Journal of Neuromuscular Diseases - Volume 8, issue s2

Authors: Jaiswal, Jyoti K. | Nagaraju, Kanneboyina | Morgan, Jennifer

Article Type: Editorial

DOI: 10.3233/JND-219010

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S173-S179, 2021

Article Type: Other

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S181-S181, 2021

Authors: Engquist, Elise N. | Zammit, Peter S.

Article Type: Review Article

Abstract: The resident stem cell for skeletal muscle is the satellite cell. On the 50th anniversary of its discovery in 1961, we described the history of skeletal muscle research and the seminal findings made during the first 20 years in the life of the satellite cell (Scharner and Zammit 2011, doi: 10.1186/2044-5040-1-28). These studies established the satellite cell as the source of myoblasts for growth and regeneration of skeletal muscle. Now on the 60th anniversary, we highlight breakthroughs in the second phase of satellite cell research from 1980 to 2000. These include technical innovations such as isolation of primary satellite cells …and viable muscle fibres complete with satellite cells in their niche, together with generation of many useful reagents including genetically modified organisms and antibodies still in use today. New methodologies were combined with description of endogenous satellite cells markers, notably Pax7. Discovery of the muscle regulatory factors Myf5, MyoD, myogenin, and MRF4 in the late 1980s revolutionized understanding of the control of both developmental and regerenative myogenesis. Emergence of genetic lineage markers facilitated identification of satellite cells in situ , and also empowered transplantation studies to examine satellite cell function. Finally, satellite cell heterogeneity and the supportive role of non-satellite cell types in muscle regeneration were described. These major advances in methodology and in understanding satellite cell biology provided further foundations for the dramatic escalation of work on muscle stem cells in the 21st century. Show more

Keywords: Satellite cell, skeletal muscle, muscle regulatory factors, muscle regeneration, myofibre, Pax7, MyoD, Myf5

DOI: 10.3233/JND-210705

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S183-S203, 2021

Authors: Goswami, Mansi V. | Tawalbeh, Shefa M. | Canessa, Emily H. | Hathout, Yetrib

Article Type: Research Article

Abstract: Background: Myogenesis is a dynamic process involving temporal changes in the expression of many genes. Lack of dystrophin protein such as in Duchenne muscular dystrophy might alter the natural course of gene expression dynamics during myogenesis. Objective: To gain insight into the dynamic temporal changes in protein expression during differentiation of normal and dystrophin deficient myoblasts to myotubes. Method: A super SILAC spike-in strategy in combination and LC-MS/MS was used for temporal proteome profiling of normal and dystrophin deficient myoblasts during differentiation. The acquired data was analyzed using Proteome Discoverer 2.2. and data clustering using R …to define significant temporal changes in protein expression. Results: sFour major temporal protein clusters that showed sequential dynamic expression profiles during myogenesis of normal myoblasts were identified. Clusters 1 and 2, consisting mainly of proteins involved mRNA splicing and processing expression, were elevated at days 0 and 0.5 of differentiation then gradually decreased by day 7 of differentiation, then remained lower thereafter. Cluster 3 consisted of proteins involved contractile muscle and actomyosin organization. They increased in their expression reaching maximum at day 7 of differentiation then stabilized thereafter. Cluster 4 consisting of proteins involved in skeletal muscle development glucogenesis and extracellular remodeling had a lower expression during myoblast stage then gradually increased in their expression to reach a maximum at days 11–15 of differentiation. Lack of dystrophin expression in DMD muscle myoblast caused major alteration in temporal expression of proteins involved in cell adhesion, cytoskeleton, and organelle organization as well as the ubiquitination machinery. Conclusion: Time series proteome profiling using super SILAC strategy is a powerful method to assess temporal changes in protein expression during myogenesis and to define the downstream consequences of lack of dystrophin on these temporal protein expressions. Key alterations were identified in dystrophin deficient myoblast differentiation compared to normal myoblasts. These alterations could be an attractive therapeutic target. Show more

Keywords: Mass spectrometry, SILAC, proteome profiling, myoblasts, myotubes, myogenesis, mass, Dystrophin, Duchenne muscular dystrophy

DOI: 10.3233/JND-210713

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S205-S222, 2021

Authors: Morgan, Stephen | Malatras, Apostolos | Duguez, Stephanie | Duddy, William

