Amphiphysin 2 modulation rescues myotubular myopathy and prevents focal adhesion defects in mice

Centronuclear myopathies (CNMs) are severe diseases characterized by muscle weakness and myofiber atrophy. Currently, there are no approved treatments for these disorders. Mutations in the phosphoinositide 3-phosphatase myotubularin (MTM1) are responsible for X-linked CNM (XLCNM), also called myotubular myopathy, whereas mutations in the membrane remodeling Bin/amphiphysin/Rvs protein amphiphysin 2 [bridging integrator 1 (BIN1)] are responsible for an autosomal form of the disease. Here, we investigated the functional relationship between MTM1 and BIN1 in healthy skeletal muscle and in the physiopathology of CNM. Genetic overexpression of human BIN1 efficiently rescued the muscle weakness and life span in a mouse model of XLCNM. Exogenous human BIN1 expression with adeno-associated virus after birth also prevented the progression of the disease, suggesting that human BIN1 overexpression can compensate for the lack of MTM1 expression in this mouse model. Our results showed that MTM1 controls cell adhesion and integrin localization in mammalian muscle. Alterations in this pathway in Mtm1−/y mice were associated with defects in myofiber shape and size. BIN1 expression rescued integrin and laminin alterations and restored myofiber integrity, supporting the idea that MTM1 and BIN1 are functionally linked and necessary for focal adhesions in skeletal muscle. The results suggest that BIN1 modulation might be an effective strategy for treating XLCNM.

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RPS6 phosphorylation occurs to a greater extent in the periphery of human skeletal muscle fibers, near focal adhesions, after anabolic stimuli

AJP Cell Physiology ◽

10.1152/ajpcell.00357.2021 ◽

2021 ◽

Author(s):

Nathan Hodson ◽

Michael Mazzulla ◽

Maksym N. H. Holowaty ◽

Dinesh Kumbhare ◽

Daniel R. Moore

Keyword(s):

Skeletal Muscle ◽

Focal Adhesion ◽

Human Skeletal Muscle ◽

Muscle Fibers ◽

Focal Adhesions ◽

Immunofluorescent Staining ◽

Whole Body ◽

Vastus Lateralis Muscle ◽

Cell Periphery ◽

Rps6 Phosphorylation

Following anabolic stimuli (mechanical loading and/or amino acid provision) the mechanistic target of rapamycin complex 1 (mTORC1), a master regulator of protein synthesis, translocates toward the cell periphery. However, it is unknown if mTORC1-mediated phosphorylation events occur in these peripheral regions or prior to translocation (i.e. in central regions). We therefore aimed to determine the cellular location of a mTORC1-mediated phosphorylation event, RPS6Ser240/244, in human skeletal muscle following anabolic stimuli. Fourteen young, healthy males either ingested a protein-carbohydrate beverage (0.25g/kg protein, 0.75g/kg carbohydrate) alone (n=7;23±5yrs;76.8±3.6kg;13.6±3.8%BF, FED) or following a whole-body resistance exercise bout (n=7;22±2yrs;78.1±3.6kg;12.2±4.9%BF, EXFED). Vastus lateralis muscle biopsies were obtained at rest (PRE) and 120 and 300min following anabolic stimuli. RPS6Ser240/244 phosphorylation measured by immunofluorescent staining or immunoblot was positively correlated (r=0.76, p<0.001). Peripheral staining intensity of p-RPS6Ser240/244 increased above PRE in both FED and EXFED at 120min (~54% and ~138% respectively, p<0.05) but was greater in EXFED at both post-stimuli time points (p<0.05). The peripheral-central ratio of p-RPS6240/244 staining displayed a similar pattern, even when corrected for total RPS6 distribution, suggesting RPS6 phosphorylation occurs to a greater extent in the periphery of fibers. Moreover, p-RPS6Ser240/244 intensity within paxillin-positive regions, a marker of focal adhesion complexes, was elevated at 120min irrespective of stimulus (p=0.006) before returning to PRE at 300min. These data confirm that RPS6Ser240/244 phosphorylation occurs in the region of human muscle fibers to which mTOR translocates following anabolic stimuli and identifies focal adhesion complexes as a potential site of mTORC1 regulation in vivo.

