-
Frontiers in Physiology 2024Duchenne muscular dystrophy (DMD) is a fatal striated muscle degenerative disease. DMD is caused by loss of dystrophin protein, which results in sarcolemmal instability...
Duchenne muscular dystrophy (DMD) is a fatal striated muscle degenerative disease. DMD is caused by loss of dystrophin protein, which results in sarcolemmal instability and cycles of myofiber degeneration and regeneration. Pathology is exacerbated by overactivation of infiltrating immune cells and fibroblasts, which leads to chronic inflammation and fibrosis. Mineralocorticoid receptors (MR), a type of nuclear steroid hormone receptors, are potential therapeutic targets for DMD. MR antagonists show clinical efficacy on DMD cardiomyopathy and preclinical efficacy on skeletal muscle in DMD models. We have previously generated myofiber and myeloid MR knockout mouse models to dissect cell-specific functions of MR within dystrophic muscles. Here, we compared skeletal muscle gene expression from both knockouts to further define cell-type specific signaling downstream from MR. Myeloid MR knockout increased proinflammatory and profibrotic signaling, including numerous myofibroblast signature genes. was the most highly upregulated fibrotic gene in myeloid MR-knockout skeletal muscle and is a component of fibrosis in dystrophic skeletal muscle. Surprisingly, (), canonically a collagen crosslinker, was increased in both MR knockouts, but did not localize to fibrotic regions of skeletal muscle. Lox localized within myofibers, including only a region of quadriceps muscles. (), another Lox family member, was increased only in myeloid MR knockout muscle and localized specifically to fibrotic regions. This study suggests that MR signaling in the dystrophic muscle microenvironment involves communication between contributing cell types and modulates inflammatory and fibrotic pathways in muscle disease.
PubMed: 38737833
DOI: 10.3389/fphys.2024.1322729 -
Translational Lung Cancer Research Apr 2024The identification of prognostic biomarkers is crucial for guiding treatment strategies in mesothelioma patients. The Duchenne muscular dystrophy () gene and its...
BACKGROUND
The identification of prognostic biomarkers is crucial for guiding treatment strategies in mesothelioma patients. The Duchenne muscular dystrophy () gene and its specific transcripts have been associated with patient survival in various tumours. In this study, we aimed to investigate the prognostic potential of gene expression and its transcripts in mesothelioma patients.
METHODS
We analysed The Cancer Genome Atlas (TCGA) mesothelioma RNAseq, mutation, and clinical data to assess the association between gene expression and its transcripts (Dp427, Dp71 splice variants) and mesothelioma survival. We also evaluated the specific Dp71 transcript as a unique prognostic biomarker across mesothelioma subtypes. Additionally, we performed differential gene expression analysis between high and low gene/transcript expression groups.
RESULTS
The analysis included 57 epithelioid, 23 biphasic, two sarcomatoid, and five not otherwise specified (NOS) histological subtypes of mesothelioma samples. Univariate analysis revealed that high expression of the gene and its Dp71 transcript was significantly associated with shorter survival in mesothelioma patients (P0.003 and P<0.001, respectively). In a multivariate analysis, the association between Dp71 expression and survival remained significant [hazard ratio (HR) 2.29, 95% confidence interval (CI): 1.24-4.23, P0.008] across all mesothelioma patients, and also among patients with mesotheliomas without deep deletions (HR 3.58, 95% CI: 1.31-9.80, P0.01). Pathway analysis revealed enrichment of cell cycle (P3.01×10) and homologous recombination (P0.01) pathways in differentially expressed genes (DEGs) between high and low Dp71 groups. Furthermore, there were correlations between Dp71 transcript expression and tumour microenvironment (TME) cells, including a weak positive correlation with macrophages (R=0.32, P0.002) specifically M2 macrophages (R=0.34, P0.001).
CONCLUSIONS
Our findings indicate that the differential expression of specific transcripts is associated with poor survival in mesothelioma patients. The specific Dp71 transcript can serve as a potential biomarker for predicting patient survival in diverse histological subtypes of mesothelioma. Further studies are needed to understand the role of specific dystrophin transcripts in cancer and TME cells, and their implications in the pathogenesis and progression of mesothelioma. Identifying patients at risk of poor survival based on transcript expression can guide treatment strategies in mesothelioma, informing decisions regarding treatment intensity, follow-up schedules, eligibility for clinical trials, and ultimately, end-of-life care planning.
