bims-moremu 2024-01-28 papers

bims-moremu

Biomed News

on Molecular regulators of muscle mass

Issue of 2024–01–28
27 papers selected by
Anna Vainshtein, Craft Science Inc.

Postnatal Pdzrn3 deficiency causes acute muscle atrophy without alterations in endplate morphology.
CREG1 deficiency impaired myoblast differentiation and skeletal muscle regeneration.
Peroxisome proliferator-activated receptor γ coactivator 1α regulates downstream of tyrosine kinase-7 (Dok-7) expression important for neuromuscular junction formation.
Translatability of mouse muscle-aging for humans: the role of sex.
Skeletal muscle reprogramming enhances reinnervation after peripheral nerve injury.
CD155 is essential for skeletal muscle regeneration by regulating satellite cell proliferation and differentiation.
Murine myoblasts exposed to SYUIQ-5 acquire senescence phenotype and differentiate into sarcopenic-like myotubes, an in vitro study.
Ursolic Acid Induces Beneficial Changes in Skeletal Muscle mRNA Expression and Increases Exercise Participation and Performance in Dogs with Age-Related Muscle Atrophy.
The function of previously unappreciated exerkines secreted by muscle in regulation of neurodegenerative diseases.
FGF21 induces skeletal muscle atrophy and increases amino acids in female mice: a potential role for glucocorticoids.
PGC-1α activation boosts exercise-dependent cellular response in the skeletal muscle.
Macrophage SREBP1 regulates skeletal muscle regeneration.
High-throughput Analysis of Capillary Density in Skeletal Muscle Cross Sections.
Bezafibrate attenuates immobilization-induced muscle atrophy in mice.
The plasma metabolome is associated with preservation of physiological function following lifelong aerobic exercise in mice.
How Can Proteomics Help to Elucidate the Pathophysiological Crosstalk in Muscular Dystrophy and Associated Multi-System Dysfunction?
Generation of a human ACTA1-tdTomato reporter iPSC line using CRISPR/Cas9 editing.
A mito-centric view on muscle aging and function.
PIGB maintains nuclear lamina organization in skeletal muscle of Drosophila.
Exploring Frontiers in Musculoskeletal Biology and Bioengineering: Editorial Focus.
Regional and bilateral MRI and gene signatures in facioscapulohumeral dystrophy: implications for clinical trial design and mechanisms of disease progression.
Impact of Exercise Intensity on Cerebral BDNF Levels: Role of FNDC5/Irisin.
Propofol directly binds and inhibits skeletal muscle ryanodine receptor 1 (RyR1).
The role of non-coding RNAs in muscle aging: regulatory mechanisms and therapeutic potential.
Denervation-Induced Sarcopenia Model.
Sucrose-Enriched and Carbohydrate-Free High-Fat Diets Distinctly Affect Substrate Metabolism in Oxidative and Glycolytic Muscles of Rats.
Active vitamin D increases myogenic differentiation in C2C12 cells via a vitamin D response element on the myogenin promoter.

Biochem Biophys Res Commun. 2024 Jan 17. pii: S0006-291X(24)00077-9. [Epub ahead of print]696 149542

Postnatal Pdzrn3 deficiency causes acute muscle atrophy without alterations in endplate morphology.

Minako Kawai-Takaishi, Yoshihiro Miyagawa, Takeshi Honda, Makoto Inui, Tohru Hosoyama.

  PDZ domain-containing RING finger family protein 3 (PDZRN3) is expressed in various tissues, including the skeletal muscle. Although PDZRN3 plays a crucial role in the terminal differentiation of myoblasts and synaptic growth/maturation in myogenesis, the role of this molecule in postnatal muscles is completely unknown despite its lifelong expression in myofibers. In this study, we aimed to elucidate the function of PDZRN3 in mature myofibers using myofiber-specific conditional knockout mice. After tamoxifen injection, PDZRN3 deficiency was confirmed in both fast and slow myofibers of Myf6-CreERT2; Pdzrn3flox/flox (Pdzrn3mcKO) mice. Transcriptome analysis of the skeletal muscles of Pdzrn3mcKO mice identified differentially expressed genes, including muscle atrophy-related genes such as Smox, Amd1/2, and Mt1/2, suggesting that PDZRN3 is involved in the homeostatic maintenance of postnatal muscles. PDZRN3 deficiency caused muscle atrophy, predominantly in fast-twitch (type II) myofibers, and reduced muscle strength. While myofiber-specific PDZRN3 deficiency did not influence endplate morphology or expression of neuromuscular synaptic formation-related genes in postnatal muscles, indicating that the relationship between PDZRN3 and neuromuscular junctions might be limited during muscle development. Considering that the expression of Pdzrn3 in skeletal muscles was significantly lower in aged mice than in mature adult mice, we speculated that the PDZRN3-mediated muscle maintenance system might be associated with the pathophysiology of age-related muscle decline, such as sarcopenia.

Keywords:  Endplate; Muscle atrophy; Muscle strength; PDZRN3; Postnatal muscle

DOI:  https://doi.org/10.1016/j.bbrc.2024.149542
J Cachexia Sarcopenia Muscle. 2024 Jan 25.

CREG1 deficiency impaired myoblast differentiation and skeletal muscle regeneration.

Haixu Song, Xiaoxiang Tian, Lianqi He, Dan Liu, Jiayin Li, Zhu Mei, Ting Zhou, Chunying Liu, Jiaqi He, Xiaodong Jia, Zheming Yang, Chenghui Yan, Yaling Han.

