| First Author | Park E | Year | 2017 |
| Journal | Mol Cells | Volume | 40 |
| Issue | 6 | Pages | 426-433 |
| PubMed ID | 28614915 | Mgi Jnum | J:334040 |
| Mgi Id | MGI:6765157 | Doi | 10.14348/molcells.2017.0052 |
| Citation | Park E, et al. (2017) Identification of an Enhancer Critical for the ephirn-A5 Gene Expression in the Posterior Region of the Mesencephalon. Mol Cells 40(6):426-433 |
| abstractText | Ephrin-A5 has been implicated in the regulation of brain morphogenesis and axon pathfinding. In this study, we used bacterial homologous recombination to express a LacZ reporter in various ephrin-A5 BAC clones to identify elements that regulate ephrin-A5 gene expression during mesencephalon development. We found that there is mesencephalon-specific enhancer activity localized to a specific +25.0 kb to +30.5 kb genomic region in the first intron of ephrin-A5. Further comparative genomic analysis indicated that two evolutionary conserved regions, ECR1 and ECR2, were present within this 5.5 kb region. Deletion of ECR1 from the enhancer resulted in disrupted mesencephalon-specific enhancer activity in transgenic embryos. We also found a consensus binding site for basic helix-loop-helix (bHLH) transcription factors (TFs) in a highly conserved region at the 3'-end of ECR1. We further demonstrated that specific deletion of the bHLH TF binding site abrogated the mesencephalon-specific enhancer activity in transgenic embryos. Finally, both electrophoretic mobility shift assay and luciferase-based transactivation assay revealed that the transcription factor Ascl1 bound the bHLH consensus binding site in the mesencephalon-specific ephrin-A5 enhancer in vitro. Together, these results suggest that the bHLH TF binding site in ECR1 is involved in the positive regulation of ephrin-A5 gene expression during the development of the mesencephalon. |