PubMed: 38736495
DOI: 10.21037/tlcr-24-28 -
Disease Models & Mechanisms Apr 2024Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene, resulting in the loss of dystrophin, a large cytosolic protein that links the cytoskeleton to...
Duchenne muscular dystrophy (DMD) is caused by mutations in the DMD gene, resulting in the loss of dystrophin, a large cytosolic protein that links the cytoskeleton to extracellular matrix receptors in skeletal muscle. Aside from progressive muscle damage, many patients with DMD also have neurological deficits of unknown etiology. To investigate potential mechanisms for DMD neurological deficits, we assessed postnatal oligodendrogenesis and myelination in the Dmdmdx mouse model. In the ventricular-subventricular zone (V-SVZ) stem cell niche, we found that oligodendrocyte progenitor cell (OPC) production was deficient, with reduced OPC densities and proliferation, despite a normal stem cell niche organization. In the Dmdmdx corpus callosum, a large white matter tract adjacent to the V-SVZ, we also observed reduced OPC proliferation and fewer oligodendrocytes. Transmission electron microscopy further revealed significantly thinner myelin, an increased number of abnormal myelin structures and delayed myelin compaction, with hypomyelination persisting into adulthood. Our findings reveal alterations in oligodendrocyte development and myelination that support the hypothesis that changes in diffusion tensor imaging seen in patients with DMD reflect developmental changes in myelin architecture.
Topics: Animals; Myelin Sheath; Oligodendroglia; Muscular Dystrophy, Duchenne; Mice, Inbred mdx; Cell Proliferation; Dystrophin; Corpus Callosum; Mice, Inbred C57BL; Mice; Oligodendrocyte Precursor Cells; Lateral Ventricles; Disease Models, Animal; Cell Differentiation; Male
PubMed: 38721692
DOI: 10.1242/dmm.050115 -
Neuromuscular Disorders : NMD Jun 2024Structural variants (SVs) are infrequently observed in Duchenne muscular dystrophy (DMD), a condition mainly marked by deletions and point mutations in the DMD gene. SVs...
Structural variants (SVs) are infrequently observed in Duchenne muscular dystrophy (DMD), a condition mainly marked by deletions and point mutations in the DMD gene. SVs in DMD remain difficult to reliably detect due to the limited SV-detection capacity of conventionally used short-read sequencing technology. Herein, we present a family, a boy and his mother, with clinical signs of muscular dystrophy, elevated creatinine kinase levels, and intellectual disability. A muscle biopsy from the boy showed dystrophin deficiency. Routine molecular techniques failed to detect abnormalities in the DMD gene, however, dystrophin mRNA transcripts analysis revealed an absence of exons 59 to 79. Subsequent long-read whole-genome sequencing identified a rare complex structural variant, a 77 kb novel intragenic inversion, and a balanced translocation t(X;1)(p21.2;p13.3) rearrangement within the DMD gene, expanding the genetic spectrum of dystrophinopathy. Our findings suggested that SVs should be considered in cases where conventional molecular techniques fail to identify pathogenic variants.
Topics: Muscular Dystrophy, Duchenne; Humans; Male; Translocation, Genetic; Dystrophin; Female; Chromosome Inversion; Adult; Child
PubMed: 38714145
DOI: 10.1016/j.nmd.2024.04.003 -
The Journal of Clinical Investigation May 2024Satellite cells, the stem cells of skeletal muscle tissue, hold a remarkable regeneration capacity and therapeutic potential in regenerative medicine. However, low...
Satellite cells, the stem cells of skeletal muscle tissue, hold a remarkable regeneration capacity and therapeutic potential in regenerative medicine. However, low satellite cell yield from autologous or donor-derived muscles hinders the adoption of satellite cell transplantation for the treatment of muscle diseases, including Duchenne muscular dystrophy (DMD). To address this limitation, here we investigated whether satellite cells can be derived in allogeneic or xenogeneic animal hosts. First, injection of CRISPR/Cas9-corrected mouse DMD-induced pluripotent stem cells (iPSCs) into mouse blastocysts carrying an ablation system of host satellite cells gave rise to intraspecies chimeras exclusively carrying iPSC-derived satellite cells. Furthermore, injection of genetically corrected DMD-iPSCs into rat blastocysts resulted in the formation of interspecies rat-mouse chimeras harboring mouse satellite cells. Remarkably, iPSC-derived satellite cells or derivative myoblasts produced in intraspecies or interspecies chimeras restored dystrophin expression in DMD mice following intramuscular transplantation, and contributed to the satellite cell pool. Collectively, this study demonstrates the feasibility of producing therapeutically competent stem cells across divergent animal species, raising the possibility of generating human muscle stem cells in large animals for regenerative medicine purposes.
