scholarly journals Ultrastructural immunocytochemistry shows impairment of RNA pathways in skeletal muscle nuclei of old mice: A link to sarcopenia?

2021 ◽  
Vol 65 (2) ◽  
Author(s):  
Maria Assunta Lacavalla ◽  
Barbara Cisterna ◽  
Carlo Zancanaro ◽  
Manuela Malatesta
Keyword(s):  
Skeletal Muscle ◽  
Ribonuclease A ◽  
Rrna Genes ◽  
Nuclear Actin ◽  
Ultrastructural Immunocytochemistry ◽  
Nuclear Compartments ◽  
Age Related ◽  
Methyl Cytosine ◽  
Rna Pathways ◽  
Old Mice

During aging, skeletal muscle is affected by sarcopenia, a progressive decline in muscle mass, strength and endurance that leads to loss of function and disability. Cell nucleus dysfunction is a possible factor contributing to sarcopenia because aging-associated alterations in mRNA and rRNA transcription/maturation machinery have been shown in several cell types including muscle cells. In this study, the distribution and density of key molecular factors involved in RNA pathways namely, nuclear actin (a motor protein and regulator of RNA transcription), 5-methyl cytosine (an epigenetic regulator of gene transcription), and ribonuclease A (an RNA degrading enzyme) were compared in different nuclear compartments of late adult and old mice myonuclei by means of ultrastructural immunocytochemistry. In all nuclear compartments, an age-related decrease of nuclear actin suggested altered chromatin structuring and impaired nucleus-to-cytoplasm transport of both mRNA and ribosomal subunits, while a decrease of 5-methyl cytosine and ribonuclease A in the nucleoli of old mice indicated an age-dependent loss of rRNA genes. These findings provide novel experimental evidence that, in the aging skeletal muscle, nuclear RNA pathways undergo impairment, likely hindering protein synthesis and contributing to the onset and progression of sarcopenia.

scholarly journals Inflamma-miR-21 Negatively Regulates Myogenesis during Ageing

Antioxidants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 345 ◽  
Author(s):  
Maria Borja-Gonzalez ◽  
Jose C. Casas-Martinez ◽  
Brian McDonagh ◽  
Katarzyna Goljanek-Whysall
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cells ◽  
Muscle Regeneration ◽  
Muscle Hypertrophy ◽  
Myogenic Potential ◽  
Age Related ◽  
Primary Myoblasts ◽  
Muscle Homeostasis ◽  
Old Mice

Ageing is associated with disrupted redox signalling and increased circulating inflammatory cytokines. Skeletal muscle homeostasis depends on the balance between muscle hypertrophy, atrophy and regeneration, however during ageing this balance is disrupted. The molecular pathways underlying the age-related decline in muscle regenerative potential remain elusive. microRNAs are conserved robust gene expression regulators in all tissues including skeletal muscle. Here, we studied satellite cells from adult and old mice to demonstrate that inhibition of miR-21 in satellite cells from old mice improves myogenesis. We determined that increased levels of proinflammatory cytokines, TNFα and IL6, as well as H2O2, increased miR-21 expression in primary myoblasts, which in turn resulted in their decreased viability and myogenic potential. Inhibition of miR-21 function rescued the decreased size of myotubes following TNFα or IL6 treatment. Moreover, we demonstrated that miR-21 could inhibit myogenesis in vitro via regulating IL6R, PTEN and FOXO3 signalling. In summary, upregulation of miR-21 in satellite cells and muscle during ageing may occur in response to elevated levels of TNFα and IL6, within satellite cells or myofibrillar environment contributing to skeletal muscle ageing and potentially a disease-related decline in potential for muscle regeneration.

scholarly journals The NLRP3 inflammasome contributes to sarcopenia and lower muscle glycolytic potential in old mice

2017 ◽  
Vol 313 (2) ◽  
pp. E222-E232 ◽  
Author(s):  
Marin Jane McBride ◽  
Kevin P. Foley ◽  
Donna M. D’Souza ◽  
Yujin E. Li ◽  
Trevor C. Lau ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Strength ◽  
Nlrp3 Inflammasome ◽  
Skeletal Muscles ◽  
Metabolic Flux ◽  
Caspase 1 ◽  
Gapdh Activity ◽  
Age Related ◽  
Glycolytic Potential ◽  
Old Mice

