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Published on: October 19, 2013
Initiation of cyp26a1 Expression in the Zebrafish Anterior Neural Plate by a Novel Cis-Acting Element
Chunhong Chen1,2,3, Aline Stedman1,2,3, Emmanuelle Havis1,2,3
1CNRS, UMR 7622, Paris, France.
Abstract:
Early patterning of the vertebrate neural plate involves a complex hierarchy of inductive interactions orchestrated by signalling molecules and their antagonists. The morphogen retinoic acid, together with the Cyp26 enzymes which degrade it, play a central role in this process. The cyp26a1 gene expressed in the anterior neural plate thus contributes to the fine modulation of the rostrocaudal retinoic acid gradient. Despite this important role of cyp26a1 in early brain formation, the mechanisms that control its expression in the anterior neural plate are totally unknown. Here, we present the isolation of a 310-base-pair DNA element adjacent to cyp26a1 promoter, displaying enhancer activity restricted to the anterior neural plate of the zebrafish gastrula. We show that unlike that of cyp26a1, expression driven by this cyp26a1 anterior neural plate element (cANE) is independent of retinoic acid. Through deletion analysis, we identify a 12-nucleotide motif essential for cANE activity. A consensus bipartite binding site for SoxB:Oct transcription factors overlaps with this motif. Mutational analysis suggests that SoxB binding is essential for its activity. We discuss the contribution of this study to the elucidation of the regulatory hierarchy involved in early neural plate patterning.
Insights
Researchers identified a novel DNA element, the cyp26a1 anterior neural plate element (cANE), crucial for regulating gene expression in the early zebrafish brain. This element
Area of Science:
- Developmental biology
- Molecular genetics
- Neuroscience
Background:
- Vertebrate neural plate patterning relies on complex signaling pathways.
- Retinoic acid and its degrading enzymes (Cyp26) are key morphogens in early brain development.
- The precise regulation of cyp26a1 in the anterior neural plate remains unclear.
Purpose of the Study:
- To investigate the regulatory mechanisms controlling cyp26a1 expression in the anterior neural plate.
- To identify DNA elements responsible for anterior neural plate-specific gene expression.
- To elucidate the molecular factors involved in early neural patterning.
Main Methods:
- Isolation and characterization of a novel DNA enhancer element (cANE) adjacent to the cyp26a1 promoter.
- Reporter gene assays to assess enhancer activity in zebrafish gastrula.
- Deletion analysis to identify critical functional motifs within cANE.
- Mutational analysis to determine the role of transcription factor binding sites.
Main Results:
- A 310-bp DNA element (cANE) exhibits enhancer activity specifically in the anterior neural plate of zebrafish embryos.
- cANE-driven expression is independent of retinoic acid, unlike endogenous cyp26a1.
- A 12-nucleotide motif within cANE is essential for its activity.
- This motif contains a binding site for SoxB:Oct transcription factors, with SoxB binding being critical for cANE function.
Conclusions:
- A novel enhancer, cANE, regulates cyp26a1 expression in the anterior neural plate.
- SoxB:Oct transcription factors play a crucial role in mediating cANE activity.
- This finding contributes to understanding the regulatory hierarchy governing early neural plate patterning.
