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This study investigated the effects of dietary Se levels on lipid metabolism and miRNA expression in the mesenteric adipose tissue of yellow catfish. Three experimental diets were formulated to contain 0.03 (low Se), 0.25 (adequate Se, control) and 6.39 mg Se/kg (high Se) for a 12-week trial. The enzymatic activities of lipogenesis, the expression levels of miRNA and its target gene related to lipid metabolism were detected. Compared with the control group, TG content increased significantly in the high-selenium group and low selenium group (P<0.05). Compared with the control group, the enzyme activities of G6PD and 6PGD decreased significantly in the low Se group (P<0.05), and significantly increased in the high Se group (P<0.05). Compared with the control group, the enzyme activity of ICDH decreased significantly in the high-Se group (P<0.05) with no significant change in the low-Se group; the enzyme activities of ME and FAS both increased significantly in the low and high Se groups (P<0.05); the expression levels of mir- 26a, mir-183, mir-135, let-7b, let-7c and let-7g in the high Se group increased significantly (P<0.05) with no significant difference in the low Se group. Though mir-181a-5p and let-7e increased significantly in the low-selenium group (P<0.05), it showed no significant difference in the high-selenium group. Selenium significantly increased mir-130 and mir-203a (P<0.05). Low selenium decreased significantly but high selenium increased the expressions of miR-200a, miR-143, let-7d and let-7f (P<0.05). MiR-143, miR-203a and miR-130 were highly expressed in adipose tissue, which were strongly responded to dietary Se levels. We used TargetScanFish6.2 and miRwalk3.0 to predict target genes of miR-130, miR-203a and miR-143, and performed KEGG enrichment analysis of target genes. The target genes of miR- 143 enriched significantly in mineral absorption, unsaturated fatty acid biosynthesis and insulin pathway (P<0.05, FDR≤ 0.05). The target genes of miR-203a was significantly enriched in lipid metabolic pathways and insulin signaling pathways (P<0.05, FDR≤0.05). The target genes of miR-130 enriched significantly in sphingolipid metabolism, lipid accumulation and mTOR signaling pathway (P<0.05, FDR≤0.05). Comprehensive analysis found that miR-130, miR-143 and miR-203a target genes were enriched in fatty acid synthesis signaling pathway, autophagy, apoptosis and insulin resistance. Then we selected target genes that both enriched in these signaling pathways for qPCR. The fas, cpt1a, hsl, srebp1, pparα and atgl mRNA expressions was consistent with miR-143, miR-203a and miR-130 expression levels. Therefore, we speculated that the dietary Se induced lipid metabolism via miR-143-, miR-203a- and miR-130-mediated expressions of fas, cpt1a, hsl, srebp1, pparα and atgl. [ABSTRACT FROM AUTHOR]

The present working hypothesis is that the Cu-induced changes in lipid metabolism may be mediated by miRNAs. Here, we describe the miRNA profile of the liver tissues of yellow catfish exposed to waterborne Cu, based on larger-scale sequencing of small RNA libraries. We identified a total of 172 distinct miRNAs. Among these miRNAs, compared to the control, mRNA expression levels of 16 miRNAs (miR-203a, 205, 1788-3p, 375, 31, 196a, 203b-3p, 2187-5p, 196d, 459-3p, 153a and miR-725, and two novel-miRNAs: chr4-1432, chr-7684) were down-regulated, and mRNA levels of miR-212 and chr20-5274 were up-regulated in Cu-exposed group. The functions of their target genes mainly involved ether lipid metabolism, glycerophospholipid metabolism, linoleic acid metabolism and α-linolenic acid metabolism. Cu exposure inhibited the expression of miR-205, whose predicted target genes were enriched in the pathway of lipid metabolism, including fas, lxrα, ddit3, lamp2, casp3a and baxa. These potential target genes were further verified by Dual-luciferase reporter gene assay. Using primary hepatocytes of yellow catfish, Cu incubation down-regulated miR-205 expression, and increased TG contents and FAS activity. LXR antagonist effectively ameliorate the Cu-induced change of TG content and FAS activity. These data suggest that down-regulation of the miRNA-205 may be an important step in Cu-induced changes in lipid metabolism in yellow catfish. [ABSTRACT FROM AUTHOR]

The goal of this study was to clone and characterize complete cDNA sequences of three important development-relevant genes of yellow catfish Pelteobagrus fulvidraco , including lrp6 , sox9a1 and fgfr2c , and explore their transcriptional responses in several tissues of P . fulvidraco to high fat diet. The predicted amino acid sequences of P . fulvidraco Lrp6, Sox9a1 and Fgfr2c contained all of the conserved structural features that were characteristic of these genes in other species, including YWTD domains, EGF-like repeats, LDLR ligand binding repeats, PPSP repeats motifs, HMG box, TA-binding functional domain, Ig I-III and PTK I-II. The mRNAs of the three genes were expressed in various tissues, but their mRNA levels varied among tissues. Compared to the control, high fat diet tended to down-regulate the mRNA expression of sox9a1 and fgfr2c in mesenteric fat, liver and ovary, and up-regulate their mRNA levels in muscle and kidney; in contrast, high fat diet down-regulated lrp6 mRNA levels in the ovary and muscle, but had no significant effects on lrp6 mRNA expression in mesenteric fat, liver and kidney. Our findings provide the first data about their expression responses to dietary lipid in teleosts and reinforce the multiple functions at the molecular level. [ABSTRACT FROM AUTHOR]