Regulation Of Muscle Metabolism Research Articles

Dietary Pleurotus citrinopileatus Polysaccharide Improves Growth Performance and Meat Quality Associated with Alterations of Gut Microbiota in Arbor Acre Broilers.

Adding edible fungal polysaccharides to animal diets improves growth performance, meat quality, intestinal health, and immunity without adverse effects. This study aimed to evaluate the impact of Pleurotus citrinopileatus polysaccharide (PCP, including PCP250, PCP500, PCP750, and PCP1000 mg/kg) on the growth performance, meat quality, and microbial composition of Arbor Acre (AA) broilers (total 180) by metabolomics and high-throughput sequencing. The results showed that adding PCP enhanced chicken meat tenderness, redness (a*), and water retention and raised essential amino acids and flavor amino acids (such as umami and sweet amino acids) content. The metabolomics revealed that IMP, creatine, betaine, sarcosine, and taurine were related to improving meat quality in broilers by PCP addition. In addition, amino acid, purine, and lipid metabolism were the main metabolic pathways. Moreover, PCP could regulate muscle metabolism by increasing the relative abundance of Lachnospiraceae and Lactobacillus and the content of short-chain fatty acids (SCFAs). Therefore, PCP may become a promising new dietary supplement in the future, which may improve the yield and quality of broiler chickens.

Effects of thyroid hormones in skeletal muscle protein turnover.

Thyroid hormones (THs) are critical regulators of muscle metabolism in both healthy and unhealthy conditions. Acting concurrently as powerful anabolic and catabolic factors, THs are endowed with a vital role in muscle mass maintenance. As a result, thyroid dysfunctions are the leading cause of a wide range of muscle pathologies, globally identified as myopathies. Whether muscle wasting is a common feature in patients with hyperthyroidism and is mainly caused by THs-dependent stimulation of muscle proteolysis, also muscle growth is often associated with hyperthyroid conditions, linked to THs-dependent stimulation of muscle protein synthesis. Noteworthy, also hypothyroid status negatively impacts on muscle physiology, causing muscle weakness and fatigue. Most of these symptoms are due to altered balance between muscle protein synthesis andbreakdown. Thus, a comprehensive understanding of THs-dependent skeletal muscle protein turnover might facilitate the management of physical discomfort or weakness in conditions of thyroid disease. Herein, we describe the molecular mechanisms underlying the THs-dependent alteration of skeletal muscle structure and function associated with muscle atrophy and hypertrophy, thus providing new insights for targeted modulation of skeletal muscle dynamics.

Genetic Deletion of Skeletal Muscle Inositol Polyphosphate Multikinase Disrupts Glucose Homeostasis and Impairs Exercise Tolerance.

Inositol phosphates are critical signaling messengers involved in a wide range of biological pathways in which inositol polyphosphate multikinase (IPMK) functions as a rate-limiting enzyme for inositol polyphosphate metabolism. IPMK has been implicated in cellular metabolism, but its function at the systemic level is still poorly understood. Since skeletal muscle is a major contributor to energy homeostasis, we have developed a mouse model in which skeletal muscle IPMK is specifically deleted and examined how a loss of IPMK affects whole-body metabolism. Here, we report that mice in which IPMK knockout is deleted, specifically in the skeletal muscle, displayed an increased body weight, disrupted glucose tolerance, and reduced exercise tolerance under the normal diet. Moreover, these changes were associated with an increased accumulation of triglyceride in skeletal muscle. Furthermore, we have confirmed that a loss of IPMK led to reduced beta-oxidation, increased triglyceride accumulation, and impaired insulin response in IPMK-deficient muscle cells. Thus, our results suggest that IPMK mediates the whole-body metabolism via regulating muscle metabolism and may be potentially targeted for the treatment of metabolic syndromes.

