bims-moremu 2023-09-17 papers

bims-moremu

Biomed News

on Molecular regulators of muscle mass

Issue of 2023‒09‒17
twenty-six papers selected by
Anna Vainshtein, Craft Science Inc.

Complex regulatory processes control exercise adaptations of skeletal muscle.
Discordant skeletal muscle gene and protein responses to exercise.
Methylome and proteome integration in human skeletal muscle uncover group and individual responses to high-intensity interval training.
Seasonal light hours modulate peripheral clocks and energy metabolism in mice.
Molecular control of endurance training adaptation in male mouse skeletal muscle.
Partial Skeletal Muscle-Specific Drp1 Knockout Enhances Insulin Sensitivity in Diet-Induced Obese Mice, But Not in Lean Mice.
Impacts of radiation exposure, hindlimb unloading, and recovery on murine skeletal muscle cell telomere length.
Detyrosinated microtubule arrays drive myofibrillar malformations in mdx muscle fibers.
Meta-analysis data of skeletal muscle slow fiber content across mammalian species.
Sox11 is enriched in myogenic progenitors but dispensable for development and regeneration of the skeletal muscle.
Resistance exercise alleviates dexamethasone-induced muscle atrophy via Sestrin2/MSTN pathway in C57BL/6J mice.
iMS-Bmal1-/- mice show evident signs of sarcopenia that are counteracted by exercise and melatonin therapies.
Sepsis leads to impaired mitochondrial calcium uptake and skeletal muscle weakness by reducing the MICU1:MCU protein ratio.
Human skeletal muscle tissue chip autonomous payload reveals changes in fiber type and metabolic gene expression due to spaceflight.
miRNA-126a plays important role in myoblast and endothelial cell interaction.
Short-term repeated human biopsy sampling contributes to changes in muscle morphology and higher outcome variability.
Relative quantification of progressive changes in healthy and dysferlin-deficient mouse skeletal muscle proteomes.
Injury-experienced satellite cells retain long-term enhanced regenerative capacity.
Redox state and altered pyruvate metabolism contribute to a dose-dependent metformin-induced lactate production of human myotubes.
Speg interactions that regulate the stability of excitation-contraction coupling protein complexes in triads and dyads.
Deficiency of endothelial sirtuin1 in mice stimulates skeletal muscle insulin sensitivity by modifying the secretome.
Bulk and single-cell alternative splicing analyses reveal roles of TRA2B in myogenic differentiation.
MATR3 is an endogenous inhibitor of DUX4 in FSHD muscular dystrophy.
The combination of quercetin and leucine synergistically improves grip strength by attenuating muscle atrophy by multiple mechanisms in mice exposed to cisplatin.
Skeletal muscle mitochondria in strength athletes: meeting energy needs with mitochondrial morphological changes.
Skeletal Muscle-derived FSTL1 Starting up Angiogenesis by Regulating Endothelial Junction via Activating Src Pathway Can be Upregulated by Hydrogen Sulfide.

Nat Metab. 2023 Sep 14.

Complex regulatory processes control exercise adaptations of skeletal muscle.

DOI: https://doi.org/10.1038/s42255-023-00894-9
Trends Biochem Sci. 2023 Sep 12. pii: S0968-0004(23)00208-6. [Epub ahead of print]

Discordant skeletal muscle gene and protein responses to exercise.

David J Bishop, Nolan J Hoffman, Dale F Taylor, Nicholas J Saner, Matthew J-C Lee, John A Hawley.

  The ability of skeletal muscle to adapt to repeated contractile stimuli is one of the most intriguing aspects of physiology. The molecular bases underpinning these adaptations involve increased protein activity and/or expression, mediated by an array of pre- and post-transcriptional processes, as well as translational and post-translational control. A longstanding dogma assumes a direct relationship between exercise-induced increases in mRNA levels and subsequent changes in the abundance of the proteins they encode. Drawing on the results of recent studies, we dissect and question the common assumption of a direct relationship between changes in the skeletal muscle transcriptome and proteome induced by repeated muscle contractions (e.g., exercise).

Keywords:  exercise training; mRNA; physical activity; skeletal muscle; transcription

DOI:  https://doi.org/10.1016/j.tibs.2023.08.005
FASEB J. 2023 10;37(10): e23184

Methylome and proteome integration in human skeletal muscle uncover group and individual responses to high-intensity interval training.

Macsue Jacques, Shanie Landen, Javier Alvarez Romero, Danielle Hiam, Ralf B Schittenhelm, Iresha Hanchapola, Anup D Shah, Sarah Voisin, Nir Eynon.

  Exercise is a major beneficial contributor to muscle metabolism, and health benefits acquired by exercise are a result of molecular shifts occurring across multiple molecular layers (i.e., epigenome, transcriptome, and proteome). Identifying robust, across-molecular level targets associated with exercise response, at both group and individual levels, is paramount to develop health guidelines and targeted health interventions. Sixteen, apparently healthy, moderately trained (VO2 max = 51.0 ± 10.6 mL min-1 kg-1 ) males (age range = 18-45 years) from the Gene SMART (Skeletal Muscle Adaptive Responses to Training) study completed a longitudinal study composed of 12-week high-intensity interval training (HIIT) intervention. Vastus lateralis muscle biopsies were collected at baseline and after 4, 8, and 12 weeks of HIIT. DNA methylation (~850 CpG sites) and proteomic (~3000 proteins) analyses were conducted at all time points. Mixed models were applied to estimate group and individual changes, and methylome and proteome integration was conducted using a holistic multilevel approach with the mixOmics package. A total of 461 proteins significantly changed over time (at 4, 8, and 12 weeks), whilst methylome overall shifted with training only one differentially methylated position (DMP) was significant (adj.p-value < .05). K-means analysis revealed cumulative protein changes by clusters of proteins that presented similar changes over time. Individual responses to training were observed in 101 proteins. Seven proteins had large effect-sizes >0.5, among them are two novel exercise-related proteins, LYRM7 and EPN1. Integration analysis showed bidirectional relationships between the methylome and proteome. We showed a significant influence of HIIT on the epigenome and more so on the proteome in human muscle, and uncovered groups of proteins clustering according to similar patterns across the exercise intervention. Individual responses to exercise were observed in the proteome with novel mitochondrial and metabolic proteins consistently changed across individuals. Future work is required to elucidate the role of these proteins in response to exercise.