The mechanisms underpinning decreased skeletal muscle strength and slowing of movement during aging are ill-defined. “Inflammaging,” increased inflammation with advancing age, may contribute to aspects of sarcopenia, but little is known about the participatory immune components. We discovered that aging was associated with increased caspase-1 activity in mouse skeletal muscle. We hypothesized that the caspase-1-containing NLRP3 inflammasome contributes to sarcopenia in mice. Male C57BL/6J wild-type (WT) and NLRP3−/− mice were aged to 10 (adult) and 24 mo (old). NLRP3−/− mice were protected from decreased muscle mass (relative to body mass) and decreased size of type IIB and IIA myofibers, which occurred between 10 and 24 mo of age in WT mice. Old NLRP3−/− mice also had increased relative muscle strength and endurance and were protected from age-related increases in the number of myopathic fibers. We found no evidence of age-related or NLRP3-dependent changes in markers of systemic inflammation. Increased caspase-1 activity was associated with GAPDH proteolysis and reduced GAPDH enzymatic activity in skeletal muscles from old WT mice. Aging did not alter caspase-1 activity, GAPDH proteolysis, or GAPDH activity in skeletal muscles of NLRP3−/− mice. Our results show that the NLRP3 inflammasome participates in age-related loss of muscle glycolytic potential. Deletion of NLRP3 mitigates both the decline in glycolytic myofiber size and the reduced activity of glycolytic enzymes in muscle during aging. We propose that the etiology of sarcopenia involves direct communication between immune responses and metabolic flux in skeletal muscle.

scholarly journals FTIR Spectroscopy as a Tool to Study Age-Related Changes in Cardiac and Skeletal Muscle of Female C57BL/6J Mice

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6410
Author(s):  
Sandra Magalhães ◽  
Idália Almeida ◽  
Filipa Martins ◽  
Fátima Camões ◽  
Ana R. Soares ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ftir Spectroscopy ◽  
Conformational Changes ◽  
Molecular Mechanisms ◽  
Protein Secondary Structure ◽  
Multivariate Statistical ◽  
Age Related ◽  
Muscle Tissues ◽  
Aging Studies ◽  
Old Mice

Studying aging is important to further understand the molecular mechanisms underlying this physiological process and, ideally, to identify a panel of aging biomarkers. Animals, in particular mice, are often used in aging studies, since they mimic important features of human aging, age quickly, and are easy to manipulate. The present work describes the use of Fourier Transform Infrared (FTIR) spectroscopy to identify an age-related spectroscopic profile of the cardiac and skeletal muscle tissues of C57BL/6J female mice. We acquired ATR-FTIR spectra of cardiac and skeletal muscle at four different ages: 6; 12; 17 and 24 months (10 samples at each age) and analyzed the data using multivariate statistical tools (PCA and PLS) and peak intensity analyses. The results suggest deep changes in protein secondary structure in 24-month-old mice compared to both tissues in 6-month-old mice. Oligomeric structures decreased with age in both tissues, while intermolecular β-sheet structures increased with aging in cardiac muscle but not in skeletal muscle. Despite FTIR spectroscopy being unable to identify the proteins responsible for these conformational changes, this study gives insights into the potential of FTIR to monitor the aging process and identify an age-specific spectroscopic signature.

scholarly journals High Resolution Genome Wide Expression Analysis of Single Myofibers Using SMART-Seq

2019 ◽  
Author(s):  
Darren M. Blackburn ◽  
Felicia Lazure ◽  
Aldo H. Corchado ◽  
Theodore J. Perkins ◽  
Hamed S. Najafabadi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
High Resolution ◽  
Expression Analysis ◽  
Expression Profiles ◽  
Age Related ◽  
Genome Wide ◽  
Heterogeneous Tissue ◽  
Whole Transcriptome ◽  
Old Mice ◽  
Genome Wide Expression

ABSTRACTSkeletal muscle is a heterogeneous tissue. Individual myofibers that make up muscle tissue exhibit variation in their metabolic and contractile properties. Although there are biochemical and histological assays to study myofiber heterogeneity, efficient methods to analyze the whole transcriptome of individual myofibers are lacking. We have developed single myofiber RNA-Seq (smfRNA-Seq) to analyze the whole transcriptome of individual myofibers by combining single fiber isolation with Switching Mechanisms at 5’ end of RNA Template (SMART) technology. Our method provides high-resolution genome wide expression profiles of single myofibers. Using smfRNA-Seq, we have analyzed the differences in the transcriptome of young and old myofibers to validate the effectiveness of this new method. Using smfRNA-Seq, we performed comparative gene expression analysis between single myofibers from young and old mice. Our data suggests that aging leads to significant changes in the expression of metabolic and structural genes in myofibers. Our data suggests that smfRNA-Seq is a powerful tool to study developmental, disease and age-related dynamics in the composition of skeletal muscle.