Neuronal innervation regulates the secretion of neurotrophic myokines and exosomes from skeletal muscle

Myokines and exosomes, originating from skeletal muscle, are shown to play a significant role in maintaining brain homeostasis. While exercise has been reported to promote muscle secretion, little is known about the effects of neuronal innervation and activity on the yield and molecular composition of biologically active molecules from muscle. As neuromuscular diseases and disabilities associated with denervation impact muscle metabolism, we hypothesize that neuronal innervation and firing may play a pivotal role in regulating secretion activities of skeletal muscles. We examined this hypothesis using an engineered neuromuscular tissue model consisting of skeletal muscles innervated by motor neurons. The innervated muscles displayed elevated expression of mRNAs encoding neurotrophic myokines, such as interleukin-6, brain-derived neurotrophic factor, and FDNC5, as well as the mRNA of peroxisome-proliferator-activated receptor γ coactivator 1α, a key regulator of muscle metabolism. Upon glutamate stimulation, the innervated muscles secreted higher levels of irisin and exosomes containing more diverse neurotrophic microRNAs than neuron-free muscles. Consequently, biological factors secreted by innervated muscles enhanced branching, axonal transport, and, ultimately, spontaneous network activities of primary hippocampal neurons in vitro. Overall, these results reveal the importance of neuronal innervation in modulating muscle-derived factors that promote neuronal function and suggest that the engineered neuromuscular tissue model holds significant promise as a platform for producing neurotrophic molecules.

Fibroblast Growth Factor 21: A Fascinating Perspective on the Regulation of Muscle Metabolism.

Fibroblast growth factor 21 (FGF21) plays a vital role in normal eukaryotic organism development and homeostatic metabolism under the influence of internal and external factors such as endogenous hormone changes and exogenous stimuli. Over the last few decades, comprehensive studies have revealed the key role of FGF21 in regulating many fundamental metabolic pathways, including the muscle stress response, insulin signaling transmission, and muscle development. By coordinating these metabolic pathways, FGF21 is thought to contribute to acclimating to a stressful environment and the subsequent recovery of cell and tissue homeostasis. With the emphasis on FGF21, we extensively reviewed the research findings on the production and regulation of FGF21 and its role in muscle metabolism. We also emphasize how the FGF21 metabolic networks mediate mitochondrial dysfunction, glycogen consumption, and myogenic development and investigate prospective directions for the functional exploitation of FGF21 and its downstream effectors, such as the mammalian target of rapamycin (mTOR).

An Artificial Intelligence Prediction Model of Insulin Sensitivity, Insulin Resistance, and Diabetes Using Genes Obtained through Differential Expression.

Insulin is a powerful pleiotropic hormone that affects processes such as cell growth, energy expenditure, and carbohydrate, lipid, and protein metabolism. The molecular mechanisms by which insulin regulates muscle metabolism and the underlying defects that cause insulin resistance have not been fully elucidated. This study aimed to perform a microarray data analysis to find differentially expressed genes. The analysis has been based on the data of a study deposited in Gene Expression Omnibus (GEO) with the identifier "GSE22309". The selected data contain samples from three types of patients after taking insulin treatment: patients with diabetes (DB), patients with insulin sensitivity (IS), and patients with insulin resistance (IR). Through an analysis of omics data, 20 genes were found to be differentially expressed (DEG) between the three possible comparisons obtained (DB vs. IS, DB vs. IR, and IS vs. IR); these data sets have been used to develop predictive models through machine learning (ML) techniques to classify patients with respect to the three categories mentioned previously. All the ML techniques present an accuracy superior to 80%, reaching almost 90% when unifying IR and DB categories.

Differential effects of Western diet and traumatic muscle injury on skeletal muscle metabolic regulation in male and female mice.

