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Temporal requirement for high SMN expression in SMA mice.

Spinal muscular atrophy (SMA) is caused by loss of the survival motor neuron 1 gene (SMN1) and retention of the SMN2 gene, resulting in reduced SMN. SMA mice can be rescued with high expression of SMN in neurons, but when is this high expression required? We have developed a SMA mouse with inducible expression of SMN to address the temporal requirement for high SMN expression. Both embryonic and early postnatal induction of SMN resulted in a dramatic increase in survival with some mice living greater than 200 days. The mice had no marked motor deficits and neuromuscular junction (NMJ) function was near normal thus it appears that induction of SMN in postnatal SMA mice rescues motor function. Early postnatal SMN induction, followed by a 1-month removal of induction at 28 days of age, resulted in no morphological or electrophysiological abnormalities at the NMJ and no overt motor phenotype. Upon removal of SMN induction, five mice survived for just over 1 month and two female mice have survived past 8 months of age. We suggest that there is a postnatal period of time when high SMN levels are required. Furthermore, two copies of SMN2 provide the minimal amount of SMN necessary to maintain survival during adulthood. Finally, in the course of SMA, early induction of SMN is most efficacious.

Pubmed ID: 21672919

Authors

  • Le TT
  • McGovern VL
  • Alwine IE
  • Wang X
  • Massoni-Laporte A
  • Rich MM
  • Burghes AH

Journal

Human molecular genetics

Publication Data

September 15, 2011

Associated Grants

  • Agency: NINDS NIH HHS, Id: NS069476
  • Agency: NINDS NIH HHS, Id: P30 NS045758
  • Agency: NINDS NIH HHS, Id: P30NS045758
  • Agency: NICHD NIH HHS, Id: R01 HD060586
  • Agency: NICHD NIH HHS, Id: R01 HD060586
  • Agency: NINDS NIH HHS, Id: R01 NS038650
  • Agency: NINDS NIH HHS, Id: RC2 NS069476
  • Agency: NCRR NIH HHS, Id: UL1 RR025755

Mesh Terms

  • Animals
  • Disease Models, Animal
  • Female
  • Gene Expression
  • Humans
  • Male
  • Mice
  • Mice, Transgenic
  • Motor Activity
  • Muscular Atrophy, Spinal
  • Survival of Motor Neuron 1 Protein
  • Survival of Motor Neuron 2 Protein