   BACKGROUND: CREG1 (cellular repressor of E1A-stimulated genes 1) is a protein involved in cellular differentiation and homeostasis regulation. However, its role in skeletal muscle satellite cells differentiation and muscle regeneration is poorly understood. This study aimed to investigate the role of CREG1 in myogenesis and muscle regeneration.
METHODS: RNA sequencing data (GSE8479) was analysed from the Gene Expression Omnibus database (GEO, https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi). We generated Creg1 knockdown and skeletal muscle satellite cells specific Creg1 overexpression mice mediated by adeno-associated virus serotype 9 (AAV9), skeletal muscle mature myofibre Creg1 knockout mice (myoblast/Creg1MKO), and control mice Creg1flox/flox (Creg1fl/fl ) as in vivo models. The mice were injected into tibialis anterior (TA) muscle with 100 μL of 10 μM cardiotoxin to establish a muscle regeneration model. Creg1fl/fl and Creg1MKO mice were treated with AAV-sh-C-Cbl (2 × 1010 genomic copies/mouse) to silence C-Cbl in the TA muscle. 293T and C2C12 cells were transfected with plasmids using lipofectamine RNAi MAX in vitro. Mass spectrometry analyses and RNA sequencing transcriptomic assay were performed.
RESULTS: We analysed the transcriptional profiles of the skeletal muscle biopsies from healthy older (N = 25) and younger (N = 26) adult men and women in GSE8479 database, and the results showed that Creg1 was associated with human sarcopenia. We found that Creg1 knockdown mice regenerated less newly formed fibres in response to cardiotoxin injection (~30% reduction, P < 0.01); however, muscle satellite cells specific Creg1 overexpression mice regenerated more newly formed fibres (~20% increase, P < 0.05). AMPKa1 is known as a key mediator in the muscle regeneration process. Our results revealed that CREG1 deficiency inhibited AMPKa1 signalling through C-CBL E3-ubiquitin ligase-mediated AMPKa1 degradation (P < 0.01). C-CBL-mediated AMPKa1 ubiquitination was attributed to the K48-linked polyubiquitination of AMPKa1 at K396 and that the modification played an important role in the regulation of AMPKa1 protein stability. We also found that Creg1MKO mice regenerated less newly formed fibres compared with Creg1fl/fl mice (~30% reduction, P < 0.01). RNA-seq analysis showed that CREG1 deletion in impaired muscles led to the upregulation of inflammation and DKK3 expression. The TA muscles of Creg1MKO mice were injected with AAV-vector or AAV-shC-Cbl, silencing C-CBL (P < 0.01) in the skeletal muscles of Creg1MKO mice significantly improved muscle regeneration induced by CTX injury (P < 0.01).
CONCLUSIONS: Our findings suggest that CREG1 may be a potential therapeutic target for skeletal muscle regeneration.

Keywords:  AMPKa1; C-CBL; CREG1; Satellite cells; Skeletal muscle regeneration

DOI:  https://doi.org/10.1002/jcsm.13427
Sci Rep. 2024 01 20. 14(1): 1780

Peroxisome proliferator-activated receptor γ coactivator 1α regulates downstream of tyrosine kinase-7 (Dok-7) expression important for neuromuscular junction formation.

Takumi Sugimoto, Chihiro Sakamaki, Tokushi Kimura, Takahiro Eguchi, Shinji Miura, Yasutomi Kamei.

The neuromuscular junction (NMJ)-formed between a motor nerve terminal and skeletal muscle fiber-plays an important role in muscle contraction and other muscle functions. Aging and neurodegeneration worsen NMJ formation and impair muscle function. Downstream of tyrosine kinase-7 (Dok-7), expressed in skeletal muscle fibers, is essential for the formation of NMJ. Exercise increases the expression of the transcriptional coactivator peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) in skeletal muscles and restores NMJ formation. In this study, we used skeletal muscle-specific PGC1α knockout or overexpression mice to examine the role of PGC1α in regulating Dok-7 expression and NMJ formation. Our findings revealed that Dok-7 expression is regulated by PGC1α, and luciferase activity of the Dok-7 promoter is greatly increased by coexpressing PGC1α and estrogen receptor-related receptor α. Thus, we suggest PGC1α is involved in exercise-mediated restoration of NMJ formation.

DOI: https://doi.org/10.1038/s41598-024-52198-x
Geroscience. 2024 Jan 24.

Translatability of mouse muscle-aging for humans: the role of sex.

Jelle C B C de Jong, Martien P M Caspers, Nicole Worms, Nanda Keijzer, Robert Kleemann, Aswin L Menke, Arie G Nieuwenhuizen, Jaap Keijer, Lars Verschuren, Anita M van den Hoek.

  Muscle-aging drives sarcopenia and is a major public health issue. Mice are frequently used as a model for human muscle-aging, however, research investigating their translational value is limited. In addition, mechanisms underlying muscle-aging may have sex-specific features in humans, but it is not yet assessed whether these are recapitulated in mice. Here, we studied the effects of aging on a functional, histological and transcriptional level at multiple timepoints in male and female mice (4, 17, 21 and 25 months), with particular emphasis on sex-differences. The effects of natural aging on the transcriptome of quadriceps muscle were compared to humans on pathway level. Significant loss of muscle mass occurred late, at 25 months, in both male (-17%, quadriceps) and female mice (-10%, quadriceps) compared to young control mice. Concomitantly, we found in female, but not male mice, a slower movement speed in the aged groups compared to the young mice (P < 0.001). Consistently, weighted gene co-expression network analysis revealed a stronger association between the aging-related reduction of movement and aging-related changes in muscle transcriptome of female compared to male mice (P < 0.001). In male, but not female mice, major distinctive aging-related changes occurred in the last age group (25 months), which highlights the necessity for careful selection of age using mice as a muscle-aging model. Furthermore, contrasting to humans, more aging-related changes were found in the muscle transcriptome of male mice compared to female mice (4090 vs. 2285 differentially expressed genes at 25 months, respectively). Subsequently, male mice recapitulated more muscle-aging related pathways characteristic for both male and female humans. In conclusion, our data show that sex has a critical effect on the mouse muscle-aging trajectory, although these do not necessarily reflect sex differences observed in the human muscle-aging trajectory.

Keywords:  Frailty; Gender; Muscle atrophy; Physical activity; Sarcopenia

DOI:  https://doi.org/10.1007/s11357-024-01082-7
Res Sq. 2024 Jan 05. pii: rs.3.rs-3463557. [Epub ahead of print]

Skeletal muscle reprogramming enhances reinnervation after peripheral nerve injury.

Kirkwood Personius, Pihu Mehrotra, James Jablonski, John Toftegard, Yali Zhang, Shahryar Shahini, Jianmin Wang, Carey Hung, Reilly Ellis, Gabriella Kayal, Nika Rajabian, Song Liu, Kelly Roballo, Susan Udin, Stelios Andreadis.

