Abolition of the sex difference in Ngn3 by estradiol is depending on sex chromosome complement

A growing body of evidences indicates that some sexually dimorphic traits cannot be solely explained as a result of gonadal steroid action during the critical period of brain masculinization (E18-PN10). Neurogenin 3 (Ngn3), a gene located in mouse chromosome 10 (MGI:893591), is involved in neuritogenesis and morphological differentiation of hippocampal neurons (Salama-Cohen et al., 2006). Recent works from our laboratory have shown the existence of sex difference in the neuritogenic transcription factor Ngn3 in hypothalamic neurons before brain masculization. Moreover 17β-estradiol (E2) abolishes this sex difference (Scerbo et al., 2014). The sex difference in Ngn3 in hypothalamic neurons is depending on sex chromosome complement (Scerbo et al., 2014). In order to study if cell-autonomous actions of sex chromosomes are involved in the effect of E2 on Ngn3, we evaluated Ngn3 mRNA in neuronal cultures.http://www.saneurociencias.org.ar/congreso-2014/Fil: Tomé, Karina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Cisternas, Carla Daniela. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra Introducción a la Química y Física Biológicas A; Argentina.Fil: Cisternas, Carla Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina.Fil: Scerbo Jaureguiberry, Maria Julia. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; Argentina.Fil: Scerbo Jaureguiberry, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina.Fil: Cambiasso, María Julia. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Biología Celular B; Argentina.Fil: Cambiasso, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina.Bioquímica y Biología Molecular (ídem 3.1.10

Estradiol-dependent axogenesis and Ngn3 expression are determined by XY sex chromosome complement in hypothalamic neurons

Hypothalamic neurons show sex differences in neuritogenesis, female neurons have longer axons and higher levels of the neuritogenic factor neurogenin 3 (Ngn3) than male neurons in vitro. Moreover, the effect of 17-β-estradiol (E2) on axonal growth and Ngn3 expression is only found in male-derived neurons. To investigate whether sex chromosomes regulate these early sex differences in neuritogenesis by regulating the E2 effect on Ngn3, we evaluated the growth and differentiation of hypothalamic neurons derived from the “four core genotypes” mouse model, in which the factors of “gonadal sex” and “sex chromosome complement” are dissociated. We showed that sex differences in neurite outgrowth are determined by sex chromosome complement (XX > XY). Moreover, E2 increased the mRNA expression of Ngn3 and axonal length only in XY neurons. ERα/β expressions are regulated by sex chromosome complement; however, E2-effect on Ngn3 expression in XY neurons was only fully reproduced by PPT, a specific ligand of ERα, and prevented by MPP, a specific antagonist of ERα. Together our data indicate that sex chromosomes regulate early development of hypothalamic neurons by orchestrating not only sex differences in neuritogenesis, but also regulating the effect of E2 on Ngn3 expression through activation of ERα in hypothalamic neurons.Fil: Cisternas, Carla Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Cabrera Zapata, Lucas Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Mir, Franco Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Scerbo, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Arevalo, María Angeles. Instituto de Salud Carlos Iii (isciii); EspañaFil: García-Segura, Luis Miguel. Instituto de Salud Carlos Iii (isciii); EspañaFil: Cambiasso, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentin

Neurogenin 3 mediates sex chromosome effects on the generation of sex differences in hypothalamic neuronal development

The organizational action of testosterone during critical periods of development is the cause of numerous sex differences in the brain. However, sex differences in neuritogenesis have been detected in primary neuronal hypothalamic cultures prepared before the peak of testosterone production by fetal testis. In the present study we assessed the hypothesis of that cell-autonomous action of sex chromosomes can differentially regulate the expression of the neuritogenic gene neurogenin 3 (Ngn3) in male and female hypothalamic neurons, generating sex differences in neuronal development. Neuronal cultures were prepared from male and female E14 mouse hypothalami, before the fetal peak of testosterone. Female neurons showed enhanced neuritogenesis and higher expression of Ngn3 than male neurons. The silencing of Ngn3 abolished sex differences in neuritogenesis, decreasing the differentiation of female neurons. The sex difference in Ngn3 expression was determined by sex chromosomes, as demonstrated using the four core genotypes mouse model, in which a spontaneous deletion of the testis-determining gene Sry from the Y chromosome was combined with the insertion of the Sry gene onto an autosome. In addition, the expression of Ngn3, which is also known to mediate the neuritogenic actions of estradiol, was increased in the cultures treated with the hormone, but only in those from male embryos. Furthermore, the hormone reversed the sex differences in neuritogenesis promoting the differentiation of male neurons. These findings indicate that Ngn3 mediates both cell-autonomous actions of sex chromosomes and hormonal effects on neuritogenesis.Peer reviewedPeer Reviewe

Molecular mechanisms involved in the regulation of neuritogenesis by estradiol: Recent advances

This review analyzes the signaling mechanisms activated by estradiol to regulate neuritogenesis in several neuronal populations. Estradiol regulates axogenesis by the activation of the mitogen activated protein kinase (MAPK) cascade through estrogen receptor α located in the plasma membrane. In addition, estradiol regulates MAPK signaling via the activation of protein kinase C and by increasing the expression of brain derived neurotrophic factor and tyrosine kinase receptor B. Estradiol also interacts with the signaling of insulin-like growth factor-I receptor through estrogen receptor α, modulating the phosphoinositide-3 kinase signaling pathway, which contributes to the stabilization of microtubules. Finally, estradiol modulates dendritogenesis by the inhibition of Notch signaling, by a mechanism that, at least in hippocampal neurons, is mediated by G-protein coupled receptor 30. This article is part of a Special Issue entitled 'Neurosteroids'. © 2011 Elsevier Ltd. All rights reserved.Peer Reviewe

Interaction of sex chromosome complement, gonadal hormones and neuronal steroid synthesis on the sexual differentiation of mammalian neurons

Female mouse hippocampal and hypothalamic neurons growing in vitro show a faster development of neurites than male mouse neurons. This sex difference in neuritogenesis is determined by higher expression levels of the neuritogenic factor neurogenin 3 in female neurons. Experiments with the four core genotype mouse model, in which XX and XY animals with male gonads and XX and XY animals with female gonads are generated, indicate that higher levels of neurogenin 3 in developing neurons are determined by the presence of the XX chromosome complement. Female XX neurons express higher levels of estrogen receptors than male XY neurons. In female XX neurons, neuronal derived estradiol increases neurogenin 3 expression and neuritogenesis. In contrast, neuronal-derived estradiol is not able to upregulate neurogenin 3 in male XY neurons, resulting in decreased neuritogenesis compared to female neurons. However, exogenous testosterone increases neurogenin 3 expression and neuritogenesis in male XY neurons. These findings suggest that sex differences in neuronal development are determined by the interaction of sex chromosomes, neuronal derived estradiol and gonadal hormones.This work was supported by Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT), Argentina [grant number PICT 2015 No. 1333]; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina (PIP 2013–2015); Secretaría de Investigación, Ciencia y Tecnología, Universidad de Córdoba (SECyT-UNC), Argentina (2016–2017); Programa CSIC de Cooperación Científica para el Desarrollo I-COOP +2013 [grant number COOPA20038]; Ministerio de Economia, Industria y Competitividad, Spain [grant number BFU2014-51836-C2-1-R]; Centro de Investigación Biomédica en Red de Fragilidad y Envejecimiento Saludable [CIBERFES; CB16/10/00383], Instituto de Salud Carlos III, Madrid, Spain and Fondos FEDER