Muscle Tissue Of Mice Research Articles

Multi-omics study on the effect of moderate-intensity exercise on protein lactylation in mouse muscle tissue

IntroductionThis study explores the effects of moderate-intensity exercise on protein lactylation in mouse muscle tissue metabolism.MethodsHealthy adult mice running for 6 weeks as an exercise model and sedentary mice as the control were used to perform transcriptomic, proteomic, lactylation-proteomic, and metabolomic analyses. Correlation analysis between transcriptome and proteome and between proteome and metabolome was also conducted.ResultsIn this study, 159 lactylation sites of 78 proteins were identified as being differentially regulated by moderate-intensity exercise. Enrichment analysis showed that the lactylation of proteins Atp5mg, and Atp5po exhibited ATP hydrolysis activity. Mtatp8 and Atp5po were involved in biological processes such as mitochondrial transmembrane transport, and Mtatp8, Atp5mg, and Atp5po participate in oxidative phosphorylation and thermogenesis pathways. The lactylation levels of Mtatp8, Atp5mg, and Atp5po proteins in the exercise group were significantly decreased, while their protein levels were significantly increased. The combined analysis of proteomics and metabolomics showed that the oxocarboxylic acid metabolism and sphingolipid signaling pathways had significant changes under the influence of moderate-intensity exercise.DiscussionOur results indicate that moderate-intensity exercise has an effect on the lactylation level of mice, possibly by reducing the lactylation levels of Mtatp8, Atp5mg, and Atp5po and increasing the expression of their protein levels, thereby regulating the oxidative phosphorylation pathway and participating in energy metabolism. Further exploration is needed into the 2-oxocarboxylic acid metabolism pathway and the sphingolipid signaling pathway.

Folliculin Interacting Protein 1 (FNIP-1) expression and capillary density in gastrocnemius muscle tissue of mice after biological maturation period

Introduction: The biological maturity period is the time or tempo of progress toward adulthood or maturity. The hormonal fluctuations play an important role in changing the characteristics of human body tissues during the biological maturity period. However, changes in tissue characteristics during biological maturity period have not been revealed. Skeletal muscle tissue is one of those believed to experience changes. Muscle fibers are thought to experience switching types from type 2 muscle fibers to type 1 muscle fibers. The transition of muscle fibers from type 2 to type 1 requires miR-499 activity from the expression of the Myh7b gene. MiR-499 directly inhibits FNIP-1. However, the biological maturity period of changing FNIP-1 expression has not been confirmed. Objective: This study aimed to analyse the effect of the biological maturity period on FNIP-1 expression and capillary density in the gastrocnemius muscle. Methodology: Thirty-six male mice were divided into mature groups aged eight weeks and immature groups aged four weeks. This study analyzed FNIP-1 and capillary density gastrocnemius muscle of mice using immunohistochemistry. Results: FNIP-1 expression test showed higher in immature mice than mature mice. In comparison, the capillary density test and endurance showed higher expression in mature mice than in immature mice. Conclusion: This study concludes maturation was characterized by a low distribution of FNIP-1 expression in the gastrocnemius muscle and a longer duration ability to run on the treadmill. Unfortunately the capillary density was not a specific mark to determine maturation in mice.

Effects of forced treadmill exercise on lipid and carbohydrate metabolism parameters in a mouse model of type 2 diabetes mellitus

Aim. To study the effect of forced treadmill exercise on lipid and carbohydrate metabolism parameters in liver and skeletal muscle tissues of mice with a model of type 2 diabetes mellitus, taking into account age and biological rhythm characteristics.Materials and methods. To create a model of type 2 diabetes mellitus (T2DM), a high-fat diet was used. Physical activity in the form of forced treadmill exercise was carried out for 4 weeks. Parameters of lipid and carbohydrate metabolism in muscle and liver tissues were determined by Western blotting.Results. A decrease in glycogen content in the muscles in T2DM was associated with activation of its breakdown rather than with its reduced synthesis. Significant and multidirectional changes were recorded in the content of glycogen phosphorylase in the liver and skeletal muscle tissues. These changes were significantly influenced by both the nature of diet and physical activity. The development of T2DM in mice was accompanied by a decrease in high-density lipoprotein (HDL) content in the liver along with an increase in low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) levels. It is worth noting that physical activity provided partial normalization of the ratio of lipid fractions, despite the fact that the exercises were performed in the context of a high-fat diet. In the T2DM group, metabolic changes caused by both T2DM modeling and physical exercises were not only quantitative, but in some cases also qualitative. The effects of physical exercises performed at different times of the day on metabolic processes in the liver and muscle tissues varied significantly.Conclusion. Physical activity can help prevent not only metabolic disorders (obesity and insulin resistance), but also associated complications on the part of the liver and cardiovascular system.

