Project description:Deficiency in Krüppel-like zinc finger transcription factor, GLI-Similar 3 (GLIS3) in humans is associated with the development of congenital hypothyroidism. However, the functions of GLIS3 in the thyroid gland and by what mechanism GLIS3-dysfunction causes hypothyroidism are unknown. In this study, we demonstrate that GLIS3 acts downstream of thyroid stimulating hormone (TSH)/TSHR and is indispensable for TSH/TSHR-mediated induction of thyroid follicular cell proliferation and thyroid hormone biosynthesis. ChIP-Seq and promoter analysis revealed that GLIS3 is critical for the transcriptional activation of several genes required for thyroid hormone biosynthesis, including the iodide transporters Nis and Pds, indicating that these genes are directly regulated by GLIS3. The repression of cell proliferation regulatory genes is due to the inhibition of TSH-mediated activation of the mTORC1/RPS6 pathway as well as direct transcriptional regulation of several cell division-related genes by GLIS3. Consequently, GLIS3-deficiency prevents the development of goiter as well as the induction of inflammatory and fibrotic genes during chronic elevation of circulating TSH. Our study identifies GLIS3 as a new and key regulator of TSH/TSHR-mediated thyroid hormone biosynthesis and proliferation of thyroid follicular cells, and uncovers a mechanism by which GLIS3-deficiency causes congenital hypothyroidism and prevents goiter development.
Project description:The serum hormone levels including T3 and T4 were dramatically decreased in Glis3-null mice due to reduced production of thyroid hormones in thyroid. Gene expression profile and EdU incorporation analysis between WT and Glis3-null mice showed that the cell proliferation was greatly reduced in Glis3-null thyroid. Goitergenic diet (low iodine diet; LID) dramatically enhanced serum TSH levels in both WT and Glis3-null mice, however thyroid goiter was observed in WT mice but not in Glis3-null mice. A subset of genes associated with thyroid hormone production including Pendrin (Slc26a4), Nis (Na+/I– symporter, Slc5a5), Duoxa2 (dualoxidase A2), Tpo (thyroperoxidase), and Dio1 (Deiodinase1) was significantly induced in WT but not in Glis3-null mice by LID feeding.
Project description:Comparison of cistromes from PAX8, NKX2.1, and FOXE1 ChIP-Seq analysis using mouse thyroid gland and rat thyrocyte PCCl3 cells revealed that there is a significant overlap between GLIS3 binding regions and those of PAX8, NKX2.1, and FOXE1 in genes associated with thyroid hormone biosynthesis.
Project description:Transcriptomic signature of human embryonic thyroid is not described so far. The goal of this project was to evaluate what enables the transition from differentiation to functional maturation of the human developing thyroid, by performing transcriptomic analysis of human thyroids covering the period of gestation weeks 7-11 and comparing it to adult human thyroids. We defined a non TSH (thyroid stimulating hormone) dependent transition from differentiation to maturation of thyroid. The study also sought to shed light on possible factors that could replace TSH, which is absent in this window of gestational age, to trigger transition to the emergence of thyroid function.
Project description:Subclinical hyperthyroidism, a disease characterized by decreased thyroid-stimulating hormone (TSH) and normal concentration of thyroid hormone, is associated with an elevated risk for cognitive impairment. TSH is the major endogenous ligand of TSH receptor (TSHR) and its role dependent on the process of signal transduction of TSHR. It has not, however, been established whether TSHR signaling are involved in the regulation of cognition. In the current study, Tshr deletion leads to significantly compromised performance in hippocampus-dependent tasks, along with reduced dendritic spine density and excitatory synaptic density as well as altered synaptic structure in CA1 subfield of the hippocampus. Furthermore, the synapse-related gene expression was altered in the hippocampus of Tshr-/- mice. These findings suggest the ablation of TSHR signaling impairs spatial learning and memory, which reveals a fresh role of TSHR signaling in brain.
Project description:Thyroid hormone receptor beta (THRB) is post-translationally modified by small ubiquitin-like modifier (SUMO). To investigate the biological role of THRB sumoylation, we generated a mouse model with a mutation that disrupts sumoylation at lysine 146 (K146Q). The THRB K146Q mutant mice had normal serum thyroxine (T4), markedly elevated serum thyrotropin (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 concentration, indicated blunted feedback regulation of TSH. TH profuction was 10-fold lower (per mg of thyroid tissue) in mutant mice compared to Wt mice.
