<i>MAYEX</i>is an old long noncoding RNA recruited for X chromosome dosage compensation in a reptile
Mariela Tenorio, Samantha Cruz-Ruiz, Sergio Encarnación‐Guevara, Magdalena Hernández, José Antonio Corona-Gómez, Fania Sheccid-Santiago, Joanna Serwatowska, Sinai López-Perdomo, Cynthia D. Flores-Aguirre, Diego M. Arenas‐Moreno, Robert J. Ossiboff, Fausto R. Méndez‐de la Cruz, Selene L. Fernández-Valverde, Mario Zurita, Katarzyna Oktaba, Diego Cortez
Abstract
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.