Mature retinal ganglion cells (RGCs), like other CNS neurons, cannot regrow injured axons into a myelin-rich environment. If stimulated by macrophage-derived factors, however, RGCs can regenerate their axons for considerable distances through the distal optic nerve. Using this "sensitized background," we investigated the effects of either increasing the expression or suppressing the activity of the Nogo receptor (NgR). NgR mediates the growth-inhibiting effects of three myelin proteins, Nogo, OMgp (oligodendrocyte-myelin glycoprotein), and MAG (myelin-associated glycoprotein). Transfecting growth-sensitized RGCs with adeno-associated viruses expressing a dominant-negative form of NgR (NgR DN ) increased axon regeneration several-fold; however, when the growth program of RGCs was not activated, NgR DN expression had no beneficial effects. Overexpression of wild-type NgR blocked almost all regeneration from growthsensitized RGCs and caused axons proximal to the lesion site to retract. We conclude that gene therapy is an effective approach to enhancing axon regeneration in the CNS and that inactivation of NgR functioning greatly enhances axon regeneration provided the intrinsic growth program of neurons is activated.

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Across neurodegenerative diseases, common mechanisms may reveal novel therapeutic targets based on neuronal protection, repair, or regeneration, independent of etiology or site of disease pathology. To address these mechanisms and discuss emerging treatments, in April, 2021, Glaucoma Research Foundation, BrightFocus Foundation, and the Melza M. and Frank Theodore Barr Foundation collaborated to bring together key opinion leaders and experts in the field of neurodegenerative disease for a virtual meeting titled “Solving Neurodegeneration”. This “think-tank” style meeting focused on uncovering common mechanistic roots of neurodegenerative disease and promising targets for new treatments, catalyzed by the goal of finding new treatments for glaucoma, the world’s leading cause of irreversible blindness and the common interest of the three hosting foundations. Glaucoma, which causes vision loss through degeneration of the optic nerve, likely shares early cellular and molecular events with other neurodegenerative diseases of the central nervous system. Here we discuss major areas of mechanistic overlap between neurodegenerative diseases of the central nervous system: neuroinflammation, bioenergetics and metabolism, genetic contributions, and neurovascular interactions. We summarize important discussion points with emphasis on the research areas that are most innovative and promising in the treatment of neurodegeneration yet require further development. The research that is highlighted provides unique opportunities for collaboration that will lead to efforts in preventing neurodegeneration and ultimately vision loss.