Abstract: Objective: To investigate the effects of increasing n-3 polyunsaturated fatty acids (n-3 PUFAs) on the body mass and the expression of exosomal miRNAs in the blood of mice, and to explore the antiobesity mechanism of n-3 through the exosomes. Methods: fat-1 transgenic mice were fed a high-fat diet (HFD) to create an obese animal model and the wild-type littermates served as the control group. The body masses of mice were measured, and exosomes from the plasma of mice were extracted and identified. RNA was isolated from the exosomes for high-throughput sequencing of miRNAs and construction of a library. According to the sequencing results, the target genes and related signaling pathways were explored by bioinformatics analysis, and the relationship between miRNAs and their target genes was also elucidated. Finally, the association of miRNAs with obesity and its roles in obesity were validated. Results: The body mass of fat-1 transgenic mice was significantly lower than that of their wild-type counterparts. The exosomes were successfully extracted and identified. High-throughput sequencing showed 46 significantly differentially expressed miRNAs (P < 0.05) with fold change (FC) value ≠ 1. Bioinformatics analysis revealed that six important miRNAs (mmu-miR-665-3p, mmu-miR-122-5p, mmu-miR-122-3p, mmu-miR-194-5p, mmu-miR-34c-5p, and mmu-miR-223-3p) were confirmed to play critical roles in fatty acid metabolism and endocytosis pathways, exerting functions related to lipid metabolism and obesity. Their target genes were Fads1, Elovl2, Elov6, Hadha, Scad1, Scad2, Hsd17b12, Acot2 and Acot4; and Arf6, H2-T-ps, Arrb1, Ist1, H2-T10, Wwp1, Snx4, IL2rb, Mvb12b, Rab11, fip3, Kif5a and Nedd4l in the two pathways, respectively. Conclusion: Increasing n-3 PUFAs can reduce body mass and alleviate obesity in mice. In addition, n-3 PUFAs can regulate the expression of miRNAs in blood exosomes; the significantly differentially expressed miRNAs are related to obesity, and their target genes are mainly involved in fatty acid metabolism pathways, suggesting that n-3 PUFAs may be involved in the molecular mechanism for inhibiting obesity.

Key words: n-3 polyunsaturated fatty acids; exosomes; miRNA; obesity; high-throughput sequencing