Thyrotoxic osteoporosis, which is accompanied by a high fracture risk, is known to arise from pro-resorptive effects of high thyroid hormone. We reported that TSH-signaling deficient mice lacking the TSH receptor (TSHR) display severe osteoporosis, suggesting that low TSH levels also contribute to thyrotoxic bone loss. That haploinsufficient euthyroid TSHR mice had an equally profound phenotype suggested that the effects of TSH were independent of thyroid hormones. Nonetheless, it remains unclear whether TSHR activation by stimulating antibodies in Graves'disease reduces the hyperthyroid bone loss that is due to high thyroid hormones and low TSH. We further showed that TSHR activation inhibits osteoclast formation, function and survival, as well as the production of TNFa. When TNFa is ablated from TSHR-/- osteoclasts the enhanced osteoclastogenesis and osteopenia are both rescued, suggesting that TNFa plays a key role in thyrotoxic bone disease. Recently, we observed that TSH, when injected intermittently as far apart as once every two weeks, prevented and restored ovariectomy-induced bone loss by inhibiting bone resorption and stimulating bone formation. We hypothesize that TSH preserves the skeleton through potent anti-resorptive and anabolic actions, and that a loss of these actions contributes to the bone loss of hyperthyroidism. We will use genetically modified mice and state-of-the-art molecular approaches to understand the role of TSH in hyperthyroid bone loss. We will first attempt to rescue the TSHR-/- phenotype by deleting TNFa or its receptors, p55 or p75, in double mutants, or by transgenically reconstituting TSHRs in TSHR-/- osteoclasts or osteoblasts. Next, we will determine whether stimulating anti-TSHR antibodies given by injection or produced in vivo by adeno-TSHR immunization attenuate hyperthyroid bone loss. Finally, using mice in which TSHRs are restored cell-selectively in osteoclasts or osteoblasts on a TSHR-/- background, we will examine which cell contributes to the prevention and restoration of post-ovariectomy bone loss by TSH. These foundation studies should allow us to consider skeletal protection by TSH in post-menopausal women whose TSH levels are suppressed by thyroxine therapy for non-cancer causes.
Hyperthyroidism affects one in 1000 American women and is accompanied by osteoporosis and a high fracture risk. We showed that decrements in the pituitary hormone TSH accompany the high thyroid hormone levels, both of which contribute to the bone loss. This proposal examines the molecular mechanism through which TSH acts directly on the skeleton.
| Iqbal, Jameel; Yuen, Tony; Kim, Se-Min et al. (2018) Opening windows for bone remodeling through a SLIT. J Clin Invest 128:1255-1257 |
| Zaidi, Mone; Yuen, Tony; Sun, Li et al. (2018) Regulation of Skeletal Homeostasis. Endocr Rev 39:701-718 |
| Zaidi, Mone; New, Maria I; Blair, Harry C et al. (2018) Actions of pituitary hormones beyond traditional targets. J Endocrinol 237:R83-R98 |
| Ji, Yaoting; Liu, Peng; Yuen, Tony et al. (2018) Epitope-specific monoclonal antibodies to FSH? increase bone mass. Proc Natl Acad Sci U S A 115:2192-2197 |
| Khattab, Ahmed; Haider, Shozeb; Kumar, Ameet et al. (2017) Clinical, genetic, and structural basis of congenital adrenal hyperplasia due to 11?-hydroxylase deficiency. Proc Natl Acad Sci U S A 114:E1933-E1940 |
| Liu, Peng; Ji, Yaoting; Yuen, Tony et al. (2017) Blocking FSH induces thermogenic adipose tissue and reduces body fat. Nature 546:107-112 |
| Liu, Tong; Zhang, Hao; Sun, Li et al. (2017) FSIP1 binds HER2 directly to regulate breast cancer growth and invasiveness. Proc Natl Acad Sci U S A 114:7683-7688 |
| Kushwaha, Priyanka; Khedgikar, Vikram; Sharma, Deepika et al. (2016) MicroRNA 874-3p Exerts Skeletal Anabolic Effects Epigenetically during Weaning by Suppressing Hdac1 Expression. J Biol Chem 291:3959-66 |
| Sun, Li; Tamma, Roberto; Yuen, Tony et al. (2016) Functions of vasopressin and oxytocin in bone mass regulation. Proc Natl Acad Sci U S A 113:164-9 |
| Khattab, Ahmed; Yuen, Tony; Al-Malki, Sultan et al. (2016) A rare CYP21A2 mutation in a congenital adrenal hyperplasia kindred displaying genotype-phenotype nonconcordance. Ann N Y Acad Sci 1364:5-10 |
Showing the most recent 10 out of 43 publications