This study was designed to develop an understanding of the pathophysiology of traumatic muscle injury in the context of Western diet (WD; high fat and high sugar) and obesity. The objective was to interrogate the combination of WD and injury on skeletal muscle mass and contractile and metabolic function. Male and female C57BL/6J mice were randomized into four groups based on a two-factor study design: (1) injury (uninjured vs. volumetric muscle loss [VML]) and (2) diet (WD vs. normal chow [NC]). Electrophysiology was used to test muscle strength and metabolic function in cohorts of uninjured+NC, uninjured+WD, VML+NC and VML+WD at 8weeks of intervention. VML-injured male and female mice both exhibited decrements in muscle mass (-17%, P<0.001) and muscle strength (-28%, P<0.001); however, VML+WD females had a 28% greater muscle mass compared to VML+NC females (P=0.034), a compensatory response not detected in males. VML-injured male and female mice both had lower carbohydrate- and fat-supported muscle mitochondrial respiration (JO2 ) and less electron conductance through the electron transport system (ETS); however, male VML-WD had 48% lower carbohydrate-supported JO2 (P=0.014) and 47% less carbohydrate-supported electron conductance (P=0.026) compared to male VML+NC, and this diet-injury phenotype was not present in females. ETS electron conductance starts with complex I and complex II dehydrogenase enzymes at the inner mitochondrial membrane, and male VML+WD had 31% less complex I activity (P=0.004) and 43% less complex II activity (P=0.005) compared to male VML+NC. This was a diet-injury phenotype not present in females. Pyruvate dehydrogenase (PDH), β-hydroxyacyl-CoA dehydrogenase, citrate synthase, α-ketoglutarate dehydrogenase and malate dehydrogenase metabolic enzyme activities were evaluated as potential drivers of impaired JO2 in the context of diet and injury. There were notable male and female differential effects in the enzyme activity and post-translational regulation of PDH. PDH enzyme activity was 24% less in VML-injured males, independent of diet (P<0.001), but PDH enzyme activity was not influenced by injury in females. PDH enzyme activity is inhibited by phosphorylation at serine-293 by PDH kinase 4 (PDK4). In males, there was greater total PDH, phospho-PDHser293 and phospho-PDH-to-total PDH ratio in WD mice compared to NC, independent of injury (P≤0.041). In females, PDK4 was 51% greater in WD compared to NC, independent of injury (P=0.025), and was complemented by greater phospho-PDHser293 (P=0.001). Males are more susceptible to muscle metabolic dysfunction in the context of combined WD and traumatic injury compared to females, and this may be due to impaired metabolic enzyme functions.

1625-P: Osteoprotection by FNIP1 Signaling in Skeletal Muscle

Obesity is increasingly recognized to exert negative impact on bone mass. Skeletal muscle and bone are closely related throughout life, and muscle dysfunction can cause osteoporosis. Understanding of the crosstalk between muscle and bone could have implications for maintaining bone fitness in various disease states such as obesity. FNIP1 is emerging as key regulator of muscle metabolism acting via AMPK. However, the role of muscle FNIP1 in bone mass control is unknown. Using both gain- and loss-of function muscle-specific genetic models, we show that in addition to the known role in the regulation of mitochondrial function muscle fiber type, FNIP1 participates in muscle programs that govern bone homeostasis. FNIP1 KO mice showed a decrease in trabecular bone volume and bone mineral density, whereas muscle specific restoration of FNIP1 expression in KO mice (FNIP1Tg/KO) reversed the bone loss phenotypes. Femoral bending tests revealed a marked decrease in elastic modulus and maximum force in FNIP1 KO mice but increase in FNIP1 TgKO mice. Consistent with these findings, muscle cell-specific deletion of FNIP1 resulted in a pronounced bone structural and mechanical dysfunction. Using AMPKα1/α2 KO lines, we show that muscle FNIP1 exerts control actions upon bone homeostasis independently of AMPK. Through comprehensive RNA-seq and genomic analyses, we reveal that muscle FNIP1 deficiency induces IGF2 secretion, thereby driving an IGF2-depenent osteoclast program. Importantly, we also found that the muscle FNIP1-IGF2 regulatory circuit is associated with osteoporosis in humans. Thus, muscle FNIP1 is a critical safeguard of bone mass. These findings provide new therapeutic opportunities for enhancing muscle fitness to combat a variety of metabolic and musculoskeletal diseases. Disclosure M.Yan: None. Z.Xu: None. Y.Yin: None. T.Fu: None. Z.Zhou: None. L.Yang: None. Z.Gan: None.

Vemurafenib improves muscle histopathology in a mouse model of LAMA2-related congenital muscular dystrophy.

