N⁶-methyladenosine (m⁶A), the most abundant internal modification on mRNAs in eukaryotes, play roles in adipogenesis. However, the underlying mechanism remains largely unclear. Here, we show that m⁶A plays a critical role in regulating macroautophagy/autophagy and adipogenesis through targeting Atg5 and Atg7. Mechanistically, knockdown of FTO, a well-known m⁶A demethylase, decreased the expression of ATG5 and ATG7, leading to attenuation of autophagosome formation, thereby inhibiting autophagy and adipogenesis. We proved that FTO directly targeted Atg5 and Atg7 transcripts and mediated their expression in an m⁶A-dependent manner. Further study identified that Atg5 and Atg7 were the targets of YTHDF2 (YTH N6-methyladenosine RNA binding protein 2). Upon FTO silencing, Atg5 and Atg7 transcripts with higher m⁶A levels were captured by YTHDF2, which resulted in mRNA degradation and reduction of protein expression, thus alleviating autophagy and adipogenesis. Furthermore, we generated an adipose-selective fto knockout mouse and find that FTO deficiency decreased white fat mass and impairs ATG5- and ATG7-dependent autophagy in vivo. Together, these findings unveil the functional importance of the m⁶A methylation machinery in autophagy and adipogenesis regulation, which expands our understanding of such interplay that is essential for development of therapeutic strategies in the prevention and treatment of obesity. Abbreviations: 3-MA: 3-methyladenine; ACTB: actin, beta; ATG: autophagy-related; Baf A1: bafilomycin A₁; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; CEBPB: CCAAT/enhancer binding protein (C/EBP), beta; FABP4: fatty acid binding protein 4, adipocyte; FTO: fat mass and obesity associated; HFD: high-fat diet; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MAP1LC3B/LC3: microtubule-associated protein 1 light chain 3 beta; m⁶A: N⁶-methyladenosine; MEFs: mouse embryo fibroblasts; MeRIP-qPCR: methylated RNA immunoprecipitation-qPCR; PPARG: peroxisome proliferator activated receptor gamma; RIP: RNA-immunoprecipitation; SAT: subcutaneous adipose tissue; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; ULK1: unc-51 like kinase 1; VAT: visceral adipose tissue; WAT: white adipose tissue; YTHDF: YTH N6-methyladenosine RNA binding protein

DNA N⁶-methyldeoxyadenosine (6mA) is a well-known prokaryotic DNA modification that has been shown to exist and play epigenetic roles in eukaryotic DNA. Here we report that 6mA accumulates up to ∼0.1–0.2% of total deoxyadenosine during early embryogenesis of vertebrates, but diminishes to the background level with the progression of the embryo development. During this process a large fraction of 6mAs locate in repetitive regions of the genome.

As a family of cationic host defense peptides, defensins are mainly synthesized by Paneth cells, neutrophils, and epithelial cells, contributing to host defense. Their biological functions in innate immunity, as well as their structure and activity relationships, along with their mechanisms of action and therapeutic potential, have been of great interest in recent years. To highlight the key research into the role of defensins in human and animal health, we first describe their research history, structural features, evolution, and antimicrobial mechanisms. Next, we cover the role of defensins in immune homeostasis, chemotaxis, mucosal barrier function, gut microbiota regulation, intestinal development and regulation of cell death. Further, we discuss their clinical relevance and therapeutic potential in various diseases, including infectious disease, inflammatory bowel disease, diabetes and obesity, chronic inflammatory lung disease, periodontitis and cancer. Finally, we summarize the current knowledge regarding the nutrient-dependent regulation of defensins, including fatty acids, amino acids, microelements, plant extracts, and probiotics, while considering the clinical application of such regulation. Together, the review summarizes the various biological functions, mechanism of actions and potential clinical significance of defensins, along with the challenges in developing defensins-based therapy, thus providing crucial insights into their biology and potential clinical utility.

