REGULATION OF EQUINE CHORIONIC GONADOTROPIN EXPRESSION

灵长类和马科动物是唯一已知的哺乳动物合成绒毛膜 促性腺激素（CG）。 尽管人们对分子事件了解很多 人α亚单位基因的潜在胎盘特异性表达， 关于调节这些基因表达的机制知之甚少， 与人类LH β和CG β基因密切相关。 理解 控制马CG基因表达的机制更加滞后 因为这些基因还没有被克隆和完全鉴定。 马CG基因的进一步研究是必要的，因为有主要的 灵长类动物和马在生物学上的差异 垂体和胎盘促性腺激素包括：胎盘形成生物学， CG的结构和功能特性，结构关系 LH和CG之间，胎盘特异性表达的机制， α亚基基因，以及垂体LH分泌的垂体调节。 为了研究组织特异性表达和激素水平的机制， 调控编码eLH/CG的基因，我们提出三个具体目的：1） 定义胎盘特异性表达所需的顺式作用元件 马α亚基基因; 2）鉴定 eLH/CG β基因的激素调节;和3）构建转基因 小鼠和永生化细胞系，用于组织生理学研究， eLH/CG基因的特异性表达和激素调节。 各种 将使用的方法包括：PCR克隆，DNA-蛋白质分析， 马胎盘细胞原代培养物的转染，识别位点 克隆和在转基因小鼠中表达嵌合基因。 我们假设，一个复杂多样的顺式作用元件阵列， 反式作用因子将赋予组织特异性表达和激素 调节马LH/CG基因。 其中许多因素和因素 将可能不同于受调控表达 人类CG基因 此外，这些调节元件中的许多是 可能被其他表达靶向脑垂体的基因使用， 胎盘的 我们的目标是建立一个完整的生理模型， 评估大量紧密堆积的 促性腺激素基因启动子区发现的顺式作用元件 及其同源的反式作用因子。 我们将努力实现这一目标， 不仅通过识别启动子调控元件，而且通过开发， 同时，本发明还提供了一种转基因动物模型， 其生理意义。

Primates and equidae are the only mammals known to synthesize chorionic gonadotropin (CG). Although much is known about the molecular events underlying placenta-specific expression of the human alpha subunit gene, little is known about the mechanisms that regulate expression of the closely related human LHbeta and CGbeta genes. Understanding of the mechanisms governing expression of the equine CG genes lags even further behind as these genes that have yet to be cloned and fully characterized. Further study of the equine CG genes is warranted because there are major differences between primates and horses regarding the biology of their pituitary and placental gonadotropins including: biology of placentation, structural and functional properties of CG, structural relationships between LH and CG, mechanisms underlying placenta-specific expression of the alpha subunit gene, and hormonally regulated secretion of pituitary LH. To study the mechanisms underlying tissue-specific expression and hormonal regulation of genes encoding eLH/CG we propose three Specific Aims: 1) define the cis-acting elements required for placenta-specific expression of the horse alpha subunit gene; 2) identify regulatory elements required for hormonal regulation of the eLH/CGbeta gene; and 3) construct transgenic mice and immortalized cell lines for physiological studies on tissue- specific expression and hormonal regulation of the eLH/CG genes. A variety of approaches will be used including: PCR cloning, DNA-protein analyses, transfection of primary cultures of horse placental cells, recognition site cloning, and expression of chimeric genes in transgenic mice. We postulate that a complex and diverse array of cis-acting elements and trans-acting factors will confer tissue-specific expression and hormonal regulation to the horse LH/CG genes. Many of these elements and factors will likely be different than those required for regulated expression of the human CG genes. Furthermore, many of these regulatory elements are probably used by other genes whose expression is targeted to pituitary or placental. Our goal is to develop a complete physiological model to evaluate the biological significance of the large number of tightly packed cis-acting elements found in the promoter region of the gonadotropin genes and their cognate trans-acting factors. We will approach this goal not only by identifying promoter-regulatory elements, but also by developing, simultaneously, a transgenic animal model which can be used to evaluate their physiological significance.