Keywords:  DNA methylation; epigenetics; exercise; proteomics; skeletal muscle

DOI:  https://doi.org/10.1096/fj.202300840RR
Cell Metab. 2023 Sep 01. pii: S1550-4131(23)00300-5. [Epub ahead of print]

Seasonal light hours modulate peripheral clocks and energy metabolism in mice.

Lewin Small, Leonidas S Lundell, Jo Iversen, Amy M Ehrlich, Morten Dall, Astrid L Basse, Emilie Dalbram, Ann N Hansen, Jonas T Treebak, Romain Barrès, Juleen R Zierath.

  Except for latitudes close to the equator, seasonal variation in light hours can change dramatically between summer and winter. Yet investigations into the interplay between energy metabolism and circadian rhythms typically use a 12 h light:12 h dark photoperiod corresponding to the light duration at the equator. We hypothesized that altering the seasonal photoperiod affects both the rhythmicity of peripheral tissue clocks and energy homeostasis. Mice were housed at photoperiods representing either light hours in summer, winter, or the equinox. Mice housed at a winter photoperiod exhibited an increase in the amplitude of rhythmic lipid metabolism and a modest reduction in fat mass and liver triglyceride content. Comparing melatonin-proficient and -deficient mice, the effect of seasonal light on energy metabolism was largely driven by differences in the rhythmicity of food intake and not melatonin. Together, these data indicate that seasonal light impacts energy metabolism by modulating the timing of eating.

Keywords:  circadian biology; energy homeostasis; glucose metabolism; hormones; integrative physiology; obesity; transcriptomics

DOI:  https://doi.org/10.1016/j.cmet.2023.08.005
Nat Metab. 2023 Sep 11.

Molecular control of endurance training adaptation in male mouse skeletal muscle.

Regula Furrer, Barbara Heim, Svenia Schmid, Sedat Dilbaz, Volkan Adak, Karl J V Nordström, Danilo Ritz, Stefan A Steurer, Jörn Walter, Christoph Handschin.

Skeletal muscle has an enormous plastic potential to adapt to various external and internal perturbations. Although morphological changes in endurance-trained muscles are well described, the molecular underpinnings of training adaptation are poorly understood. We therefore aimed to elucidate the molecular signature of muscles of trained male mice and unravel the training status-dependent responses to an acute bout of exercise. Our results reveal that, even though at baseline an unexpectedly low number of genes define the trained muscle, training status substantially affects the transcriptional response to an acute challenge, both quantitatively and qualitatively, in part associated with epigenetic modifications. Finally, transiently activated factors such as the peroxisome proliferator-activated receptor-γ coactivator 1α are indispensable for normal training adaptation. Together, these results provide a molecular framework of the temporal and training status-dependent exercise response that underpins muscle plasticity in training.

DOI: https://doi.org/10.1038/s42255-023-00891-y
Mol Metab. 2023 Sep 08. pii: S2212-8778(23)00136-9. [Epub ahead of print] 101802

Partial Skeletal Muscle-Specific Drp1 Knockout Enhances Insulin Sensitivity in Diet-Induced Obese Mice, But Not in Lean Mice.

Benjamin A Kugler, Jared Lourie, Nicolas Berger, Nana Lin, Paul Nguyen, Edzana DosSantos, Abir Ali, Amira Sesay, H Grace Rosen, Baby Kalemba, Gregory M Hendricks, Joseph A Houmard, Hiromi Sesaki, Philimon Gona, Tongjian You, Zhen Yan, Kai Zou.

  OBJECTIVE: Dynamin-related protein 1 (Drp1) is the key regulator of mitochondrial fission. We and others have reported a strong correlation between enhanced Drp1 activity and impaired skeletal muscle insulin sensitivity. This study aimed to determine whether Drp1 directly regulates skeletal muscle insulin sensitivity and whole-body glucose homeostasis.METHODS: We employed tamoxifen-inducible skeletal muscle-specific heterozygous Drp1 knockout mice (mDrp1+/-). Male mDrp1+/- and wildtype (WT) mice were fed with either a high-fat diet (HFD) or low-fat diet (LFD) for four weeks, followed by tamoxifen injections for five consecutive days, and remained on their respective diet for another four weeks. In addition, we used primary human skeletal muscle cells (HSkMC) from lean, insulin-sensitive, and severely obese, insulin-resistant humans and transfected the cells with either a Drp1 shRNA (shDrp1) or scramble shRNA construct. Skeletal muscle and whole-body insulin sensitivity, skeletal muscle insulin signaling, mitochondrial network morphology, respiration, and H2O2 production were measured.
RESULTS: Partial deletion of the Drp1 gene in skeletal muscle led to improved whole-body glucose tolerance and insulin sensitivity (P<0.05) in diet-induced obese, insulin-resistant mice but not in lean mice. Analyses of mitochondrial structure and function revealed that the partial deletion of the Drp1 gene restored mitochondrial dynamics, improved mitochondrial morphology, and reduced mitochondrial Complex I- and II-derived H2O2 (P<0.05) under the condition of diet-induced obesity. In addition, partial deletion of Drp1 in skeletal muscle resulted in elevated circulating FGF21 (P<0.05) and in a trend towards increase of FGF21 expression in skeletal muscle tissue (P=0.095). In primary myotubes derived from severely obese, insulin-resistant humans, ShRNA-induced-knockdown of Drp1 resulted in enhanced insulin signaling, insulin-stimulated glucose uptake and reduced cellular reactive oxygen species (ROS) content compared to the shScramble-treated myotubes from the same donors (P<0.05).
CONCLUSION: These data demonstrate that partial loss of skeletal muscle-specific Drp1 expression is sufficient to improve whole-body glucose homeostasis and insulin sensitivity under obese, insulin-resistant conditions, which may be, at least in part, due to reduced mitochondrial H2O2 production. In addition, our findings revealed divergent effects of Drp1 on whole-body metabolism under lean healthy or obese insulin-resistant conditions in mice.

