Functional analysis of mesencephalic astrocyte-derived neurotrophic factor in retinal ganglion cells under oxidative...

Glaucoma is optic neuropathy that is characterized by progressive neurodegeneration of the retinal ganglion cells (RGCs) and axons. This condition will lead to visual impairment and bring glaucoma to become the second cause of blindness globally. Neuroprotection in glaucoma is needed to prevent the progression of optic neuropathy. In this study, we examined the effects of the superior colliculus (SC), and mesencephalic astrocyte-derived neurotrophic factor (MANF) secreted from the SC, on RGC survival after oxidative stress. SC slices and RGCs from rats (3-day old) were co-cultured using a 3D-transwell system. In addition, primary RGCs from 4 to 5-day-old rats were cultured and treated with 100 μM hydrogen peroxide (H₂ O₂ ), together with stimulation by MANF. Immunoblot and immunofluorescence analyses indicated down-regulated expression levels of several survival markers of RGCs. Extension of neurites was decreased in RGCs treated with 100 μM H₂ O₂ . Following co-culture with SC slices, or the addition of MANF, we found that both the down-regulated expression of neural markers and extension of neurites caused by oxidative stress in RGCs were blocked. Furthermore, we found a decrease in the expression of neural markers and extension of neurites after co-culture with MANF siRNA-treated SC slices compared with slices treated with mock siRNA, but, RGCs co-cultured with SC slices treated with MANF siRNA displayed no-changed about to apoptosis. These results suggest that MANF secreted from the SC may play an important role in maintenance of function and survival of RGCs. It is also possible that MANF is an important factor in neuroprotection of RGCs. SIGNIFICANCE OF THE STUDY: Glaucoma is a progressive neurodegenerative disease of the retinal ganglion cell (RGC) and their axons. Neuroprotection is aimed at protecting those neurons that are damaged glaucomatous optic neuropathy. We have now examined the effects of superior colliculus, or msencephalic astrocyte-derived neutrophic factor (MANF), secreted from superior colliculus, on RGC survival using co-culture system. Our results suggested that MANF may important key factor in neuroprotection of RGC.