bims-moremu 2021-07-11 papers

bims-moremu

Biomed News

on Molecular regulators of muscle mass

Issue of 2021‒07‒11
thirty-one papers selected by
Anna Vainshtein
Craft Science Inc.

mRNP granule proteins Fmrp and Dcp1a differentially regulate mRNP complexes to contribute to control of muscle stem cell quiescence and activation.
Exercise Counterbalances Rho/ROCK2 Signaling Impairment in the Skeletal Muscle and Ameliorates Insulin Sensitivity in Obese Mice.
p21-Activated Kinase 1 Is Permissive for the Skeletal Muscle Hypertrophy Induced by Myostatin Inhibition.
Endogenous Galectin-3 is required for skeletal muscle repair.
Lipocalin 2 increases after high-intensity exercise in humans and influences muscle gene expression and differentiation in mice.
Suppression of MyoD induces spontaneous adipogenesis in skeletal muscle progenitor cell culture.
Amiloride ameliorates muscle wasting in cancer cachexia through inhibiting tumor-derived exosome release.
Declined expressions of vast mitochondria-related genes represented by CYCS and transcription factor ESRRA in skeletal muscle aging.
Lipophorin receptor 1 (LpR1) in Drosophila muscle influences life span by regulating mitochondrial aging.
Biophysical matrix cues from the regenerating niche direct muscle stem cell fate in engineered microenvironments.
Valproic acid stimulates myogenesis in pluripotent stem cell-derived mesodermal progenitors in a NOTCH-dependent manner.
The effects of exercise training versus intensive insulin treatment on skeletal muscle fibre content in type 1 diabetes mellitus rodents.
Chronic intermittent hypoxia aggravates skeletal muscle aging by down-regulating Klc1/grx1 expression via Wnt/β-catenin pathway.
Spinal Muscular Atrophy autophagy profile is tissue-dependent: differential regulation between muscle and motoneurons.
Exercise Training Attenuates Ubiquitin-Proteasome Pathway and Increases the Genes Related to Autophagy on the Skeletal Muscle of Patients With Inflammatory Myopathies.
3D Anisotropic Conductive Fibers Electrically Stimulated Myogenesis.
Distribution of dietary protein intake in daily meals influences skeletal muscle hypertrophy via the muscle clock.
14-Deoxy-11,12-Didehydroandrographolide Ameliorates Glucose Intolerance Enhancing the LKB1/AMPK[Formula: see text]/TBC1D1/GLUT4 Signaling Pathway and Inducing GLUT4 Expression in Myotubes and Skeletal Muscle of Obese Mice.
Skeletal muscle proteomes reveal downregulation of mitochondrial proteins in transition from prediabetes into type 2 diabetes.
Oxidative phenotype induced by aerobic physical training prevents the obesity-linked insulin resistance without changes in gastrocnemius muscle ACE2-Angiotensin(1-7)-Mas axis.
Receptor-Mediated Muscle Homeostasis as a Target for Sarcopenia Therapeutics.
Neuroprotective effects of exercise on the aging human neuromuscular system.
Analysis of proteostasis during aging with western blot of detergent-soluble and insoluble protein fractions.
Proprioception revisited: where do we stand?
Muscles proteome analysis; irisin administration mimics some molecular effects of exercise in quadriceps muscle.
Matrisome, innervation and oxidative metabolism affected in older compared with younger males with similar physical activity.
Use of EP3533-Enhanced Magnetic Resonance Imaging as a Measure of Disease Progression in Skeletal Muscle of mdx Mice.
Nrf2 activation induces mitophagy and reverses Parkin/Pink1 knock down-mediated neuronal and muscle degeneration phenotypes.
Investigating Transcriptional Dynamics Changes and Time-Dependent Marker Gene Expression in the Early Period After Skeletal Muscle Injury in Rats.
Combining multiomics and drug perturbation profiles to identify muscle-specific treatments for spinal muscular atrophy.
Redox interactions of immune cells and muscle in the regulation of exercise-induced pain and analgesia: implications on the modulation of muscle nociceptor sensory neurons.

Skelet Muscle. 2021 Jul 08. 11(1): 18

mRNP granule proteins Fmrp and Dcp1a differentially regulate mRNP complexes to contribute to control of muscle stem cell quiescence and activation.

Nainita Roy, Swetha Sundar, Malini Pillai, Farah Patell-Socha, Sravya Ganesh, Ajoy Aloysius, Mohammed Rumman, Hardik Gala, Simon M Hughes, Peter S Zammit, Jyotsna Dhawan.

  BACKGROUND: During skeletal muscle regeneration, satellite stem cells use distinct pathways to repair damaged myofibers or to self-renew by returning to quiescence. Cellular/mitotic quiescence employs mechanisms that promote a poised or primed state, including altered RNA turnover and translational repression. Here, we investigate the role of mRNP granule proteins Fragile X Mental Retardation Protein (Fmrp) and Decapping protein 1a (Dcp1a) in muscle stem cell quiescence and differentiation.METHODS: Using isolated single muscle fibers from adult mice, we established differential enrichment of mRNP granule proteins including Fmrp and Dcp1a in muscle stem cells vs. myofibers. We investigated muscle tissue homeostasis in adult Fmr1-/- mice, analyzing myofiber cross-sectional area in vivo and satellite cell proliferation ex vivo. We explored the molecular mechanisms of Dcp1a and Fmrp function in quiescence, proliferation and differentiation in a C2C12 culture model. Here, we used polysome profiling, imaging and RNA/protein expression analysis to establish the abundance and assembly status of mRNP granule proteins in different cellular states, and the phenotype of knockdown cells.
RESULTS: Quiescent muscle satellite cells are enriched for puncta containing the translational repressor Fmrp, but not the mRNA decay factor Dcp1a. MuSC isolated from Fmr1-/- mice exhibit defective proliferation, and mature myofibers show reduced cross-sectional area, suggesting a role for Fmrp in muscle homeostasis. Expression and organization of Fmrp and Dcp1a varies during primary MuSC activation on myofibers, with Fmrp puncta prominent in quiescence, but Dcp1a puncta appearing during activation/proliferation. This reciprocal expression of Fmrp and Dcp1a puncta is recapitulated in a C2C12 culture model of quiescence and activation: consistent with its role as a translational repressor, Fmrp is enriched in non-translating mRNP complexes abundant in quiescent myoblasts; Dcp1a puncta are lost in quiescence, suggesting stabilized and repressed transcripts. The function of each protein differs during proliferation; whereas Fmrp knockdown led to decreased proliferation and lower cyclin expression, Dcp1a knockdown led to increased cell proliferation and higher cyclin expression. However, knockdown of either Fmrp or Dcp1a led to compromised differentiation. We also observed cross-regulation of decay versus storage mRNP granules; knockdown of Fmrp enhances accumulation of Dcp1a puncta, whereas knockdown of Dcp1a leads to increased Fmrp in puncta.
CONCLUSIONS: Taken together, our results provide evidence that the balance of mRNA turnover versus utilization is specific for distinct cellular states.

Keywords:  Dcp1a; Fmr1 knockout; Fmrp; G0; Muscle stem cell; Myoblast; Quiescence; Skeletal muscle; Translational control; mRNA decay; mRNP granule

DOI:  https://doi.org/10.1186/s13395-021-00270-9
Front Immunol. 2021 ;12 702025

Exercise Counterbalances Rho/ROCK2 Signaling Impairment in the Skeletal Muscle and Ameliorates Insulin Sensitivity in Obese Mice.

Vitor R Muñoz, Rafael C Gaspar, Matheus B Severino, Ana P A Macêdo, Fernando M Simabuco, Eduardo R Ropelle, Dennys E Cintra, Adelino S R da Silva, Young-Bum Kim, José Rodrigo Pauli.

