Project description:Test for thyroid hormone regulation of genes expressed in the abdominal aorta of C57Bl6 mice. Comparison between mice treated with 1mg/L Thyroxin in drinking water for 4 days compared to controls.
Project description:Background: Sex and age have substantial influence on thyroid function. Sex influences the risk and clinical expression of thyroid disorders (TDs), with age a proposed trigger for the development of TDs. Cardiac function is affected by thyroid hormone levels with gender differences. Accordingly, we investigated the proteomic changes involved in sex based cardiac responses to thyroid dysfunction in elderly mice. Methods: Aged (18-20 months) male and female C57BL/6 mice were fed diets to create euthyroid, hypothyroid, or hyperthyroid states. Serial echocardiographs were performed to assess heart function. Proteomic changes in cardiac protein profiles were assessed by 2-D DIGE and LC-MS/MS, and a subset confirmed by immunoblotting. Results: Serial echocardiographs showed ventricular function remained unchanged regardless of treatment. Heart rate and size increased (hyperthyroid) or decreased (hypothyroid) independent of sex. Pairwise comparison between the six groups identified 55 proteins (≥ 1.5-fold difference and p < 0.1). Compared to same-sex controls 26/55 protein changes were in the female hypothyroid heart, whereas 15/55 protein changes were identified in the male hypothyroid, and male and female hyperthyroid heart. The proteins mapped to oxidative phosphorylation, tissue remodeling and inflammatory response pathways. Conclusion: We identified both predicted and novel proteins with gender specific differential expression in response to thyroid hormone status, providing a catalogue of proteins associated with thyroid dysfunction. Pursuit of these proteins and their involvement in cardiac function will expand our understanding of mechanisms involved in sex-based cardiac response to thyroid dysfunction.
Project description:Perfluorooctanesulfonic acid (PFOS) is a persistent anthropogenic chemical that can affect the thyroid hormone system in humans. In experimental animals, PFOS exposure decreases thyroxine (T4) and triiodothyronine (T3) levels, without a compensatory upregulation of thyroid stimulating hormone (TSH). In adults, THs are regulated by the hypothalamus-pituitary-thyroid (HPT) axis, but also organs such as the liver and potentially the gut microbiota. PFOS and other xenobiotics can therefore potentially disrupt the TH system through various entry points of disruption. To start addressing this issue, we performed a PFOS exposure study to identify effects in multiple organs and pathways simultaneously.
Project description:Animals adapt to environmental conditions by modifying the function of their internal organs, including the brain. To be adaptive, alterations in behavior must be coordinated with the functional state of organs throughout the body. Here we find that thyroid hormone--a regulator of metabolism in many peripheral organs--directly activates cell-type specific transcriptional programs in frontal cortex of adult male mice. These programs are enriched for axon-guidance genes in glutamatergic projection neurons, synaptic regulatory genes in both astrocytes and neurons, and pro-myelination factors in oligodendrocytes, suggesting widespread plasticity of cortical circuits. Indeed, whole-cell electrophysiology revealed that thyroid hormone alters excitatory and inhibitory synaptic transmission, an effect that requires thyroid hormone-induced gene regulatory programs in presynaptic neurons. Furthermore, thyroid hormone action in frontal cortex regulates innate exploratory behaviors and causally promotes exploratory decision-making. Thus, thyroid hormone acts directly on cerebral cortex in males to coordinate exploratory behaviors with whole-body metabolic state.
Project description:We investigated the effects of thyroid hormone disruptions on gene expression in juvenile mice liver to develop a stronger understanding of the mechanisms by which thyroid disrupting chemicals impair development. Gene expression was examined by hybridization of hepatic RNA to Agilent mouse microarrays for hyper-, hypo-, hypo-replacement (hypo+) and euthyroid animals. Keywords: Toxicogenomics, biomarkers of thyroid disruptors
Project description:Using tadpoles mutant for thyroid hormone receptor alpha (thra), we show that TRa is required for thyroid hormone (T3) induction of cell proliferation in the brain. RNA-sequencing showed that the TRa is required for 95% of the gene regulation responses to T3.
Project description:Thyroid hormones are important for homeostatic control of energy metabolism and body temperature. Although skeletal muscle is considered an important site for thyroid action, the contribution of thyroid hormone receptor signaling, in muscle, to whole-body energy metabolism and body temperature has not been resolved. Here, we show that thyroid hormone-induced increase in energy expenditure requires thyroid hormone receptor alpha 1 (TRa1) in skeletal muscle, but that thyroid hormone induced elevation in body temperature is independent of muscle-TRa1. In slow-twitch soleus muscle, ablation of TRa1 leads to an altered fiber type composition toward a more oxidative phenotype, which, however, does not influence running capacity or motivation to voluntary running. RNA-sequencing of soleus muscle from WT mice and TRaHSACre mice revealed differentiated transcriptional regulation of genes associated with muscle thermogenesis, such as sarcolipin and UCP3, thus providing molecular clues pertaining to the mechanistic underpinnings of TRa1-linked control of whole-body metabolic rate. Together, this work establishes a fundamental role for skeletal muscle in thyroid hormone-stimulated increase in whole-body energy expenditure.