Mouse Thyroid Research Articles

Antioxidant Potential of Parsley Leaf (Petroselinum crispum) Essential Oil on Hypothyroidism and Testicular Injury in Mice Intoxicated by Carbon Tetrachloride.

The aim of the present study was to investigate the ameliorative potential of parsley (Petroselinum crispum) leaf essential oil (PO) against the detrimental effects of carbon tetrachloride (CCl4) on the thyroid gland and testes of mice. Twenty-four adult male mice were divided into four groups and treated for 4 weeks. The 1st control group received 3 mL/kg olive oil intraperitoneally, twice a week followed by 0.5 mL/kg saline intragastrically daily. The 2nd CCl4 group received CCl4 (3 mL/kg intraperitoneally, twice a week). The 3rd PO group received PO (0.5 mL/kg intragastrically daily), while the 4th CCl4+PO group received CCl4 coadministrated with PO at the aforementioned doses. CCl4 group recorded significant (p < 0.05) reduction in the activities of antioxidant enzyme catalase (CAT) and superoxide dismutase (SOD) and significant (p < 0.05) increase in the lipid peroxidation end product's level malondialdehyde (MDA) in the testes and thyroid glands. Meanwhile, serum levels of testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid hormones (thyroid-stimulating hormone (TSH), total triiodothyronine (T3), free triiodothyronine (fT3), total thyroxine (T4), and free thyroxine (fT4)) significantly decreased. Also, histopathologically, the testicular tissue showed hypospermatogenesis within irregular-shaped seminiferous tubules with prominent edema in the interstitial spaces confirming the aforementioned biochemical alterations. Treatment with PO significantly reduced the testicular and thyroid oxidative stress (p < 0.05) and elevated the testosterone (73.47%), FSH (92.11%), LH (33.33%), T3 (23.47%), fT3 (39.13%), T4 (27.91%), and fT4 (75%) as compared to that of CCl4-treated group corresponding values. The PO GC/MS analysis indicated bioactive monoterpenes (major component is 1,3,8-mentha triene 34.48%) and phenylpropenes (major component is myristicin 21.04%). Results suggested the ameliorative effect of PO against CCl4-induced hypogonadism in mice by suppressing oxidative stress and maintaining thyroid gland function.

Thyroid hormone receptor β sumoylation is required for thyrotropin regulation and thyroid hormone production.

Thyroid hormone receptor β (THRB) is posttranslationally modified by small ubiquitin-like modifier (SUMO). We generated a mouse model with a mutation that disrupted sumoylation at lysine 146 (K146Q) and resulted in desumoylated THRB as the predominant form in tissues. The THRB K146Q mutant mice had normal serum thyroxine (T4), markedly elevated serum thyrotropin-stimulating hormone (TSH; 81-fold above control), and enlargement of both the pituitary and the thyroid gland. The marked elevation in TSH, despite a normal serum T4, indicated blunted feedback regulation of TSH. The THRB K146Q mutation altered the recruitment of transcription factors to the TSHβ gene promoter, compared with WT, in hyperthyroidism and hypothyroidism. Thyroid hormone content (T4, T3, and rT3) in the thyroid gland of the THRB K146Q mice was 10-fold lower (per gram tissue) than control, despite normal TSH bioactivity. The expression of thyroglobulin and dual oxidase 2 genes in the thyroid was reduced and associated with modifications of cAMP response element–binding protein DNA binding and cofactor interactions in the presence of the desumoylated THRB. Therefore, thyroid hormone production had both TSH-dependent and TSH-independent components. We conclude that THRB sumoylation at K146 was required for normal TSH feedback regulation and TH synthesis in the thyroid gland, by a TSH-independent pathway.

Presence of TSHR in NK Cells and Action of TSH on NK Cells

Introduction: Thyroid-stimulating hormone receptor (TSHR) is widely expressed in human tissues and cells. TSHR is not only involved in thyroid disease but also in the neuroendocrine-immune regulatory network. However, no study has exclusively focused on the expression and function of TSHR in natural killer (NK) cells. Methods: We studied TSHR expression using reverse transcription PCR to verify TSHR mRNA transcripts in human and mouse NK cells. Human and mouse thyroid and liver tissues as well as peripheral blood mononuclear cells (PBMCs) or spleen lymphoid cells (SLCs) were used as controls. The TSHR protein levels in NK-92 cells were determined by immunofluorescence staining. The function of TSHR in NK cells was investigated by measuring the TSH-stimulated cAMP levels. Results: TSHR mRNA was detected in human and mouse NK cells as well as in NK-92 cells and had the same sequence as that of thyroid-derived, PBMC-derived, and liver-derived mRNA. The TSHR protein was also expressed in the cell membrane of NK-92 cells. Furthermore, the cAMP levels in NK-92 cells were significantly higher after adding 10² mIU/mL of bovine TSH at p < 0.05, which stimulated cAMP production in NK-92 cells. Conclusions: Our findings confirm that TSHR is present and functional in NK cells and provide key clues for the potential regulatory effects of TSH on TSHR in NK cells in the immune system.

