Tetraspanin CD82 Associates with Trafficking Vesicle in Muscle Cells and Binds to Dysferlin and Myoferlin.

Tetraspanins organize protein complexes at the cell membrane and are responsible for assembling diverse binding partners in changing cellular states. Tetraspanin CD82 is a useful cell surface marker for prospective isolation of human myogenic progenitors and its expression is decreased in Duchenne muscular dystrophy (DMD) cell lines. The function of CD82 in skeletal muscle remains elusive, partly because the binding partners of this tetraspanin in muscle cells have not been identified.

Tandem duplication within the DMD gene in Labrador retrievers with a mild clinical phenotype.

A form of dystrophinopathy with mild or subclinical neuromuscular signs has been previously reported in a family of Labrador retrievers. Markedly and persistently elevated creatine kinase activity was first noted at 6 months of age. Skeletal muscle biopsies revealed a dystrophic phenotype, with dystrophin non-detectable on western blotting and immunohistochemical staining, and with increased utrophin expression.

A limb-girdle muscular dystrophy 2I model of muscular dystrophy identifies corrective drug compounds for dystroglycanopathies.

Zebrafish are a powerful tool for studying muscle function owing to their high numbers of offspring, low maintenance costs, evolutionarily conserved muscle functions, and the ability to rapidly take up small molecular compounds during early larval stages. Fukutin-related protein (FKRP) is a putative protein glycosyltransferase that functions in the Golgi apparatus to modify sugar chain molecules of newly translated proteins. Patients with mutations in the FKRP gene can have a wide spectrum of clinical symptoms with varying muscle, eye, and brain pathologies depending on the location of the mutation in the FKRP protein.

Repression of phosphatidylinositol transfer protein α ameliorates the pathology of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disease caused by X-linked inherited mutations in the () gene. Absence of dystrophin protein from the sarcolemma causes severe muscle degeneration, fibrosis, and inflammation, ultimately leading to cardiorespiratory failure and premature death. Although there are several promising strategies under investigation to restore dystrophin protein expression, there is currently no cure for DMD, and identification of genetic modifiers as potential targets represents an alternative therapeutic strategy.

Jagged 1 Rescues the Duchenne Muscular Dystrophy Phenotype.

Duchenne muscular dystrophy (DMD), caused by mutations at the dystrophin gene, is the most common form of muscular dystrophy. There is no cure for DMD and current therapeutic approaches to restore dystrophin expression are only partially effective. The absence of dystrophin in muscle results in dysregulation of signaling pathways, which could be targets for disease therapy and drug discovery.

The Pathogenesis and Therapy of Muscular Dystrophies.

Current molecular genomic approaches to human genetic disorders have led to an explosion in the identification of the genes and their encoded proteins responsible for these disorders. The identification of the gene altered by mutations in Duchenne and Becker muscular dystrophy was one of the earliest examples of this paradigm. The nearly 30 years of research partly outlined here exemplifies the road that similar current gene discovery protocols will be expected to travel, albeit much more rapidly owing to improved diagnosis of genetic disorders and an understanding of the spectrum of mutations thought to cause them.

Muscular dystrophy in a family of Labrador Retrievers with no muscle dystrophin and a mild phenotype.

Animal models of dystrophin deficient muscular dystrophy, most notably canine X-linked muscular dystrophy, play an important role in developing new therapies for human Duchenne muscular dystrophy. Although the canine disease is a model of the human disease, the variable severity of clinical presentations in the canine may be problematic for pre-clinical trials, but also informative. Here we describe a family of Labrador Retrievers with three generations of male dogs having markedly increased serum creatine kinase activity, absence of membrane dystrophin, but with undetectable clinical signs of muscle weakness.

MicroRNA-486-dependent modulation of DOCK3/PTEN/AKT signaling pathways improves muscular dystrophy-associated symptoms.