scholarly journals mRNA-Seq reveals complex patterns of gene regulation and expression in the mouse skeletal muscle transcriptome associated with calorie restriction

2012 ◽  
Vol 44 (6) ◽  
pp. 331-344 ◽  
Author(s):  
Joseph M. Dhahbi ◽  
Hani Atamna ◽  
Dario Boffelli ◽  
David I. K. Martin ◽  
Stephen R. Spindler
Keyword(s):  
Skeletal Muscle ◽  
Gene Regulation ◽  
Calorie Restriction ◽  
Muscle Development ◽  
Mrna Isoforms ◽  
Age Related ◽  
Old Mice ◽  
And Oxidative Stress ◽  
Skeletal Muscle Transcriptome

Sarcopenia is an age-associated loss of skeletal muscle mass and strength that increases the risk of disability. Calorie restriction (CR), the consumption of fewer calories while maintaining adequate nutrition, mitigates sarcopenia and many other age-related diseases. To identify potential mechanisms by which CR preserves skeletal muscle integrity during aging, we used mRNA-Seq for deep characterization of gene regulation and mRNA abundance in skeletal muscle of old mice compared with old mice subjected to CR. mRNA-Seq revealed complex CR-associated changes in expression of mRNA isoforms, many of which occur without a change in total message abundance and thus would not be detected by methods other than mRNA-Seq. Functional annotation of differentially expressed genes reveals CR-associated upregulation of pathways involved in energy metabolism and lipid biosynthesis, and downregulation of pathways mediating protein breakdown and oxidative stress, consistent with earlier microarray-based studies. CR-associated changes not noted in previous studies involved downregulation of genes controlling actin cytoskeletal structures and muscle development. These CR-associated changes reflect generally healthier muscle, consistent with CR's mitigation of sarcopenia. mRNA-Seq generates a rich picture of the changes in gene expression associated with CR, and may facilitate identification of genes that are primary mediators of CR's effects.

scholarly journals Serine and Glycine Are Essential for Skeletal Muscle Regeneration Following Injury

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 81-81
Author(s):  
Anna Thalacker-Mercer ◽  
Jamie Blum ◽  
Brandon Gheller
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Essential Amino Acids ◽  
Regenerative Process ◽  
Skeletal Muscle Regeneration ◽  
Post Injury ◽  
Foreign Study ◽  
Funding Sources ◽  
Age Related ◽  
Old Mice

Abstract Objectives Skeletal muscle (SkM) regeneration post injury is reliant on SkM-specific stem cells (muscle progenitor cells [MPCs]) and a well-orchestrated myogenic program. The regenerative process is impaired with advancing age, potentiating pathological SkM remodeling (infiltration of fat and fibrotic tissues). We have previously demonstrated that the nutritionally non-essential amino acids serine (Ser) and glycine (Gly) are required for early stages of SkM regeneration (MPC proliferation). However, Ser and Gly availability (SkM and circulating) declines with aging. The objective was to test the hypothesis that reduced endogenous Ser/Gly during regeneration promotes pathological SkM remodeling in aged animals. Methods Old mice (∼20 months of age) were given a Ser/Gly depleted diet (SGdep) or an isonitrogenous, isoenergetic diet containing Ser/Gly (SGcont) for 4 weeks followed by notexin-induced injury to the tibialis anterior (TA) SkM. At 28 days post injury the TA was harvested and histological analysis of SkM morphology (H&E and immunofluorescence [IF]) and gene expression analyses (qPCR) were completed. Results Old mice receiving the SGdep diet had a shift toward reduced myofiber size and enhanced adipocyte infiltration in the SkM. Adipocyte infiltration was confirmed with IF of perilipin-1, an adipocyte marker. Uninjured mice on the SGdep diet did not demonstrate altered SkM morphology. Gene expression analysis of differentially expressed genes underlying SkM remodeling (reduced myofiber size and increased fat infiltration) with SGdep is ongoing. Conclusions Reduced Ser and Gly availability following injury instigates SkM remodeling in old mice, which could explain in part age-related impairments in SkM regeneration. This research underscores the essentiality of Ser and Gly for the SkM regenerative process particularly with advancing age. Funding Sources Canadian Institutes of Health Research Doctoral Foreign Study Award to BG.

