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Skeletal muscle atrophy is a morbidity and mortality risk factor that happens with disuse, chronic disease, and aging. The tissue remodeling that happens during recovery from atrophy or injury involves changes in different cell types such as muscle fibers, and satellite and immune cells. Here, we show that the previously uncharacterized gene and protein Zfp697 is a damage-induced regulator of muscle remodeling. Zfp697/ZNF697 expression is transiently elevated during recovery from muscle atrophy or injury in mice and humans. Sustained Zfp697 expression in mouse muscle leads to a gene expression signature of chemokine secretion, immune cell recruitment, and extracellular matrix remodeling. Notably, although Zfp697 is expressed in several cell types in skeletal muscle, myofiber-specific Zfp697 genetic ablation in mice is sufficient to hinder the inflammatory and regenerative response to muscle injury, compromising functional recovery. We show that Zfp697 is an essential mediator of the interferon gamma response in muscle cells and that it functions primarily as an RNA-interacting protein, with a very high number of miRNA targets. This work identifies Zfp697 as an integrator of cell-cell communication necessary for tissue remodeling and regeneration.
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Músculo Esquelético , Proteínas de Unión al ARN , Animales , Ratones , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Humanos , Inflamación/metabolismo , Inflamación/patología , Inflamación/genética , Ratones Noqueados , Atrofia Muscular/metabolismo , Atrofia Muscular/genética , Atrofia Muscular/patología , MicroARNs/genética , MicroARNs/metabolismo , Ratones Endogámicos C57BL , Interferón gamma/metabolismoRESUMEN
In cell biology, ribosomal RNA (rRNA) 2'O-methyl (2'-O-Me) is the most prevalent posttranscriptional chemical modification contributing to ribosome heterogeneity. The modification involves a family of small nucleolar RNAs (snoRNAs) and is specified by box C/D snoRNAs (SNORDs). Given the importance of ribosome biogenesis for skeletal muscle growth, we asked if rRNA 2'-O-Me in nascent ribosomes synthesized in response to a growth stimulus is an unrecognized mode of ribosome heterogeneity in muscle. To determine the pattern and dynamics of 2'-O-Me rRNA, we used a sequencing-based profiling method called RiboMeth-seq (RMS). We applied this method to tissue-derived rRNA of skeletal muscle and rRNA specifically from the muscle fiber using an inducible myofiber-specific RiboTag mouse in sedentary and mechanically overloaded conditions. These analyses were complemented by myonuclear-specific small RNA sequencing to profile SNORDs and link the rRNA epitranscriptome to known regulatory elements generated within the muscle fiber. We demonstrate for the first time that mechanical overload of skeletal muscle 1) induces decreased 2'-O-Me at a subset of skeletal muscle rRNA and 2) alters the SNORD profile in isolated myonuclei. These findings point to a transient diversification of the ribosome pool via 2'-O-Me during growth and adaptation in skeletal muscle. These findings suggest changes in ribosome heterogeneity at the 2'-O-Me level during muscle hypertrophy and lay the foundation for studies investigating the functional implications of these newly identified "growth-induced" ribosomes.NEW & NOTEWORTHY Ribosomal RNAs (rRNAs) are posttranscriptionally modified by 2'O-methyl (2'-O-Me). This study applied RiboMeth-seq (RMS) to detect changes in 2'-O-Me levels during skeletal muscle hypertrophy, uncovering transient diversification of the ribosome pool in skeletal muscle fibers. This work implies a role for ribosome heterogeneity in skeletal muscle growth and adaptation.
