AAV-mediated inhibition of ULK1 promotes axonal regeneration in the central nervous system in vitro and in vivo

Cell Death Dis. 2021 Feb 26;12(2):213. doi: 10.1038/s41419-021-03503-3.

Abstract

Axonal damage is an early step in traumatic and neurodegenerative disorders of the central nervous system (CNS). Damaged axons are not able to regenerate sufficiently in the adult mammalian CNS, leading to permanent neurological deficits. Recently, we showed that inhibition of the autophagic protein ULK1 promotes neuroprotection in different models of neurodegeneration. Moreover, we demonstrated previously that axonal protection improves regeneration of lesioned axons. However, whether axonal protection mediated by ULK1 inhibition could also improve axonal regeneration is unknown. Here, we used an adeno-associated viral (AAV) vector to express a dominant-negative form of ULK1 (AAV.ULK1.DN) and investigated its effects on axonal regeneration in the CNS. We show that AAV.ULK1.DN fosters axonal regeneration and enhances neurite outgrowth in vitro. In addition, AAV.ULK1.DN increases neuronal survival and enhances axonal regeneration after optic nerve lesion, and promotes long-term axonal protection after spinal cord injury (SCI) in vivo. Interestingly, AAV.ULK1.DN also increases serotonergic and dopaminergic axon sprouting after SCI. Mechanistically, AAV.ULK1.DN leads to increased ERK1 activation and reduced expression of RhoA and ROCK2. Our findings outline ULK1 as a key regulator of axonal degeneration and regeneration, and define ULK1 as a promising target to promote neuroprotection and regeneration in the CNS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy-Related Protein-1 Homolog / genetics
  • Autophagy-Related Protein-1 Homolog / metabolism*
  • Axons / metabolism*
  • Axons / pathology
  • Cells, Cultured
  • Dependovirus / genetics*
  • Disease Models, Animal
  • Dopaminergic Neurons / metabolism
  • Dopaminergic Neurons / pathology
  • Down-Regulation
  • Female
  • Gene Transfer Techniques*
  • Genetic Vectors*
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Nerve Regeneration*
  • Neuronal Outgrowth
  • Optic Nerve / metabolism*
  • Optic Nerve / pathology
  • Optic Nerve Injuries / genetics
  • Optic Nerve Injuries / metabolism
  • Optic Nerve Injuries / pathology
  • Optic Nerve Injuries / therapy*
  • Rats
  • Rats, Wistar
  • Serotonergic Neurons / metabolism
  • Serotonergic Neurons / pathology
  • Spinal Cord / metabolism*
  • Spinal Cord / pathology
  • Spinal Cord Injuries / genetics
  • Spinal Cord Injuries / metabolism
  • Spinal Cord Injuries / pathology
  • Spinal Cord Injuries / therapy*
  • Time Factors
  • rho GTP-Binding Proteins / metabolism
  • rho-Associated Kinases / metabolism

Substances

  • Autophagy-Related Protein-1 Homolog
  • ROCK2 protein, rat
  • ULK1 protein, rat
  • rho-Associated Kinases
  • Mitogen-Activated Protein Kinase 3
  • RhoA protein, rat
  • rho GTP-Binding Proteins