Kim Yujin, Park Eunjeong, Park Soochul
Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Korea.
Mol Cells. 2015 Nov;38(11):1007-12. doi: 10.14348/molcells.2015.0221. Epub 2015 Nov 4.
EphA7 is a key molecule in regulating the development of the dien- and mesencephalon. To get insight into the mechanism of how EphA7 gene expression is regulated during the dorsal specification of the dien- and mesencephalon, we investigated the cis-acting regulatory sequence driving EphA7 to the dorsal midline of the dien- and mesencephalon. Transgenic LacZ reporter analysis, using overlapping EphA7 BACs, was used to narrow down the dorsal midline-specific enhancer, revealing the 25.3 kb genomic region as the enhancer candidate. Strikingly, this genomic DNA was located far downstream of the EphA7 transcription start site, +302.6 kb to +327.9 kb. Further enhancer mapping, using comparative genomic analysis and transgenic methods, showed that the 187 bp genomic DNA alone, approximately 305 kb downstream of the EphA7 transcription start site, was sufficient to act as the dorsal midline-specific enhancer of EphA7. Importantly, our results indicate that the 187 bp dorsal midline-specific enhancer is critically regulated by homeobox transcription factors during the development of the dien- and mesencephalon.
EphA7是调节间脑和中脑发育的关键分子。为深入了解在间脑和中脑背侧特化过程中EphA7基因表达是如何被调控的机制，我们研究了驱动EphA7表达至间脑和中脑背中线的顺式作用调控序列。利用重叠的EphA7细菌人工染色体（BAC）进行转基因LacZ报告基因分析，以缩小背中线特异性增强子的范围，结果显示25.3 kb的基因组区域为增强子候选区域。令人惊讶的是，该基因组DNA位于EphA7转录起始位点下游很远的位置，即从+302.6 kb至+327.9 kb。通过比较基因组分析和转基因方法进行的进一步增强子定位表明，仅187 bp的基因组DNA，位于EphA7转录起始位点下游约305 kb处，就足以作为EphA7的背中线特异性增强子。重要的是，我们的结果表明，在间脑和中脑发育过程中，187 bp的背中线特异性增强子受到同源框转录因子的严格调控。
