An isoflavone compound daidzein elicits myoblast differentiation and myotube growth

Potential of Lycii Radicis Cortex as an Ameliorative Agent for Skeletal Muscle Atrophy

Lycii Radicis Cortex (LRC) is a traditional medicine in East Asia with various beneficial effects, including antioxidant, anti-inflammatory, anti-tumor, anti-diabetic, and anti-depressant properties. However, its potential effects on skeletal muscle atrophy have not been studied. In this study, the protective effects of LRC extract (LRCE) on dexamethasone (DEX)-induced muscle atrophy were investigated in C2C12 myotubes and mice. We evaluated the effect of LRCE on improving muscle atrophy using a variety of methods, including immunofluorescence staining, quantitative polymerase chain reaction (qPCR), Western blot, measurements of oxidative stress, apoptosis, ATP levels, and muscle tissue analysis. The results showed that LRCE improved myotube diameter, fusion index, superoxide dismutase (SOD) activity, mitochondrial content, ATP levels, expression of myogenin and myosin heavy chain (MHC), and reduced reactive oxygen species (ROS) production in dexamethasone-induced C2C12 myotubes. LRCE also enhanced protein synthesis and reduced protein degradation in the myotubes. In mice treated with DEX, LRCE restored calf thickness, decreased mRNA levels of muscle-specific RING finger protein 1 (MuRF1) and atrogin-1, and increased insulin-like growth factor 1 (IGF-1) mRNA level. Moreover, LRCE also repaired gastrocnemius muscle atrophy caused by DEX. Although human studies are not available, various preclinical studies have identified potential protective effects of LRCE against muscle atrophy, suggesting that it could be utilized in the prevention and treatment of muscle atrophy.

A Lignan from Alnus japonica Activates Myogenesis and Alleviates Dexamethasone-induced Myotube Atrophy

To find inhibitors against skeletal muscle loss, we isolated a lignan compound ((-)-(2R,3R-1,4-O-diferuloylsecoisolarciresinol, DFS) from the stem of Alnus japonica. C2C12 myoblasts were treated with DFS during differentiation. To induce an in vitro atrophic condition, differentiated myotubes were treated with dexamethasone (a synthetic glucocorticoid). DFS (10 nM) increased expression levels of myogenic factors and the number of multi-nucleated myotubes expressing myosin heavy chain (MHC). The myogenic potential of DFS could be attributed to p38 MAPK activation. DFS also protected against dexamethasone-induced damage, showing increased expression of MHC and mammalian target of rapamycin (mTOR), a major anabolic factor. Under atrophic condition, the anti-myopathy effect of DFS was associated with inactivation of NF-κB signaling pathway and the subsequent suppression of muscle degradative E3 ligases and myostatin. DFS treatment also restored fast muscle fiber (type II a, II b, and II x), known to be susceptible to dexamethasone. These results indicate that DFS isolated from A. japonica can stimulate myogenesis via p38 MAPK activation and alleviate muscle atrophy by modulating the expression of genes associated with muscle protein anabolism/catabolism. Thus, we propose that DFS can be used as a pharmacological and nutraceutical agent for increasing muscle strength or protecting muscle loss.

Towards a More Realistic In Vitro Meat: The Cross Talk between Adipose and Muscle Cells

According to statistics and future predictions, meat consumption will increase in the coming years. Considering both the environmental impact of intensive livestock farming and the importance of protecting animal welfare, the necessity of finding alternative strategies to satisfy the growing meat demand is compelling. Biotechnologies are responding to this demand by developing new strategies for producing meat in vitro. The manufacturing of cultured meat has faced criticism concerning, above all, the practical issues of culturing together different cell types typical of meat that are partly responsible for meat’s organoleptic characteristics. Indeed, the existence of a cross talk between adipose and muscle cells has critical effects on the outcome of the co-culture, leading to a general inhibition of myogenesis in favor of adipogenic differentiation. This review aims to clarify the main mechanisms and the key molecules involved in this cross talk and provide an overview of the most recent and successful meat culture 3D strategies for overcoming this challenge, focusing on the approaches based on farm-animal-derived cells.

Ginsenoside Rg3 protects glucocorticoid‑induced muscle atrophy in vitro through improving mitochondrial biogenesis and myotube growth

