Peroxisome proliferator-activated receptor gamma (PPARγ) in yellow catfish Pelteobagrus fulvidraco: Molecular characterization, mRNA expression and transcriptional regulation by insulin in vivo and in vitro

Zheng, Jia; Zhuo, Mei-Qin; Luo, Zhi; Pan, Ya–Xiong; Song, Yong; Huang, Chao; Zhu, Qing–Ling; Hu, Wei; Chen, Qiliang

doi:10.1016/j.ygcen.2014.12.020

Cited by 25 publications

(15 citation statements)

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“…PPARγ is critical for the regulation of lipogenesis and lipid storage, and PPARα has been implicated in fatty acid catabolism (Ribet et al, 2010;Minghetti et al, 2011). The findings of the present study indicate that insulin injection significantly influences mRNA levels of PPARα and PPARγ, suggesting that they mediate the insulin-induced change of lipid metabolism, in agreement with other studies (Zhuo et al, 2014;Cruz-Garcia et al, 2015;Zheng et al, 2015b). However, we also found some differences between our in vivo study and the in vitro study (Zhuo et al, 2014) in the insulin-induced change in mRNA levels of these transcription factors.…”

Section: Discussionsupporting

confidence: 91%

“…In contrast, the phosphatidylinositol 3-kinase (PI3K) pathway is the main pathway involved in the metabolic actions of insulin (Shepherd et al, 1995(Shepherd et al, , 1998Catalucci et al, 2009), and inhibition of the PI3K pathway by wortmannin blocks most metabolic actions of insulin (Saltiel and Kahn, 2001;Okada et al, 1994). Recently, in our laboratory, studies have suggested that bovine insulin incubation significantly influences the mRNA expression of PPARγ and PPARα in yellow catfish (Zhuo et al, 2014;Zheng et al, 2015b). However, in fish, detailed information of the effects of these signaling pathways (PPARα, PPARγ and PI3K) on the action of insulin on lipid metabolism remains unknown.…”

Section: Introductionmentioning

confidence: 99%

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Effect and the related signaling pathways of insulin influencing lipid metabolism in yellow catfishPelteobagrus fulvidraco

Zhuo

Luo

Pan

et al. 2015

Journal of Experimental Biology

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The influence of insulin on hepatic metabolism in fish is not well understood. The present study was therefore conducted to investigate the effects of insulin on lipid metabolism, and the related signaling pathways, in the yellow catfish Pelteobagrus fulvidraco. Hepatic lipid and intracellular triglyceride (TG) content, the activity and expression levels of several enzymes and the mRNA expression of transcription factors (PPARα and PPARγ) involved in lipid metabolism were determined. Troglitazone, GW6471, fenofibrate and wortmannin were used to explore the signaling pathways by which insulin influences lipid metabolism. Insulin tended to increase hepatic lipid accumulation, the activity of lipogenic enzymes (6PGD, G6PD, ME, ICDH and FAS) and mRNA levels of FAS, G6PD, 6PGD, CPT IA and PPARγ, but down-regulated PPARα mRNA level. The insulin-induced effect could be stimulated by the specific PPARγ activator troglitazone or reversed by the PI3 kinase/Akt inhibitor wortmannin, demonstrating that signaling pathways of PPARγ and PI3 kinase/Akt were involved in the insulin-induced alteration of lipid metabolism. The specific PPARα pathway activator fenofibrate reduced insulininduced TG accumulation, down-regulated the mRNA levels of FAS, G6PD and 6PGD, and up-regulated mRNA levels of CPT IA, PPARα and PPARγ. The specific PPARα pathway inhibitor GW6471 reduced insulin-induced changes in the expression of all the tested genes, indicating that PPARα mediated the insulin-induced changes of lipid metabolism. The present results contribute new knowledge on the regulatory role of insulin in hepatic metabolism in fish.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Effect and the related signaling pathways of insulin influencing lipid metabolism in yellow catfishPelteobagrus fulvidraco

Zhuo

Luo

Pan

et al. 2015

Journal of Experimental Biology

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“…A lthough the overall primary sequence of lhPPARγ shows 64.8% identity with human PPA Rγ, the DBD and LBD show 95.2% and 72.2% identit ies, respectively. Similar results were also found in many other studies (Boukouvala et al, 2004, Cho et al, 2009Luo et al, 2015;Zheng et al, 2015) indicating that the DBD and LBD of these receptors were conserved in the lower vertebrates. Multiple sequence alignment demonstrated that the fish PPA Rγ p rotein is appro ximately 30 amino acid residues longer than its mammalian counterpart mainly inserting in N-terminal and LBD.…”

supporting

confidence: 90%

“…The highest mRNA level of lhPPARγ observed in abdomen fat was in agreement with its physiological role in fat accu mu lation and adipocyte differentiat ion (Rosen & Spiegelman, 2006). Similar findings were also observed in other fish such as yellow catfish (Zheng et al, 2015), orange-spotted grouper and olive flounder (Cho et al, 2009). In contrast, the highest PPARγ mRNA expression level was observed in liver and intestine in adult and immature Megalobrama amblycephala, respectively (Li, Gu i, Wang, Qian, & Zhao, 2013).…”

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confidence: 86%

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Wang¹,

Yang²,

Liu³

et al. 2017

Turk. J. Fish. Aquat. Sci.

