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Murine hoxd4 expression in the CNS requires multiple elements including a retinoic acid response element
F Zhang1, E Nagy Kovács, M S Featherstone
1McGill Cancer Centre, McGill University, 3655 Promenade Sir William Osler, Québec H3G 1Y6, Montréal, Canada.
Mechanisms of Development
|August 15, 2000
Summary
Researchers found a retinoic acid response element (RARE) in the Hoxd4 neural enhancer. This RARE controls gene expression initiation, maintenance, and response to retinoic acid (RA) in neurectoderm development.
Area of Science:
- Developmental Biology
- Gene Regulation
- Neuroscience
Background:
- The Hoxd4 gene plays a crucial role in embryonic development.
- Neural enhancers regulate gene expression patterns during neurodevelopment.
- Retinoic acid (RA) is a signaling molecule critical for embryonic patterning.
Purpose of the Study:
- To identify and characterize regulatory elements within the Hoxd4 neural enhancer.
- To investigate the role of a specific retinoic acid response element (RARE) in Hoxd4 gene regulation.
- To understand how mutations in this enhancer affect gene expression in neurectoderm.
Main Methods:
- Identification of a RARE within the neural enhancer 3' to the Hoxd4 gene.
- Transgene expression analysis in neurectoderm with and without RA treatment.
- Site-directed mutagenesis of the TTTTCTG sequence downstream of the RARE.
- In vitro binding assays using human CDX1 protein.
Main Results:
- The identified RARE is essential for initiating and maintaining Hoxd4 transgene expression in neurectoderm.
- RA treatment leads to full anteriorized expression, dependent on the RARE.
- Mutating the TTTTCTG sequence posteriorizes transgene activity but does not affect RA response.
- Human CDX1 protein did not bind to the TTTTCTG motif in vitro.
- Multiple regulatory elements contribute to the overall function of the Hoxd4 neural enhancer.
Conclusions:
- A novel RARE within the Hoxd4 neural enhancer is critical for regulating gene expression during neurodevelopment.
- The TTTTCTG motif, despite its resemblance to a CDX binding site, does not appear to be functionally recognized by CDX1 in this context.
- The Hoxd4 neural enhancer is a complex regulatory unit composed of multiple functional elements, highlighting intricate control mechanisms in gene expression.