Enhancing WNT-Signaling Restores Cortical Neuronal Spine Maturation and Synaptogenesis in Tbr1 Mutants

Tbr1 is a high confidence autism spectrum disorder (ASD) gene encoding a transcription factor with distinct pre- and postnatal functions. Postnatally, Tbr1 conditional mutants (CKOs) and constitutive heterozygotes have immature dendritic spines and reduced synaptic density. Tbr1 regulates expression of several genes that underlie synaptic defects, including a kinesin (Kif1a) and a WNT signaling ligand (Wnt7b). Furthermore, Tbr1 mutant corticothalamic neurons have reduced thalamic axonal arborization. LiCl and a GSK3b-inhibitor, two WNT-signaling agonists, robustly rescue the dendritic spines, synaptic and axonal defects, suggesting that this could have relevance for therapeutic approaches in some forms of ASD. Examination of TBR1 regulated genes in layer 5 FACS purified neurons from P5 mouse medial prefrontal cortex.