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Redlip mullet (Liza haematocheila) PPARγ cDNA (lhPPARγ) by reverse transcription polymerase chain reaction (RT -PCR) and rapid amplification of cDNA ends (RACE) were isolated in this study. The full-length cDNA was 2985 bp, consisted of a 200 bp 5'UTR, 1183 bp 3'UTR and 1599 bp ORF encoding a polypeptide with 533 amino acids. lhPPARγ protein was predicted to consist of four domains, i.e. N-terminal domain, DNA-binding domain, C-terminal ligand binding domain and flexible hinge domain. Real time quantitative RT-PCR revealed that lhPPARγ mRNA was detected in all tested tissues. The highest expression level of lhPPARγ mRNA was observed in abdomen fat followed by intestine, gill, kidney, liver, skin, brain, spleen, stomach, liver, heart and muscle. These results suggested that lhPPARγ was functionally and evolutionarily conserved between redlip mullet and other vertebrates. Six iso-nitrogenous diets with different lipid level (from 2.0% to 14.6%) were fed to triplicate groups. Although fish fed diets containing 14.6% lipid showed higher lhPPARγ mRNA expression in the liver, intestine and muscle than fish fed other diets, no significant difference was observed, which indicated redlip mullet might adapt to high lipid level below 14.6%.

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“…Further investigation indicated that PPARα stimulated through a peroxisome proliferator-responsive element (PPRE) in the first and second intron of the human and rat CPT Iα genes, respectively [ 27 , 28 ]. PPARγ, involved in the regulation of lipogenesis and lipid storage, preferentially control the transcription of genes in triglyceride synthesis [ 29 ]. In an earlier study, Chen et al [ 30 ] found that mRNA expression of PPARγ was positively correlated with CPT I expression, suggesting a potential regulation of PPARγ on CPT I expression.…”

Section: Introductionmentioning

confidence: 99%

Structure and Functional Analysis of Promoters from Two Liver Isoforms of CPT I in Grass Carp Ctenopharyngodon idella

Luo

et al. 2017

IJMS

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Carnitine palmitoyltransferase I (CPT I) is a key enzyme involved in the regulation of lipid metabolism and fatty acid β-oxidation. To understand the transcriptional mechanism of CPT Iα1b and CPT Iα2a genes, we cloned the 2695-bp and 2631-bp regions of CPT Iα1b and CPT Iα2a promoters of grass carp (Ctenopharyngodon idella), respectively, and explored the structure and functional characteristics of these promoters. CPT Iα1b had two transcription start sites (TSSs), while CPT Iα2a had only one TSS. DNase I foot printing showed that the CPT Iα1b promoter was AT-rich and TATA-less, and mediated basal transcription through an initiator (INR)-independent mechanism. Bioinformatics analysis indicated that specificity protein 1 (Sp1) and nuclear factor Y (NF-Y) played potential important roles in driving basal expression of CPT Iα2a gene. In HepG2 and HEK293 cells, progressive deletion analysis indicated that several regions contained cis-elements controlling the transcription of the CPT Iα1b and CPT Iα2a genes. Moreover, some transcription factors, such as thyroid hormone receptor (TR), hepatocyte nuclear factor 4 (HNF4) and peroxisome proliferator-activated receptor (PPAR) family, were all identified on the CPT Iα1b and CPT Iα2a promoters. The TRα binding sites were only identified on CPT Iα1b promoter, while TRβ binding sites were only identified on CPT Iα2a promoter, suggesting that the transcription of CPT Iα1b and CPT Iα2a was regulated by a different mechanism. Site-mutation and electrophoretic mobility-shift assay (EMSA) revealed that fenofibrate-induced PPARα activation did not bind with predicted PPARα binding sites of CPT I promoters. Additionally, PPARα was not the only member of PPAR family regulating CPT I expression, and PPARγ also regulated the CPT I expression. All of these results provided new insights into the mechanisms for transcriptional regulation of CPT I genes in fish.

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Peroxisome proliferator-activated receptor gamma (PPARγ) in yellow catfish Pelteobagrus fulvidraco: Molecular characterization, mRNA expression and transcriptional regulation by insulin in vivo and in vitro

Cited by 25 publications

References 55 publications

Effect and the related signaling pathways of insulin influencing lipid metabolism in yellow catfishPelteobagrus fulvidraco

Effect and the related signaling pathways of insulin influencing lipid metabolism in yellow catfishPelteobagrus fulvidraco

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Structure and Functional Analysis of Promoters from Two Liver Isoforms of CPT I in Grass Carp Ctenopharyngodon idella

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