Abstract 2661: Role of NKX2-1 in thyroid neoplasms induced by iodine-deficiency and radiation

Abstract The multi-step carcinogenesis model, including the adenoma-carcinoma sequence, has been proposed in many cancers including those of colon, pancreas, and thyroid. BRAF activation is among the reported gene mutations important for thyroid carcinogenesis. However, the role of NKX2-1, a master regulator of thyroid development and function, in thyroid carcinogenesis remains elusive. In this study, we investigated the role of NKX2-1 in thyroid neoplasm formation using thyroid-specific Nkx2-1 conditional KO mice, Nkx2-1(fl/fl);TPO-Cre (cKO mice). Nkx2-1(fl/fl) (WT) and cKO mice were each allotted to four groups: 1. Control Diet, 2. Control Diet + Radiation, 3. Low Iodine Diet (LID), 4. LID + Radiation. Whole body gamma-irradiation (2 Gy, 3 times every other day) was carried out at 4-8 weeks of age, followed by switching the diet to either Control Diet or LID. Thyroid histology was examined at 1.1-1.3 years after the start of the diet. In both WT and cKO mice, iodine-deficiency, regardless of radiation, induced diffuse hyperplasia (goiter) in more than 50% of the mice, and increased the incidence of focal hyperplasia considered as a preneoplastic lesion. Adenoma formation was only observed in LID-treated mice regardless of radiation, suggesting that iodine-deficiency, but not radiation, is a key factor for mouse thyroid adenoma formation. The incidence of adenoma formation was significantly higher in cKO mice than WT mice in LID + Radiation group (14% for WT vs 52% for cKO, in progress). In addition, carcinoma formation was observed only in LID + Radiation-treated mice, suggesting that radiation is necessary to proceed from adenoma to cancer in thyroid carcinogenesis. Further, there is a tendency for higher incidence of carcinoma in LID + Radiation-treated cKO mice (4% for WT vs 11% for cKO, in progress). These results suggest that the loss of Nkx2-1 can promote adenoma formation induced by iodine-deficiency, and possibly facilitate carcinogenesis induced by LID + Radiation. In summary, our results suggest that NKX2-1 may function as a tumor suppressor in thyroid carcinogenesis. We are now trying to investigate the molecular mechanisms by which loss of NKX2-1 affects thyroid proliferation and facilitates neoplasm formation by examining the molecular profiles of mouse thyroids after LID and/or radiation treatment. Citation Format: Yo-Taro Shirai, Yoshinori Takizawa, Manabu Iwadate, Jorge Paiz, Shigetoshi Yokoyama, Masaaki Miyakoshi, Jerrold M. Ward, Shioko Kimura. Role of NKX2-1 in thyroid neoplasms induced by iodine-deficiency and radiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2661.

Effect of Pesticide Indoxacarb on the Thyroid Gland in Swiss Albino Mice

Background and objectives: Pesticides play an essential role in crop protection, but their overuse caused environmental pollution and harmful effect on different animal body systems, including the endocrine system. The thyroid gland is one of the homeostatic regulators of metabolic activities, which is affected by the elements of the external environment. There are very limited studies on the effect of indoxacarb on the histological architecture and functions of thyroid gland. Therefore, this study was conducted with the aim of examining functionally and histologically of the thyroid gland exposed to indoxacarb. Method: 24 Swiss albino mice male and female were randomly divided into two groups, each group male and female; group I is a control group given orally with 1ml of distilled water and group II orally treated with 120 mg/kg Bw. of indoxacarb daily for 3 weeks. Blood samples were collected from each mouse under anesthetic to determine the thyroid-stimulating hormone (TSH), thyroxine (T4) levels. Thyroid gland histopathology was attained for the evaluation of the indoxacarb effect. Results: The treated mice showed non-significant increase in T4 levels and a significant decrease in TSH levels but there was no significant difference recorded in T4 and TSH levels between sexes. Histologically, the sections of the thyroid gland of the treated group showed empty and irregular follicles, degeneration of the follicular epithelial tissue, and hyperplasia in the lining of some follicles, the capsule with congestion blood vessels. Conclusion: This study concluded that indoxacarb may act as a thyroid gland toxicant.

