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Znf202 affects high density lipoprotein cholesterol levels and promotes hepatosteatosis in hyperlipidemic mice.

Vrins CL, Out R, van Santbrink P, van der Zee A, Mahmoudi T, Groenendijk M, Havekes LM, van Berkel TJ, Willems van Dijk K, Biessen EA - PLoS ONE (2013)

Bottom Line: The repressive activity of Znf202 was firmly confirmed in an apoE reporter assay and Znf202 responsive elements within the ApoE promoter were identified.Interestingly, key genes in bile flux (abcg5/8 and bsep) and in bile acid synthesis (cyp7a1) were also downregulated.Znf202 overexpression in vivo reveals an important role of this transcriptional regulator in liver lipid homeostasis, while firmly establishing the proposed key role in the control of HDL levels.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Biochemistry, Academic Medical Center, Amsterdam, The Netherlands. c_vrins@hotmail.com

ABSTRACT

Background: The zinc finger protein Znf202 is a transcriptional suppressor of lipid related genes and has been linked to hypoalphalipoproteinemia. A functional role of Znf202 in lipid metabolism in vivo still remains to be established.

Methodology and principal findings: We generated mouse Znf202 expression vectors, the functionality of which was established in several in vitro systems. Next, effects of adenoviral znf202 overexpression in vivo were determined in normo- as well as hyperlipidemic mouse models. Znf202 overexpression in mouse hepatoma cells mhAT3F2 resulted in downregulation of members of the Apoe/c1/c2 and Apoa1/c3/a4 gene cluster. The repressive activity of Znf202 was firmly confirmed in an apoE reporter assay and Znf202 responsive elements within the ApoE promoter were identified. Adenoviral Znf202 transfer to Ldlr-/- mice resulted in downregulation of apoe, apoc1, apoa1, and apoc3 within 24 h after gene transfer. Interestingly, key genes in bile flux (abcg5/8 and bsep) and in bile acid synthesis (cyp7a1) were also downregulated. At 5 days post-infection, the expression of the aforementioned genes was normalized, but mice had developed severe hepatosteatosis accompanied by hypercholesterolemia and hypoalphalipoproteinemia. A much milder phenotype was observed in wildtype mice after 5 days of hepatic Znf202 overexpression. Interestingly and similar to Ldl-/- mice, HDL-cholesterol levels in wildtype mice were lowered after hepatic Znf202 overexpression.

Conclusion/significance: Znf202 overexpression in vivo reveals an important role of this transcriptional regulator in liver lipid homeostasis, while firmly establishing the proposed key role in the control of HDL levels.

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Related in: MedlinePlus

Hepatic Znf202 overexpression causes hepatosteatosis in Ldlr−/− mice only.Livers were isolated from Ldlr−/− and WT mice 5 days after injection with 2.109 pfu of Ad.Znf202 (filled bars) or Ad-mock (empty bars). Cryosections were prepared from Ldlr−/− liver samples and stained with Oil Red-O (A). Hepatic lipids were extracted from homogenized liver samples and cholesterol and TG concentrations were determined (B). Values are expressed as µg lipid per mg tissue protein and are means ± SD (n = 4). * indicates p<0.05.
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pone-0057492-g004: Hepatic Znf202 overexpression causes hepatosteatosis in Ldlr−/− mice only.Livers were isolated from Ldlr−/− and WT mice 5 days after injection with 2.109 pfu of Ad.Znf202 (filled bars) or Ad-mock (empty bars). Cryosections were prepared from Ldlr−/− liver samples and stained with Oil Red-O (A). Hepatic lipids were extracted from homogenized liver samples and cholesterol and TG concentrations were determined (B). Values are expressed as µg lipid per mg tissue protein and are means ± SD (n = 4). * indicates p<0.05.

Mentions: Histological analysis of livers isolated from Ad.Znf202 and Ad.Mock treated Ldlr−/− and WT mice at day 5 post transduction revealed some striking differences. In Ldlr−/− mice, Znf202 overexpressing livers were characterized by massive oil-red-O stained lipid deposition in intracellular vacuoles mainly (Fig. 4A), while liver morphology of Znf202 transduced WT mice was normal (data not shown). As liver morphology of Ad.Znf202 treated mice was highly reminiscent of steatosis, we assayed the liver lipid content quantitatively. As can be appreciated from figure 4B, Znf202 overexpressing livers from Ldlr−/− mice contained over 2-fold higher TC, cholesteryl esters (CE), and TG. In line with their normal liver morphology, no changes in hepatic lipid content were observed in Znf202 transduced WT mice.


