Shielding Retinal Ganglion Cells: Suppression of the PAX6-JNK3 Axis Protects Against NMDA-Induced Excitotoxicity in a Glaucoma Model [ChIP-seq]

Retinal degenerative diseases frequently cause visual impairment due to a lack of regeneration systems and self-renewable cells. Glaucoma is characterized by the progressive degeneration of retinal ganglion cells (RGCs), yet the underlying mechanisms remain poorly understood. Here, our study investigated the role of the transcription factor PAX6 in RGC death during NMDA excitotoxicity, a model for glaucoma. Using public single-cell RNA sequencing data, we found that PAX6 is consistently expressed in RGCs across both mouse and human retinas. Notably, we demonstrated that PAX6 phosphorylation was enhanced following NMDA exposure, and JNK3 was identified as a key kinase responsible for PAX6 phosphorylation. Epigenome-wide analysis revealed co-occupancy of PAX6 and JNK3 at key apoptotic gene promoters, with PAX6 acting as a recruitment factor for JNK3. Furthermore, suppressing PAX6 and JNK3 significantly protected against NMDA-induced RGC death, highlighting PAX6-JNK3 contribution to excitotoxicity-mediated apoptosis. Collectively, our findings elucidate a novel mechanism of RGC death in glaucoma, implicating the PAX6-JNK3 signaling axis as a critical mediator of retinal cell fate under excitotoxic conditions, suggesting potential therapeutic targets for preserving RGCs in glaucoma. Overall design: We administered NMDA (40 mM, 1 µL; n = 4) and phosphate-buffered saline (PBS, used as a control, 1 µL; n = 4) by intravitreal injection into wild-type (WT) mice. ChIP-seq for PAX6 were performed in PBS- or NMDA-injected mouse retinas.