Keywords:  Insulin sensitivity; Mitochondrial H (2)O(2); Mitochondrial dynamics; Mitochondrial fission

DOI:  https://doi.org/10.1016/j.molmet.2023.101802
NPJ Microgravity. 2023 Sep 15. 9(1): 76

Impacts of radiation exposure, hindlimb unloading, and recovery on murine skeletal muscle cell telomere length.

Elisia D Tichy, Ji-Hyung Lee, Grant Li, Katrina N Estep, F Brad Johnson, Foteini Mourkioti.

Astronauts are exposed to harsh conditions, including cosmic radiation and microgravity. Spaceflight elongates human telomeres in peripheral blood, which shorten upon return to Earth and approach baseline levels during postflight recovery. Astronauts also encounter muscle atrophy, losing up to 20% loss of muscle mass on spaceflights. Telomere length changes in muscle cells of astronauts remain unexplored. This study investigates telomere alterations in grounded mice experiencing radiation exposure and muscle atrophy, via a hindlimb unloading spaceflight mimicking model. We find telomere lengthening is present in muscle stem cells and in myofiber nuclei, but not in muscle-resident endothelial cells. We further assessed telomere length in the model following hindlimb unloading recovery. We find that telomere length failed to return to baseline values. Our results suggest a role for telomeres in muscle acclimatization, which is relevant for the well-being of astronauts in space, and upon their return to Earth.

DOI: https://doi.org/10.1038/s41526-023-00303-1
Front Cell Dev Biol. 2023 ;11 1209542

Detyrosinated microtubule arrays drive myofibrillar malformations in mdx muscle fibers.

Anicca D Harriot, Tessa Altair Morris, Camilo Vanegas, Jacob Kallenbach, Kaylie Pinto, Humberto C Joca, Marie-Jo Moutin, Guoli Shi, Jeanine A Ursitti, Anna Grosberg, Christopher W Ward.

  Altered myofibrillar structure is a consequence of dystrophic pathology that impairs skeletal muscle contractile function and increases susceptibility to contraction injury. In murine Duchenne muscular dystrophy (mdx), myofibrillar alterations are abundant in advanced pathology (>4 months), an age where we formerly established densified microtubule (MT) arrays enriched in detyrosinated (deTyr) tubulin as negative disease modifiers impacting cell mechanics and mechanotransduction. Given the essential role of deTyr-enriched MT arrays in myofibrillar growth, maintenance, and repair, we examined the increased abundance of these arrays as a potential mechanism for these myofibrillar alterations. Here we find an increase in deTyr-tubulin as an early event in dystrophic pathology (4 weeks) with no evidence myofibrillar alterations. At 16 weeks, we show deTyr-enriched MT arrays significantly densified and co-localized to areas of myofibrillar malformation. Profiling the enzyme complexes responsible for deTyr-tubulin, we identify vasohibin 2 (VASH2) and small vasohibin binding protein (SVBP) significantly elevated in the mdx muscle at 4 weeks. Using the genetic increase in VASH2/SVBP expression in 4 weeks wild-type mice we find densified deTyr-enriched MT arrays that co-segregate with myofibrillar malformations similar to those in the 16 weeks mdx. Given that no changes in sarcomere organization were identified in fibers expressing sfGFP as a control, we conclude that disease-dependent densification of deTyr-enriched MT arrays underscores the altered myofibrillar structure in dystrophic skeletal muscle fibers.

Keywords:  detyrosination; dystrophy; microtubule array; myoarchitecture; skeletal muscle

DOI:  https://doi.org/10.3389/fcell.2023.1209542
Data Brief. 2023 Oct;50 109520

Meta-analysis data of skeletal muscle slow fiber content across mammalian species.

Samantha R Queeno, Kirstin N Sterner, Matthew C O'Neill.

  Herein, the dataset generated for Queeno et al. [1] is presented and described. Mammalian skeletal muscle slow (MyHC-I) fiber composition data was collated from 269 eligible studies identified via a systematic literature search and meta-analysis, following a structure similar to PRISMA [2]. Academic search systems were queried with terms relating to mammalian skeletal muscle fiber content and reference lists of selected articles were thoroughly investigated for additional studies. Eligible studies were those that provided skeletal muscle fiber composition data from mammalian species that were not subjected to experimental manipulations. Taxonomic information, sex, age, number of individuals sampled, average body mass (kg), average slow fiber content (%) of each skeletal muscle under investigation and fiber-typing methodology were collated from eligible studies when available. Muscle fiber composition data was collected from more than 200 skeletal muscles across 174 mammalian species, which will be of value to those interested in muscle physiology, interspecific muscle comparisons, and connections between muscle physiology, taxonomy, body mass, ecomorphology and locomotor strategy (among others).

Keywords:  Fiber typing; Interspecific muscle physiology comparison; Muscle fiber composition; MyHC I; Myosin heavy chain I; Slow-twitch

DOI:  https://doi.org/10.1016/j.dib.2023.109520
Skelet Muscle. 2023 Sep 13. 13(1): 15

Sox11 is enriched in myogenic progenitors but dispensable for development and regeneration of the skeletal muscle.

Stephanie N Oprescu, Nick Baumann, Xiyue Chen, Qiang Sun, Yu Zhao, Feng Yue, Huating Wang, Shihuan Kuang.

  Transcription factors (TFs) play key roles in regulating differentiation and function of stem cells, including muscle satellite cells (MuSCs), a resident stem cell population responsible for postnatal regeneration of the skeletal muscle. Sox11 belongs to the Sry-related HMG-box (SOX) family of TFs that play diverse roles in stem cell behavior and tissue specification. Analysis of single-cell RNA-sequencing (scRNA-seq) datasets identify a specific enrichment of Sox11 mRNA in differentiating but not quiescent MuSCs. Consistent with the scRNA-seq data, Sox11 levels increase during differentiation of murine primary myoblasts in vitro. scRNA-seq data comparing muscle regeneration in young and old mice further demonstrate that Sox11 expression is reduced in aged MuSCs. Age-related decline of Sox11 expression is associated with reduced chromatin contacts within the topologically associating domains. Unexpectedly, Myod1Cre-driven deletion of Sox11 in embryonic myoblasts has no effects on muscle development and growth, resulting in apparently healthy muscles that regenerate normally. Pax7CreER- or Rosa26CreER- driven (MuSC-specific or global) deletion of Sox11 in adult mice similarly has no effects on MuSC differentiation or muscle regeneration. These results identify Sox11 as a novel myogenic differentiation marker with reduced expression in quiescent and aged MuSCs, but the specific function of Sox11 in myogenesis remains to be elucidated.