Organic iodine-based preparation inhibits growth of B16/F10 melanoma in C57BL6 mice with thyroid disorders.

e21580 Background: The thyroid gland is the most important regulator of the body's response to stressful influences, including malignant growth. Iodine is a constituent of thyroid hormones, and it plays an important role in anti-tumor protection. The purpose of the study was to analyze the levels of thyroid hormones in the thyroid gland of male and female mice with B16/F10 melanoma, as well as the effect of an organic iodine-based preparation on the survival of animals with transplanted melanoma. Methods: Levels of total (T3, T4) and free (FT3, FT4) thyroid hormones were measured by RIA in the thyroid of male and female С57ВL/6 mice (n = 80) with transplantable B16/F10 melanoma. The effect of an organic iodine-based preparation on the dynamics of the melanoma growth was studied in the main group of animals (n = 42) receiving per os 1,3-diethylbenzimidazolium triiodide in a single dose of 0.4 mg/kg throughout the experiment; the control group (n = 20) received distilled water. The tumor volume and survival of mice were measured. Results: The lowT3/lowT4 syndrome developed in females with transplantable B16/F10 melanoma starting from week 2 of the experiment, diagnosed by decreasing levels of FТ3 and FТ4 by 3 times and lower and normal levels of T3 and T4. In males, melanoma growth caused the thyroid hypofunction expressed in a decrease in the levels of T3 and T4 by 2 times, and FT3 and FT4 by 1.5 times. The latent period prior to the tumor onset was 10-12 days in females and 5-7 days in males. The survival of females was 5-6 weeks, males – 3-4 weeks. The administration of the organic iodine-based preparation extended the latent period in females up to 14-18 days, in males up to 10-14 days; the survival of females increased by 1.8 times, males by 1.5 times. 9% of females in the main group showed complete tumor resorption without relapses throughout their lives. Conclusions: The growth of transplantable B16/F10 melanoma in male and female С57ВL/6 mice was accompanied by suppression of the thyroid function with the development of uncontrolled hypothyroidism in males and the lowT3/lowT4 syndrome in females, which correlates with the survival of animals.

The Association of Myo-Inositol and Selenium Contrasts Cadmium-Induced Thyroid C Cell Hyperplasia and Hypertrophy in Mice.

Previous studies have demonstrated that, in addition to inducing structural changes in thyroid follicles, cadmium (Cd) increased the number of C cells. We examined the effects of myo-inositol (MI), seleno-L-methionine (Se), MI + Se, and resveratrol on C cells of mice exposed to cadmium chloride (Cd Cl2), as no data are currently available on the possible protective effects of these molecules. In contrast, we have previously shown this protective effect against CdCl2 on the thyroid follicles of mice. Ninety-eight C57 BL/6J adult male mice were divided into 14 groups of seven mice each: (i) 0.9% NaCl (vehicle; 1 ml/kg/day i.p.); (ii) Se (0.2 mg/kg/day per os); (iii) Se (0.4 mg/kg/day per os); (iv) MI (360 mg/kg/day per os); (v) Se (0.2 mg/kg/day) + MI; (vi) Se (0.4 mg/kg/day) + MI; (vii) resveratrol (20 mg/kg); (viii) CdCl2 (2 mg/kg/day i.p.) + vehicle; (ix) CdCl2 + Se (0.2 mg/kg/day); (x) CdCl2 + Se (0.4 mg/kg/day); (xi) CdCl2 + MI; (xii) CdCl2 + Se (0.2 mg/kg/day) + MI; (xiii) CdCl2 + Se (0.4 mg/kg/day) + MI; (xiv) CdCl2 + resveratrol (20 mg/kg). After 14 days, thyroids were processed for histological, immunohistochemical, and morphometric evaluation. Compared to vehicle, Cd significantly decreased follicle mean diameter, increased CT-positive cells number, area and cytoplasmic density, and caused the disappearance of TUNEL-positive C cells, namely, the disappearance of C cells undergoing apoptosis. Se at either 0.2 or 0.4 mg/kg/day failed to significantly increase follicular mean diameter, mildly decreased CT-positive cells number, area and cytoplasmic density, and was ineffective on TUNEL-positive C cells. Instead, MI alone increased significantly follicular mean diameter and TUNEL-positive cells number, and decreased significantly CT-positive cells number, area and cytoplasmic density. MI + Se 0.2 mg/kg/day or MI + Se 0.4 mg/kg/day administration improved all five indices more markedly. Indeed, follicular mean diameter and TUNEL-positive cells number increased significantly, while CT-positive cells number, area and cytoplasmic density decreased significantly. Thus, all five indices overlapped those observed in vehicle-treated mice. Resveratrol improved significantly all the considered parameters, with a magnitude comparable to that of MI alone. In conclusion, the association Myo + Se is effective in protecting the mouse thyroid from the Cd-induced hyperplasia and hypertrophy of C cells. This benefit adds to that exerted by Myo + Se on thyrocytes and testis.

