Genes flanking Xist in mouse and human are separated on the X chromosome in American marsupials.

Autor: Alexander Shevchenko, Irina Zakharova, Eugeny Elisaphenko, Nicolay Kolesnikov, Siobhan Whitehead, Christine Bird, Mark Ross, Jennifer Weidman, Randy Jirtle, Tatiana Karamysheva, Nicolay Rubtsov, John VandeBerg, Nina Mazurok, Tatyana Nesterova, Neil Brockdorff
Zdroj: Chromosome Research; Feb2007, Vol. 15 Issue 2, p127-136, 10p
Abstrakt: Abstract??X inactivation, the transcriptional silencing of one of the two X chromosomes in female mammals, achieves dosage compensation of X-linked genes relative to XY males. In eutherian mammals X inactivation is regulated by the X-inactive specific transcript (Xist), acis-acting non-coding RNA that triggers silencing of the chromosome from which it is transcribed. Marsupial mammals also undergo X inactivation but the mechanism is relatively poorly understood. We set out to analyse the X chromosome inMonodelphis domesticaandDidelphis virginiana, focusing on characterizing the interval defined by theChic1andSlc16a2genes that in eutherians flank theXistlocus. The synteny of this region is retained on chicken chromosome 4 where other loci belonging to the evolutionarily ancient stratum of the human X chromosome, the so-called X conserved region (XCR), are also located. We show that in bothM. domesticaandD. virginianaan evolutionary breakpoint has separated theChic1andSlc16a2loci. Detailed analysis of opossum genomic sequences revealed linkage ofChic1with theLnx3gene, recently proposed to be the evolutionary precursor ofXist, andFip1, the evolutionary precursor ofTsx, a gene located immediately downstream ofXistin eutherians. We discuss these findings in relation to the evolution ofXistand X inactivation in mammals. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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