Laminin-α2-related congenital muscular dystrophy (LAMA2-CMD) is a neuromuscular disease affecting around 1-9 in 1,000,000 children. LAMA2-CMD is caused by mutations in the LAMA2 gene resulting in the loss of laminin-211/221 heterotrimers in skeletal muscle. LAMA2-CMD patients exhibit severe hypotonia and progressive muscle weakness. Currently, there is no effective treatment for LAMA2-CMD and patients die prematurely. The loss of laminin-α2 results in muscle degeneration, defective muscle repair and dysregulation of multiple signaling pathways. Signaling pathways that regulate muscle metabolism, survival and fibrosis have been shown to be dysregulated in LAMA2-CMD. As vemurafenib is a US Food and Drug Administration (FDA)-approved serine/threonine kinase inhibitor, we investigated whether vemurafenib could restore some of the serine/threonine kinase-related signaling pathways and prevent disease progression in the dyW-/- mouse model of LAMA2-CMD. Our results show that vemurafenib reduced muscle fibrosis, increased myofiber size and reduced the percentage of fibers with centrally located nuclei in dyW-/- mouse hindlimbs. These studies show that treatment with vemurafenib restored the TGF-β/SMAD3 and mTORC1/p70S6K signaling pathways in skeletal muscle. Together, our results indicate that vemurafenib partially improves histopathology but does not improve muscle function in a mouse model of LAMA2-CMD.

Sarcolipin ablation decreases whole body VO2 in young female nice

The sarco(endo)plasmic reticulum calcium (Ca 2+ ) ATPase (SERCA) pump is a major regulator of cytosolic Ca 2+ in striated muscle. Sarcolipin (SLN) reduces SERCA-mediated Ca 2+ pumping efficiency and is a key regulator of muscle metabolism and contractile function. With SERCA activity comprising approximately 12% of whole-body metabolic rate, the inefficient SERCA Ca 2+ cycling promoted by SLN would be predicted to increase metabolic rate. Although SLN is involved in adaptive diet-induced thermogenesis and overexpression of SLN increases metabolic rate and protects against diet-induced obesity, we found previously that SLN ablation had no effect on whole body metabolic rate or body composition in male mice that were fed a standard chow diet. However, unpublished work from our lab indicates that SLN expression in mouse soleus is significantly higher in females compared with males. Therefore, the purpose of this study was to investigate the effects of SLN ablation on body composition and metabolic rate of female mice. Adult (4-6mo) female wild type (WT) and SLN knockout (KO) mice (n=4 per group) were used to collect anthropometric measures (adiposity and body weight) and were housed in a comprehensive lab animal monitoring system (CLAMS) over a 48-hour period to assess daily whole body VO2 and total cage activity. With SLN ablation, total whole body VO 2 (ml/kg/hr) was lower (p&lt;0.05) in the KO females (3534 ± 95.1) compared to WT females (5080 ± 98.8), with no differences (p&gt;0.05) found for total cage activity (counts) (WT, 14935.42 ± 1799.6 vs. KO, 11860.83 ± 679.48), body weight (grams) (WT, 20.97 ± 0.76 vs. KO, 22.18 ± 0.80), or adiposity (arbitrary units) (WT, 5.18 ± 1.71 vs. KO, 2.12 ± 0.36). These results showing that high levels of endogenous muscle SLN expression in female mice influence whole-body metabolism even under chow-fed conditions, demonstrate a potential important sex difference in whole body physiology and metabolism. Natural Sciences and Engineering Research Council of Canada (NSERC) [grant number 311922-05 (to A.R.T.)] This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 550: Vascular And Muscle Recovery In Pre-clinical Model Of Peripheral Vascular Disease Using Intramuscular Estrogen Related Receptor Gamma Gene Therapy

