ABSTRACT: 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.
