The NLRP3 inflammasome contributes to sarcopenia and lower muscle glycolytic potential in 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.

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Gait disturbances and muscle dysfunction in fibroblast growth factor 2 knockout mice

Scientific Reports ◽

10.1038/s41598-021-90565-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

C. Homer-Bouthiette ◽

L. Xiao ◽

Marja M. Hurley

Keyword(s):

Skeletal Muscle ◽

Growth Factor ◽

Muscle Strength ◽

Fibroblast Growth Factor ◽

Muscle Function ◽

Fibroblast Growth Factor 2 ◽

Fibroblast Growth ◽

Skeletal Muscle Function ◽

Age Related ◽

Gait Disturbances

AbstractFibroblast growth factor 2 (FGF2) is important in musculoskeletal homeostasis, therefore the impact of reduction or Fgf2 knockout on skeletal muscle function and phenotype was determined. Gait analysis as well as muscle strength testing in young and old WT and Fgf2KO demonstrated age-related gait disturbances and reduction in muscle strength that were exacerbated in the KO condition. Fgf2 mRNA and protein were significantly decreased in skeletal muscle of old WT compared with young WT. Muscle fiber cross-sectional area was significantly reduced with increased fibrosis and inflammatory infiltrates in old WT and Fgf2KO vs. young WT. Inflammatory cells were further significantly increased in old Fgf2KO compared with old WT. Lipid-related genes and intramuscular fat was increased in old WT and old Fgf2KO with a further increase in fibro-adipocytes in old Fgf2KO compared with old WT. Impaired FGF signaling including Increased β-Klotho, Fgf21 mRNA, FGF21 protein, phosphorylated FGF receptors 1 and 3, was observed in old WT and old Fgf2KO. MAPK/ ERK1/2 was significantly increased in young and old Fgf2KO. We conclude that Fgf2KO, age-related decreased FGF2 in WT mice, and increased FGF21 in the setting of impaired Fgf2 expression likely contribute to impaired skeletal muscle function and sarcopenia in mice.

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Exercise and Mitochondrial Function: Importance and InferenceA Mini Review

Current Molecular Medicine ◽

10.2174/1566524021666211129110542 ◽

2021 ◽

Vol 21 ◽

Author(s):

Vaishali K. ◽

Nitesh Kumar ◽

Vanishree Rao ◽

Rakesh Krishna Kovela ◽

Mukesh Kumar Sinha

Keyword(s):

Skeletal Muscle ◽

Mitochondrial Function ◽

Skeletal Muscles ◽

Muscle Cells ◽

Skeletal Muscle Cells ◽

Present Review ◽

Age Related ◽

Exercise Induced ◽

Mitochondrial Adaptations

: Skeletal muscles must generate and distribute energy properly in order to function perfectly. Mitochondria in skeletal muscle cells form vast networks to meet this need, and their functions may improve as a result of exercise. In the present review, we discussed exercise-induced mitochondrial adaptations, age-related mitochondrial decline, and a biomarker as a mitochondrial function indicator and exercise interference.

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Inflamma-miR-21 Negatively Regulates Myogenesis during Ageing

Antioxidants ◽

10.3390/antiox9040345 ◽

2020 ◽

Vol 9 (4) ◽

pp. 345 ◽

Cited By ~ 1

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.

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Glyconeogenic pathway in isolated skeletal muscles of rats

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y02-013 ◽

2002 ◽

Vol 80 (2) ◽

pp. 162-167 ◽

Cited By ~ 8

Author(s):

Analúcia Rampazzo Xavier ◽

José Eduardo de Salles Roselino ◽

Neusa Maria Zanon Resano ◽

Maria Antonieta Rissato Garófalo ◽

Renato Helios Migliorini ◽

...