Peripheral Nerve Injuries (PNI) affect more than 20 million Americans and severely impact quality of life by causing long-term disability. The onset of PNI is characterized by nerve degeneration distal to the nerve injury resulting in long periods of skeletal muscle denervation. During this period, muscle fibers atrophy and frequently become incapable of "accepting" innervation because of the slow speed of axon regeneration post injury. We hypothesize that reprogramming the skeletal muscle to an embryonic-like state may preserve its reinnervation capability following PNI. To this end, we generated a mouse model in which NANOG, a pluripotency-associated transcription factor can be expressed locally upon delivery of doxycycline (Dox) in a polymeric vehicle. NANOG expression in the muscle upregulated the percentage of Pax7+ nuclei and expression of eMYHC along with other genes that are involved in muscle development. In a sciatic nerve transection model, NANOG expression led to upregulation of key genes associated with myogenesis, neurogenesis and neuromuscular junction (NMJ) formation, and downregulation of key muscle atrophy genes. Further, NANOG mice demonstrated extensive overlap between synaptic vesicles and NMJ acetylcholine receptors (AChRs) indicating restored innervation. Indeed, NANOG mice showed greater improvement in motor function as compared to wild-type (WT) animals, as evidenced by improved toe-spread reflex, EMG responses and isometric force production. In conclusion, we demonstrate that reprogramming the muscle can be an effective strategy to improve reinnervation and functional outcomes after PNI.

DOI: https://doi.org/10.21203/rs.3.rs-3463557/v1
FASEB J. 2024 Jan 31. 38(2): e23440

CD155 is essential for skeletal muscle regeneration by regulating satellite cell proliferation and differentiation.

Wenpeng Li, Yuan Zhang, Yitian Liu, Chongyang Feng, Chujun Duan, Zhixiang Zhang, Peng Zhao, Ran Zhuang, Yong Ding.

CD155, a member of the immunoglobulin superfamily, is closely related to cell proliferation, adhesion, and migration. CD155 is overexpressed on the surface of cancer cells to promote cell proliferation and is upregulated in damaged tissues as a stress-induced molecule. The process of skeletal muscle regeneration after injury is complex and involves injurious stimulation and subsequent satellite cell proliferation. However, the role of CD155 in this process remains unelucidated. This study aimed to explore the role of CD155 in injured skeletal muscle regeneration and to clarify its effect on satellite cell proliferation and differentiation. Here, quantitative real-time polymerase chain reaction (RT-qPCR) and immunofluorescence results indicated that CD155 expression in satellite cells increased after skeletal muscle injury. CD155 knockout in mice impaired the regeneration of skeletal muscle. A bone marrow transplantation mouse model was constructed and revealed that CD155 on skeletal muscle tissues, not immune cells, affected muscle regeneration. In vitro, CD155 knockdown in myoblasts inhibited their proliferation and differentiation. The transcriptomic analysis also indicated that CD155 absence can impair the biological proliferation and differentiation process of myoblasts. Our research demonstrates that CD155 directly promotes injured muscle regeneration by regulating satellite cell proliferation and differentiation, which may be a potential therapeutic molecule for skeletal muscle injury.

DOI: https://doi.org/10.1096/fj.202201779RRR
J Gerontol A Biol Sci Med Sci. 2024 Jan 24. pii: glae022. [Epub ahead of print]

Murine myoblasts exposed to SYUIQ-5 acquire senescence phenotype and differentiate into sarcopenic-like myotubes, an in vitro study.

Laura Gerosa, Amir Mohammad Malvandi, Marta Gomarasca, Chiara Verdelli, Veronica Sansoni, Martina Faraldi, Ewa Ziemann, Fabiola Olivieri, Giuseppe Banfi, Giovanni Lombardi.

  The musculoskeletal system is one of the most affected organs by aging that correlates well with an accumulation of senescent cells as for other multiple age related pathologies. The molecular mechanisms underpinning muscle impairment because of senescent cells are still elusive. Availability of in vitro model of skeletal muscle senescence is limited and restricted to a small panel of phenotypic features of these senescent cells in vivo. Here, we developed a new in vitro model of senescent C2C12 mouse myoblasts that, when subjected to differentiation, the resulting myotubes showed sarcopenic features. To induce senescence, we used SYUIQ-5, a quindoline derivative molecule inhibitor of telomerase activity, leading to the expression of several senescent hallmarks in treated myoblasts. They had increased levels of p21 protein accordingly with the observed cell cycle arrest. Further, they had enhanced SA-βgalactosidase enzyme activity and phosphorylation of p53 and histone H2AX. SYUIQ-5 senescent myoblasts had impaired differentiation potential and the resulting myotubes showed increased levels of ATROGIN-1 and MURF1, ubiquitin ligases components responsible of protein degradation, and decreased mitochondria content, typical features of sarcopenic muscles. Myotubes differentiated from senescent myoblasts cultures release increased levels of MYOSTATIN that could affect skeletal muscle cell growth. Overall, our data suggest that a greater burden of senescent muscle cells could contribute to sarcopenia. This study presents a well-defined in vitro model of muscle cell senescence useful for deeper investigation in the aging research field to discover new putative therapeutic targets and senescence biomarkers associated with aged musculoskeletal system.

Keywords:   in vitro model; SYUIQ-5; sarcopenic myotubes; senescence; senescent myoblasts

DOI:  https://doi.org/10.1093/gerona/glae022
Animals (Basel). 2024 Jan 05. pii: 186. [Epub ahead of print]14(2):

Ursolic Acid Induces Beneficial Changes in Skeletal Muscle mRNA Expression and Increases Exercise Participation and Performance in Dogs with Age-Related Muscle Atrophy.

Scott M Ebert, Celine S Nicolas, Paul Schreiber, Jaime G Lopez, Alan T Taylor, Andrew R Judge, Sarah M Judge, Blake B Rasmussen, John J Talley, Christophe A Rème, Christopher M Adams.

  Muscle atrophy and weakness are prevalent and debilitating conditions in dogs that cannot be reliably prevented or treated by current approaches. In non-canine species, the natural dietary compound ursolic acid inhibits molecular mechanisms of muscle atrophy, leading to improvements in muscle health. To begin to translate ursolic acid to canine health, we developed a novel ursolic acid dietary supplement for dogs and confirmed its safety and tolerability in dogs. We then conducted a randomized, placebo-controlled, proof-of-concept efficacy study in older beagles with age-related muscle atrophy, also known as sarcopenia. Animals received placebo or ursolic acid dietary supplements once a day for 60 days. To assess the study's primary outcome, we biopsied the quadriceps muscle and quantified atrophy-associated mRNA expression. Additionally, to determine whether the molecular effects of ursolic acid might have functional correlates consistent with improvements in muscle health, we assessed secondary outcomes of exercise participation and T-maze performance. Importantly, in canine skeletal muscle, ursolic acid inhibited numerous mRNA expression changes that are known to promote muscle atrophy and weakness. Furthermore, ursolic acid significantly improved exercise participation and T-maze performance. These findings identify ursolic acid as a natural dietary compound that inhibits molecular mechanisms of muscle atrophy and improves functional performance in dogs.

