In this study, exosomes from cooked meat were extracted by ultra-high-speed centrifugation. Approximately 80% of exosome vesicles were within 20–200 nm. In addition, the surface biomarkers of isolated exosomes were evaluated using flow cytometry. Further studies showed the exosomal microRNA profiles were different among cooked porcine muscle, fat and liver. Cooked pork-derived exosomes were chronically administered to ICR mice by drinking for 80 days. The mice plasma levels of miR-1, miR-133a-3p, miR-206 and miR-99a were increased to varying degrees after drinking exosome enriched water. Furthermore, GTT and ITT results confirmed an abnormal glucose metabolism and insulin resistance in mice. Moreover, the lipid droplets were significantly increased in the mice liver. A transcriptome analysis performed with mice liver samples identified 446 differentially expressed genes (DEGs). Functional enrichment analysis found that DEGs were enriched in metabolic pathways. Overall, the results suggest that microRNAs derived form cooked pork may function as a critical regulator of metabolic disorder in mice.
Background Increasing evidence shows that tRNA‐derived small RNAs (tsRNAs) are not only by‐products of transfer RNAs, but they participate in numerous cellular metabolic processes. However, the role of tsRNAs in skeletal muscle regeneration remains unknown. Methods Small RNA sequencing revealed the relationship between tsRNAs and skeletal muscle injury. The dynamic expression level of 5'tiRNA‐Gly after muscle injury was confirmed by real‐time quantitative PCR (q‐PCR). In addition, q‐PCR, flow cytometry, the 5‐ethynyl‐2'‐deoxyuridine (Edu), cell counting kit‐8, western blotting and immunofluorescence were used to explore the biological function of 5'tiRNA‐Gly. Bioinformatics analysis and dual‐luciferase reporter assay were used to further explore the mechanism of action under the biological function of 5'tiRNA‐Gly. Results Transcriptome analysis revealed that tsRNAs were significantly enriched during inflammatory response immediately after muscle injury. Interestingly, we found that 5'tiRNA‐Gly was significantly up‐regulated after muscle injury (P < 0.0001) and had a strong positive correlation with inflammation in vivo. In vitro experiments showed that 5'tiRNA‐Gly promoted the mRNA expression of proinflammatory cytokines (IL‐1β, P = 0.0468; IL‐6, P = 0.0369) and the macrophages of M1 markers (TNF‐α, P = 0.0102; CD80, P = 0.0056; MCP‐1, P = 0.0002). On the contrary, 5'tiRNA‐Gly inhibited the mRNA expression of anti‐inflammatory cytokines (IL‐4, P = 0.0009; IL‐10, P = 0.0007; IL‐13, P = 0.0008) and the mRNA expression of M2 markers (TGF‐β1, P = 0.0016; ARG1, P = 0.0083). Flow cytometry showed that 5'tiRNA‐Gly promoted the percentage of CD86+ macrophages (16%, P = 0.011) but inhibited that of CD206+ macrophages (10.5%, P = 0.012). Immunofluorescence showed that knockdown of 5'tiRNA‐Gly increased the infiltration of M2 macrophages to the skeletal muscles (13.9%, P = 0.0023) and inhibited the expression of Pax7 (P = 0.0089) in vivo. 5'tiRNA‐Gly promoted myoblast the expression of myogenic differentiation marker genes (MyoD, P = 0.0002; MyoG, P = 0.0037) and myotube formation (21.3%, P = 0.0016) but inhibited the positive rate of Edu (27.7%, P = 0.0001), cell viability (22.6%, P = 0.003) and the number of myoblasts in the G2 phase (26.3%, P = 0.0016) in vitro. Mechanistically, we found that the Tgfbr1 gene is a direct target of 5'tiRNA‐Gly mediated by AGO1 and AGO3. 5'tiRNA‐Gly dysregulated the expression of downstream genes related to inflammatory response, activation of satellite cells and differentiation of myoblasts through the TGF‐β signalling pathway by targeting Tgfbr1. Conclusions These results reveal that 5'tiRNA‐Gly potentially regulated skeletal muscle regeneration by inducing inflammation via the TGF‐β signalling pathway. The findings of this study uncover a new potential target for skeletal muscle regeneration treatment.
Noncoding RNAs (ncRNAs) called tsRNAs (tRNA-derived short RNAs) have the ability to regulate gene expression. The information on tsRNAs in fat tissue is, however, limited. By sequencing, identifying, and analyzing tsRNAs using pigs as animal models, this research reports for the first time the characteristics of tsRNAs in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT). A total of 474 tsRNAs, 20 and 21 of which were particularly expressed in VAT and SAT, respectively, were found in WAT. According to the analysis of the tsRNA/miRNA/mRNA co-expression network, the tsRNAs with differential expression were primarily engaged in the endocrine and immune systems, which fall under the classification of organic systems, as well as the global and overview maps and lipid metropolis, which fall under the category of metabolism. This research also discovered a connection between the activity of the host tRNA engaged in translation and the production of tsRNAs. This research also discovered that tRF-Gly-GCC-037/tRF-Gly-GCC-042/tRF-Gly-CCC-016 and miR-218a/miR281b may be involved in the regulation of fatty acid metabolism in adipose tissue through SCD based on the tsRNA/miRNA/mRNA/fatty acid network. In conclusion, our findings enrich the understanding of ncRNAs in WAT metabolism and health regulation, as well as reveal the differences between SAT and VAT at the level of tsRNAs.
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