X-linked histone demethylase Kdm6a mediates increased axogenesis and Ngn3 expression in XX hypothalamic neurons

AREVALO, M.A.; GARCIA-SEGURA, L.M.; CABRERA ZAPATA, L.E.; CAMBIASSO, M.J.

Glasgow

Congreso; FENS Forum 2020; 2020

FENS

Kdm6a is an X-linked gene that escapes X-inactivation and encodes for a histone demethylase with gene regulation functions. Previous results showed that XX hypothalamic neurons grow at a faster rate, have longer axons, and exhibit higher expression of the neuritogenic gen neurogenin 3 (Ngn3) than XY before brain masculinization. Here we explored the role of Kdm6a in the generation of these XX-mediated sex differences. Using the Four Core Genotypes mouse model, we evaluated Kdm6a mRNA in primary hypothalamic neurons cultures from E15 embryos segregated by sex and genotype. Kdm6a levels were higher in XX than in XY neurons and treatment with 17β-estradiol (10-10 M) did not affect expression. Then, we evaluated the effect of Kdm6a/b activity inhibitor GSK-J4 on the sexually dimorphic expression of Ngn3: GSK-J4 diminished Ngn3 only in XX neurons. Furthermore, we analyzed Kdm6a/b inhibition in wildtype mice cultures segregated by sex and measured the expression of Ngn3, other neuritogenic factors, and genes of the Notch signaling pathway (which negatively control Ngn3). As expected, demethylase inhibition decreased Ngn3 only in female neurons. Otherwise, treatment diminished expression of Neurod1, Neurod2, and Cdk5r1 in both sexes, whereas did not affect Notch signaling elements Hes1, Hes5, and Dll1. Finally, we used siRNAs to knockdown Kdm6a and evaluated neuronal differentiation. Kdm6a silencing reduced axonal elongation only in female neurons, abolishing the sex differences in axogenesis. Altogether, these results point to Kdm6a as a key mediator of the higher axogenesis and Ngn3 expression observed in XX neurons previously to gonadal hormones exposition.Financial support: ANPCyT (PICT 2015 Nº 1333), and SECyT-UNC (2018-2021), Argentina; BFU2017-82754-R and MHE-200057, Spain.