Keyword(s):

Skeletal Muscle ◽

Pyruvate Kinase ◽

Muscle Glycogen ◽

Skeletal Muscles ◽

Phosphoenolpyruvate Carboxykinase ◽

Metabolic Flux ◽

Maximal Activity ◽

Reverse Direction ◽

Long Time ◽

Muscle Pyruvate Kinase

Although the conversion of lactate to glycogen (glyconeogenesis) in muscle was demonstrated a long time ago, the biochemical reactions responsible for this process are still a controversial matter. In the present study, advantage was taken from the specific inhibition induced by phenylalanine on muscle pyruvate kinase (PK) to investigate the role of reverse PK activity in muscle glyconeogenesis. Addition of phenylalanine to the incubation medium of a preparation of isolated, intact skeletal muscles that maintain metabolic activity for several hours reduced by 50% the rate of incorporation of [14C]lactate or [14C]bicarbonate into muscle glycogen. Muscle extracts presented high levels of maximal activity of PK in the reverse direction, which was completely blocked in the presence of phenylalanine. In contrast, mercaptopicolinic acid, an inhibitor of phosphoenolpyruvate carboxykinase (PEPCK), did not affect the incorporation of14C from either lactate or bicarbonate into muscle glycogen. Maximal PEPCK activity was much lower in muscle extracts than in gluconeogenic or glyceroneogenic tissues and was suppressed in the presence of mercaptopicolinic acid. The data suggest that a reversal of the metabolic flux through the reaction catalyzed by PK contributes to the accumulation of lactate-derived glycogen that occurs in skeletal muscle under certain physiological conditions.Key words: lactate, glyconeogenesis, skeletal muscle, reverse pyruvate kinase reaction, phenylalanine.

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

European Journal of Histochemistry ◽

10.4081/ejh.2021.3229 ◽

2021 ◽

Vol 65 (2) ◽

Cited By ~ 1

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.

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

Molecules ◽

10.3390/molecules26216410 ◽

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.

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Effects of Resvega on Inflammasome Activation in Conjunction with Dysfunctional Intracellular Clearance in Retinal Pigment Epithelial (RPE) Cells

Antioxidants ◽

10.3390/antiox10010067 ◽

2021 ◽

Vol 10 (1) ◽

pp. 67

Author(s):

Niina Bhattarai ◽

Niina Piippo ◽

Sofia Ranta-aho ◽

Yashavanthi Mysore ◽

Kai Kaarniranta ◽

...

Keyword(s):

Nlrp3 Inflammasome ◽

Retinal Pigment ◽

Membrane Integrity ◽

Age Related Macular Degeneration ◽

Inflammasome Activation ◽

Rpe Cells ◽

Caspase 1 ◽

Protein Clearance ◽

Age Related ◽

Nlrp3 Inflammasome Activation

Age-related macular degeneration (AMD) is an eye disease in which retinal pigment epithelium (RPE) cells play a crucial role in maintaining retinal homeostasis and photoreceptors’ functionality. During disease progression, there is increased inflammation with nucleotide-binding domain, leucine-rich repeat, and Pyrin domain 3 (NLRP3) inflammasome activation, oxidative stress, and impaired autophagy in RPE cells. Previously, we have shown that the dietary supplement Resvega reduces reactive oxygen species (ROS) production and induces autophagy in RPE cells. Here, we investigated the ability of Resvega to prevent NLRP3 inflammasome activation with impaired protein clearance in human RPE cells. Cell viability was measured using the lactate dehydrogenase (LDH) and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Enzyme-linked immunosorbent assays (ELISA) were utilized to determine the secretion of cytokines, NLRP3, and vascular endothelial growth factor (VEGF). Caspase-1 activity was measured with a fluorescent labeled inhibitor of caspase-1 (FLICA; FAM-YVAD-FMK) and detected microscopically. Resvega improved the cell membrane integrity, which was evident as reduced LDH leakage from cells. In addition, the caspase-1 activity and NLRP3 release were reduced, as was the secretion of two inflammatory cytokines, interleukin (IL)-1β and IL-8, in IL-1α-primed ARPE-19 cells. According to our results, Resvega can potentially reduce NLRP3 inflammasome-mediated inflammation in RPE cells with impaired protein clearance.

