A cluster of three long-range enhancers directs regional Shh expression in the epithelial linings
A cluster of three long-range enhancers directs regional Shh expression in the epithelial linings
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DOI：
10.1242/dev.032714
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发表时间：
2009-05-15
期刊：
影响因子：
4.6
通讯作者：
Shiroishi, Toshihiko
中科院分区：
文献类型：
--
作者：
Sagai, Tomoko;Amano, Takanori;Shiroishi, Toshihiko
sonic hedgehog （Shh）通路在小鼠口腔、呼吸和消化管上皮细胞的形态发生中起着不可或缺的作用。然而，到目前为止，还没有发现调节上皮内区域Shh表达的增强子。在这项研究中，通过比较哺乳动物和硬骨鱼的基因组序列，发现了三个新的保守非编码序列（cncs），它们聚集在小鼠Shh基因转录起始位点上游600 - 900kb的区域。这些cncs在口腔、咽、肺和肠道的上皮内层驱动区域转基因lacZ报告基因表达。总之，这些增强子概括了主要上皮衬里内的内源性Shh表达域。值得注意的是，三个cncs的基因组排列显示共线性，反映了上皮表达域沿前后体轴的顺序。结果表明，这三种cncs是上皮细胞壁特异性的远程Shh增强子，它们的作用将连续的上皮细胞壁划分为三个区域：外胚层来源的口腔、内胚层来源的咽部以及小鼠的呼吸和消化管。有针对性地缺失咽上皮特异性CNCS可导致咽部内源性Shh表达缺失，并导致软腭、会厌和类喉发育不全导致出生后死亡。因此，这种远程增强子对于咽器的形态发生是不可缺少的。
The sonic hedgehog (Shh) pathway plays indispensable roles in the morphogenesis of mouse epithelial linings of the oral cavity and respiratory and digestive tubes. However, no enhancers that regulate regional Shh expression within the epithelial linings have been identified so far. In this study, comparison of genomic sequences across mammalian species and teleost fishes revealed three novel conserved non-coding sequences (CNCSs) that cluster in a region 600 to 900 kb upstream of the transcriptional start site of the mouse Shh gene. These CNCSs drive regional transgenic lacZ reporter expression in the epithelial lining of the oral cavity, pharynx, lung and gut. Together, these enhancers recapitulate the endogenous Shh expression domain within the major epithelial linings. Notably, genomic arrangement of the three CNCSs shows co-linearity that mirrors the order of the epithelial expression domains along the anteroposterior body axis. The results suggest that the three CNCSs are epithelial lining-specific long-range Shh enhancers, and that their actions partition the continuous epithelial linings into three domains: ectoderm-derived oral cavity, endoderm-derived pharynx, and respiratory and digestive tubes of the mouse. Targeted deletion of the pharyngeal epithelium specific CNCS results in loss of endogenous Shh expression in the pharynx and postnatal lethality owing to hypoplasia of the soft palate, epiglottis and arytenoid. Thus, this long-range enhancer is indispensable for morphogenesis of the pharyngeal apparatus.