Transcriptional Regulation of Cytosolic Sulfotransferase 1C2 by Vitamin D Receptor in LS180 Human Colorectal Adenocarcinoma Cells

The Protective Effect of 1,25(OH)2D3 on Myocardial Function is Mediated via Sirtuin 3-Regulated Fatty Acid Metabolism

Energy substrate imbalance is a major cause of cardiac dysfunction. Vitamin D/vitamin D receptor (VD/VDR) deficiency is involved in the pathogenesis of various cardiac diseases; however, the exact underlying mechanism remains unclear. The aim of this study was to investigate whether vitamin D modulates mitochondrial fatty acid oxidase via sirtuin 3 signaling to protect the myocardium. 1-Alpha-hydroxylase-defficient mice exhibited a high metabolic rate and lower myocardial contractility than wild-type mice. Sirtuin 3 upregulation was detected in high-fat diet-fed mice receiving vitamin D3 compared with that in high-fat diet-fed mice. Both sirtuin 3 blockade and knockout inhibited the VD/VDR-induced downregulation of fatty acid oxidase in myocardial mitochondria. VD/VDR suppressed fatty acid metabolism by upregulating sirtuin 3 and lowering mitochondrial fat uptake, thereby improving myocardial function and balancing energy substrates, rather than by altering fat endocytosis and exocytosis.

Regulation of Cytosolic Sulfotransferases in Models of Human Hepatocyte Development

Cytosolic sulfotransferases (SULTs) are expressed during early life and therefore metabolize endogenous and xenobiotic chemicals during development. Little is currently known about the regulation of individual SULTs in the developing human liver. We characterized SULT expression in primary cultures of human fetal hepatocytes and the HepaRG model of liver cell differentiation. SULT1A1 (transcript variants 1-4), SULT1C2, SULT1C4, SULT1E1, and SULT2A1 were the most abundant transcripts in human fetal hepatocytes. In HepaRG cells, SULT1B1, SULT1C2/3/4, and SULT1E1 mRNA levels increased during the transition from proliferation to confluency and then decreased as the cells underwent further differentiation. By contrast, SULT2A1 mRNA levels increased during differentiation, whereas SULT1A1 and SULT2B1 mRNA levels remained relatively constant. The temporal patterns of SULT1C2, SULT1E1, and SULT2A1 protein content were consistent with those observed at the mRNA level. To identify regulators of SULT expression, cultured fetal hepatocytes and HepaRG cells were treated with a panel of lipid- and xenobiotic-sensing receptor activators. The following effects were observed in both fetal hepatocytes and HepaRG cells: 1) liver X receptor activator treatment increased SULT1A1 transcript variant 5 levels; 2) vitamin D receptor activator treatment increased SULT1C2 and SULT2B1 mRNA levels; and 3) farnesoid X receptor activator treatment decreased SULT2A1 expression. Activators of aryl hydrocarbon receptor, constitutive androstane receptor, pregnane X receptor, and peroxisome proliferator-activated receptors produced additional gene-dependent effects on SULT expression in HepaRG cells. These findings suggest that SULT-regulating chemicals have the potential to modulate physiologic processes and susceptibility to xenobiotic stressors in the developing human liver.

Implications of sulfotransferase activity in interindividual variability in drug response: clinical perspective on current knowledge

The interindividual variability in drug response is a major issue in clinical practice and in drug development. Sulfoconjugation is an important Phase II reaction catalyzed by cytosolic sulfotransferases (SULTs), playing a major role in homeostatic functions, xenobiotic detoxification, and carcinogen bioactivation. SULT display wide interindividual variability, explained only partially by genetic variation, suggesting that other non-genetic, epigenetic, and environmental influences could be major determinants of variability in SULT activity. This review focuses on the factors known to influence SULT variability in expression and activity and the available evidence regarding the impact of SULT variability on drug response.