Figure 3.

This figure illustrates how activity from the mTOR signaling pathway contributes to axon regeneration in the selected examples of retinal nerve damage (a) and spinal cord injury (b,c): (a) Concerning retinal nerve regeneration, mTOR activity enhances axon elongation and survival leading to functional regeneration. Signals that upregulate mTOR activity like PTEN inhibition, siRTP801, Pam₃Cys (pro-inflammatory signal), CNTF (ciliary neurotrophic factor) or IGF-1 lead to axon recovery. TOR-independent axon recovery exists however as rapamycin-treated PTEN-deleted neurons and Pam₃Cys untreated neurons still showed recovery. (b) For spinal cord injuries, mTORC1 activity in astrocytes hinders neuronal recovery with the formation of glial scars (gliosis). Growth factors like EGF (epidermal growth factor) can activate mTORC1. (c) On the contrary, mTORC1 signaling in hemisection spinal cord injuries promotes growth and functional regeneration.