  Physical exercise is considered a fundamental strategy in improving insulin sensitivity and glucose uptake in skeletal muscle. However, the molecular mechanisms underlying this regulation, primarily on skeletal muscle glucose uptake, are not fully understood. Recent evidence has shown that Rho-kinase (ROCK) isoforms play a pivotal role in regulating skeletal muscle glucose uptake and systemic glucose homeostasis. The current study evaluated the effect of physical exercise on ROCK2 signaling in skeletal muscle of insulin-resistant obese animals. Physiological (ITT) and molecular analysis (immunoblotting, and RT-qPCR) were performed. The contents of RhoA and ROCK2 protein were decreased in skeletal muscle of obese mice compared to control mice but were restored to normal levels in response to physical exercise. The exercised animals also showed higher phosphorylation of insulin receptor substrate 1 (IRS1 Serine 632/635) and protein kinase B (Akt) in the skeletal muscle. However, phosphatase and tensin homolog (PTEN) and protein-tyrosine phosphatase-1B (PTP-1B), both inhibitory regulators for insulin action, were increased in obesity but decreased after exercise. The impact of ROCK2 action on muscle insulin signaling is further underscored by the fact that impaired IRS1 and Akt phosphorylation caused by palmitate in C2C12 myotubes was entirely restored by ROCK2 overexpression. These results suggest that the exercise-induced upregulation of RhoA-ROCK2 signaling in skeletal muscle is associated with increased systemic insulin sensitivity in obese mice and further implicate that muscle ROCK2 could be a potential target for treating obesity-linked metabolic disorders.

Keywords:  Rho-kinase (ROCK); exercise; insulin sensitivity; obesity; skeletal muscle

DOI:  https://doi.org/10.3389/fimmu.2021.702025
Front Physiol. 2021 ;12 677746

p21-Activated Kinase 1 Is Permissive for the Skeletal Muscle Hypertrophy Induced by Myostatin Inhibition.

Caroline Barbé, Audrey Loumaye, Pascale Lause, Olli Ritvos, Jean-Paul Thissen.

  Skeletal muscle, the most abundant tissue in the body, plays vital roles in locomotion and metabolism. Understanding the cellular processes that govern regulation of muscle mass and function represents an essential step in the development of therapeutic strategies for muscular disorders. Myostatin, a member of the TGF-β family, has been identified as a negative regulator of muscle development. Indeed, its inhibition induces an extensive skeletal muscle hypertrophy requiring the activation of Smad 1/5/8 and the Insulin/IGF-I signaling pathway, but whether other molecular mechanisms are involved in this process remains to be determined. Using transcriptomic data from various Myostatin inhibition models, we identified Pak1 as a potential mediator of Myostatin action on skeletal muscle mass. Our results show that muscle PAK1 levels are systematically increased in response to Myostatin inhibition, parallel to skeletal muscle mass, regardless of the Myostatin inhibition model. Using Pak1 knockout mice, we investigated the role of Pak1 in the skeletal muscle hypertrophy induced by different approaches of Myostatin inhibition. Our findings show that Pak1 deletion does not impede the skeletal muscle hypertrophy magnitude in response to Myostatin inhibition. Therefore, Pak1 is permissive for the skeletal muscle mass increase caused by Myostatin inhibition.

Keywords:  PAK1; follistatin; myostatin; sActRIIB; skeletal muscle hypertrophy

DOI:  https://doi.org/10.3389/fphys.2021.677746
Glycobiology. 2021 Jul 05. pii: cwab071. [Epub ahead of print]

Endogenous Galectin-3 is required for skeletal muscle repair.

Daniel Giuliano Cerri, Lilian Cataldi Rodrigues, Vani Maria Alves, Juliano Machado, Víctor Alexandre Félix Bastos, Isis Carmo Kettelhut, Luciane Carla Alberici, Maria Cristina R Costa, Sean R Stowell, Richard D Cummings, Marcelo Dias-Baruffi.

  Skeletal muscle has the intrinsic ability to self-repair through a multifactorial process, but many aspects of its cellular and molecular mechanisms are not fully understood. There is increasing evidence that some members of the mammalian β-galactoside-binding protein family (galectins) are involved in the muscular repair process (MRP), including galectin-3 (Gal-3). However, there are many questions about the role of this protein on muscle self-repair. Here, we demonstrate that endogenous Gal-3 is required for: i) muscle repair in vivo using a chloride-barium myolesion mouse model, and ii) mouse primary myoblasts myogenic programming. Injured muscle from Gal-3 knockout mice (GAL3KO) showed persistent inflammation associated with compromised muscle repair and the formation of fibrotic tissue on the lesion site. In GAL3KO mice, osteopontin expression remained high even after 7 and 14 days of the myolesion, while MyoD and myogenin had decreased their expression. In GAL3KO mouse primary myoblast cell culture, Pax7 detection seems to sustain even when cells are stimulated to differentiation and MyoD expression is drastically reduced. The detection and temporal expression levels of these transcriptional factors appear to be altered in Gal-3-deficient myoblast. Gal-3 expression in WT states, both in vivo and in vitro, in sarcoplasm/cytoplasm and myonuclei; as differentiation proceeds, Gal-3 expression is drastically reduced, and its location is confined to the sarcolemma/plasma cell membrane. We also observed a change in the temporal-spatial profile of Gal-3 expression and muscle transcription factors levels during the myolesion. Overall, these results demonstrate that endogenous Gal-3 is required for the skeletal muscle repair process.

Keywords:  Galectin-3; Muscle repair; Myoblast; Myolesion; Myotubes

DOI:  https://doi.org/10.1093/glycob/cwab071
J Cell Physiol. 2021 Jul 05.

Lipocalin 2 increases after high-intensity exercise in humans and influences muscle gene expression and differentiation in mice.

Marco Ponzetti, Federica Aielli, Argia Ucci, Alfredo Cappariello, Giovanni Lombardi, Anna Teti, Nadia Rucci.

  Lipocalin 2 (LCN2) is an adipokine that accomplishes several functions in diverse organs. However, its importance in muscle and physical exercise is currently unknown. We observed that following acute high-intensity exercise ("Gran Sasso d'Italia" vertical run), LCN2 serum levels were increased. The Wnt pathway antagonist, DKK1, was also increased after the run, positively correlating with LCN2, and the same was found for the cytokine Interleukin 6. We, therefore, investigated the involvement of LCN2 in muscle physiology employing an Lcn2 global knockout (Lcn2-/- ) mouse model. Lcn2-/- mice presented with smaller muscle fibres but normal muscle performance (grip strength metre) and muscle weight. At variance with wild type (WT) mice, the inflammatory cytokine Interleukin 6 was undetectable in Lcn2-/- mice at all ages. Intriguingly, Lcn2-/- mice did not lose gastrocnemius and quadriceps muscle mass and muscle performance following hindlimb suspension, while at variance with WT, they lose soleus muscle mass. In vitro, LCN2 treatment reduced the myogenic differentiation of C2C12 and primary mouse myoblasts and influenced their gene expression. Treating myoblasts with LCN2 reduced myogenesis, suggesting that LCN2 may negatively affect muscle physiology when upregulated following high-intensity exercise.

Keywords:  adipokines; bone; exercise; lipocalin 2; muscle; myogenesis

DOI:  https://doi.org/10.1002/jcp.30501
Anim Sci J. 2021 Dec;92(1): e13573

Suppression of MyoD induces spontaneous adipogenesis in skeletal muscle progenitor cell culture.

Keitaro Yamanouchi, Katsuyuki Nakamura, Shiho Takeuchi, Tohru Hosoyama, Takashi Matsuwaki, Masugi Nishihara.

  The degree of intramuscular adipose tissue accumulation is one of the factors affecting meat quality. Accumulation of adipocytes is also observed under the pathological condition of skeletal muscle such as muscular dystrophy and sarcopenia. The origin of adipocytes seen in skeletal muscle is mesenchymal progenitor cells that can give rise to both adipocytes and fibroblasts. In the present study, we demonstrated that siRNA-mediated suppression of MyoD expression in rat skeletal muscle progenitor cell culture, which comprises both myogenic satellite cells and mesenchymal progenitor cells, resulted in diminished myotube formation and an unexpected spontaneous appearance of white adipocytes. Suppressing myomaker expression also resulted in complete absence of myotube formation without reducing MyoD expression, but no adipogenesis was seen in this scenario, indicating that decline in MyoD expression rather than decreased myotube formation is necessary to induce adipogenesis. In addition, spontaneous adipogenesis induced by suppressing MyoD expression in culture was inhibited by the conditioned medium from control culture, indicating that anti-adipogenic factor(s) are secreted from MyoD-positive myogenic cells. These results indicate the presence of regulatory mechanism on adipogenesis by myogenic cells.