Keywords:  Aging; Differentiation; SRY-box transcription factor; Satellite cells; Single-cell RNA-sequencing (scRNA-seq); Stem cells

DOI:  https://doi.org/10.1186/s13395-023-00324-0
Exp Cell Res. 2023 Sep 12. pii: S0014-4827(23)00327-0. [Epub ahead of print] 113779

Resistance exercise alleviates dexamethasone-induced muscle atrophy via Sestrin2/MSTN pathway in C57BL/6J mice.

Yang Yang, Xuege Yang, Yating Huang, Sujuan Liu, Yanmei Niu, Li Fu.

  AIM: It has long been recognized that resistance exercise can substantially increase skeletal muscle mass and strength, but whether it can protect against glucocorticoid-induced muscle atrophy and its potential mechanism is yet to be determined. This study aimed to investigate the protective effects of resistance exercise in dexamethasone-induced muscle atrophy and elucidate the possible function of exercise-induced protein Sestrin2 in this process.METHODS: Eight-week-old male C57BL/6J mice carried out the incremental mouse ladder exercise for 11 weeks. Two weeks before the end of the intervention, mice were daily intraperitoneally injected with dexamethasone. Body composition, muscle mass, and exercise performance were examined to evaluate muscle atrophy. In vitro, C2C12 cells were used for RT-qPCR, Western Blot, and immunofluorescence experiments to elucidate the potential mechanism.
RESULTS: Our results showed that long-term resistance exercise is an effective intervention for dexamethasone-induced muscle atrophy. We also found that Sestrin2 plays a vital role in dexamethasone-induced muscle atrophy. In both animal (P = .0006) and cell models (P = .0266), dexamethasone intervention significantly reduced the protein expression of Sestrin2, which was increased (P = .0112) by resistance exercise. Inversely, overexpression of Sestrin2 improved (P < .0001) dexamethasone-induced myotube cell atrophy by reducing the activation of the ubiquitin-proteasome pathway via inhibiting Forkhead box O3 (FoxO3a) and myostatin (MSTN)/small mother against decapentaplegic (Smad) signaling pathways.
CONCLUSION: Taken together, our results indicated that Sestrin2 may serve as an effective molecule that mimics the protective effect of resistance exercise on dexamethasone-induced muscle atrophy.

Keywords:  FoxO3a; Myostatin; Protein degradation; Resistance exercise; Sestrin2; Skeletal muscle atrophy

DOI:  https://doi.org/10.1016/j.yexcr.2023.113779
J Pineal Res. 2023 Sep 13. e12912

iMS-Bmal1-/- mice show evident signs of sarcopenia that are counteracted by exercise and melatonin therapies.

José Fernández-Martínez, Yolanda Ramírez-Casas, Paula Aranda-Martínez, Alba López-Rodríguez, Ramy K A Sayed, Germaine Escames, Darío Acuña-Castroviejo.

  Sarcopenia is an age-related disease characterized by a reduction in muscle mass, strength, and function and, therefore, a deterioration in skeletal muscle health and frailty. Although the cause of sarcopenia is still unknown and, thus, there is no treatment, increasing evidence suggests that chronodisruption, particularly alterations in Bmal1 clock gene, can lead to those deficits culminating in sarcopenia. To gain insight into the cause and mechanism of sarcopenia and the protective effect of a therapeutic intervention with exercise and/or melatonin, the gastrocnemius muscles of male and female skeletal muscle-specific and inducible Bmal1 knockout mice (iMS-Bmal1-/- ) were examined by phenotypic tests and light and electron microscopy. Our results revealed a disruption of the normal activity/rest rhythm, a drop in skeletal muscle function and mass, and increased frailty in male and female iMS-Bmal1-/- animals compared to controls. A reduction in muscle fiber size and increased collagenous tissue were also detected, accompanied by reduced mitochondrial oxidative capacity and a compensatory shift towards a more oxidative fiber type. Electron microscopy further supports mitochondrial impairment in mutant mice. Melatonin and exercise ameliorated the damage caused by loss of Bmal1 in mutant mice, except for mitochondrial damage, which was worsened by the latter. Thus, iMS-Bmal1-/- mice let us to identify Bmal1 deficiency as the responsible for the appearance of sarcopenia in the gastrocnemius muscle. Moreover, the results support the exercise and melatonin as therapeutic tools to counteract sarcopenia, by a mechanism that does not require the presence of Bmal1.

Keywords:  Bmal1; chronodisruption; exercise; frailty; gastrocnemius muscle; melatonin; sarcopenia

DOI:  https://doi.org/10.1111/jpi.12912
Shock. 2023 Sep 05.

Sepsis leads to impaired mitochondrial calcium uptake and skeletal muscle weakness by reducing the MICU1:MCU protein ratio.

Xuexin Li, Bowen Sun, Jie Li, Wanlin Ye, Mingjuan Li, Fasheng Guan, Songlin Wu, Xuerong Luo, Jianguo Feng, Jing Jia, Xueru Liu, Tao Li, Li Liu.

PURPOSE: Intensive care unit-acquired weakness (ICUAW) is a severe neuromuscular complication that frequently occurs in patients with sepsis. The precise molecular pathophysiology of mitochondrial calcium uptake 1 (MICU1) and mitochondrial calcium uniporter (MCU) in ICUAW has not been fully elucidated. Here, we speculate that ICUAW is associated with MICU1:MCU protein ratio-mediated mitochondrial calcium ([Ca2+]m) uptake dysfunction.METHODS: Cecal ligation and perforation (CLP) was performed on C57BL/6 J mice to induce sepsis. Sham-operated animals were used as controls. Lipopolysaccharide (LPS) (5 μg/mL) was used to induce inflammation in differentiated C2C12 myoblasts. Compound muscle action potential (CMAP) was detected using a biological signal acquisition system. Grip strength was measured using a grip-strength meter. Skeletal muscle inflammatory factors were detected using ELISA kits. The cross-sectional area (CSA) of the tibialis anterior (TA) muscle was detected by hematoxylin and eosin staining. Cytosolic calcium ([Ca2+]c) levels were measured using Fluo-4 AM. Adeno-associated virus (AAV) was injected into TA muscles for 4 weeks to overexpress MICU1 prophylactically. A lentivirus was used to infect C2C12 cells to increase MICU1 expression prophylactically.
FINDINGS: The results suggest that sepsis induces [Ca2+]m uptake disorder by reducing the MICU1:MCU protein ratio, resulting in skeletal muscle weakness and muscle fiber atrophy. However, MICU1 prophylactic overexpression reversed these effects by increasing the MICU1:MCU protein ratio.
CONCLUSIONS: ICUAW is associated with impaired [Ca2+]m uptake caused by a decreased MICU1:MCU protein ratio. MICU1 overexpression improves sepsis-induced skeletal muscle weakness and atrophy by ameliorating the [Ca2+]m uptake disorder.

