PHYSIOLOGY OF THYROID HORMONE-DEPENDENT GENE EXPRESSION

这项提案将调查甲状腺状况的局部和系统控制的几个方面 碘甲腺原氨酸脱碘酶、D2和D3。这些酶激活甲状腺激素(T4)、(D2)或使T4失活 3，5，3‘三碘甲腺原氨酸或T3(D3，D1)。我们的研究表明，D2在人类骨骼中起着关键作用 肌肉。因此，在特定的目标1中，我们将分析人骨骼原代培养中的内源性D2 肌肉及其对肌肉新陈代谢的影响。我们的假设是D2的增加会增加 因此，细胞内T3浓度只增加了肌肉的能量消耗，而不会导致全身 甲状腺毒症。在确认T4(通过D2)将引起与相同的肌肉代谢变化之后 T3，我们将在一只新的转基因小鼠中建立这个系统的模型，通过在骨骼肌中特异地表达D2 在多西环素(Tet-on)的控制下。这只小鼠在甲状腺经济方面的特点是 在美国和关于代谢参数方面，我们与Jason Kim博士合作。考虑到 这种由脱碘酶介导的T_3稳态的适应性控制和最近的研究发现刺猬 (HH)蛋白质调节D2，在特定目标2中，我们将测试这是更多 包括D3在内的综合机制。我们将使用皮肤，这是HH系统的一个很好的目标， 作为测试这一概念的模型。我们将分析D3在皮肤发育过程中的表达，毛囊 形态发生、伤口愈合和肿瘤发生。我们将确定刺猬蛋白的影响 以及其他本地生产的因素通过它们对D3和D2的影响来影响这些过程。这些研究是 旨在增进我们对有关甲状腺激素经济和 行动。我们的发现将对理解和潜在地开发新的 治疗人类肥胖，这是美国的一个主要健康问题，用于伤口愈合和初级皮肤 恶性肿瘤。他们将从人类最大的器官皮肤中定义调节甲状腺状态的因素 从其作为刺猬之间协同互动的模式在发展中的作用的角度 蛋白质、生长因子和甲状腺激素。

This proposal will investigate several aspects of the local and systemic control of thyroid status by the iodothyronine deiodinases, D2 and D3. These enzymes activate thyroxine (T4), (D2), or inactivate T4 and 3, 5, 3' triiodothyronine or T3 (D3, D1). Our studies indicate that D2 plays a critical role in human skeletal muscle. Thus, in Specific Aim 1, we will analyze endogenous D2 in primary cultures of human skeletal muscle and the effect of this on muscle metabolism. Our hypothesis is that an increase in D2 will increase intracellular T3 concentration thus increasing energy expenditure in muscle only, without causing systemic thyrotoxicosis. After confirming that T4 (via D2) will cause the same changes in muscle metabolism as does T3, we will model this system in a new transgenic mouse by expressing D2 exclusively in skeletal muscle under control of doxycycline (TET-ON). This mouse will be characterized with respect to thyroid economy by us and with respect to metabolic parameters in collaboration with Dr. Jason Kim. Given the relevance of this adaptive control of T3 homeostasis mediated by the deiodinases and the recent finding that hedgehog (Hh) proteins regulate D2, in Specific Aim 2 we will test the hypothesis that this is part of a more comprehensive mechanism that includes D3. We will use skin, a well-characterized target of the Hh system, as a model to test this concept. We will analyze the expression of D3 in skin during development, hair follicle morphogenesis, wound healing, and tumorigenesis. We will determine the influence of hedgehog proteins and other locally produced factors on these processes via their effects on D3 and D2. These studies are designed to advance our knowledge of fundamental questions regarding thyroid hormone economy and action. Our findings will be highly relevant for the understanding of and potentially developing new treatments for human obesity, a major health issue in the US, for wound healing, and for primary skin malignancies. They will define factors regulating thyroid status in skin, the largest organ in humans, from the point-of-view of its role in development as a model for the synergistic interactions between hedgehog proteins, growth factors, and thyroid hormones.