Our laboratory is currently characterizing in vitro and ex vivo the functional activity of common polymorphisms of type-2 deiodinase gene. In order to achieve this goal, we have established a cell culture-based type-2 deiodinase expression system. Standard biochemistry methods are utilized for the enzymatic activity assay;protein/protein and nucleic acids/protein interactions are tested by immunoprecipitation and mobility shift assay. A common polymorphism in the 5UTR region of the DIO2 gene (258 A/G DIO2) has been associated with a shift in the ratio of circulating T3/T4, suggesting an increased in the activity of the enzyme in vivo leading to a shift of the reaction equilibrium. Our in vitro and ex vivo data, consistent with others genotype/phenotype association studies, indicate that the 258 A/G DIO2 variant induces an increase in the transcription of the gene by displacing a putative repressor. Current efforts are aimed to characterize the putative repressor factor interacting with the polymorphism. Pathophysiology of thyrotoxicosis in patients affected by McCune-Albright syndrome. The clinical observation that McCune-Albright syndrome (MAS) is associated with hyperthyroidism with a shift in the ratio of circulating T3/T4 has led to the hypothesis that this finding could be at least in part explained by a an intra-thyroidal activation of the type-2 deiodinase gene. This is in keeping with the molecular pathology of MAS, i.e. activating mutations in GNAS1 gene resulting in ligand-independent inappropriately elevated levels of intracellular cAMP. We thus speculated that activation of the cAMP-driven deiodinase type-2 gene could explain at least in part these findings. Our in vitro and ex-vivo data indicate that, consistent with our experimental hypothesis, the type-2 deiodinase is constitutively activated in MAS. The results of these experiments have been published in the Journal of Clinical Endocrinology and Metabolism. Current collaborative efforts with Dr. Collins (NIDCR) are aimed to develop an in vitro system to test specific inhibitors of the mutant alleles of GNAS. Pre-adipocyte differentiation and culture. During FY09 we have focused our effort in developing a system of re-differentiation of human adipocytes from stromal cells obtained during adipose tissue biopsy. This system allows to test in a controlled fashion the effects of specific genotypes on adipose tissue function independently of the metabolic status of the subject at the time of the sampling. We are currently using this experimental model to characterize the role of thyroid hormones in the differentiation of the adipocytes. Further effort is directed toward characterizing the transcriptional pattern of this system throughout the differentiation process with a particular focus on the expression of brown-fat specific genes. Type-2 deiodinase assay in primary culture of follicular thyroid cells. Collaborative work carried out with Dr. Gershengorns group (NIDDK-CEB) has led to the development of a reliable assay for the measurement of type-2 deiodinase activity in primary cultures of thyroid cells as a read-out of TSH-cAMP pathway. This system has been successfully utilized to test the activity of agonists of the TSH receptor. The results of this effort have been recently published in a high-impact journal.

Project Start
Project End
Budget Start
Budget End
Support Year
6
Fiscal Year
2009
Total Cost
$516,938
Indirect Cost
City
State
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Zip Code
Vicinanza, Roberto; Coppotelli, Giuseppe; Malacrino, Carolina et al. (2013) Oxidized low-density lipoproteins impair endothelial function by inhibiting non-genomic action of thyroid hormone-mediated nitric oxide production in human endothelial cells. Thyroid 23:231-8
Sadowski, Samira M; He, Mei; Gesuwan, Krisana et al. (2013) Prospective screening in familial nonmedullary thyroid cancer. Surgery 154:1194-8
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Lee, Paul; Brychta, Robert J; Linderman, Joyce et al. (2013) Mild cold exposure modulates fibroblast growth factor 21 (FGF21) diurnal rhythm in humans: relationship between FGF21 levels, lipolysis, and cold-induced thermogenesis. J Clin Endocrinol Metab 98:E98-102
Wang, Ping-Yuan; Ma, Wenzhe; Park, Joon-Young et al. (2013) Increased oxidative metabolism in the Li-Fraumeni syndrome. N Engl J Med 368:1027-32
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Peltsverger, Maya Y; Butler, Peter W; Alberobello, Anna Teresa et al. (2012) The -258A/G (SNP rs12885300) polymorphism of the human type 2 deiodinase gene is associated with a shift in the pattern of secretion of thyroid hormones following a TRH-induced acute rise in TSH. Eur J Endocrinol 166:839-45
Regard, Jean B; Cherman, Natasha; Palmer, Daniel et al. (2011) Wnt/?-catenin signaling is differentially regulated by G? proteins and contributes to fibrous dysplasia. Proc Natl Acad Sci U S A 108:20101-6
Alberobello, Anna Teresa; Congedo, Valentina; Liu, Hong et al. (2011) An intronic SNP in the thyroid hormone receptor ýý gene is associated with pituitary cell-specific over-expression of a mutant thyroid hormone receptor ýý2 (R338W) in the index case of pituitary-selective resistance to thyroid hormone. J Transl Med 9:144

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