Itgb3 expression is developmentally regulated in pyramidal neurons of mouse cortex and hippocampus

Variants in integrin β3 (Itgb3) are associated with autism spectrum disorder and intellectual disability. Itgb3 deletion in mice leads to aberrant development of excitatory pyramidal neurons in the cerebral cortex and hippocampus, as well as aberrant social and repetitive behaviors. However, its expression pattern in the developing brain has not been well studied. Due to its functional importance in the developing forebrain, we hypothesized that Itgb3 expression would be developmentally regulated and localized to cortical and hippocampal pyramidal neurons in the mouse brain. We found that Itgb3 mRNA is strongly expressed throughout the forebrain, especially in layer 5 of cerebral cortex and CA3 of hippocampus. In mouse cortical layer 5 and in hippocampal CA3, Itgb3 mRNA expression is high at postnatal day 6-7 and is downregulated in cortex by postnatal day 20-21. It is expressed preferentially in glutamatergic excitatory pyramidal neurons. Peak Itgb3 expression therefore coincides with the timeframe for peak dendritic formation and synaptogenesis in cortical and hippocampal glutamatergic excitatory pyramidal neurons.