RENIN-ANGIOTENSIN SYSTEM

肾素-血管紧张素系统

基本信息

批准号：
3331070
负责人：
JUDITH E KALINYAK
金额：
$ 14.29万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
依托单位国家：
美国
项目类别：
财政年份：
1992
资助国家：
美国
起止时间：
1992-07-01 至 1995-07-31
项目状态：
已结题

项目摘要

Recent data suggests that for correct embryonic development multiple peptides must be expressed in a proper temporal and quantitative fashion. It has also been proposed that some of the mechanisms and proteins involved in embryogenesis may be reiterated in the adult, functioning in tissue repair and angiogenesis. Recent data from our laboratory would suggest that Ang II and the AT2 receptor may be such proteins. We have recently shown that AT2 receptors are expressed in the mesenchyme of the developing rat fetus. They are highly abundant but only transiently expressed during fetal development, reaching maximal abundance by embryonic day 19-21, and rapidly decreasing after birth. Our hypothesis is that Ang II, acting through its AT2 receptor, plays an important role in mesenchymal proliferation and/or differentiation in the fetus. The purpose of this proposal is to determine if the growth related actions of Ang II are mediated through the AT2 receptor and determine what is the physiologic function of Ang II in normal rat fetal development. Three major questions will be addressed. 1) Is Ang II necessary for normal embryonic/fetal development and, if so, is the presence of this peptide critical at a specific stage of differentiation/maturation? 2) Does Ang II function in mesenchymal cell proliferation and/or differentiation? 3) How does Ang II mediate its effect(s)? What is the second messenger system? Does Ang II function by potentiating and/or inducing the synthesis of other growth factors? Specifically, we will determine when AT2 receptors are first expressed during embryogenesis using an in situ receptor assay and determine the relative abundance of Ang I, II, and III peptides bound to these receptors. Using both in vivo and in vitro animal models, we will examine the effects AT2 receptor antagonists (PD123177 & CGP 42112A) have on embryogenesis. These antagonists will be administered to pregnant rats at varying times throughout the pregnancy or added directly to embryos growing in vitro. This second paradigm removes the confounding effects the antagonists may have on placental circulation. The fetuses will be evaluated for growth and development by measuring size, weight, total DNA, and protein content and gross morphologic defects. To directly evaluate the effects of Ang II and AT2 receptor blockade has on mesenchymal cell proliferation/differentiation, we will use both primary mesenchymal cultures and teratocarcinoma cell lines analyzing proliferation, DNA synthesis, protein synthesis and onset of senescence in the primary cultures. Finally, we will try to determine how Ang II mediates its effects by examining the most likely signaling mechanism(s) to be linked to the AT2 receptor.

最近的数据表明，对于正确的胚胎开发多重肽必须以适当的时间和定量方式表达。还提出了一些机制和蛋白质参与胚胎发生的成人可能会重申组织修复和血管生成。我们实验室的最新数据将表明ANG II和AT2受体可以是这样的蛋白质。我们有最近表明，AT2受体在间隙中表达发展大鼠胎儿。它们高度丰富，但只有短暂在胎儿发育期间表达，达到最大的丰度胚胎第19-21天，出生后迅速下降。我们的假设是通过其AT2受体起作用的Ang II起重要作用在胎儿的间充质增殖和/或分化中。这该提案的目的是确定与增长相关的行动是否与 ANG II通过AT2受体介导，并确定什么是 ANG II在正常大鼠胎儿发育中的生理功能。三将解决主要问题。 1）正常需要ANG II 胚胎/胎儿发育，如果是的，则是这种肽的存在在分化/成熟的特定阶段至关重要？ 2）ang II在间充质细胞增殖和/或分化中的功能？ 3） Ang II如何介导其效果？什么是第二个使者系统？ Ang II是否通过增强和/或诱导其他生长因素的综合？具体来说，我们将确定何时 AT2受体首先在胚胎发生期间使用原位表达受体分析并确定ANG I，II和III的相对丰度与这些受体结合的肽。同时使用体内和体外动物模型，我们将检查AT2受体拮抗剂的影响（PD123177和CGP 42112a）具有胚胎发生。这些对手会在整个怀孕期间在不同的时间内给孕妇大鼠施用或直接添加到体外生长的胚胎中。第二个范式消除拮抗剂可能对胎盘产生的混杂影响循环。胎儿将通过测量尺寸，重量，总DNA和蛋白质含量以及总含量形态缺陷。直接评估ANG II和AT2的影响受体阻滞具有间充质细胞增殖/分化，我们将同时使用原发性间质培养物和畸胎瘤细胞分析增殖，DNA合成，蛋白质合成和发作的线条初级文化中的衰老。最后，我们将尝试确定 Ang II如何通过检查最可能的信号传导来介导其效果与AT2受体有关的机制。