Human PBMC-based humanized mice exhibit myositis features and serve as a drug evaluation model

Idiopathic inflammatory myopathies (IIMs) are a group of autoimmune disorders characterized by immune cell infiltration of muscle tissue accompanied by inflammation. Treatment of IIMs is challenging, with few effective therapeutic options due to the lack of appropriate models that successfully recapitulate the features of IIMs observed in humans. In the present study, we demonstrate that immunodeficient mice transplanted with human peripheral blood mononuclear cells (hPBMCs) exhibit the key pathologic features of myositis observed in humans and develop graft-versus-host disease. The hPBMC mice exhibit elevated serum levels of creatine kinase and aspartate transaminase, markers of myositis, and increased expression levels of myositis-related genes, such as vascular cell adhesion molecule 1, intercellular adhesion molecule 1, and serum amyloid A1, in muscle tissues. Histopathologic and flow cytometric analyses reveal the infiltration of CD8+ T cells in the muscle tissue of hPBMC mice, similar to that observed in patients with myositis, particularly in those with polymyositis. Transplantation of CD8+ T cell-depleted hPBMC leads to a significant reduction in polymyositis-like symptoms, in agreement with previous studies demonstrating CD8+ T cells as the main pathologic drivers of polymyositis. Furthermore, the transcriptome analysis of muscle tissue from hPBMC mice reveal extensive upregulation of characteristic genes of polymyositis, providing further support that hPBMC mice accurately reflect the pathophysiology of myositis in humans. Finally, administration of prednisolone or tacrolimus, which are commonly used for IIM treatment, leads to significant alleviation of myositis findings. Therefore, we propose that hPBMC mice should be considered as a model that accurately reflects the pathophysiology of myositis in human patients.

Plumbagin alleviates muscle atrophy in female mice through inhibiting the DANCR/NF-κB axis

BackgroundMuscle atrophy is a condition of the skeletal muscular system closely related to inflammation and significantly affects a person's quality of life and physical activity. It is characterized primarily by the progressive loss of muscle mass, strength, and function. Plumbagin (PB), the main bioactive component of the traditional Chinese medicine Plumbago zeylanica L., has bFeen shown to treat various inflammatory diseases, such as osteoporosis, osteoarthritis, and sepsis. Furthermore, many biological processes, including inflammation, involve differentiation antagonistic nonprotein-coding RNA (DANCR). However, their role and clinical importance in myogenesis and amyotrophy are not well understood. PurposeThis study aimed to explore the role of DANCR and the inflammatory response in the anti-muscle atrophy effects of PB. MethodsThe expression of DANCR in muscle atrophic mice and during myogenic differentiation was examined using quantitative reverse transcription PCR (RT‒qPCR). The mechanism of DANCR in muscle atrophy was confirmed through gene knockdown, RNA sequencing (RNA-seq), RNA pull-down, RNA immunoprecipitation (RIP), immunofluorescence (IF), and luciferase reporter gene assays. Bioinformatics was utilized to investigate the mechanism by which PB treatment affects muscle atrophy. The relationship between PB and DANCR was verified by surface plasmon resonance (SPR) and RT‒qPCR. Additionally, the role of PB in muscle atrophy was explored through its control of DANCR-mediated regulation of the NF-κB pathway. Finally, the effect of PB on the myogenic differentiation of human skeletal muscle cells (HsKMCs) was investigated. ResultsDANCR expression was upregulated in the muscle tissues of mice with muscle atrophy and downregulated during myogenic differentiation. Knockout of DANCR promoted myogenic differentiation and significantly alleviated the loss of muscle mass, strength, and function in mice with muscle atrophy. The primary mechanism involved DANCR directly binding to the p65 protein to regulate NF-κB pathway activity. Experiments revealed that PB could target the degradation of DANCR, reduce the nuclear entry of p65, and inhibit the activation of the NF-κB pathway. Consequently, PB significantly inhibited myotube atrophy and the inflammatory response in HsKMCs and promoted their myogenic differentiation by regulating the NF-κB pathway. ConclusionsOur results suggest that PB regulates myogenesis and prevents amyotrophy by targeting the degradation of DANCR and inhibiting the activation of the NF-κB pathway. This study reveals the crucial role of DANCR in maintaining muscle physiology during muscle atrophy and identifies PB as an effective drug that can target DANCR degradation to alleviate muscle atrophy.

