Tanycytes and Nonthyroidal Illness

描述（由申请人提供）：伸长细胞是一种特化的室管膜细胞，高密度分布于下丘脑正中隆起吻端和尾端之间的第三脑室底和腹侧壁。对这些细胞知之甚少，但它们表达的2型碘甲状腺原氨酸去碘酶（D2）（一种对甲状腺激素转化为活性形式至关重要的酶）以及对一些动物物种的禁食和内毒素的反应性，提出了细长细胞参与能量稳态的可能性，并有助于在严重感染的个体中循环甲状腺激素水平下降的机制，称为“非甲状腺疾病综合征”。为了通过对弓形核中下丘脑-垂体-甲状腺（HPT）轴和摄食相关中心的影响来了解细胞在神经内分泌调节中的重要性，我们建议使用激光捕获显微解剖和微阵列分析来鉴定细胞特异性基因，并开发在细胞中特异性表达Cre重组酶的转基因小鼠。这些小鼠将用于开发单细胞培养系统，并通过与crei诱导的白喉毒素受体小鼠系杂交后，开发双转基因小鼠特异性地在体内切除α和/或β。这些研究有望对伸长细胞的生物学重要性及其在HPT轴的神经内分泌调节和能量稳态中的作用提供新的信息。公共卫生相关性：伸长细胞是排列在第三脑室底和腹侧壁上的特化细胞。令人信服的证据表明，由于2型碘甲状腺原氨酸脱碘酶的高表达，它们在甲状腺激素的产生中起着重要作用，这种酶对于将激素原T4转化为具有生物活性的甲状腺激素T3至关重要。因此，我们提出，伸长细胞参与调节下丘脑-垂体-甲状腺（HPT）轴和能量稳态。为了便于研究这些细胞在神经内分泌调节中的作用，我们将通过激光捕获显微解剖和微阵列分析来鉴定鞣皮细胞特异性基因，以培养在鞣皮细胞中特异性表达Cre重组酶的转基因小鼠。这些小鼠将用于培养双转基因小鼠，其中伸长细胞被选择性地切除或用GFP标记，以便通过荧光激活细胞分选（FACS）进行组织培养分离。

DESCRIPTION (provided by applicant): Tanycytes are specialized ependymal cells found in high density along the floor and ventrolateral walls of the third ventricle between the rostral and caudal limits of the hypothalamic median eminence. Little is known about these cells but their expression of type 2 iodothyronine deiodinase (D2), an enzyme critical for conversion of thyroid hormone into its active form, and responsiveness to fasting and endotoxin in several animal species, has raised the possibility that tanycytes are involved in energy homeostasis and contribute to the mechanism by which circulating thyroid hormone levels fall in individuals with severe infection, termed the "nonthyroidal illness syndrome". To facilitate understanding of the importance of tanycytes in neuroendocrine regulation through effects on the hypothalamic-pituitary-thyroid (HPT) axis and feeding-related centers in the arcuate nucleus, we propose to identify tanycytes-specific genes using laser capture microdissection and microarray analysis and develop transgenic mice that express Cre recombinase specifically in tanycytes. These mice will be used to develop a tanycyte cell culture system, and to specifically ablate alpha and/or beta n vivo by developing double transgenic mice after crossing with a Cre-inducible diphtheria toxin receptor mouse line. These studies are expected to generate new information about the biologic importance of tanycytes and their role in neuroendocrine regulation of the HPT axis and in energy homeostasis. PUBLIC HEALTH RELEVANCE: Tanycytes are specialized cells that line the floor and ventrolateral walls of the third ventricle. Compelling evidence suggests they have an important role in generating thyroid hormone due to high expression of type 2 iodothyronine deiodinase, an enzyme critical for conversion of the prohormone, T4, into the biologically active thyroid hormone, T3. We have proposed, therefore, that tanycytes are involved in regulation of the hypothalamic-pituitary-thyroid (HPT) axis and energy homeostasis. To facilitate the study of these cells in neuroendocrine regulation, we will identify tanycyte specific genes by laser capture microdissection and microarray analysis to develop transgenic mice that express Cre recombinase specifically in tanycytes. These mice will be used to develop double transgenic mice in which tanycytes are selectively ablated or marked with GFP to allow isolation by fluorescence-activated cell sorting (FACS) for tissue culture.