REGULATION OF EQUINE CHORIONIC GONADOTROPIN EXPRESSION

灵长类动物和马科动物是已知的唯一能合成绒毛膜的哺乳动物 促性腺激素(CG)。尽管人们对分子事件知道得很多 人类阿尔法亚单位基因的胎盘特异性表达， 人们对调控该基因表达的机制知之甚少。 密切相关的人类LHbeta和CGbeta基因。对这一概念的理解 控制马CG基因表达的机制甚至更滞后 在这些基因背后，还没有被克隆和充分表征。 有必要对马的CG基因进行进一步的研究，因为有主要的 灵长类动物和马之间在生物学上的差异 脑下垂体和胎盘促性腺激素包括：胎盘生物学， CG的结构和功能性质、结构关系 促黄体生成素和促性腺激素促性腺激素释放激素的作用机制 α亚单位基因，以及荷尔蒙调节的垂体促黄体生成素的分泌。 研究组织特异性表达和荷尔蒙的机制 编码ELH/CG基因的调控我们提出了三个具体目标：1) 定义胎盘特异性表达所需的顺式作用元件 马的阿尔法亚单位基因；2)确定所需的调控元件 Elh/CGbeta基因的激素调节；3)构建转基因 用于组织生理学研究的小鼠和永生化细胞系- ELH/CG基因的特异性表达和激素调节。品种繁多 将使用的方法包括：聚合酶链式反应克隆、DNA蛋白质分析、 转染马胎盘细胞原代培养细胞的识别位点 嵌合基因在转基因小鼠中的克隆和表达。 我们假设一系列复杂多样的顺式作用元素和 反式作用因子将赋予组织特异性表达和激素 对马的促黄体生成素/卵泡刺激素基因的调控。这些要素和因素中的许多 可能不同于受调控的表达 人类的CG基因。此外，这些监管要素中的许多都是 可能被其他基因使用，这些基因的表达是针对脑下垂体或 胎盘。我们的目标是开发一个完整的生理模型来 评估大量紧密堆积的生物意义 促性腺激素基因启动子区域发现的顺式作用元件 以及它们的同源反式作用因素。我们将不会接近这一目标 不仅通过识别启动子调控元件，而且通过开发， 同时，一种可用于评估的转基因动物模型 它们的生理意义。

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.