A Stem Cell Surge During Thyroid Regeneration.

BackgroundMany tissues, including the thyroid, contain resident (adult) stem cells that are responsible for regeneration and repair after injury. The mechanisms of thyroid regeneration and the role of thyroid stem cells and thyroid progenitor cells in this process are not well understood. We have now used a new mouse thyroid injury model to gain insight into this phenomenon.MethodsTamoxifen induced TPO-Cre mice (TPOCreER2) were crossed with inducible Diphtheria Toxin Receptor homozygous mice (ROSA26iDTR) to give rise to TPOCreER2/iDTR mice, allowing for the Cre-mediated expression of the DTR and rendering TPO expressing thyroid cells highly sensitive to diphtheria toxin (DT). This model of TPOCreER2/iDTR mice allowed us to study the repair/regeneration of thyroid follicles after diphtheria toxin induced thyroid damage by measuring serum thyroid hormones and cell fate.ResultsIn TPOCreER2/iDTR double transgenic mice we observed severe thyroid damage as early as 2 weeks after initiating intraperitoneal DT injections. There was marked thyroid tissue apoptosis and a ~50% drop in serum T4 levels (from 5.86 to 2.43 ug/dl) and a corresponding increase in serum TSH (from 0.18 to 8.39 ng/dl). In addition, there was a ~50% decrease in transcription of thyroid specific genes (thyroglobulin, TSH receptor, and sodium-iodide symporter). After suspending the DT administration, the thyroid rapidly recovered over a 4-week period during which we observed a transient surge in stem cell marker expression (including Oct4, Nanog, Sox2, and Rex1). In addition, cells immunostaining with stem cell markers Oct4 and Ssea-1 were found in clusters around new thyroid follicles in TPOCreER2/iDTR double transgenic mice. Furthermore, the presence of clusters of thyroid progenitor cells was also identified by Pax8 staining of thyroglobulin negative cells. This recovery of the injured gland was followed by a rapid and sequential restoration of thyroid function.ConclusionThese data demonstrate that a new model of thyroid cell damage induced by DT can be used to study the mobilization of resident adult stem cells. Furthermore, the model clearly demonstrates the involvement of both stem and progenitor cells in the in vivo regeneration of the thyroid after severe destruction.

МОРФОСТРУКТУРА ЩИТОВИДНОЙ ЖЕЛЕЗЫ МЫШИ ПОЛЕВОЙ В НОРМЕ В УСЛОВИЯХ КРАСНОЯРСКОЙ ЛЕСОСТЕПИ

The regional research of the zonal undisturbed (normal) morphology of the thyroid gland of young field mice was carried out in the conditions of forest-steppe near Krasnoyarsk. The most important indicators of the thyroid gland are identified: macroscopically, the width of each lobe is 2-2. 7 mm, the length is 1.5-2 mm, the height is 1-2 mm. The width of the isthmus is 1.5-2 mm. The color of the gland ranges from red to dark red and it clearly contrasts with the background of the larynx and thyroid cartilage. The thyroid and parathyroid glands are a single organocomplex. The specific features of the structure of the thyroid gland of field mice are the small size of the organ, a thin capsule, the presence of internal accessory parathyroid glands, a compactly organized parenchyma, and a moderately developed vascular network. The stroma of the gland is relatively poorly developed, it contains a thin network of reticular cells, a small number of macrophages. The epithelium of large follicles has a prismatic shape, although middle size follicles have cubic shaped epithelium. The height of thyrocytes is 6.83 microns, the mean area of follicles is 467.9 microns; Brown index is 9.7; follicular-colloid index is 3.72; the sclerosis index is 0.81. The field mouse, due to its ecological and morphological features, is a valuable object of bioindication for assessment of the state of background and anthropogenic landscape in the conditions of the Krasnoyarsk forest-steppe. The size of the gland (taking into account age of a mouse), the Brown index, as well as the height and shape of thyrocytes (follicular epithelium) are significant bioindication criteria to assess the changes in the case of technogenic exposure influenced by pollutants.

Mice Hypomorphic for Keap1, a Negative Regulator of the Nrf2 Antioxidant Response, Show Age-Dependent Diffuse Goiter with Elevated Thyrotropin Levels.

