Molecular basis of odorant receptor genes expression and axonal projection of olfactory sensory neurons using zebrafish

我们以前曾报道过一个2.1kb的同源序列（H），在小鼠和人之间是保守的，在转基因小鼠中调节气味受体（OR）基因MOR 28。在这里，我们缩小了H的核心124 bp的基本序列，在斑马鱼胚胎中使用瞬时表达系统。小鼠中的转基因实验证明，核心-H序列足以赋予M0 R 28小基因的表达。核心-H区域的缺失和突变分析揭示了两个同源结构域序列是H增强子活性所必需的。核心-H的靶向缺失废除了顺式的三个近端OR基因MOR 28、MOR 10和MOR 83的表达，表明下游区域存在另一个LCR/增强子，其调节同一MOR 28簇中的四个远端OR基因。在杂合子小鼠中，突变等位基因的H^-表型不能被野生型H^+等位基因反式挽救。

We have previously reported a 2.1kb 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 124bp, 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 LCR/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.