bims-supasi Biomed News
on Sulfation pathways and signalling
Issue of 2022‒01‒30
four papers selected by
Jonathan Wolf Mueller
University of Birmingham

  1. Drug Metab Dispos. 2022 Jan 24. pii: DMD-AR-2021-000685. [Epub ahead of print]
      Estrogen biosynthesis in human placental trophoblasts requires the hOAT4-mediated uptake of fetal derived precursors such as dehydroepiandrosterone-3-sulfate (DHEAS) and 16α-hydroxy-DHEA-S (16α-OH-DHEAS). Scant information is available concerning the contribution of fetal metabolites on the impact of placental estrogen precursor transport and the followed estrogen synthesis. This study substantiated the roles of bilirubin as well as bile acids (taurochenodeoxycholic acid, TCDCA; taurocholic acid, TCA; glycochenodeoxycholic acid, GCDCA; chenodeoxycholic acid, CDCA) on the inhibition of hOAT4-mediated uptake of probe substrate 6-carboxylfluorescein (6-CF) and DHEAS in stably transfected hOAT4-CHO cells, with the IC50 of 1.53 and 0.98 μM on 6-CF and DHEAS respectively for bilirubin, and 90.2, 129, 16.4 and 12.3 μM on 6-CF for TCDCA, GCDCA, TCA and CDCA. Bilirubin (2.5~10 μM) concentration-dependently inhibited the accumulation of estradiol precursor DHEAS in human choriocarcinoma JEG-3 cells (reduced by 60% at 10 μM) and primary human trophoblast cells (PHTCs, reduced by 80% at 10 μM). Further study confirmed that bilirubin (0.625~2.5 μM) concentration-dependently reduced the synthesis and secretion of estradiol in PHTCs, among which 2.5 μM bilirubin reduced the synthesis of estradiol by 30% and secretion by 35%. In addition, immunostaining and Western Blot results revealed a distinct down-regulation of hOAT4 protein expression in PHTCs pretreated with 2.5 μM bilirubin. In conclusion, this study demonstrated that bilirubin reduced the uptake of estrogen precursors and the followed synthesis of estradiol in human placenta via inhibition and down-regulation of OAT4. Significance Statement Fetal metabolites, especially bilirubin, was first identified with significant inhibitory effects on the hOAT4-mediated uptake of estrogen precursor DHEAS in hOAT4-CHO, JEG-3 and PHTCs. Bilirubin concentration-dependently suppressed the estradiol synthesis and secretion in PHTCs treated with DHEAS, which was synchronized with the decline of hOAT4 protein expression. Additionally, those identified bile acids exhibited a weaker inhibitory effect on the secretion of estradiol.
    Keywords:  bile acids; bilirubin; estrogens; placenta
  2. PLoS One. 2022 ;17(1): e0262854
      Chondroitin sulfate (CS) and its isomeric variant, dermatan sulfate (DS), are complex glycosaminoglycans (GAGs) which are ubiquitous components of the extracellular matrix in various tissues including the brain. CS and/or DS are known to bind to a variety of growth factors and regulate many cellular events such as proliferation and differentiation. Although the biological activities of CS and/or DS towards neural stem/progenitor cells (NSPCs) have been well investigated, the CS and/or DS of hematopoietic stem cells (HSCs) have not been fully characterized. Here, we analyzed GAGs on mononuclear cells of rat umbilical cord blood cells (UCB-MNCs). CS was detected in vascular intima and media of rat umbilical cord at embryonic day 19 (E19) by immunohistochemistry. The stem-cell-enriched-UCBCs (SCE-UCBCs), which were expanded from rat UCB-MNCs, expressed CS. CS chains are composed of repeating disaccharide units, which are classified into several types such as O-, A-, B-, C-, D-, and E-unit according to the number and positions of sulfation. A disaccharide composition analysis revealed that CS and/or DS were abundant in rat UCB-MNCs as well as in their expanded SCE-UCBCs, while the amount of heparan sulfate (HS) was less. The degree of sulfation of CS/DS was relatively low and the major component in UCB-MNCs and SCE-UCBCs was the A-unit. A colony-forming cell assay revealed that the percentage of colony-forming cells decreased in culture with CS degradation enzyme. The CS and/or DS of UCBCs may be involved in biological activities such as stem cell proliferation and/or differentiation.
  3. Cell Tissue Res. 2022 Jan 24.
      Chondroitin sulfate proteoglycan (CSPG), one of the major extracellular matrices, plays an important part in organogenesis. Its core protein and chondroitin sulfate (CS) chain have a specific biological function. To elucidate the role of CS in the developmental and healing process of the dental pulp, we performed an experimental tooth replantation in CS N-acethylgalactosaminyltransferase-1 (T1) gene knockout (KO) mice. We also performed cell proliferation assay and qRT-PCR analysis for the WT and T1KO primary dental pulp cells using T1-siRNA technique and external CS. During tooth development, CS was diffusely expressed in the dental papilla, and with dental pulp maturation, CS disappeared from the differentiated areas, including the odontoblasts. In fully developed molars, CS was restricted to the root apex region colocalizing with Gli1-positive cells. In the healing process after tooth replantation, CD31-positive cells accumulated in the CS-positive stroma in WT molars. In T1KO molars, the appearance of Ki67- and Gli1-positive cells in the dental pulp was significantly fewer than in WT molars in the early healing stage, and collagen I-positive reparative dentin formation was not obvious in T1KO mice. In primary culture experiments, siRNA knockdown of T1 gene significantly suppressed cell proliferation in WT dental pulp cells, and the mRNA expression of cyclin D1 and CD31 was significantly upregulated by external CS in T1KO dental pulp cells. These results suggest that CS is involved in the cell proliferation and functional differentiation of dental pulp constituent cells, including vascular cells, in the healing process of dental pulp tissue after tooth injury.
    Keywords:  Chondroitin sulfate; Dental pulp; Heparan sulfate; Tooth replantation; Vessels
  4. Front Endocrinol (Lausanne). 2021 ;12 814373
      Bromophenols (BPs), known as an important environmental contaminant, can cause endocrine disruption and other chronic toxicity. The study aimed to investigate the potential inhibitory capability of BPs on four human sulfotransferase isoforms (SULT1A1, SULT1A3, SULT1B1 and SULT1E1) and interpret how to interfere with endocrine hormone metabolism. P-nitrophenol(PNP) was utilized as a nonselective probe substrate, and recombinant SULT isoforms were utilized as the enzyme resources. PNP and its metabolite PNP-sulfate were analyzed using a UPLC-UV detecting system. SULT1A1 and SULT1B1 were demonstrated to be the most vulnerable SULT isoforms towards BPs' inhibition. To determine the inhibition kinetics, 2,4,6-TBP and SULT1A3 were selected as the representative BPs and SULT isoform respectively. The competitive inhibition of 2,4,6-TBP on SULT1A3. The fitting equation was y=90.065x+1466.7, and the inhibition kinetic parameter (Ki) was 16.28 µM. In vitro-in vivo extrapolation (IVIVE) showed that the threshold concentration of 2,4,6-TBP to induce inhibition of SULT1A3 was 1.628 µM. In silico docking, the method utilized indicated that more hydrogen bonds formation contributed to the stronger inhibition of 3,5-DBP than 3-BP. In conclusion, our study gave the full description of the inhibition of BPs towards four SULT isoforms, which may provide a new perspective on the toxicity mechanism of BPs and further explain the interference of BPs on endocrine hormone metabolism.
    Keywords:  bromophenols (BPs); endocrine hormones; in vitro-in vivo extrapolation (IVIVE); inhibition; sulfotransferase (SULT)