Peripheral arterial disease (PAD) and critical limb ischemia (CLI) are caused by occlusion of blood vessels and characterized by muscle ischemia, weakness, and limb myopathy. Over 8-12 million Americans are affected by PAD, resulting in impaired mobility, increased cardiovascular risk, and limb amputation. Therapeutic strategies for simultaneously restoring blood flow, metabolism, and muscle recovery are currently lacking for PAD. We have previously shown in a transgenic mouse model that nuclear receptor Estrogen-related receptor gamma (ERRγ) is a central regulator of muscle metabolism and angiogenesis. Here, we investigated intramuscular (IM) gene therapy for PAD using AAV9-Esrrg in unilateral hindlimb ischemia (HLI) pre-clinical model. We first established in hindlimb muscles of C57Bl6/J mice that a single IM injection of 1X10^11 AAV9-Esrrg viral particles robustly increased ERRγ protein expression, resulting in induction of angiogenic and oxidative genes, higher capillary (CD31 immunostaining) density and SDH oxidative metabolic activity over AAV9-GFP injected control muscles. Subsequently, AAV9-Esrrg injection, 24 hours after HLI, increased ischemic neo-angiogenesis, markers of endothelial activation, and significantly improved blood flow recovery measured by laser Doppler flowmetry over AAV9-GFP injected controls. Moreover, ERRγ overexpression increased mitochondrial respiratory complex protein expression, which resulted in restored SDH oxidative metabolic capacity in ischemic muscle. More critically, AAV9-Esrrg restored myofibrillar size and mitigated ischemia-induced myopathy as revealed by myofiber size to number ratio quantification. In conclusion, we demonstrate that post-ischemic IM AAV9-Esrrg gene delivery rescues ischemic pathology by boosting metabolism and angiogenesis, underscoring Esrrg gene therapy or pharmacological activation as a highly promising strategy for treating PAD/CLI-related myopathy.

The role of 5′-adenosine monophosphate-activated protein kinase (AMPK) in skeletal muscle atrophy

As a key coordinator of metabolism, AMP-activated protein kinase (AMPK) is vitally involved in skeletal muscle maintenance. AMPK exerts its cellular effects through its function as a serine/threonine protein kinase by regulating many downstream targets and plays important roles in the development and growth of skeletal muscle. AMPK is activated by phosphorylation and exerts its function as a kinase in many processes, including synthesis and degradation of proteins, mitochondrial biogenesis, glucose uptake, and fatty acid and cholesterol metabolism. Skeletal muscle atrophy is a result of various diseases or disorders and is characterized by a decrease in muscle mass. The pathogenesis and therapeutic strategies of skeletal muscle atrophy are still under investigation. In this review, we discuss the role of AMPK in skeletal muscle metabolism and atrophy. We also discuss targeting AMPK for skeletal muscle treatment, including exercise, AMPK activators including 5-amino-4-imidazolecarboxamide ribonucleoside and metformin, and low-level lasers. These studies show the important roles of AMPK in regulating muscle metabolism and function; thus, the treatment of skeletal muscle atrophy needs to take into account the roles of AMPK.

Skeletal muscle HSF1 prevents insulin resistance by improving glucose utilization.

The regulation of muscle glucose utilization has significant potential for the treatment of type 2 diabetes mellitus (T2DM) and obesity. Heat shock factor 1 (HSF1) is involved in cellular metabolism and regulation of muscle metabolism. However, it is unclear how HSF1 regulates muscle glucose metabolism. In the present study, the development of obesity in mice was associated with HSF1 downregulation. Serum samples and muscle biopsies were obtained from obese and healthy humans. Fasting glucose and insulin levels and the homeostasis model assessment of insulin resistance value showed that obesity was associated with insulin resistance. The skeletal muscle level of HSF1 was decreased in obese and ob/ob mice. HSF1 was selectively over-expressed in the skeletal muscles of high fat diet (HFD)-fed mice. Muscle HSF1 over-expression successfully triggered glycolytic-to-oxidative myofiber switch and increased fatty acid metabolism and insulin sensitivity in the skeletal muscles of HFD-fed mice. Moreover, HSF1 improved energy expenditure and blocked muscle accumulation of triglycerides in HFD-fed mice. Consequently, muscle HSF1 mitigated the impaired muscle insulin signaling and insulin resistance in HFD-fed mice. In conclusion, T2DM and obesity in HFD-fed mice may be treated with selective HSF1-directed programming of exercise-like effects in skeletal muscle. These findings may aid the development of a new therapeutic approach for obesity and T2DM.

