D2 TANTYCYTES IN THE REGULATION OF HPT AXIS

描述（取自应用程序） 这项研究的长期目标是阐明控制的机制， 在基础条件下和在 当这种调节系统受到环境压力因素的干扰时， 或以低循环甲状腺激素为特征的疾病状态 TSH异常低（非甲状腺疾病综合征）。我们最近 证明存在大浓度的2型碘甲腺原氨酸 脱碘酶（D2）mRNA在一组专门的胶质细胞内衬地板， 第三脑室的下外侧壁，称为D2伸长细胞。自D2起 将甲状腺素（T4）转化为更具生物活性的甲状腺激素， 三碘甲腺原氨酸（T3），我们提出，D2伸长细胞包括一部分， 以前未认识到的HPT轴的调节成分。我们进一步 提出，通过与脑脊液和神经元的相互作用， 邻近下丘脑弓状核，D2伸长细胞调节 甲状腺激素对甲状腺细胞TRH基因表达的反馈调节 下丘脑室旁核R21试点项目的目的和 可行性建议是开发动物模型来测试的重要性， D2伸展细胞对HPT轴的调节，并开始阐明 这种调节的机制。两种不同的方法来 在伸长细胞中建立D2缺乏或D2过表达的动物模型 将用于在第一个模型中，表达反义或反义核酸的腺病毒， 过表达正义D2 mRNA将用于在立体定位后感染伸长细胞。 将病毒注射到第三脑室或正中隆起。第二 该模型将涉及使用DARPP-32基因的转基因小鼠的开发 作为将反义或正义D2转录物靶向伸长细胞的工具。 D2反义和正义转录物在伸长细胞中表达的功效 将通过测量中基底膜提取物中的D2活性来确定 下丘脑，和特异性的伸长细胞证明了原位 杂交组织化学D2缺失和过表达在人乳腺癌中的作用 HPT轴上的伸长细胞将在基础条件下或在 甲状腺功能减退和禁食动物。由于DARPP-32的共存， 磷酸酶抑制剂和D2，我们还将确定是否 DARPP-32通过测量循环甲状腺功能对D2发挥调节作用。 甲状腺功能减退时伸长细胞中的激素水平和D2活性， DARPP-32基因敲除小鼠禁食。

DESCRIPTION (taken from the application) The long term goals of this study are to elucidate the mechanisms of control of the hypothalamic-pituitary-thyroid (HPT) axis under basal conditions and during conditions when this regulatory system is perturbed by environmental stressors or disease states characterized by low circulating thyroid hormone and inappropriately low TSH (nonthyroidal illness syndrome). We have recently demonstrated the presence of large concentrations of type 2 iodothyronine deiodinase (D2) mRNA in a group of specialized glial cells lining the floor and infralateral wall of the third ventricle, termed D2 tanycytes. Since D2 converts thyroxine (T4) to the more biologically active thyroid hormone, triiodothyronine (T3), we propose that D2 tanycytes comprise part of a previously unrecognized regulatory component of the HPT axis. We further propose that via interactions with the cerebrospinal fluid and neurons in the adjacent hypothalamic arcuate nucleus, D2 tanycytes modulate the set point for feedback regulation of thyroid hormone on the gene expression of TRH in the hypothalamic paraventricular nucleus. The purpose of this R21 Pilot and Feasibility Proposal is to develop animal models to test the importance of the D2 tanycyte on the regulation of the HPT axis and begin to elucidate the mechanisms by which this regulation occurs. Two different approaches to developing animal models with D2 deficiency or D2 overexpression in tanycytes will be used. In the first model, adenovirus that express antisense or overexpress sense D2 mRNA will be used to infect tanycytes after stereotaxic injection of the virus into the third ventricle or median eminence. The second model will involve the development of transgenic mice, using the DARPP-32 gene as a tool to target antisense or sense D2 transcripts to the tanycytes. Efficacy of expression of the D2 antisense and sense transcripts in tanycytes will be determined by measuring D2 activity in extracts from the mediobasal hypothalamus, and the specificity for tanycytes demonstrated by in situ hybridization histochemistry. The effect of D2 depletion and overexpression in tanycytes on the HPT axis will then be studied under basal conditions or in hypothyroid and fasting animals. Due to the coexistence of DARPP-32, a phosphatase inhibitor, and D2 in tanycytes, we will also determine whether DARPP-32 exerts a regulatory function on D2 by measuring circulating thyroid hormone levels and D2 activity in tanycytes in response to hypothyroidism and fasting in the DARPP-32 knock-out mouse.