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Updated: Jun 12, 2025

A Non-random Mouse Model for Pharmacological Reactivation of Mecp2 on the Inactive X Chromosome
Published on: May 22, 2019
MAYEX is an old long noncoding RNA recruited for X chromosome dosage compensation in a reptile
Mariela Tenorio1, Samantha Cruz-Ruiz2, Sergio Encarnación-Guevara1
1Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), CP62210 Cuernavaca, México.
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.
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