scholarly journals CARDIAC TROPONIN T MEDIATED AUTOIMMUNE RESPONSE AND ITS ROLE IN SKELETAL MUSCLE AGING

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S882-S882
Author(s):  
Tan Zhang ◽  
Xin Feng ◽  
Bo Feng ◽  
Juan Dong ◽  
Karen Haas ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Troponin ◽  
Troponin T ◽  
Neuromuscular Diseases ◽  
Muscle Performance ◽  
Autoimmune Response ◽  
Cardiac Troponin T ◽  
Fast Skeletal Muscle ◽  
Age Related ◽  
Old Mice

Abstract Cardiac troponin T (cTnT), a key component of contractile machinery essential for muscle contraction, is also expressed in skeletal muscle under certain conditions (e.g. neuromuscular diseases and aging). We have reported that skeletal muscle cTnT regulates neuromuscular junction denervation preferentially in fast skeletal muscle of old mice. Here, we further report that cTnT is also enriched within some myofibers, and/or along microvascular walls in old mice fast skeletal muscle. Strikingly, immunoglobulin G (IgG), together with markers of complement system activation, cell death (necroptosis or apoptosis), and macrophage infiltration, were all found to be co-localized with cTnT and IgG in those areas. In addition, elevated cTnT and IgG are associated with lower dystrophin expression on muscle fiber membrane, lower muscle capillary density, and reduced muscle performance (wire hanging test). Using purified recombinant TnT proteins, we confirmed that only cTnT, but not slow or fast skeletal muscle TnT1 or TnT3, was detected by immunoblot using sera from old (but not young) mice with pre-determined elevated cTnT and IgG in their skeletal muscle, indicating the existence of anti-cTnT autoantibodies in sera (previously found in human blood) and skeletal muscle of old mice. Immunoblotting further revealed that the age related changes in skeletaI muscle cTnT and IgG are more prominent in fast skeletal muscle than in slow. Importantly, elevated cTnT and IgG were also detected in skeletal muscles from 4 older adults (65-70 yrs, IMFIT). Our finding suggests a novel autoimmune mechanism mediated by cTnT that underlies age related skeletal muscle abnormalities and dysfunction.

scholarly journals miR-181a Regulates p62/SQSTM1, Parkin and Protein DJ-1 Promoting Mitochondrial Dynamics in Skeletal Muscle Ageing

2019 ◽  
Author(s):  
Katarzyna Goljanek-Whysall ◽  
Ana Soriano-Arroquia ◽  
Rachel McCormick ◽  
Caroline Chinda ◽  
Brian McDonagh
Keyword(s):  
Skeletal Muscle ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Content ◽  
Age Related ◽  
Mitochondrial Population ◽  
Abnormal Mitochondria ◽  
Related Proteins ◽  
Old Mice ◽  
Functional Deterioration

AbstractOne of the key mechanisms underlying skeletal muscle functional deterioration during ageing is disrupted mitochondrial dynamics. Regulation of mitochondrial dynamics is essential to maintain a healthy mitochondrial population and prevent the accumulation of damaged mitochondria, however the regulatory mechanisms are poorly understood. We demonstrated loss of mitochondrial content and disrupted mitochondrial dynamics in muscle during ageing concomitant with dysregulation of miR-181a target interactions. Using functional approaches and mitoQc assay, we have established that miR-181a is an endogenous regulator of mitochondrial dynamics through concerted regulation of Park2, p62/SQSTM1 and DJ-1 in vitro. Downregulation of miR-181a with age was associated with an accumulation of autophagy-related proteins and abnormal mitochondria. Restoring miR-181a levels in old mice prevented accumulation of p62, DJ-1 and PARK2, improved mitochondrial quality and muscle function. These results provide physiological evidence for the potential of microRNA-based interventions for age-related muscle atrophy and of wider significance for diseases with disrupted mitochondrial dynamics.

scholarly journals Anti-myostatin antibody increases muscle mass and strength and improves insulin sensitivity in old mice

