Thyrotropin Receptor, Thyrotropin and Mechanisms of Bone Loss

促甲状腺素受体、促甲状腺素与骨丢失机制

基本信息

批准号：
9906208
负责人：
TERRY Francis DAVIES
金额：
$ 59.07万
依托单位：
ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-04-01 至 2022-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9906208
关键词：
Affect Affinity Agonist American Anterior Pituitary Gland Anterior Pituitary Hormones Binding Bone Diseases Bone Marrow Cells Bone Resorption Bone remodeling Cells Clinical Clinical Research Closure by clamp Coculture Techniques Data Defect Dominant-Negative Mutation Dose Excision Flow Cytometry Genes Genetic Health Hormone replacement therapy Hormone secretion Hyperthyroidism Hypothyroidism Implant In Vitro Incidence Injections Mediating Mediation Mesenchymal Methimazole Modeling Molecular Mus Myocardial Infarction Osteoblasts Osteoclasts Osteogenesis Osteoporosis Osteoporotic Ovariectomy Patients Pharmacology Phenotype Pituitary Hormones Postmenopause Prevention Production Rattus Replacement Therapy Reproducibility Role Serum Signal Transduction Skeleton Specificity Stroke Stromal Cells TNF gene The Sun Thyroid Function Tests Thyroid Gland Thyroid Hormone Receptor Beta Thyroid Hormones Thyrotropin Thyrotropin Receptor Tumor Necrosis Factor Receptor United States Woman autoimmune thyroid disease bone bone cell bone loss bone mass cellular targeting cohort cytokine druggable target experimental study follow-up fracture risk malignant breast neoplasm men mouse model mutant nanomolar novel novel strategies osteoclastogenesis osteoporosis with pathological fracture overexpression prevent restoration skeletal small molecule

项目摘要

PROJECT SUMMARY In 2003, we showed that the anterior pituitary hormone thyrotropin (a.k.a. TSH), hitherto known to promote thyroid hormone secretion, is a potent direct regulator of bone mass (Abe et al, Cell, 2003, PMID: 14567913)1. This finding underscored a potential role for low circulating TSH levels in causing the bone loss that has been recognized in patients with hyperthyroidism for over a century2, and, by tradition, has been attributed solely to thyroid hormone excess. We found instead that Tsh receptor-deficient Tshr-/- mice had profound osteoporosis, even when rendered euthyroid1. Importantly, we showed more recently that bone loss in Tshr-/- mice rendered hyperthyroid significantly exceeded that in wild type hyperthyroid mice (Baliram et al, J Clin Invest, 2012, PMID: 22996689)3 – this finding not only confirmed a direct permissive action of Tshr deficiency on bone, but also buttressed multiple clinical studies showing a tight and highly reproducible correlation between low TSH levels, bone loss, and a high fracture risk in cohorts of hyperthyroid patients worldwide4-24. Furthermore, we found that the osteoclastogenic cytokine, Tnfα, was grossly elevated in Tshr-/- mice, and that its genetic deletion rescued the skeletal phenotype of Tshr deficiency (Hase et al, PNAS, 2006, PMID: 16908863; Sun et al, PNAS, 2013, PMID: 23716650)25,26. This led to the question: which cell – osteoblast or osteoclast – drives the effect, and which of the two Tnf receptors, Tnfrsf1a or Tnfrsf1b, mediate the action of Tnfα in Tshr deficiency? Specific Aim 1 will study mice in which the Tshr is deleted selectively in osteoblasts or osteoclasts, as well as double mutants in which both the Tshr and either Tnfrsf1a or Tnfrsf1b are deleted. Complementary co-culture experiments will determine if osteoblastic Tnfα mediates the hyper-resorption in Tshr-/- mice. A second corpus of data, confirmed by other groups27-33, showed that Tsh displays both anti- resorptive and anabolic actions1,34-37. For example, intermittent low dose Tsh injections restored the lost bone 7 months post-ovariectomy, importantly without elevating T4 levels (Sun et al, PNAS, 2008, PMID: 18332426)37. A follow-up question thus arises: is the Tshr a druggable target? Towards finding an answer, we will utilize both genetic and pharmacological approaches. In Specific Aim 2, we will examine whether high Tsh levels are anabolic using mice in which the expression of dominant-negative Trβ337 in the thyrotrope clamps Tsh at ~30-fold higher circulating levels. In Specific Aim 3, we will study the effects of a small molecule activator of the Tshr, MS438, which, we have found, binds Tshrs selectively and with a nanomolar affinity (Latif et al, Thyroid, 2015, PMID: 25333622)38. We also find that MS438 displays pro-osteoblastic and anti-osteoclastic actions in vitro, and does not elevate serum T4. We will thus inject mice with MS438 immediately (‘prevention’) or 7-months following (‘restoration’) ovariectomy to determine if it can prevent bone loss and/or restore the lost bone. Together, these studies should not only allow an in-depth understanding of Tsh action on bone, but also provide proof-of-concept for a new approach that targets the skeletal Tshr.

