The type 2 and type 3 iodothyronine deiodinases play important roles in coordinating development in Rana catesbeiana tadpoles.

@article{Becker1997TheT2,
  title={The type 2 and type 3 iodothyronine deiodinases play important roles in coordinating development in Rana catesbeiana tadpoles.},
  author={K B Becker and K C Stephens and Jennifer C. Davey and M. J. Schneider and Valerie Anne Galton},
  journal={Endocrinology},
  year={1997},
  volume={138 7},
  pages={
          2989-97
        }
}
In developing Rana catesbeiana tadpoles, the timing of the thyroid hormone (TH)-dependent metamorphic responses varies markedly among tissues. Yet at any one time these tissues are exposed to the same plasma concentration of TH, suggesting that TH action is regulated in part at the level of the peripheral tissues. A major factor in TH action is the intracellular level of the active TH, T3. This level is dependent not only on the plasma concentration of TH (mostly T4) but also on the… 
Expression profiles of the three iodothyronine deiodinases, D1, D2, and D3, in the developing rat.
TLDR
The findings are consistent with the view that the deiodinases play a major role in achieving the intracellular T3 levels that are optimal for the development of each tissue.
Evidence for a role of the type III-iodothyronine deiodinase in the regulation of 3,5,3'-triiodothyronine content in the human central nervous system.
TLDR
D3 contributes to the local regulation of T3 content in the human CNS and is found in hippocampus and temporal cortex, lower levels being found in the thalamus, hypothalamus, midbrain cerebellum, parietal and frontal cortex, and brain stem.
Iodothyronine deiodinase structure and function: from ascidians to humans.
TLDR
Deiodinase-like sequences have been identified in the genome of non-deuterostome organisms, suggesting that deiodination of externally derived THs may even be functionally relevant in a wide variety of invertebrates.
Expression of type II iodothyronine deiodinase marks the time that a tissue responds to thyroid hormone-induced metamorphosis in Xenopus laevis.
TLDR
Exogenous T4 induces early DNA synthesis in brain, spinal cord, and limb buds as efficiently as T3, which contributes to the timing of metamorphic changes in these tissues.
Physiology and pathophysiology of type 3 deiodinase in humans.
  • Stephen A. Huang
  • Biology, Medicine
    Thyroid : official journal of the American Thyroid Association
  • 2005
TLDR
Type 3 iodothyronine deiodinase is the physiologic inactivator of thyroid hormones, but recent data indicate that postnatal expression can be reactivated in normal tissues during critical illness and other pathologic conditions.
Type 2 iodothyronine deiodinase is essential for thyroid hormone-dependent embryonic development and pigmentation in zebrafish.
TLDR
Data indicate that TH activation by D2 is essential for embryonic development and pigmentation in zebrafish.
Deiodinases: the balance of thyroid hormone: local impact of thyroid hormone inactivation.
TLDR
The intriguing evidence that D3 plays a pivotal role in defining local TH concentration in the developing fetus and in several conditions in adult life is summarized.
The deiodinase family: selenoenzymes regulating thyroid hormone availability and action
  • J. Köhrle
  • Biology, Medicine
    Cellular and Molecular Life Sciences CMLS
  • 2000
TLDR
Characterization of tissue-specific expression patterns indicates that these selenium-dependent enzymes exert tight control on local and systemic availability of active T3 and deiodinases are envisaged as guardians to the gate of thyroid hormone action mediated by T3 receptors.
The roles of the iodothyronine deiodinases in mammalian development.
  • V. Galton
  • Biology, Medicine
    Thyroid : official journal of the American Thyroid Association
  • 2005
TLDR
Information, both indirect and that obtained from a D3-deficient mouse model, strongly suggests that its presence in placenta, uterus and some fetal tissues are critical for limiting exposure of fetal tissues to inappropriate levels of TH.
Type II iodothyronine deiodinase is preferentially expressed in rainbow trout (oncorhynchus mykiss) liver and gonads *
TLDR
The results show that the structural characteristics of the D2 protein and gene have been highly conserved during evolution, and suggests that rtD2 may be a key factor regulating local supply of active T3 during rainbow trout gametogenesis.
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References

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Hepatic iodothyronine 5-deiodinase activity in Rana catesbeiana tadpoles at different stages of the life cycle.
TLDR
An alternative explanation for the failure to observe T4 to T3 conversion before climax is offered; in pre- and prometamorphic tadpoles, any T3 produced from T4 is rapidly converted to 3,3'-diiodothyronine by the 5 D system and thus accumulation is prevented.
Iodothyronine 5'-deiodinase activity in the amphibian Rana catesbeiana at different stages of the life cycle.
TLDR
It is indicated that gut and skin are the principal T3-generating organs in anuran amphibia and suggest that increased activity of the 5'D system, at the time in the life cycle that the tissues require increased amounts of thyroid hormone, is an important part of thyroid hormones economy in this species.
The type III 5-deiodinase in Rana catesbeiana tadpoles is encoded by a thyroid hormone-responsive gene.
TLDR
It is suggested that the 5D system plays a major role in regulating intracellular T3 levels in developing tadpoles.
A thyroid hormone-regulated gene in Xenopus laevis encodes a type III iodothyronine 5-deiodinase.
TLDR
It is reported here that the protein encoded by the XL-15 cDNA efficiently catalyzes the (inner ring) 5-deiodination of 3,5,3'-triiodothyronine with a Km value of 2 nM and is resistant to inhibition by propylthiouracil and aurothioglucose.
The role of 3,5,3'-triiodothyronine in the physiological action of thyroxine in the premetamorphic tadpole.
TLDR
Findings indicate that generation of T3 from T4 can take place in vivo in the premetamorphic tadpole and strongly support the hypothesis that this process plays an important role in the physiological action of T4 in this species.
Effect of glucocorticoids on thyroid hormone action in cultured red blood cells from Rana catesbeiana tadpoles.
TLDR
Findings indicate that B may be a physiological modulator of TH action in tadpole RBCs, which contrasts with previous reports that GC accelerates some of the morphological effects of TH in developing tadpoles.
The Role of Thyroid Hormone in Amphibian Development
TLDR
In vivo studies indicate that accumulation of 3,5,3′-triiodothyronine following administration of thyroxine (T4) is minimal until just prior to metamorphic climax, and in vitro studies of 5 D and 5′D activities suggest that this is due primarily to the presence in pre- and prometamorphic tadpole liver of an active 5 D system which rapidly converts any T3, present to 3, 3′-diiodothyRONine.
Regulation of c-erbA-α Messenger RNA Species in Tadpole Erythrocytes by Thyroid Hormone
TLDR
Putative thyroid hormone (TH) nuclear receptors have been detected in several tissues of Rana catesbeiana tadpoles and two c-erbA cDNAs were used to examine their role in the TH induction of tadpole RBC receptor number.
Increase in binding capacity for triiodothyronine in tadpole tail nuclei during metamorphosis
TLDR
Results suggest that in amphibians the maximum number of binding sites rather than the affinity constant correlate with the biological activity of T3 and T4, however, in mammals specific high-affinity binding sites for the thyroid hormones were found in nuclei6–8 and correlate withThe affinity constant.
The ontogeny of iodothyronine 5'-monodeiodinase activity in Rana catesbeiana tadpoles.
TLDR
It is suggested that accumulation of T3 generated from T4 in the tadpole is minimal before MD due to the predominance of 5D activity.
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