Injury to axons of the central nervous system, whether in the form of a physical injury or neurodegenerative diseases, remains a significant burden in modern medicine. Whereas axons of the peripheral nervous system readily regenerate and innervate targets, those of the central nervous system do not. Therefore, enabling axon regeneration represents a crucial hurdle in regenerative medicine. The insulin-signaling and AKT/mTOR pathways are evolutionarily conserved mechanisms that promote axon regeneration. Utilizing a powerful model of advanced laser surgery to perform axotomy of single neurons within adult Caenorhabditis elegans, I have identified O-linked N-beta-acetylglucosamine (O-GlcNAc) post-translational modifications as a novel regulator of axon regeneration. Loss-of-function mutations in the O-GlcNAc Transferase, the enzyme that adds O- GlcNAc to target protein serines/threonines, significantly enhances axon regeneration. Astonishingly, loss-of- function mutations in the O-GlcNAcase, the enzyme that removes O-GlcNAc, also enhances regeneration. This counterintuitive result suggests that these enzymes act in independent pathways to regulate regeneration.
The aims of this proposal are to: 1. Determine how decreased O-GlcNAcylation in neurons increases axon regeneration through the AKT/mTOR pathway. 2. Determine how increasing O-GlcNAcylation enhances regeneration through the insulin-signaling pathway. This will be done by utilizing the power of C. elegans genetics and mouse neuronal cultures to pinpoint where and how O-GlcNAcylation is acting. Pharmacological analysis will further define the role of O-GlcNAcylation and identify potential therapeutic targets. This proposal will significantly advance the field of axon regeneration by defining a novel cellular mechanism where by O- GlcNAc modifications act as critical modulators of axon regeneration.
Utilizing in vivo laser surgery, the powerful genetic tools of C. elegans, and mammalian neuronal culture, this work will examine the influence of O-GlcNAc post-translational modifications on insulin- signaling and AKT/mTOR mediated axon regeneration. This work will pave the way for novel therapeutic targets in axon regeneration by modulating O-GlcNAc levels.