Keywords:  MyoD; adipogenesis; mesenchymal progenitor cells; myogenesis; satellite cells

DOI:  https://doi.org/10.1111/asj.13573
Skelet Muscle. 2021 Jul 06. 11(1): 17

Amiloride ameliorates muscle wasting in cancer cachexia through inhibiting tumor-derived exosome release.

Lin Zhou, Tong Zhang, Wei Shao, Ruohan Lu, Lin Wang, Haisheng Liu, Bin Jiang, Shiqin Li, Huiqin Zhuo, Suheng Wang, Qinxi Li, Caihua Huang, Donghai Lin.

  BACKGROUND: Cancer cachexia (CAC) reduces patient survival and quality of life. Developments of efficient therapeutic strategies are required for the CAC treatments. This long-term process could be shortened by the drug-repositioning approach which exploits old drugs approved for non-cachexia disease. Amiloride, a diuretic drug, is clinically used for treatments of hypertension and edema due to heart failure. Here, we explored the effects of the amiloride treatment for ameliorating muscle wasting in murine models of cancer cachexia.METHODS: The CT26 and LLC tumor cells were subcutaneously injected into mice to induce colon cancer cachexia and lung cancer cachexia, respectively. Amiloride was intraperitoneally injected daily once tumors were formed. Cachexia features of the CT26 model and the LLC model were separately characterized by phenotypic, histopathologic and biochemical analyses. Plasma exosomes and muscle atrophy-related proteins were quantitatively analyzed. Integrative NMR-based metabolomic and transcriptomic analyses were conducted to identify significantly altered metabolic pathways and distinctly changed metabolism-related biological processes in gastrocnemius.
RESULTS: The CT26 and LLC cachexia models displayed prominent cachexia features including decreases in body weight, skeletal muscle, adipose tissue, and muscle strength. The amiloride treatment in tumor-bearing mice distinctly alleviated muscle atrophy and relieved cachexia-related features without affecting tumor growth. Both the CT26 and LLC cachexia mice showed increased plasma exosome densities which were largely derived from tumors. Significantly, the amiloride treatment inhibited tumor-derived exosome release, which did not obviously affect exosome secretion from non-neoplastic tissues or induce observable systemic toxicities in normal healthy mice. Integrative-omics revealed significant metabolic impairments in cachectic gastrocnemius, including promoted muscular catabolism, inhibited muscular protein synthesis, blocked glycolysis, and impeded ketone body oxidation. The amiloride treatment evidently improved the metabolic impairments in cachectic gastrocnemius.
CONCLUSIONS: Amiloride ameliorates cachectic muscle wasting and alleviates cancer cachexia progression through inhibiting tumor-derived exosome release. Our results are beneficial to understanding the underlying molecular mechanisms, shedding light on the potentials of amiloride in cachexia therapy.

Keywords:  Amiloride; Cancer cachexia; Exosome; Exosome-release inhibition; Muscle wasting

DOI:  https://doi.org/10.1186/s13395-021-00274-5
Bioengineered. 2021 Dec;12(1): 3485-3502

Declined expressions of vast mitochondria-related genes represented by CYCS and transcription factor ESRRA in skeletal muscle aging.

Jingbao Kan, Yifang Hu, Yaoqi Ge, WenSong Zhang, Shan Lu, Cuiping Zhao, Rihua Zhang, Yun Liu.

  Age-related skeletal muscle deterioration (sarcopenia) has a significant effect on the elderly's health and quality of life, but the molecular and gene regulatory mechanisms remain largely unknown. It is necessary to identify the candidate genes related to skeletal muscle aging and prospective therapeutic targets for effective treatments. The age-line-related genes (ALRGs) and age-line-related transcripts (ALRTs) were investigated using the gene expression profiles of GSE47881 and GSE118825 from the Gene Expression Omnibus (GEO) database. The protein-protein interaction (PPI) networks were performed to identify the key molecules with Cytoscape, and Gene Set Enrichment Analysis (GSEA) was used to clarify the potential molecular functions. Two hub molecules were finally obtained and verified with quantitative real-time PCR (qRT-PCR). The results showed that the expression of mitochondria genes involved in mitochondrial electron transport, complex assembly of the respiratory chain, tricarboxylic acid cycle, oxidative phosphorylation, and ATP synthesis were down-regulated in skeletal muscle with aging. We further identified a primary hub gene of CYCS (Cytochrome C) and a key transcription factor of ESRRA (Estrogen-related Receptor Alpha) to be associated closely with skeletal muscle aging. PCR analysis confirmed the expressions of CYCS and ESRRA in gastrocnemius muscles of mice of different ages were significantly different, and decreased gradually with age. In conclusion, the main cause of skeletal muscle aging may be the systematically reduced expression of mitochondrial functional genes. The CYCS and ESRRA may play significant roles in the progression of skeletal muscle aging and serve as potential biomarkers for future diagnosis and treatment.

Keywords:  CYCS; ESRRA; Skeletal muscle aging; gene expression; mitochondria

DOI:  https://doi.org/10.1080/21655979.2021.1948951
Biochem Biophys Res Commun. 2021 Jun 29. pii: S0006-291X(21)01002-0. [Epub ahead of print]568 95-102

Lipophorin receptor 1 (LpR1) in Drosophila muscle influences life span by regulating mitochondrial aging.

Ae-Kyeong Kim, Dae-Woo Kwon, Eunbyul Yeom, Kwang-Pyo Lee, Ki-Sun Kwon, Kweon Yu, Kyu-Sun Lee.

  Sarcopenia is a syndrome characterized by progressive loss of muscle mass and function during aging. Although mitochondrial dysfunction and related metabolic defects precede age-related changes in muscle, their contributions to muscle aging are still not well known. In this study, we used a Drosophila model to investigate the role of lipophorin receptors (LpRs), a Drosophila homologue of the mammalian very low-density lipoprotein receptor (VLDLR), in mitochondrial dynamics and muscle aging. Muscle-specific knockdown of LpR1 or LpR2 resulted in mitochondrial dysfunction and reduced proteostasis, which contributed to muscle aging. Activation of AMP-activated protein kinase (AMPK) ameliorated muscle dysfunction induced by LpR1 knockdown. These results suggest that LpR1/VLDLR is a novel key target that modulates age-dependent lipid remodeling and muscle homeostasis.

Keywords:  Aging; Drosophila model; Lipoprotein receptor; Mitochondria; Sarcopenia

DOI:  https://doi.org/10.1016/j.bbrc.2021.06.080
Biomaterials. 2021 Jun 14. pii: S0142-9612(21)00329-X. [Epub ahead of print]275 120973

Biophysical matrix cues from the regenerating niche direct muscle stem cell fate in engineered microenvironments.

Christopher M Madl, Iris A Flaig, Colin A Holbrook, Yu Xin Wang, Helen M Blau.