Keywords:  activity; cachexia; canine; dietary supplement; dog; exercise; muscle atrophy; sarcopenia; skeletal muscle; ursolic acid

DOI:  https://doi.org/10.3390/ani14020186
Front Mol Neurosci. 2023 ;16 1305208

The function of previously unappreciated exerkines secreted by muscle in regulation of neurodegenerative diseases.

Xuepeng Bian, Qian Wang, Yibing Wang, Shujie Lou.

  The initiation and progression of neurodegenerative diseases (NDs), distinguished by compromised nervous system integrity, profoundly disrupt the quality of life of patients, concurrently exerting a considerable strain on both the economy and the social healthcare infrastructure. Exercise has demonstrated its potential as both an effective preventive intervention and a rehabilitation approach among the emerging therapeutics targeting NDs. As the largest secretory organ, skeletal muscle possesses the capacity to secrete myokines, and these myokines can partially improve the prognosis of NDs by mediating the muscle-brain axis. Besides the well-studied exerkines, which are secreted by skeletal muscle during exercise that pivotally exert their beneficial function, the physiological function of novel exerkines, e.g., apelin, kynurenic acid (KYNA), and lactate have been underappreciated previously. Herein, this review discusses the roles of these novel exerkines and their mechanisms in regulating the progression and improvement of NDs, especially the significance of their functions in improving NDs' prognoses through exercise. Furthermore, several myokines with potential implications in ameliorating ND progression are proposed as the future direction for investigation. Elucidation of the function of exerkines secreted by skeletal muscle in the regulation of NDs advances the understanding of its pathogenesis and facilitates the development of therapeutics that intervene in these processes to cure NDs.

Keywords:  KYNA; apelin; exercise; lactate; myokine; neurodegenerative disease

DOI:  https://doi.org/10.3389/fnmol.2023.1305208
Endocrinology. 2024 Jan 19. pii: bqae004. [Epub ahead of print]

FGF21 induces skeletal muscle atrophy and increases amino acids in female mice: a potential role for glucocorticoids.

Karlton R Larson, Devi Jayakrishnan, Karla A Soto Sauza, Michael L Goodson, Aki T Chaffin, Arik Davidyan, Suraj Pathak, Yanbin Fang, Diego Gonzalez Magaña, Benjamin F Miller, Karen K Ryan.

  Fibroblast growth factor-21 (FGF21) is an intercellular signaling molecule secreted by metabolic organs, including skeletal muscle, in response to intracellular stress. FGF21 crosses the blood brain barrier and acts via the nervous system to coordinate aspects of the adaptive starvation response, including increased lipolysis, gluconeogenesis, fatty acid oxidation, and activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. Given its beneficial effects for hepatic lipid metabolism, pharmaceutical FGF21 analogues are in clinical trials treatment of fatty liver disease. We predicted pharmacologic treatment with FGF21 increases HPA axis activity and skeletal muscle glucocorticoid signaling and induces skeletal muscle atrophy in mice. Here we found a short course of systemic FGF21 treatment decreased muscle protein synthesis and reduced tibialis anterior weight; this was driven primarily by its effect in female mice. Similarly, intracerebroventricular FGF21 reduced TA muscle fiber cross sectional area; this was more apparent among female mice compared to male littermates. In agreement with the reduced muscle mass, the topmost enriched metabolic pathways in plasma collected from FGF21-treated females were related to amino acid metabolism, and the relative abundance of plasma proteinogenic amino acids were increased up to three-fold. FGF21 treatment increased hypothalamic Crh mRNA, plasma corticosterone, and adrenal weight, and increased expression of glucocorticoid receptor target genes known to reduce muscle protein synthesis and/or promote degradation. Given the proposed use of FGF21 analogues for the treatment of metabolic disease, the study is both physiologically relevant and may have important clinical implications.

Keywords:  FGF21; HPA axis; glucocorticoid; muscle; protein restriction; stress

DOI:  https://doi.org/10.1210/endocr/bqae004
J Physiol Biochem. 2024 Jan 23.

PGC-1α activation boosts exercise-dependent cellular response in the skeletal muscle.

Soroosh Mozaffaritabar, Erika Koltai, Lei Zhou, Zoltan Bori, Attila Kolonics, Sylwester Kujach, Yaodong Gu, Atsuko Koike, Anita Boros, Zsolt Radák.

  The role of Peroxisome proliferator-activated receptor-gamma coactivator alpha (PGC-1α) in fat metabolism is not well known. In this study, we compared the mechanisms of muscle-specific PGC-1α overexpression and exercise-related adaptation-dependent fat metabolism. PGC-1α trained (PGC-1α Ex) and wild-trained (wt-ex) mice were trained for 10 weeks, five times a week at 30 min per day with 60 percent of their maximal running capacity. The PGC-1α overexpressed animals exhibited higher levels of Fibronectin type III domain-containing protein 5 (FNDC5), 5' adenosine monophosphate-activated protein kinase alpha (AMPK-α), the mammalian target of rapamycin (mTOR), Sirtuin 1 (SIRT1), Lon protease homolog 1 (LONP1), citrate synthase (CS), succinate dehydrogenase complex flavoprotein subunit A (SDHA), Mitofusin-1 (Mfn1), endothelial nitric oxide synthase (eNOS), Hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL), G protein-coupled receptor 41 (GPR41), and Phosphatidylcholine Cytidylyltransferase 2 (PCYT2), and lower levels of Sirtuin 3 (SIRT3) compared to wild-type animals. Exercise training increased the protein content levels of SIRT1, HSL, and ATGL in both the wt-ex and PGC-1α trained groups. PGC-1α has a complex role in cellular signaling, including the upregulation of lipid metabolism-associated proteins. Our data reveals that although exercise training mimics the effects of PGC-1α overexpression, it incorporates some PGC-1α-independent adaptive mechanisms in fat uptake and cell signaling.