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Implication of the NLRP3 Inflammasome in Bovine Age-Related Sarcopenia

International Journal of Molecular Sciences ◽

10.3390/ijms22073609 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3609

Author(s):

Davide De Biase ◽

Giuseppe Piegari ◽

Francesco Prisco ◽

Ilaria Cimmino ◽

Ilaria d’Aquino ◽

...

Keyword(s):

Skeletal Muscle ◽

Nlrp3 Inflammasome ◽

Interleukin 1Β ◽

Inflammasome Activation ◽

Interleukin 18 ◽

Necrosis Factor Alpha ◽

Age Related ◽

Factor Alpha ◽

Bovine Skeletal Muscle ◽

First Time

Sarcopenia is defined as the age-related loss of skeletal muscle mass, quality, and strength. The pathophysiological mechanisms underlying sarcopenia are still not completely understood. The aim of this work was to evaluate, for the first time, the expression of NLRP3 inflammasome in bovine skeletal muscle in order to investigate the hypothesis that inflammasome activation may trigger and sustain a pro-inflammatory environment leading to sarcopenia. Samples of skeletal muscle were collected from 60 cattle belonging to three age-based groups. Morphologic, immunohistochemical and molecular analysis were performed to assess the presence of age-related pathologic changes and chronic inflammation, the expression of NLRP3 inflammasome and to determine the levels of interleukin-1β, interleukin-18 and tumor necrosis factor alpha in muscle tissue. Our results revealed the presence of morphologic sarcopenia hallmark, chronic lymphocytic inflammation and a type II fibers-selective NLRP3 expression associated to a significant decreased number of immunolabeled-fibers in aged animals. Moreover, we found a statistically significant age-related increase of pro-inflammatory cytokines such as interleukin-1β and interleukin-18 suggesting the activation of NLRP3 inflammasome. Taken together, our data suggest that NLRP3 inflammasome components may be normally expressed in skeletal muscle, but its priming and activation during aging may contribute to enhance a pro-inflammatory environment altering normal muscular anabolism and metabolism.

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

10.1101/724393 ◽

2019 ◽

Cited By ~ 1

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.

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Global phosphoproteomic profiling of skeletal muscle in ovarian hormone-deficient female mice

Innovation in Aging ◽

10.1093/geroni/igab046.2526 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. 675-676

Author(s):

Mina Peyton ◽

Tzu-Yi Yang ◽

LeeAnn Higgins ◽

Todd Markowski ◽

Laurie Parker ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Strength ◽

Contractile Function ◽

Fiber Type ◽

Tibialis Anterior Muscle ◽

Estrogen Deficiency ◽

Post Translational Modification ◽

Coupling Energy ◽

Age Related ◽

Skeletal Muscle Strength

Abstract Dynapenia, the age-related loss of skeletal muscle strength without the loss of muscle mass, significantly impacts the activities and quality of life of the aging population. Studies have shown that dynapenia occurs earlier in females than males in both human and rodent studies. Moreover, in females, estrogen deficiency has been shown to contribute to the loss of skeletal muscle strength as well as blunted recovery of strength after injury. The maintenance of skeletal muscle contractile function is vital to the overall health of women, especially as women live 1/3 of their life in an estrogen deficient state. Reversible protein phosphorylation is an indispensable post-translational modification, playing a key role in signal transduction pathways. Phosphorylation of skeletal muscle proteins have been shown to regulate sarcomeric function, excitation-contraction coupling, energy metabolism, and fiber-type composition. To define the physiological changes in the skeletal muscle phosphoproteome associated with estrogen deficiency, we used an ovariectomy model coupled with mass spectrometry. We identified, in total, 5,424 unique phosphorylation sites and 1,177 phosphoproteins in the tibialis anterior muscle. Ingenuity Pathway Analysis show decreased phosphorylation of contractile proteins and significant predicted inhibition of the upstream kinase, CDK6 (z-score -2.0) in ovariectomized compared to control muscles. Our results suggest that estrogen deficiency remodels the skeletal muscle phosphoproteome which may alter phosphorylation signaling that might contribute to the loss of strength in females.

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