项目摘要在2003年，我们表明垂体前激素甲状腺蛋白（又称TSH），迄今已知可以促进的甲状腺激素分泌是骨骼质量的潜在直接调节剂（Abe等，Cell，2003，PMID：14567913）1。这一发现强调了低循环TSH水平在导致骨质流失的潜在作用在甲状腺功能亢进症的患者中被公认为一个世纪以上2，从传统上讲，它仅归因于甲状腺马内超过。相反，我们发现TSH受体缺陷型TSR - / - 小鼠患有严重的骨质疏松症，即使渲染甲状腺功能亢进1。重要的是，我们最近表明，TSHR - / - 小鼠的骨质流失甲状腺功能亢进明显超过了甲状腺甲状腺功能亢进小鼠（Baliram等，J Clin Invest，2012，2012， PMID：22996689）3 - 这一发现不仅证实了TSHR缺乏对骨骼的直接允许作用，而且还证实了还支持多个临床研究，表明低TSH之间的紧密相关性全球甲状腺功能亢进症患者队列中的水平，骨质流失和高骨折风险4-24。此外，我们发现在TSHR - / - 小鼠中严重升高了破骨细胞因子TNFα，并且其遗传删除恢复了TSHR缺乏症的骨骼表型（Hase等，PNAS，2006，PMID：16908863; Sun et et eT AL，PNA，2013年，PMID：23716650）25,26。这导致了一个问题：哪个细胞 - 成骨细胞或破骨细胞 - 驱动器两种TNF受体TNFRSF1A或TNFRSF1B的效果以及哪个效果介导TSHR中TNFα的作用不足？具体目标1将研究在成骨细胞中选择性删除TSHR的小鼠或删除了TSHR和TNFRSF1A或TNFRSF1B的破骨细胞以及双突变体。互补的共培养实验将确定成骨细胞TNFα是否介导 TSHR - / - 鼠标。其他组27-33确认的第二个数据库表明，TSH显示了两种抗吸收和合成代谢作用1,34-37。例如，间歇性低剂量TSH注射恢复了失去的骨头卵巢切除术后7个月，重要的是没有提高T4水平（Sun等，PNAS，2008，PMID： 18332426）37。因此出现了一个后续问题：TSHR是可吸毒的目标吗？寻找答案，我们将同时使用遗传和药物方法。在特定目标2中，我们将检查是否高 TSH水平是合成代谢的小鼠，其中甲状腺中显性阴性TRβ337的表达夹紧TSH的循环水平高约30倍。在特定目标3中，我们将研究一个小的效果 TSHR，MS438的分子激活剂，我们发现，它有选择地结合TSHR，并与纳摩尔结合亲和力（Latif等，甲状腺，2015年，PMID：2533622）38。我们还发现MS438显示pro-osteblastic和体外的抗骨碎屑作用，不会升高血清T4。因此，我们将向小鼠注入MS438 立即（“预防”）或7个月之后（“限制”）卵巢切除术，以确定是否可以预防骨骼损失和/或恢复失去的骨头。这些研究不仅应深入了解 TSH对骨骼的作用，但也为针对骨骼TSHR的新方法提供了概念验证。