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There are 19 Wnt genes in mammals that belong to 12 subfamilies. Wnt signaling pathways participate in regulating numerous homeostatic and developmental processes in animals. However, the function of Wnt10b in fatty acid synthesis remains unclear in fish species. In the present study, we uncovered the role of the Wnt10b signaling pathway in the regulation of fatty acid synthesis in the muscle of zebrafish. The gene of Wnt10b was overexpressed in the muscle of zebrafish using pEGFP-N1-Wnt10b vector injection, which significantly decreased the expression of glycogen synthase kinase 3β (GSK-3β), but increased the expression of β-catenin, peroxisome proliferators-activated receptor γ (PPARγ), and CCAAT/enhancer binding protein α (C/EBPα). Moreover, the activity and mRNA expression of key lipogenic enzymes ATP-citrate lyase (ACL), acetyl-CoA carboxylase (ACC) and fatty acid synthetase (FAS), and the content of non-esterified fatty acids (NEFA), total cholesterol (TC), and triglyceride (TG) were also significantly decreased. Furthermore, interference of the Wnt10b gene significantly inhibited the expression of β-catenin, PPARγ, and C/EBPα, but significantly induced the expression of GSK-3β, FAS, ACC, and ACL. The content of NEFA, TC, and TG as well as the activity of FAS, ACC, and ACL significantly increased. Thus, our results showed that Wnt10b participates in regulating fatty acid synthesis via β-catenin, C/EBPα and PPARγ in the muscle of zebrafish. [ABSTRACT FROM AUTHOR]

In this study, the mechanism by which GSK-3β regulates protein synthesis and lipid deposition was investigated in zebrafish (Danio rerio). The vector of pEGFP-N1-GSK-3β was constructed and injected into the muscle of zebrafish. It was found that the mRNA and protein expression of tuberous sclerosis complex 2 (TSC2) was significantly increased. However, the mRNA and protein expression of mammalian target of rapamycin (mTOR), p70 ribosomal S6 kinase 1 (S6K1), and 4E-binding protein 1 (4EBP1) was significantly decreased by the pEGFP-N1-GSK-3β vector in the muscle of zebrafish. In addition, the mRNA and protein expression of β-catenin, CCAAT/enhancer binding protein α (C/EBPα), and peroxisome proliferators-activated receptor γ (PPARγ) was significantly decreased, but the mRNA expression of fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), ATP-citrate lyase (ACL), and HMG-CoA reductase (HMGCR) was significantly increased by the pEGFP-N1-GSK-3β vector. The activity of FAS, ACC, ACL, and HMGCR as well as the content of triglyceride (TG), total cholesterol (TC), and nonesterified fatty acids (NEFA) were significantly increased by the pEGFP-N1-GSK-3β vector in the muscle of zebrafish. The content of free amino acids Arg, Lys, His, Phe, Leu, Ile, Val, and Thr was significantly decreased by the pEGFP-N1-GSK-3β vector. The results indicate that GSK-3β may participate in regulating protein synthesis via TSC2/mTOR signaling and regulating lipid deposition via β-catenin in the muscle of zebrafish (Danio rerio). [ABSTRACT FROM AUTHOR]