Determination of skeletal muscle mass by aspartate aminotransferase / alanine aminotransferase ratio, insulin and FSH in Chinese women with sarcopenia

Background:Sarcopenia is an age-related skeletal muscle disorder that involves a loss of muscle mass or strength and physiological function. Skeletal muscle deteriorates in both quantity and quality. The endocrine system is an important regulator of muscle metabolism. Therefore, we aimed to explore the relationship between biochemical markers and muscle mass in sarcopenia.Methods:We used the AWGS 2014 as the diagnostic criteria for sarcopenia, considering both the loss in muscle mass, muscle strength and physical performance. A total of 2837 elderly female participants over 50 years of age from the West China Health and Aging Trend (WCHAT) study were included. Insulin, glucose, 25(OH)VD, procalcitonin, alanine aminotransferase, aspartate aminotransferase, total protein, prealbumin, albumin, thyroid-stimulating hormone, free triiodothyronine, free tetraiodothyronine, triglycerides, cholesterol, high-density lipoprotein, very low-density lipoprotein, cortisol, and follicle-stimulating hormone were measured. Based on the findings of univariate analysis, multivariate regression and receiver operating characteristic (ROC) curves were established.Results:Participants with sarcopenia had significantly lower free triiodothyronine, insulin, total protein, albumin, prealbumin, albumin/prealbumin ratio (A/G), alanine aminotransferase, triglycerides, and very low-density lipoprotein concentrations (P < 0.05). Compared with those without sarcopenia, those with sarcopenia had significantly higher free tetraiodothyronine, cortisol, follicle-stimulating hormone (FSH), aspartate aminotransferase/alanine aminotransferase ratio (AST/ALT), and high-density lipoprotein concentrations (P < 0.05). Insulin (OR = 0.854), FSH (OR = 1.016), and the AST/ALT ratio (OR = 1.819) were independent risk factors for low muscle mass (P < 0.001). The AUC of insulin was the highest, followed by the AST/ALT ratio and FSH (0.691, 0.671, and 0.634, respectively), and the AUC of the mixture of the above three reached 0.736.Conclusion:In this cross-sectional study of elderly Chinese females aged over 50 years from the WCHAT, FSH, insulin, and AST/ALT ratio were associated with sarcopenia and risk factors for low muscle mass.

PGC-1β modulates catabolism and fiber atrophy in the fasting-response of specific skeletal muscle beds

ObjectiveSkeletal muscle is a pivotal organ for the coordination of systemic metabolism, constituting one of the largest storage site for glucose, lipids and amino acids. Tight temporal orchestration of protein breakdown in times of fasting has to be balanced with preservation of muscle mass and function. However, the molecular mechanisms that control the fasting response in muscle are poorly understood. MethodsWe now have identified a role for the peroxisome proliferator-activated receptor γ coactivator 1β (PGC-1β) in the regulation of catabolic pathways in this context in muscle-specific loss-of-function mouse models. ResultsMuscle-specific knockouts for PGC-1β experience mitigated muscle atrophy in fasting, linked to reduced expression of myostatin, atrogenes, activation of AMP-dependent protein kinase (AMPK) and other energy deprivation signaling pathways. At least in part, the muscle fasting response is modulated by a negative effect of PGC-1β on the nuclear factor of activated T-cells 1 (NFATC1). ConclusionsCollectively, these data highlight the complex regulation of muscle metabolism and reveal a new role for muscle PGC-1β in the control of proteostasis in fasting.

EFFECTS OF EXERCISE ON COGNITIVE FUNCTIONING AND MENTAL HEALTH: A MUSCLE - BRAIN CONNECTION

During the last decades, the benefits of regular exercise for brain health, particularly for cognition and mental health, have been well-reported by both observational and experimental human studies. Although many of these studies were focused on the effects of chronic exercise in cognitively impaired subjects, recent investigations have highlighted the role of exercise in improving cognitive abilities and preventing the decline of cognition across the lifespan in healthy individuals. On the other hand, significant evidence exists to suggest that exercise programs can improve treatment outcomes for different mental disorders, especially those that affect mood. However, the mechanisms of acute and chronic exerciseimproved brain function are still not completely known. In this context, it is important to consider that exercise induces muscle responses and adaptations that affect remote tissues. Like other secretory cells, myocytes produce cytokines and other peptides called myokines which exert an autocrine function in regulating muscle metabolism as well as a paracrine/endocrine regulatory function on distant organs, such as the gut, liver, and brain. Thus, the aim of this manuscript is to reinforce the potential of exercise as a useful tool to improve cognitive functioning and mental health and how muscle-brain crosstalk could play a key role in these exercise-related benefits.

