Differential roles of human monoamine (M)-form and simple phenol (P)-form phenol sulfotransferases in drug metabolism

Evolution and multiple functions of sulfonation and cytosolic sulfotransferases across species

Organisms have conversion systems for sulfate ion to take advantage of the chemical features. The use of biologically converted sulfonucleotides varies in an evolutionary manner, with the universal use being that of sulfonate donors. Sulfotransferases have the ability to transfer the sulfonate group of 3'-phosphoadenosine 5'-phosphosulfate to a variety of molecules. Cytosolic sulfotransferases (SULTs) play a role in the metabolism of low-molecular-weight compounds in response to the host organism's living environment. This review will address the diverse functions of the SULT in evolution, including recent findings. In addition to the diversity of vertebrate sulfotransferases, the molecular aspects and recent studies on bacterial and plant sulfotransferases are also addressed.

Molecular cloning and characterization of common marmoset SULT1C subfamily members that catalyze the sulfation of thyroid hormones

Cytosolic sulfotransferase SULT1C subfamily is one of the most flexible gene subfamily during mammalian evolution. The physiological functions of SULT1C enzymes still remain to be fully understood. In this study, common marmoset (Callithrix jacchus), a promising primate animal model, was used to investigate the functional relevance of the SULT1C subfamily. Gene database search revealed three intact SULT1C genes and a pseudogene in its genome. These four genes were named SULT1C1, SULT1C2, SULT1C3P, and SULT1C5, according to the sequence homology and gene location. Since SULT1C5 is the orthologous gene for human SULT1C2P, we propose, here, to revisit the designation of human SULT1C2P to SULT1C5P. Purified recombinant SULT1C enzymes showed sulfating activities toward a variety of xenobiotic compounds and thyroid hormones. Kinetic analysis revealed high catalytic activities of SULT1C1 and SULT1C5 for 3,3'-T2. It appears therefore that SULT1C isoforms may play a role in the thyroid hormone metabolism in common marmoset.

SULT genetic polymorphisms: physiological, pharmacological and clinical implications

INTRODUCTION

Cytosolic sulfotransferases (SULTs)-mediated sulfation is critically involved in the metabolism of key endogenous compounds, such as catecholamines and thyroid/steroid hormones, as well as a variety of drugs and other xenobiotics. Studies performed in the past three decades have yielded a good understanding about the enzymology of the SULTs and their structural biology, phylogenetic relationships, tissue/organ-specific/developmental expression, as well as the regulation of the SULT gene expression. An emerging area is related to the functional impact of the SULT genetic polymorphisms.

AREAS COVERED

The current review aims to summarize our current knowledge about the above-mentioned aspects of the SULT research. An emphasis is on the information concerning the effects of the polymorphisms of the SULT genes on the functional activity of the SULT allozymes and the associated physiological, pharmacological, and clinical implications.

EXPERT OPINION

Elucidation of how SULT SNPs may influence the drug-sulfating activity of SULT allozymes will help understand the differential drug metabolism and eventually aid in formulating personalized drug regimens. Moreover, the information concerning the differential sulfating activities of SULT allozymes toward endogenous compounds may allow for the development of strategies for mitigating anomalies in the metabolism of these endogenous compounds in individuals with certain SULT genotypes.

Sulphation of acetaminophen by the human cytosolic sulfotransferases: a systematic analysis

Sulphation is known to be critically involved in the metabolism of acetaminophen in vivo. This study aimed to systematically identify the major human cytosolic sulfotransferase (SULT) enzyme(s) responsible for the sulphation of acetaminophen. A systematic analysis showed that three of the twelve human SULTs, SULT1A1, SULT1A3 and SULT1C4, displayed the strongest sulphating activity towards acetaminophen. The pH dependence of the sulphation of acetaminophen by each of these three SULTs was examined. Kinetic parameters of these three SULTs in catalysing acetaminophen sulphation were determined. Moreover, sulphation of acetaminophen was shown to occur in HepG2 human hepatoma cells and Caco-2 human intestinal epithelial cells under the metabolic setting. Of the four human organ samples tested, liver and intestine cytosols displayed considerably higher acetaminophen-sulphating activity than those of lung and kidney. Collectively, these results provided useful information concerning the biochemical basis underlying the metabolism of acetaminophen in vivo previously reported.

Sulfation of opioid drugs by human cytosolic sulfotransferases: metabolic labeling study and enzymatic analysis

The current study was designed to examine the sulfation of eight opioid drugs, morphine, hydromorphone, oxymorphone, butorphanol, nalbuphine, levorphanol, nalorphine, and naltrexone, in HepG2 human hepatoma cells and human organ samples (lung, liver, kidney, and small intestine) 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 eight opioid drugs, showed the generation and release of corresponding [35S]sulfated derivatives. Five of the eight opioid drugs, hydromorphone, oxymorphone, butorphanol, nalorphine, and naltrexone, appeared to be more strongly sulfated in HepG2 cells than were the other three, morphine, nalbuphine, and levorphanol. Differential sulfating activities toward the opioid drugs were detected in cytosol or S9 fractions of human lung, liver, small intestine, and kidney, with the highest activities being found for the liver sample. A systematic analysis using eleven known human SULTs and kinetic experiment revealed SULT1A1 as the major responsible SULTs for the sulfation of oxymorphone, nalbuphine, nalorphine, and naltrexone, SULT1A3 for the sulfation of morphine and hydromorphone, and SULT2A1 for the sulfation of butorphanol and levorphanol. Collectively, the results obtained imply that sulfation may play a significant role in the metabolism of the tested opioid drugs in vivo.