Deciphering the genetic interactions between Pou4f3, Gfi1, and Rbm24 in maintaining cochlear hair cell survival

Mammals harbor a limited number of sound-receptor hair cells (HCs) that cannot be regenerated after damage. Thus, investigating the underlying molecular mechanisms that maintain HC survival is crucial for preventing hearing impairment. Intriguingly,Pou4f3^-/-orGfi1^-/-HCs form initially but then rapidly degenerate, whereasRbm24^-/-HCs degenerate considerably later. However, the transcriptional cascades involving Pou4f3, Gfi1, and Rbm24 remains undescribed. Here, we demonstrate thatRbm24expression is completely repressed inPou4f3^-/-HCs but unaltered inGfi1^-/-HCs, and further that the expression of both POU4F3 and GFI1 is intact inRbm24^-/-HCs. Moreover, by usingin vivomouse transgenic reporter assays, we identify threeRbm24enhancers to which POU4F3 binds. Lastly, throughin vivogenetic testing of whether Rbm24 restoration alleviates the degeneration ofPou4f3^-/-HCs, we show that ectopic Rbm24 alone cannot preventPou4f3^-/-HCs from degenerating. Collectively, our findings provide new molecular and genetic insights into how HC survival is regulated.