Safe and Orally Bioavailable Inhibitor of Serine Palmitoyltransferase Improves Age-Related Sarcopenia.

The accumulation of ceramides and related metabolites has emerged as a pivotal mechanism contributing to the onset of age-related diseases. However, small molecule inhibitors targeting the ceramide de novo synthesis pathway for clinical use are currently unavailable. We synthesized a safe and orally bioavailable inhibitor, termed ALT-007, targeting the rate-limiting enzyme of ceramide de novo synthesis, serine palmitoyltransferase (SPT). In a mouse model of age-related sarcopenia, ALT-007, administered through the diet, effectively restored muscle mass and function compromised by aging. Mechanistic studies revealed that ALT-007 enhances protein homeostasis in Caenorhabditis elegans and mouse models of aging and age-related diseases, such as sarcopenia and inclusion body myositis (IBM); this effect is mediated by a specific reduction in very-long chain 1-deoxy-sphingolipid species, which accumulate in both muscle and brain tissues of aged mice and in muscle cells from IBM patients. These findings unveil a promising therapeutic avenue for developing safe ceramide inhibitors to address age-related neuromuscular diseases.

Investigation of rs1746661 Polymorphism in FNDC5 Gene in Obese Patients

Background: Obesity is a multifactorial disorder that has considerably increased in developing countries in recent years. This disease results from an imbalance between energy intake and expenditure, influenced by various factors such as behavior, diet, environment, metabolic factors, and genetics. Different genetic aspects of obesity seek mutations in genes that are responsible for appetite control and metabolism. FNDC5 is a glycosylated membrane protein that is highly expressed in the heart, brain, and skeletal muscle tissues in mice. This protein is cleaved by an unknown protease at the cell surface. This study aimed to investigate the rs1746661 polymorphism in the FNDC5 gene among obese patients. Materials and Methods: The blood samples were collected from 100 individuals visiting Shariati Hospital in Isfahan and the Social Security Clinic for DNA extraction using the phenol-chloroform method, and informed consent was obtained from them for their participation in the study. Specific primers for G/A/T alleles were designed for the amplification refractory mutation system-polymerase chain reaction (PCR) method, and PCR was performed. The results were examined on agarose gel electrophoresis and statistically analyzed using SPSS 22 software. Results: Based on genetic analysis investigations, our findings revealed a significant association between the GT genotype in the rs1746661 polymorphism and the occurrence of obesity and/or other metabolic disorders. Such genotypes can be considered predisposing polymorphisms for obesity and/or other metabolic problems. Conclusion: Overall, the multifactorial nature of obesity, such as lifestyle and dietary habits, should receive special attention.

Therapeutic effect and mechanism of Jingfang Granules on chronic fatigue syndrome based on intestinal flora and metabolomics

