RT Journal Article
SR Electronic
T1 c-Jun N-terminal Phosphorylation: Biomarker for Cellular Stress rather than Cell Death in the Injured Cochlea
JF eneuro
JO eneuro
FD Society for Neuroscience
SP ENEURO.0047-16.2016
DO 10.1523/ENEURO.0047-16.2016
A1 Anttonen, Tommi
A1 Herranen, Anni
A1 Virkkala, Jussi
A1 Kirjavainen, Anna
A1 Elomaa, Pinja
A1 Laos, Maarja
A1 Liang, Xingqun
A1 Ylikoski, Jukka
A1 Behrens, Axel
A1 Pirvola, Ulla
YR 2016
UL http://www.eneuro.org/content/early/2016/04/24/ENEURO.0047-16.2016.abstract
AB Prevention of auditory hair cell death offers therapeutic potential to rescue hearing. Pharmacological blockade of JNK/c-Jun signaling attenuates injury-induced hair cell loss, but with unsolved mechanisms. We have characterized the c-Jun stress response in the mouse cochlea challenged with acoustic overstimulation and ototoxins, by studying the dynamics of c-Jun N-terminal phosphorylation. It occurred acutely in glial-like supporting cells, inner hair cells and in the cells of the cochlear ion trafficking route, and was rapidly downregulated after exposures. Notably, death-prone outer hair cells lacked c-Jun phosphorylation. As phosphorylation was triggered also by non-traumatic noise levels and as none of the cells showing this activation were lost, c-Jun phosphorylation is a biomarker for cochlear stress rather than an indicator of a death-prone fate of hair cells. Preconditioning with a mild noise exposure before a stronger traumatizing noise exposure attenuated the cochlear c-Jun stress response, suggesting that the known protective effect of sound preconditioning on hearing is linked to suppression of c-Jun activation. Finally, mice with mutations in the c-Jun N-terminal phosphoacceptor sites showed partial, but significant hair cell protection. These data identify the c-Jun stress response as a paracrine mechanism that mediates outer hair cell death.Significance Statement: The current study reveals a detailed time course and cellular pattern of the c-Jun stress response in the cochlea following traumas. It identifies N-terminal phosphorylation of c-Jun as a biomarker for acute cellular stress. Obtained results suggest a novel function for c-Jun phosphorylation in the adult cochlea, not as an intrinsic mediator of cell death, but as a part of a paracrine response that regulates hair cell death following traumas. These results are important for the development of protective therapies against hair cell loss.