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Fibras Musculares Esqueléticas , ARN Ribosómico , ARN Nucleolar Pequeño , Ribosomas , Transcriptoma , Animales , Ribosomas/metabolismo , Ribosomas/genética , ARN Ribosómico/genética , ARN Ribosómico/metabolismo , Ratones , Fibras Musculares Esqueléticas/metabolismo , ARN Nucleolar Pequeño/genética , ARN Nucleolar Pequeño/metabolismo , Hipertrofia/genética , Masculino , Ratones Endogámicos C57BL , Procesamiento Postranscripcional del ARN , Músculo Esquelético/metabolismo , Epigénesis GenéticaRESUMEN
Molecular control of recovery after exercise in muscle is temporally dynamic. A time course of biopsies around resistance exercise (RE) combined with -omics is necessary to better comprehend the molecular contributions of skeletal muscle adaptation in humans. Vastus lateralis biopsies before and 30 minutes, 3-, 8-, and 24-hours after acute RE were collected. A time-point matched biopsy-only group was also included. RNA-sequencing defined the transcriptome while DNA methylomics and computational approaches complemented these data. The post-RE time course revealed: 1) DNA methylome responses at 30 minutes corresponded to upregulated genes at 3 hours, 2) a burst of translation- and transcription-initiation factor-coding transcripts occurred between 3 and 8 hours, 3) global gene expression peaked at 8 hours, 4) ribosome-related genes dominated the mRNA landscape between 8 and 24 hours, 5) methylation-regulated MYC was a highly influential transcription factor throughout the 24-hour recovery and played a primary role in ribosome-related mRNA levels between 8 and 24 hours. The influence of MYC in human muscle adaptation was strengthened by transcriptome information from acute MYC overexpression in mouse muscle. To test whether MYC was sufficient for hypertrophy, we generated a muscle fiber-specific doxycycline inducible model of pulsatile MYC induction. Periodic 48-hour pulses of MYC over 4 weeks resulted in higher muscle mass and fiber size in the soleus of adult female mice. Collectively, we present a temporally resolved resource for understanding molecular adaptations to RE in muscle and reveal MYC as a regulator of RE-induced mRNA levels and hypertrophy.
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OBJECTIVE: Skeletal muscle plasticity and remodeling are critical for adapting tissue function to use, disuse, and regeneration. The aim of this study was to identify genes and molecular pathways that regulate the transition from atrophy to compensatory hypertrophy or recovery from injury. Here, we have used a mouse model of hindlimb unloading and reloading, which causes skeletal muscle atrophy, and compensatory regeneration and hypertrophy, respectively. METHODS: We analyzed mouse skeletal muscle at the transition from hindlimb unloading to reloading for changes in transcriptome and extracellular fluid proteome. We then used qRT-PCR, immunohistochemistry, and bulk and single-cell RNA sequencing data to determine Mustn1 gene and protein expression, including changes in gene expression in mouse and human skeletal muscle with different challenges such as exercise and muscle injury. We generated Mustn1-deficient genetic mouse models and characterized them in vivo and ex vivo with regard to muscle function and whole-body metabolism. We isolated smooth muscle cells and functionally characterized them, and performed transcriptomics and proteomics analysis of skeletal muscle and aorta of Mustn1-deficient mice. RESULTS: We show that Mustn1 (Musculoskeletal embryonic nuclear protein 1, also known as Mustang) is highly expressed in skeletal muscle during the early stages of hindlimb reloading. Mustn1 expression is transiently elevated in mouse and human skeletal muscle in response to intense exercise, resistance exercise, or injury. We find that Mustn1 expression is highest in smooth muscle-rich tissues, followed by skeletal muscle fibers. Muscle from heterozygous Mustn1-deficient mice exhibit differences in gene expression related to extracellular matrix and cell adhesion, compared to wild-type littermates. Mustn1-deficient mice have normal muscle and aorta function and whole-body glucose metabolism. We show that Mustn1 is secreted from smooth muscle cells, and that it is present in arterioles of the muscle microvasculature and in muscle extracellular fluid, particularly during the hindlimb reloading phase. Proteomics analysis of muscle from Mustn1-deficient mice confirms differences in extracellular matrix composition, and female mice display higher collagen content after chemically induced muscle injury compared to wild-type littermates. CONCLUSIONS: We show that, in addition to its previously reported intracellular localization, Mustn1 is a microprotein secreted from smooth muscle cells into the muscle extracellular space. We explore its role in muscle ECM deposition and remodeling in homeostasis and upon muscle injury. The role of Mustn1 in fibrosis and immune infiltration upon muscle injury and dystrophies remains to be investigated, as does its potential for therapeutic interventions.
