MiRNA-mRNA integration analysis reveals the regulatory roles of miRNAs in the metabolism of largemouth bass (Micropterus salmoides) livers during acute hypoxic stress

Increasing culture density have elevated the probability of hypoxia occurring, which will inevitably lead to hypoxia stress of fish. In the present study, we simulated a hypoxic environment (1.2 ± 0.2 mg/L) that is likely to occur during aquaculture for 24 h, and conducted an integrated analysis of miRNA-mRNA using high-throughput sequencing to reveal the regulatory role of miRNAs in the metabolism of largemouth bass (Micropterus salmoides) livers during acute hypoxia exposure. Based on the pathways implicated by the differentially expressed mRNA and differentially expressed miRNAs' target genes, 7 processes related to carbohydrate and lipid metabolism were identified, namely pyruvate metabolism, the insulin signaling pathway, fatty acid degradation, fatty acid biosynthesis, glycolysis / gluconeogenesis, the PPAR (peroxisome proliferators-activated receptors) signaling pathway, and the VEGF (vascular endothelial growth factor) signaling pathway. There were 13 differentially expressed miRNAs involved in glucose and lipid metabolism, including miR-130a-3p, miR-2188-5p, miR-15b-5p, miR-96-5p, miR-27a-3p, mIR-152-3p, miR-133-3p, miR-101b-3p, miR-221-3p, miR-222a-3p, miR-153-3p, miR-200b-3p and miR-142a-3p. Their target genes were acsl4, aldh3a, irs, ehhadh, bad, mknk1, pik3cb, minnp1, cyp7a1, hk1, pgm, and crk, respectively. Specifically, miRNAs play an important role in regulating glycolysis and lipid mobilization in fish under hypoxic conditions. According to our current and previous research results, we can speculate that miRNAs play an important regulatory role in the transformation of metabolic patterns under hypoxic conditions, and this regulatory role may be conservative. These results will be helpful to understand the hypoxic response mechanisms in fish.