Neurodevelopmental deficits and cell-type-specific transcriptomic perturbations in a mouse model of HNRNPU haploinsufficiency

Heterozygous de novo loss-of-function mutations in the gene expression regulator HNRNPU cause an early-onset developmental and epileptic encephalopathy. To gain insight into pathological mechanisms and lay the groundwork for developing targeted therapies, we characterized the neurophysiologic and cell-type-specific transcriptomic consequences of a mouse model of HNRNPU haploinsufficiency. Heterozygous mutants demonstrated neuroanatomical abnormalities, global developmental delay and impaired ultrasonic vocalizations, and increased seizure susceptibility, thus modeling aspects of the human disease. Single−cell RNA-sequencing of hippocampal and neocortical cells revealed widespread, yet modest, dysregulation of gene expression across mutant neuronal subtypes. We observed an increased burden of differentially-expressed genes in mutant excitatory neurons of the subiculum− a region of the hippocampus implicated in temporal lobe epilepsy. Evaluation of transcriptomic signature reversal as a therapeutic strategy highlighted the potential importance of generating cell-type−specific signatures. Overall, this work provides insight into HNRNPU−mediated disease mechanisms, and provides a framework for using single−cell RNA−sequencing to study transcriptional regulators implicated in disease.