Background: Familial nontoxic multinodular goiter (MNG) is a rare disease. One of the associated genes is Kelch-like ECH-associated protein 1 (KEAP1), which encodes the main inhibitor of nuclear factor erythroid 2-related transcription factor 2 (Nrf2), a central mediator of antioxidant responses. The association of KEAP1 with familial MNG is based on only two loss-of-function mutations identified in two families, only one of which included proper phenotyping and adequate demonstration of co-segregation of the phenotype and the mutation. There is no experimental evidence from model organisms to support that decreased Keap1 levels can, indeed, cause goiter. This study used mice hypomorphic for Keap1 to test whether decreased Keap1 expression can cause goiter, and to characterize the activation status of Nrf2 in their thyroid.Methods: C57BL/6J Keap1flox/flox (Keap1 knock-down [Keap1KD]) mice were studied at 3 and 12 months of age. Plasma and thyroid glands were harvested for evaluation of thyroid function tests and for gene and protein expression by real-time polymerase chain reaction and immunoblotting, respectively.Results: Keap1KD mice showed diffuse goiter that began to develop in early adult life and became highly prominent and penetrant with age. The goiter was characterized by a markedly increased size of thyroid follicles, most notably of the colloid compartment, and by absence of thyroid nodules or hyperplasia. Keap1KD mice also showed decreased T4 levels in early adult life that were eventually well compensated over time by increased thyrotropin (TSH) levels. Nrf2 was activated in the thyroid of Keap1KD mice. Despite a known stimulatory effect of Nrf2 on thyroglobulin (Tg) gene transcription and Tg protein abundance, the expression levels were decreased in the thyroid of Keap1KD mice. No clear patterns were observed in the expression profiles of other thyroid hormone synthesis-specific factors, with the exception of Tg-processing and Tg-degrading cathepsins, including an increase in mature forms of cathepsins D, L, and S.Conclusions: Keap1KD mice develop age-dependent diffuse goiter with elevated TSH levels. The precise mechanism accounting for the thyroidal phenotype remains to be elucidated, but it may involve enhanced Tg solubilization and excessive lysosomal Tg degradation.

Transcriptomic response of mouse thyroid to iodine by upregulating Nrf2-dependent and independent pathways

Transcriptomic response of mouse thyroid to iodine by upregulating Nrf2-dependent and independent pathways

EXIRAD-3D: Fast automated three-dimensional autoradiography

IntroductionAutoradiography is an established technique for high-resolution imaging of radiolabelled molecules in biological tissue slices. Unfortunately, creating a 3D image from a set of these 2D images is extremely time-consuming and error-prone. MicroSPECT systems provide such 3D images but have a low resolution. Here we present EXIRAD-3D, a fast automated method as an alternative for 3D autoradiography from coupes based on ultra-high resolution microSPECT technology. MethodsEXIRAD-3D uses a very small bore focusing multi-pinhole collimator mounted in a SPECT system with stationary detectors (U-SPECT/CT, MILabs B.V. The Netherlands) using a sample holder with integrated tissue cooling to avoid activity leaking or tissue deformation during the scan. The system performance was experimentally evaluated using various phantoms and tissue samples of animals in vivo injected with technetium-99m and iodine-123. ResultsThe reconstructed spatial resolution obtained with a Derenzo hot rod phantom was 120 μm (or 1.7 nl). The voxel values of a syringe phantom image appear to be uniform and scale linearly with activity. Uptake in tiny details of the mouse knee joint, thyroid, and kidney could be clearly visualized. ConclusionEXIRAD-3D opens up the possibility for fast and quantitative 3D imaging of radiolabelled molecules at a resolution far better than in vivo microSPECT and saves tremendous amounts of work compared to obtaining 3D data from a set of 2D autoradiographs. Advances in knowledge and implications for patient careEXIRAD-3D offers superior image resolution over microSPECT, and it can be a very efficient alternative for autoradiography in pharmaceutical and biological studies.

Therapeutic Role of Mitochondria Targeted Curcumin against Pseudomonas aeruginosa Induced Oxidative Stress in Thyroid Gland of Female Swiss albino Mice

Bacteria are found universally and contaminate the soil, air and water. Through contaminated air, water and soil bacteria reach inside the body and causes immense harm. The problem of thyroid is that, it affects the public health worldwide. The main purpose of this investigation is to find out the toxic effects of Pseudomonas aeruginosa on thyroid gland and preventive role of mitochondria targeted curcumin in bacterial induced thyroid toxicity in female Swiss albino mice. The animals are separated in different groups. Group I served as control and Group II administered with effective dose of Pseudomonas aeruginosa . Group III co-treated with mitochondria targeted curcumin for the period of 14 days. With the completion of treatment period blood serum and tissue samples were collected for determining the level of thyroid hormones and oxidative stress. In this investigation shows that mice exposed to bacteria have decreased T3 and T4 concentration as compared to control and co-treated mice have some elevated level of T3 and T4 hormones as compared to bacteria treated mice. In the biochemical study it is found that the increased lactate dehydrogenate, catalase activity, superoxide dismutase and lipid peroxidation and decreased glutathione reductase points towards the induced oxidative stress in thyroid gland. It is concluded that the exposure to Pseudomonas aeruginosa causes thyroid problem and treatment with mitochondria targeted curcumin prevents the induced toxicity.