Ginsenoside Rg3 (Rg3), amplified by iterative heating processing with fresh ginseng, has a broad range of pharmacological activities and improves mitochondrial biogenesis in skeletal muscle. However, thus far no study has examined how Rg3 affects myotube growth or muscle atrophy, to the best of the authors' knowledge. The present study was conducted to examine the myogenic effect of Rg3 on dexamethasone (DEX)‑induced myotube atrophy and the underlying molecular mechanisms. Rg3 activated Akt/mammalian target of rapamycin signaling to prevent DEX‑induced myotube atrophy thereby stimulating the expression of muscle‑specific genes, including myosin heavy chain and myogenin, and suppressing muscle‑specific ubiquitin ligases as demonstrated by immunoblotting and immunostaining assays. Furthermore, Rg3 efficiently prevented DEX‑triggered mitochondrial dysfunction of myotubes through peroxisome proliferator‑activated receptor‑γ coactivator1α activities and its mitochondrial biogenetic transcription factors, nuclear respiratory factor‑1 and mitochondrial transcription factor A. These were confirmed by immunoblotting, luciferase assays, RT‑qPCR and mitochondrial analysis measuring the levels of ROS, ATP and membrane potential. By providing a mechanistic insight into the effect of Rg3 on myotube atrophy, the present study suggested that Rg3 has potential as a therapeutic or nutraceutical remedy to intervene in muscle aging or diseases including cancer cachexia.

Nutrient weight against sarcopenia: regulation of the IGF-1/PI3K/Akt/FOXO pathway in quinoa metabolites

Sarcopenia is characterized by the loss of muscle mass and strength, and one of its major molecular mechanisms is muscle protein turnover. Quinoa, the grain-like food crop, is a health nutrient used to treat diseases that predispose individuals to muscle wasting, including cardiovascular disorders, diabetes mellitus, and cancer. Quinoa secondary metabolites have recently been demonstrated to regulate protein turnover (including protein synthesis and degradation), a main biological process within muscle cells, through diverse signals (such as the p38 MAPK, TNF-α, and IGF-1/PI3K/Akt/FOXO pathways). Here, we describe how quinoa functions in the main pathway of protein synthesis and degradation, screen promising pharmacological components in nutritional applications, and provide guidance for the effects of quinoa products in sarcopenia.

Polyphenols and Their Effects on Muscle Atrophy and Muscle Health

Skeletal muscle atrophy is the decrease in muscle mass and strength caused by reduced protein synthesis/accelerated protein degradation. Various conditions, such as denervation, disuse, aging, chronic diseases, heart disease, obstructive lung disease, diabetes, renal failure, AIDS, sepsis, cancer, and steroidal medications, can cause muscle atrophy. Mechanistically, inflammation, oxidative stress, and mitochondrial dysfunction are among the major contributors to muscle atrophy, by modulating signaling pathways that regulate muscle homeostasis. To prevent muscle catabolism and enhance muscle anabolism, several natural and synthetic compounds have been investigated. Recently, polyphenols (i.e., natural phytochemicals) have received extensive attention regarding their effect on muscle atrophy because of their potent antioxidant and anti-inflammatory properties. Numerous in vitro and in vivo studies have reported polyphenols as strongly effective bioactive molecules that attenuate muscle atrophy and enhance muscle health. This review describes polyphenols as promising bioactive molecules that impede muscle atrophy induced by various proatrophic factors. The effects of each class/subclass of polyphenolic compounds regarding protection against the muscle disorders induced by various pathological/physiological factors are summarized in tabular form and discussed. Although considerable variations in antiatrophic potencies and mechanisms were observed among structurally diverse polyphenolic compounds, they are vital factors to be considered in muscle atrophy prevention strategies.

Flavonoids: nutraceutical potential for counteracting muscle atrophy

Skeletal muscle plays a vital role in the conversion of chemical energy into physical force. Muscle atrophy, characterized by a reduction in muscle mass, is a symptom of chronic disease (cachexia), aging (sarcopenia), and muscle disuse (inactivity). To date, several trials have been conducted to prevent and inhibit muscle atrophy development; however, few interventions are currently available for muscle atrophy. Recently, food ingredients, plant extracts, and phytochemicals have received attention as treatment sources to prevent muscle wasting. Flavonoids are bioactive polyphenol compounds found in foods and plants. They possess diverse biological activities, including anti-obesity, anti-diabetes, anti-cancer, anti-oxidation, and anti-inflammation. The effects of flavonoids on muscle atrophy have been investigated by monitoring molecular mechanisms involved in protein turnover, mitochondrial activity, and myogenesis. This review summarizes the reported effects of flavonoids on sarcopenia, cachexia, and disuse muscle atrophy, thus, providing an insight into the understanding of the associated molecular mechanisms.

