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Neuron. 2009 Aug 13;63(3):316-28. doi: 10.1016/j.neuron.2009.07.019.

Overexpression of IGF-1 in muscle attenuates disease in a mouse model of spinal and bulbar muscular atrophy.

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1
Neurogenetics Branch, NINDS, NIH, Bethesda, MD 20892, USA.

Abstract

Expansion of a polyglutamine tract in the androgen receptor (AR) causes spinal and bulbar muscular atrophy (SBMA). We previously showed that Akt-mediated phosphorylation of AR reduces ligand binding and attenuates the mutant AR toxicity. Here, we show that in culture insulin-like growth factor 1 (IGF-1) reduces AR aggregation and increases AR clearance via the ubiquitin-proteasome system through phosphorylation of AR by Akt. In vivo, SBMA transgenic mice overexpressing a muscle-specific isoform of IGF-1 selectively in skeletal muscle show evidence of increased Akt activation and AR phosphorylation and decreased AR aggregation. Augmentation of IGF-1/Akt signaling rescues behavioral and histopathological abnormalities, extends the life span, and reduces both muscle and spinal cord pathology of SBMA mice. This study establishes IGF-1/Akt-mediated inactivation of mutant AR as a strategy to counteract disease in vivo and demonstrates that skeletal muscle is a viable target tissue for therapeutic intervention in SBMA.

PMID:
19679072
PMCID:
PMC2735765
DOI:
10.1016/j.neuron.2009.07.019
[Indexed for MEDLINE]
Free PMC Article

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