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PLOS Genet 2019 Dec 26; 15(12):e1008554





The mammalian Pcdhg gene cluster encodes a family of 22 cell adhesion molecules, the gamma-Protocadherins (γ-Pcdhs), critical for neuronal survival and neural circuit formation. The extent to which isoform diversity-a γ-Pcdh hallmark-is required for their functions remains unclear. We used a CRISPR/Cas9 approach to reduce isoform diversity, targeting each Pcdhg variable exon with pooled sgRNAs to generate an allelic series of 26 mouse lines with 1 to 21 isoforms disrupted via discrete indels at guide sites and/or larger deletions/rearrangements. Analysis of 5 mutant lines indicates that postnatal viability and neuronal survival do not require isoform diversity. Surprisingly, given reports that it might not independently engage in trans-interactions, we find that γC4, encoded by Pcdhgc4, is the only critical isoform. Because the human orthologue is the only PCDHG gene constrained in humans, our results indicate a conserved γC4 function that likely involves distinct molecular mechanisms.


We would like to thank the scientific services at the Jackson Laboratory for assistance throughout this project, including Genetic Engineering Technologies, Microinjection, and Reproductive Sciences services for the production and preservation of new mutants, the Genome Technologies service for sequencing, and the Bioinformatics service for data analysis. We would also like to thank Kate Miers for assistance with the mouse colony.

Open access under the terms of the Creative Commons Attribution License.