Muscle-specific alternative splicing of myotubularin-related 1 gene is impaired in DM1 muscle cells.
Fiche publication
Date publication
septembre 2002
Journal
Human molecular genetics
Auteurs
Membres identifiés du Cancéropôle Est :
Pr MANDEL Jean-Louis, Mr LEROUGE Thierry
Tous les auteurs :
Buj-Bello A, Furling D, Tronchère H, Laporte J, Lerouge T, Butler-Browne GS, Mandel JL
Lien Pubmed
Résumé
The myotubularin-related 1 (MTMR1) gene belongs to a highly conserved family of eucaryotic phosphatases, with at least 11 members in humans. The founder member of this gene family, MTM1, is mutated in X-linked myotubular myopathy, a severe congenital disorder that affects skeletal muscle, and codes for myotubularin, a specific phosphatidylinositol 3-phosphate [PI(3)P] phosphatase. MTM1 and MTMR1 are adjacent on the X chromosome, and the corresponding proteins share 59% sequence identity. In the present study, we investigated the putative role of MTMR1 in myogenesis by analysing its expression pattern in muscle cells during differentiation and in skeletal muscle throughout development. We have identified three novel coding exons in the MTMR1 intron 2 that are conserved between mouse and human, are alternatively spliced, and give rise to six mRNA isoforms. One of the transcripts is muscle-specific and is induced during myogenesis both in vitro and in vivo, and represents the major isoform in adult skeletal muscle. We show that the two main MTMR1 protein muscular isoforms, like myotubularin, efficiently dephosphorylate PI(3)P in vitro. We have also analysed whether MTMR1 alternative splicing is affected in skeletal muscle cells derived from patients with congenital myotonic dystrophy (cDM1), in which mRNA splicing disturbances of specific genes are thought to constitute an important pathogenic mechanism. We found a striking reduction in the level of the muscle-specific isoform and the appearance of an abnormal MTMR1 transcript in differentiated cDM1 muscle cells in culture and in skeletal muscle from cDM1 patients. Our results suggest that MTMR1 plays a role in muscle formation and represents a novel target for abnormal mRNA splicing in myotonic dystrophy.
Mots clés
Alternative Splicing, Animals, Exons, Fluorescent Antibody Technique, Gene Expression Regulation, Humans, Isoenzymes, genetics, Mice, Muscle, Skeletal, metabolism, Myotonic Dystrophy, genetics, Organ Specificity, Phosphoric Monoester Hydrolases, genetics, Precipitin Tests, Protein Tyrosine Phosphatases, genetics, Protein Tyrosine Phosphatases, Non-Receptor, Sequence Analysis, DNA
Référence
Hum. Mol. Genet.. 2002 Sep;11(19):2297-307