Limits...
Prenatal arsenic exposure alters gene expression in the adult liver to a proinflammatory state contributing to accelerated atherosclerosis.

States JC, Singh AV, Knudsen TB, Rouchka EC, Ngalame NO, Arteel GE, Piao Y, Ko MS - PLoS ONE (2012)

Bottom Line: Western blot analysis confirmed changes in the liver at PND70 that included increases of heat shock protein 70 (Hspa8) and active SREBP1.Plasma AST and ALT levels were increased at PND70.Genes containing SREBP1 binding sites also suggest pathways for diabetes mellitus and rheumatoid arthritis, both diseases that contribute to increased cardiovascular disease in humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky, United States of America. jcstates@louisville.edu

ABSTRACT
The mechanisms by which environmental toxicants alter developmental processes predisposing individuals to adult onset chronic disease are not well-understood. Transplacental arsenic exposure promotes atherogenesis in apolipoprotein E-knockout (ApoE(-/-)) mice. Because the liver plays a central role in atherosclerosis, diabetes and metabolic syndrome, we hypothesized that accelerated atherosclerosis may be linked to altered hepatic development. This hypothesis was tested in ApoE(-/-) mice exposed to 49 ppm arsenic in utero from gestational day (GD) 8 to term. GD18 hepatic arsenic was 1.2 µg/g in dams and 350 ng/g in fetuses. The hepatic transcriptome was evaluated by microarray analysis to assess mRNA and microRNA abundance in control and exposed pups at postnatal day (PND) 1 and PND70. Arsenic exposure altered postnatal developmental trajectory of mRNA and microRNA profiles. We identified an arsenic exposure related 51-gene signature at PND1 and PND70 with several hubs of interaction (Hspa8, IgM and Hnf4a). Gene ontology (GO) annotation analyses indicated that pathways for gluconeogenesis and glycolysis were suppressed in exposed pups at PND1, and pathways for protein export, ribosome, antigen processing and presentation, and complement and coagulation cascades were induced by PND70. Promoter analysis of differentially-expressed transcripts identified enriched transcription factor binding sites and clustering to common regulatory sites. SREBP1 binding sites were identified in about 16% of PND70 differentially-expressed genes. Western blot analysis confirmed changes in the liver at PND70 that included increases of heat shock protein 70 (Hspa8) and active SREBP1. Plasma AST and ALT levels were increased at PND70. These results suggest that transplacental arsenic exposure alters developmental programming in fetal liver, leading to an enduring stress and proinflammatory response postnatally that may contribute to early onset of atherosclerosis. Genes containing SREBP1 binding sites also suggest pathways for diabetes mellitus and rheumatoid arthritis, both diseases that contribute to increased cardiovascular disease in humans.

Show MeSH

Related in: MedlinePlus

HSP70 and SREBP1 expression in livers of 10 week old mice.A. Western blot analysis of HSP70 and SREBP1. The SREBP1 fragment shown is the 68 kDa cleavage fragment. B. Densitometric quantitation of western blots. Signals for each protein were normalized to GAPDH and mean of controls (#’s 1–4) was set = 1. Representative of triplicate blots shown. * = p<0.05.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3376138&req=5

pone-0038713-g006: HSP70 and SREBP1 expression in livers of 10 week old mice.A. Western blot analysis of HSP70 and SREBP1. The SREBP1 fragment shown is the 68 kDa cleavage fragment. B. Densitometric quantitation of western blots. Signals for each protein were normalized to GAPDH and mean of controls (#’s 1–4) was set = 1. Representative of triplicate blots shown. * = p<0.05.

Mentions: The mRNA expression data indicated that the genes for heat shock 70 proteins, HSP70 (HSPA1B, inducible form) and HSC70 (HSPA8, constitutive form), were induced. TFBS analyses indicated that SREBP1 binding sites were enriched in the promoters of differentially expressed genes in PND70 mice suggesting potential coordinate induction by SREBP1. However, SREBP1 mRNA level was unchanged. Because, SREBP1 activity is dependent upon cleavage in the endoplasmic reticulum, we examined expression of HSP70, HSC70 and the active form of SREBP1 by western blot analysis. The data (Figure 6) indicate that levels of HSP70 and activated SREBP1 are elevated in livers of As-exposed mice. Thus, the prediction made from the TFBS analysis, that activated SREBP1 is likely elevated because a battery of differentially expressed genes have an SREBP1 binding site in their promoters, is confirmed at the protein level. HSC70 did not change with arsenic exposure (not shown). The induction of HSP70 and activated SREBP1 in PND70 mice suggests a mild stress following prenatal arsenic exposure enduring into adult life. These results support the inferences made from the bioinformatics analyses of the mRNA microarray data.