Article Type: Research Article

Abstract: Background: Molecular interaction networks (MINs) aim to capture the complex relationships between interacting molecules within a biological system. MINs can be constructed from existing knowledge of molecular functional associations, such as protein-protein binding interactions (PPI) or gene co-expression, and these different sources may be combined into a single MIN. A given MIN may be more or less optimal in its representation of the important functional relationships of molecules in a tissue. Objective: The aim of this study was to establish whether a combined MIN derived from different types of functional association could better capture muscle-relevant biology compared to …its constituent single-source MINs. Methods: MINs were constructed from functional association databases for both protein-binding and gene co-expression. The networks were then compared based on the capture of muscle-relevant genes and gene ontology (GO) terms, tested in two different ways using established biological network clustering algorithms. The top performing MINs were combined to test whether an optimal MIN for skeletal muscle could be constructed. Results: The STRING PPI network was the best performing single-source MIN among those tested. Combining STRING with interactions from either the MyoMiner or CoXPRESSdb gene co-expression sources resulted in a combined network with improved performance relative to its constituent networks. Conclusion: MINs constructed from multiple types of functional association can better represent the functional relationships of molecules in a given tissue. Such networks may be used to improve the analysis and interpretation of functional genomics data in the study of skeletal muscle and neuromuscular diseases. Networks and clusters described by this study, including the combinations of STRING with MyoMiner or with CoXPRESSdb, are available for download from https://www.sys-myo.com/myominer/download.php . Show more

Keywords: Skeletal muscle, neuromuscular disease, molecular interaction networks, network medicine, functional genomics, protein-protein interactions, gene co-expression

DOI: 10.3233/JND-210680

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S223-S239, 2021

Article Type: Other

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S241-S241, 2021

Authors: Thiruvengadam, Girija | Sreetama, Sen Chandra | Charton, Karine | Hogarth, Marshall | Novak, James S. | Suel-Petat, Laurence | Chandra, Goutam | Allard, Bruno | Richard, Isabelle | Jaiswal, Jyoti K.

Article Type: Research Article

Abstract: Mutations in the Anoctamin 5 (Ano5 ) gene that result in the lack of expression or function of ANO5 protein, cause Limb Girdle Muscular Dystrophy (LGMD) 2L/R12, and Miyoshi Muscular Dystrophy (MMD3). However, the dystrophic phenotype observed in patient muscles is not uniformly recapitulated by ANO5 knockout in animal models of LGMD2L. Here we describe the generation of a mouse model of LGMD2L generated by targeted out-of-frame deletion of the Ano5 gene. This model shows progressive muscle loss, increased muscle weakness, and persistent bouts of myofiber regeneration without chronic muscle inflammation, which recapitulates the mild to moderate skeletal muscle …dystrophy reported in the LGMD2L patients. We show that these features of ANO5 deficient muscle are not associated with a change in the calcium-activated sarcolemmal chloride channel activity or compromised in vivo regenerative myogenesis. Use of this mouse model allows conducting in vivo investigations into the functional role of ANO5 in muscle health and for preclinical therapeutic development for LGMD2L. Show more

Keywords: Anoctamin, TMEM16, ion channel, muscle, Muscular Dystrophy, LGMDR12, scramblase, myogenesis

DOI: 10.3233/JND-210720

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S243-S255, 2021

Authors: Partridge, Terence A.

Article Type: Review Article

Abstract: Careful quantitative analysis of histological preparations of muscle samples is crucial to accurate investigation of myopathies in man and of interpretation of data from animals subjected to experimental or potentially therapeutic treatments. Protocols for measuring cell numbers are subject to problems arising from biases associated with preparative and analytical techniques. Prominent among these is the effect of polarized structure of skeletal muscle on sampling bias. It is also common in this tissue to collect data as ratios to convenient reference dominators, the fundamental bases of which are ill-defined, or unrecognized or not accurately assessable. Use of such ‘floating’ denominators raises …a barrier to estimation of the absolute values that assume practical importance in medical research, where accurate comparison between different scenarios in different species is essential to the aim of translating preclinical research findings in animal models to clinical utility in Homo sapiens. This review identifies some of the underappreciated problems with current morphometric practice, some of which are exacerbated in skeletal muscle, and evaluates the extent of their intrusiveness into the of building an objective, accurate, picture of the structure of the muscle sample. It also contains recommendations for eliminating or at least minimizing these problems. Principal among these, would be the use of stereological procedures to avoid the substantial counting biases arising from inter-procedure differences in object size and section thickness. Attention is also drawn to the distortions of interpretation arising from use of undefined or inappropriate denominators. Show more

