Loss of Mgat5a-mediated N -glycosylation stimulates regeneration in zebrafish.

BACKGROUND: We are using genetics to identify genes specifically involved in hearing regeneration. In a large-scale genetic screening, we identified mgat5a , a gene in the N -glycosylation biosynthesis pathway whose activity negatively impacts hair cell regeneration.

METHODS: We used a combination of mutant analysis in zebrafish and a hair cell regeneration assay to phenotype the loss of Mgat5a activity in zebrafish. We used pharmacological inhibition of N -glycosylation by swansonine. We also used over-expression analysis by mRNA injections to demonstrate how changes in N -glycosylation can alter cell signaling.

RESULTS: We found that mgat5a was expressed in multiple tissues during zebrafish embryo development, particularly enriched in neural tissues including the brain, retina, and lateral line neuromasts. An mgat5a insertional mutation and a CRISPR/Cas9-generated truncation mutation both caused an enhancement of hair cell regeneration which could be phenocopied by pharmacological inhibition with swansonine. In addition to hair cell regeneration, inhibition of the N -glycosylation pathway also enhanced the regeneration of lateral line axon and caudal fins. Further analysis showed that N -glycosylation altered the responsiveness of TGF-beta signaling.

CONCLUSIONS: The findings from this study provide experimental evidence for the involvement of N -glycosylation in tissue regeneration and cell signaling.