SEX SPECIFIC HEPATIC FUNCTION IN LIZARDS

卵黄发生，卵黄脂蛋白合成的过程 由肝脏和积累在发展中的卵母细胞，是 对于非哺乳动物的成功繁殖至关重要 脊椎动物这一过程被认为是一个很好的模型系统， 性分化肝脏蛋白质合成激素调节 在脊椎动物中。因此，本建议的主要目标是 了解荷尔蒙的相互作用，以表达女性特有的 蜥蜴慢性圈养应激下的肝脏基因 美丽的安诺利斯最重要的是心血管疾病 以及人类生殖功能障碍的发生与 伴性肝蛋白质代谢此外，它还被 表明暴露在压力下会引发这些功能障碍。 因此，研究卵黄蛋白原基因的表达调控， 可以为这些疾病的发生和治疗提供重要的见解， 肝脏疾病，没有实验模型， 人类 在以前的研究中，我们已经表明， 在圈养压力下明显的生殖退化，包括 肝脏合成卵黄蛋白原的急剧减少 VTG mRNA水平降低，卵泡发育停止， 生长和排卵、卵泡闭锁增加和退化 输卵管腺的分泌圈养雌性蜥蜴的雌激素治疗 大大提高了生殖活动，并防止或逆转 圈养对卵黄蛋白原合成和分泌的负面影响 由肝。由于压力反应与 垂体-肾上腺轴激素水平的改变，我们建议 圈养的有害影响在雌性特定的 肝功能是通过糖皮质激素水平的改变来调节的 这反过来又会导致雌激素依赖性 基因.我们的研究计划主要考虑了三种机制：1） 雌激素水平降低，2）肝脏雌激素减少 受体（HER）水平/活性，和/或3）雌激素竞争性 基因调控位点的相互作用。因此，我们建议：（1） 分析VTG基因在圈养条件下的表达机制， 通过测定VTG蛋白质合成、mRNA水平和 转录率，并评估雌激素的作用， 肝脏雌激素受体的活性/水平。2)表征 多激素相互作用参与VTG基因表达， 压力和不同激素治疗的研究。3)到 启动Anolis VTG基因的结构研究，包括 使用同源cDNA探针分离5'调控区 最近在我们实验室克隆出来的。这将导致未来的分析 受体复合物的相互作用，在调节 网站.这项研究计划将提供丰富的环境， 生物医学研究的学生培训。

Vitellogenesis, the process whereby yolk lipoproteins are synthesized by the liver and accumulated in the developing oocyte, is of fundamental importance for the successful reproduction of non-mammalian vertebrates. This process is considered an excellent model system for the hormonal regulation of sex-differentiated hepatic protein synthesis in vertebrates. Accordingly, the main objective of this proposal is to understand the hormonal interplay for the expression of female specific hepatic genes under the chronic stress of captivity in the lizard Anolis pulchellus. Of major relevance is that cardiovascular disease and reproductive malfunctioning in humans have been related to altered sex-linked hepatic protein metabolism. In addition, it has also been shown that exposure to stress triggers the onset of these malfunctions. Therefore, studies of the regulation of vitellogenin gene expression could provide important insights in the genesis and treatment of these hepatic diseases for which no experimental models are available in humans. In previous studies we have shown that anoline lizards undergo pronounced reproductive regression under captivity stress, including a drastic decrease of the synthesis of vitellogenin by the liver paralleled to a decrease in VTG mRNA levels, cessation of follicular growth and ovulation, increased follicular atresia, and degeneration of the oviductal glands. Estrogen therapy to captive female lizards greatly improves reproductive activity and prevents or reverts the negative effect of captivity on vitellogenin synthesis and secretion by the liver. Since stress responses have been related to the alteration of hormone levels of the pituitary-adrenal axis, we suggest that the detrimental effects of captivity evoked in female specific liver functions are mediated through altered levels of glucocorticoids which, in turn, result in the faulty expression of estrogen dependent genes. Three main mechanisms are considered in our research plan: 1) reduction of estrogen levels, 2) reduction of the hepatic estrogen receptor (HER) levels/activity, and/or 3) estrogen competitive interactions at the gene regulatory site. Therefore, we propose: 1) To analyze the mechanisms of VTG gene expression during captivity at the molecular level by determining VTG protein synthesis, mRNA levels and transcriptional rates and evaluate the effect of estrogen and the activity/levels of the hepatic estrogen receptor. 2) To characterize the multihormonal interplay involved in VTG gene expression under stress and different hormonal treatments in vivo and in vitro. 3) To initiate structural studies of the Anolis VTG genes including the isolation of the 5' regulatory regions using homologous cDNA probes recently cloned in our laboratory. This will lead to future analysis of the interaction of hormone-receptor complexes at the regulatory sites. This research proposal will provide a rich environment for student training in biomedical research.