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Micropéptidos , Músculo Esquelético , Animales , Femenino , Humanos , Ratones , Matriz Extracelular/metabolismo , Hipertrofia/metabolismo , Músculo Esquelético/metabolismo , Atrofia Muscular/metabolismo , Miocitos del Músculo Liso/metabolismoRESUMEN
Exercise training reduces the incidence of several cancers, but the mechanisms underlying these effects are not fully understood. Exercise training can affect the spleen function, which controls the hematopoiesis and immune response. Analyzing different cancer models, we identified that 4T1, LLC, and CT26 tumor-bearing mice displayed enlarged spleen (splenomegaly), and exercise training reduced spleen mass toward control levels in two of these models (LLC and CT26). Exercise training also slowed tumor growth in melanoma B16F10, colon tumor 26 (CT26), and Lewis lung carcinoma (LLC) tumor-bearing mice, with minor effects in mammary carcinoma 4T1, MDA-MB-231, and MMTV-PyMT mice. In silico analyses using transcriptome profiles derived from these models revealed that platelet factor 4 (Pf4) is one of the main upregulated genes associated with splenomegaly during cancer progression. To understand whether exercise training would modulate the expression of these genes in the tumor and spleen, we investigated particularly the CT26 model, which displayed splenomegaly and had a clear response to the exercise training effects. RT-qPCR analysis confirmed that trained CT26 tumor-bearing mice had decreased Pf4 mRNA levels in both the tumor and spleen when compared to untrained CT26 tumor-bearing mice. Furthermore, exercise training specifically decreased Pf4 mRNA levels in the CT26 tumor cells. Aspirin treatment did not change tumor growth, splenomegaly, and tumor Pf4 mRNA levels, confirming that exercise decreased non-platelet Pf4 mRNA levels. Finally, tumor Pf4 mRNA levels are deregulated in The Cancer Genome Atlas Program (TCGA) samples and predict survival in multiple cancer types. This highlights the potential therapeutic value of exercise as a complementary approach to cancer treatment and underscores the importance of understanding the exercise-induced transcriptional changes in the spleen for the development of novel cancer therapies.
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Carcinoma Pulmonar de Lewis , Neoplasias del Colon , Ejercicio Físico , Factor Plaquetario 4 , Animales , Ratones , Inhibidores de la Angiogénesis , Carcinoma Pulmonar de Lewis/genética , Carcinoma Pulmonar de Lewis/terapia , Línea Celular Tumoral , Neoplasias del Colon/patología , Factores Inmunológicos , Ratones Endogámicos BALB C , Factor Plaquetario 4/genética , ARN Mensajero , Esplenomegalia/metabolismo , Ejercicio Físico/fisiologíaAsunto(s)
Andrógenos , Neoplasias de la Próstata , Masculino , Humanos , Antagonistas de Andrógenos , Sirtuina 1 , Músculos , TestosteronaRESUMEN
Muscular atrophy is a mortality risk factor that happens with disuse, chronic disease, and aging. Recovery from atrophy requires changes in several cell types including muscle fibers, and satellite and immune cells. Here we show that Zfp697/ZNF697 is a damage-induced regulator of muscle regeneration, during which its expression is transiently elevated. Conversely, sustained Zfp697 expression in mouse muscle leads to a gene expression signature of chemokine secretion, immune cell recruitment, and extracellular matrix remodeling. Myofiber-specific Zfp697 ablation hinders the inflammatory and regenerative response to muscle injury, compromising functional recovery. We uncover Zfp697 as an essential interferon gamma mediator in muscle cells, interacting primarily with ncRNAs such as the pro-regenerative miR-206. In sum, we identify Zfp697 as an integrator of cell-cell communication necessary for tissue regeneration.
