Inhibition of Thyroid Adenylate Cyclase by Thyroid Hormone: A Possible Locus for the “Short-Loop” Negative Feedback Phenomenon<sup>1</sup>

Friedman, Yochanan; Lang, Michael; Burke, Gerald

doi:10.1210/endo-101-3-858

Cited by 33 publications

(11 citation statements)

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“…Although Friedman et al (1977) have described the inhibition of thyroid adenylate cyclase by TH as a possible negative feedback mechanism, several evidences in the literature point to the ability of TH to increase cyclicAMP (cAMP) levels in other cell types (Leitman et al, 1996;Sarkar et al, 1999;Zamoner et al, 2006). In this context, our group demonstrated that TH modulate PKA-mediated IF phosphorylation in cerebral cortex (Zamoner et al, 2006), supporting the hypothesis that the increased GFAP phosphorylation we have observed could be through PKAdependent mechanisms.…”

Section: Fig 6 Effect Of Thyroid Hormones (T 3 and T 4 ) On The In supporting

confidence: 84%

Thyroid Hormones Reorganize the Cytoskeleton of Glial Cells Through Gfap Phosphorylation and Rhoa-Dependent Mechanisms

et al. 2007

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Thyroid hormones (3,5,3'-triiodo-L: -thyronine, T3; 3,5,3',5'-L: -tetraiodothyronine, T4; TH) play crucial roles in the growth and differentiation of the central nervous system. In this study, we investigated the actions of TH on proliferation, viability, cell morphology, in vitro phosphorylation of glial fibrillary acidic protein (GFAP) and actin reorganization in C6 glioma cells. We first observe that long-term exposure to TH stimulates cell proliferation without induce cell death. We also demonstrate that after 3, 6, 12, 18, and 24 h treatment with TH, C6 cells and cortical astrocytes show a process-bearing shape. Furthermore, immunocytochemistry with anti-actin and anti-GFAP antibodies reveals that TH induces reorganization of actin and GFAP cytoskeleton. We also observe an increased in vitro 32P incorporation into GFAP recovered into the high-salt Triton insoluble cytoskeletal fraction after 3 and 24 h exposure to 5 x 10(-8) and 10(-6) M T3, and only after 24 h exposure to 10(-9) M T4. These results show a T3 action on the phosphorylating system associated to GFAP and suggest a T3-independent effect of T4 on this cytoskeletal protein. In addition, C6 cells and astrocytes treated with lysophosphatidic acid, an upstream activator of the RhoA GTPase pathway, totally prevented the morphological alterations induced by TH, indicating that this effect could be mediated by the RhoA signaling pathway. Considering that IF network can be regulated by phosphorylation leading to reorganization of IF filamentous structure and that alterations of the microfilament organization may have important implications in glial functions, the effects of TH on glial cell cytoskeleton could be implicated in essential neural events such as brain development.

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Section: Fig 6 Effect Of Thyroid Hormones (T 3 and T 4 ) On The In supporting

confidence: 84%

Thyroid Hormones Reorganize the Cytoskeleton of Glial Cells Through Gfap Phosphorylation and Rhoa-Dependent Mechanisms

et al. 2007

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“…Release of T4, T3, or iodide induced by TSH might contribute to the refractoriness related to organification of iodide. Such a short-loop feedback system has been reported both in vivo and in vitro (13)(14)(15) but has also been denied in vivo (16). In the present experiments, thyroid hormones did not diminish the TSH stimulation of organification of iodide (Fig.…”

Section: Resultssupporting

confidence: 61%

In Vitro and In Vivo Refractoriness to Thyrotropin Stimulation of Iodine Organification and Thyroid Hormone Secretion

Field¹,

Dekker²,

Titus³

et al. 1979

J. Clin. Invest.

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A B S T R A C T Earlier studies indicated that initial exposure of thyroid slices to thyrotropin diminished responsiveness of the adenylate cyclase-cyclic AMP system, glucose oxidation, and 32Pi incorporation into phospholipids upon readdition of the hormone. The present studies demonstrate that slices from dog, beef, and human thyroid glands initially incubated with thyrotropin (TSH) were less responsive to subsequent addition of the hormone when organification of iodide was examined. Increasing the amount of TSH did not overcome the refractoriness induced by the initial exposure to the hormone. Furthermore, the stimulatory effects of dibutyryl cyclic AMP and prostagladin E1 were abolished in slices previously incubated with TSH. Development of such refractoriness did not depend upon new protein synthesis and was not abolished by 1 mM prophylthiouracil in the first incubation. Addition of 0.1 ,uM thyroxine or triiodothyronine or 1.5 ,M iodide during all three incubations did not modify the response to TSH, added for the first time in the third incubation. However, 1 mM iodide in the buffer during all three incubations inhibited the response to TSH during the third incubation. During the refractory period, effects of TSH on colloid droplet formation were also diminished. The in vivo effect of TSH on serum 1-triiodothyronine in rats was significantly reduced when the rats had been injected with TSH 8 h earlier. These studies demonstrate that TSH-induced refractoriness also includes effects on organification of iodine and secretion of thyroid hormone. The results cannot be adequately explained by unresponsiveness of adenylate cyclase because effects of dibutyryl cyclic AMP and prostagladin E1 were also inhibited by prior exposure to TSH.

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“…The thyroid hormones have been shown to exert a short-loop feed-back-like inhibition of TSH activity (44) in a manner much resembling that described for T g (9). The intrinsic content of iodothyronines of Tg, especially thyroxine and triiodothyronine, might therefore be suspected responsible for the inhibition of the adenylate cyclase activity of the thyroid membrane.…”

Section: Role Of Thyroglobulin In the Regulation Of Thyroid Functionmentioning

confidence: 77%

Serum Thyroglobulin and Thyroglobulin Autoantibodies in Thyroid Diseases

Feldt‐Rasmussen

1983

Allergy

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Inhibition of Thyroid Adenylate Cyclase by Thyroid Hormone: A Possible Locus for the “Short-Loop” Negative Feedback Phenomenon¹

Cited by 33 publications

References 0 publications

Thyroid Hormones Reorganize the Cytoskeleton of Glial Cells Through Gfap Phosphorylation and Rhoa-Dependent Mechanisms

Thyroid Hormones Reorganize the Cytoskeleton of Glial Cells Through Gfap Phosphorylation and Rhoa-Dependent Mechanisms

In Vitro and In Vivo Refractoriness to Thyrotropin Stimulation of Iodine Organification and Thyroid Hormone Secretion

Serum Thyroglobulin and Thyroglobulin Autoantibodies in Thyroid Diseases

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Inhibition of Thyroid Adenylate Cyclase by Thyroid Hormone: A Possible Locus for the “Short-Loop” Negative Feedback Phenomenon1

Cited by 33 publications

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Thyroid Hormones Reorganize the Cytoskeleton of Glial Cells Through Gfap Phosphorylation and Rhoa-Dependent Mechanisms

Thyroid Hormones Reorganize the Cytoskeleton of Glial Cells Through Gfap Phosphorylation and Rhoa-Dependent Mechanisms

In Vitro and In Vivo Refractoriness to Thyrotropin Stimulation of Iodine Organification and Thyroid Hormone Secretion

Serum Thyroglobulin and Thyroglobulin Autoantibodies in Thyroid Diseases

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Inhibition of Thyroid Adenylate Cyclase by Thyroid Hormone: A Possible Locus for the “Short-Loop” Negative Feedback Phenomenon¹