Project description:Congenital hypothyroidism is a genetic condition in which the thyroid gland fails to produce sufficient thyroid hormone (TH), resulting in metabolic dysfunction and growth retardation. Xb130-/- mice exhibit perturbations of thyrocyte cytoskeleton and polarity, develop postnatal transient growth retardation due to congenital hypothyroidism and leading to multinodular goiter in elderly. To determine the underlying mechanisms, we performed transcriptomic analyses on thyroid glands of mice at three age points – week 2 (W2, before visible growth retardation), W4 (at the nadir of growth), and W12 (immediately before full growth recovery. We compared gene expression between Xb130+/+ and Xb130-/- mice.
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:We performed a whole-genome DNA methylation analysis (Infinium HumanMethylation450 BeadChip) on peripheral whole blood of 23 twin pairs (10 monozygotic and 13 dizygotic) heterogeneously (4 concordant and 19 discordant) affected by Congenital Hypothyroidism (CH) at birth.
Project description:Transcriptional profiling of rat liver comparing male rats with congenital hypothyrodism (CH) vs intact at adulhood. Here we studied how CH influences liver gene expression program in adulthood. Thyroid hormones are required for normal growth and development in mammals. Congenital-neonatal hypothyroidism (CH) has a profound impact on physiology but its specific influence in liver is less understood. Here we studied how CH influences liver gene expression program in adulthood. Pregnant rats were given anti-thyroid drug methimazole (MMI) from GD12 until PND30 to induce CH in male offspring. Growth defects due to CH were evident as a reduction in body weight and tail length from the second week of life. Once the MMI treatment was discontinued, feed efficiency increased in CH and this was accompanied by significant catch-up growth. On PND80, significant reduction in body mass, tail length, and circulating IGF-I remained in CH rats. On the other hand, mRNA levels of known GH targeted genes were significantly up-regulated. Serum levels of thyroid hormones, cholesterol, and triglycerides showed no significant differences. In contrast, CH rats showed significant changes in expression for hepatic genes involved in lipid metabolism with an increased transcription of PPAR and reduced expression of genes involved in fatty acids and cholesterol uptake, cellular sterol efflux, triglycerides assembly, bile acid synthesis, and lipogenesis. These changes were associated with a decrease of intrahepatic lipids. Finally, CH rats responded to hypothyroidism onset in adulthood with a reduction of serum fatty acids and hepatic cholesteryl esters, and to T3 replacement with enhanced activation of lipogenic transcriptional program. In summary, we provided in vivo evidence that neonatal hypothyroidism causes long-lasting effects on hepatic transcriptional program and tissue sensitivity to hormone treatment. This highlights the critical role that a euthyroid state during development plays on normal liver physiology in adulthood. Two conditions CH vs INTACT male rats. Biological replicates: Four independent hybridizations: 4 controls (age-matched intact rats) vs 4 CH (male rats with congenital hypothyroidism) on postnatal day 80 for a total of four arrays. One replicate per array.
Project description:Congenital Hypothyroidism occurs in 1:3500 live births and is therefore the most common congenital endocrine disorder. A spectrum of defective thyroid morphology, termed thyroid dysgenesis, represents 80% of permanent CH cases. Although several candidate genes have been implicated in thyroid development, comprehensive screens failed to detect mutation carriers in a significant number of patients with non-syndromic TD. Due to the sporadic occurrence of TD, de novo chromosomal rearrangements are conceivably representing one of the molecular mechanisms participating in its aetiology. Recently, the use of array CGH technique has provided the ability to map these variations genomewide with high resolution. We performed an array CGH screen of 74 TD patients to determine the role of copy number variants (CNV) in the aetiology of the disease. We identified novel CNVs in 8.75% of all patients that have not been described as frequent variations in the healthy population. Affected patients presented with athyreosis or thyroid hypoplasia and in one case with associated heart malformation.
Project description:Whole-exome sequencing of a cohort of families (probands and affected/unaffected relatives) suffering from one of two rare thyroid disorders: congenital hypothyroidism (CH) and resistance to thyroid hormone (RTH).