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Different formative pluripotent stem cells harboring similar functional properties have been recently established to be lineage neutral and germline competent yet have distinct molecular identities. Here, we show that WNT/ß-catenin signaling activation sustains transient mouse epiblast-like cells as epiblast-like stem cells (EpiLSCs). EpiLSCs display metastable formative pluripotency with bivalent cellular energy metabolism and unique transcriptomic features and chromatin accessibility. We develop single-cell stage label transfer (scSTALT) to study the formative pluripotency continuum and reveal that EpiLSCs recapitulate a unique developmental period in vivo, filling the gap of the formative pluripotency continuum between other published formative stem cells. WNT/ß-catenin signaling activation counteracts differentiation effects of activin A and bFGF by preventing complete dissolution of naive pluripotency regulatory network. Moreover, EpiLSCs have direct competence toward germline specification, which is further matured by an FGF receptor inhibitor. Our EpiLSCs can serve as an in vitro model for mimicking and studying early post-implantation development and pluripotency transition.
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Células Madre Pluripotentes , Vía de Señalización Wnt , Animales , Ratones , beta Catenina , Diferenciación Celular , Células Germinativas , Estratos GerminativosRESUMEN
Mitochondria are the main consumers of oxygen within the cell. How mitochondria sense oxygen levels remains unknown. Here we show an oxygen-sensitive regulation of TFAM, an activator of mitochondrial transcription and replication, whose alteration is linked to tumours arising in the von Hippel-Lindau syndrome. TFAM is hydroxylated by EGLN3 and subsequently bound by the von Hippel-Lindau tumour-suppressor protein, which stabilizes TFAM by preventing mitochondrial proteolysis. Cells lacking wild-type VHL or in which EGLN3 is inactivated have reduced mitochondrial mass. Tumorigenic VHL variants leading to different clinical manifestations fail to bind hydroxylated TFAM. In contrast, cells harbouring the Chuvash polycythaemia VHLR200W mutation, involved in hypoxia-sensing disorders without tumour development, are capable of binding hydroxylated TFAM. Accordingly, VHL-related tumours, such as pheochromocytoma and renal cell carcinoma cells, display low mitochondrial content, suggesting that impaired mitochondrial biogenesis is linked to VHL tumorigenesis. Finally, inhibiting proteolysis by targeting LONP1 increases mitochondrial content in VHL-deficient cells and sensitizes therapy-resistant tumours to sorafenib treatment. Our results offer pharmacological avenues to sensitize therapy-resistant VHL tumours by focusing on the mitochondria.
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Carcinoma de Células Renales , Neoplasias Renales , Enfermedad de von Hippel-Lindau , Proteasas ATP-Dependientes , Carcinoma de Células Renales/genética , Humanos , Neoplasias Renales/genética , Proteínas Mitocondriales , Biogénesis de Organelos , Oxígeno , Enfermedad de von Hippel-Lindau/genéticaRESUMEN
The peroxisome proliferator-activated receptor γ coactivator-1α (Ppargc1a) gene encodes several PGC-1α isoforms that regulate mitochondrial bioenergetics and cellular adaptive processes. Expressing specific PGC-1α isoforms in mice can confer protection in different disease models. This SnapShot summarizes how regulation of Ppargc1a transcription, splicing, translation, protein stability, and activity underlies its multifaceted functions. To view this SnapShot, open or download the PDF.
