Τίτλος:
NFE2-Related transcription factor 2 coordinates antioxidant defense with thyroglobulin production and iodination in the thyroid gland
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
Background: The thyroid gland has a special relationship with oxidative stress. While generation of oxidative substances is part of normal iodide metabolism during thyroid hormone synthesis, the gland must also defend itself against excessive oxidation in order to maintain normal function. Antioxidant and detoxification enzymes aid thyroid cells to maintain homeostasis by ameliorating oxidative insults, including during exposure to excess iodide, but the factors that coordinate their expression with the cellular redox status are not known. The antioxidant response system comprising the ubiquitously expressed NFE2-related transcription factor 2 (Nrf2) and its redox-sensitive cytoplasmic inhibitor Kelch-like ECH-associated protein 1 (Keap1) defends tissues against oxidative stress, thereby protecting against pathologies that relate to DNA, protein, and/or lipid oxidative damage. Thus, it was hypothesized that Nrf2 should also have important roles in maintaining thyroid homeostasis. Methods: Ubiquitous and thyroid-specific male C57BL6J Nrf2 knockout (Nrf2-KO) mice were studied. Plasma and thyroids were harvested for evaluation of thyroid function tests by radioimmunoassays and of gene and protein expression by real-time polymerase chain reaction and immunoblotting, respectively. Nrf2-KO and Keap1-KO clones of the PCCL3 rat thyroid follicular cell line were generated using CRISPR/Cas9 technology and were used for gene and protein expression studies. Software-predicted Nrf2 binding sites on the thyroglobulin enhancer were validated by site-directed in vitro mutagenesis and chromatin immunoprecipitation. Results: The study shows that Nrf2 mediates antioxidant transcriptional responses in thyroid cells and protects the thyroid from oxidation induced by iodide overload. Surprisingly, it was also found that Nrf2 has a dramatic impact on both the basal abundance and the thyrotropin-inducible intrathyroidal abundance of thyroglobulin (Tg), the precursor protein of thyroid hormones. This effect is mediated by cell-autonomous regulation of Tg gene expression by Nrf2 via its direct binding to two evolutionarily conserved antioxidant response elements in an upstream enhancer. Yet, despite upregulating Tg levels, Nrf2 limits Tg iodination both under basal conditions and in response to excess iodide. Conclusions: Nrf2 exerts pleiotropic roles in the thyroid gland to couple cell stress defense mechanisms to iodide metabolism and the thyroid hormone synthesis machinery, both under basal conditions and in response to excess iodide. © 2018 Mary Ann Liebert, Inc.
Συγγραφείς:
Ziros, P.G.
Habeos, I.G.
Chartoumpekis, D.V.
Ntalampyra, E.
Somm, E.
Renaud, C.O.
Bongiovanni, M.
Trougakos, I.P.
Yamamoto, M.
Kensler, T.W.
Santisteban, P.
Carrasco, N.
Ris-Stalpers, C.
Amendola, E.
Liao, X.-H.
Rossich, L.
Thomasz, L.
Juvenal, G.J.
Refetoff, S.
Sykiotis, G.P.
Περιοδικό:
Thyroid Research
Εκδότης:
MARY ANN LIEBERT INC PUBL
Λέξεις-κλειδιά:
antioxidant; iodide; nfe2 related transcription factor 2; protein precursor; reactive oxygen metabolite; thyroglobulin; thyroid hormone; thyrotropin; transcription factor; unclassified drug; antioxidant; iodide; iodine; KEAP1 protein, human; kelch like ECH associated protein 1; Nfe2l2 protein, mouse; oxygen; reactive oxygen metabolite; thyroglobulin; thyroid hormone; transcription factor Nrf2, animal cell; animal experiment; animal tissue; antioxidant responsive element; Article; binding site; cell stress; chromatin immunoprecipitation; controlled study; enhancer region; gene expression; genetic transfection; immunoblotting; in vitro study; iodination; male; mouse; mutagenesis; nonhuman; oxidation; PCCL3 cell line; priority journal; promoter region; protein expression; protein isolation; protein synthesis; radioimmunoassay; rat; real time polymerase chain reaction; regulatory mechanism; software; thyroid follicular cell; thyroid function test; thyroid gland; thyroid hormone synthesis; animal; blood; C57BL mouse; cell line; chemistry; cytoplasm; genetics; homeostasis; human; knockout mouse; metabolism; oxidation reduction reaction; oxidative stress; thyroid gland, Animals; Antioxidants; Cell Line; Cytoplasm; Homeostasis; Humans; Iodides; Iodine; Kelch-Like ECH-Associated Protein 1; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; NF-E2-Related Factor 2; Oxidation-Reduction; Oxidative Stress; Oxygen; Promoter Regions, Genetic; Rats; Reactive Oxygen Species; Thyroglobulin; Thyroid Gland; Thyroid Hormones
DOI:
10.1089/thy.2018.0018