DOI: https://doi.org/10.1097/SHK.0000000000002221
NPJ Microgravity. 2023 Sep 15. 9(1): 77

Human skeletal muscle tissue chip autonomous payload reveals changes in fiber type and metabolic gene expression due to spaceflight.

Maddalena Parafati, Shelby Giza, Tushar S Shenoy, Jorge A Mojica-Santiago, Meghan Hopf, Legrand K Malany, Don Platt, Isabel Moore, Zachary A Jacobs, Paul Kuehl, Jason Rexroat, Gentry Barnett, Christine E Schmidt, William T McLamb, Twyman Clements, Paul M Coen, Siobhan Malany.

Microphysiological systems provide the opportunity to model accelerated changes at the human tissue level in the extreme space environment. Spaceflight-induced muscle atrophy experienced by astronauts shares similar physiological changes to muscle wasting in older adults, known as sarcopenia. These shared attributes provide a rationale for investigating molecular changes in muscle cells exposed to spaceflight that may mimic the underlying pathophysiology of sarcopenia. We report the results from three-dimensional myobundles derived from muscle biopsies from young and older adults, integrated into an autonomous CubeLab™, and flown to the International Space Station (ISS) aboard SpaceX CRS-21 as part of the NIH/NASA funded Tissue Chips in Space program. Global transcriptomic RNA-Seq analyses comparing the myobundles in space and on the ground revealed downregulation of shared transcripts related to myoblast proliferation and muscle differentiation. The analyses also revealed downregulated differentially expressed gene pathways related to muscle metabolism unique to myobundles derived from the older cohort exposed to the space environment compared to ground controls. Gene classes related to inflammatory pathways were downregulated in flight samples cultured from the younger cohort compared to ground controls. Our muscle tissue chip platform provides an approach to studying the cell autonomous effects of spaceflight on muscle cell biology that may not be appreciated on the whole organ or organism level and sets the stage for continued data collection from muscle tissue chip experimentation in microgravity. We also report on the challenges and opportunities for conducting autonomous tissue-on-chip CubeLabTM payloads on the ISS.

DOI: https://doi.org/10.1038/s41526-023-00322-y
Sci Rep. 2023 Sep 12. 13(1): 15046

miRNA-126a plays important role in myoblast and endothelial cell interaction.

Bartosz Mierzejewski, Maria Anna Ciemerych, Wladyslawa Streminska, Katarzyna Janczyk-Ilach, Edyta Brzoska.

Muscle satellite cells (SCs) are stem cells and the main players in skeletal muscle reconstruction. Since satellite cells are located near or in direct contact with blood vessels their niche is formed, inter alia, by endothelial cells. The cross-talk between satellite cells and endothelial cells determines quiescence or proliferation of these cells. However, little is known about the role of miRNA in these interactions. In the present study we identified miRNA that were up-regulated in SC-derived myoblasts treated with stromal derived factor-1 (SDF-1) and/or down-regulated in cells in which the expression of CXCR4 or CXCR7, that is, SDF-1 receptors, was silenced. SDF-1 is one of the important regulators of cell migration, mobilization, skeletal muscle regeneration, and angiogenesis. We hypothesized that selected miRNAs affect SC-derived myoblast fate and interactions with endothelial cells. We showed that miR-126a-3p inhibited both, myoblast migration and fusion. Moreover, the levels of Cxcl12, encoding SDF-1 and Ackr3, encoding CXCR7, were reduced by miR-126a-3p mimic. Interestingly, the miR-126a-3p mimic significantly decreased the level of numerous factors involved in myogenesis and the miR-126a-5p mimic increased the level of Vefga. Importantly, the treatment of endothelial cells with medium conditioned by miR-126-5p mimic transfected SC-derived myoblasts promoted tubulogenesis.

DOI: https://doi.org/10.1038/s41598-023-41626-z
J Appl Physiol (1985). 2023 Sep 14.

Short-term repeated human biopsy sampling contributes to changes in muscle morphology and higher outcome variability.

Douglas E Long, Alessandra J Mantuano, Amy L Confides, Benjamin F Miller, Philip A Kern, Timothy A Butterfield, Esther E Dupont-Versteegden.

  Changes in skeletal muscle are an important aspect of overall health. The collection of human muscle to study cellular and molecular processes for research requires a needle biopsy procedure which in itself can induce changes in the tissue. To investigate the effect of repeat tissue sampling, we collected skeletal muscle biopsy samples from vastus lateralis separated by 7 days. Cellular infiltrate, central nucleation, enlarged extracellular matrix and rounding of muscle fibers were used as indices to define muscle damage, and we found that 16/26 samples (61.5%) revealed at least 2 of these symptoms in the secondary biopsy. The presence of damage influenced outcome measures usually obtained in human biopsies. Damaged muscle showed an increase in the number of small fibers even though average fiber and fiber type specific cross-sectional area (CSA) were not different. This included higher numbers of embryonic myosin heavy chain positive fibers (p=0.001) as well as elevated satellite cell number (p=0.02) in the damaged areas and higher variability in satellite cell count in the total area (p=0.04). Collagen content was higher in damaged (p=0.0003) as well as non-damaged areas (p=0.05) of the muscle sections of the damaged compared to the non-damaged group. Myofibrillar protein and RNA fractional synthesis rates were not significantly different between the damaged compared to the non-damaged group. Results indicate that common outcomes as well as outcome variability in human muscle tissue are affected by previous biopsies. Therefore, the extent of potential damage should be assessed when performing repeated biopsies.

