Neuroligin-3 Activates Nrf2 Signaling To Protect Human Retinal Cells From Hydrogen Peroxide

Retinal degeneration disease is the the main cause of blindness,including agerelated macular degeneration and diabetic retinopathy.The high incidence,seriously affecting the patient's quality of life,and clinical treatment is different,the effect is often not obvious.Intensified oxidative stress can cause severe damage to human retinal pigment epithelium(RPE)cells and retinal ganglion cells(RGCs),leading to retinal neurodegeneration.Therefore,it is particularly important to study the pathophysiological processes of retinal pigment epithelial cells and retinal ganglion cells for oxidative stress injury.Neuroligin-3(NLGN3)is a cell adhesion protein.NLGN3 locates at neuronal postsynaptic membrane,which is essential for synapse formation.Studies have recently shown that NLGN3 is a novel and key mitogen,which is sufficient and necessary to promote cell survival and growth.However,the potential role of NLGN3 in human retinal cells is not yet clear.In this study,we used retinal pigment epithelial cells and retinal ganglion cells as two main retinal cells.Firstly we observed whether NLGN3 could protect human RPE cells and RGCs induced by hydrogen peroxide(H2O2),and then explored and clarified the mechanism of the protective effects of NLGN3 on retinal cells induced by oxidative damage.We showed that NLGN3 pre-treatment efficiently inhibited hydrogen peroxide(H2O2)-induced death and apoptosis of human RPE cells and RGCs.H2O2-induced ROS accumulation,lipid peroxidation and DNA damage were largely attenuated by NLGN3 as well.It is suggested that NLGN3 had protective effects on H2O2-induced human RPE cells and RGCs.Further study found that NLGN3 activated the nuclearfactor-E2-related factor 2(Nrf2)signal in retinal cells,resulting in the transfer of Nrf2 from the cytoplasm to the nucleus,NLGN3 also increased transcription of its downstream genes at the transcriptional level,causing expression of key anti-oxidant genes(HO1,NQO1 and GCLC)in RPE cells and RGCs,resulting in its anti-oxidant effect.Subsequent experiments revealed that Akt-m TORC1 inhibitors,RAD001 and LY294002,almost reversed NLGN3-induced Nrf2 signaling activation.Significantly,sh RNA-mediated knockdown of Nrf2 almost reversed NLGN3-induced retinal cell protection against H2O2.These results suggest that the protective effect of NLGN3 on H2O2-induced RPE cells and RGCs may be through its activation of Akt-m TORC1 signaling pathway.This study provides an experimental basis for NLGN3 as a potential drug for the prevention and treatment of retinal degenerative diseases.The study is divided into two parts:Part I: The protective effect of NLGN3 on human RPE cells and RGCs induced by H2O2Part II: Study on the protective mechanism of NLGN3 on human RPE cells and RGCs induced by H2O2.