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Osteolytic Breast Cancer Causes Skeletal Muscle Weakness in an Immunocompetent Syngeneic Mouse Model

Frontiers in Endocrinology ◽

10.3389/fendo.2017.00358 ◽

2017 ◽

Vol 8 ◽

Cited By ~ 9

Author(s):

Jenna N. Regan ◽

Carter Mikesell ◽

Steven Reiken ◽

Haifang Xu ◽

Andrew R. Marks ◽

...

Keyword(s):

Breast Cancer ◽

Skeletal Muscle ◽

Mouse Model ◽

Muscle Weakness ◽

Syngeneic Mouse ◽

Syngeneic Mouse Model ◽

Skeletal Muscle Weakness

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A motor axonopathy in a mouse model of Duchenne Muscular Dystrophy

10.1101/2020.01.22.914614 ◽

2020 ◽

Author(s):

Justin S. Dhindsa ◽

Angela L. McCall ◽

Laura M. Strickland ◽

Anna F. Fusco ◽

Amanda F. Kahn ◽

...

Keyword(s):

Skeletal Muscle ◽

Respiratory Failure ◽

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Mouse Model ◽

Cause Of Death ◽

Muscle Weakness ◽

Common Cause ◽

Skeletal Muscle Weakness ◽

Nerve Dysfunction

AbstractSkeletal muscle weakness due to loss of dystrophin is a well-documented pathological hallmark of Duchenne muscular dystrophy (DMD). In contrast, the neuropathology of this disease remains understudied. Here, we characterize an axonopathy in the phrenic and hypoglossal (XII) nerves of mdx mice. We observe nerve dysfunction that we propose contributes to respiratory failure, the most common cause of death in DMD.

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Metabolic and functional characterization of adult skeletal muscle in Down syndrome mouse model (Ts1Cje): insight into the muscle weakness (hypotonia) seen in the human condition.

Frontiers in Cellular Neuroscience ◽

10.3389/conf.fncel.2016.36.00193 ◽

2016 ◽

Vol 10 ◽

Author(s):

Lim Chai ◽

Ramasamy Rajesh ◽

Stanslas Johnson ◽

Ling King ◽

Cheah Pike

Keyword(s):

Skeletal Muscle ◽

Down Syndrome ◽

Mouse Model ◽

Muscle Weakness ◽

Functional Characterization ◽

Human Condition ◽

Adult Skeletal Muscle ◽

Insight Into ◽

The Human Condition

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Dexamethasone accelerates muscle regeneration by modulating kinesin-1-mediated focal adhesion signals

Cell Death Discovery ◽

10.1038/s41420-021-00412-4 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Jong-Wei Lin ◽

Yi-Man Huang ◽

Yin-Quan Chen ◽

Ting-Yun Chuang ◽

Tien-Yun Lan ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscular Dystrophy ◽

Motor Activity ◽

Focal Adhesion ◽

Muscle Regeneration ◽

Focal Adhesions ◽

Myoblast Fusion ◽

Skeletal Muscle Regeneration ◽

Integrin Β1 ◽

Muscle Myosin

AbstractDuring differentiation, skeletal muscle develops mature multinucleated muscle fibers, which could contract to exert force on a substrate. Muscle dysfunction occurs progressively in patients with muscular dystrophy, leading to a loss of the ability to walk and eventually to death. The synthetic glucocorticoid dexamethasone (Dex) has been used therapeutically to treat muscular dystrophy by an inhibition of inflammation, followed by slowing muscle degeneration and stabilizing muscle strength. Here, in mice with muscle injury, we found that Dex significantly promotes muscle regeneration via promoting kinesin-1 motor activity. Nevertheless, how Dex promotes myogenesis through kinesin-1 motors remains unclear. We found that Dex directly increases kinesin-1 motor activity, which is required for the expression of a myogenic marker (muscle myosin heavy chain 1/2), and also for the process of myoblast fusion and the formation of polarized myotubes. Upon differentiation, kinesin-1 mediates the recruitment of integrin β1 onto microtubules allowing delivery of the protein into focal adhesions. Integrin β1-mediated focal adhesion signaling then guides myoblast fusion towards a polarized morphology. By imposing geometric constrains via micropatterns, we have proved that cell adhesion is able to rescue the defects caused by kinesin-1 inhibition during the process of myogenesis. These discoveries reveal a mechanism by which Dex is able to promote myogenesis, and lead us towards approaches that are more efficient in improving skeletal muscle regeneration.