Prenatal arsenic exposure alters gene expression in the adult liver to a proinflammatory state contributing to accelerated atherosclerosis.

States JC, Singh AV, Knudsen TB, Rouchka EC, Ngalame NO, Arteel GE, Piao Y, Ko MS - PLoS ONE (2012)

HSP70 and SREBP1 expression in livers of 10 week old mice.A. Western blot analysis of HSP70 and SREBP1. The SREBP1 fragment shown is the 68 kDa cleavage fragment. B. Densitometric quantitation of western blots. Signals for each protein were normalized to GAPDH and mean of controls (#’s 1–4) was set = 1. Representative of triplicate blots shown. * = p<0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3376138&req=5

pone-0038713-g006: HSP70 and SREBP1 expression in livers of 10 week old mice.A. Western blot analysis of HSP70 and SREBP1. The SREBP1 fragment shown is the 68 kDa cleavage fragment. B. Densitometric quantitation of western blots. Signals for each protein were normalized to GAPDH and mean of controls (#’s 1–4) was set = 1. Representative of triplicate blots shown. * = p<0.05.
Mentions: The mRNA expression data indicated that the genes for heat shock 70 proteins, HSP70 (HSPA1B, inducible form) and HSC70 (HSPA8, constitutive form), were induced. TFBS analyses indicated that SREBP1 binding sites were enriched in the promoters of differentially expressed genes in PND70 mice suggesting potential coordinate induction by SREBP1. However, SREBP1 mRNA level was unchanged. Because, SREBP1 activity is dependent upon cleavage in the endoplasmic reticulum, we examined expression of HSP70, HSC70 and the active form of SREBP1 by western blot analysis. The data (Figure 6) indicate that levels of HSP70 and activated SREBP1 are elevated in livers of As-exposed mice. Thus, the prediction made from the TFBS analysis, that activated SREBP1 is likely elevated because a battery of differentially expressed genes have an SREBP1 binding site in their promoters, is confirmed at the protein level. HSC70 did not change with arsenic exposure (not shown). The induction of HSP70 and activated SREBP1 in PND70 mice suggests a mild stress following prenatal arsenic exposure enduring into adult life. These results support the inferences made from the bioinformatics analyses of the mRNA microarray data.

Bottom Line: Western blot analysis confirmed changes in the liver at PND70 that included increases of heat shock protein 70 (Hspa8) and active SREBP1.Plasma AST and ALT levels were increased at PND70.Genes containing SREBP1 binding sites also suggest pathways for diabetes mellitus and rheumatoid arthritis, both diseases that contribute to increased cardiovascular disease in humans.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky, United States of America. jcstates@louisville.edu

ABSTRACT
The mechanisms by which environmental toxicants alter developmental processes predisposing individuals to adult onset chronic disease are not well-understood. Transplacental arsenic exposure promotes atherogenesis in apolipoprotein E-knockout (ApoE(-/-)) mice. Because the liver plays a central role in atherosclerosis, diabetes and metabolic syndrome, we hypothesized that accelerated atherosclerosis may be linked to altered hepatic development. This hypothesis was tested in ApoE(-/-) mice exposed to 49 ppm arsenic in utero from gestational day (GD) 8 to term. GD18 hepatic arsenic was 1.2 µg/g in dams and 350 ng/g in fetuses. The hepatic transcriptome was evaluated by microarray analysis to assess mRNA and microRNA abundance in control and exposed pups at postnatal day (PND) 1 and PND70. Arsenic exposure altered postnatal developmental trajectory of mRNA and microRNA profiles. We identified an arsenic exposure related 51-gene signature at PND1 and PND70 with several hubs of interaction (Hspa8, IgM and Hnf4a). Gene ontology (GO) annotation analyses indicated that pathways for gluconeogenesis and glycolysis were suppressed in exposed pups at PND1, and pathways for protein export, ribosome, antigen processing and presentation, and complement and coagulation cascades were induced by PND70. Promoter analysis of differentially-expressed transcripts identified enriched transcription factor binding sites and clustering to common regulatory sites. SREBP1 binding sites were identified in about 16% of PND70 differentially-expressed genes. Western blot analysis confirmed changes in the liver at PND70 that included increases of heat shock protein 70 (Hspa8) and active SREBP1. Plasma AST and ALT levels were increased at PND70. These results suggest that transplacental arsenic exposure alters developmental programming in fetal liver, leading to an enduring stress and proinflammatory response postnatally that may contribute to early onset of atherosclerosis. Genes containing SREBP1 binding sites also suggest pathways for diabetes mellitus and rheumatoid arthritis, both diseases that contribute to increased cardiovascular disease in humans.

Show MeSH
Related in: MedlinePlus