Experimental evidence for alpha enolase as one potential autoantigen in the pathogenesis of both autoimmune thyroiditis and its related encephalopathy

Alpha-enolase (ENO1) is a ubiquitous protein. Patients with autoimmune thyroiditis-associated encephalopathy have high serum ENO1Ab titers. We aimed to explore whether ENO1Ab was the pathogenic antibody in the thyroid and brain. The serum ENO1Ab titers were significantly increased in the mice immunized with Thyroglobulin (Tg). And in the mice immunized with ENO1, serum levels of both TgAb and thyroid-stimulating hormone (TSH) were significantly increased. Obvious CD16+ cell infiltration, IgG deposit and cleaved caspase-3 were observed in the thyroid of ENO1-immunized mice. Spatial learning and memory abilities and synaptic functions were impaired in ENO1-immunized mice. Furthermore, the expression levels of Iba-1, GFAP, interlukin-6, CDK5, and phosphorylated tau were increased, and endothelial tight junction proteins were decreased in the brain of ENO1-immunized mice. These results suggest that ENO1Ab can cause thyrocyte damage via ADCC effect and impair cerebral function by disrupting the blood–brain barrier.

Hormonal Regulation of Autophagy in Thyroid PCCL3 Cells and the Thyroids of Male Mice.

Autophagy is an evolutionarily conserved catabolic process by which cells degrade intracellular proteins and organelles in the lysosomes and recycle their metabolites. We have recently demonstrated the crucial role for the basal level of autophagic activity in thyrocyte survival and homeostasis using the thyroid-specific autophagy knockout mice. Here, we first studied hormonal regulation of autophagy in thyrocytes in vitro using a rat thyroid cell line PCCl3 and in vivo with mice. In cultured PCCl3 cells, thyroxine decreased microtubule-associated protein 1 light chain 3 (LC3) puncta (a component of autophagosome) and increased p62 (an autophagy substrate) levels, showing thyroxine-suppression of autophagy. In contrast, TSH increased both LC3 puncta and p62 levels, but at the same time stabilized p62 protein by inhibiting p62 degradation, indicating TSH induction of autophagy. Our experiments with various inhibitors identified that both the cAMP-protein kinase (PK) A-cAMP response element binding protein/ERK and PKC signaling pathways regulates positively autophagic activity. The in vivo results obtained with wild-type mice treated with methimazole and perchlorate or thyroxine were consistent with in vitro results. Next, in thyroid-specific autophagy knockout mice treated with methimazole and perchlorate (that is, mice were placed under a stressed condition where enhanced autophagy was required) for 2 months, lower follicle sizes and lower thyroglobulin contents in thyrocytes were observed, suggesting impaired thyroglobulin production presumably from insufficient nutrient supply. We therefore conclude that TSH positively regulates autophagic activity through the cAMP-PKA-cAMP response element binding protein/ERK and PKC signaling pathways, whereas thyroid hormones inhibit its activity in thyrocytes. Metabolites produced by autophagy appear to be necessary for protein synthesis stimulated by TSH.

OR28-01 Constitutive Activation of NRF2 Antioxidant Response Leads to Age-Dependent Goiter and Compensated Hypothyroidism in Male Mice

