Duchenne muscular dystrophy caused by a frame-shift mutation in the acceptor splice site of intron 26

Background: The dystrophin gene is the one of the largest described in human beings and mutations associated to this gene are responsible for Duchenne or Becker muscular dystrophies. Case Presentation: Here we describe a nucleotide substitution in the acceptor splice site of intron 26 (c.3604-1G > C) carried by a 6-year-old boy who presented with a history of progressive proximal muscle weakness and elevated serum creatine kinase levels. RNA analysis showed that the first two nucleotides of the mutated intron 26 (AC) were not recognized by the splicing machinery and a new splicing site was created within exon 27, generating a premature stop codon and avoiding protein translation. Conclusions: The evaluation of the pathogenic effect of the mutation by mRNA analysis will be useful in the optics of an antisense oligonucleotides (AON)-based therapy

Hmgb3 is regulated by microrna-206 during muscle regeneration.

MicroRNAs (miRNAs) have been recently involved in most of human diseases as targets for potential strategies to rescue the pathological phenotype. Since the skeletal muscle is a spread-wide highly differentiated and organized tissue, rescue of severely compromised muscle still remains distant from nowadays. For this reason, we aimed to identify a subset of miRNAs major involved in muscle remodelling and regeneration by analysing the miRNA-profile of single fibres isolated from dystrophic muscle, which was here considered as a model of chronic damage

Stem Cell Therapies to Treat Muscular Dystrophy : Progress to Date

Muscular dystrophies are heritable, heterogeneous neuromuscular disorders and include Duchenne and Becker muscular dystrophies (DMD and BMD, respectively). DMD patients exhibit progressive muscle weakness and atrophy followed by exhaustion of muscular regenerative capacity, fibrosis, and eventually disruption of the muscle tissue architecture. In-frame mutations in the dystrophin gene lead to expression of a partially functional protein, resulting in the milder BMD. No effective therapies are available at present. Cell-based therapies have been attempted in an effort to promote muscle regeneration, with the hope that the host cells would repopulate the muscle and improve muscle function and pathology. Injection of adult myoblasts has led to the development of new muscle fibers, but several limitations have been identified, such as poor cell survival and limited migratory ability. As an alternative to myoblasts, stem cells were considered preferable for therapeutic applications because of their capacity for self-renewal and differentiation potential. In recent years, encouraging results have been obtained with adult stem cells to treat human diseases such as leukemia, Parkinson's disease, stroke, and muscular dystrophies. Embryonic stem cells (ESCs) can be derived from mammalian embryos in the blastocyst stage, and because they can differentiate into a wide range of specialized cells, they hold potential for use in treating almost all human diseases. Several ongoing studies focus on this possibility, evaluating differentiation of specific cell lines from human ESCs (hESCs) as well as the potential tumorigenicity of hESCs. The most important limitation with using hESCs is that it requires destruction of human blastocysts or embryos. Conversely, adult stem cells have been identified in various tissues, where they serve to maintain, generate, and replace terminally differentiated cells within their specific tissue as the need arises for cell turnover or from tissue injury. Moreover, these cells can participate in regeneration of more than just their specific tissue type. Here we describe multiple types of muscle- and fetal-derived myogenic stem cells, their characterization, and their possible use in treating muscular dystrophies such as DMD and BMD. We also emphasize that the most promising possibility for the management and therapy of DMD and BMD is a combination of different approaches, such as gene and stem cell therapy

Differential Activation of CD20-related Signaling Pathways Results in distinct differentiation behaviour of normal and DMD circulating CD133+ Stem Cells

Invited speake

Characterization of muscle-specific expression of miRNAs in duchenne muscular dystrophy

The miRNAs are a class of highly-conserved and tissue-specific non-coding RNAs involved in post transcriptional regulation. Animal miRNAs typically form imperfectly base-pair duplexes with microRNA response element (MRE) in target mRNAs and this interaction inhibits translation of the target mRNA. In this study, we wanted to clarify the role of muscle-specific miRNAs in the pathogenesis of Duchenne muscular dystrophy (DMD). DMD is a muscle degenerative disease caused by a mutation in the gene encoding dystrophin. The molecular mechanisms responsible for the pathogenesis are not completely clear but recent reports demonstrated an involvement of some miRNAs in muscle development. Three miRNAs (miR-1, miR-133 and miR-206) are muscle-specific and seem to be involved in muscle proliferation and/or differentiation: they are all switched on during in vitro induced maturation of myoblast to myotube. More specifically it has been demonstrated that miR-1 induces muscle proliferation through inhibition of histone deacetylase 4 (HDAC4); miR-133 induces muscle differentiation through inhibition of serum response factor (SRF) and miR-206 induces muscle differentiation through the inhibition of three different target, Utrophyn (Utr), the largest subunit of Dna Pol alpha (Pola1) and Connexin 43 (Cx43). Northern blot with DIG-labelled probes and real-time PCR were used to evaluate the presence and the level of expression of miR-1, miR-133 and miR-206 in human fetal and adult muscle obtained from normal and DMD subjects. We characterized the differences between adult and fetal tissues inside the same clinical group, to see if the pattern of miRNA expression is time-dependent, and between normal and DMD tissues, in order to understand the involvement of these miRNAs in the disease. Preliminary results indicate different expression of miRNA between normal and DMD subjects. These data suggest a possible miRNA implications in the muscle damage of Duchenne muscular dystrophy