Keywords:  Exercise; Lipid Metabolism; Mitochondrial function; PGC-1α overexpression; Skeletal muscle

DOI:  https://doi.org/10.1007/s13105-024-01006-1
Front Immunol. 2023 ;14 1251784

Macrophage SREBP1 regulates skeletal muscle regeneration.

Yumiko Oishi, Hiroyuki Koike, Naoki Kumagami, Yoshimi Nakagawa, Masaya Araki, Yoshitaka Taketomi, Yoshimi Miki, Shigeru Matsuda, Takashi Matsuzaka, Hitoshi Ozawa, Hitoshi Shimano, Makoto Murakami, Ichiro Manabe.

  Macrophages are essential for the proper inflammatory and reparative processes that lead to regeneration of skeletal muscle after injury. Recent studies have demonstrated close links between the function of activated macrophages and their cellular metabolism. Sterol regulatory element-binding protein 1 (SREBP1) is a key regulator of lipid metabolism and has been shown to affect the activated states of macrophages. However, its role in tissue repair and regeneration is poorly understood. Here we show that systemic deletion of Srebf1, encoding SREBP1, or macrophage-specific deletion of Srebf1a, encoding SREBP1a, delays resolution of inflammation and impairs skeletal muscle regeneration after injury. Srebf1 deficiency impairs mitochondrial function in macrophages and suppresses the accumulation of macrophages at sites of muscle injury. Lipidomic analyses showed the reduction of major phospholipid species in Srebf1 -/- muscle myeloid cells. Moreover, diet supplementation with eicosapentaenoic acid restored the accumulation of macrophages and their mitochondrial gene expression and improved muscle regeneration. Collectively, our results demonstrate that SREBP1 in macrophages is essential for repair and regeneration of skeletal muscle after injury and suggest that SREBP1-mediated fatty acid metabolism and phospholipid remodeling are critical for proper macrophage function in tissue repair.

Keywords:  EPA - 20:5n-3; SREBP (sterol regulatory element-binding protein) pathway; fatty acid metabolism; macrophage; skeletal muscle regeneration

DOI:  https://doi.org/10.3389/fimmu.2023.1251784
Bio Protoc. 2024 Jan 20. 14(2): e4922

High-throughput Analysis of Capillary Density in Skeletal Muscle Cross Sections.

Tooba Abbassi-Daloii, Sander D Mallon, Salma El Abdellaoui, Lenard M Voortman, Vered Raz.

  Capillary density in skeletal muscles is key to estimate exercise capacity in healthy individuals, athletes, and those with muscle-related pathologies. Here, we present a step-by-step, high-throughput semi-automated method for quantifying capillary density from whole human skeletal muscle cross-sections, in areas of the muscle occupied by myofibers. We provide a detailed protocol for immunofluorescence staining, image acquisition, processing, and quantification. Image processing is performed in ImageJ, and data analysis is conducted in R. The provided protocol allows high-throughput quantification of capillary density. Key features • This protocol builds upon the method and results described in Abbassi-Daloii et al. (2023b). • It includes step-by-step details on image acquisition and image processing of the entire muscle section. • It enables high-throughput and semi-automated image quantification of capillary density. • It provides a robust analysis for determining capillary density over the entire muscle cross section.

Keywords:  CD31; Capillary density; Endoglin; Image quantification; Immunofluorescence; Skeletal muscle

DOI:  https://doi.org/10.21769/BioProtoc.4922
Sci Rep. 2024 Jan 26. 14(1): 2240

Bezafibrate attenuates immobilization-induced muscle atrophy in mice.

Satoshi Nakamura, Yuiko Sato, Tami Kobayashi, Akihito Oya, Astuhiro Fujie, Morio Matsumoto, Masaya Nakamura, Arihiko Kanaji, Takeshi Miyamoto.

Muscle atrophy due to fragility fractures or frailty worsens not only activity of daily living and healthy life expectancy, but decreases life expectancy. Although several therapeutic agents for muscle atrophy have been investigated, none is yet in clinical use. Here we report that bezafibrate, a drug used to treat hyperlipidemia, can reduce immobilization-induced muscle atrophy in mice. Specifically, we used a drug repositioning approach to screen 144 drugs already utilized clinically for their ability to inhibit serum starvation-induced elevation of Atrogin-1, a factor related to muscle atrophy, in myotubes in vitro. Two candidates were selected, and here we demonstrate that one of them, bezafibrate, significantly reduced muscle atrophy in an in vivo model of muscle atrophy induced by leg immobilization. In gastrocnemius muscle, immobilization reduced muscle weight by an average of ~ 17.2%, and bezafibrate treatment prevented ~ 40.5% of that atrophy. In vitro, bezafibrate significantly inhibited expression of the inflammatory cytokine Tnfa in lipopolysaccharide-stimulated RAW264.7 cells, a murine macrophage line. Finally, we show that expression of Tnfa and IL-1b is induced in gastrocnemius muscle in the leg immobilization model, an activity significantly antagonized by bezafibrate administration in vivo. We conclude that bezafibrate could serve as a therapeutic agent for immobilization-induced muscle atrophy.

DOI: https://doi.org/10.1038/s41598-024-52689-x
Geroscience. 2024 Jan 24.

The plasma metabolome is associated with preservation of physiological function following lifelong aerobic exercise in mice.

Kevin O Murray, Grace S Maurer, Rachel A Gioscia-Ryan, Melanie C Zigler, Katelyn R Ludwig, Angelo D'Alessandro, Julie A Reisz, Matthew J Rossman, Douglas R Seals, Zachary S Clayton.