Keywords: Muscle histology, quantitative morphometry, procedural bias, denominator bias, phenomenology

DOI: 10.3233/JND-210736

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S257-S269, 2021

Authors: Phelps, Michael | Yablonka-Reuveni, Zipora

Article Type: Research Article

Abstract: Background: Duchenne muscular dystrophy is a degenerative muscle disease that results from impairment of the dystrophin gene. The disease causes progressive loss in muscle mass and function. Objective: The anti-aging protein, α-klotho, has been implicated in the regulation of muscle regeneration. We previously discovered that mice harboring reduced α-klotho levels exhibited a decline in muscle strength and running endurance. Method: To investigate the ability of α-klotho to improve overall endurance in a dystrophin null murine model, we examined the voluntary wheel running performance of dystrophin-null, mdx4cv mice overexpressing an α-klotho transgene. Results: As …expected, compared to wild type, both male and female dystrophic mice exhibited reduced running ability that was characterized by shorter running duration and longer periods of rest between cycles of activity. While our results did not detect an improvement in running performance with α-klotho overexpression, we identified distinct differences in the running patterns between females and males from all mouse strains analyzed (i.e., mdx4cv , mdx4cv overexpressing α-klotho, α-klotho overexpressing, α-klotho hypomorph, and wild type). For all strains, male mice displayed significantly reduced voluntary running ability compared to females. Further analysis of the mdx4cv strains demonstrated that male mice ran for shorter lengths of time and took longer breaks. However, we did not identify gender-associated differences in the actual speed at which mdx4cv mice ran. Conclusion: Our data suggest key differences in the running capabilities of female and male mice, which are of particular relevance to studies of dystrophin-null mice. Show more

Keywords: Running wheel, mdx, mdx4cv, α-klotho

DOI: 10.3233/JND-210703

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S271-S281, 2021

Authors: Deres, Friederike | Schwartz, Stephanie | Kappes-Horn, Karin | Kornblum, Cornelia | Reimann, Jens

Article Type: Research Article

Abstract: Background: The C22 mouse is a Charcot-Marie-Tooth 1A transgenic model with minimal axonal loss. Objective: To analyse early skeletal muscle changes resulting from this dysmyelinating neuropathy. Methods: Histology of tibialis anterior muscles of C22 mice and wild type litter mate controls for morphometric analysis and (immuno-)histochemistry for known denervation markers and candidate proteins identified by representational difference analysis (RDA) based on mRNA from the same muscles; quantitative PCR and Western blotting for confirmation of RDA findings. Results: At age 10 days, morphometry was not different between groups, while at 21 days, C22 showed significantly …more small diameter fibres, indicating the onset of atrophy at an age when weakness becomes detectable. Neither (immuno-)histochemistry nor RDA detected extrajunctional expression of acetylcholine receptors by age 10 and 21 days, respectively. RDA identified some mRNA up-regulated in C22 muscles, among them at 10 days, prior to detectable weakness or atrophy, integral membrane protein 2a (Itm2a ), eukaryotic initiation factor 2, subunit 2 (Eif2s2 ) and cytoplasmic phosphatidylinositol transfer protein 1 (Pitpnc1 ). However, qPCR failed to measure significant differences. In contrast, Itm2a and Eif2s2 mRNA were significantly down-regulated comparing 21 versus 10 days of age in both groups, C22 and controls. Western blotting confirmed significant down-regulation of ITM2A protein in C22 only. Conclusion: Denervation-like changes in this model develop slowly with onset of atrophy and weakness at about three weeks of age, before detection of extrajunctional acetylcholine receptors. Altered Itm2a expression seems to begin early as an increase, but becomes distinct as a decrease later. Show more

Keywords: Skeletal muscle, muscle denervation, charcot-marie-tooth disease, demyelination, gene expression profiling, integral membrane protein 2A, eukaryotic initiation factor 2, beta subunit, phosphatidylinositol transfer protein, cytoplasmic 1

DOI: 10.3233/JND-210681

Citation: Journal of Neuromuscular Diseases, vol. 8, no. s2, pp. S283-S299, 2021