Keywords:  biopsy technique; histology; local anesthetic; muscle damage; skeletal muscle

DOI:  https://doi.org/10.1152/japplphysiol.00441.2023
Muscle Nerve. 2023 Sep 14.

Relative quantification of progressive changes in healthy and dysferlin-deficient mouse skeletal muscle proteomes.

Adriana E Golding, Wenping Li, Paul S Blank, Stephanie M Cologna, Joshua Zimmerberg.

  INTRODUCTION/AIMS: Individuals with dysferlinopathies, a group of genetic muscle diseases, experience delay in the onset of muscle weakness. The cause of this delay and subsequent muscle wasting are unknown, and there are currently no clinical interventions to limit or prevent muscle weakness. To better understand molecular drivers of dysferlinopathies, age-dependent changes in the proteomic profile of skeletal muscle (SM) in wild-type (WT) and dysferlin-deficient mice were identified.METHODS: Quadriceps were isolated from 6-, 18-, 42-, and 77-wk-old C57BL/6 (WT, Dysf+/+ ) and BLAJ (Dysf-/- ) mice (n = 3, 2 male/1 female or 1 male/2 female, 24 total). Whole-muscle proteomes were characterized using liquid chromatography-mass spectrometry with relative quantification using TMT10plex isobaric labeling. Principle component analysis was utilized to detect age-dependent proteomic differences over the lifespan of, and between, WT and dysferlin-deficient SM. The biological relevance of proteins with significant variation was established using Ingenuity Pathway Analysis.
RESULTS: Over 3200 proteins were identified between 6-, 18-, 42-, and 77-wk-old mice. In total, 46 proteins varied in aging WT SM (p < .01), while 365 varied in dysferlin-deficient SM. However, 569 proteins varied between aged-matched WT and dysferlin-deficient SM. Proteins with significant variation in expression across all comparisons followed distinct temporal trends.
DISCUSSION: Proteins involved in sarcolemma repair and regeneration underwent significant changes in SM over the lifespan of WT mice, while those associated with immune infiltration and inflammation were overly represented over the lifespan of dysferlin-deficient mice. The proteins identified herein are likely to contribute to our overall understanding of SM aging and dysferlinopathy disease progression.

Keywords:  dysferlin; dysferlinopathy; muscle wasting; proteome; skeletal muscle

DOI:  https://doi.org/10.1002/mus.27975
Stem Cell Res Ther. 2023 09 12. 14(1): 246

Injury-experienced satellite cells retain long-term enhanced regenerative capacity.

Jacopo Morroni, Anna Benedetti, Lorenza Esposito, Marco De Bardi, Giovanna Borsellino, Carles Sanchez Riera, Lorenzo Giordani, Marina Bouche, Biliana Lozanoska-Ochser.

  BACKGROUND: Inflammatory memory or trained immunity is a recently described process in immune and non-immune tissue resident cells, whereby previous exposure to inflammation mediators leads to a faster and stronger responses upon secondary challenge. Whether previous muscle injury is associated with altered responses to subsequent injury by satellite cells (SCs), the muscle stem cells, is not known.METHODS: We used a mouse model of repeated muscle injury, in which intramuscular cardiotoxin (CTX) injections were administered 50 days apart in order to allow for full recovery of the injured muscle before the second injury. The effect of prior injury on the phenotype, proliferation and regenerative potential of satellite cells following a second injury was examined in vitro and in vivo by immunohistochemistry, RT-qPCR and histological analysis.
RESULTS: We show that SCs isolated from muscle at 50 days post-injury (injury-experienced SCs (ieSCs)) enter the cell cycle faster and form bigger myotubes when cultured in vitro, compared to control SCs isolated from uninjured contralateral muscle. Injury-experienced SCs were characterized by the activation of the mTORC 1 signaling pathway, suggesting they are poised to activate sooner following a second injury. Consequently, upon second injury, SCs accumulate in greater numbers in muscle at 3 and 10 days after injury. These changes in SC phenotype and behavior were associated with accelerated muscle regeneration, as evidenced by an earlier appearance of bigger fibers and increased number of myonuclei per fiber at day 10 after the second injury.
CONCLUSIONS: Overall, we show that skeletal muscle injury has a lasting effect on SC function priming them to respond faster to a subsequent injury. The ieSCs have long-term enhanced regenerative properties that contribute to accelerated regeneration following a secondary challenge.

Keywords:  Inflammatory memory; Muscle regeneration; Repeated injury; Satellite cells

DOI:  https://doi.org/10.1186/s13287-023-03492-4
Am J Physiol Cell Physiol. 2023 Sep 11.

Redox state and altered pyruvate metabolism contribute to a dose-dependent metformin-induced lactate production of human myotubes.

Jennifer Maurer, Xinjie Zhao, Martin Irmler, Anders Gudiksen, Nanna S Pilmark, Qi Li, Thomas Goj, Johannes Beckers, Martin Hrabě de Angelis, Andreas Birkenfeld, Andreas Peter, Rainer Lehmann, Henriette Pilegaard, Kristian Karstoft, Guowang Xu, Cora Weigert.

  Metformin-induced glycolysis and lactate production can lead to acidosis as a life-threatening side effect, but slight increases in blood lactate levels in a physiological range were also reported in metformin-treated patients. However, how metformin increases systemic lactate concentrations is only partly understood. Because human skeletal muscle has a high capacity to produce lactate, the aim was to elucidate the dose-dependent regulation of metformin-induced lactate production and the potential contribution of skeletal muscle to blood lactate levels under metformin treatment. This was examined by using metformin treatment (16-776 μM) of primary human myotubes and by 17 days of metformin treatment in humans. As from 78 µM, metformin induced lactate production and secretion and glucose consumption. Investigating the cellular redox state by mitochondrial respirometry, we found metformin to inhibit the respiratory chain complex I (776 µM, p < 0.01) along with decreasing the [NAD+]:[NADH] ratio (776 µM, p < 0.001). RNA sequencing and phospho-immunoblot data indicate inhibition of pyruvate oxidation mediated through phosphorylation of the pyruvate dehydrogenase (PDH) complex (39 µM, p < 0.01). On the other hand, in human skeletal muscle, phosphorylation of PDH was not altered by metformin. Nonetheless, blood lactate levels were increased under metformin treatment (p < 0.05). In conclusion, the findings suggest that metformin-induced inhibition of pyruvate oxidation combined with altered cellular redox state, shifts the equilibrium of the lactate dehydrogenase (LDH) reaction leading to a dose-dependent lactate production in primary human myotubes.