Duchenne muscular dystrophy (DMD) is caused by mutations in the gene encoding dystrophin, which results in dysfunctional signaling pathways within muscle. Previously, we identified microRNA-486 (miR-486) as a muscle-enriched microRNA that is markedly reduced in the muscles of dystrophin-deficient mice (Dmdmdx-5Cv mice) and in DMD patient muscles. Here, we determined that muscle-specific transgenic overexpression of miR-486 in muscle of Dmdmdx-5Cv mice results in reduced serum creatine kinase levels, improved sarcolemmal integrity, fewer centralized myonuclei, increased myofiber size, and improved muscle physiology and performance.

A defect in the RNA-processing protein HNRPDL causes limb-girdle muscular dystrophy 1G (LGMD1G).

Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of genetically determined muscle disorders with a primary or predominant involvement of the pelvic or shoulder girdle musculature. More than 20 genes with autosomal recessive (LGMD2A to LGMD2Q) and autosomal dominant inheritance (LGMD1A to LGMD1H) have been mapped/identified to date. Mutations are known for six among the eight mapped autosomal dominant forms: LGMD1A (myotilin), LGMD1B (lamin A/C), LGMD1C (caveolin-3), LGMD1D (desmin), LGMD1E (DNAJB6), and more recently for LGMD1F (transportin-3).

Systemic delivery of human mesenchymal stromal cells combined with IGF-1 enhances muscle functional recovery in LAMA2 dy/2j dystrophic mice.

The combination of cell therapy with growth factors could be a useful approach to treat progressive muscular dystrophies. Here, we demonstrate, for the first time, that IGF-1 considerably enhances the myogenesis of human umbilical cord (UC) mesenchymal stromal cells (MSCs) in vitro and that IGF-1 enhances interaction and restoration of dystrophin expression in co-cultures of MSCs and muscle cells from Duchenne patients. In vivo studies showed that human MSCs were able to reach the skeletal muscle of LAMA2(dy/2j) dystrophic mice, through systemic delivery, without immunosuppression.

Preclinical studies with umbilical cord mesenchymal stromal cells in different animal models for muscular dystrophy.

Umbilical cord mesenchymal stromal cells (MSC) have been widely investigated for cell-based therapy studies as an alternative source to bone marrow transplantation. Umbilical cord tissue is a rich source of MSCs with potential to derivate at least muscle, cartilage, fat, and bone cells in vitro. The possibility to replace the defective muscle cells using cell therapy is a promising approach for the treatment of progressive muscular dystrophies (PMDs), independently of the specific gene mutation.

Gene expression profile of mesenchymal stem cells from paired umbilical cord units: cord is different from blood.

Mesenchymal stem cells (MSC) are multipotent cells which can be obtained from several adult and fetal tissues including human umbilical cord units. We have recently shown that umbilical cord tissue (UC) is richer in MSC than umbilical cord blood (UCB) but their origin and characteristics in blood as compared to the cord remains unknown. Here we compared, for the first time, the exonic protein-coding and intronic noncoding RNA (ncRNA) expression profiles of MSC from match-paired UC and UCB samples, harvested from the same donors, processed simultaneously and under the same culture conditions.

Ringo: discordance between the molecular and clinical manifestation in a golden retriever muscular dystrophy dog.

Of the various genetic homologues to Duchenne Muscular Dystrophy (DMD), the Golden Retriever Muscular Dystrophy (GRMD) dog, which presents a variable but usually severe and progressive muscle weakness, has the closest relevance to DMD in both clinical severity and histopathological change. Among 77 GRMD dogs born in our colony in Brazil, we have identified a very mildly affected dog, Ringo, born July 2003. Among his descendants, at least one male, Suflair, is also showing a mild course.

Mesenchymal stem cells derived from canine umbilical cord vein--a novel source for cell therapy studies.

The canine model provides a large animal system to evaluate many treatment modalities using stem cells (SCs). However, only bone marrow (BM) protocols have been widely used in dogs for preclinical approaches. BM donation consists of an invasive procedure and the number and differentiation potential of its mesenchymal stem cells (MSCs) decline with age.

