title: Localization and expression analysis of a novel conserved brain expressed transcript, Brx/BRX, lying within the Xic/XIC candidate region.
abstract: The X inactivation center candidate region (Xic/XIC in mouse and human) is poorly characterized for the presence of transcription units. Only two conserved genes have been isolated to date, Xist/XIST and Cdx4/CDX4. The other known gene lying within this region, Tsx, has been identified so far only in rodents by analyzing the complete genomic sequence of a 94-kb region distal to Xist. Here, we report the characterization of an additional gene lying within this 94-kb sequenced region. Brx, for Brain X-linked gene, is a rare transcript preferentially expressed in the brain. It is normally X-inactivated in the mouse. Localisation of BRX, its human homolog has shown the gene to be located within the orthologous but inverted human CDX4-XIST segment. These results suggest that the gene order of the region encompassing the Cdx4-Xist interval in the mouse is similar in human. Comparison of the Xist-Brx and Brx-Cdx4 regions in mouse and human indicates that these intervals are three times longer in human than in mouse. BRX is a new potential candidate for one of the X-linked mental retardation syndromes mapped within the pericentromeric region of the human X Chromosome (Chr).
authors.affiliation: CNRS UA 1968, Génétique Moléculaire Murine, Institut Pasteur, Paris, France.
authors.forename: M C
authors.initials: MC
authors.lastname: Simmler
authors.forename: E
authors.initials: E
authors.lastname: Heard
authors.forename: C
authors.initials: C
authors.lastname: Rougeulle
authors.forename: C
authors.initials: C
authors.lastname: Cruaud
authors.forename: J
authors.initials: J
authors.lastname: Weissenbach
authors.forename: P
authors.initials: P
authors.lastname: Avner
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry / Q000235:genetics*; D002874:Chromosome Mapping; D018244:Chromosomes, Artificial, Yeast; D017124:Conserved Sequence; D004247:DNA / Q000302:isolation & purification; D018076:DNA, Complementary; D015870:Gene Expression / Q000235:genetics*; D008040:Genetic Linkage; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012313:RNA / Q000302:isolation & purification; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014960:X Chromosome / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D012313:RNA; D004247:DNA