  Skeletal muscle stem cells (MuSCs) are essential for efficacious muscle repair, making MuSCs promising therapeutic targets for tissue engineering and regenerative medicine. MuSCs are presented with a diverse and temporally defined set of cues from their microenvironment during regeneration that direct stem cell expansion, differentiation, and return to quiescence. Understanding the complex interplay among these biophysical and biochemical cues is necessary to develop therapies targeting or employing MuSCs. To probe the role of mechanical cues presented by the extracellular matrix, we leverage chemically defined hydrogel substrates with controllable stiffness and adhesive ligand composition to characterize the MuSC response to matrix cues presented during early and late phases of regeneration. We demonstrate that relatively soft hydrogels recapitulating healthy muscle stiffness promote MuSC activation and expansion, while relatively stiff hydrogels impair MuSC proliferation and arrest myogenic progression. These effects are seen on soft and stiff hydrogels presenting laminin-111 and exacerbated on hydrogels presenting RGD adhesive peptides. Soluble factors present in the MuSC niche during different phases of regeneration, prostaglandin E2 and oncostatin M, synergize with matrix-presented cues to enhance stem cell expansion on soft substrates and block myogenic progression on stiff substrates. To determine if temporally varied matrix stiffness reminiscent of the regenerating microenvironment alters MuSC fate, we developed a photoresponsive hydrogel system with accelerated reaction kinetics that can be rapidly softened on demand. MuSCs cultured on these materials revealed that the cellular response to a stiff microenvironment is fixed within the first three days of culture, as subsequent softening back to a healthy stiffness did not rescue MuSC proliferation or myogenic progression. These results highlight the importance of temporally controlled biophysical and biochemical cues in regulating MuSC fate that can be harnessed to improve regenerative medicine approaches to restore skeletal muscle tissue.

Keywords:  Bioengineering; Extracellular matrix; Hydrogels; Mechanosensing; Muscle stem cells; Stem cell niche

DOI:  https://doi.org/10.1016/j.biomaterials.2021.120973
Cell Death Dis. 2021 Jul 05. 12(7): 677

Valproic acid stimulates myogenesis in pluripotent stem cell-derived mesodermal progenitors in a NOTCH-dependent manner.

Natacha Breuls, Nefele Giarratana, Laura Yedigaryan, Gabriel Miró Garrido, Paolo Carai, Stephane Heymans, Adrian Ranga, Christophe Deroose, Maurilio Sampaolesi.

Muscular dystrophies are debilitating neuromuscular disorders for which no cure exists. As this disorder affects both cardiac and skeletal muscle, patients would benefit from a cellular therapy that can simultaneously regenerate both tissues. The current protocol to derive bipotent mesodermal progenitors which can differentiate into cardiac and skeletal muscle relies on the spontaneous formation of embryoid bodies, thereby hampering further clinical translation. Additionally, as skeletal muscle is the largest organ in the human body, a high myogenic potential is necessary for successful regeneration. Here, we have optimized a protocol to generate chemically defined human induced pluripotent stem cell-derived mesodermal progenitors (cdMiPs). We demonstrate that these cells contribute to myotube formation and differentiate into cardiomyocytes, both in vitro and in vivo. Furthermore, the addition of valproic acid, a clinically approved small molecule, increases the potential of the cdMiPs to contribute to myotube formation that can be prevented by NOTCH signaling inhibitors. Moreover, valproic acid pre-treated cdMiPs injected in dystrophic muscles increase physical strength and ameliorate the functional performances of transplanted mice. Taken together, these results constitute a novel approach to generate mesodermal progenitors with enhanced myogenic potential using clinically approved reagents.

DOI: https://doi.org/10.1038/s41419-021-03936-w
Lipids Health Dis. 2021 Jul 06. 20(1): 64

The effects of exercise training versus intensive insulin treatment on skeletal muscle fibre content in type 1 diabetes mellitus rodents.

David P McBey, Michelle Dotzert, C W J Melling.

  BACKGROUND: Intensive-insulin treatment (IIT) strategy for patients with type 1 diabetes mellitus (T1DM) has been associated with sedentary behaviour and the development of insulin resistance. Exercising patients with T1DM often utilize a conventional insulin treatment (CIT) strategy leading to increased insulin sensitivity through improved intramyocellular lipid (IMCL) content. It is unclear how these exercise-related metabolic adaptations in response to exercise training relate to individual fibre-type transitions, and whether these alterations are evident between different insulin strategies (CIT vs. IIT).PURPOSE: This study examined glycogen and fat content in skeletal muscle fibres of diabetic rats following exercise-training.
METHODS: Male Sprague-Dawley rats were divided into four groups: Control-Sedentary, CIT- and IIT-treated diabetic sedentary, and CIT-exercised trained (aerobic/resistance; DARE). After 12 weeks, muscle-fibre lipids and glycogen were compared through immunohistochemical analysis.
RESULTS: The primary findings were that both IIT and DARE led to significant increases in type I fibres when compared to CIT, while DARE led to significantly increased lipid content in type I fibres compared to IIT.
CONCLUSIONS: These findings indicate that alterations in lipid content with insulin treatment and DARE are primarily evident in type I fibres, suggesting that muscle lipotoxicity in type 1 diabetes is muscle fibre-type dependant.

Keywords:  Exercise; Insulin treatment; Intramyocellular lipids; Muscle glycogen; Skeletal muscle fibre; Type 1 diabetes mellitus

DOI:  https://doi.org/10.1186/s12944-021-01494-w
Arch Gerontol Geriatr. 2021 Jun 22. pii: S0167-4943(21)00123-0. [Epub ahead of print]96 104460

Chronic intermittent hypoxia aggravates skeletal muscle aging by down-regulating Klc1/grx1 expression via Wnt/β-catenin pathway.

Hua Guo, Yunyun Zhang, Tingting Han, Xiaochuan Cui, Xiang Lu.

  OBJECTIVE: Sleep breathing disorder may affect skeletal muscle decline in the elderly, but the mechanism is not clear. Therefore, this study explores the mechanism of skeletal muscle aging in chronic intermittent hypoxia (CIH) rats.METHODS: In vitro and in vivo CIH models were constructed in L6 cells and SD rats by treating chronic intermittent hypoxia. Pathological changes of skeletal muscle in vivo were measured by hematoxylin-eosin (HE) staining. Cell proliferation and apoptosis were detected by CCK-8 and Flow cytometer, respectively. The expression of KLC1/GRX1 and the proteins related to the Wnt/β-catenin pathway were measured by qRT-PCR and western blot.
RESULTS: CIH model was successfully established induced by chronic intermittent hypoxia with lower skeletal muscle index (SMI), increased inward migration of muscle fiber cell nucleus, and muscle cells' distance. The results showed that Wnt/β-catenin signalling was activatedin both L6 cells and CIH rats' model. KLC1 and GRX1 were significantly downregulated in the CIH model. Loss of function showed that downregulation of KLC1 promoted L6 cell and skeletal muscle aging in vitro and in vivo, respectively.
CONCLUSION: Our results demonstrated that CIH aggravated skeletal muscle aging by down-regulating KLC1/GRX1 expression via the Wnt/β-catenin pathway.

Keywords:  Chronic Intermittent Hypoxia; Klc1/Grx1; Skeletal Muscle Aging; Wnt/Β-Catenin Pathway

DOI:  https://doi.org/10.1016/j.archger.2021.104460
Acta Neuropathol Commun. 2021 Jul 03. 9(1): 122

Spinal Muscular Atrophy autophagy profile is tissue-dependent: differential regulation between muscle and motoneurons.

Alba Sansa, Ivan Hidalgo, Maria P Miralles, Sandra de la Fuente, M Jose Perez-Garcia, Francina Munell, Rosa M Soler, Ana Garcera.

  Spinal muscular atrophy (SMA) is a neuromuscular genetic disease caused by reduced survival motor neuron (SMN) protein. SMN is ubiquitous and deficient levels cause spinal cord motoneurons (MNs) degeneration and muscle atrophy. Nevertheless, the mechanism by which SMN reduction in muscle contributes to SMA disease is not fully understood. Therefore, studies evaluating atrophy mechanisms in SMA muscles will contribute to strengthening current knowledge of the pathology. Here we propose to evaluate autophagy in SMA muscle, a pathway altered in myotube atrophy. We analized autophagy proteins and mTOR in muscle biopsies, fibroblasts, and lymphoblast cell lines from SMA patients and in gastrocnemius muscles from a severe SMA mouse model. Human MNs differentiated from SMA and unaffected control iPSCs were also included in the analysis of the autophagy. Muscle biopsies, fibroblasts, and lymphoblast cell lines from SMA patients showed reduction of the autophagy marker LC3-II. In SMA mouse gastrocnemius, we observed lower levels of LC3-II, Beclin 1, and p62/SQSTM1 proteins at pre-symptomatic stage. mTOR phosphorylation at Ser2448 was decreased in SMA muscle cells. However, in mouse and human cultured SMA MNs mTOR phosphorylation and LC3-II levels were increased. These results suggest a differential regulation in SMA of the autophagy process in muscle cells and MNs. Opposite changes in autophagy proteins and mTOR phosphorylation between muscle cells and neurons were observed. These differences may reflect a specific response to SMN reduction, which could imply diverse tissue-dependent reactions to therapies that should be taken into account when treating SMA patients.