Stem cells from umbilical cord blood do have myogenic potential, with and without differentiation induction in vitro.

The dystrophin gene, located at Xp21, codifies dystrophin, which is part of a protein complex responsible for the membrane stability of muscle cells. Its absence on muscle causes Duchenne Muscular Dystrophy (DMD), a severe disorder, while a defect of muscle dystrophin causes Becker Muscular Dystrophy (DMB), a milder disease. The replacement of the defective muscle through stem cells transplantation is a possible future treatment for these patients.

Muscle protein alterations in LGMD2I patients with different mutations in the Fukutin-related protein gene.

Fukutin-related protein (FKRP) is a protein involved in the glycosylation of cell surface molecules. Pathogenic mutations in the FKRP gene cause both the more severe congenital muscular dystrophy Type 1C and the milder Limb-Girdle Type 2I form (LGMD2I). Here we report muscle histological alterations and the analysis of 11 muscle proteins: dystrophin, four sarcoglycans, calpain 3, dysferlin, telethonin, collagen VI, alpha-DG, and alpha2-laminin, in muscle biopsies from 13 unrelated LGMD2I patients with 10 different FKRP mutations.

Early transplantation of human immature dental pulp stem cells from baby teeth to golden retriever muscular dystrophy (GRMD) dogs: Local or systemic?

Background: The golden retriever muscular dystrophy (GRMD) dogs represent the best available animal model for therapeutic trials aiming at the future treatment of human Duchenne muscular dystrophy (DMD). We have obtained a rare litter of six GRMD dogs (3 males and 3 females) born from an affected male and a carrier female which were submitted to a therapeutic trial with adult human stem cells to investigate their capacity to engraft into dogs muscles by local as compared to systemic injection without any immunosuppression.

Methods: Human Immature Dental Pulp Stem Cells (hIDPSC) were transplanted into 4 littermate dogs aged 28 to 40 days by either arterial or muscular injections.

SJL dystrophic mice express a significant amount of human muscle proteins following systemic delivery of human adipose-derived stromal cells without immunosuppression.

Limb-girdle muscular dystrophies (LGMDs) are a heterogeneous group of disorders characterized by progressive degeneration of skeletal muscle caused by the absence of or defective muscular proteins. The murine model for limb-girdle muscular dystrophy 2B (LGMD2B), the SJL mice, carries a deletion in the dysferlin gene that causes a reduction in the protein levels to 15% of normal. The mice show muscle weakness that begins at 4-6 weeks and is nearly complete by 8 months of age.

Human multipotent adipose-derived stem cells restore dystrophin expression of Duchenne skeletal-muscle cells in vitro.

Background Information: DMD (Duchenne muscular dystrophy) is a devastating X-linked disorder characterized by progressive muscle degeneration and weakness. The use of cell therapy for the repair of defective muscle is being pursued as a possible treatment for DMD. Mesenchymal stem cells have the potential to differentiate and display a myogenic phenotype in vitro.

Multipotent stem cells from umbilical cord: cord is richer than blood!

The identification of mesenchymal stem cell (MSC) sources that are easily obtainable is of utmost importance. Several studies have shown that MSCs could be isolated from umbilical cord (UC) units. However, the presence of MSCs in umbilical cord blood (UCB) is controversial.

A novel missense mutation in the caveolin-3 gene in rippling muscle disease.

Rippling muscle disease (RMD) is a benign myopathy with symptoms and signs of muscular hyperirritability. We report a 17-year-old patient who presented with muscular hypertrophy, local mounding on percussion, and a rippling phenomenon. Needle electromyography showed electrical silence during the rippling phenomenon.

Asymptomatic carriers for homozygous novel mutations in the FKRP gene: the other end of the spectrum.

Autosomal recessive limb-girdle muscular dystrophy linked to 19q13.3 (LGMD2I) was recently related to mutations in the fukutin-related protein gene (FKRP) gene. Pathogenic changes in the same gene were detected in congenital muscular dystrophy patients (MDC1C), a severe disorder.