2016 ◽  
Vol 113 (8) ◽  
pp. 2212-2217 ◽  
Author(s):  
João-Paulo G. Camporez ◽  
Max C. Petersen ◽  
Abulizi Abudukadier ◽  
Gabriela V. Moreira ◽  
Michael J. Jurczak ◽  
...  
Keyword(s):  
Metabolic Disease ◽  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Muscle Mass ◽  
Whole Body ◽  
Skeletal Muscle Atrophy ◽  
Potential Therapeutic Target ◽  
Age Related ◽  
Skeletal Muscle Glucose Uptake ◽  
Old Mice

Sarcopenia, or skeletal muscle atrophy, is a debilitating comorbidity of many physiological and pathophysiological processes, including normal aging. There are no approved therapies for sarcopenia, but the antihypertrophic myokine myostatin is a potential therapeutic target. Here, we show that treatment of young and old mice with an anti-myostatin antibody (ATA 842) for 4 wk increased muscle mass and muscle strength in both groups. Furthermore, ATA 842 treatment also increased insulin-stimulated whole body glucose metabolism in old mice, which could be attributed to increased insulin-stimulated skeletal muscle glucose uptake as measured by a hyperinsulinemic-euglycemic clamp. Taken together, these studies provide support for pharmacological inhibition of myostatin as a potential therapeutic approach for age-related sarcopenia and metabolic disease.

scholarly journals Senescence Is Associated With Elevated Intracellular Resting [Ca2 +] in Mice Skeletal Muscle Fibers. An in vivo Study

2021 ◽  
Vol 11 ◽  
Author(s):  
Alfredo Mijares ◽  
Paul D. Allen ◽  
Jose R. Lopez
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Muscle Cells ◽  
Ros Production ◽  
Middle Aged ◽  
Age Related ◽  
Tnf Α ◽  
Intracellular Ca ◽  
Old Mice

Aging causes skeletal muscles to become atrophied, weak, and easily fatigued. Here, we have tested the hypothesis that normal aging in skeletal muscle cells is associated with Ca2+ intracellular dyshomeostasis and oxidative stress. Intracellular Ca2+ concentration ([Ca2+]i), resting intracellular Na+ concentration ([Na+]i) and reactive oxygen species (ROS) production were measured in vivo (superficial gastrocnemius fibers) using double-barreled ion-selective microelectrodes, and in vitro [isolated single flexor digitorum brevis fibers] using fluorescent ROS sensor CM-H2DCFDA in young (3 months of age), middle-aged (12 months of age), and aged (24 months of age) mice. We found an age-related increase in [Ca2+]i from 121 ± 4 nM in young muscle cells which rose to 255 ± 36 nM in middle-aged and to 409 ± 25 nM in aged cells. [Na+]i also showed an age-dependent elevation, increasing from 8 ± 0.5 mM in young muscle fibers, to 12 ± 1 mM in middle-aged and to 17 ± 1 mM in old muscle fibers. Using the fluorescent ROS sensor CM-H2DCFDA we found that these increases in intracellular cation concentrations were associated with significantly increased basal ROS production as demonstrated by age related increases in the rate of dichlorodihydrofluorescein fluorescence. To determine is this could be modified by reducing ROS and/or blocking sarcolemmal Ca2+ influx we administered flufenamic acid (FFA), a non-steroidal anti-inflammatory drug which is also a non-selective blocker of the transient receptor potential canonical channels (TRPCs), for 4 weeks to determine if this would have a beneficial effect. FFA treatment reduced both basal ROS production and muscle [Ca2+]i and [Na+]i in middle-aged and aged muscle fibers compared to fibers and muscles of untreated 12 and 24-months old mice. [Ca2+]i was reduced to 134 ± 8 nM in middle-aged muscle and to 246 ± 40 nM in muscle from aged mice. Likewise [Na+]i was reduced to 9 ± 0.7 mM in middle-aged muscles and to 13 ± 1 mM in muscle from aged mice. FFA treatment also reduced age associated increases in plasma interleukin 6 and tumor necrosis factor-alpha (TNF-α) concentrations which were elevated in 12 and 24-months old mice compared to young mice and decreased age-related muscle damage as indicated by a reduction in serum creatine kinase (CK) activity. Our data provides a direct demonstration that normal aging is associated with a significant elevation [Ca2+]i, [Na+]i, and intracellular ROS production in skeletal muscle fibers. Furthermore, the fact that FFA reduced the intracellular [Ca2+], [Na+], and ROS production as well as the elevated IL6, TNF-α, and CK levels, led us to suggest that its pharmacological effect may be related to its action both as a TRPC channel blocker and as an anti-inflammatory.

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