Loss of Zmiz1 in Mice Leads to Impaired Cortical Development and Autistic-Like Behaviors

De novo mutations in transcriptional regulators are emerging as key risk factors contributing to the etiology of neurodevelopmental disorders. Human genetic studies have recently identified ZMIZ1 and its de novo mutations as a cause of a neurodevelopmental syndrome strongly associated with intellectual disability, autism, attention-deficit/hyperactivity disorder, microcephaly, and other developmental anomalies. However, the role of ZMIZ1 in brain development or how ZMIZ1 mutations cause neurological phenotypes is unknown.

We generated forebrain-specific Zmiz1 mutant mice (Zmiz1-knockout) to assess ZMIZ1 function in cortical development. Neural progenitors, excitatory neurons, and glia were assessed using immunolabeling. Neuron-specific reconstruction was applied to callosal projection neurons to analyze dendritic arborization and projection through the corpus callosum. Behavioral tests assessed motor activity, anxiety, communication, and social interactions. RNA sequencing at multiple developmental stages and chromatin immunoprecipitation sequencing (ChIP-seq) revealed molecular pathways and targets regulated by ZMIZ1.

Loss of ZMIZ1 led to cortical microcephaly, corpus callosum dysgenesis, and abnormal differentiation of upper-layer cortical neurons. Zmiz1-knockout mice showed alterations in motor activity, anxiety, communication, and social interactions with strong sex differences, resembling phenotypes associated with autism. Zmiz1 mutation led to transcriptomic changes disrupting neurogenesis, neuron differentiation programs, and synaptic signaling. We identified Zmiz1-mediated downstream regulation of key neurodevelopmental genes, including Lhx2, Auts2, and EfnB2. Importantly, reactivation of the ephrin-B2 pathway rescued the dendritic outgrowth deficits in Zmiz1 mutant cortical neurons.

Our in vivo findings provide insight into Zmiz1 function in cortical development and reveal mechanistic underpinnings of ZMIZ1 syndrome, thereby providing valuable information for future studies on this neurodevelopmental disorder.