X chromosome inactivation and active X upregulation in therian mammals: facts, questions, and hypotheses.

Reiner A Veitia (1) , Frédéric Veyrunes (2) , Samuel Bottani (3) , James A Birchler (4)

1 IJM (UMR_7592) - Institut Jacques Monod
2 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier
3 MSC - Matière et Systèmes Complexes
4 Division of Bioiogical Sciences, University of Missouri, Columbia

X chromosome inactivation is a mechanism that modulates the expression of X-linked genes in eutherian females (XX). Ohno proposed that to achieve a proper balance between X-linked and autosomal genes, those on the active X should also undergo a 2-fold upregulation. Although some support for Ohno's hypothesis has been provided through the years, recent genomic studies testing this hypothesis have brought contradictory results and fueled debate. Thus far, there are as many results in favor as against Ohno's hypothesis, depending on the nature of the datasets and the various assumptions and thresholds involved in the analyses. However, they have confirmed the importance of dosage balance between X-linked and autosomal genes involved in stoichiometric relationships. These facts as well as questions and hypotheses are discussed below.

Mots clés: X inactivation; X chromosome upregulation; imprinting; monoallelic expression; dosage balance

Domaines: Biochimie, Biologie Moléculaire

Reiner A Veitia, Frédéric Veyrunes, Samuel Bottani, James A Birchler. X chromosome inactivation and active X upregulation in therian mammals: facts, questions, and hypotheses.. Journal of molecular cell biology, 2015, 7 (1), pp.2-11. ⟨10.1093/jmcb/mjv001⟩. ⟨hal-01131346⟩