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Transgenic mice expressing tunable levels of DUX4 develop characteristic facioscapulohumeral muscular dystrophy-like pathophysiology ranging in severity

10.1101/471094 ◽

2018 ◽

Cited By ~ 1

Author(s):

Takako I. Jones ◽

Guo-Liang Chew ◽

Pamela Barraza-Flores ◽

Spencer Schreier ◽

Monique Ramirez ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscular Dystrophy ◽

Mouse Model ◽

Transgenic Mice ◽

Transgenic Mouse ◽

Muscle Weakness ◽

Facioscapulohumeral Muscular Dystrophy ◽

Transgenic Mouse Model ◽

Large Variability ◽

Low Level

AbstractBackgroundAll types of facioscapulohumeral muscular dystrophy (FSHD) are caused by the aberrant myogenic activation of the somatically silent DUX4 gene, which initiates a cascade of cellular events ultimately leading to FSHD pathophysiology. Therefore, FSHD is a dominant gain-of-function disease that is amenable to modeling by DUX4 overexpression. However, there is large variability in the patient population. Typically, progressive skeletal muscle weakness becomes noticeable in the second or third decade of life, yet there are many genetically FSHD individuals who develop symptoms much later in life or remain relatively asymptomatic throughout their lives. Conversely, in rare cases, FSHD may present clinically prior to 5-10 yrs of age, ultimately manifesting as a very severe early onset form of the disease. Thus, there is a need to control the timing and severity of pathology in FSHD-like models.MethodsWe have recently described a line of conditional DUX4 transgenic mice, FLExDUX4, that develop a myopathy upon induction of human DUX4-fl expression in skeletal muscle. Here, we use the FLExDUX4 mouse crossed with the skeletal muscle-specific and tamoxifen inducible line ACTAl-MerCreMer to generate a highly versatile bi-transgenic mouse model with chronic, low-level DUX4-fl expression and mild pathology, that can be induced to develop more severe FSHD-like pathology in a dose-dependent response to tamoxifen. We identified conditions to reproducibly generate models exhibiting mild, moderate, or severe DUX4-dependent pathophysiology, and characterized their progression.ResultsWe assayed DUX4-fl mRNA and protein levels, fitness, strength, global gene expression, histopathology, and immune response, all of which are consistent with an FSHD-like myopathic phenotype. Importantly, we identified sex-specific and muscle-specific differences that should be considered when using these models for preclinical studies.ConclusionsThe ACTA1-MCM;FLExDUX4 bi-transgenic mouse model expresses a chronic low level of DUX4-fl and has mild pathology and detectable muscle weakness. The onset and progression of moderate to severe pathology can be controlled via tamoxifen injection to provide consistent and readily screenable phenotypes for assessing therapies targeting DUX4-fl mRNA and protein. Thus, these FSHD-like mouse models can be used to study a range of DUX4-fl expression and pathology dependent upon investigator need, through controlled mosaic expression of DUX4.

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Faculty Opinions recommendation of The molecular basis of skeletal muscle weakness in a mouse model of inflammatory myopathy.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717961882.793464577 ◽

2012 ◽

Author(s):

Jiri Vencovsky ◽

Herman Mann

Keyword(s):

Skeletal Muscle ◽

Mouse Model ◽

Muscle Weakness ◽

Molecular Basis ◽

Inflammatory Myopathy ◽

Skeletal Muscle Weakness

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Transcriptomic profiling of skeletal muscle from the Ts1Cje mouse model of Down syndrome suggests dysregulation of trisomic genes associated with neuromuscular junction signaling, oxidative stress and chronic inflammation

Neuroscience Research Notes ◽

10.31117/neuroscirn.v1i1.12 ◽

2018 ◽

Vol 1 (1) ◽

pp. 21-41 ◽

Cited By ~ 1

Author(s):

Melody Pui Yee Leong ◽

Usman Bala ◽

Chai Ling Lim ◽

Rozita Rosli ◽

Pike-See Cheah ◽

...