  Declines in physiological function with aging are strongly linked to age-related diseases. Lifelong voluntary aerobic exercise (LVAE) preserves physiological function with aging, possibly by increasing cellular quality control processes, but the circulating molecular transducers mediating these processes are incompletely understood. The plasma metabolome may predict biological aging and is impacted by a single bout of aerobic exercise. Here, we conducted an ancillary analysis using plasma samples, and physiological function data, from previously reported studies of LVAE in male C57BL/6N mice randomized to LVAE (wheel running) or sedentary (SED) (n = 8-9/group) to determine if LVAE alters the plasma metabolome and whether these changes correlated with preservation of physiological function with LVAE. Physical function (grip strength, coordination, and endurance) was assessed at 3 and 18 months of age; vascular endothelial function and the plasma metabolome were assessed at 19 months. Physical function was preserved (%decline; mean ± SEM) with LVAE vs SED (all p < 0.05)-grip strength, 0.4 ± 1.7% vs 12 ± 4.0%; coordination, 10 ± 4% vs 73 ± 10%; endurance, 1 ± 15% vs 61 ± 5%. Vascular endothelial function with LVAE (88.2 ± 2.0%) was higher than SED (79.1 ± 2.5%; p = 0.03) and similar to the young controls (91.4 ± 2.9%). Fifteen metabolites were different with LVAE compared to SED (FDR < 0.05) and correlated with the preservation of physiological function. Plasma spermidine, a polyamine that increases cellular quality control (e.g., autophagy), correlated with all assessed physiological indices. Autophagy (LC3A/B abundance) was higher in LVAE skeletal muscle compared to SED (p < 0.01) and inversely correlated with plasma spermidine (r = - 0.5297; p = 0.054). These findings provide novel insight into the circulating molecular transducers by which LVAE may preserve physiological function with aging.

Keywords:  Aging; Autophagy; Endothelial function; Metabolomics; Physical function; Skeletal muscle; Spermidine

DOI:  https://doi.org/10.1007/s11357-024-01062-x
Proteomes. 2024 Jan 16. pii: 4. [Epub ahead of print]12(1):

How Can Proteomics Help to Elucidate the Pathophysiological Crosstalk in Muscular Dystrophy and Associated Multi-System Dysfunction?

Paul Dowling, Capucine Trollet, Elisa Negroni, Dieter Swandulla, Kay Ohlendieck.

  This perspective article is concerned with the question of how proteomics, which is a core technique of systems biology that is deeply embedded in the multi-omics field of modern bioresearch, can help us better understand the molecular pathogenesis of complex diseases. As an illustrative example of a monogenetic disorder that primarily affects the neuromuscular system but is characterized by a plethora of multi-system pathophysiological alterations, the muscle-wasting disease Duchenne muscular dystrophy was examined. Recent achievements in the field of dystrophinopathy research are described with special reference to the proteome-wide complexity of neuromuscular changes and body-wide alterations/adaptations. Based on a description of the current applications of top-down versus bottom-up proteomic approaches and their technical challenges, future systems biological approaches are outlined. The envisaged holistic and integromic bioanalysis would encompass the integration of diverse omics-type studies including inter- and intra-proteomics as the core disciplines for systematic protein evaluations, with sophisticated biomolecular analyses, including physiology, molecular biology, biochemistry and histochemistry. Integrated proteomic findings promise to be instrumental in improving our detailed knowledge of pathogenic mechanisms and multi-system dysfunction, widening the available biomarker signature of dystrophinopathy for improved diagnostic/prognostic procedures, and advancing the identification of novel therapeutic targets to treat Duchenne muscular dystrophy.

Keywords:  dystrophin; dystrophinopathy; integromics; mass spectrometry; multi-omics; muscle proteomics; myofiber; myology; neuromuscular disease; omics

DOI:  https://doi.org/10.3390/proteomes12010004
Stem Cell Res. 2024 Jan 23. pii: S1873-5061(24)00011-4. [Epub ahead of print]75 103313

Generation of a human ACTA1-tdTomato reporter iPSC line using CRISPR/Cas9 editing.

Peter J Houweling, Vanessa Crossman, Chrystal F Tiong, Chantal A Coles, Rhonda L Taylor, Joshua S Clayton, Alison Graham, Katerina Vlahos, Sara E Howden, Kathryn N North.

We used gene editing to introduce DNA sequences encoding the tdTomato fluorescent protein into the α -skeletal actin 1 (ACTA1) locus to develop an ACTA1-tdTomato induced pluripotent stem cell reporter line for monitoring differentiation of skeletal muscle. This cell line will be used to better understand skeletal muscle maturation and development in vitro as well as provide a useful tool for drug screening and the evaluation of novel therapeutics for the treatment of skeletal muscle disease.

DOI: https://doi.org/10.1016/j.scr.2024.103313
Front Public Health. 2023 ;11 1330131

A mito-centric view on muscle aging and function.

Johannes Burtscher, Barbara Strasser, Martin Burtscher.



Keywords:  aging; diet; exercise; hypoxia; mitochondria; physical function; sarcopenia

DOI:  https://doi.org/10.3389/fpubh.2023.1330131
J Cell Biol. 2024 Feb 05. pii: e202301062. [Epub ahead of print]223(2):

PIGB maintains nuclear lamina organization in skeletal muscle of Drosophila.

Miki Yamamoto-Hino, Masaru Ariura, Masahito Tanaka, Yuka W Iwasaki, Kohei Kawaguchi, Yuta Shimamoto, Satoshi Goto.

The nuclear lamina (NL) plays various roles and participates in nuclear integrity, chromatin organization, and transcriptional regulation. Lamin proteins, the main components of the NL, form a homogeneous meshwork structure under the nuclear envelope. Lamins are essential, but it is unknown whether their homogeneous distribution is important for nuclear function. Here, we found that PIGB, an enzyme involved in glycosylphosphatidylinositol (GPI) synthesis, is responsible for the homogeneous lamin meshwork in Drosophila. Loss of PIGB resulted in heterogeneous distributions of B-type lamin and lamin-binding proteins in larval muscles. These phenotypes were rescued by expression of PIGB lacking GPI synthesis activity. The PIGB mutant exhibited changes in lamina-associated domains that are large heterochromatic genomic regions in the NL, reduction of nuclear stiffness, and deformation of muscle fibers. These results suggest that PIGB maintains the homogeneous meshwork of the NL, which may be essential for chromatin distribution and nuclear mechanical properties.

DOI: https://doi.org/10.1083/jcb.202301062
Am J Physiol Cell Physiol. 2024 Jan 22.

Exploring Frontiers in Musculoskeletal Biology and Bioengineering: Editorial Focus.

Thomas J Hawke, Frank Zaucke.



Keywords:  bone; editorial; engineering; musculoskeletal; skeletal muscle

DOI:  https://doi.org/10.1152/ajpcell.00037.2024
Hum Mol Genet. 2024 Jan 24. pii: ddae007. [Epub ahead of print]

Regional and bilateral MRI and gene signatures in facioscapulohumeral dystrophy: implications for clinical trial design and mechanisms of disease progression.