Keywords:  Lactate; Metformin; Pyruvate dehydrogenase complex; Respiration; Skeletal Muscle

DOI:  https://doi.org/10.1152/ajpcell.00186.2023
Commun Biol. 2023 Sep 14. 6(1): 942

Speg interactions that regulate the stability of excitation-contraction coupling protein complexes in triads and dyads.

Chang Seok Lee, Sung Yun Jung, Rachel Sue Zhen Yee, Nadia H Agha, Jin Hong, Ting Chang, Lyle W Babcock, Jorie D Fleischman, Benjamin Clayton, Amy D Hanna, Christopher S Ward, Denise Lanza, Ayrea E Hurley, Pumin Zhang, Xander H T Wehrens, William R Lagor, George G Rodney, Susan L Hamilton.

Here we show that striated muscle preferentially expressed protein kinase α (Spegα) maintains cardiac function in hearts with Spegβ deficiency. Speg is required for stability of excitation-contraction coupling (ECC) complexes and interacts with esterase D (Esd), Cardiomyopathy-Associated Protein 5 (Cmya5), and Fibronectin Type III and SPRY Domain Containing 2 (Fsd2) in cardiac and skeletal muscle. Mice with a sequence encoding a V5/HA tag inserted into the first exon of the Speg gene (HA-Speg mice) display a >90% decrease in Spegβ but Spegα is expressed at ~50% of normal levels. Mice deficient in both Spegα and Speg β (Speg KO mice) develop a severe dilated cardiomyopathy and muscle weakness and atrophy, but HA-Speg mice display mild muscle weakness with no cardiac involvement. Spegα in HA-Speg mice suppresses Ca2+ leak, proteolytic cleavage of Jph2, and disruption of transverse tubules. Despite it's low levels, HA-Spegβ immunoprecipitation identified Esd, Cmya5 and Fsd2 as Spegβ binding partners that localize to triads and dyads to stabilize ECC complexes. This study suggests that Spegα and Spegβ display functional redundancy, identifies Esd, Cmya5 and Fsd2 as components of both cardiac dyads and skeletal muscle triads and lays the groundwork for the identification of new therapeutic targets for centronuclear myopathy.

DOI: https://doi.org/10.1038/s42003-023-05330-y
Nat Commun. 2023 Sep 11. 14(1): 5595

Deficiency of endothelial sirtuin1 in mice stimulates skeletal muscle insulin sensitivity by modifying the secretome.

Qiuxia Li, Quanjiang Zhang, Young-Rae Kim, Ravinder Reddy Gaddam, Julia S Jacobs, Markus M Bachschmid, Tsneem Younis, Zhiyong Zhu, Leonid Zingman, Barry London, Adam J Rauckhorst, Eric B Taylor, Andrew W Norris, Ajit Vikram, Kaikobad Irani.

Downregulation of endothelial Sirtuin1 (Sirt1) in insulin resistant states contributes to vascular dysfunction. Furthermore, Sirt1 deficiency in skeletal myocytes promotes insulin resistance. Here, we show that deletion of endothelial Sirt1, while impairing endothelial function, paradoxically improves skeletal muscle insulin sensitivity. Compared to wild-type mice, male mice lacking endothelial Sirt1 (E-Sirt1-KO) preferentially utilize glucose over fat, and have higher insulin sensitivity, glucose uptake, and Akt signaling in fast-twitch skeletal muscle. Enhanced insulin sensitivity of E-Sirt1-KO mice is transferrable to wild-type mice via the systemic circulation. Endothelial Sirt1 deficiency, by inhibiting autophagy and activating nuclear factor-kappa B signaling, augments expression and secretion of thymosin beta-4 (Tβ4) that promotes insulin signaling in skeletal myotubes. Thus, unlike in skeletal myocytes, Sirt1 deficiency in the endothelium promotes glucose homeostasis by stimulating skeletal muscle insulin sensitivity through a blood-borne mechanism, and augmented secretion of Tβ4 by Sirt1-deficient endothelial cells boosts insulin signaling in skeletal muscle cells.

DOI: https://doi.org/10.1038/s41467-023-41351-1
Cell Prolif. 2023 Sep 13. e13545

Bulk and single-cell alternative splicing analyses reveal roles of TRA2B in myogenic differentiation.

Genghua Chen, Jiahui Chen, Lin Qi, Yunqian Yin, Zetong Lin, Huaqiang Wen, Shuai Zhang, Chuanyun Xiao, Semiu Folaniyi Bello, Xiquan Zhang, Qinghua Nie, Wen Luo.

Alternative splicing (AS) disruption has been linked to disorders of muscle development, as well as muscular atrophy. However, the precise changes in AS patterns that occur during myogenesis are not well understood. Here, we employed isoform long-reads RNA-seq (Iso-seq) and single-cell RNA-seq (scRNA-seq) to investigate the AS landscape during myogenesis. Our Iso-seq data identified 61,146 full-length isoforms representing 11,682 expressed genes, of which over 52% were novel. We identified 38,022 AS events, with most of these events altering coding sequences and exhibiting stage-specific splicing patterns. We identified AS dynamics in different types of muscle cells through scRNA-seq analysis, revealing genes essential for the contractile muscle system and cytoskeleton that undergo differential splicing across cell types. Gene-splicing analysis demonstrated that AS acts as a regulator, independent of changes in overall gene expression. Two isoforms of splicing factor TRA2B play distinct roles in myogenic differentiation by triggering AS of TGFBR2 to regulate canonical TGF-β signalling cascades differently. Our study provides a valuable transcriptome resource for myogenesis and reveals the complexity of AS and its regulation during myogenesis.

DOI: https://doi.org/10.1111/cpr.13545
Cell Rep. 2023 Sep 12. pii: S2211-1247(23)01132-4. [Epub ahead of print]42(9): 113120

MATR3 is an endogenous inhibitor of DUX4 in FSHD muscular dystrophy.

