Functional analysis of α1 adrenergic receptor using mutant mice generated by the gene targeting.

α1-ARs在调节多种生理过程中发挥关键作用。越来越多的证据表明，这些生理反应是由多个受体亚型的结构同源性。分子克隆鉴定出3种不同的α1-AR亚型（α1a，α1b，α1d）。在α1-AR亚型中，α1D-AR的功能仍然不确定，尽管它在各种组织中表达。为了研究α1D-AR的生理作用和结构-功能关系，我们克隆并鉴定了小鼠α1D-AR的基因。以大鼠α1D-AR cDNA为探针，从小鼠基因组文库中克隆小鼠α1D-AR基因。它由两个外显子和一个内含子组成，内含子长度超过5个碱基，并中断了第六跨膜结构域的编码区。利用这些信息和DNA片段，构建了用于破坏小鼠基因的靶向载体，并转染ES细胞。分离出几个阳性克隆，用于囊胚注射。生成α1D-AR纯合子突变小鼠。他们看起来很正常，并且被证明可以生育。这些小鼠可用于分析α1-AR之间的相互作用。

α1-ARs play critical roles in the regulation of a variety of physiological processes. Increasing evidence suggests that these physiological responses are regulated by multiple receptor subtypes that are structurally homologous. Molecular cloning identified three distinct cDNA encoding α1-AR subtypes (α1a, α1b, α1d). Among the α1-AR subtypes, the function of the α1D-AR remains uncertain, although it is expressed in various tissues. In order to examine the physiological role and the structure-function relationship, we cloned and characterized a gene for the murine α1D-AR. Using a rat α1D-AR cDNA as a probe, the gene for the murine α1D-AR gene is cloned from murine genomic libraries. It consists of two exons and an intron which is over 5 kilobases and interrupts the coding region of the sixth trasmembrane domain. With these information and DNA fragments, a targeting vector for disrupting the gene in mice was constructed and transfected into ES cells. Several positive clones were isolated which were used for blastocyteinjenction. Homozygous mutant mice for α1D-AR were generated. They look normal and proved to be fertile. These mice should be useful for analysis for interaction among α1-ARs.