Asxl3 haploinsufficiency in mice contributes to autism-like phenotypes via thyroid hormone-dependent development of parvalbumin-positive neurons
Autism spectrum disorder (ASD) is a complex neurodevelopmental condition associated with mutations in multiple genes, including ASXL3. However, the underlying mechanisms remain unclear. Here, Asxl3 heterozygous knockout (Asxl3+/-) mice exhibited reduced social novelty preference, repetitive behaviors, increased anxiety, and impaired learning and memory. In the retrosplenial cortex (RSC) and hippocampus of these mice, an increased number of parvalbumin (PV)-positive neurons was observed, accompanied by a decreased neuronal density in cortical layers II, III, and V. RNA sequencing identified 837 dysregulated genes in the brains of Asxl3+/- mice, enriched in neurodevelopmental functions. Among these target genes, Asxl3 haploinsufficiency significantly promotes the overexpression of the thyroid hormone (TH) metabolism-related gene Dio3, leading to reduced TH levels in the Asxl3+/- mice. Knocking down the TH receptor gene Thra in inhibitory neuron precursors in vivo recapitulated the increased number of PV-positive neurons observed in Asxl3+/- mice. Notably, supplementation with TH in neonatal Asxl3+/- mice or upregulation of Asxl3 expression via retro-orbital injection of adeno-associated virus (AAV) ameliorated the developmental abnormalities of PV-positive neurons and ASD-related behavioral phenotypes. Collectively, our findings suggest that ASXL3 mutations may contribute to the pathogenesis of ASD by affecting the development of PV-positive neurons through TH.