Epilepsy Associated Gene, Pcdh7, Is Dispensable for Brain Development in Mice.

Background/

Objectives

Protocadherin 7 (Pcdh7) belongs to the protocadherin family, the largest subgroup of cell adhesion molecules. Members of this family are highly expressed in the brain, where they serve fundamental roles in many neurodevelopmental processes, including axon guidance, dendrite self-avoidance, and synaptic formation. PCDH7 has been strongly associated with epilepsy in multiple genome-wide association studies (GWAS), as well as with schizophrenia, PTSD, and childhood aggression. Despite these associations, the specific contributions of PCDH7 to epileptogenesis and brain development remain largely unexplored. Most of the existing literature on PCDH7 focuses on its function during cancer progression, with only one study suggesting that PCDH7 regulates dendritic spine morphology and synaptic function via interaction with GluN1.

Methods

Here, we generate, validate, and characterize a murine null Pcdh7 allele in which a large deletion was introduced by CRISPR.

Results

Analysis of embryonic, postnatal, and adult brain datasets confirmed PCDH7 widespread expression. Pcdh7+/- and Pcdh7-/- mice present no gross morphological defects and normal cortical layer formation. However, a seizure susceptibility assay revealed increased latencies in Pcdh7+/- mice, but not in Pcdh7+/+ and Pcdh7-/- mice, potentially explaining the association of PCDH7 with epilepsy.

Conclusions

This initial characterization of Pcdh7 null mice suggests that, despite its widespread expression in the CNS and involvement in human epilepsy, PCDH7 is not essential for murine brain development and thus is not a suitable animal model for understanding PCDH7 disruption in humans. However, further detailed analysis of this mouse model may reveal circuit or synaptic abnormalities in Pcdh7 null brains.