Chao-Jen Wong, Seth D Friedman, Lauren Snider, Sean R Bennett, Takako I Jones, Peter L Jones, Dennis W W Shaw, Silvia S Blemker, Lara Riem, Olivia DuCharme, Richard J F L Lemmers, Silvère M van der Maarel, Leo H Wang, Rabi Tawil, Jeffrey M Statland, Stephen J Tapscott.

  Identifying the aberrant expression of DUX4 in skeletal muscle as the cause of facioscapulohumeral dystrophy (FSHD) has led to rational therapeutic development and clinical trials. Several studies support the use of MRI characteristics and the expression of DUX4-regulated genes in muscle biopsies as biomarkers of FSHD disease activity and progression. We performed lower-extremity MRI and muscle biopsies in the mid-portion of the tibialis anterior (TA) muscles bilaterally in FSHD subjects and validated our prior reports of the strong association between MRI characteristics and expression of genes regulated by DUX4 and other gene categories associated with FSHD disease activity. We further show that measurements of normalized fat content in the entire TA muscle strongly predict molecular signatures in the mid-portion of the TA, indicating that regional biopsies can accurately measure progression in the whole muscle and providing a strong basis for inclusion of MRI and molecular biomarkers in clinical trial design. An unanticipated finding was the strong correlations of molecular signatures in the bilateral comparisons, including markers of B-cells and other immune cell populations, suggesting that a systemic immune cell infiltration of skeletal muscle might have a role in disease progression.

Keywords:  DUX4; MRI; complement; facioscapulohumeral dystrophy

DOI:  https://doi.org/10.1093/hmg/ddae007
Int J Mol Sci. 2024 Jan 19. pii: 1213. [Epub ahead of print]25(2):

Impact of Exercise Intensity on Cerebral BDNF Levels: Role of FNDC5/Irisin.

Clémence Leger, Aurore Quirié, Alexandre Méloux, Estelle Fontanier, Rémi Chaney, Christelle Basset, Stéphanie Lemaire, Philippe Garnier, Anne Prigent-Tessier.

  The positive effects of physical exercise (EX) are well known to be mediated by cerebral BDNF (brain-derived neurotrophic factor), a neurotrophin involved in learning and memory, the expression of which could be induced by circulating irisin, a peptide derived from Fibronectin type III domain-containing protein 5 (FNDC5) produced by skeletal muscle contraction. While the influence of EX modalities on cerebral BDNF expression was characterized, their effect on muscle FNDC5/Irisin expression and circulating irisin levels remains to be explored. The present study involved Wistar rats divided into four experimental groups: sedentary (SED), low- (40% of maximal aerobic speed, MAS), intermediate- (50% of MAS) and high- (70% of MAS) intensities of treadmill EX (30 min/day, 7 days). Soleus (SOL) versus gastrocnemius (GAS) FNDC5 and hippocampal BDNF expressions were evaluated by Western blotting. Additionally, muscular FNDC5/Irisin localization and serum/hippocampal irisin levels were studied by immunofluorescence and ELISA, respectively. Our findings revealed that (1) serum irisin and hippocampal BDNF levels vary with EX intensity, showing a threshold intensity at 50% of MAS; (2) hippocampal BDNF levels positively correlate with serum irisin but not with hippocampal FNDC5/Irisin; and (3) GAS, in response to EX intensity, overexpresses FNDC5/Irisin in type II muscle fibers. Altogether, peripheral FNDC5/Irisin levels likely explain EX-dependent hippocampal BDNF expression.

Keywords:  BDNF; FNDC5; hippocampus; irisin; muscle fibers; physical exercise intensity

DOI:  https://doi.org/10.3390/ijms25021213
bioRxiv. 2024 Jan 12. pii: 2024.01.10.575040. [Epub ahead of print]

Propofol directly binds and inhibits skeletal muscle ryanodine receptor 1 (RyR1).

Thomas T Joseph, Weiming Bu, Omid Haji-Ghassemi, Yu Seby Chen, Kellie Woll, Paul D Allen, Grace Brannigan, Filip van Petegem, Roderic G Eckenhoff.

As the primary Ca 2+ release channel in skeletal muscle sarcoplasmic reticulum (SR), mutations in the type 1 ryanodine receptor (RyR1) or its binding partners underlie a constellation of muscle disorders, including malignant hyperthermia (MH). In patients with MH mutations, exposure to triggering drugs such as the halogenated volatile anesthetics biases RyR1 to an open state, resulting in uncontrolled Ca 2+ release, sarcomere tension and heat production. Restoration of Ca 2+ into the SR also consumes ATP, generating a further untenable metabolic load. When anesthetizing patients with known MH mutations, the non-triggering intravenous general anesthetic propofol is commonly substituted for triggering anesthetics. Evidence of direct binding of anesthetic agents to RyR1 or its binding partners is scant, and the atomic-level interactions of propofol with RyR1 are entirely unknown. Here, we show that propofol decreases RyR1 opening in heavy SR vesicles and planar lipid bilayers, and that it inhibits activator-induced Ca 2+ release from SR in human skeletal muscle. In addition to confirming direct binding, photoaffinity labeling using m- azipropofol (AziP m ) revealed several putative propofol binding sites on RyR1. Prediction of binding affinity by molecular dynamics simulation suggests that propofol binds at least one of these sites at clinical concentrations. These findings invite the hypothesis that in addition to propofol not triggering MH, it may also be protective against MH by inhibiting induced Ca 2+ flux through RyR1.

DOI: https://doi.org/10.1101/2024.01.10.575040
Front Mol Biosci. 2023 ;10 1308274

The role of non-coding RNAs in muscle aging: regulatory mechanisms and therapeutic potential.

Yeo Jin Shin, Ki-Sun Kwon, Yousin Suh, Kwang-Pyo Lee.

  Muscle aging is a complex physiological process that leads to the progressive decline in muscle mass and function, contributing to debilitating conditions in the elderly such as sarcopenia. In recent years, non-coding RNAs (ncRNAs) have been increasingly recognized as major regulators of muscle aging and related cellular processes. Here, we comprehensively review the emerging role of ncRNAs, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), in the regulation of muscle aging. We also discuss how targeting these ncRNAs can be explored for the development of novel interventions to combat age-related muscle decline. The insights provided in this review offer a promising avenue for future research and therapeutic strategies aimed at improving muscle health during aging.

