MECHANISMS OF THYROID HORMONE ACTION IN DEVELOPMENT

描述（改编自申请人的摘要）： 本研究项目旨在阐明 甲状腺激素（TH）作用。 具体而言，该提案涉及 发育中脊椎动物TH代谢调控的分子机制 物种 胎儿和成人一样， 将甲状腺素和其他甲状腺激素转化为活性和非活性 代谢物。 最近，一种编码I型大鼠肝脏5 '- 分离出脱碘酶（5 ′ D）并测定其序列。 因此，研究 在分子水平上，旨在研究 脱碘酶在发育过程中的调节现在可以进行。两 将采用动物模型：大鼠，其传统上被用作 用于研究哺乳动物TH经济的实验模型系统，以及青蛙， 其主要优点是其幼虫形式是自由游泳， 因此易于进行实验操作。 具体目标1是 分离并表征蝌蚪中存在的5 ′ D和5D的cDNA。 在 具体目标2和#4这些蝌蚪和大鼠cDNA将被用作分子标记物。 表征脱碘酶翻译前调节的探针 酶在不同的发展阶段，通过定量mRNA水平， 原位杂交 TH等因子在调节5 ′ D中的作用 将在大鼠胎儿和蝌蚪中研究5D mRNA水平 （特定目标3）和培养的胎鼠肝细胞和蝌蚪尾 提示（具体目标5）。 TH对5'D和5D基因转录的影响 然后将使用转录测定（特异性目的6）来确定。 具体目标#7是从青蛙和大鼠基因组文库中分离基因 其编码5'D和5D及其相关的DNA侧翼区。

DESCRIPTION (Adapted from the applicant's abstract): The long term goal of this research project is to elucidate the cellular processes involved in thyroid hormone (TH) action. Specifically, this proposal addresses the molecular mechanisms which regulate TH metabolism in developing vertebrate species. In the fetus, as in the adult, specific iodothyronine deiodinases convert thyroxine and other thyroid hormones into active and inactive metabolites. Recently, a cDNA which encodes the type I rat liver 5'- deiodinase (5'D) was isolated and its sequence determined. Thus, studies at a molecular level aimed at investigating the mechanisms by which deiodinases are regulated during development can now be undertaken. Two animal models will be employed: the rat, which is traditionally used as an experimental model system for studying mammalian TH economy, and the frog, which offers the major advantage that its larval form is free swimming and thus readily amenable to experimental manipulation. Specific Aim 1 is to isolate and characterize cDNAs for the 5'D and 5D present in tadpoles. In Specific Aim 2 and #4 these tadpole and rat cDNAs will be used as molecular probes to characterize the pretranslational regulation of the deiodinase enzymes at various stages of development by quantitating mRNA levels and by in situ hybridization. The role of TH and other factors in regulating 5'D and 5D mRNA levels will be investigated in rat fetuses and tadpoles (Specific Aim 3) and in cultured fetal rat hepatocytes and tadpole tail tips (Specific Aim 5). The effect of TH on 5'D and 5D gene transcription will then be determined using a transcription assay (Specific Aim 6). Specific Aim #7 is to isolate from frog and rat genomic libraries the genes which encode the 5'D and 5D and their associated DNA flanking regions.