Keywords:  Autophagy; Human iPSCs; Motoneuron; Neurodegeneration; Neuromuscular disease; Spinal muscular atrophy; Survival motor neuron

DOI:  https://doi.org/10.1186/s40478-021-01223-5
J Clin Rheumatol. 2021 Feb 27.

Exercise Training Attenuates Ubiquitin-Proteasome Pathway and Increases the Genes Related to Autophagy on the Skeletal Muscle of Patients With Inflammatory Myopathies.

Isabela Bruna Pires Borges, Diego Sales de Oliveira, Suely Kazue Nagahashi Marie, Antonio Marcondes Lenario, Sueli Mieko Oba-Shinjo, Samuel Katsuyuki Shinjo.

BACKGROUND/OBJECTIVE: The aim of this study was to evaluate the effects of exercise training on the ubiquitin-proteasome system (UPS) and genes related to autophagy on the skeletal muscle of patients with dermatomyositis (DM) and immune-mediated necrotizing myopathies (IMNMs).METHODS: Seven DM patients and 6 IMNM patients were treated for 12 weeks with a twice-weekly aerobic and resistance training exercise program. Aerobic capacity, muscle strength, and expression of genes in the skeletal muscle related to UPS and to autophagy were evaluated at the baseline and after the intervention. Moreover, only at the baseline, 10 healthy control individuals were also evaluated.
RESULTS: The age of DM and IMNM patients was 49.8 and 58.5 years, respectively. Genes related to UPS were upregulated, whereas genes related to autophagy and antioxidative systems were downregulated only in the DM group when compared with control group. After completion of the exercise training program, several genes related to UPS were downregulated, whereas genes related to autophagy, mitochondrial pathways, and antioxidative systems were upregulated in both the DM and IMNM groups.
CONCLUSIONS: Exercise training can increase genes related to autophagy, mitophagy, and lysosomal biogenesis in the skeletal muscle of patients. These results suggest an increase in the recycling of damaged proteins and organelles, which may also contribute to the performance and endurance of skeletal muscles in these patients. Furthermore, in patients with myositis, exercise training led to a decrease in genes related to UPS and an increase in genes related to antioxidative capacity. Therefore, this may also contribute to an attenuation of skeletal muscle loss and of the deleterious effects of oxidative stress on the skeletal muscle of these patients.

DOI: https://doi.org/10.1097/RHU.0000000000001721
Int J Pharm. 2021 Jun 30. pii: S0378-5173(21)00646-3. [Epub ahead of print] 120841

3D Anisotropic Conductive Fibers Electrically Stimulated Myogenesis.

Yanping Zhang, Alice Le Friec, Menglin Chen.

Recapitulation of in vivo environments that drive muscle cells to organize into a physiologically relevant 3D architecture remains a major challenge for muscle tissue engineering. To recreate electrophysiology of muscle tissues, electroactive biomaterials have been used to stimulate muscle cells with exogenous electrical fields. In particular, the use of electroactive biomaterials with an anisotropic micro-/nanostructure that closely mimic the native skeletal-muscle extracellular matrix (ECM) is desirable for skeletal muscle tissue engineering. Herein, we present a hierarchically organized, anisotropic, and conductive PCL/Au scaffold for guiding myoblasts alignment and promoting the elongation and maturation of myotubes under electrical stimulation. Culturing with H9c2 myoblasts cells indicated that the nanotopographic cues was crucial for nuclei alignment, while the presence of microscale grooves effectively enhanced both the formation and elongation of myotubes. The anisotropic structure also leads to anisotropic conductivity. Under electrical stimulation, the elongation and maturation of myotubes were significantly enhanced along the anisotropic scaffold. Specifically, compared to the unstimulated group (0V), the myotube area percentage increased by 1.4, 1.9 and 2.4 times in the 1V, 2V, 3V groups, respectively. In addition, the myotube average length in the 1V group increased by 1.3 times compared to that of the unstimulated group, and significantly increased by 1.8 and 2.0 times in the 2V, 3V groups, respectively. Impressively, the longest myotubes reached more than 4 mm in both 2V and 3V groups. Overall, our conductive, anisotropic 3D nano/microfibrous scaffolds with the application of electrical stimulation provides a desirable platform for skeletal muscle tissue engineering.

DOI: https://doi.org/10.1016/j.ijpharm.2021.120841
Cell Rep. 2021 Jul 06. pii: S2211-1247(21)00712-9. [Epub ahead of print]36(1): 109336

Distribution of dietary protein intake in daily meals influences skeletal muscle hypertrophy via the muscle clock.

Shinya Aoyama, Hyeon-Ki Kim, Rina Hirooka, Mizuho Tanaka, Takeru Shimoda, Hanako Chijiki, Shuichi Kojima, Keisuke Sasaki, Kengo Takahashi, Saneyuki Makino, Miku Takizawa, Masaki Takahashi, Yu Tahara, Shigeki Shimba, Kazuyuki Shinohara, Shigenobu Shibata.

  The meal distribution of proteins throughout the day is usually skewed. However, its physiological implications and the effects of better protein distribution on muscle volume are largely unknown. Here, using the two-meals-per-day feeding model, we find that protein intake at the early active phase promotes overloading-induced muscle hypertrophy, in a manner dependent on the local muscle clock. Mice fed branched-chain amino acid (BCAA)-supplemented diets at the early active phase demonstrate skeletal muscle hypertrophy. However, distribution-dependent effects are not observed in ClockΔ19 or muscle-specific Bmal1 knockout mice. Additionally, we examined the relationship between the distribution of proteins in meals and muscle functions, such as skeletal muscle index and grip strength in humans. Higher muscle functions were observed in subjects who ingested dietary proteins mainly at breakfast than at dinner. These data suggest that protein intake at breakfast may be better for the maintenance of skeletal muscle mass.

Keywords:  BCAA; Bmal1; autophagy; breakfast; circadian rhythm; clock; dietary protein; hypertrophy; protein distribution; skeletal muscle

DOI:  https://doi.org/10.1016/j.celrep.2021.109336
Am J Chin Med. 2021 Jul 08. 1-19

14-Deoxy-11,12-Didehydroandrographolide Ameliorates Glucose Intolerance Enhancing the LKB1/AMPK[Formula: see text]/TBC1D1/GLUT4 Signaling Pathway and Inducing GLUT4 Expression in Myotubes and Skeletal Muscle of Obese Mice.

Chih-Chieh Chen, Chong-Kuei Lii, Chia-Wen Lo, Yi-Hsueh Lin, Ya-Chen Yang, Chin-Shiu Huang, Haw-Wen Chen.