Valeria Runfola, Roberto Giambruno, Claudia Caronni, Maria Pannese, Annapaola Andolfo, Davide Gabellini.

  Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common neuromuscular disorders and has no cure. Due to an unknown molecular mechanism, FSHD displays overlapping manifestations with the neurodegenerative disease amyotrophic lateral sclerosis (ALS). FSHD is caused by aberrant gain of expression of the transcription factor double homeobox 4 (DUX4), which triggers a pro-apoptotic transcriptional program resulting in inhibition of myogenic differentiation and muscle wasting. Regulation of DUX4 activity is poorly known. We identify Matrin 3 (MATR3), whose mutation causes ALS and dominant distal myopathy, as a cellular factor controlling DUX4 expression and activity. MATR3 binds to the DUX4 DNA-binding domain and blocks DUX4-mediated gene expression, rescuing cell viability and myogenic differentiation of FSHD muscle cells, without affecting healthy muscle cells. Finally, we characterize a shorter MATR3 fragment that is necessary and sufficient to directly block DUX4-induced toxicity to the same extent as the full-length protein. Collectively, our data suggest MATR3 as a candidate for developing a treatment for FSHD.

Keywords:  ALS; CP: Developmental biology; DUX4; FSHD; cell toxicity; gene regulation; muscle differentiation

DOI:  https://doi.org/10.1016/j.celrep.2023.113120
PLoS One. 2023 ;18(9): e0291462

The combination of quercetin and leucine synergistically improves grip strength by attenuating muscle atrophy by multiple mechanisms in mice exposed to cisplatin.

Te-Hsing Hsu, Ting-Jian Wu, Yu-An Tai, Chin-Shiu Huang, Jiunn-Wang Liao, Shu-Lan Yeh.

Both quercetin and leucine have been shown to exert moderately beneficial effects in preventing muscle atrophy induced by cancers or chemotherapy. However, the combined effects of quercetin and leucine, as well as the possible underlying mechanisms against cisplatin (CDDP)-induced muscle atrophy and cancer-related fatigue (CRF) remain unclear. To investigate the issues, male BALB/c mice were randomly assigned to the following groups for 9 weeks: Control, CDDP (3 mg/kg/week), CDDP+Q (quercetin 200 mg/kg/day administrated by gavage), CDDP+LL (a diet containing 0.8% leucine), CDDP+Q+LL, CDDP+HL (a diet containing 1.6% leucine), and CDDP+Q+HL. The results showed that quercetin in combination with LL or HL synergistically or additively attenuated CDDP-induced decreases in maximum grip strength, fat and muscle mass, muscle fiber size and MyHC level in muscle tissues. However, the combined effects on locomotor activity were less than additive. The combined treatments decreased the activation of the Akt/FoxO1/atrogin-1/MuRF1 signaling pathway (associated with muscle protein degradation), increased the activation of the mTOR and E2F-1 signaling pathways (associated with muscle protein synthesis and cell cycle/growth, respectively). The combined effects on signaling molecules present in muscle tissues were only additive or less. In addition, only Q+HL significantly increased glycogen levels compared to the CDDP group, while the combined treatments considerably decreased CDDP-induced proinflammatory cytokine and MCP-1 levels in the triceps muscle. Using tumor-bearing mice, we demonstrated that the combined treatments did not decrease the anticancer effect of CDDP. In conclusion, this study suggests that the combination of quercetin and leucine enhanced the suppressed effects on CDDP-induced muscle weakness and CRF through downregulating muscle atrophy and upregulating the glycogen level in muscle tissues without compromising the anticancer effect of CDDP. Multiple mechanisms, including regulation of several signaling pathways and decrease in proinflammatory mediator levels in muscles may contributed to the enhanced protective effect of the combined treatments on muscle atrophy.

DOI: https://doi.org/10.1371/journal.pone.0291462
J Physiol. 2023 Sep 12.

Skeletal muscle mitochondria in strength athletes: meeting energy needs with mitochondrial morphological changes.

Alyse L Lodigiani, Joseph C Morrison.



Keywords:  Olympic weightlifting; mitochondria; mitochondrial morphology; powerlifting; strength training; transmission electron microscopy

DOI:  https://doi.org/10.1113/JP285345
Am J Physiol Cell Physiol. 2023 Sep 11.

Skeletal Muscle-derived FSTL1 Starting up Angiogenesis by Regulating Endothelial Junction via Activating Src Pathway Can be Upregulated by Hydrogen Sulfide.

Meng-Yao Li, Ru-Pan Gao, Qi Zhu, Ying Chen, Bei-Bei Tao, Yi-Chun Zhu.

  Hydrogen sulfide (H2S) promotes microangiogenesis and revascularization after ischemia. Neovascularization starts with the destruction of intercellular junctions and is accompanied by various endothelial cell angiogenic behaviors. Follistatin-like 1 (FSTL1) is a cardiovascular-protective myokine that works against ischemic injury. The present study examined whether FSTL1 was involved in H2S-induced angiogenesis and explored the underlying molecular mechanism. We observed that H2S accelerated blood perfusion after ischemia in the mouse hindlimb ischemia model. Western blot analysis showed that H2S stabilized FSTL1 transcript and increased FSTL1 and Human antigen R (HuR) levels in skeletal muscle. RNA interference HuR significantly inhibited the H2S-promoted increase in FSTL1 levels. Exogenous FSTL1 promoted the wound healing migration of human umbilical vein endothelial cell (HUVEC) and increased monolayer endothelial barrier permeability. Immunostaining showed that FSTL1 increased inter-endothelial gap formation and decreased VE-Cadherin, Occludin, Connexin-43, and Claudin-5 expression. In addition, FSTL1 significantly increased the phosphorylation of Src and VEGFR2. However, that the Src inhibitor, not the VEGFR2 inhibitor, could block FSTL1-induced effects in angiogenesis. In conclusion, we demonstrated that H2S could upregulate the expression of FSTL1 by increasing the HuR levels in skeletal muscle, and paracrine FSTL1 could initiate angiogenesis by opening intercellular junctions via the Src signaling pathway.

Keywords:  Angiogenesis; Endothelial function; FSTL1; H2S; Src tyrosine phosphorylation

DOI:  https://doi.org/10.1152/ajpcell.00219.2023