XACT: X active specific transcript
XACT is a 251.8-kb transcription unit(112,983,323–113,235,148 bp) and it is located on chromosome Xq23 between the protein-coding genes AMOT and HTR2C . XACT is polyadenylated and belongs to intergenic lncRNA group .
XACT is mostly nuclear .
XACT is involved in the control of XCI (X-chromosome inactivation) initiation in human . XACT is expressed from and coats the active X chromosome specifically in human pluripotent cells. In the absence of XIST, XACT is expressed from both X chromosomes in human but not in mouse, suggesting a unique role for XACT in the control of human XCI initiation .
Although the organization of the genomic region encompassing AMOT and HTR2C is well conserved in placental mammals and marsupials, the sequence between these two genes shows moderate conservation, with several conserved blocks present in placental mammals but not marsupials. The LTR (long terminal repeat) that corresponds to the 5' end of XACT is conserved in chimpanzees but not macaques or more distally related species, suggesting that the insertion of these LTR elements is a very recent event .
No XACT-like transcript expression is detected in mouse, which indicates that XACT might not be conserved in mouse .
XACT is expressed in active X chromosome in human but not in mouse, and the expression of XACT is restricted to pluripotent and early differentiating cells in human .
>gi|784642207|ref|NR_131204.1| Homo sapiens X active specific transcript (non-protein coding) (XACT), long non-coding RNA
Labs working on this lncRNA
- University Paris Diderot, Sorbonne Paris City, Epigenetics and Cell Fate, Paris, France