Project description:We developed a novel culture system to obtain multilineage undifferentiated stem/progenitor cells from normal human thyroid tissues. This seems to be achieved by direct reprogramming of thyroid follicular cells. The objective of the study was to reveal gene expression profile of the obtained cells compared to primary thyrocytes. After enzymatic digestion, primary thyrocytes, expressing thyroglobulin and cytokeratin-18, were cultured in a serum-free medium called SAGM containing insulin and EGF. Although the vast majority of cells died, a small proportion (~0.5%) survived and proliferated. During initial cell expansion, thyroglobulin/cytokeratin-18 expression was gradually declined, suggesting that those cells are derived from thyroid follicular cells or at least thyroid-committed cells. The SAGM-grown cells did not express any thyroid-specific genes. However, after four-week incubation with FBS and TSH, cytokeratin-18, thyroglobulin, TSH receptor, PAX8 and TTF1 expressions re-emerged. Moreover, surprisingly, the cells were capable of differentiating into neuronal or adipogenic lineage depending on differentiating conditions. Total RNAs were extracted from PT from three different samples (PT0808, PT0811 and PT0812) and corresponding SAGM-grown lines and subjected to Affymetrix GeneChip Human Genome U133 Plus 2.0 microarray analysis
Project description:Graves’ disease is characterized by goiter, palpitation and exophthalmos (Merseburg’s trias). However, a few patients develop exophthalmos even though their thyroid function is normal, a condition known as euthyroid Graves’ disease (EGD). It remains unknown why these patients remain euthyroid, even though they have potent thyroid-stimulating antibody (TSAb). To investigate whether the immunoglobulins (IgGs) obtained from EGD patients elicit thyroid hormone-releasing activity (THRA), thyroid follicles obtained from Graves’ patients were cultured in agarose-coated culture dishes, and 125I incorporated into the thyroid follicles and organic 125I (mainly de novo-synthesized 125I-T3+125I-T4) released into the culture medium by TSH or purified IgGs were determined as thyroid hormone-releasing activity (THRA). This thyroid follicle culture system allows maintenance of the Wolff-Chaikoff effect, and the expression of mRNA for the sodium-iodide symporter is decreased by high concentrations of iodide (10-6-10-4M) and therapeutic concentrations of amiodarone (1-2microM). hTSH elicited THRA most efficiently at 0.4-10 microU/ml, suggesting that thyroid function is controlled within the normal range of TSH concentration (0.4-4.0 microU/ml). All IgGs obtained from hyperthyroid Graves’ patients elicited THRA equivalent to more than 4.6 microU/ml hTSH. IgGs obtained from EGD patients also had potent THRA, whereas IgGs obtained from normal subjects and Graves’ patients in complete remission had no significant THRA. When thyroid follicles from Graves’ thyroid, into which a number of lymphocytes had infiltrated, were used, only slight THRA was elicited by bTSH or Graves’ IgGs, probably due to inflammatory cytokines produced by immunocompetent cells that could not be separated during gentle centrifugation. Indeed, when thyroid follicles were cultured with autologous intrathyroidal lymphocytes, interleukin-2 completely abolished TSH-induced THRA. When thyroid follicles were cultured with inflammatory cytokines (interleukin-1, tumor-necrosis factor-alpha, or interferon-gamma), each cytokine inhibited TSH-induced THRA in a concentration-dependent manner. These cytokines at lower concentrations synergistically and completely inhibited TSH-induced THRA. Microarray analyses of thyroid follicles cultured with IL-1alpha, TNF-alpha, or INF-gamma revealed decreased expression of mRNAs for TSHR, NIS, TPO and thyroglobulin, accompanied by increased expression of mRNAs for chemokines and cytokines. These findings suggest that IgGs obtained from patients with EGD have potent THRA in vitro, whereas in vivo, these IgGs are unable to elicit biological activity in the thyroid gland. Presumably, immunocompetent cells that infiltrate the thyroid gland produce inflammatory cytokines that synergistically inhibit thyroid function. Since a similar phenomenon may occur in the retroorbital tissues, these patients may develop exophthalmos despite having a normal serum level of TSH. This data will be published in Hyperthyroidism: Etiology, Diagnosis and Treatment (editor-in-chief;Dr.Frank Clumbus,Nova Science Publishers, Inc, New York, USA) Experiment Overall Design: One conditioned experiments: control vs. IL-1 alpha 5ng/ml, cultured for 24 hours; control vs. TNF alpha 20ng/ml, cultured for 24 hours; control vs. IFN gamma 1000U/ml, cultured for 48 hours.
Project description:We developed a novel culture system to obtain multilineage undifferentiated stem/progenitor cells from normal human thyroid tissues. This seems to be achieved by direct reprogramming of thyroid follicular cells. The objective of the study was to reveal gene expression profile of the obtained cells compared to primary thyrocytes. After enzymatic digestion, primary thyrocytes, expressing thyroglobulin and cytokeratin-18, were cultured in a serum-free medium called SAGM containing insulin and EGF. Although the vast majority of cells died, a small proportion (~0.5%) survived and proliferated. During initial cell expansion, thyroglobulin/cytokeratin-18 expression was gradually declined, suggesting that those cells are derived from thyroid follicular cells or at least thyroid-committed cells. The SAGM-grown cells did not express any thyroid-specific genes. However, after four-week incubation with FBS and TSH, cytokeratin-18, thyroglobulin, TSH receptor, PAX8 and TTF1 expressions re-emerged. Moreover, surprisingly, the cells were capable of differentiating into neuronal or adipogenic lineage depending on differentiating conditions.