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Regulación de la Expresión Génica , Mitocondrias , Animales , Biología , Metabolismo Energético , Ratones , Mitocondrias/genética , Mitocondrias/metabolismo , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/genética , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismoRESUMEN
Endurance exercise promotes skeletal muscle vascularization, oxidative metabolism, fiber-type switching, and neuromuscular junction integrity. Importantly, the metabolic and contractile properties of the muscle fiber must be coupled to the identity of the innervating motor neuron (MN). Here, we show that muscle-derived neurturin (NRTN) acts on muscle fibers and MNs to couple their characteristics. Using a muscle-specific NRTN transgenic mouse (HSA-NRTN) and RNA sequencing of MN somas, we observed that retrograde NRTN signaling promotes a shift toward a slow MN identity. In muscle, NRTN increased capillary density and oxidative capacity and induced a transcriptional reprograming favoring fatty acid metabolism over glycolysis. This combination of effects on muscle and MNs makes HSA-NRTN mice lean with remarkable exercise performance and motor coordination. Interestingly, HSA-NRTN mice largely recapitulate the phenotype of mice with muscle-specific expression of its upstream regulator PGC-1É1. This work identifies NRTN as a myokine that couples muscle oxidative capacity to slow MN identity.
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Neuronas Motoras , Neurturina , Animales , Ratones , Ratones Transgénicos , Neuronas Motoras/metabolismo , Músculo Esquelético/metabolismo , Neurturina/genética , Neurturina/metabolismo , Neurturina/farmacología , Estrés OxidativoRESUMEN
Proprioceptive neurons (PNs) are essential for the proper execution of all our movements by providing muscle sensory feedback to the central motor network. Here, using deep single cell RNAseq of adult PNs coupled with virus and genetic tracings, we molecularly identify three main types of PNs (Ia, Ib and II) and find that they segregate into eight distinct subgroups. Our data unveil a highly sophisticated organization of PNs into discrete sensory input channels with distinct spatial distribution, innervation patterns and molecular profiles. Altogether, these features contribute to finely regulate proprioception during complex motor behavior. Moreover, while Ib- and II-PN subtypes are specified around birth, Ia-PN subtypes diversify later in life along with increased motor activity. We also show Ia-PNs plasticity following exercise training, suggesting Ia-PNs are important players in adaptive proprioceptive function in adult mice.
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Retroalimentación Sensorial/fisiología , Ganglios Espinales/metabolismo , Neuronas Motoras/metabolismo , Propiocepción/fisiología , Células Receptoras Sensoriales/metabolismo , Animales , Calbindina 1/genética , Calbindina 1/metabolismo , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Proteínas Co-Represoras/genética , Proteínas Co-Represoras/metabolismo , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/metabolismo , Subunidad alfa 3 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 3 del Factor de Unión al Sitio Principal/metabolismo , Ganglios Espinales/citología , Expresión Génica , Proteínas con Dominio LIM/genética , Proteínas con Dominio LIM/metabolismo , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Neuronas Motoras/clasificación , Neuronas Motoras/citología , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Condicionamiento Físico Animal , Células Receptoras Sensoriales/clasificación , Células Receptoras Sensoriales/citología , Análisis de la Célula Individual , Médula Espinal/citología , Médula Espinal/metabolismoRESUMEN
The molecular mechanisms underlying skeletal muscle mitochondrial adaptations induced by aerobic exercise (AE) are not fully understood. We have previously shown that AE induces mitochondrial adaptations in cardiac muscle, mediated by sympathetic stimulation. Since direct sympathetic innervation of neuromuscular junctions influences skeletal muscle homeostasis, we tested the hypothesis that ß2-adrenergic receptor (ß2-AR)-mediated sympathetic activation induces mitochondrial adaptations to AE in skeletal muscle. Male FVB mice were subjected to a single bout of AE on a treadmill (80% Vmax, 60 min) under ß2-AR blockade with ICI 118,551 (ICI) or vehicle, and parameters of mitochondrial function and morphology/dynamics were evaluated. An acute bout of AE significantly increased maximal mitochondrial respiration in tibialis anterior (TA) isolated fiber bundles, which was prevented by ß2-AR blockade. This increased mitochondrial function after AE was accompanied by a change in mitochondrial morphology towards fusion, associated with increased Mfn1 protein expression and activity. ß2-AR blockade fully prevented the increase in Mfn1 activity and reduced mitochondrial elongation. To determine the mechanisms involved in mitochondrial modulation by ß2-AR activation in skeletal muscle during AE, we used C2C12 myotubes, treated with the non-selective ß-AR agonist isoproterenol (ISO) in the presence of the specific ß2-AR antagonist ICI or during protein kinase A (PKA) and Gαi protein blockade. Our in vitro data show that ß-AR activation significantly increases mitochondrial respiration in myotubes, and this response was dependent on ß2-AR activation through a Gαs-PKA signaling cascade. In conclusion, we provide evidence for AE-induced ß2-AR activation as a major mechanism leading to alterations in mitochondria function and morphology/dynamics. ß2-AR signaling is thus a key-signaling pathway that contributes to skeletal muscle plasticity in response to exercise.
