Investigation of the influence of sex and prenatal steroids on synapse formation in human cerebral organoids.

几种突出的神经发育障碍在男性和女性中的患病率不同(McCarthy 2016)。例如，自闭症谱系疾病(ASC)中似乎存在男性偏见，估计患有自闭症谱系疾病的男性与女性的比例为3：1(Loome，Hull和Mandy 2017)。尽管有越来越多的证据表明，包括雄激素和雌激素在内的产前类固醇激素与自闭症可能性的增加有关，但这种差异的原因仍不清楚(Baron-Cohen等人)。2020)，睾丸激素水平升高与更高的ASC可能性或特征相关(Baron-Cohen等人。2011年；Bos等人。2016)。产前类固醇在大脑的发育和性别分化中起着关键作用。男性在怀孕18至24周和出生后头几个月的血清睾酮水平会升高，恰逢神经发育的关键阶段(Hines，Constantinescu和Spencer 2015)。胎儿类固醇可能导致啮齿类动物潜在的性别差异，因此最终结果是相同的，但雄性和雌性的发育机制不同(Sellers等人。2020)。用雄激素治疗人类神经干细胞可促进其增殖，并影响约200个基因的表达，包括与ASC相关或参与ASC的基因(Quartier等人。2018年)。Kelava等人。显示类固醇，特别是雄激素，影响人类大脑器官的早期皮质生成(2020)。然而，类固醇如何影响突触发育尚不清楚，而突触发育在ASC中受到影响。与ASC相关的几个高渗透性突变与突触功能的调节有关，包括SHANK3和NRXN1基因突变(Zoghbi和Bear 2012)。新出现的证据表明，类固醇也可以作为神经递质，影响哺乳动物的神经元活动(Rudolph等人。2016)。然而，人们对类固醇在发育中的人类皮质中的作用知之甚少。现在已经有了可再生生长脑器官的既定方案(Lancaster等人。2013年；贝拉斯科等人。2019年)，可用作早期人脑发育的模型(Camp等人)。2015)来研究这样的问题。考虑到类固醇在ASC可能性中的作用，研究产前类固醇对皮质和突触发育的影响是值得的。据报道，ASC相关基因SHANK3和类固醇之间有一种有趣的联系，性激素由此调节小腿的表达(Berkel等人。2018年)。来自斯利瓦斯塔瓦实验室现有的已发表和未发表的数据表明，男性人类诱导多能干细胞衍生(HiPSC)前脑神经元可以对一系列胎儿类固醇(例如17B-雌二醇)做出反应，从而影响轴突生长、突触蛋白表达和突触基因表达，例如与NRXN1相互作用的突触蛋白(Shum等人)。2015年)。带有SHANK3和NRXN1突变的雄性和雌性HiPSC系的实验室数据表明，在神经元网络活动(SHANK3系)或基因表达差异(NRXN1系)方面，男性和女性之间存在潜在差异。

Several prominent neurodevelopmental disorders have differing prevalence between males and females (McCarthy 2016). For example, there appears to be a male bias in autism spectrum condition (ASC), with an estimated 3:1 ratio of males to females with ASC (Loomes, Hull, and Mandy 2017). It is still unclear why this difference exists, although there is increasing evidence that prenatal steroids including androgens and estrogens are associated with increased likelihood of autism (Baron-Cohen et al. 2020), with increased testosterone levels associated with higher ASC likelihood or traits (Baron-Cohen et al. 2011; Bos et al. 2016). Prenatal steroids have key roles in the development and sexual differentiation of the brain. Levels of testosterone in serum are elevated in males between 18 and 24 weeks of gestation and in the first months after birth, coinciding with key stages of neurodevelopment (Hines, Constantinescu, and Spencer 2015). Fetal steroids may contribute to latent sex differences in rodents, such that the end result is the same but the developmental mechanisms differ in males and females (Sellers et al. 2020). Human neural stem cell treatment with androgens increases their proliferation and affects expression of ~200 genes, including genes associated with or involved in ASC (Quartier et al. 2018). Kelava et al. show that steroids, specifically androgens, affect early corticogenesis in human cerebral organoids (2020). However, it is not known how steroids affect synapse development, which is affected in ASC. Several highly penetrant mutations associated with ASC have been linked to the regulation of synaptic function, including mutations in the SHANK3 and NEUREXIN (NRXN1) genes (Zoghbi and Bear 2012). Emerging evidence shows steroids can also act as neurotransmitters and influence neuronal activity in mammals (Rudolph et al. 2016). However, little is known about steroid action in the developing human cortex. There are now established protocols for reproducibly growing cerebral organoids (Lancaster et al. 2013; Velasco et al. 2019), which can be used as a model of early human brain development (Camp et al. 2015) to study such questions. Given also the proposed role of steroids in ASC likelihood, an investigation of the effect of prenatal steroids on cortical and synapse development is worthwhile. An intriguing link between the ASC-linked gene SHANK3 and steroids has been reported, whereby sex hormones regulate SHANK expression (Berkel et al. 2018). Existing published and unpublished data from the Srivastava lab suggests that male human induced pluripotent stem cell-derived (hiPSC) forebrain neurons can respond to a range of fetal steroids, for example 17B-estradiol, with effects on neurite outgrowth, synaptic protein expression, and synaptic gene expression, such as synaptic proteins interacting with NRXN1 (Shum et al. 2015). Lab data from male and female hiPSC lines with mutations in SHANK3 and NRXN1 indicates potential male-female differences in neuronal network activity (SHANK3 hiPSC lines) or gene expression differences (NRXN1 hiPSC lines).