Journal Article

The utrophin A 5′-UTR drives cap-independent translation exclusively in skeletal muscles of transgenic mice and interacts with eEF1A2

P. Miura, A. Coriati, G. Bélanger, Y. De Repentigny, J. Lee, R. Kothary, M. Holcik and B.J. Jasmin

in Human Molecular Genetics

Volume 19, issue 7, pages 1211-1220
Published in print April 2010 | ISSN: 0964-6906
Published online January 2010 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/ddp591
The utrophin A 5′-UTR drives cap-independent translation exclusively in skeletal muscles of transgenic mice and interacts with eEF1A2

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The molecular mechanisms regulating expression of utrophin A are of therapeutic interest since upregulating its expression at the sarcolemma can compensate for the lack of dystrophin in animal models of Duchenne Muscular Dystrophy (DMD). The 5′-UTR of utrophin A has been previously shown to drive cap-independent internal ribosome entry site (IRES)-mediated translation in response to muscle regeneration and glucocorticoid treatment. To determine whether the utrophin A IRES displays tissue specific activity, we generated transgenic mice harboring control (CMV/βGAL/CAT) or utrophin A 5′-UTR (CMV/βGAL/UtrA/CAT) bicistronic reporter transgenes. Examination of multiple tissues from two CMV/βGAL/UtrA/CAT lines revealed that the utrophin A 5′-UTR drives cap-independent translation of the reporter gene exclusively in skeletal muscles and no other examined tissues. This expression pattern suggested that skeletal muscle-specific factors are involved in IRES-mediated translation of utrophin A. We performed RNA-affinity chromatography experiments combined with mass spectrometry to identify trans-factors that bind the utrophin A 5′-UTR and identified eukaryotic elongation factor 1A2 (eEF1A2). UV-crosslinking experiments confirmed the specificity of this interaction. Regions of the utrophin A 5′-UTR that bound eEF1A2 also mediated cap-independent translation in C2C12 muscle cells. Cultured cells lacking eEF1A2 had reduced IRES activity compared with cells overexpressing eEF1A2. Together, these results suggest an important role for eEF1A2 in driving cap-independent translation of utrophin A in skeletal muscle. The trans-factors and signaling pathways driving skeletal-muscle specific IRES-mediated translation of utrophin A could provide unique targets for developing pharmacological-based DMD therapies.

Journal Article.  6249 words.  Illustrated.

Subjects: Genetics and Genomics

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