BIOLOGY OF MAMMALIAN HOMEODOMAIN PROTEINS

大多数蛋白质的功能障碍，干扰胚胎发育的苍蝇 共有一段由60个氨基酸组成的称为同源结构域的特征。 哺乳动物同样表达含有同源结构域的蛋白质。基于其 核定位，它们与特定DNA序列结合的能力， 以及它们与一些特征明确的转录因子的关系， 这表明同源结构域蛋白参与调节基因 哺乳动物的表达。在我们努力确定 哺乳动物同源结构域蛋白，我们已经克隆，测序，并研究了 表达一种称为Hox 1-3的鼠足类基因， 为了测试体内生物功能，我们最近培育了转基因小鼠， 其含有单个或多个（最多25个）诱导型 Hox 1.3转基因。为了控制异位Hox 1.3表达水平，我们 使用可诱导的小鼠Mxl调节元件作为我们的转基因 启动子，该启动子允许Hox 1-3在细胞中的有意的普遍表达。 其诱导物（干扰素或双链RNA）的存在。下 生理条件下，即在没有诱导的情况下，小鼠 表达其内源性Hox 1.3基因，并且在这些器官中， 北方分析，发现很少或没有可检测的转基因RNA。 在没有转基因诱导的情况下，这些小鼠看起来健康。转基因后 用干扰素或双链RNA诱导，小鼠开始 表达高水平的转基因RNA和蛋白质， 机关此外，静脉注射干扰素， 在子宫内携带转基因胚胎的非转基因雌性导致 我们转基因的胚胎诱导我们的首要目标是 确定在胚胎或出生后发育期间是否以及何时 异位表达Hox 1.3有影响，然后在体内使用这个 工具，以确定内源性基因的上调或下调， Hox 1.3

Most of the proteins whose dysfunction disturbs embryogenesis of the fly share a characteristic stretch of 60 amino acids called the homeodomain. Mammals likewise express homeodomain-containing proteins. Based on their nuclear localization, their capacity to bind to specific DNA sequences, and their relation to some well-characterized transcription factors, it is suggested that homeodomain proteins are involved in regulating gene expression in mammals. In our effort to determine the function of mammalian homeodomain proteins, we have cloned, sequenced, and studied the expression of one of the murine Antennapedia class genes known as Hox 1-3- To test in vivo biofunction, we have recently generated transgenic mice that contain either a single or multiple (up to 25) copies of an inducible Hox 1.3 transgene. To control the levels of ectopic Hox 1.3 expression, we have used the inducible mouse Mxl regulatory element as our transgene promoter which allows the deliberate ubiquitous expression of Hox 1-3 in the presence of its inducers (interferon or double-stranded RNA). Under physiologic conditions, that is, in the absence of induction, the mice express their endogenous Hox 1.3 gene, and in those organs tested by Northern analysis, little or no detectable transgene RNA was found. In the absence of transgene induction, these mice appear healthy. After transgene induction with either interferon or double-stranded RNA, the mice start to express high levels of transgenic RNA and protein in many different organs. In addition, intravenous injection of interferon into non-transgenic females that carry in utero transgenic embryos results in the fetal induction of our transgene. Our primary goal is to first identify if and when during embryonic or postnatal development does ectopic expression of Hox 1.3 have an effect, and then to use this in vivo tool to identify endogenous genes that are either up- or down-regulated by Hox 1.3.