MAYEX is an old long noncoding RNA recruited for X chromosome dosage compensation in a reptile.
Mariela TenorioSamantha Cruz-RuizSergio EncarnacionMagdalena HernándezJose Antonio Corona-GomezFania Sheccid-SantiagoJoanna SerwatowskaSinai López-PerdomoCynthia D Flores-AguirreDiego M Arenas-MorenoRobert J OssiboffFausto R Méndez-de la CruzSelene L Fernández-ValverdeMario ZuritaKatarzyna OktabaDiego CortezPublished in: Science (New York, N.Y.) (2024)
Long noncoding RNAs (lncRNAs) are essential regulatory elements of sex chromosomes that act to equalize gene expression levels between males and females. XIST , RSX , and roX2 regulate X chromosomes in placental mammals, marsupials, and Drosophila , respectively. Because the green anole ( Anolis carolinensis ) shows complete dosage compensation of its X chromosome, we tested whether a lncRNA was involved. We found an ancient lncRNA, MAYEX , that gained male-specific expression more than 89 million years ago. MAYEX evolved a notable association with the acetylated histone 4 lysine 16 (H4K16ac) epigenetic mark and the ability to loop its locus to the totality of the X chromosome to increase expression levels. MAYEX is the first lncRNA in reptiles linked to a dosage compensation mechanism that balances the expression of sex chromosomes.