Keywords:  aging; circRNA; lncRNA; miRNA; ncRNA; skeletal muscle

DOI:  https://doi.org/10.3389/fmolb.2023.1308274
Methods Mol Biol. 2024 ;2766 25-30

Denervation-Induced Sarcopenia Model.

Erika Takemasa, Shuang Liu.

  Rheumatoid arthritis (RA) is an important risk factor for sarcopenia. Physical inactivity, systemic inflammatory factors, and medication directly or indirectly induce skeletal muscle loss in RA patients. The sarcopenia-induced systemic or local proinflammatory microenvironment also contributes to the onset and progression of autoimmune disease. Accumulated evidence suggests the importance of treatment and management of sarcopenia in patients with RA to improve their long-term prognosis. To elucidate the relationship between skeletal muscle and systemic immune homeostasis, a denervation-induced skeletal muscle-losing mouse model is introduced in this chapter. By developing local amyotrophy in the sciatic nerve-dominant area in a RA model, the underlying mechanism of sarcopenia in RA could be assessed. Also, an examination of the efficacy of anti-rheumatic regents on sarcopenia and the influence of sarcopenia management on RA improvement is also achievable.

Keywords:  Autoimmune disease; Immune homeostasis; Sarcopenia; Sciatic nerve; Skeletal muscle

DOI:  https://doi.org/10.1007/978-1-0716-3682-4_4
Nutrients. 2024 Jan 18. pii: 286. [Epub ahead of print]16(2):

Sucrose-Enriched and Carbohydrate-Free High-Fat Diets Distinctly Affect Substrate Metabolism in Oxidative and Glycolytic Muscles of Rats.

Daniel Da Eira, Shailee Jani, Mateja Stefanovic, Rolando B Ceddia.

  Skeletal muscle substrate preference for fuel is largely influenced by dietary macronutrient availability. The abundance of dietary carbohydrates promotes the utilization of glucose as a substrate for energy production, whereas an abundant dietary fat supply elevates rates of fatty acid (FA) oxidation. The objective of this study was to determine whether an obesogenic, high-fat, sucrose-enriched (HFS) diet or a carbohydrate-free ketogenic diet (KD) exert distinct effects on fat, glucose, and ketone metabolism in oxidative and glycolytic skeletal muscles. Male Wistar rats were fed either a HFS diet or a KD for 16 weeks. Subsequently, the soleus (Sol), extensor digitorum longus (EDL), and epitrochlearis (Epit) muscles were extracted to measure palmitate oxidation, insulin-stimulated glucose metabolism, and markers of mitochondrial biogenesis, ketolytic capacity, and cataplerotic and anaplerotic machinery. Sol, EDL, and Epit muscles from KD-fed rats preserved their ability to elevate glycogen synthesis and lactate production in response to insulin, whereas all muscles from rats fed with the HFS diet displayed blunted responses to insulin. The maintenance of metabolic flexibility with the KD was accompanied by muscle-fiber-type-specific adaptive responses. This was characterized by the Sol muscle in KD-fed rats enhancing mitochondrial biogenesis and ketolytic capacity without elevating its rates of FA oxidation in comparison with that in HFS feeding. Conversely, in the Epit muscle, rates of FA oxidation were increased, whereas the ketolytic capacity was markedly reduced by the KD in comparison with that by HFS feeding. In the EDL muscle, the KD also increased rates of FA oxidation, although it did so without altering its ketolytic capacity when compared to HFS feeding. In conclusion, even though obesogenic and ketogenic diets have elevated contents of fat and alter whole-body substrate partitioning, these two dietary interventions are associated with opposite outcomes with respect to skeletal muscle metabolic flexibility.

Keywords:  ACAT1; OXCT; PGC-1α; TFAM; anaplerosis; insulin resistance; ketogenic diet; ketolysis

DOI:  https://doi.org/10.3390/nu16020286
Front Physiol. 2023 ;14 1322677

Active vitamin D increases myogenic differentiation in C2C12 cells via a vitamin D response element on the myogenin promoter.

Kathryn H Alliband, Tim Parr, Preeti H Jethwa, John M Brameld.

  Background: Skeletal muscle development during embryogenesis depends on proliferation of myoblasts followed by differentiation into myotubes/multinucleated myofibers. Vitamin D (VD) has been shown to affect these processes, but there is conflicting evidence within the current literature on the exact nature of these effects due to a lack of time course data. With 20%-40% of pregnant women worldwide being VD deficient, it is crucial that a clearer understanding of the impact of VD on myogenesis is gained. Methods: A detailed 8-day differentiation time course was used where C2C12 cells were differentiated in control media (2% horse serum) or with different concentrations of active VD, 1,25 (OH)2D3 (10-13 M, 10-11 M, 10-9 M or 10-7 M), and measurements were taken at 6 time points. DNA, creatine kinase and protein assays were carried out as well as quantitative PCR to determine expression of Myf5, MyoD, myogenin, MHC I, and MHC neonatal, MHC embryonic, MHC IIa, MHC IIx, and MHC IIb mRNAs. Transfections were carried out using one vector containing the myogenin promoter and another containing the same promoter with a 3 base mutation within a putative vitamin D response element (VDRE) to determine effects of 1,25 (OH)2D3 on myogenin transcription. Finally, a ChIP assay was performed to determine whether the VD receptor (VDR) binds to the putative VDRE. Results: 1,25(OH)2D3 caused an inhibition of proliferation and an increase in differentiation in C2C12 cells. Myf5, myogenin, MHC I, and MHC neonatal, MHC embryonic, MHC IIa, MHC IIx, and MHC IIb expression were all increased by 1,25(OH)2D3. Myotube size was also increased by VD. When the putative VDRE on the myogenin promoter was mutated, the increase in expression by VD was lost. ChIP analysis revealed that the VDR does bind to the putative VDRE on the myogenin promoter. Conclusion: Active VD directly increases myogenin transcription via a functional VDRE on the myogenin promoter, resulting in increased myogenic differentiation, increased expression of both the early and late MHC isoforms, and also increased myotube size. These results highlight the importance of VD status during pregnancy for normal myogenesis to occur, but further in vivo work is needed.

Keywords:  differentiation; myogenesis; myogenin; vitamin D; vitamin D receptor; vitamin D response element

DOI:  https://doi.org/10.3389/fphys.2023.1322677