  14-Deoxy-11,12-didehydroandrographolide (deAND), a bioactive component of Andrographis paniculata, has antidiabetic activity. AMP-activated protein kinase (AMPK) regulates glucose transport and ameliorates insulin resistance. The aim of the present study was to investigate whether activation of AMPK is involved in the mechanism by which deAND ameliorates insulin resistance in muscles. deAND amounts up to 40 [Formula: see text]M dose-dependently activated phosphorylation of AMPK[Formula: see text] and TBC1D1 in C2C12 myotubes. In addition, deAND significantly activated phosphorylation of LKB1 at 6 h after treatment, and this activation was maintained up to 48 h. deAND increased glucose uptake at 18 h after treatment, and this increase was time dependent up to 72 h. Compound C, an inhibitor of AMPK, suppressed deAND-induced phosphorylation of AMPK[Formula: see text] and TBC1D1 and reversed the effect on glucose uptake. In addition, the expression of GLUT4 mRNA and protein in C2C12 myotubes was up-regulated by deAND in a time-dependent manner. Promotion of GLUT4 gene transcription was verified by a pGL3-GLUT4 (837 bp) reporter assay. deAND also increased the nuclear translocation of MEF-2A and PPAR[Formula: see text]. After 16 weeks of feeding, the high-fat diet (HFD) inhibited phosphorylation of AMPK[Formula: see text] and TBC1D1 in skeletal muscle of obese C57BL/6JNarl mice, and deactivation of AMPK[Formula: see text] and TBC1D1 by the HFD was abolished by deAND supplementation. Supplementation with deAND significantly promoted membrane translocation of GLUT4 compared with the HFD group. Supplementation also significantly increased GLUT4 mRNA and protein expression in skeletal muscle compared with the HFD group. The hypoglycemic effects of deAND are likely associated with activation of the LKB1/AMPK[Formula: see text]/TBC1D1/GLUT4 signaling pathway and stimulation of MEF-2A- and PPAR[Formula: see text]-dependent GLUT4 gene expression, which account for the glucose uptake into skeletal muscle and lower blood glucose levels.

Keywords:  14-Deoxy-11,12-didehydroandrographolide (deAND); Andrographis Paniculata (AP); C2C12 Myotubes; Glucose Transporter 4 (GLUT4); Glucose Uptake

DOI:  https://doi.org/10.1142/S0192415X21500695
iScience. 2021 Jul 23. 24(7): 102712

Skeletal muscle proteomes reveal downregulation of mitochondrial proteins in transition from prediabetes into type 2 diabetes.

Tiina Öhman, Jaakko Teppo, Neeta Datta, Selina Mäkinen, Markku Varjosalo, Heikki A Koistinen.

  Skeletal muscle insulin resistance is a central defect in the pathogenesis of type 2 diabetes (T2D). Here, we analyzed skeletal muscle proteome in 148 vastus lateralis muscle biopsies obtained from men covering all glucose tolerance phenotypes: normal, impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and T2D. Skeletal muscle proteome was analyzed by a sequential window acquisition of all theoretical mass spectra (SWATH-MS) proteomics technique. Our data indicate a downregulation in several proteins involved in mitochondrial electron transport or respiratory chain complex assembly already in IFG and IGT muscles, with most profound decreases observed in T2D. Additional phosphoproteomic analysis reveals altered phosphorylation in several signaling pathways in IFG, IGT, and T2D muscles, including those regulating glucose metabolic processes, and the structure of muscle cells. These data reveal several alterations present in skeletal muscle already in prediabetes and highlight impaired mitochondrial energy metabolism in the trajectory from prediabetes into T2D.

Keywords:  Diabetology; Molecular biology; Proteomics

DOI:  https://doi.org/10.1016/j.isci.2021.102712
Diabetol Metab Syndr. 2021 Jul 06. 13(1): 74

Oxidative phenotype induced by aerobic physical training prevents the obesity-linked insulin resistance without changes in gastrocnemius muscle ACE2-Angiotensin(1-7)-Mas axis.

Bruno Vecchiatto, Rafael C da Silva, Talita S Higa, Cynthia R Muller, Anna Laura V Américo, Vanessa C Fortunato-Lima, Marília M Ferreira, Luiz Felipe Martucci, Miriam H Fonseca-Alaniz, Fabiana S Evangelista.

  BACKGROUND: We investigate the effect of aerobic physical training (APT) on muscle morphofunctional markers and Angiotensin Converting Enzyme 2/Angiotensin 1-7/Mas receptor (ACE2/Ang 1-7/Mas) axis in an obesity-linked insulin resistance (IR) animal model induced by cafeteria diet (CAF).METHODS: Male C57BL/6J mice were assigned into groups CHOW-SED (chow diet, sedentary; n = 10), CHOW-TR (chow diet, trained; n = 10), CAF-SED (n = 10) and CAF-TR (n = 10). APT consisted in running sessions of 60 min at 60% of maximal speed, 5 days per week for 8 weeks.
RESULTS: Trained groups had lower body weight and adiposity compared with sedentary groups. CAF-TR improved the glucose and insulin tolerance tests compared with CAF-SED group (AUC = 28.896 ± 1589 vs. 35.200 ± 1076 mg dL-1 120 min-1; kITT = 4.1 ± 0.27 vs. 2.5 ± 0.28% min-1, respectively). CHOW-TR and CAF-TR groups increased exercise tolerance, running intensity at which VO2 max was reached, the expression of p-AMPK, p-ACC and PGC1-α proteins compared with CHOW-SED and CAF-SED. Mithocondrial protein expression of Mfn1, Mfn2 and Drp1 did not change. Lipid deposition reduced in CAF-TR compared with CAF-SED group (3.71 vs. 5.53%/area), but fiber typing, glycogen content, ACE2 activity, Ang 1-7 concentration and Mas receptor expression did not change.
CONCLUSIONS: The APT prevents obesity-linked IR by modifying the skeletal muscle phenotype to one more oxidative independent of changes in the muscle ACE2/Ang 1-7/Mas axis.

Keywords:  AMPK pathway; Angiotensin 1-7; Exercise; Insulin resistance; Muscle metabolism

DOI:  https://doi.org/10.1186/s13098-021-00693-w
Endocrinol Metab (Seoul). 2021 Jun;36(3): 478-490

Receptor-Mediated Muscle Homeostasis as a Target for Sarcopenia Therapeutics.

Jong Hyeon Yoon, Ki-Sun Kwon.

  Sarcopenia is a disease characterized by age-related decline of skeletal muscle mass and function. The molecular mechanisms of the pathophysiology of sarcopenia form a complex network due to the involvement of multiple interconnected signaling pathways. Therefore, signaling receptors are major targets in pharmacological strategies in general. To provide a rationale for pharmacological interventions for sarcopenia, we herein describe several druggable signaling receptors based on their role in skeletal muscle homeostasis and changes in their activity with aging. A brief overview is presented of the efficacy of corresponding drug candidates under clinical trials. Strategies targeting the androgen receptor, vitamin D receptor, Insulin-like growth factor-1 receptor, and ghrelin receptor primarily focus on promoting anabolic action using natural ligands or mimetics. Strategies involving activin receptors and angiotensin receptors focus on inhibiting catabolic action. This review may help to select specific targets or combinations of targets in the future.

Keywords:  Aging; Clinical trial; Drug therapy; Molecular mechanisms of pharmacological action; Muscle, skeletal; Receptors, cell surface; Receptors, cytoplasmic and nuclear; Sarcopenia; Signal transduction

DOI:  https://doi.org/10.3803/EnM.2021.1081
Exp Gerontol. 2021 Jul 02. pii: S0531-5565(21)00247-3. [Epub ahead of print] 111465

Neuroprotective effects of exercise on the aging human neuromuscular system.

Matti D Allen, Brian H Dalton, Kevin J Gilmore, Chris J McNeil, Timothy J Doherty, Charles L Rice, Geoffrey A Power.

  Human biological aging from maturity to senescence is associated with a gradual loss of muscle mass and neuromuscular function. It is not until very old age (>80 years) however, that these changes often manifest into functional impairments. A driving factor underlying the age-related loss of muscle mass and function is the reduction in the number and quality of motor units (MUs). A MU consists of a single motoneuron, located either in the spinal cord or the brain stem, and all of the muscle fibres it innervates via its peripheral axon. Throughout the adult lifespan, MUs are slowly, but progressively lost. The compensatory process of collateral reinnervation attempts to recapture orphaned muscle fibres following the death of a motoneuron. Whereas this process helps mitigate loss of muscle mass during the latter decades of adult aging, the neuromuscular system has fewer and larger MUs, which have lower quality connections between the axon terminal and innervated muscle fibres. Whether this process of MU death and degradation can be attenuated with habitual physical activity has been a challenging question of great interest. This review focuses on age-related alterations of the human neuromuscular system, with an emphasis on the MU, and presents findings on the potential protective effects of lifelong physical activity. Although there is some discrepancy across studies of masters athletes, if one considers all experimental limitations as well as the available literature in animals, there is compelling evidence of a protective effect of chronic physical training on human MUs. Our tenet is that high-levels of physical activity can mitigate the natural trajectory of loss of quantity and quality of MUs in old age.