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Mitocondrias/metabolismo , Músculo Esquelético/metabolismo , Condicionamiento Físico Animal , Receptores Adrenérgicos beta 2/metabolismo , Transducción de Señal , Animales , Línea Celular , Respiración de la Célula , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Masculino , Ratones , Dinámicas MitocondrialesRESUMEN
Increasing exercise capacity promotes healthy aging and is strongly associated with lower mortality rates. In this study, we analyzed skeletal muscle transcriptomics coupled to exercise performance in humans and rats to dissect the inherent and response components of aerobic exercise capacity. Using rat models selected for intrinsic and acquired aerobic capacity, we determined that the high aerobic capacity muscle transcriptome is associated with pathways for tissue oxygenation and vascularization. Conversely, the low capacity muscle transcriptome indicated immune response and metabolic dysfunction. Low response to training was associated with an inflammatory signature and revealed a potential link to circadian rhythm. Next, we applied bioinformatics tools to predict potential secreted factors (myokines). The predicted secretome profile for exercise capacity highlighted circulatory factors involved in lipid metabolism and the exercise response secretome was associated with extracellular matrix remodelling. Lastly, we utilized human muscle mitochondrial respiration and transcriptomics data to explore molecular mediators of exercise capacity and response across species. Human transcriptome comparison highlighted epigenetic mechanisms linked to exercise capacity and the damage repair for response. Overall, our findings from this cross-species transcriptome analysis of exercise capacity and response establish a foundation for future studies on the mechanisms that link exercise and health.
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Ritmo Circadiano , Tolerancia al Ejercicio , Regulación de la Expresión Génica , Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Condicionamiento Físico Animal , Transcriptoma , Animales , Humanos , Inflamación/genética , Masculino , Proteínas Musculares/genética , RatasRESUMEN
OBJECTIVE: We tested the hypothesis that exercise training would attenuate metabolic impairment in a model of severe cancer cachexia. METHODS: We used multiple in vivo and in vitro methods to explore the mechanisms underlying the beneficial effects induced by exercise training in tumor-bearing rats. RESULTS: Exercise training improved running capacity, prolonged lifespan, reduced oxidative stress, and normalized muscle mass and contractile function in tumor-bearing rats. An unbiased proteomic screening revealed COP9 signalosome complex subunit 2 (COPS2) as one of the most downregulated proteins in skeletal muscle at the early stage of cancer cachexia. Exercise training normalized muscle COPS2 protein expression in tumor-bearing rats and mice. Lung cancer patients with low endurance capacity had low muscle COPS2 protein expression as compared to age-matched control subjects. To test whether decrease in COPS2 protein levels could aggravate or be an intrinsic compensatory mechanism to protect myotubes from cancer effects, we performed experiments in vitro using primary myotubes. COPS2 knockdown in human myotubes affected multiple cellular pathways, including regulation of actin cytoskeleton. Incubation of cancer-conditioned media in mouse myotubes decreased F-actin expression, which was partially restored by COPS2 knockdown. Direct repeat 4 (DR4) response elements have been shown to positively regulate gene expression. COPS2 overexpression decreased the DR4 activity in mouse myoblasts, and COPS2 knockdown inhibited the effects of cancer-conditioned media on DR4 activity. CONCLUSIONS: These studies demonstrated that exercise training may be an important adjuvant therapy to counteract cancer cachexia and uncovered novel mechanisms involving COPS2 to regulate myotube homeostasis in cancer cachexia.