Background: Familial non-toxic multinodular goiter (MNG) is a rare disease. KEAP1 gene (Kelch-like ECH-associated protein 1) that encodes the main inhibitor of nuclear factor erythroid 2-related transcription factor 2 (Nrf2), a central mediator of antioxidant responses, has been found to be one of the mutated genes that lead to familial MNG. The proposed association of KEAP1 with familial MNG is based on only two loss-of-function mutations in respective Japanese families, only one of which included proper phenotyping and demonstration of co-segregation of phenotype and mutation. To date, there is no experimental evidence from model organisms to support that decreased Keap1 levels can cause goiter. Hypothesis: We hypothesized that enhanced Nrf2 signaling induced by loss of Keap1 function in mice can lead to goiter. Methods: To this end, male Keap1 hypomorphic C57BL/6J mice that express ~80% less Keap1 in their tissues (Keap1 knockdown mice:“Keap1KD”) were studied at 3 and 12 months of age and compared to wild-type mice (WT). Plasma, thyroids and pituitary glands were collected for assessment of thyroid function by radioimmunoassays and for histology as well as gene and protein expression by quantitative PCR and immunoblotting respectively. Results: Keap1KD showed diffuse goiter that began to develop in early adult life and became highly prominent at the age of 12 months when the thyroids of Keap1KD were 6-fold heavier than WT. Histomorphometry assessment of thyroids showed that Keap1KD had ~3-fold larger follicle area and colloid compartment but no thyroid nodules or hyperplasia was detected. Keap1KD also showed primary hypothyroidism already in early adult life that was eventually well-compensated over time by increased TSH levels (at age of 12 months: WT TSH=47.7±9.1 mU/L, Keap1KD TSH=460±74 mU/L). This was also reflected in the pituitary gland of Keap1KD where Tshb mRNA was ~3-fold higher than WT. Despite a known stimulatory effect of Nrf2 on Tg gene transcription and Tg protein abundance, these measures were decreased in the thyroid of Keap1KD mice. No clear patterns were observed in the expression profiles of other thyroid hormone synthesis-specific factors, such as Duox1, Duoxa1, Duox2, Duoxa2, Tpo, Nis, Dio1, Dio2, Dehal1 mRNA levels, with the exception of Tg-processing and Tg-degrading cathepsins, including an increase in mature forms of cathepsins D, L and S. Conclusions: Keap1KD mice showed age-dependent diffuse goiter and compensated hypothyroidism. The precise mechanism accounting for the thyroidal phenotype remains to be elucidated, but it may involve enhanced Tg solubilization and excessive lysosomal Tg degradation. This study unravels novel roles of the druggable Keap1/Nrf2 pathway in thyroid function and economy. Subclinical hypothyroidism in Keap1KD mice may have broader implications regarding their use in metabolic research.

SAT-455 Mouse Thyroid Responds to Iodine Overload by Transcriptionally Enhancing the Keap1/Nrf2 Antioxidant Response and by Upregulating Nrf2-Dependent and Independent Inflammatory and Fibrosis Pathways

Nrf2 (Nfe2l2) is a transcription factor that regulates a series of cytoprotective and antioxidant enzymes. Its cytoplasmic inhibitor Keap1 senses the presence of oxidative or electrophilic stress though the interaction of sulfhydryl groups of its cysteines with reactive species and ceases to bind Nrf2. Thus, Nrf2 can transfer to the nucleus and induce its target genes. Follicular thyroid cells have physiologically high levels of reactive oxygen species as oxidation of iodine is essential for iodination of thyroglobulin and thyroid hormones synthesis. We have shown previously that Nrf2 pathway is active in thyroid and regulates the transcription of thyroglobulin. We thus hypothesized that the response of thyroid to iodine excess should comprise Nrf2-dependent and -independent pathways. To this end, 3 months-old male C57Bl6J WT or Nrf2 knockout (KO) mice were exposed to 0.05% sodium iodide in their water for 7 days. Thyroids were excised and used for RNA extraction; RNA-seq was performed by Exiqon, with a fold-change cutoff set at 2. Selected representative genes of the enriched pathways were quantified by real-time qPCR to validate RNA-seq results. Pathway analysis of the differentially expressed genes was performed using the Ingenuity Pathway Analysis (IPA) software. Pathways that were enriched with a p-value<0.05 were considered significant. 828 genes were differentially expressed in response to iodine exposure; 66% were upregulated, as were most of the highly enriched pathways (related to inflammatory-immune response, antioxidant response, xenobiotic metabolism, platelet activation and calcium signaling). About 300 genes were differentially expressed between WT and KO mice; highly enriched pathways were related to glutathione and xenobiotic metabolism, Ahr signaling and Nrf2 signaling and were all downregulated in KO mice. Analysis of the potential upstream regulators of these highly enriched pathways revealed that Nrf2 and NfkB are major regulators of the antioxidant and inflammatory response induction upon iodine exposure and that Tgfβ-Smad cascade regulates the induction of fibrosis signaling. Last, we performed an analysis limited to already known thyroid pathways. A few genes were enriched following this method; upregulation of Duoxa1 (hydrogen peroxide generator) and downregulation of Nis (sodium iodide symporter) upon iodine exposure, which are expected responses, and the downregulation of thyroglobulin and upregulation of Duoxa1 in KO mice that confirm our previous findings. In conclusion, Nrf2-driven cytoprotective response is upregulated after iodine overload along with induction of inflammatory pathways. Nrf2 regulates transcriptomic responses in the thyroid, including a small but significant part of the response to iodine challenge. Hence, Nrf2 can be considered a novel player in the frontiers of thyroid antioxidant response and thyroid economy.