Keywords:  Atrophy; Masters athletes; Motor unit; Muscle; Neuroprotection; Physical activity; Sarcopenia; Training

DOI:  https://doi.org/10.1016/j.exger.2021.111465
STAR Protoc. 2021 Sep 17. 2(3): 100628

Analysis of proteostasis during aging with western blot of detergent-soluble and insoluble protein fractions.

Mamta Rai, Michelle Curley, Zane Coleman, Anjana Nityanandam, Jianqin Jiao, Flavia A Graca, Liam C Hunt, Fabio Demontis.

  Defects in protein quality control are the underlying cause of age-related diseases. The western blot analysis of detergent-soluble and insoluble protein fractions has proven useful in identifying interventions that regulate proteostasis. Here, we describe the protocol for such analyses in Drosophila tissues, mouse skeletal muscle, human organoids, and HEK293 cells. We describe key adaptations of this protocol and provide key information that will help modify this protocol for future studies in other tissues and disease models. For complete details on the use and execution of this protocol, please refer to Rai et al. (2021) and Hunt el al. (2021).

Keywords:  Cell Biology; Developmental biology; Model Organisms; Molecular Biology; Organoids; Protein Biochemistry

DOI:  https://doi.org/10.1016/j.xpro.2021.100628
Curr Opin Physiol. 2021 Jun;21 23-28

Proprioception revisited: where do we stand?

Jennifer L Shadrach, Julieta Gomez-Frittelli, Julia A Kaltschmidt.

Originally referred to as 'muscle sense', the notion that skeletal muscle held a peripheral sensory function was first described early in the 19th century. Foundational experiments by Sherrington in the early 20th century definitively demonstrated that proprioceptors contained within skeletal muscle, tendons, and joints are innervated by sensory neurons and play an important role in the control of movement. In this review, we will highlight several recent advances in the ongoing effort to further define the molecular diversity underlying the proprioceptive sensorimotor system. Together, the work summarized here represents our current understanding of sensorimotor circuit formation during development and the mechanisms that regulate the integration of proprioceptive feedback into the spinal circuits that control locomotion in both normal and diseased states.

DOI: https://doi.org/10.1016/j.cophys.2021.02.003
Biochimie. 2021 Jul 01. pii: S0300-9084(21)00170-X. [Epub ahead of print]

Muscles proteome analysis; irisin administration mimics some molecular effects of exercise in quadriceps muscle.

Sedigheh Momenzadeh, Saeed Zamani, Zahra Pourteymourfard-Tabrizi, Carlos Barreiro, Mohammad-Saeid Jami.

  Because of health-promoting effects, the adaptation of skeletal muscles to exercise is considered a therapeutic strategy for metabolic complications and musculoskeletal disabilities. Myokines display many beneficial effects of different exercise modalities. Among them, irisin is known as a systemic effector that positively influences several organs. There are a few studies about the effects of irisin on skeletal muscles, and irisin prosperities need to be well-defined for being an exercise mimetic. To aim this purpose, we assessed the proteome profile of mouse skeletal muscle after eight weeks of irisin injection comparing to resistance and endurance exercise treated groups. In the current study, two-dimensional gel electrophoresis was used to evaluate the protein content of the quadriceps muscle. The results were analyzed with Image Master 2D Platinum V6 software. Differentially expressed proteins were characterized by mass spectrometry (MALDI TOF/TOF) and interpreted using protein data banks and co-expression network. Irisin increases cellular ATP content by driving its overproduction through glycolysis and oxidative phosphorylation similar to two exercise protocols and as a specific property, decreases ATP consumption through creatine kinase downregulation. It also improves the microstructural properties of quadriceps muscle by increasing fiber proteins and might induce cellular proliferation and differentiation. Network analysis of differentially expressed proteins also revealed the co-expression of Irisin precursor with structural and metabolic-related proteins. The protein alterations after irisin administration display the potential of this myokine to mimic some molecular effects of exercise, suggesting it a promising candidate to improve muscle metabolism and structure.

Keywords:  Endurance exercise; Exercise adaptation; Hypertrophy; Irisin; Resistance exercise

DOI:  https://doi.org/10.1016/j.biochi.2021.06.016
J Cachexia Sarcopenia Muscle. 2021 Jul 04.

Matrisome, innervation and oxidative metabolism affected in older compared with younger males with similar physical activity.

Bart Lagerwaard, Arie G Nieuwenhuizen, Annelies Bunschoten, Vincent C J de Boer, Jaap Keijer.

  BACKGROUND: Due to the interaction between skeletal muscle ageing and lifestyle factors, it is often challenging to attribute the decline in muscle mass and quality to either changes in lifestyle or to advancing age itself. Because many of the physiological factors affecting muscle mass and quality are modulated by physical activity and physical activity declines with age, the aim of this study is to better understand the effects of early ageing on muscle function by comparing a population of healthy older and young males with similar physical activity patterns.METHODS: Eighteen older (69 ± 2.0 years) and 20 young (22 ± 2.0 years) males were recruited based on similar self-reported physical activity, which was verified using accelerometry measurements. Gene expression profiles of vastus lateralis biopsies obtained by RNA sequencing were compared, and key results were validated using quantitative polymerase chain reaction and western blot.
RESULTS: Total physical activity energy expenditure was similar between the young and old group (404 ± 215 vs. 411 ± 189 kcal/day, P = 0.11). Three thousand seven hundred ninety-seven differentially expressed coding genes (DEGs) were identified (adjusted P-value cut-off of <0.05), of which 1891 were higher and 1906 were lower expressed in the older muscle. The matrisome, innervation and inflammation were the main upregulated processes, and oxidative metabolism was the main downregulated process in old compared with young muscle. Lower protein levels of mitochondrial transcription factor A (TFAM, P = 0.030) and mitochondrial respiratory Complexes IV and II (P = 0.011 and P = 0.0009, respectively) were observed, whereas a trend was observed for Complex I (P = 0.062), in older compared with young muscle. Protein expression of Complexes I and IV was significantly correlated to mitochondrial capacity in the vastus lateralis as measured in vivo (P = 0.017, R2 = 0.42 and P = 0.030, R2 = 0.36). A trend for higher muscle-specific receptor kinase (MUSK) protein levels in the older group was observed (P = 0.08).
CONCLUSIONS: There are clear differences in the transcriptome signatures of the vastus lateralis muscle of healthy older and young males with similar physical activity levels, including significant differences at the protein level. By disentangling physical activity and ageing, we appoint early skeletal muscle ageing processes that occur despite similar physical activity. Improved understanding of these processes will be key to design targeted anti-ageing therapies.

Keywords:  Matrisome; Mitochondrial capacity; Muscle ageing; Physical activity

DOI:  https://doi.org/10.1002/jcsm.12753
Front Neurol. 2021 ;12 636719

Use of EP3533-Enhanced Magnetic Resonance Imaging as a Measure of Disease Progression in Skeletal Muscle of mdx Mice.

Alexander Peter Murphy, Elizabeth Greally, Dara O'Hogain, Andrew Blamire, Peter Caravan, Volker Straub.