Endophytic Fungi of Native Salvia abrotanoides Plants Reveal High Taxonomic Diversity and Unique Profiles of Secondary Metabolites

Endophytic fungi are often embedded in their host's metabolic networks, which can result in alterations of metabolite production and higher amounts of active compounds in medicinal plants. This study reports the occurrence, diversity, and secondary metabolite profiles of endophytic fungi isolated from Salvia abrotanoides plants obtained from three geographically distinct sites in Iran. A total of 56 endophytic fungi were isolated from roots and leaves of S. abrotanoides; site-specificity and root-dominated colonization was found to be a general characteristic of the endophytes. Based on molecular identification, the endophytic fungi were classified into 15 genera. Mycelial extracts of these isolates were subjected to high-resolution mass spectrometry analyses and revealed a broad spectrum of secondary metabolites. Our results demonstrated that Penicillium canescens, P. murcianum, Paraphoma radicina, and Coniolariella hispanica are producers of cryptotanshinone, which is a main bioactive compound of S. abrotanoides. Moreover, it was shown that it can be produced independent of the host plant. The effect of exogenous gibberellin on S. abrotanoides and endophytic fungi was shown to have a positive effect on increasing the cryptotanshinone production in the plant as well as in endophytic fungi cultivated under axenic conditions. Our findings provide further evidence that endophytic fungi play an important role in the production plant bioactive metabolites. Moreover, they provide an exploitable basis to increase cryptotanshinone production in S. abrotanoides.

PRMT7 methylates and suppresses GLI2 binding to SUFU thereby promoting its activation

Cellular senescence is implicated in aging or age-related diseases. Sonic hedgehog (Shh) signaling, an inducer of embryonic development, has recently been demonstrated to inhibit cellular senescence. However, the detailed mechanisms to activate Shh signaling to prevent senescence is not well understood. Here, we demonstrate that Protein arginine methyltransferase 7 (PRMT7) promotes Shh signaling via GLI2 methylation which is critical for suppression of cellular senescence. PRMT7-deficient mouse embryonic fibroblasts (MEFs) exhibited a premature cellular senescence with accompanied increase in the cell cycle inhibitors p16 and p21. PRMT7 depletion results in reduced Shh signaling activity in MEFs while PRMT7 overexpression enhances GLI2-reporter activities that are sensitive to methylation inhibition. PRMT7 interacts with and methylates GLI2 on arginine residues 225 and 227 nearby a binding region of SUFU, a negative regulator of GLI2. This methylation interferes with GLI2-SUFU binding, leading to facilitation of GLI2 nuclear accumulation and Shh signaling. Taken together, these data suggest that PRMT7 induces GLI2 methylation, reducing its binding to SUFU and increasing Shh signaling, ultimately leading to prevention of cellular senescence.

Bioactivity of dietary polyphenols: The role of metabolites

A polyphenol-rich diet protects against chronic pathologies by modulating numerous physiological processes, such as cellular redox potential, enzymatic activity, cell proliferation and signaling transduction pathways. However, polyphenols have a low oral bioavailability mainly due to an extensive biotransformation mediated by phase I and phase II reactions in enterocytes and liver but also by gut microbiota. Despite low oral bioavailability, most polyphenols proved significant biological effects which brought into attention the low bioavailability/high bioactivity paradox. In recent years, polyphenol metabolites have attracted great interest as many of them showed similar or higher intrinsic biological effects in comparison to the parent compounds. There is a huge body of literature reporting on the biological functions of polyphenol metabolites generated by phase I and phase II metabolic reactions and gut microbiota-mediated biotransformation. In this respect, the review highlights the pharmacokinetic fate of the major dietary polyphenols (resveratrol, curcumin, quercetin, rutin, genistein, daidzein, ellagitannins, proanthocyanidins) in order to further address the efficacy of biometabolites as compared to parent molecules. The present work strongly supports the contribution of metabolites to the health benefits of polyphenols, thus offering a better perspective in understanding the role played by dietary polyphenols in human health.

Transcriptomics-Related Mechanisms of Supplementing Laying Broiler Breeder Hens with Dietary Daidzein to Improve the Immune Function and Growth Performance of Offspring

Daidzein (DA) is an isoflavone that is primarily extracted from soy plants. This study evaluated the effects of supplementing laying broiler breeder hens with dietary DA on the immune function and growth performance of their offspring and the underlying mechanism. A total of 720 breeders were divided into three treatment groups that were fed either a control diet (CON), a DA-low-supplemented diet (DLS, CON+20 mg/kg DA), or a DA-high-supplemented diet (DHS, CON+100 mg/kg DA) for 8 weeks, and eggs were collected for hatching during the final week. The broiler offspring received a basal diet for 42 days, and blood, livers, and immune organs were collected at 21 and 42 days of age. DLS treatment promoted embryonic development and increased growth hormone levels, body weight, feed intake, and carcass traits on days 21 and 42 of broilers. Additionally, the IgA and IgG concentrations, antibody titers, and antioxidant capacity of broilers were increased at 21 days of age, and B lymphocyte differentiation was increased at 42 days. Besides, DLS treatment upregulated the expression of genes related to embryonic and muscle development in offspring and regulated mitogen-activated protein kinase (MAPK), transforming growth factor beta (TGF-β), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and Toll-like receptor signaling. DHS treatment decreased the percentage of abdominal fat in the broilers at 42 days, but it did not significantly affect embryonic development, growth performance, or IgA and IgG concentrations. In summary, providing dietary DA supplementation at 20 mg/kg to broiler breeders can improve their immune function and growth performance.