A "Tric" to tighten cell-cell junctions in the cochlea for hearing.

Tricellulin is a tricellular tight junction-associated membrane protein that controls movement of solutes at these specialized cell intersections. Mutations in the gene encoding tricellulin, TRIC, lead to nonsyndromic deafness. In this issue of the JCI, Nayak et al. created a gene-targeted knockin mouse in order to mimic the pathology of a human TRIC mutation. Deafness appears to be caused either by an increase in the K+ ion concentration around the basolateral surfaces of the outer hair cells or, alternatively, by an increase in small molecules such as ATP around the hair bundle, leading to cellular dysfunction and degeneration. Furthermore, the mice have features suggestive of syndromic hearing loss, which may have implications for care and treatment of patients harboring TRIC mutations.