MBNL142 and MBNL143 gene isoforms, overexpressed in DM1-patient muscle, encode for nuclear proteins interacting with Src family kinases.

A Botta, A Malena, E Tibaldi, L Rocchi, E Loro, E Pena, L Cenci, E Ambrosi, M C Bellocchi, M A Pagano, G Novelli, G Rossi, H L Monaco, E Gianazza, B Pantic, V Romeo, O Marin, A M Brunati, L Vergani

Cell death & disease 2013 Aug 15

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Myotonic dystrophy type-1 (DM1) is the most prevalent form of muscular dystrophy in adults. This disorder is an RNA-dominant disease, caused by expansion of a CTG repeat in the DMPK gene that leads to a misregulation in the alternative splicing of pre-mRNAs. The longer muscleblind-like-1 (MBNL1) transcripts containing exon 5 and the respective protein isoforms (MBNL142-43) were found to be overexpressed in DM1 muscle and localized exclusively in the nuclei. In vitro assays showed that MBNL142-43 bind the Src-homology 3 domain of Src family kinases (SFKs) via their proline-rich motifs, enhancing the SFK activity. Notably, this association was also confirmed in DM1 muscle and myotubes. The recovery, mediated by an siRNA target to Ex5-MBNL142-43, succeeded in reducing the nuclear localization of both Lyn and MBNL142-43 proteins and in decreasing the level of tyrosine phosphorylated proteins. Our results suggest an additional molecular mechanism in the DM1 pathogenesis, based on an altered phosphotyrosine signalling pathway.

Citation

A Botta, A Malena, E Tibaldi, L Rocchi, E Loro, E Pena, L Cenci, E Ambrosi, M C Bellocchi, M A Pagano, G Novelli, G Rossi, H L Monaco, E Gianazza, B Pantic, V Romeo, O Marin, A M Brunati, L Vergani. MBNL142 and MBNL143 gene isoforms, overexpressed in DM1-patient muscle, encode for nuclear proteins interacting with Src family kinases. Cell death & disease. 2013 Aug 15;4:e770