Bioinformatics Analysis and High-Throughput Sequencing to Identify Differentially Expressed Genes in Nebulin Gene (NEB) Mutations Mice.

BackgroundHigh-throughput sequencing of the pathological tissue of 59 patients with thyroid cancer was compared with the normal population. It was found that the mutation frequency of the Nebulin gene (NEB) at amino acid 1133 locus of thyroid cancer patients was much higher than that of the normal population, suggesting that NEB mutation may be related to thyroid cancer. Therefore, we constructed the NEB mutant mice for further investigation.Material/MethodsThe RNA extracted from the thyroid of wild-type and NEB mutant mice was analyzed by high-throughput sequencing, and the differential expression was analyzed by edgeR software. Several differentially expressed genes were selected for quantitative real-time PCR (qRT-PCR) verification, and these genes were analyzed with Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis.ResultsA total of 624 genes were significantly enriched. Analysis of GO function and pathway significant enrichment showed that differentially expressed genes were enriched in thyroid cancer, myocardial contraction, and autoimmune thyroid disease. The qRT-PCR results were consistent with the high-throughput sequencing results.ConclusionsOur data indicate that the expression of some cancer-driving genes and cancer suppressor genes are significantly changed in NEB mutant mice compared to wild-type mice, which suggests that NEB function plays an important role in regulating the expression of cancer-related genes in the thyroid gland.

Ex vivo model for elucidating the functional and structural differentiation of the embryonic mouse thyroid

Terminal thyroid gland differentiation - the last developmental step needed to enable thyroid hormone (T4) synthesis - involves profound structural and biochemical changes in the thyroid follicular cells (TFCs). We aimed to develop an ex vivo thyroid model of embryonic mouse thyroid that would replicate the in vivo TFC differentiation program. E13.5 thyroid explants were cultured ex vivo in chemically defined medium for 7 days. Immunostaining and qPCR of thyroid explants showed thyroglobulin production onset, follicle formation, and T4 synthesis onset in 1-, 3-, and 5-day-old cultures, respectively. Differentiation was maintained and follicular growth continued throughout the 7-day culture period. Pharmacological approaches to culture inhibition were performed successfully in the ex vivo thyroids. Our robust and well described ex vivo thyroid culture model replicates the sequence of thyroid differentiation to T4 synthesis seen in vivo. This model can be used to test the effects of pharmacological inhibitors on thyroid hormone production.

Protective Effects of Myo-Inositol and Selenium on Cadmium-Induced Thyroid Toxicity in Mice.

Cadmium (Cd) damages the thyroid gland. We evaluated the effects of myo-inositol (MI), seleno-L-methionine (Se) or their combination on the thyroids of mice simultaneously administered with Cd chloride (CdCl2). Eighty-four male mice were divided into 12 groups (seven mice each). Six groups (controls) were treated with 0.9% NaCl (vehicle), Se (0.2 mg/kg/day), Se (0.4 mg/kg/day), MI (360 mg/kg/day), MI+Se (0.2 mg/kg) and MI+Se (0.4 mg/kg). The other six groups were treated with CdCl2 (2 mg/kg), CdCl2+MI, CdCl2+Se (0.2 mg/kg), CdCl2+Se (0.4 mg/kg), CdCl2+MI+Se (0.2 mg/kg) and CdCl2+MI+Se (0.4 mg/kg). An additional group of CdCl2-challenged animals (n = 7) was treated with resveratrol (20 mg/kg), an effective and potent antioxidant. All treatments lasted 14 days. After sacrifice, the thyroids were evaluated histologically and immunohistochemically. CdCl2 reduced the follicular area, increased the epithelial height, stroma, and cells expressing monocyte chemoattractant protein-1 (MCP-1) and C-X-C motif chemokine 10 (CXCL10). CdCl2+Se at 0.2/0.4 mg/kg insignificantly reversed the follicular and stromal structure, and significantly decreased the number of MCP-1 and CXCL10-positive cells. CdCl2+MI significantly reversed the thyroid structure and further decreased the number of MCP-1 and CXCL10-positive cells. CdCl2+MI+Se, at both doses, brought all indices to those of CdCl2-untreated mice. MI, particularly in association with Se, defends mice from Cd-induced damage. The efficacy of this combination was greater than that of resveratrol, at least when using the follicular structure as a read-out for a comparison. We suggest that the use of these nutraceuticals, more specifically the combination of MI plus SE, can protect the thyroid of Cd-exposed subjects.