RENIN-ANGIOTENSIN SYSTEM

最近的数据表明，为了正确的胚胎发育， 多肽必须以适当的时间和数量的方式表达。 也有人提出，一些机制和蛋白质 参与胚胎发生的可能在成人中重复，在 组织修复和血管生成。我们实验室的最新数据显示 提示Ang II和AT2受体可能就是这样的蛋白。我们有 最近研究表明，AT2受体在血管间充质中表达。 发育中的鼠胎。它们非常丰富，但只是短暂的 在胎儿发育过程中表达，达到最大丰度 胚胎19-21天，出生后迅速减少。我们的假设 Ang II通过其AT2受体发挥重要作用 在胎儿的间质增殖和/或分化中。这个 本提案的目的是确定与增长相关的行动是否 Ang II是通过AT2受体介导的，它决定了什么是 血管紧张素Ⅱ在正常大鼠胚胎发育中的生理作用三 主要问题将得到解决。1)Ang II是正常所必需的吗 胚胎/胎儿发育，如果是的话，是否存在这种多肽 在分化/成熟的特定阶段是关键的？2)和 II在间充质细胞增殖和/或分化中的作用 Ang II是如何调节其影响的(S)？第二个信使是什么？ 系统？血管紧张素转换酶II是否通过增强和/或诱导 其他生长因子的合成？具体地说，我们将确定何时 AT2受体在胚胎发育过程中首次表达 受体测定及血管紧张素I、II、III相对丰度的测定 与这些受体结合的多肽。在体内和体外使用 动物模型，我们将检测AT2受体拮抗剂的作用 (PD123177和CGP 42112A)对胚胎发生有影响。这些敌手将会是 在整个怀孕期间不同时间给怀孕的大鼠注射 或者直接添加到体外生长的胚胎中。这第二个范例 消除拮抗剂对胎盘可能产生的混杂作用 发行量。胎儿的生长和发育将通过以下方式进行评估 测量大小、重量、总DNA、蛋白质含量和毛发 形态缺陷。直接评价血管紧张素转换酶II和血管紧张素转换酶2的作用 受体阻断对间充质细胞的增殖/分化有影响， 我们将同时使用原代间充质培养和畸胎癌细胞。 分析增殖、DNA合成、蛋白质合成和起病的系列 在初级培养物中的衰老。最后，我们将尝试确定 血管紧张素转换酶II如何通过研究最可能的信号转导来调节其影响 机制(S)与AT2受体相连。

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.