Necroptosis is dispensable for motor neuron degeneration in a mouse model of ALS

Cell Death Differ. 2020 May;27(5):1728-1739. doi: 10.1038/s41418-019-0457-8. Epub 2019 Nov 19.

Abstract

Motor neuron degeneration in amyotrophic lateral sclerosis (ALS) is proposed to occur by necroptosis, an inflammatory form of regulated cell death. Prior studies implicated necroptosis in ALS based on accumulation of necroptotic markers in affected tissues of patients and mouse models, and amelioration of disease in mutant superoxide dismutase 1 (SOD1G93A) mice with inhibition of the upstream necroptotic mediators, receptor interacting protein kinase 1 (RIPK1), and RIPK3. To definitively address the pathogenic role of necroptosis in ALS, we genetically ablated the critical terminal executioner of necroptosis, mixed lineage kinase domain-like protein (MLKL), in SOD1G93A mice. Disease onset, progression, and survival were not affected in SOD1G93A mice lacking MLKL. Motor neuron degeneration and activation of neuroinflammatory cells, astrocytes, and microglia, were independent of MLKL expression in SOD1G93A mice. While RIPK1 accumulation occurred in spinal cords of SOD1G93A mice in late stage disease, RIPK3 and MLKL expression levels were not detected in central nervous system tissues from normal or SOD1G93A mice at any disease stage. These findings demonstrate that necroptosis does not play an important role in motor neuron death in ALS, which may limit the potential of therapeutic targeting of necroptosis in the treatment of neurological disorders.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyotrophic Lateral Sclerosis / pathology*
  • Animals
  • Brain / pathology
  • Disease Models, Animal
  • Disease Progression
  • Humans
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Motor Neurons / metabolism
  • Motor Neurons / pathology*
  • Necroptosis*
  • Nerve Degeneration / pathology*
  • Neuroglia / metabolism
  • Neuroglia / pathology
  • Protein Kinases / metabolism
  • Receptor-Interacting Protein Serine-Threonine Kinases / metabolism
  • Spinal Cord / pathology
  • Superoxide Dismutase / metabolism
  • Up-Regulation

Substances

  • Superoxide Dismutase
  • MLKL protein, mouse
  • Protein Kinases
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • Ripk1 protein, mouse