Znf202 affects high density lipoprotein cholesterol levels and promotes hepatosteatosis in hyperlipidemic mice.

Vrins CL, Out R, van Santbrink P, van der Zee A, Mahmoudi T, Groenendijk M, Havekes LM, van Berkel TJ, Willems van Dijk K, Biessen EA - PLoS ONE (2013)

Hepatic Znf202 overexpression causes hepatosteatosis in Ldlr−/− mice only.Livers were isolated from Ldlr−/− and WT mice 5 days after injection with 2.109 pfu of Ad.Znf202 (filled bars) or Ad-mock (empty bars). Cryosections were prepared from Ldlr−/− liver samples and stained with Oil Red-O (A). Hepatic lipids were extracted from homogenized liver samples and cholesterol and TG concentrations were determined (B). Values are expressed as µg lipid per mg tissue protein and are means ± SD (n = 4). * indicates p<0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585336&req=5

pone-0057492-g004: Hepatic Znf202 overexpression causes hepatosteatosis in Ldlr−/− mice only.Livers were isolated from Ldlr−/− and WT mice 5 days after injection with 2.109 pfu of Ad.Znf202 (filled bars) or Ad-mock (empty bars). Cryosections were prepared from Ldlr−/− liver samples and stained with Oil Red-O (A). Hepatic lipids were extracted from homogenized liver samples and cholesterol and TG concentrations were determined (B). Values are expressed as µg lipid per mg tissue protein and are means ± SD (n = 4). * indicates p<0.05.
Mentions: Histological analysis of livers isolated from Ad.Znf202 and Ad.Mock treated Ldlr−/− and WT mice at day 5 post transduction revealed some striking differences. In Ldlr−/− mice, Znf202 overexpressing livers were characterized by massive oil-red-O stained lipid deposition in intracellular vacuoles mainly (Fig. 4A), while liver morphology of Znf202 transduced WT mice was normal (data not shown). As liver morphology of Ad.Znf202 treated mice was highly reminiscent of steatosis, we assayed the liver lipid content quantitatively. As can be appreciated from figure 4B, Znf202 overexpressing livers from Ldlr−/− mice contained over 2-fold higher TC, cholesteryl esters (CE), and TG. In line with their normal liver morphology, no changes in hepatic lipid content were observed in Znf202 transduced WT mice.

Bottom Line: The repressive activity of Znf202 was firmly confirmed in an apoE reporter assay and Znf202 responsive elements within the ApoE promoter were identified.Interestingly, key genes in bile flux (abcg5/8 and bsep) and in bile acid synthesis (cyp7a1) were also downregulated.Znf202 overexpression in vivo reveals an important role of this transcriptional regulator in liver lipid homeostasis, while firmly establishing the proposed key role in the control of HDL levels.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Biochemistry, Academic Medical Center, Amsterdam, The Netherlands. c_vrins@hotmail.com

ABSTRACT

Background: The zinc finger protein Znf202 is a transcriptional suppressor of lipid related genes and has been linked to hypoalphalipoproteinemia. A functional role of Znf202 in lipid metabolism in vivo still remains to be established.

Methodology and principal findings: We generated mouse Znf202 expression vectors, the functionality of which was established in several in vitro systems. Next, effects of adenoviral znf202 overexpression in vivo were determined in normo- as well as hyperlipidemic mouse models. Znf202 overexpression in mouse hepatoma cells mhAT3F2 resulted in downregulation of members of the Apoe/c1/c2 and Apoa1/c3/a4 gene cluster. The repressive activity of Znf202 was firmly confirmed in an apoE reporter assay and Znf202 responsive elements within the ApoE promoter were identified. Adenoviral Znf202 transfer to Ldlr-/- mice resulted in downregulation of apoe, apoc1, apoa1, and apoc3 within 24 h after gene transfer. Interestingly, key genes in bile flux (abcg5/8 and bsep) and in bile acid synthesis (cyp7a1) were also downregulated. At 5 days post-infection, the expression of the aforementioned genes was normalized, but mice had developed severe hepatosteatosis accompanied by hypercholesterolemia and hypoalphalipoproteinemia. A much milder phenotype was observed in wildtype mice after 5 days of hepatic Znf202 overexpression. Interestingly and similar to Ldl-/- mice, HDL-cholesterol levels in wildtype mice were lowered after hepatic Znf202 overexpression.

Conclusion/significance: Znf202 overexpression in vivo reveals an important role of this transcriptional regulator in liver lipid homeostasis, while firmly establishing the proposed key role in the control of HDL levels.

Show MeSH
Related in: MedlinePlus