Astragalus polysaccharide regulates brown adipogenic differentiation through miR-1258-5p-modulated cut-like homeobox 1 expression

Guanidinoacetic acid ameliorates hepatic steatosis and inflammation and promotes white adipose tissue browning in middle-aged mice with high-fat-diet-induced obesity

Guanidinoacetic acid (GAA) is a naturally occurring amino acid derivative that plays a critical role in energy metabolism. In recent years, a growing body of evidence has emerged supporting the importance of GAA in metabolic dysfunction. Hence, we aimed to investigate the effects of GAA on hepatic and adipose tissue metabolism, as well as systemic inflammatory responses in obese middle-aged mice models and attempted to explore the underlying mechanism. We found that dietary supplementation of GAA inhibited inguinal white adipose tissue (iWAT) hypertrophy in high-fat diet (HFD)-fed mice. In addition, GAA supplementation observably decreased the levels of some systemic inflammatory factors, including IL-4, TNF-α, IL-1β, and IL-6. Intriguingly, GAA supplementation ameliorated hepatic steatosis and lipid deposition in HFD-fed mice, which was revealed by decreased levels of TG, TC, LDL-C, PPARγ, SREBP-1c, FASN, ACC, FABP1, and APOB and increased levels of HDL-C in the liver. Moreover, GAA supplementation increased the expression of browning markers and mitochondrial-related genes in the iWAT. Further investigation showed that dietary GAA promoted the browning of the iWAT via activating the AMPK/Sirt1 signaling pathway and might be associated with futile creatine cycling in obese mice. These results indicate that GAA has the potential to be used as an effective ingredient in dietary interventions and thus may play an important role in ameliorating and preventing HFD-induced obesity and related metabolic diseases.

Sea buckthorn oil regulates primary myoblasts proliferation and differentiation in vitro

Skeletal muscle is the main edible part of meat products, and its development directly affects the yield and palatability of meat. Sea buckthorn oil (SBO) contains plenty of bioactive substances and has been recognized as a potential functional food product. The study aimed to explore the effects and possible mechanisms of SBO on sheep primary myoblast proliferation and myogenic differentiation. The results implied that SBO exhibited a pro-proliferative effect on primary myoblasts, along with up-regulated proliferating cell nuclear antigen (PCNA) and Cyclin D1/cyclin-dependent kinase 4 (CDK4) abundances. And, SBO promoted myotube formation by increasing the expression of myogenin. Meanwhile, we found that SBO inhibited the expression of miRNA-292a. Moreover, the regulatory effect of SBO on myogenic differentiation of myoblasts was attenuated by miRNA-292a mimics. Of note, SBO activated protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway and augmented glucose uptake and glucose transporter 4 (GLUT4) content, which might be attributed to AMP-activated protein kinase (AMPK) activation. Additionally, the results were shown that SBO increased the abundance of antioxidative enzymes, including glutathione peroxidase 4 (Gpx4) and catalase. In summary, these data suggested that SBO regulated the proliferation and myogenic differentiation of sheep primary myoblasts in vitro, which might potentiate the application of SBO in muscle growth.

Guanidinoacetic Acid Attenuates Adipogenesis through Regulation of miR-133a in Sheep

Guanidinoacetic acid (GAA) is an amino acid derivative, previously described in the skeletal muscle of vertebrates, that serves as an important regulator of cellular bioenergetics and has been widely used as a feed additive. Nevertheless, the effect of GAA on adipose tissue growth remains unclear. Here, we hypothesized that dietary GAA negatively affected adipose tissue development in lambs. Lambs were individually fed diets with (0.09%) or without GAA for 70 d ad libitum, and the subcutaneous adipose tissues were sampled for analysis. The results showed that dietary GAA supplementation decreased the girth rib (GR) value (p < 0.01) of lamb carcasses. Both real-time PCR and Western blot analysis suggested that dietary GAA inhibited the expression of adipogenic markers, including peroxisome proliferator-activated receptor γ (PPARγ, p < 0.05), CCAAT/enhancer-binding protein α (C/EBPα, p < 0.01) and sterol-regulatory-element-binding protein 1c (SREBP1C, p < 0.01) in subcutaneous adipose tissue. In vitro, GAA inhibited sheep stromal vascular fraction (SVF) cell proliferation, which was associated with downregulation of proliferating cell nuclear antigen (PCNA, p < 0.05), cyclin-dependent kinase 4 (CDK 4, p < 0.05) and cyclin D1 (p < 0.01). GAA suppressed adipogenesis of SVF cells. Furthermore, miRNA sequencing revealed that GAA affected the miRNA expression profile, and real-time PCR analysis confirmed that miR-133a expression in both subcutaneous adipose tissue and SVF cell was downregulated by GAA. Meanwhile, miR-133a promoted adipogenic differentiation of SVF cells by targeting Sirt1. miR-133a mimics alleviated the inhibitory effect of GAA on SVF cells' adipogenic differentiation. In summary, GAA attenuated adipogenesis of sheep SVF cells, which might occur through miR-133a-modulated Sirt1 expression.

