Background Skeletal muscle fat infiltration is a common feature during ageing, obesity and several myopathies associated with muscular dysfunction and sarcopenia. However, the regulatory mechanisms of intramuscular adipogenesis and strategies to reduce fat infiltration in muscle remain unclear. Here, we identified the growth arrest and DNA damage‐inducible alpha (GADD45A), a stress‐inducible histone folding protein, as a critical regulator of intramuscular fat (IMAT) infiltration. Methods To explore the role of GADD45A on IMAT infiltration and muscle regeneration, the gain or loss function of GADD45A in intramuscular preadipocytes was performed. The adipocyte‐specific GADD45A knock‐in (KI) mice and high IMAT‐infiltrated muscle model by glycerol injection (50 μL of 50% v/v GLY) were generated. RNA‐sequencing, histological changes, gene expression, lipid metabolism, mitochondrial function and the effect of dietary factor epigallocatechin‐3‐gallate (EGCG) treatment (100 mg/kg) on IMAT infiltration were studied. Results The unbiased transcriptomics data analysis indicated that GADD45A expression positively correlates with IMAT infiltration and muscle metabolic disorders in humans (correlation: young vs. aged people, Gadd45a and Cebpa, r2 = 0.20, P < 0.05) and animals (correlation: wild‐type [WT] vs. mdx mice, Gadd45a and Cebpa, r2 = 0.38, P < 0.05; NaCl vs. GLY mice, Gadd45a and Adipoq/Fabp4, r2 = 0.80/0.71, both P < 0.0001). In vitro, GADD45A overexpression promotes intramuscular preadipocyte adipogenesis, upregulating the expression of adipogenic genes (Ppara: +47%, Adipoq: +28%, P < 0.001; Cebpa: +135%, Fabp4: +16%, P < 0.01; Pparg: +66%, Leptin: +77%, P < 0.05). GADD45A knockdown robustly decreased lipid accumulation (Pparg: −57%, Adipoq: −35%, P < 0.001; Fabp4: −37%, P < 0.01; Leptin: −28%, P < 0.05). GADD45A KI mice exhibit inhibited skeletal muscle regeneration (myofibres: −40%, P < 0.01) and enhanced IMAT infiltration (adipocytes: +20%, P < 0.05). These KI mice have impaired exercise endurance and mitochondrial function. Mechanistically, GADD45A affects ATP synthase F1 subunit alpha (ATP5A1) ubiquitination degradation (ubiquitinated ATP5A1, P < 0.001) by recruiting the E3 ubiquitin ligase TRIM25, which decreases ATP synthesis (ATP production: −23%, P < 0.01) and inactivates the cAMP/PKA/LKB1 signalling pathway (cAMP: −36%, P < 0.01; decreased phospho‐PKA and phospho‐LKB1 protein content, P < 0.01). The dietary factor EGCG can protect against muscle fat infiltration (triglyceride: −64%, P < 0.05) via downregulating GADD45A (decreased GADD45A protein content, P < 0.001). Conclusions Our findings reveal a crucial role of GADD45A in regulating muscle repair and fat infiltration and suggest that inhibition of GADD45A by EGCG might be a potential strategy to combat fat infiltration and its associated muscle dysfunction.
Deoxynivalenol (DON) is one of the main types of B trichothecenes, and it causes health‐related issues in humans and animals and imposes considerable challenges to food and feed safety globally each year. This review investigates the global hazards of DON, describes the occurrence of DON in food and feed in different countries, and systematically uncovers the mechanisms of the various toxic effects of DON. For DON pollution, many treatments have been reported on the degradation of DON, and each of the treatments has different degradation efficacies and degrades DON by a distinct mechanism. These treatments include physical, chemical, and biological methods and mitigation strategies. Biodegradation methods include microorganisms, enzymes, and biological antifungal agents, which are of great research significance in food processing because of their high efficiency, low environmental hazards, and drug resistance. And we also reviewed the mechanisms of biodegradation methods of DON, the adsorption and antagonism effects of microorganisms, and the different chemical transformation mechanisms of enzymes. Moreover, nutritional mitigation including common nutrients (amino acids, fatty acids, vitamins, and microelements) and plant extracts was discussed in this review, and the mitigation mechanism of DON toxicity was elaborated from the biochemical point of view. These findings help explore various approaches to achieve the best efficiency and applicability, overcome DON pollution worldwide, ensure the sustainability and safety of food processing, and explore potential therapeutic options with the ability to reduce the deleterious effects of DON in humans and animals.
Melatonin has been reported to play crucial roles in regulating meat quality, improving reproductive properties and maintaining intestinal health in animal production, but whether it regulates skeletal muscle development in weaned piglet is rarely studied. This study was conducted to investigate the effects of melatonin on growth performance, skeletal muscle development and lipid metabolism in animals by intragastric administration of melatonin solution. Twelve 28-day-old DLY (Duroc × Landrace × Yorkshire) weaned piglets with similar body weight were randomly divided into two groups: control group and melatonin group. The results showed that melatonin supplementation for 23 days had no effect on growth performance, but significantly reduced serum glucose content (P<0.05). Remarkably, melatonin increased longissimus dorsi muscle (LDM) weight, eye muscle area and decreased the liver weight in weaned piglets (P<0.05). In addition, the cross-sectional area of muscle fibers was increased (P<0.05), while triglyceride (TG) levels were decreased in LDM and psoas major muscle (PMM) by melatonin treatment (P<0.05). Transcriptome sequencing showed melatonin induced the expression of genes related to skeletal muscle hypertrophy and fatty acid oxidation. Enrichment analysis indicated that melatonin regulated cholesterol metabolism, protein digestion and absorption and mitophagy signaling pathways in muscle. Gene set enrichment analysis (GSEA) also confirmed the effects of melatonin on skeletal muscle development and mitochondrial structure and function. Moreover, quantitative real-time polymerase chain reaction (qPCR) analysis revealed that melatonin supplementation elevated the gene expression of cell differentiation and muscle fiber development, including paired box 7 (PAX7), myogenin (MYOG), myosin heavy chain (MYHC) ⅡA and MYHC ⅡB (P<0.05), which was accompanied by increased insulin like growth factor 1 (IGF1) and insulin like growth factor binding protein 5 (IGFBP5) expression in LDM (P<0.05). Additionally, melatonin regulated lipid metabolism and activated mitochondrial function in muscle by increasing the mRNA abundance of cytochrome c oxidase subunit 6A (COX6A), COX5B and carnitine palmitoyltransferase 2 (CPT2) and decreasing the mRNA expression of peroxisome proliferator activated receptor gamma (PPARG), Acetyl-CoA carboxylase (ACC) and fatty acid binding protein 4 (FABP4) (P<0.05). Together, our results suggest that melatonin could promote skeletal muscle growth and muscle fiber hypertrophy, improve mitochondrial function and decrease fat deposition in muscle.
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