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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.

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Related in: MedlinePlus

Identification and analyses of 51 genes differentially expressed at both PND1 and PND70.A. Intersection of genes differentially expressed at PND1 and PND70. B. Hierarchical clustering of 51 genes differentially expressed at both PND 1 and PND70. C. Principal component analysis of 51 genes differentially expressed at both PND 1 and PND70. (Arrows added for clarity) D. Pathway Architect analysis of 51 genes differentially expressed at both PND 1 and PND70.
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pone-0038713-g003: Identification and analyses of 51 genes differentially expressed at both PND1 and PND70.A. Intersection of genes differentially expressed at PND1 and PND70. B. Hierarchical clustering of 51 genes differentially expressed at both PND 1 and PND70. C. Principal component analysis of 51 genes differentially expressed at both PND 1 and PND70. (Arrows added for clarity) D. Pathway Architect analysis of 51 genes differentially expressed at both PND 1 and PND70.

Mentions: The expression of most genes in a pathway changes little when a pathway is induced because only a few are actually rate limiting. However, in order to identify an affected pathway in biological function analyses, one must have a sufficient number of genes differentially expressed to detect an enriched pathway. In addition, we were analyzing total liver RNA and liver is composed of multiple cell types, each making their contribution to the total RNA pool. Our plan included confirmation of conclusions from genomics analyses with biochemical or biological assays post-hoc. Hence, we sought to identify all genes with changed expression and set the criteria accordingly. Total RNAs were prepared from liver samples from pups prenatally exposed to arsenic and evaluated on day of birth (PND1) and 10-weeks of age (PND70) (n = 3 for each group). The experimental design and workflow for the RNA analyses is shown in Figure 2. RNAs were prepared and analyzed by microarrays as described in methods. We identified a total 848 probes mapping to 797 individual genes with expression changed by in utero arsenic exposure at PND1 and 763 probes mapping to 712 individual genes at PND70 (p<0.01, any change; Figure 3A).


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)

Identification and analyses of 51 genes differentially expressed at both PND1 and PND70.A. Intersection of genes differentially expressed at PND1 and PND70. B. Hierarchical clustering of 51 genes differentially expressed at both PND 1 and PND70. C. Principal component analysis of 51 genes differentially expressed at both PND 1 and PND70. (Arrows added for clarity) D. Pathway Architect analysis of 51 genes differentially expressed at both PND 1 and PND70.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0038713-g003: Identification and analyses of 51 genes differentially expressed at both PND1 and PND70.A. Intersection of genes differentially expressed at PND1 and PND70. B. Hierarchical clustering of 51 genes differentially expressed at both PND 1 and PND70. C. Principal component analysis of 51 genes differentially expressed at both PND 1 and PND70. (Arrows added for clarity) D. Pathway Architect analysis of 51 genes differentially expressed at both PND 1 and PND70.
Mentions: The expression of most genes in a pathway changes little when a pathway is induced because only a few are actually rate limiting. However, in order to identify an affected pathway in biological function analyses, one must have a sufficient number of genes differentially expressed to detect an enriched pathway. In addition, we were analyzing total liver RNA and liver is composed of multiple cell types, each making their contribution to the total RNA pool. Our plan included confirmation of conclusions from genomics analyses with biochemical or biological assays post-hoc. Hence, we sought to identify all genes with changed expression and set the criteria accordingly. Total RNAs were prepared from liver samples from pups prenatally exposed to arsenic and evaluated on day of birth (PND1) and 10-weeks of age (PND70) (n = 3 for each group). The experimental design and workflow for the RNA analyses is shown in Figure 2. RNAs were prepared and analyzed by microarrays as described in methods. We identified a total 848 probes mapping to 797 individual genes with expression changed by in utero arsenic exposure at PND1 and 763 probes mapping to 712 individual genes at PND70 (p<0.01, any change; Figure 3A).

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