This study aims to investigate the protective effect and potential mechanism of Jingfang Granules(JF) on the mouse model of chronic fatigue syndrome(CFS). Mice were randomized into normal, model, and low-, medium-, and high-dose(0.9, 1.8, and 3.6 g·kg~(-1)·d~(-1), respectively) JF groups according to the body weight. In addition to the normal group, other groups of mice received exhaustive swimming training and tail suspension training every day for the modeling of CFS. The mice in each administration group were administrated with JF at the corresponding dose by gavage, and those in the other groups were administrated with an equal amount of purified water. The exhaustive swimming and tail suspension tests were conducted in each group. The UV-glutamate dehydrogenase method was used to determine the serum level of urea nitrogen(UREA), and the lactate dehydrogenase(LDH) assay kit was used to determine the LDH level. Enzyme-linked immunosorbent assay was employed to measure the levels of interleukin-6(IL-6) and tumor necrosis factor-α(TNF-α) in the serum, muscle tissue, and brain tissue of mice in each group. Western blot was employed to determine the expression levels of Toll-like receptor 4(TLR4), myeloid differentiation factor 88(MyD88), nuclear factor-kappa B(NF-κB) and their phosphorylated proteins in the muscle tissue of mice. The 16S rDNA sequencing and ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) were adopted to detect the changes of intestinal flora and intestinal metabolites in mice. Compared with the model group, JF significantly prolonged the swimming exhaustion time and shortened the tail suspension time of the model mice, lowered the levels of LDH and UREA in the serum as well as the levels of IL-6 and TNF-α in the serum, muscle tissue, and brain tissue of CFS mice. In addition, JF down-regulated the expression of TLR4, MyD88, and p-NF-κB/NF-κB in the muscle tissue of CFS mice compared with the model group. The results of 16S rDNA sequencing demonstrated that JF ameliorated the intestinal flora disorder of CFS mice. The results of UPLC-MS/MS revealed that JF significantly affected the histidine metabolism pathway in the intestinal tract of CFS mice. Spearman analysis displayed that histamine, a metabolite involved in histidine metabolism, was negatively correlated with the abundance of Clostridia＿UCG-014, Dubosiella, and RF39 and positively correlated with the abundance of Coriobacteriaceae＿UCG-002. The metabolite imidazole-4-acetaldehyde was negatively correlated with the abundance of Clostridia＿UCG-014, Dubosiella, and RF39 and positively correlated with the abundance of Coriobacteriaceae＿UCG-002. In conclusion, JF can increase the swimming exhaustion time, reduce the immobility time of tail suspension, lower serum LDH and UREA levels, and alleviate inflammation response. It may exert the therapeutic effect by improving intestinal flora homeostasis and inhibiting histidine metabolism by down-regulating the expression of proteins in the TLR4/MyD88/NF-κB signaling pathway, thereby relieving the symptoms of CFS in mice.

GlutaR: A High‐Performance Fluorescent Protein‐Based Sensor for Spatiotemporal Monitoring of Glutamine Dynamics In Vivo

AbstractGlutamine is the most abundant amino acid in human blood and muscle, and is integral to a wide variety of functions in cancer cells. However, the inability to monitor the subcellular distribution of glutamine in real‐time has obscured understanding of glutamine metabolism under physiological and pathological conditions. Here, we report the development of a genetically encoded fluorescent sensor and demonstrate how this GlnBP‐cpYFP fusion “GlutaR sensor” undergoes glutamine‐induced conformational changes reflected in detectable fluorescence responses. Obtained after iterative screening of approximately 1,600 variants, GlutaR exhibits a ratiometric readout, fast response kinetics, and high responsivity (R488/405 of ~1000 %), and we demonstrate its selectivity for monitoring glutamine fluctuations in multiple cell types. Additionally, using digitonin permeabilization of GlutaR HeLa cells, we generated a calibration curve and performed in situ titration to quantify free glutamine concentrations in subcellular compartments (cytosol, nucleus, mitochondria). Subsequently, we applied GlutaR to investigate how chemical and genetic inhibition of glutamine synthetase (GS) and glutaminase (GLS) differentially alter glutamine levels in subcellular compartments. Finally, we demonstrate GlutaR's ability to monitor dynamic glutamine levels in muscle and liver tissues of diabetic mice in vivo. These findings collectively demonstrate GlutaR as a versatile tool for the spatiotemporal characterization of glutamine metabolism in living cells and tissues.

Detection of miR-133a-5p Using a Molecular Beacon Probe for Investigating Postmortem Intervals.

Background: When a body is discovered at a crime or murder scene, it is crucial to examine the body and estimate its postmortem interval (PMI). Accurate estimation of PMI is vital for identifying suspects and providing clues to resolve the case. MicroRNAs (miRNAs or miRs) are small non-coding RNAs that remain relatively stable in the cell nucleus even after death-related changes occur. Objective: This study developed a molecular beacon probe for mmu-miR-133a-5p and assessed its use in mouse muscle tissue at temperatures of 4 °C and 21 °C to estimate the PMI. Methods: A total of 36 healthy adult male BALB/c mice were divided into 9 PMI time points (0, 2, 6, 8, and 10 days) with 3 mice per time point, and they were exposed to 4 °C and 21 °C. Next, the expression pattern of mmu-miR-133a in the skeletal muscle tissue over a 10-day PMI period was analyzed using the developed molecular beacon probe. Results: The molecular beacon (MB) probe was designed for optimal thermodynamic stability with a hairpin structure that opened in the presence of mmu-miR-133a-5p, thus separating the fluorophore from the quencher and resulting in a strong fluorescence signal at 495 nm. Fluorescence intensity increased with mmu-miR-133a-5p concentration from 1 ng/μL to 1000 ng/μL and exhibited a strong correlation (R2 = 0.9966) and a detection limit of 1 ng/μL. Subsequently, the expression level of mmu-miR-133a-5p was observed to be stable in mouse skeletal muscle tissue at both 4 °C and 21 °C. Conclusions: This user-friendly assay can complete measurements in just 30 min after RNA extraction and is suitable for point-of-care testing, and it possesses the potential to improve existing complex and time-consuming methods for PMI estimation.

