Celf4 controls mRNA translation underlying synaptic development in the prenatal mammalian neocortex

Abnormalities in neocortical and synaptic development are linked to neurodevelopmental disorders. However, the molecular and cellular mechanisms governing initial synapse formation in the prenatal neocortex remain poorly understood. Using polysome profiling coupled with snRNAseq on human cortical samples at various fetal phases, we identify human mRNAs, including those encoding synaptic proteins, with finely controlled translation in distinct cell populations of developing frontal neocortices. Examination of murine and human neocortex reveals that the RNA binding protein and translational regulator, CELF4, is expressed in compartments enriched in initial synaptogenesis: the marginal zone and the subplate. We also find that Celf4/CELF4-target mRNAs are encoded by risk genes for adverse neurodevelopmental outcomes translating into synaptic proteins. Surprisingly, deleting Celf4 in the forebrain disrupts the balance of subplate synapses in a sex-specific fashion. This highlights the significance of RNA binding proteins and mRNA translation in evolutionarily advanced synaptic development, potentially contributing to sex differences. While progress in early human cortical development is acknowledged, a limited understanding persists regarding transcriptomic and translational profiles in subplate neurons. Here, the authors discovered an enrichment of autism spectrum disorder risk genes in subplate neurons, underscoring the crucial role played by the RNA-binding protein CELF4 in translating synaptic mRNAs during neocortical development.

Automated summary

This study reveals the critical role of RNA-binding protein CELF4 in prenatal neocortical development, specifically in the translation of synaptic mRNA and the development of subplate synapses. The study also highlights the enrichment of autism spectrum disorder risk genes in subplate neurons.