Corn and soybean meal (SBM) are two of the most common feed ingredients used in pig feeds. However, a variety of antinutritional factors (ANFs) present in corn and SBM can interfere with the bioavailability of nutrients and have negative health effects on the pigs. In the present study, two-stage fermentation using Bacillus subtilis followed by Enterococcus faecium was carried out to degrade ANFs and improve the nutritional quality of corn and SBM mixed feed. Furthermore, the microbial composition and in vitro nutrient digestibility of inoculated mixed feed were determined and compared those of the uninoculated controls. During the fermentation process, B. subtilis and lactic acid bacteria (LAB) were the main dominant bacteria in the solid-state fermented inoculated feed, and fermentation produced a large amount of lactic acid (170 mmoL/kg), which resulted in a lower pH (5.0 vs. 6.4) than the fermented uninoculated feed. The amounts of soybean antigenic proteins (β-conglycinin and glycinin) in mixed feed were significantly decreased after first-stage fermentation with B. subtilis. Inoculated mixed feed following two-stage fermentation contained greater concentratioin of crude protein (CP), ash and total phosphorus (P) compared to uninoculated feed, whereas the concentrations of neutral detergent fiber (NDF), hemicellulose and phytate P in fermendted inoculated feed declined (P < 0.05) by 38%, 53%, and 46%, respectively. Notably, the content of trichloroacetic acid soluble protein (TCA-SP), particularly that of small peptides and free amino acids (AA), increased 6.5 fold following two-stage fermentation. There was no difference in the total AA content between fermented inoculated and uninoculated feed. However, aromatic AAs (Phe and Tyr) and Lys in inoculated feed increased, and some polar AAs, including Arg, Asp, and Glu, decreased compared with the uninoculated feed. In vitro dry matter and CP digestibility of inoculated feed improved (P < 0.05) compared with the uninoculated feed. Our results suggest that two-stage fermentation using B. subtilis followed by E. faecium is an effective approach to improve the quality of corn-soybean meal mixed feed.

The gut microbiota is comprised of a diverse array of microorganisms that interact with immune system and exert crucial roles for the health. Changes in the gut microbiota composition and functionality are associated with multiple diseases. As such, mobilizing a rapid and appropriate antimicrobial response depending on the nature of each stimulus is crucial for maintaining the balance between homeostasis and inflammation in the gut. Major players in this scenario are antimicrobial peptides (AMP), which belong to an ancient defense system found in all organisms and participate in a preservative co-evolution with a complex microbiome. Particularly increasing interactions between AMP and microbiota have been found in the gut. Here, we focus on the mechanisms by which AMP help to maintain a balanced microbiota and advancing our understanding of the circumstances of such balanced interactions between gut microbiota and host AMP. This review aims to provide a comprehensive overview on the interplay of diverse antimicrobial responses with enteric pathogens and the gut microbiota, which should have therapeutic implications for different intestinal disorders.

Intestinal permeability plays a critical role in the etiopathogenesis of ulcerative colitis. Defensins, including porcine β-defensin (pBD)2, are crucial antimicrobial peptides for gut protection owing to their antibacterial and immunomodulatory activities. The purpose of this study was to investigate the protective effects of pBD2 on mucosal injury and the disruption of the epithelial barrier during the pathological process of dextran sodium sulfate (DSS)–induced colitis. The effects and mechanism of pBD2 were evaluated both using a DSS-induced C57BL/6 mouse model and, in vitro, using Caco-2 and RAW264.7 cells. DSS-induced colitis was characterized by higher disease activity index, shortened colon length, elevated activities of myeloperoxidase and eosinophil peroxidase, histologic evidence of inflammation, and increased expression levels of TNF-α, IL-6, and IL-8. pBD2 increased the expression of zonula occludens-1, zonula occludens-2, claudin-1, mucin-1, and mucin-2 mRNA and proteins, and it decreased permeability to FITC-D, as well as apoptosis, in DSS-treated mice. pBD2 also decreased inflammatory infiltrates of the colon epithelium. In Caco-2 cells, pBD2 increased transepithelial electrical resistance and mucin mRNA expression, and it decreased the permeability of FITC-D while preserving the structural integrity of the tight junctions. The effects of pBD2 appeared to be through upregulation of the expression of genes associated with tight junctions and mucins, and by suppressing DSS-induced increases in inflammation, inducible NO synthase, cyclooxygenase-2, and apoptosis. These results show that pBD2 improves DSS-induced changes in mucosal lesions and paracellular permeability, possibly by affecting the activation of NF-κB signaling. The present study demonstrates that intrarectal administration of pBD2 may be a novel preventive option for ulcerative colitis.