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Localization and expression analysis of a novel conserved brain expressed transcript, Brx/BRX, lying within the
M C Simmler1, E Heard, C Rougeulle
1CNRS UA 1968, Génétique Moléculaire Murine, Institut Pasteur, Paris, France.
Summary
Researchers identified a new gene, Brain X-linked gene (Brx), in the mouse X inactivation center. This gene is normally inactivated on the X chromosome and may be linked to X-linked mental retardation syndromes.
Area of Science:
- Genetics and Genomics
- Developmental Biology
- Human Disease Genetics
Background:
- The X inactivation center (Xic) is crucial for dosage compensation but remains poorly understood regarding its gene content.
- Only Xist/XIST and Cdx4/CDX4 were known conserved genes within the Xic; Tsx was identified only in rodents.
Purpose of the Study:
- To characterize a novel gene within a 94-kb region distal to Xist in the mouse Xic.
- To investigate the evolutionary conservation and potential role of this new gene in human X-linked disorders.
Main Methods:
- Genomic sequencing and transcript analysis to identify and characterize the new gene.
- Comparative mapping of the gene and its human homolog within the Xic region.
- Analysis of gene expression patterns and X-inactivation status.
Main Results:
- A new gene, Brain X-linked gene (Brx), was identified, showing rare transcripts predominantly in the brain.
- Brx is subject to normal X inactivation in mice.
- The human homolog of BRX is located within the orthologous CDX4-XIST segment, suggesting conserved gene order but larger intergenic regions in humans.
Conclusions:
- Brx represents a newly identified gene within the Xic, conserved across species.
- The comparative genomic analysis reveals significant differences in region size between mouse and human Xic.
- BRX is a potential candidate gene for X-linked mental retardation syndromes associated with the human X chromosome pericentromeric region.