Combined Treatment with Bojungikgi-Tang and Riluzole Regulates Muscle Metabolism and Dysfunction in the hSOD1G93A Mouse Model.

The progressive neurodegenerative disease, amyotrophic lateral sclerosis (ALS), is characterized by muscle weakness and atrophy owing to selective motoneuron degeneration. The anti-glutamatergic drug, riluzole (RZ), is the standard-of-care treatment for ALS. Bojungikgi-tang (BJIGT), a traditional herbal formula, improves motor function and prolongs the survival of mice with ALS. As ALS is a multicomplex disease, effective therapies must target multiple mechanisms. Here, we evaluated the efficacy of a BJIGT/RZ combination (5-week treatment) in 2-month-old hSOD1G93A mice with ALS. We performed quantitative polymerase chain reaction, Western blotting, immunohistochemistry, and enzyme activity assays. BJIGT/RZ significantly attenuated inflammation, autophagy, and metabolic and mitochondrial dysfunctions in the gastrocnemius (GC) compared with the control. It reduced the mRNA and protein levels of muscle denervation-related proteins and creatine kinase levels. The total creatine level was significantly higher in the BJIGT/RZ-treated GC. Moreover, after BJIGT/RZ treatment, the number of Nissl-stained motoneurons and choline acetyl transferase-positive neurons in the spinal cord significantly increased via the regulation of proinflammatory cytokines. Collectively, the BJIGT/RZ treatment was superior to single-drug treatments in alleviating multiple ALS-related pathological mechanisms in the ALS mouse model. Overall, BJIGT can serve as a dietary supplement and be combined with RZ to achieve superior therapeutic effects against ALS.

Sirtuin 3 overexpression preserves maximal sarco(endo)plasmic reticulum calcium ATPase activity in the skeletal muscle of mice subjected to high fat - high sucrose feeding.

Sarco(endo)plasmic reticulum calcium (Ca2+) ATPase (SERCA) transports Ca2+ in muscle. Impaired SERCA activity may contribute to diabetic myopathy. Sirtuin (SIRT) 3 regulates muscle metabolism and function; however, it is unknown if SIRT3 regulates muscle SERCA activity or acetylation. We determined if SIRT3 overexpression enhances SERCA activity in mouse gastrocnemius muscle and if SIRT3 overexpression preserves gastrocnemius SERCA activity in a model of type 2 diabetes, induced by high fat - high sucrose (HFHS) feeding. We also determined if the acetylation status of SERCA proteins in mouse gastrocnemius is altered by SIRT3 overexpression or HFHS feeding. Wild-type (WT) and SIRT3 transgenic (SIRT3TG) mice, overexpressing SIRT3 in skeletal muscle, were fed a standard or HFHS diet for 4 months. SIRT3TG and WT mice developed obesity and glucose intolerance after 4 months of HFHS feeding. SERCA Vmax was higher in gastrocnemius of SIRT3TG mice compared with WT mice. HFHS-fed mice had lower SERCA1a protein levels and lower SERCA Vmax in their gastrocnemius than control-fed mice. The decrease in SERCA Vmax in gastrocnemius muscle due to HFHS feeding was attenuated by SIRT3 overexpression in HFHS-fed SIRT3TG mice. SERCA1a and SERCA2a acetylation in mouse gastrocnemius was not altered by genotype or diet. These findings suggest SIRT3 overexpression improves SERCA function in mouse skeletal muscle.

Development of a multiplex assay to determine the expression of mitochondrial genes in human skeletal muscle.