DNA Aptamer-based Sensitive Electrochemical Biosensor for NAD(H) Detection

Nicotinamide-adenine dinucleotide (NAD(H)) plays a critical role in cellular metabolism, and its accurate measurement is essential for elucidating biological mechanisms and disease progression. However, specific recognition probes and sensitive biosensors for NAD(H) remains a significant challenge. Here, we screen an aptamer (NAD3-1a) that exhibits specific binding to NAD(H) with micromolar affinity. By incorporating this aptamer with tetrahedral DNA nanostructure, we develop a highly selective and sensitive electrochemical biosensor for the detection of NAD(H). This biosensor enables precise detection of NAD(H) within a linear range of 10-12∼10-7 M, offering remarkable stability and reproducibility. Utilizing this biosensor, we observed significant variations in the NAD(H) levels between normal and tumor cells, as well as a notable reduction in NAD(H) in the skeletal muscle tissues of aged mice. These results highlight the potential of this aptamer-based biosensor to advance our understanding of metabolic variations in both health and disease contexts.

GlutaR: A High-Performance Fluorescent Protein-Based Sensor for Spatiotemporal Monitoring of Glutamine Dynamics In Vivo.

Glutamine is the most abundant amino acid in human blood and muscle, and is integral to a wide variety of functions in cancer cells. However, the inability to monitor the subcellular distribution of glutamine in real-time has obscured understanding of glutamine metabolism under physiological and pathological conditions. Here, we report the development of a genetically encoded fluorescent sensor and demonstrate how this GlnBP-cpYFP fusion "GlutaR sensor" undergoes glutamine-induced conformational changes reflected in detectable fluorescence responses. Obtained after iterative screening of approximately 1,600 variants, GlutaR exhibits a ratiometric readout, fast response kinetics, and high responsivity (R488/405 of ~1000 %), and we demonstrate its selectivity for monitoring glutamine fluctuations in multiple cell types. Additionally, using digitonin permeabilization of GlutaR HeLa cells, we generated a calibration curve and performed in situ titration to quantify free glutamine concentrations in subcellular compartments (cytosol, nucleus, mitochondria). Subsequently, we applied GlutaR to investigate how chemical and genetic inhibition of glutamine synthetase (GS) and glutaminase (GLS) differentially alter glutamine levels in subcellular compartments. Finally, we demonstrate GlutaR's ability to monitor dynamic glutamine levels in muscle and liver tissues of diabetic mice in vivo. These findings collectively demonstrate GlutaR as a versatile tool for the spatiotemporal characterization of glutamine metabolism in living cells and tissues.

Resistance Training and Resveratrol Supplementation Improve Cancer Cachexia and Tumor Volume in Muscle Tissue of Male Mice Bearing Colon Cancer CT26 Cell Tumors.

Losing muscle functions due to reducing muscle mass and quality is one of the main features of cancer cachexia that impairs patients' quality of life and decrease their survival. This study aimed to investigate the synergistic effects of resistance training and resveratrol supplementation on cachexia induced by CT26 tumors in male mice. Forty-eight mice were divided into eight groups randomly: healthy sedentary vehicle (HSV), healthy exercise vehicle (HEV), healthy sedentary resveratrol (HSR), healthy exercise resveratrol (HER), CT-26 tumor-bearing sedentary vehicle (TSV), CT-26 tumor-bearing exercise vehicle (TEV), CT-26 tumor-bearing sedentary resveratrol (TSR) and CT-26 tumor-bearing exercise resveratrol (TER). Training groups performed ladder climbing with weights tied to their tails, for six weeks. Resveratrol-treated groups received 50 mg/kg daily by gavage. The results showed muscle weight, and mTORC1 phosphorylation decreased in TSV compared to the HSV group. mTORC1 phosphorylation was increased in TER compared to TSV, TEV, and TSR. In addition, AMPK phosphorylation was more elevated in HER compared to HSV, HEV, and HSR. LC3BII/I ratio was higher in TSV than HSV group. Tumor volume was increased in all groups, with the lowest increase in TER group. In tumor tissue, mTORC1 phosphorylation was decreased in TER than in TSV, TEV, and TSR groups; AMPK phosphorylation and LC3BII/I ratio were increased in TSV than in TEV, TSR, and TER groups. In conclusion, the synergistic effect of resistance training and resveratrol supplementation is the most effective in reducing tumor volume. These advantages were mostly in line with molecular findings.

