Sacs knockout mice present pathophysiological defects underlying autosomal recessive spastic ataxia of Charlevoix-Saguenay

Hum Mol Genet. 2015 Feb 1;24(3):727-39. doi: 10.1093/hmg/ddu491. Epub 2014 Sep 26.


Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS [MIM 270550]) is an early-onset neurodegenerative disorder caused by mutations in the SACS gene. Over 170 SACS mutations have been reported worldwide and are thought to cause loss of function of sacsin, a poorly characterized and massive 520 kDa protein. To establish an animal model and to examine the pathophysiological basis of ARSACS, we generated Sacs knockout (Sacs(-/-)) mice. Null animals displayed an abnormal gait with progressive motor, cerebellar and peripheral nerve dysfunctions highly reminiscent of ARSACS. These clinical features were accompanied by an early onset, progressive loss of cerebellar Purkinje cells followed by spinal motor neuron loss and peripheral neuropathy. Importantly, loss of sacsin function resulted in abnormal accumulation of non-phosphorylated neurofilament (NF) bundles in the somatodendritic regions of vulnerable neuronal populations, a phenotype also observed in an ARSACS brain. Moreover, motor neurons cultured from Sacs(-/-) embryos exhibited a similar NF rearrangement with significant reduction in mitochondrial motility and elongated mitochondria. The data points to alterations in the NF cytoskeleton and defects in mitochondrial dynamics as the underlying pathophysiological basis of ARSACS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Disease Models, Animal
  • Heat-Shock Proteins / genetics*
  • Heat-Shock Proteins / metabolism
  • Humans
  • Intermediate Filaments / pathology
  • Mice
  • Mice, Knockout
  • Mitochondria / pathology*
  • Motor Neurons / cytology
  • Motor Neurons / pathology*
  • Muscle Spasticity / genetics
  • Muscle Spasticity / physiopathology*
  • Purkinje Cells / metabolism
  • Purkinje Cells / pathology*
  • Pyramidal Tracts / pathology
  • Spine / pathology
  • Spinocerebellar Ataxias / congenital*
  • Spinocerebellar Ataxias / genetics
  • Spinocerebellar Ataxias / physiopathology
  • Tissue Culture Techniques


  • Heat-Shock Proteins
  • Sacs protein, mouse

Supplementary concepts

  • Spastic ataxia Charlevoix-Saguenay type