Pottmeier Philipp, Nikolantonaki Danai, Lanner Fredrik, Peuckert Christiane, Jazin Elena
Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institute and Karolinska University Hospital, Stockholm, Sweden.
Front Cell Dev Biol. 2024 May 1;12:1341373. doi: 10.3389/fcell.2024.1341373. eCollection 2024.
Sex differences in the developing human brain are primarily attributed to hormonal influence. Recently however, genetic differences and their impact on the developing nervous system have attracted increased attention. To understand genetically driven sexual dimorphisms in neurodevelopment, we investigated genome-wide gene expression in an differentiation model of male and female human embryonic stem cell lines (hESC), independent of the effects of human sex hormones. Four male and four female-derived hESC lines were differentiated into a population of mixed neurons over 37 days. Differential gene expression and gene set enrichment analyses were conducted on bulk RNA sequencing data. While similar differentiation tendencies in all cell lines demonstrated the robustness and reproducibility of our differentiation protocol, we found sex-biased gene expression already in undifferentiated ESCs at day 0, but most profoundly after 37 days of differentiation. Male and female cell lines exhibited sex-biased expression of genes involved in neurodevelopment, suggesting that sex influences the differentiation trajectory. Interestingly, the highest contribution to sex differences was found to arise from the male transcriptome, involving both Y chromosome and autosomal genes. We propose 13 sex-biased candidate genes (10 upregulated in male cell lines and 3 in female lines) that are likely to affect neuronal development. Additionally, we confirmed gene dosage compensation of X/Y homologs escaping X chromosome inactivation through their Y homologs and identified a significant overexpression of the Y-linked demethylase and in male hESC during neuron development, confirming previous results in neural stem cells. Our results suggest that genetic sex differences affect neuronal differentiation trajectories, which could ultimately contribute to sex biases during human brain development.
发育中的人类大脑的性别差异主要归因于激素影响。然而，最近基因差异及其对发育中的神经系统的影响引起了越来越多的关注。为了了解神经发育中由基因驱动的性二态性，我们在男性和女性人类胚胎干细胞系（hESC）的分化模型中研究了全基因组基因表达，该模型不受人类性激素影响。四个男性来源和四个女性来源的hESC系在37天内分化为混合神经元群体。对大量RNA测序数据进行了差异基因表达和基因集富集分析。虽然所有细胞系中相似的分化趋势证明了我们分化方案的稳健性和可重复性，但我们发现即使在第0天未分化的ESC中就已经存在性别偏向的基因表达，但在分化37天后最为明显。雄性和雌性细胞系表现出参与神经发育的基因的性别偏向表达，这表明性别会影响分化轨迹。有趣的是，发现对性别差异贡献最大的是雄性转录组，涉及Y染色体和常染色体基因。我们提出了13个性别偏向的候选基因（10个在雄性细胞系中上调，3个在雌性细胞系中上调），它们可能会影响神经元发育。此外，我们通过Y同源物证实了逃避X染色体失活的X/Y同源物的基因剂量补偿，并在神经元发育过程中鉴定出雄性hESC中Y连锁去甲基化酶的显著过表达，证实了先前在神经干细胞中的结果。我们的结果表明，遗传性别差异会影响神经元分化轨迹，这最终可能导致人类大脑发育过程中的性别偏向。
