Whole brain transcriptomic analysis of Tbr1-K228E mutant mice

Mutations of Tbr1, a high-confidence ASD (autism spectrum disorder)-risk gene encoding the transcription regulator TBR1, in mice have been shown to induce diverse ASD-related molecular, synaptic, neuronal, and behavioral dysfunctions. However, it remains unclear whether Tbr1 mutations derived from autistic individuals cause similar dysfunctions in mice remains unclear. Here we generated and characterized mice carrying the TBR1-K228E de novo mutation identified in human ASD and identified various ASD-related phenotypes. In heterozygous mice carrying this mutation (Tbr1+/K228E mice), the levels of the TBR1-K228E protein, which cannot bind to target DNA, were strongly increased. RNA-Seq analysis of the Tbr1+/K228E embryonic brain indicated significant changes in the expression of genes associated with neurons, astrocytes, ribosomes, neuronal synapses, and ASD risk. The Tbr1+/K228E neocortex displayed abnormal distribution of parvalbumin-positive interneurons, with the density lower in superficial layers but higher in deep layers. This was associated with increased inhibitory synaptic transmission in layer 6 pyramidal neurons, which was resistant to compensation by network activity. Behaviorally, Tbr1+/K228E mice showed decreased social interaction, increased self-grooming, and modestly increased anxiety-like behaviors. These results suggest that the human heterozygous TBR1-K228E mutation induces ASD-related protein, transcriptomic, neuronal, synaptic, and behavioral dysfunctions in mice. Whole brain transcriptome of E16.5 wild-type and Tbr1-K228E mutant mice.

编码转录调节因子TBR1的高置信度自闭症谱系障碍（autism spectrum disorder, ASD）易感基因Tbr1，其在小鼠中的突变已被证实可引发多种与ASD相关的分子、突触、神经元及行为功能异常。然而，源自自闭症患者的Tbr1突变是否会在小鼠体内引发相似的功能异常，目前仍不明确。本研究构建并鉴定了携带人类ASD患者中发现的TBR1-K228E新生突变的小鼠，并识别出多种与ASD相关的表型。在携带该突变的杂合子小鼠（Tbr1+/K228E小鼠）体内，无法结合靶DNA的TBR1-K228E蛋白水平显著升高。对Tbr1+/K228E小鼠胚胎脑组织进行RNA测序（RNA-Seq）分析显示，与神经元、星形胶质细胞、核糖体、神经元突触及ASD易感相关的基因表达发生了显著变化。Tbr1+/K228E小鼠的新皮层中，小白蛋白阳性中间神经元的分布异常：浅层密度降低，而深层密度升高。这与第6层锥体神经元的抑制性突触传递增强相关，且该增强无法通过网络活动进行代偿。行为学检测显示，Tbr1+/K228E小鼠表现出社交互动减少、自主梳理行为增多，以及轻度增加的焦虑样行为。上述结果表明，人类杂合子TBR1-K228E突变可在小鼠体内引发与ASD相关的蛋白、转录组、神经元、突触及行为功能异常。本数据集包含胚胎发育第16.5天（E16.5）野生型与Tbr1-K228E突变型小鼠的全脑转录组数据。