PubMed: 38713532
DOI: 10.1172/JCI166998 -
JCI Insight May 2024Clinical trials delivering high doses of adeno-associated viruses (AAVs) expressing truncated dystrophin molecules (microdystrophins) are underway for Duchenne muscular...
Clinical trials delivering high doses of adeno-associated viruses (AAVs) expressing truncated dystrophin molecules (microdystrophins) are underway for Duchenne muscular dystrophy (DMD). We examined the efficiency and efficacy of this strategy with 4 microdystrophin constructs (3 in clinical trials and a variant of the largest clinical construct), in a severe mouse model of DMD, using AAV doses comparable with those in clinical trials. We achieved high levels of microdystrophin expression in striated muscles with cardiac expression approximately 10-fold higher than that observed in skeletal muscle. Significant, albeit incomplete, correction of skeletal muscle disease was observed. Surprisingly, a lethal acceleration of cardiac disease occurred with 2 of the microdystrophins. The detrimental cardiac effect appears to be caused by variable competition (dependent on microdystrophin design and expression level) between microdystrophin and utrophin at the cardiomyocyte membrane. There may also be a contribution from an overloading of protein degradation. The significance of these observations for patients currently being treated with AAV-microdystrophin therapies is unclear since the levels of expression being achieved in the DMD hearts are unknown. However, these findings suggest that microdystrophin treatments need to avoid excessively high levels of expression in the heart and that cardiac function should be carefully monitored in these patients.
Topics: Muscular Dystrophy, Duchenne; Animals; Genetic Therapy; Dystrophin; Mice; Dependovirus; Muscle, Skeletal; Disease Models, Animal; Utrophin; Humans; Genetic Vectors; Male; Mice, Inbred mdx; Myocytes, Cardiac
PubMed: 38713520
DOI: 10.1172/jci.insight.165869 -
BioRxiv : the Preprint Server For... Apr 2024Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive disease due to loss-of-function mutations in the gene. DMD-related skeletal muscle wasting is typified...
Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive disease due to loss-of-function mutations in the gene. DMD-related skeletal muscle wasting is typified by an aberrant immune response involving upregulation of TGFβ family of cytokines. We previously demonstrated that bone morphogenetic protein 4 (BMP4) is increased in DMD and BMP4 stimulation induces a 20-fold upregulation of transcription. However, the role of BMP4 in severely affected DMD skeletal muscle is unknown. We hypothesized that transcriptomic signatures in severely affected human DMD skeletal muscle are driven by BMP4 signaling. Transcriptomes from skeletal muscle biopsies of late-stage DMD vs. non-DMD controls and C2C12 muscle cells with or without BMP4 stimulation were generated by RNA-Seq and analyzed for single transcript differential expression as well as by Ingenuity Pathway Analysis and weighted gene co-expression network analyses. A total of 2,328 and 5,291 transcripts in the human muscle and C2C12 muscle cells, respectively, were differentially expressed. We identified an overlapping molecular signature of 1,027 genes dysregulated in DMD muscle that were induced in BMP4-stimulated C2C12 muscle cells. Highly upregulated DMD transcripts that overlapped with BMP4-stimulated C2C12 muscle cells included , and The DMD transcriptome was characterized by dysregulation of pathways involving immune function, extracellular matrix remodeling, and metabolic/mitochondrial function. In summary, we define a late-stage DMD skeletal muscle transcriptome that substantially overlaps with the BMP4-induced molecular signature in C2C12 muscle cells. This supports BMP4 as a disease-driving regulator of transcriptomic changes in late-stage DMD skeletal muscle and expands our understanding of the evolution of dystrophic signaling pathways and their associated gene networks that could be explored for therapeutic development.