Keyword(s):

Oxidative Stress ◽

Gene Expression ◽

Skeletal Muscle ◽

Down Syndrome ◽

Neuromuscular Junction ◽

Mouse Model ◽

Chronic Inflammation ◽

Muscle Weakness ◽

Protein Modification ◽

Chromosome 21

Ts1Cje is a mouse model of Down syndrome (DS) with partial triplication of chromosome 16, which encompasses a high number of human chromosome 21 (HSA21) orthologous genes. The mouse model exhibits muscle weakness resembling hypotonia in DS individuals. The effect of extra gene dosages on muscle weakness or hypotonia in Ts1Cje and DS individuals remains unknown. To identify molecular dysregulation of the skeletal muscle, we compared the transcriptomic signatures of soleus and extensor digitorum longus (EDL) muscles between the adult Ts1Cje and disomic littermates. A total of 166 and 262 differentially expressed protein-coding genes (DEGs) were identified in the soleus and EDL muscles, respectively. The partial trisomy of MMU16 in Ts1Cje mice has a greater effect on gene expression in EDL. Top-down clustering analysis of all DEGs for represented functional ontologies revealed 5 functional clusters in soleus associated with signal transduction, development of reproductive system, nucleic acid biosynthesis, protein modification and metabolism as well as regulation of gene expression. On the other hand, only 3 functional clusters were observed for EDL namely neuron and cell development, protein modification and metabolic processes as well as ion transport. A total of 11 selected DEGs were validated using qPCR (disomic DEGs: Mansc1; trisomic DEGs: Itsn1, Rcan1, Synj1, Donson, Dyrk1a, Ifnar1, Ifnar2, Runx1, Sod1 and Tmem50b). The validated DEGs were implicated in neuromuscular junction signalling (Itsn1, Syn1), oxidative stress (Sod1, Runx1) and chronic inflammation processes (Runx1, Rcan1, Ifnar1, Ifnar2). Other validated DEGs have not been well-documented as involved in the skeletal muscle development or function, thus serve as interesting novel candidates for future investigations. To our knowledge, the study was the first attempt to determine the transcriptomic profiles of both soleus and EDL muscles in Ts1Cje mice. It provides new insights on the possible disrupted molecular pathways associated with hypotonia in DS individuals.

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Impaired aerobic capacity and premature fatigue preceding muscle weakness in the skeletal muscle Tfam KO mouse model

Disease Models & Mechanisms ◽

10.1242/dmm.048981 ◽

2021 ◽

Author(s):

Benjamin Chatel ◽

Sylvie Ducreux ◽

Zeina Harhous ◽

Nadia Bendridi ◽

Isabelle Varlet ◽

...

Keyword(s):

Skeletal Muscle ◽

Mouse Model ◽

Muscle Weakness ◽

Time Course ◽

Genetic Disorders ◽

Mitochondrial Diseases ◽

Early Death ◽

Exercise Intolerance ◽

Time Course Study ◽

Respiratory Chain Activity

Mitochondrial diseases are genetic disorders leading to an impaired mitochondrial function and resulting in exercise intolerance and muscle weakness. In patients, muscle fatigue due to defects in mitochondrial oxidative capacities commonly precedes muscle weakness. In mice, the fast-twitch skeletal muscle-specific Tfam deletion (Tfam KO) leads to deficit in the respiratory chain activity, severe muscle weakness and early death. Here, we performed a time-course study of mitochondrial and muscular dysfunctions in 11 and 14 weeks Tfam KO mice, i.e., before and when mice are about to enter the terminal stage, respectively. While force in the unfatigued state was reduced in Tfam KO mice as compared to control littermates (WT) only at 14 weeks, during repeated submaximal contractions fatigue was faster at both ages. During fatiguing stimulation, total phosphocreatine breakdown was larger in Tfam KO muscle than in WT muscle at both ages whereas phosphocreatine consumption was faster only at 14 weeks. In conclusion, the Tfam KO mouse model represents a reliable model of lethal mitochondrial myopathy where impaired mitochondrial energy production and premature fatigue occur before muscle weakness and early death.

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