Biochemistry, Cellular and Molecular Biology, and Physiological Roles of the Iodothyronine Selenodeiodinases

Bianco, Antonio C.

doi:10.1210/er.23.1.38

Cited by 660 publications

(814 citation statements)

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“…Induction of Raldh1 was similar to that of the T3 catabolic enzyme Dio3 , previously shown to be upregulated by T3 (Bianco et al, 2002) and with a TRE in its promoter (Barca‐Mayo et al, 2011) and which was increased over six‐fold in T3‐treated slices compared to controls (Fig. 3B; P = 0.0003).…”

Section: Resultssupporting

confidence: 74%

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Thyroid hormone activation of retinoic acid synthesis in hypothalamic tanycytes

Stoney

Helfer

Rodrigues

et al. 2015

Glia

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Thyroid hormone (TH) is essential for adult brain function and its actions include several key roles in the hypothalamus. Although TH controls gene expression via specific TH receptors of the nuclear receptor class, surprisingly few genes have been demonstrated to be directly regulated by TH in the hypothalamus, or the adult brain as a whole. This study explored the rapid induction by TH of retinaldehyde dehydrogenase 1 (Raldh1), encoding a retinoic acid (RA)‐synthesizing enzyme, as a gene specifically expressed in hypothalamic tanycytes, cells that mediate a number of actions of TH in the hypothalamus. The resulting increase in RA may then regulate gene expression via the RA receptors, also of the nuclear receptor class. In vivo exposure of the rat to TH led to a significant and rapid increase in hypothalamic Raldh1 within 4 hours. That this may lead to an in vivo increase in RA is suggested by the later induction by TH of the RA‐responsive gene Cyp26b1. To explore the actions of RA in the hypothalamus as a potential mediator of TH control of gene regulation, an ex vivo hypothalamic rat slice culture method was developed in which the Raldh1‐expressing tanycytes were maintained. These slice cultures confirmed that TH did not act on genes regulating energy balance but could induce Raldh1. RA has the potential to upregulate expression of genes involved in growth and appetite, Ghrh and Agrp. This regulation is acutely sensitive to epigenetic changes, as has been shown for TH action in vivo. These results indicate that sequential triggering of two nuclear receptor signalling systems has the capability to mediate some of the functions of TH in the hypothalamus. GLIA 2016;64:425–439

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Section: Resultssupporting

confidence: 74%

“…Deiodinase 3 ( Dio3 ) has previously been shown to be directly induced by T3 (Barca‐Mayo et al, 2011; Bianco et al, 2002) and was used as a positive control. Dio3 was strongly upregulated in the hypothalamus of T3‐treated rats (Fig.…”

Section: Resultsmentioning

confidence: 99%

Thyroid hormone activation of retinoic acid synthesis in hypothalamic tanycytes

Stoney

Helfer

Rodrigues

et al. 2015

Glia

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“…If TR␤2 acts directly to repress S opsin transcription, binding of the T3 ligand is required to alter the TR␤2 receptor state and recruit coregulators. At these early embryonic times, T4 is available through maternal circulation and the D2 deiodinase that produces T3 is generally expressed in tissues of the central nervous system (CNS) at early embryonic stages (Bianco et al, 2002). Because TR␤2 is necessary for S opsin dorsal repression, as well as dorsal and ventral M opsin activation, and TR␤2 is uniformly expressed across the retina, there is no need to invoke a gradient in T3 availability during the early embryonic period.…”

Section: Thyroid Hormone Receptors Act As Sensors Of Thyroid Hormone T3mentioning

confidence: 99%

Transient expression of thyroid hormone nuclear receptor TRβ2 sets S opsin patterning during cone photoreceptor genesis

Applebury

Farhangfar

Glösmann

et al. 2007

Developmental Dynamics

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Cone photoreceptors in the murine retina are patterned by dorsal repression and ventral activation of S opsin. TR␤2, the nuclear thyroid hormone receptor ␤ isoform 2, regulates dorsal repression. To determine the molecular mechanism by which TR␤2 acts, we compared the spatiotemporal expression of TR␤2 and S opsin from embryonic day (E) 13 through adulthood in C57BL/6 retinae. TR␤2 and S opsin are expressed in cone photoreceptors only. Both are transcribed by E13, and their levels increase with cone genesis. TR␤2 is expressed uniformly, but transiently, across the retina. mRNA levels are maximal by E17 at completion of cone genesis and again minimal before P5. S opsin is also transcribed by E13, but only in ventral cones. Repression in dorsal cones is established by E17, consistent with the occurrence of patterning during cone cell genesis. The uniform expression of TR␤2 suggests that repression of S opsin requires other dorsalspecific factors in addition to TR␤2. The mechanism by which TR␤2 functions was probed in transgenic animals with TR␤2 ablated, TR␤2 that is DNA binding defective, and TR␤2 that is ligand binding defective. These studies show that TR␤2 is necessary for dorsal repression, but not ventral activation of S opsin. TR␤2 must bind DNA and the ligand T3 (thyroid hormone) to repress S opsin. Once repression is established, T3 no longer regulates dorsal S opsin repression in adult animals. The transient, embryonic action of TR␤2 is consistent with a role (direct and/or indirect) in chromatin remodeling that leads to permanent gene silencing in terminally differentiated, dorsal cone photoreceptors.

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“…Occurring transiently near the end of the first trimester, there is direct stimulation of the thyroid gland by an increase in the concentration of human chorionic gonadotrophin that may lead temporarily to a slightly increased concentration of free thyroxine. Finally, significant changes occur in the peripheral metabolism of maternal thyroid hormones during the second half of gestation, mainly under the influence of placental type 3 iodothyronine deiodinase 2 .…”

Section: Introductionmentioning

confidence: 99%

The importance of iodine nutrition during pregnancy

Glinoer

2007

Public Health Nutr.

197

131

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Objective: To examine the importance of iodine nutrition during pregnancy. Design: Review of existing literature of iodine in pregnancy. Setting: Population surveys and metabolic studies. Subjects: Pregnant women. Results: The main changes in thyroid function associated with pregnancy are due to an increase in hormone requirements that begin in the first trimester of gestation. This increase can only be met by a proportional increase in hormone production, something that depends directly upon the availability of iodine. When dietary iodine is lacking, an adequate physiological adaptation is difficult to achieve and is progressively replaced by pathological alterations that occur in parallel with the degree and duration of iodine deprivation. Conclusions: Iodine prophylaxis should be given systematically to women during pregnancy. In most public health programmes dealing with the correction of iodine deficiency disorders, iodised salt has been used as the preferred means to deliver iodine to households. Iodised salt, however, is not the ideal means of delivering iodine in the specific instances of pregnancy, breast-feeding and complementary feeding because of the need to limit salt intake during these periods. In European countries, presently it is proposed that iodine is given to pregnant women and breast-feeding mothers by systematically administering multivitamin tablets containing iodine in order to reach the recommended dietary allowance of 250 mg iodine day -1 .

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Biochemistry, Cellular and Molecular Biology, and Physiological Roles of the Iodothyronine Selenodeiodinases

Cited by 660 publications

References 0 publications

Thyroid hormone activation of retinoic acid synthesis in hypothalamic tanycytes

Thyroid hormone activation of retinoic acid synthesis in hypothalamic tanycytes

Transient expression of thyroid hormone nuclear receptor TRβ2 sets S opsin patterning during cone photoreceptor genesis

The importance of iodine nutrition during pregnancy

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