PubMed: 38712206
DOI: 10.1101/2024.04.19.590266 -
Communications Biology May 2024Duchenne muscular dystrophy (DMD) is an intractable X-linked muscular dystrophy caused by mutations in the DMD gene. While many animal models have been used to study the...
Duchenne muscular dystrophy (DMD) is an intractable X-linked muscular dystrophy caused by mutations in the DMD gene. While many animal models have been used to study the disease, translating findings to humans has been challenging. Microminipigs, with their pronounced physiological similarity to humans and notably compact size amongst pig models, could offer a more representative model for human diseases. Here, we accomplished precise DMD modification in microminipigs by co-injecting embryos with Cas9 protein and a single-guide RNA targeting exon 23 of DMD. The DMD-edited microminipigs exhibited pronounced clinical phenotypes, including perturbed locomotion and body-wide skeletal muscle weakness and atrophy, alongside augmented serum creatine kinase levels. Muscle weakness was observed as of one month of age, respiratory and cardiac dysfunctions emerged by the sixth month, and the maximum lifespan was 29.9 months. Histopathological evaluations confirmed dystrophin deficiency and pronounced dystrophic pathology in the skeletal and myocardial tissues, demonstrating that these animals are an unprecedented model for studying human DMD. The model stands as a distinct and crucial tool in biomedical research, offering deep understanding of disease progression and enhancing therapeutic assessments, with potential to influence forthcoming treatment approaches.
Topics: Muscular Dystrophy, Duchenne; Animals; Swine, Miniature; Disease Models, Animal; Swine; Muscle, Skeletal; Dystrophin; Gene Editing; Humans; Male; Phenotype
PubMed: 38702481
DOI: 10.1038/s42003-024-06222-5 -
Annals of Clinical and Translational... Jun 2024Duchenne and Becker muscular dystrophies (DMD and BMD) are dystrophinopathies caused by variants in DMD gene, resulting in reduced or absent dystrophin. These...
OBJECTIVE
Duchenne and Becker muscular dystrophies (DMD and BMD) are dystrophinopathies caused by variants in DMD gene, resulting in reduced or absent dystrophin. These conditions, characterized by muscle weakness, also manifest central nervous system (CNS) comorbidities due to dystrophin expression in the CNS. Prior studies have indicated a higher prevalence of epilepsy in individuals with dystrophinopathy compared to the general population. Our research aimed to investigate epilepsy prevalence in dystrophinopathies and characterize associated electroencephalograms (EEGs) and seizures.
METHODS
We reviewed 416 individuals with dystrophinopathy, followed up at three centers between 2010 and 2023, to investigate the lifetime epilepsy prevalence and characterize EEGs and seizures in those individuals diagnosed with epilepsy. Associations between epilepsy and type of dystrophinopathy, genotype, and cognitive involvement were studied.
RESULTS
Our study revealed a higher epilepsy prevalence than the general population (1.4%; 95% confidence interval: 0.7-3.2%), but notably lower than previously reported in smaller dystrophinopathy cohorts. No significant differences were found in epilepsy prevalence between DMD and BMD or based on underlying genotypes. Cognitive impairment was not found to be linked to higher epilepsy rates. The most prevalent epilepsy types in dystrophinopathies resembled those observed in the broader pediatric population, with most individuals effectively controlled through monotherapy.
INTERPRETATION
The actual epilepsy prevalence in dystrophinopathies may be markedly lower than previously estimated, possibly half or even less. Our study provides valuable insights into the epilepsy landscape in individuals with dystrophinopathy, impacting medical care, especially for those with concurrent epilepsy.
Topics: Humans; Muscular Dystrophy, Duchenne; Male; Epilepsy; Adolescent; Female; Adult; Young Adult; Child; Prevalence; Middle Aged; Child, Preschool; Electroencephalography; Comorbidity; Dystrophin
PubMed: 38693632
DOI: 10.1002/acn3.52058 -
JAMA May 2024
Topics: Humans; Drug Approval; Dystrophin; Genetic Therapy; Muscular Dystrophy, Duchenne; United States; United States Food and Drug Administration; Male; Child, Preschool; Child; Clinical Trials as Topic
PubMed: 38691382
DOI: 10.1001/jama.2024.5613