Astragalus polysaccharide promotes sheep satellite cell differentiation by regulating miR-133a through the MAPK/ERK signaling pathway

Astragalus polysaccharide (APS) possesses extensive biological activities, pharmacological effects, and anti-fatigue function. MiR-133a is a specifically expressed miRNA in skeletal muscle that participates in the regulation of myoblast proliferation and differentiation. However, little is known about the role of APS in the development of sheep skeletal muscle. In this study, we aimed to investigate the underlying mechanism of APS and miR-133a on the differentiation of sheep skeletal muscle satellite cells (SMSCs) and the regulatory relationship between APS and miR-133a. The results suggested that APS plays a positive regulatory role in the proliferation and differentiation of sheep SMSCs. Moreover, miR-133a significantly promotes SMSC differentiation and the activity of the MAPK/ERK signaling pathway. Importantly, we found that APS function requires the mediation of miR-133a in the differentiation of sheep SMSCs. Taken together, our results indicate that APS accelerates SMSC differentiation by regulating miR-133a via the MAPK/ERK signaling pathway in sheep.

Managing metabolic diseases: The roles and therapeutic prospects of herb-derived polysaccharides

Metabolic diseases have become a public health problem worldwide. Effective, novel and natural therapies are urgently needed to treat metabolic diseases. As natural bioactive compounds, polysaccharides have many physiological and medicinal properties. Recently, herb-derived polysaccharides have shown beneficial effects in the treatment of metabolic diseases, but the underlying mechanisms remain unclear. This review comprehensively summarizes the pharmacological progress and clinical evidence of herb-derived polysaccharides in the treatment of three metabolic diseases, namely type 2 diabetes mellitus, nonalcoholic fatty liver disease and obesity, and more importantly, discusses the molecular mechanism involved. Existing evidence has proved that herb-derived polysaccharides can maintain glucose homeostasis, promote insulin secretion, improve insulin resistance, reduce weight gain and hepatic steatosis, inhibit lipogenesis, alleviate oxidative stress and inflammation, and improve gut microbiota disorders in rodents with metabolic diseases. Notably, so far, human clinical trials of herb-derived polysaccharides for these three metabolic diseases remain rare. All in all, herb-derived polysaccharides may have good potential as drug candidates for the prevention and management of metabolic diseases. More high-quality clinical trials are needed to further validate its effectiveness and safety in human subjects.

The Interaction between Mushroom Polysaccharides and Gut Microbiota and Their Effect on Human Health: A Review

Mushroom polysaccharides are a kind of biological macromolecule extracted from the fruiting body, mycelium or fermentation liquid of edible fungi. In recent years, the research on mushroom polysaccharides for alleviating metabolic diseases, inflammatory bowel diseases, cancers and other symptoms by changing the intestinal microenvironment has been increasing. Mushroom polysaccharides could promote human health by regulating gut microbiota, increasing the production of short-chain fatty acids, improving intestinal mucosal barrier, regulating lipid metabolism and activating specific signaling pathways. Notably, these biological activities are closely related to the molecular weight, monosaccharide composition and type of the glycosidic bond of mushroom polysaccharide. This review aims to summarize the latest studies: (1) Regulatory effects of mushroom polysaccharides on gut microbiota; (2) The effect of mushroom polysaccharide structure on gut microbiota; (3) Metabolism of mushroom polysaccharides by gut microbiota; and (4) Effects of mushroom polysaccharides on gut microbe-mediated diseases. It provides a theoretical basis for further exploring the mechanism of mushroom polysaccharides for regulating gut microbiota and gives a reference for developing and utilizing mushroom polysaccharides as promising prebiotics in the future.