  As putative treatments are developed for Duchenne muscular dystrophy (DMD), sensitive, non-invasive measures are increasingly important to quantify disease progression. Fibrosis is one of the histological hallmarks of muscular dystrophy and has been directly linked to prognosis. EP3533 is a novel contrast agent with an affinity to collagen 1 that has demonstrated a significant and high correlation to ex vivo fibrosis quantification. Halofuginone is an established anti-fibrotic compound shown to reduce collagen skeletal muscle fibrosis in murine models of DMD. This experiment explored whether EP3533 could be used to detect signal change in skeletal muscle of mdx mice before and after a 12 week course of halofuginone compared to controls. Four age-matched groups of treated and untreated mice were evaluated: 2 groups of mdx (n = 8 and n = 13, respectively), and 2 groups of BL10 mice (n = 5 and n = 3, respectively). Treated mice received an intraperitoneal injection with halofuginone three times per week for 12 weeks, with the remaining mice being given vehicle. Both mdx groups and the untreated BL10 were scanned at baseline, then all groups were scanned on week 13. All subjects were scanned using a 7T Varian scanner before and after administration of EP3533 using a T1 mapping technique. Mice underwent grip testing in week 13 prior to dissection. Skeletal muscle was used for Masson's trichrome quantification, hydroxyproline assay, and immunofluorescent antibody staining. Untreated mdx mice demonstrated a significant increase in R1 signal from pre- to post-treatment scan in three out of four muscles (gastrocnemius p = 0.04, hamstrings p = 0.009, and tibialis anterior p = 0.01), which was not seen in either the treated mdx or the BL10 groups. Histological quantification of fibrosis also demonstrated significantly higher levels in the untreated mdx mice with significant correlation seen between histology and EP3533 signal change. Forelimb weight adjusted-grip strength was significantly lower in the untreated mdx group, compared to the treated group. EP3533 can be used over time as an outcome measure to quantify treatment effect of an established anti-fibrotic drug. Further studies are needed to evaluate the use of this contrast agent in humans.

Keywords:  EP3533; fibrosis; magnetic resonance image; mdx mouse model; muscular dystrophy

DOI:  https://doi.org/10.3389/fneur.2021.636719
Cell Death Dis. 2021 Jul 03. 12(7): 671

Nrf2 activation induces mitophagy and reverses Parkin/Pink1 knock down-mediated neuronal and muscle degeneration phenotypes.

Sentiljana Gumeni, Eleni-Dimitra Papanagnou, Maria S Manola, Ioannis P Trougakos.

The balanced functionality of cellular proteostatic modules is central to both proteome stability and mitochondrial physiology; thus, the age-related decline of proteostasis also triggers mitochondrial dysfunction, which marks multiple degenerative disorders. Non-functional mitochondria are removed by mitophagy, including Parkin/Pink1-mediated mitophagy. A common feature of neuronal or muscle degenerative diseases, is the accumulation of damaged mitochondria due to disrupted mitophagy rates. Here, we exploit Drosophila as a model organism to investigate the functional role of Parkin/Pink1 in regulating mitophagy and proteostatic responses, as well as in suppressing degenerative phenotypes at the whole organism level. We found that Parkin or Pink1 knock down in young flies modulated proteostatic components in a tissue-dependent manner, increased cell oxidative load, and suppressed mitophagy in neuronal and muscle tissues, causing mitochondrial aggregation and neuromuscular degeneration. Concomitant to Parkin or Pink1 knock down cncC/Nrf2 overexpression, induced the proteostasis network, suppressed oxidative stress, restored mitochondrial function, and elevated mitophagy rates in flies' tissues; it also, largely rescued Parkin or Pink1 knock down-mediated neuromuscular degenerative phenotypes. Our in vivo findings highlight the critical role of the Parkin/Pink1 pathway in mitophagy, and support the therapeutic potency of Nrf2 (a druggable pathway) activation in age-related degenerative diseases.

DOI: https://doi.org/10.1038/s41419-021-03952-w
Front Genet. 2021 ;12 650874

Investigating Transcriptional Dynamics Changes and Time-Dependent Marker Gene Expression in the Early Period After Skeletal Muscle Injury in Rats.

Kang Ren, Liangliang Wang, Liang Wang, Qiuxiang Du, Jie Cao, Qianqian Jin, Guoshuai An, Na Li, Lihong Dang, Yingjie Tian, Yingyuan Wang, Junhong Sun.

  Following skeletal muscle injury (SMI), from post-injury reaction to repair consists of a complex series of dynamic changes. However, there is a paucity of research on detailed transcriptional dynamics and time-dependent marker gene expression in the early stages after SMI. In this study, skeletal muscle tissue in rats was taken at 4 to 48 h after injury for next-generation sequencing. We examined the transcriptional kinetics characteristics during above time periods after injury. STEM and maSigPro were used to screen time-correlated genes. Integrating 188 time-correlated genes with 161 genes in each time-related gene module by WGCNA, we finally identified 18 network-node regulatory genes after SMI. Histological staining analyses confirmed the mechanisms underlying changes in the tissue damage to repair process. Our research linked a variety of dynamic biological processes with specific time periods and provided insight into the characteristics of transcriptional dynamics, as well as screened time-related biological indicators with biological significance in the early stages after SMI.

Keywords:  gene expression and regulation landscape; skeletal muscle injury; time-related biomarkers; time-series RNA-seq; transcriptional dynamics

DOI:  https://doi.org/10.3389/fgene.2021.650874
JCI Insight. 2021 Jul 08. pii: 149446. [Epub ahead of print]6(13):

Combining multiomics and drug perturbation profiles to identify muscle-specific treatments for spinal muscular atrophy.

Katharina E Meijboom, Viola Volpato, Jimena Monzón-Sandoval, Joseph M Hoolachan, Suzan M Hammond, Frank Abendroth, Olivier G de Jong, Gareth Hazell, Nina Ahlskog, Matthew Ja Wood, Caleb Webber, Melissa Bowerman.

  Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by loss of survival motor neuron (SMN) protein. While SMN restoration therapies are beneficial, they are not a cure. We aimed to identify potentially novel treatments to alleviate muscle pathology combining transcriptomics, proteomics, and perturbational data sets. This revealed potential drug candidates for repurposing in SMA. One of the candidates, harmine, was further investigated in cell and animal models, improving multiple disease phenotypes, including lifespan, weight, and key molecular networks in skeletal muscle. Our work highlights the potential of multiple and parallel data-driven approaches for the development of potentially novel treatments for use in combination with SMN restoration therapies.

Keywords:  Bioinformatics; Drug therapy; Genetic diseases; Muscle Biology; Neuroscience

DOI:  https://doi.org/10.1172/jci.insight.149446
Free Radic Res. 2021 Jul 08. 1-48

Redox interactions of immune cells and muscle in the regulation of exercise-induced pain and analgesia: implications on the modulation of muscle nociceptor sensory neurons.

Sylvia K D Bussulo, Camila R Ferraz, Thacyana T Carvalho, Waldiceu A Verri, Sergio M Borghi.

  The mechanistic interactions among redox status of leukocytes, muscle, and exercise in pain regulation are still poorly understood and limits targeted treatment. Exercise benefits are numerous, including the treatment of chronic pain. However, unaccustomed exercise may be reported as undesirable as it may contribute to pain. The aim of the present review is to evaluate the relationship between oxidative metabolism and acute exercise-induced pain, and as to whether improved antioxidant capacity underpins the analgesic effects of regular exercise. Preclinical and clinical studies addressing relevant topics on mechanisms by which exercise modulates nociceptive activity and how redox status can outline pain and analgesia are discussed, in sense of translating into refined outcomes. Emerging evidence points to the role of oxidative stress-induced signaling in sensitizing nociceptor sensory neurons. In response to acute exercise, there is an increase in oxidative metabolism, and consequently, pain. Instead, regular exercise can modulate redox status in favor of antioxidant capacity and repair mechanisms, which have consequently increased resistance to oxidative stress, damage, and pain. Data indicate that acute sessions of unaccustomed prolonged and/or intense exercise increase oxidative metabolism and regulates exercise-induced pain in the post-exercise recovery period. Further, evidence demonstrates regular exercise improves antioxidant status, indicating its therapeutic utility for chronic pain disorders. An improved comprehension of the role of redox status in exercise can provide helpful insights into immune-muscle communication during pain modulatory effects of exercise and support new therapeutic efforts and rationale for the promotion of exercise.

Keywords:  Redox status; analgesia; exercise; immune cells; muscle; pain

DOI:  https://doi.org/10.1080/10715762.2021.1953696