What is the central question of this study? Can a custom-designed multiplex gene expression assay be used to quantify expression levels of a targeted group of mitochondrial genes in human skeletal muscle? What is the main finding and its importance? A custom-designed GeXP multiplex assay was developed, and the ability to accurately quantify expression of a targeted set of mitochondrial genes in human skeletal muscle was demonstrated. It holds distinct methodological and practical advantages over other commonly used quantification methods. Skeletal muscle is an important endocrine tissue demonstrating plasticity in response to external stimuli, including exercise and nutrition. Mitochondrial biogenesis is a common hallmark of adaptations to aerobic exercise training. Furthermore, altered expression of several genes implicated in the regulation of mitochondrial biogenesis, substrate oxidation and nicotinamide adenine dinucleotide (NAD+ ) biosynthesis following acute exercise underpins longer-term muscle metabolic adaptations. Gene expression is typically measured using real-time quantitative PCR platforms. However, interest has developed in the design of multiplex gene expression assays (GeXP) using the GenomeLab GeXP™ genetic analysis system, which can simultaneously quantify gene expression of multiple targets, holding distinct advantages in terms of throughput, limiting technical error, cost effectiveness, and quantifying gene co-expression. This study describes the development of a custom-designed GeXP assay incorporating the measurement of proposed regulators of mitochondrial biogenesis, substrate oxidation, and NAD+ biosynthetic capacity in human skeletal muscle and characterises the resting gene expression (overnight fasted and non-exercised) signature within a group of young, healthy, recreationally active males. The design of GeXP-based assays provides the capacity to more accurately characterise the regulation of a targeted group of genes with specific regulatory functions, a potentially advantageous development for future investigations of the regulation of muscle metabolism by exercise and/or nutrition.

Lower serum vitamin D in patients with idiopathic inflammatory myopathies is related to altered lipid metabolism in patients’ muscle cells

Idiopathic inflammatory myopathies/IIM are associated with muscle atrophy and metabolic dysfunction. Regular exercise improves muscle function and patients’ clinical state. Limited evidence points at low circulating vitamin D/vitD levels in IIM patients, which could contribute to metabolic dysfunction. Previously, we showed that altered lipid metabolism in muscle cells from IIM patients was normalized by 6-month training. Our aim was to assess (i) total & active/A (1,25-diOH) vitD in serum of patients with IIM before & after training intervention and of healthy controls, and (ii) associations between circulating vitD and lipid metabolism in patients’ cultured muscle cells. IIM patients underwent 6-month training (supervised training of activities of daily living 2x/week + individual home-based exercise). Serum total & A-vitD were assessed. Muscle Bergstrom biopsy (vastus lateralis) was performed in IIM patients before & after training (5F/2M, age 52.7±9.6 yrs, BMI 27.5±10.6 kg/m2) and in age/gender/BMI-matched sedentary healthy controls. Muscle cell cultures were established and exposed to 100µM palmitate (3 last days of differentiation). After 5 days of differentiation, vitD receptor mRNA (VDR, q-PCR), production of CO2 & β-oxidation intermediates (fat oxidation/FOx assay with [1-14C]-palmitate), and incorporation of labeled palmitate into lipids (thin layer chromatography) were measured in myotubes in vitro. Compared to controls, IIM patients had higher total and lower A-vitD levels before (p=0.055 & 0.009) and after (p=0.044 & 0.006) training. Training did not change serum vitD in IIM patients. VDR mRNA in myotubes was not modulated by IIM or training. However, 3-day palmitate tended to reduce VDR mRNA in myotubes in vitro (IIM before training & controls: p=0.06). Serum A-vitD was negatively associated with palmitate-induced changes in VDR mRNA (R=-0.598, p=0.011) and positively with incomplete FOx (R=0.587, p=0.005), total fatty acid/FA disposal (R=0.656, p=0.001), and % oxidative disposal from total FA disposal (R=0.573, p=0.007) in myotubes. Total vitD serum levels correlated negatively with incorporation of FA into diacylglycerols (R=-0.535, p=0.012) in myotubes. Patients with IIM displayed lower active and higher total vitamin D serum levels. Six-month training did not modulate vitamin D in serum and expression of its receptor in myotubes. Relationships of serum vitamin D levels with the expression of its receptor and parameters of lipid metabolism in muscle cells in vitro suggest the importance of vitamin D for muscle metabolic regulation in patients with IIM.