Dual-Specificity Phosphatase 1 (DUSP1) Has a Central Role in Redox Homeostasis and Inflammation in the Mouse Cochlea

Stress-activated protein kinases (SAPK) are associated with sensorineural hearing loss (SNHL) of multiple etiologies. Their activity is tightly regulated by dual-specificity phosphatase 1 (DUSP1), whose loss of function leads to sustained SAPK activation. Dusp1 gene knockout in mice accelerates SNHL progression and triggers inflammation, redox imbalance and hair cell (HC) death. To better understand the link between inflammation and redox imbalance, we analyzed the cochlear transcriptome in Dusp1(−/−) mice. RNA sequencing analysis (GSE176114) indicated that Dusp1(−/−) cochleae can be defined by a distinct profile of key cellular expression programs, including genes of the inflammatory response and glutathione (GSH) metabolism. To dissociate the two components, we treated Dusp1(−/−) mice with N-acetylcysteine, and hearing was followed-up longitudinally by auditory brainstem response recordings. A combination of immunofluorescence, Western blotting, enzymatic activity, GSH levels measurements and RT-qPCR techniques were used. N-acetylcysteine treatment delayed the onset of SNHL and mitigated cochlear damage, with fewer TUNEL(+) HC and lower numbers of spiral ganglion neurons with p-H2AX foci. N-acetylcysteine not only improved the redox balance in Dusp1(−/−) mice but also inhibited cytokine production and reduced macrophage recruitment. Our data point to a critical role for DUSP1 in controlling the cross-talk between oxidative stress and inflammation.