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PLoS Genet. 2013 Apr;9(4):e1003445. doi: 10.1371/journal.pgen.1003445. Epub 2013 Apr 18.

Smaug/SAMD4A restores translational activity of CUGBP1 and suppresses CUG-induced myopathy.

Author information

1
Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America.

Abstract

We report the identification and characterization of a previously unknown suppressor of myopathy caused by expansion of CUG repeats, the mutation that triggers Myotonic Dystrophy Type 1 (DM1). We screened a collection of genes encoding RNA-binding proteins as candidates to modify DM1 pathogenesis using a well established Drosophila model of the disease. The screen revealed smaug as a powerful modulator of CUG-induced toxicity. Increasing smaug levels prevents muscle wasting and restores muscle function, while reducing its function exacerbates CUG-induced phenotypes. Using human myoblasts, we show physical interactions between human Smaug (SMAUG1/SMAD4A) and CUGBP1. Increased levels of SMAUG1 correct the abnormally high nuclear accumulation of CUGBP1 in myoblasts from DM1 patients. In addition, augmenting SMAUG1 levels leads to a reduction of inactive CUGBP1-eIF2α translational complexes and to a correction of translation of MRG15, a downstream target of CUGBP1. Therefore, Smaug suppresses CUG-mediated muscle wasting at least in part via restoration of translational activity of CUGBP1.

PMID:
23637619
PMCID:
PMC3630084
DOI:
10.1371/journal.pgen.1003445
[Indexed for MEDLINE]
Free PMC Article

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