SIRT1 overexpression ameliorates a mouse model of SOD1-linked amyotrophic lateral sclerosis via HSF1/HSP70i chaperone system

Seiji Watanabe, Natsumi Ageta-Ishihara, Shinji Nagatsu, Keizo Takao, Okiru Komine, Fumito Endo, Tsuyoshi Miyakawa, Hidemi Misawa, Ryosuke Takahashi, Makoto Kinoshita, Koji Yamanaka

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

Abstract

Background: Dominant mutations in superoxide dismutase 1 (SOD1) cause degeneration of motor neurons in a subset of inherited amyotrophic lateral sclerosis (ALS). The pathogenetic process mediated by misfolded and/or aggregated mutant SOD1 polypeptides is hypothesized to be suppressed by protein refolding. This genetic study is aimed to test whether mutant SOD1-mediated ALS pathology recapitulated in mice could be alleviated by overexpressing a longevity-related deacetylase SIRT1 whose substrates include a transcription factor heat shock factor 1 (HSF1), the master regulator of the chaperone system. Results: We established a line of transgenic mice that chronically overexpress SIRT1 in the brain and spinal cord. While inducible HSP70 (HSP70i) was upregulated in the spinal cord of SIRT1 transgenic mice (PrP-Sirt1), no neurological and behavioral alterations were detected. To test hypothetical benefits of SIRT1 overexpression, we crossbred PrP-Sirt1 mice with two lines of ALS model mice: A high expression line that exhibits a severe phenotype (SOD1G93A-H) or a low expression line with a milder phenotype (SOD1G93A-L). The Sirt1 transgene conferred longer lifespan without altering the time of symptomatic onset in SOD1G93A-L. Biochemical analysis of the spinal cord revealed that SIRT1 induced HSP70i expression through deacetylation of HSF1 and that SOD1G93A-L/PrP-Sirt1 double transgenic mice contained less insoluble SOD1 than SOD1G93A-L mice. Parallel experiments showed that Sirt1 transgene could not rescue a more severe phenotype of SOD1G93A-H transgenic mice partly because their HSP70i level had peaked out. Conclusions: The genetic supplementation of SIRT1 can ameliorate a mutant SOD1-linked ALS mouse model partly through the activation of the HSF1/HSP70i chaperone system. Future studies shall include testing potential benefits of pharmacological enhancement of the deacetylation activity of SIRT1 after the onset of the symptom.

Original languageEnglish
Article number62
JournalMolecular brain
Volume7
Issue number1
DOIs
Publication statusPublished - 2014 Aug 29

Keywords

  • Amyotrophic lateral sclerosis (ALS)
  • Cu/Zn-superoxide dismutase (SOD1)
  • Heat shock factor 1 (HSF1)
  • Heat shock protein (HSP)
  • Sirtuin 1 (SIRT1)
  • Systematic behavioral screening

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience

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