenesis was used to generate cDNAs encoding these seven SULT2A1 allozymes, which were expressed in BL21 E. coli cells and purified by glutathione‐Sepharose affinity chromatography. Enzymatic assays revealed that purified SULT2A1 allozymes displayed differential sulfating activity toward DHEA. Kinetic analyses showed further differential catalytic efficiency and substrate affinity of the SULT2A1 allozymes, in comparison with wild‐type SULT2A1. These findings provided useful information concerning the effects of genetic polymorphisms on the sulfating activity of SULT2A1 allozymes.Support or Funding InformationThis work was supported in part by a grant from National Institutes of Health (Grant # R03HD071146).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Budesonide, a synthetic glucocorticosteroid, is used in the treatment of asthma and allergic reactions, rhinitis, and inflammatory bowel disease. It is distributed as a mixture of two epimers, 22R and 22S, and has a high ratio of topical to systemic activity due to extensive first-pass metabolism to metabolites with minimal activity. Previous studies have shown that the epimers are metabolized by the cytochrome P450 monooxygenase system. Metabolism and inactivation of the epimers by the phase II enzymes has not been well characterized. This study describes the conjugation of budesonide by human cytosolic sulfotransferases (SULTs). Seven human SULTs were analyzed to determine which were capable of catalyzing the sulfation of the epimers of budesonide. Only dehydroepiandrosterone-sulfotransferase (DHEA-ST, SULT2A1) was capable of forming a sulfated budesonide product. The epimeric forms of budesonide display different kinetic activities with the 22R epimer having a 3.5-fold greater rate of sulfation activity than the 22S epimer. The structure of budesonide shows two hydroxyl sites that are potential sites for sulfate conjugation, but analysis by mass spectrometry indicates the formation of only a monosulfated budesonide product. A modeling approach was used to define the site of sulfation as that of the 21-hydroxyl group. Although sulfation of budesonide by DHEA-ST may not be an important factor in its use as an antiasthmatic, intestinal and hepatic sulfation will be important for its proposed systemic use as an anti-inflammatory agent.

Tocopherols are essential micronutrients for mammals widely known as potent lipid-soluble antioxidants that are present in cell membranes. Recent studies have demonstrated that most of the carboxychromanol (CEHC), a tocopherol metabolite, in the plasma exists primarily in sulfate- and glucuronide-conjugated forms. To gain insight into the enzymatic sulfation of tocopherols and their metabolites, a systematic investigation was performed using all 14 known human cytosolic sulfotransferases (SULTs). The results showed that the members of the SULT1 family displayed stronger sulfating activities toward tocopherols and their metabolites. These enzymes showed a substrate preference for γ-tocopherol over α-tocopherol and for γ-CEHC over other CEHCs. Using A549 human lung epithelial cells in a metabolic labeling study, a similar trend in the sulfation of tocopherols and CEHCs was observed. Collectively, the results obtained indicate that SULT-mediated enzymatic sulfation of tocopherols and their metabolites is a significant pathway for regulation of the homeostasis and physiological functions of these important compounds.

Disclosure: M.M. Jung: None. D.R. Seib: None. M. Idrissi: None. H.W. Chen: None. K.K. Soma: None. Sucrose (table sugar) is a common added sugar in foods and beverages. Sucrose intake is high worldwide, yet little is known about how sucrose affects the brain and hormones. We designed an isocaloric, macro/micro-nutrient matched control diet (1% kcal sucrose) and high-sucrose diet (26% kcal sucrose) paradigm where the two diets only differ in kcal from sucrose. In this paradigm, maternal high-sucrose diet intake alters glucocorticoids (GCs) which are steroid hormones that regulate numerous physiological processes including the stress response. 16 wk of maternal sucrose intake (10 wk before mating, 3 wk during gestation, and 3 wk during lactation) increases blood and brain corticosterone levels in adult female offspring. Moreover, 13 wk of maternal sucrose intake (10 wk before mating and 3 wk during gestation) increases 11-deoxycorticosterone (DOC, corticosterone precursor) and 11-dehydrocorticosterone (DHC, corticosterone metabolite) in maternal serum, and increases aldosterone in fetal blood and brain at embryonic day 19.5 (E19.5). These results suggest that long-term maternal sucrose intake is a stressor that alters GC and aldosterone signalling. It is unclear whether a maternal high-sucrose diet only during gestation alters fetal steroid levels, or whether long-term sucrose consumption before mating is necessary. Here, we investigate the effects of maternal sucrose intake during gestation only on GCs and aldosterone in the fetal blood and brain. We hypothesize that maternal sucrose intake only during gestation will alter GC and aldosterone signaling in the fetus. We predict that maternal sucrose consumption during gestation alone will increase GC and aldosterone levels in the fetal blood and brain. Female Long-Evans rats were fed either a high-sucrose diet or a control diet starting E0.5 (day of mating confirmation) (n=15/diet). On E19.5, we collected fetal brain and blood and microdissected the regions of the fetal brain that are sensitive to GCs and aldosterone: nucleus accumbens, amygdala, hypothalamus, ventral hippocampus, and ventral tegmental area. We measured a panel of 15 steroids including GCs and aldosterone in the fetal brain (0.8-1.6 mg/region) and blood (5 µL) using liquid chromatography-tandem mass spectrometry, the gold standard for steroid quantification. Maternal high-sucrose diet intake during gestation alone did not alter maternal food intake, maternal body mass, or litter size, but increased the percentage of male offspring per litter. Maternal sucrose intake did not alter DOC, corticosterone, or DHC levels in the fetal blood and brain regions. Aldosterone was not detected in the fetal blood and brain. These results suggest that maternal sucrose intake during gestation alone does not alter GC and aldosterone levels in the developing fetus and that a longer duration of maternal sucrose intake is needed to alter offspring endocrine physiology. Presentation: 6/1/2024