Molecular cloning and characterization of dystrophin and Dp71, two products of the Duchenne Muscular Dystrophy gene, in zebrafish

Dystrophin, the protein responsible for Duchenne Muscular Dystrophy (DMD), plays a critical role in the maintenance of the muscle membrane integrity. There are several forms of dystrophin derived from the DMD gene by alternat ive promoter usage. In addition to full-length dystrophin Dp427), four shor ter transcripts have been identified: Dp260, Dp140, Dp116 and Dp71. The fun ctional role played by the different products of the DMD gene is not yet de termined. To get insight into the function of dystrophin and related produc ts, we have investigated the presence of dystrophin in zebrafish. This choi ce takes advantage of large-scale mutagenesis screens in zebrafish, which h ave led to the identification of several mutants with motility defects. The identification and characterization of the genes affected by these mutatio ns is likely to provide relevant information for the understanding of the m olecular mechanisms of muscle development and function. Two cDNA clones enc oding the homologues of dystrophin and Dp71 in zebrafish were identified an d characterized. Both transcripts exhibit a high degree of sequence homolog y with the dystrophin and Dp71 proteins described in higher vertebrates. In addition, three alternative spliced transcripts that occur at the C-termin al end of the zebrafish DMD gene have been identified. These transcripts ex hibit different patterns of tissue expression. We have also determined the chromosomal localization of dystrophin on the radiation hybrid map of the z ebrafish genome. Our results indicate that the dystrophin gene is localized to linkage group one. Altogether, these results give new insights on the p hysiological role played by dystrophin and related proteins, and provide ne w tools for the identification of mutated genes associated with muscle defe cts in zebrafish. (C) 2001 Published by Elsevier Science B.V.