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Complejo del Señalosoma COP9/metabolismo , Músculo Esquelético/metabolismo , Neoplasias/metabolismo , Estrés Oxidativo , Condicionamiento Físico Animal , Proteínas Represoras/metabolismo , Animales , Biomarcadores , Complejo del Señalosoma COP9/genética , Caquexia/etiología , Caquexia/metabolismo , Línea Celular Tumoral , Citocinas/metabolismo , Modelos Animales de Enfermedad , Metabolismo Energético , Técnicas de Silenciamiento del Gen , Humanos , Masculino , Ratones , Fibras Musculares Esqueléticas/metabolismo , Atrofia Muscular/etiología , Atrofia Muscular/metabolismo , Mioblastos/metabolismo , Neoplasias/complicaciones , Oxidación-Reducción , Proteómica/métodos , Ratas , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF/genética , Receptores del Ligando Inductor de Apoptosis Relacionado con TNF/metabolismo , Proteínas Represoras/genética , Transducción de SeñalRESUMEN
OBJECTIVE: The liver is regularly exposed to changing metabolic and inflammatory environments. It must sense and adapt to metabolic need while balancing resources required to protect itself from insult. Peroxisome proliferator activated receptor gamma coactivator-1 alpha (PGC-1α) is a transcriptional coactivator expressed as multiple, alternatively spliced variants transcribed from different promoters that coordinate metabolic adaptation and protect against inflammation. It is not known how PGC-1α integrates extracellular signals to balance metabolic and anti-inflammatory outcomes. METHODS: Primary mouse hepatocytes were used to evaluate the role(s) of different PGC-1α proteins in regulating hepatic metabolism and inflammatory signaling downstream of tumor necrosis factor alpha (TNFα). Gene expression and signaling analysis were combined with biochemical measurement of apoptosis using gain- and loss-of-function in vitro and in vivo. RESULTS: Hepatocytes expressed multiple isoforms of PGC-1α, including PGC-1α4, which microarray analysis showed had common and isoform-specific functions linked to metabolism and inflammation compared with canonical PGC-1α1. Whereas PGC-1α1 primarily impacted gene programs of nutrient metabolism and mitochondrial biology, TNFα signaling showed several pathways related to innate immunity and cell death downstream of PGC-1α4. Gain- and loss-of-function models illustrated that PGC-1α4 uniquely enhanced expression of anti-apoptotic gene programs and attenuated hepatocyte apoptosis in response to TNFα or lipopolysaccharide (LPS). This was in contrast to PGC-1α1, which decreased the expression of a wide inflammatory gene network but did not prevent hepatocyte death in response to cytokines. CONCLUSIONS: PGC-1α variants have distinct, yet complementary roles in hepatic responses to metabolism and inflammation, and we identify PGC-1α4 as an important mitigator of apoptosis.
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Apoptosis , Hepatocitos/metabolismo , Inflamación/metabolismo , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Animales , Línea Celular , Femenino , Hepatocitos/patología , Inflamación/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/deficiencia , Isoformas de Proteínas/deficiencia , Isoformas de Proteínas/metabolismoRESUMEN
BACKGROUND: Gene expression is an important process underpinning the acute and chronic adaptive response to resistance exercise (RE) training. PURPOSE: To investigate the effect of training status on vastus lateralis muscle global transcriptome at rest and following acute RE. METHODS: Muscle biopsies of nine young men (age: 26(2) years; body mass: 69(9) kg; height 172(6) cm) who undertook RE training for 10 weeks were collected pre and 24 h post-RE in the untrained (W1) and trained (W10) states and analysed using microarray. Tests of differential expression were conducted for rested and after RE contrasts in both training states. To control for false discovery rate (FDR), multiple testing correction was performed at a cut-off of FDR < 0.05. RESULTS: Unaccustomed RE (at W1) upregulated muscle gene transcripts related to stress (e.g., heat shock proteins), damage and inflammation, structural remodelling, protein turnover and increased translational capacity. Trained muscles (at W10) showed changes in the transcriptome signature regarding the regulation of energy metabolism, favouring a more oxidative one, upregulated antioxidant- and immune-related genes/terms, and gene transcripts related to the cytoskeleton and extracellular matrix, muscle contraction, development and growth. CONCLUSIONS: These results highlight that chronic repetition of RE changes muscle transcriptome response towards a more refined response to RE-induced stress.