Long-Term Administration of Nicotinamide Mononucleotide Mitigates High-Fat-Diet-Induced Physiological Decline in Aging Mice

BackgroundNicotinamide adenine dinucleotide (NAD+) levels decline with age, and boosting it can improve multi-organ functions and lifespan. ObjectivesNicotinamide mononucleotide (NMN) is a natural NAD+ precursor with the ability to enhance NAD+ biosynthesis. Numerous studies have shown that a high-fat diet (HFD) can accelerate the process of aging and many diseases. We hypothesized that long-term administration of NMN could exert protective effects on adipose, muscle, and kidney tissues in mice on an HFD act by affecting the autophagic pathway. MethodsMice at 14 mo of age were fed an HFD, and NMN was added to their drinking water at a dose of 400 mg/kg for 7 mo. The locomotor ability of the mice was assessed by behavioral experiments such as grip test, wire hang test, rotarod, and beam-walking test. At the end of the behavioral experiments, the pathological changes of each peripheral organ and the expression of autophagy-related proteins, as well as the markers of the senescence and inflammaging were analyzed by pathological staining, immunohistochemical staining, and western blotting, respectively. ResultsWe found that NMN supplementation increased NAD+ levels and ultimately attenuated age- and diet-related physiological decline in mice. NMN inhibited HFD-induced obesity, promoted physical activity, improved glucose and lipid metabolism, improved skeletal muscle function and renal damage, as well as mitigated the senescence and inflammaging as demonstrated by p16, interleukin 1β, and tumor necrosis factor α levels. In addition, the present study further emphasizes the potential mechanisms underlying the bidirectional relationship between NAD+ and autophagy. We detected changes in autophagy levels in various tissue organs, and NMN may play a protective role by inhibiting excessive autophagy induced by HFD. ConclusionsOur findings demonstrated that NMN administration attenuated HFD-induced metabolic disorders and physiological decline in aging mice.

Inhibition of MAT2A Impairs Skeletal Muscle Repair Function.

The regenerative capacity of muscle, which primarily relies on anabolic processes, diminishes with age, thereby reducing the effectiveness of therapeutic interventions aimed at treating age-related muscle atrophy. In this study, we observed a decline in the expression of methionine adenosine transferase 2A (MAT2A), which synthesizes S-adenosylmethionine (SAM), in the muscle tissues of both aged humans and mice. Considering MAT2A's critical role in anabolism, we hypothesized that its reduced expression contributes to the impaired regenerative capacity of aging skeletal muscle. Mimicking this age-related reduction in the MAT2A level, either by reducing gene expression or inhibiting enzymatic activity, led to inhibiting their differentiation into myotubes. In vivo, inhibiting MAT2A activity aggravated BaCl2-induced skeletal muscle damage and decreased the number of satellite cells, whereas supplementation with SAM improved these effects. RNA-sequencing analysis further revealed that the Fas cell surface death receptor (Fas) gene was upregulated in Mat2a-knockdown C2C12 cells. Suppressing MAT2A expression or activity elevated Fas protein levels and increased the proportion of apoptotic cells. Additionally, inhibition of MAT2A expression or activity increased p53 expression. In conclusion, our findings demonstrated that impaired MAT2A expression or activity compromised the regeneration and repair capabilities of skeletal muscle, partially through p53-Fas-mediated apoptosis.

