Repressor element 1-silencing transcription factor deficiency yields profound hearing loss through K(v)7.4 channel upsurge in auditory neurons and hair cells

Repressor element 1-silencing transcription factor (REST) is a transcriptional repressor that recognizes neuron-restrictive silencer elements in the mammalian genomes in a tissue- and cell-specific manner. The identity of REST target genes and molecular details of how REST regulates them are emerging. We performed conditional null deletion of Rest (cKO), mainly restricted to murine hair cells (HCs) and auditory neurons (aka spiral ganglion neurons [SGNs]). Null inactivation of full-length REST did not affect the development of normal HCs and SGNs but manifested as progressive hearing loss in adult mice. We found that the inactivation of REST resulted in an increased abundance of K(v)7.4 channels at the transcript, protein, and functional levels. Specifically, we found that SGNs and HCs from Rest cKO mice displayed increased K(v)7.4 expression and augmented K(v)7 currents; SGN’s excitability was also significantly reduced. Administration of a compound with K(v)7.4 channel activator activity, fasudil, recapitulated progressive hearing loss in mice. In contrast, inhibition of the K(v)7 channels by XE991 rescued the auditory phenotype of Rest cKO mice. Previous studies identified some loss-of-function mutations within the K(v)7.4-coding gene, Kcnq4, as a causative factor for progressive hearing loss in mice and humans. Thus, the findings reveal that a critical homeostatic K(v)7.4 channel level is required for proper auditory functions.