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Tinant G, Neefs I, Das K, Rees JF, Larondelle Y, Debier C. Methylmercury displays pro-adipogenic properties in rainbow trout preadipocytes. CHEMOSPHERE 2021; 263:127917. [PMID: 33297014 DOI: 10.1016/j.chemosphere.2020.127917] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 07/27/2020] [Accepted: 08/03/2020] [Indexed: 06/12/2023]
Abstract
Methylmercury (MeHg) is a ubiquitous contaminant largely found in aquatic environments, especially in species at high trophic level such as salmonids. The aim of this study was to evaluate the effects of MeHg on adipocyte differentiation and lipid metabolism in rainbow trout. Primary cultured preadipocytes were exposed to increasing concentrations of MeHg during six days with or without a hormonal cocktail. Main results showed a dose-dependent intracellular accumulation of neutral lipids with a preferential uptake of n-3 polyunsaturated fatty acids. Interestingly, this accumulation occurred after a fairly low uptake of MeHg by preadipocytes and was maintained after the cellular exposure to MeHg. In membrane phospholipids, arachidonic acid (20:4 n-6) was released in a dose-dependent manner. At the transcriptional level, the expression of several adipocyte-specific genes (perilipin 2 and apolipoprotein Eb) as well as lipid-related genes (fatty acid synthase and fatty acid binding protein 11a) was up-regulated in preadipocytes exposed to MeHg. These results highlight for the first time the disrupting effect of MeHg in trout adipocyte metabolism, providing new insights regarding the role of environmental pollutants in adipose tissue dysfunction and related pathologies.
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Affiliation(s)
- Gilles Tinant
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium.
| | - Ineke Neefs
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium
| | - Krishna Das
- Laboratory of Oceanology, Université de Liège, 11 Allée Du 6 Août, B6C, 4000, Liège, Belgium
| | - Jean-François Rees
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium
| | - Yvan Larondelle
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium
| | - Cathy Debier
- Louvain Institute of Biomolecular Science and Technology (LIBST), Université catholique de Louvain, Croix Du Sud 4-5/L7.07.03, 1348, Louvain-la-Neuve, Belgium.
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Hinz KM, Meyer K, Kinne A, Schülein R, Köhrle J, Krause G. Structural insights into thyroid hormone transport mechanisms of the L-type amino acid transporter 2. Mol Endocrinol 2015; 29:933-42. [PMID: 25945809 DOI: 10.1210/me.2015-1044] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Thyroid hormones (THs) are transported across cell membranes by different transmembrane transporter proteins. In previous studies, we showed marked 3,3'-diiodothyronine (3,3'-T2) but moderate T3 uptake by the L-type amino acid transporter 2 (Lat2). We have now studied the structure-function relationships of this transporter and TH-like molecules. Our Lat2 homology model is based on 2 crystal structures of the homologous 12-transmembrane helix transporters arginine/agmatine antiporter and amino acid/polyamine/organocation transporter. Model-driven mutagenesis of residues lining an extracellular recognition site and a TH-traversing channel identified 9 sensitive residues. Using Xenopus laevis oocytes as expression system, we found that side chain shortening (N51S, N133S, N248S, and Y130A) expanded the channel and increased 3,3'-T2 transport. Side chain enlargements (T140F, Y130R, and I137M) decreased 3,3'-T2 uptake, indicating channel obstructions. The opposite results with mutations maintaining (F242W) or impairing (F242V) uptake suggest that F242 may have a gating function. Competitive inhibition studies of 14 TH-like compounds revealed that recognition by Lat2 requires amino and carboxylic acid groups. The size of the adjacent hydrophobic group is restricted. Bulky substituents in positions 3 and 5 of the tyrosine ring are allowed. The phenolic ring may be enlarged, provided that the whole molecule is flexible enough to fit into the distinctly shaped TH-traversing channel of Lat2. Taken together, the next Lat2 features were identified 1) TH recognition site; 2) TH-traversing channel in the center of Lat2; and 3) switch site that potentially facilitates intracellular substrate release. Together with identified substrate features, these data help to elucidate the molecular mechanisms and role of Lat2 in T2 transport.
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Affiliation(s)
- Katrin M Hinz
- Leibniz-Institut für Molekulare Pharmakologie (FMP) (K.M.H., K.M., A.K., R.S., G.K.), 13125 Berlin, Germany; and Institut für Experimentelle Endokrinologie (J.K.), Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Katja Meyer
- Leibniz-Institut für Molekulare Pharmakologie (FMP) (K.M.H., K.M., A.K., R.S., G.K.), 13125 Berlin, Germany; and Institut für Experimentelle Endokrinologie (J.K.), Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Anita Kinne
- Leibniz-Institut für Molekulare Pharmakologie (FMP) (K.M.H., K.M., A.K., R.S., G.K.), 13125 Berlin, Germany; and Institut für Experimentelle Endokrinologie (J.K.), Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Ralf Schülein
- Leibniz-Institut für Molekulare Pharmakologie (FMP) (K.M.H., K.M., A.K., R.S., G.K.), 13125 Berlin, Germany; and Institut für Experimentelle Endokrinologie (J.K.), Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Josef Köhrle
- Leibniz-Institut für Molekulare Pharmakologie (FMP) (K.M.H., K.M., A.K., R.S., G.K.), 13125 Berlin, Germany; and Institut für Experimentelle Endokrinologie (J.K.), Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Gerd Krause
- Leibniz-Institut für Molekulare Pharmakologie (FMP) (K.M.H., K.M., A.K., R.S., G.K.), 13125 Berlin, Germany; and Institut für Experimentelle Endokrinologie (J.K.), Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
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Chen Y, Sjölinder M, Wang X, Altenbacher G, Hagner M, Berglund P, Gao Y, Lu T, Jonsson AB, Sjölinder H. Thyroid hormone enhances nitric oxide-mediated bacterial clearance and promotes survival after meningococcal infection. PLoS One 2012; 7:e41445. [PMID: 22844479 PMCID: PMC3402396 DOI: 10.1371/journal.pone.0041445] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 06/21/2012] [Indexed: 12/04/2022] Open
Abstract
Euthyroid sick syndrome characterized by reduced levels of thyroid hormones (THs) is observed in patients with meningococcal shock. It has been found that the level of THs reflects disease severity and is predictive for mortality. The present study was conducted to investigate the impact of THs on host defense during meningococcal infection. We found that supplementation of thyroxine to mice infected with Neisseria meningitidis enhanced bacterial clearance, attenuated the inflammatory responses and promoted survival. In vitro studies with macrophages revealed that THs enhanced bacteria-cell interaction and intracellular killing of meningococci by stimulating inducible nitric oxide synthase (iNos)-mediated NO production. TH treatment did not activate expression of TH receptors in macrophages. Instead, the observed TH-directed actions were mediated through nongenomic pathways involving the protein kinases PI3K and ERK1/2 and initiated at the membrane receptor integrin αvβ3. Inhibition of nongenomic TH signaling prevented iNos induction, NO production and subsequent intracellular bacterial killing by macrophages. These data demonstrate a beneficial role of THs in macrophage-mediated N. meningitidis clearance. TH replacement might be a novel option to control meningococcal septicemia.
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Affiliation(s)
- Yao Chen
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Mikael Sjölinder
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Xiao Wang
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Georg Altenbacher
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Matthias Hagner
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Pernilla Berglund
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Yumin Gao
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Ting Lu
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Ann-Beth Jonsson
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
| | - Hong Sjölinder
- Department of Genetics, Microbiology and Toxicology, Stockholm University, Stockholm, Sweden
- * E-mail:
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