The molecular signature of the peripheral cannabinoid receptor 1 antagonist AM6545 in adipose, liver and muscle tissue

The endocannabinoid system plays an important role in the regulation of metabolism, growth and regeneration of peripheral tissues, including liver, adipose and muscle tissue. Studies in cells, rodents and humans showed that cannabinoid receptor 1 (CB1) antagonist treatment is an effective strategy to improve features of metabolic health such as substrate metabolism, at least in models of metabolic dysregulation. However, acute signaling events that might induce these metabolic adaptations are not understood. It is not clear whether, and to which extent, a single treatment with a CB1 antagonist induces acute effects in peripheral, metabolic tissues. Therefore, the present study compared the phosphorylation status of signaling pathways and metabolic markers in liver, adipose and muscle tissue of mice treated with the peripherally restricted CB1 antagonist AM6545 and vehicle-treated mice. Protein kinase A phosphorylation was downregulated in white and brown adipose tissue, whereas the mitogen-activated protein kinase, phospho-extracellular signal-regulated kinase, was higher in liver, white adipose and muscle tissue of AM6545-treated mice. Additionally, Akt-mammalian target of rapamycin activation was higher in all tissues of AM6545-treated mice, whereas the phosphorylation status of metabolic markers remained unaffected. These data indicate that acute CB1 antagonism is effective to induce phosphorylation events of signaling cascades and metabolic markers in metabolic tissues of healthy, lean mice within a 90-min time window. The observed adaptations to AM6545 treatment do not fully align with earlier in vitro and in vivo findings, which could be ascribed to differences in cell type, exposure intensity (dose and time), health status and species.

New Glycotoxin Inhibitor from Sesuvium sesuvioides Mitigates Symptoms of Insulin Resistance and Diabetes by Suppressing AGE-RAGE Axis in Skeletal Muscle.

The current study intended to investigate the role of new natural compounds derived from the Sesuvium sesuvioides plant in mitigating symptoms of diabetes and insulin resistance in the diabetic mice model. Anti-advanced glycation activity, insulin, and adiponectin were quantified by enzyme-linked immunosorbent assay (ELISA). Glucose uptake was performed using enzymatic fluorescence assay, and glycogen synthesis was measured using PAS staining. Gene and protein expression was assessed using real time PCR (RT-PCR), and immunoblotting and fluorescent microscopy, respectively. The new flavonoid glycoside eupalitin 3-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside 1 isolated from S. sesuvioides exhibited anti-AGE activity by reducing human glycated albumin in liver cells. In a diabetic mouse model treated with compound 1, we observed improved glucose tolerance, increased adiponectin levels, and decreased insulin resistance. We also observed alleviated AGEs induced reduction in glucose uptake and restored glycogen synthesis in the compound 1-treated diabetic mice muscles. Exploring the molecular mechanism of action in skeletal muscle tissue of diabetic mice, we found that 1 reduced AGE-induced reactive oxygen species and the inflammatory gene in the muscle of diabetic mice. Additionally, 1 exhibited these effects by reducing the gene and protein expression of receptor for advanced glycation end products (RAGE) and inhibiting protein kinase C (PKC) delta activation. This further led us to demonstrate that compound 1 reduced serine phosphorylation of IRS-1, thereby restoring insulin sensitivity. We conclude that a new flavonoid glycoside from S. sesuvioides could be a therapeutic target for the treatment of symptoms of insulin resistance and diabetes.

Gingipain from Porphyromonas gingivalis causes insulin resistance by degrading insulin receptors through direct proteolytic effects

Periodontitis is a critical risk factor for the occurrence and development of diabetes. Porphyromonas gingivalis may participate in insulin resistance (IR) caused by periodontal inflammation, but the functional role and specific mechanisms of P. gingivalis in IR remain unclear. In the present study, clinical samples were analysed to determine the statistical correlation between P. gingivalis and IR occurrence. Through culturing of hepatocytes, myocytes, and adipocytes, and feeding mice P. gingivalis orally, the functional correlation between P. gingivalis and IR occurrence was further studied both in vitro and in vivo. Clinical data suggested that the amount of P. gingivalis isolated was correlated with the Homeostatic Model Assessment for IR score. In vitro studies suggested that coculture with P. gingivalis decreased glucose uptake and insulin receptor (INSR) protein expression in hepatocytes, myocytes, and adipocytes. Mice fed P. gingivalis tended to undergo IR. P. gingivalis was detectable in the liver, skeletal muscle, and adipose tissue of experimental mice. The distribution sites of gingipain coincided with the downregulation of INSR. Gingipain proteolysed the functional insulin-binding region of INSR. Coculture with P. gingivalis significantly decreased the INSR–insulin binding ability. Knocking out gingipain from P. gingivalis alleviated the negative effects of P. gingivalis on IR in vivo. Taken together, these findings indicate that distantly migrated P. gingivalis may directly proteolytically degrade INSR through gingipain, thereby leading to IR. The results provide a new strategy for preventing diabetes by targeting periodontal pathogens and provide new ideas for exploring novel mechanisms by which periodontal inflammation affects the systemic metabolic state.

