Nishizumi Hirofumi, Kumasaka Kouhei, Inoue Nobuko, Nakashima Ai, Sakano Hitoshi
Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Tokyo 113-0032, Japan.
Proc Natl Acad Sci U S A. 2007 Dec 11;104(50):20067-72. doi: 10.1073/pnas.0706544105. Epub 2007 Dec 5.
We have previously reported that a 2.1-kb homology (H) sequence, conserved between mouse and human, regulates the odorant receptor (OR) gene MOR28 in transgenic mice. Here, we narrowed down the essential sequences of the H to a core of 124 bp by using a transient expression system in zebrafish embryos. Transgenic experiments in mice demonstrated that the core-H sequence is sufficient to endow expression of the MOR28 minigene. Deletion and mutation analyses of the core-H region revealed two homeodomain sequences to be essential for the H enhancer activity. Targeted deletion of the core-H abolished expression of three proximal OR genes, MOR28, MOR10, and MOR83, in cis, indicating the presence of another locus control region/enhancer in the downstream region, that regulates four distal OR genes in the same MOR28 cluster. In the heterozygous mice, the H(-) phenotype of the mutant allele was not rescued by the wild-type H(+) allele in trans.
我们之前报道过，一段在小鼠和人类之间保守的2.1千碱基同源（H）序列，在转基因小鼠中调控嗅觉受体（OR）基因MOR28。在此，我们通过在斑马鱼胚胎中使用瞬时表达系统，将H的必需序列缩小至124碱基对的核心区域。小鼠转基因实验表明，核心H序列足以赋予MOR28小基因表达。对核心H区域的缺失和突变分析揭示，两个同源结构域序列对H增强子活性至关重要。核心H的靶向缺失顺式消除了三个近端OR基因MOR28、MOR10和MOR83的表达，表明在下游区域存在另一个位点控制区/增强子，其调控同一MOR28簇中的四个远端OR基因。在杂合小鼠中，突变等位基因的H（-）表型在反式中未被野生型H（+）等位基因挽救。
