Sfswap, a poorly characterized splicing factor, is involved in multiple biological processes. It plays a role in regulating pre-mRNA splicing, especially as a negative regulator of global pre-mRNA splicing and a positive regulator of intron retention. It is also associated with the O-GlcNAcylation pathway, where it regulates OGT intron detention. Additionally, it is implicated in the development of the inner ear [1,2,3].

In mouse models, homozygous Sfswap mutants display vestibular and cochlear defects consistent with disrupted Notch signaling. These mutants show hyperactivity, circling behavior, and significantly impaired hearing. The cochlea of newborn Sfswap mutant mice has a reduction in outer hair cells and supporting cells, along with ectopic inner hair cells. The phenotype is similar to that of hypomorphic alleles of the Notch ligand Jagged1 (Jag1), and Jag1;Sfswap compound mutants have more severe inner ear defects, indicating a genetic interaction between Sfswap and Jag1. Also, expression of genes involved in Notch signaling in the inner ear is reduced in Sfswap mutants [2].

In conclusion, Sfswap is an important regulator of pre-mRNA splicing and has a significant impact on inner ear development. The study of Sfswap knockout mouse models has revealed its role in disrupting Notch signaling in the inner ear, contributing to our understanding of inner ear-related diseases.