Diet Based on Pereskia aculeata Miller Flour Increases Muscle Volume and Modulates the Expression of Myokines in Mice Subjected to Resistance Training.

The study aimed to evaluate the effects of Pereskia aculeata Miller (ora-pro-nobis [OPN]) flour on body and biochemical parameters, thermogenic activity, and molecular expression of markers in the muscle tissue of mice subjected to resistance training (RT). Twelve mice were randomly assigned to two groups (n=6 animals/group): G1: control (Control) fed a standard diet + RT and G2: experimental (OPN) fed a diet based on OPN flour + RT. The RT consisted of a 6-week program using a vertical ladder combined with a fixed weight attached to the animal. Several parameters were measured, including assessment of body composition, biochemical markers, thermogenic activity, and molecular (mRNA expression of interleukin (IL)-6, fibronectin type III domain-containing protein 5 (FNDC5), peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), nuclear respiratory factor 1 (NRF1), and mitochondrial transcription factor A (TFAM). The OPN group exhibited a decrease in body weight and visceral adiposity, higher energy expenditure, and lipid oxidation rate. In addition, it was observed an increase in muscle volume and in mRNA expression levels of IL-6, FNDC5, PGC-1α, and TFAM. These findings suggest that OPN flour could be a nutritional option to enhance performance in RT.

Curcumin-activated Wnt5a pathway mediates Ca2+ channel opening to affect myoblast differentiation and skeletal muscle regeneration.

Skeletal muscle injury is one of the most common sports injuries; if not properly treated or not effective rehabilitation treatment after injury, it can be transformed into chronic cumulative injury. Curcumin, an herbal ingredient, has been found to promote skeletal muscle injury repair and regeneration. The Wnt5a pathway is related to the expression of myogenic regulatory factors, and Ca2+ promotes the differentiation and fusion process of myoblasts. This study explored the effect and mechanism of curcumin on myoblast differentiation during the repair and regeneration of injured skeletal muscle and its relationship with the Wnt5a pathway and Ca2+ channel. Myogenic differentiation of C2C12 cells was induced with 2% horse serum, and a mouse (male, 10weeks old) model of acute skeletal muscle injury was established using cardiotoxin (20μL). In addition, we constructed a Wnt5a knockdown C2C12 cell model and a Wnt5a knockout mouse model. Besides, curcumin was added to the cell culture solution (80mg/L) and fed to the mice (50mg/kg). Fluorescence microscopy was used to determine the concentration of Ca2+. Western blot and RT-qPCR were used to detect the protein and mRNA levels of Wnt5a, CaN, NFAT2, MyoD, Myf5, Pax7, and Myogenin. The expression levels of MyoD, Myf5, Myogenin, MHC, Desmin, and NFAT2 were detected using immunofluorescence techniques. In addition, MyoD expression was observed using immunohistochemistry, and morphological changes in mouse muscle tissue were observed using HE staining. During myoblast differentiation and muscle regeneration, Wnt5a expression was upregulated (P<0.001) and the Wnt5a signalling pathway was activated. Wnt5a overexpression promoted the expression of MyoD, Myf5, Myogenin, MHC, and Desmin (P<0.05), and conversely, knockdown of Wnt5a inhibited their expression (P<0.001). The Wnt5a pathway mediated the opening of Ca2+ channels, regulated the expression levels of CaN, NFAT2, MyoD, Myf5, Myogenin, MHC, and Desmin (P<0.01) and promoted the differentiation of C2C12 myoblasts and the repair and regeneration of injured skeletal muscle. The expression of Wnt5a, CaN, NFAT2, MyoD, Myogenin, Myf5, and MHC in C2C12 myoblast was significantly increased after curcumin intervention (P<0.05); however, their expression decreased significantly after knocking down Wnt5a on the basis of curcumin intervention (P<0.05). Similarly, in Wnt5a knockout mice, the promotion of muscle regeneration by curcumin was significantly attenuated. Curcumin can activate the Wnt5a signalling pathway and mediate the opening of Ca2+ channels to accelerate the myogenic differentiation of C2C12 cells and the repair and regeneration of injured skeletal muscle.