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Músculo Esquelético/metabolismo , Entrenamiento de Fuerza , Estrés Fisiológico , Transcriptoma , Adulto , Humanos , Masculino , Músculo Esquelético/anatomía & histología , Músculo Esquelético/fisiologíaRESUMEN
The role of tryptophan-kynurenine metabolism in psychiatric disease is well established, but remains less explored in peripheral tissues. Exercise training activates kynurenine biotransformation in skeletal muscle, which protects from neuroinflammation and leads to peripheral kynurenic acid accumulation. Here we show that kynurenic acid increases energy utilization by activating G protein-coupled receptor Gpr35, which stimulates lipid metabolism, thermogenic, and anti-inflammatory gene expression in adipose tissue. This suppresses weight gain in animals fed a high-fat diet and improves glucose tolerance. Kynurenic acid and Gpr35 enhance Pgc-1α1 expression and cellular respiration, and increase the levels of Rgs14 in adipocytes, which leads to enhanced beta-adrenergic receptor signaling. Conversely, genetic deletion of Gpr35 causes progressive weight gain and glucose intolerance, and sensitizes to the effects of high-fat diets. Finally, exercise-induced adipose tissue browning is compromised in Gpr35 knockout animals. This work uncovers kynurenine metabolism as a pathway with therapeutic potential to control energy homeostasis.
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Tejido Adiposo/metabolismo , Tejido Adiposo/patología , Metabolismo Energético , Homeostasis , Inflamación/metabolismo , Inflamación/patología , Ácido Quinurénico/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Adipocitos/metabolismo , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Blanco/metabolismo , Adiposidad , Animales , Peso Corporal/efectos de los fármacos , Células Cultivadas , Dieta Alta en Grasa , Epidídimo/metabolismo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Glucosa/metabolismo , Linfocitos/metabolismo , Masculino , Ratones Endogámicos C57BL , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Condicionamiento Físico Animal , Proteínas RGS/metabolismo , Receptores Adrenérgicos beta/metabolismo , Receptores Acoplados a Proteínas G/deficiencia , Grasa Subcutánea/metabolismo , Transcripción GenéticaRESUMEN
AIMS: The current study tested the hypotheses that 1) an acute bout of aerobic exercise impairs isolated skeletal muscle contractile properties and 2) N-acetylcysteine (a thiol antioxidant; NAC) administration can restore the impaired muscle contractility after exercise. MAIN METHODS: At rest or immediately after an acute bout of aerobic exercise, extensor digitorum longus (EDL) and soleus muscles from male Wistar rats were harvested for ex vivo skeletal muscle contraction experiments. Muscles from exercised animals were incubated in Krebs Ringer's buffer in absence or presence of 20mM of NAC. Force capacity and fatigue properties were evaluated. KEY FINDINGS: Exercised EDL and soleus displayed lower force production across various stimulation frequencies (p<0.001), indicating that skeletal muscle force production was impaired after an acute bout of exercise. However, NAC treatment restored the loss of force production in both EDL and soleus after fatiguing exercise (p<0.05). Additionally, NAC treatment increased relative force production at different time points during a fatigue-induced protocol, suggesting that NAC treatment mitigates fatigue induced by successive contractions. SIGNIFICANCE: NAC treatment improves force capacity and fatigue properties in ex vivo skeletal muscle from rats submitted to an acute bout of aerobic exercise.