Limits...
Epigenetic alterations in liver of C57BL/6J mice after short-term inhalational exposure to 1,3-butadiene.

Koturbash I, Scherhag A, Sorrentino J, Sexton K, Bodnar W, Tryndyak V, Latendresse JR, Swenberg JA, Beland FA, Pogribny IP, Rusyn I - Environ. Health Perspect. (2010)

Bottom Line: We detected N-7-(2,3,4-trihydroxybut-1-yl)guanine (THB-Gua) adducts in liver DNA of exposed mice in a dose-responsive manner, and also observed extensive alterations in the cellular epigenome in the liver, including demethylation of global DNA and repetitive elements and a decrease in histone H3 and H4 lysine methylation.In addition, we observed down-regulation of DNA methyltransferase 1 (Dnmt1) and suppressor of variegation 3-9 homolog 1, a histone lysine methyltransferase (Suv39h1), and up-regulation of the histone demethylase Jumonji domain 2 (Jmjd2a), proteins responsible for the accurate maintenance of the epigenetic marks.This study demonstrates that exposure to BD leads to epigenetic alterations in the liver, which may be important contributors to the mode of BD carcinogenicity.

View Article: PubMed Central - PubMed

Affiliation: Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA.

ABSTRACT

Background: 1,3-Butadiene (BD) is a high-volume industrial chemical and a known human carcinogen. The main mode of BD carcinogenicity is thought to involve formation of genotoxic epoxides.

Objectives: In this study we tested the hypothesis that BD may be epigenotoxic (i.e., cause changes in DNA and histone methylation) and explored the possible molecular mechanisms for the epigenetic changes.

Methods and results: We administered BD (6.25 and 625 ppm) to C57BL/6J male mice by inhalation for 2 weeks (6 hr/day, 5 days a week) and then examined liver tissue from these mice for signs of toxicity using histopathology and gene expression analyses. We observed no changes in mice exposed to 6.25 ppm BD, but glycogen depletion and dysregulation of hepatotoxicity biomarker genes were observed in mice exposed to 625 ppm BD. We detected N-7-(2,3,4-trihydroxybut-1-yl)guanine (THB-Gua) adducts in liver DNA of exposed mice in a dose-responsive manner, and also observed extensive alterations in the cellular epigenome in the liver, including demethylation of global DNA and repetitive elements and a decrease in histone H3 and H4 lysine methylation. In addition, we observed down-regulation of DNA methyltransferase 1 (Dnmt1) and suppressor of variegation 3-9 homolog 1, a histone lysine methyltransferase (Suv39h1), and up-regulation of the histone demethylase Jumonji domain 2 (Jmjd2a), proteins responsible for the accurate maintenance of the epigenetic marks. Although the epigenetic effects were most pronounced in the 625-ppm exposure group, some effects were evident in mice exposed to 6.25 ppm BD.

Conclusions: This study demonstrates that exposure to BD leads to epigenetic alterations in the liver, which may be important contributors to the mode of BD carcinogenicity.

Show MeSH

Related in: MedlinePlus

Effects of BD exposure on histone trimethylation in mouse liver as determined by Western blotting. (A) H3K9me3, H3K27me3, and H4K20me3 levels assessed by immunostaining using specific antibodies against trimethylated histones; equal sample loading was confirmed by immunostaining against histone H3 (“Loading” row) and histone H4 (data not shown). (B) Densitometry analysis of the immunostaining results shown as change in methylation relative to control after correction for the total amount of each histone in the individual samples; data are presented as mean ± SD (n = 5).*p < 0.05 compared with control.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3094413&req=5

f3-ehp-119-635: Effects of BD exposure on histone trimethylation in mouse liver as determined by Western blotting. (A) H3K9me3, H3K27me3, and H4K20me3 levels assessed by immunostaining using specific antibodies against trimethylated histones; equal sample loading was confirmed by immunostaining against histone H3 (“Loading” row) and histone H4 (data not shown). (B) Densitometry analysis of the immunostaining results shown as change in methylation relative to control after correction for the total amount of each histone in the individual samples; data are presented as mean ± SD (n = 5).*p < 0.05 compared with control.

Mentions: Alterations in histone-controlled chromatin structure are important epigenetic changes elicited by many toxicants (Bagnyukova et al. 2008; Moggs and Orphanides 2004); therefore, we examined the effect of BD on the extent of methylation of histones H3K9, H3K27, and H4K20. We found no changes in histone trimethylation in the livers of mice exposed to 6.25 ppm BD (Figure 3). In contrast, exposure to 625 ppm BD caused a significant decrease in the levels of H3K9me3, H3K27me3, and H4K20me3: 30%, 19%, and 54% lower, respectively, than in control mice. Exposure to either 6.25 or 625 ppm BD had no effect on the extent of histone H3K9 monomethylation (H3K9me1) or dimethylation (H3K9me2) or H4K20 monomethylation (H4K20me1 [see Supplemental Material, Figure 2 (doi:10.1289/ehp.1002910)]. H4K20me2 was decreased by 39% in mice exposed to 625 ppm BD (see Supplemental Material, Figure 2).


Epigenetic alterations in liver of C57BL/6J mice after short-term inhalational exposure to 1,3-butadiene.

Koturbash I, Scherhag A, Sorrentino J, Sexton K, Bodnar W, Tryndyak V, Latendresse JR, Swenberg JA, Beland FA, Pogribny IP, Rusyn I - Environ. Health Perspect. (2010)

Effects of BD exposure on histone trimethylation in mouse liver as determined by Western blotting. (A) H3K9me3, H3K27me3, and H4K20me3 levels assessed by immunostaining using specific antibodies against trimethylated histones; equal sample loading was confirmed by immunostaining against histone H3 (“Loading” row) and histone H4 (data not shown). (B) Densitometry analysis of the immunostaining results shown as change in methylation relative to control after correction for the total amount of each histone in the individual samples; data are presented as mean ± SD (n = 5).*p < 0.05 compared with control.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3094413&req=5

f3-ehp-119-635: Effects of BD exposure on histone trimethylation in mouse liver as determined by Western blotting. (A) H3K9me3, H3K27me3, and H4K20me3 levels assessed by immunostaining using specific antibodies against trimethylated histones; equal sample loading was confirmed by immunostaining against histone H3 (“Loading” row) and histone H4 (data not shown). (B) Densitometry analysis of the immunostaining results shown as change in methylation relative to control after correction for the total amount of each histone in the individual samples; data are presented as mean ± SD (n = 5).*p < 0.05 compared with control.
Mentions: Alterations in histone-controlled chromatin structure are important epigenetic changes elicited by many toxicants (Bagnyukova et al. 2008; Moggs and Orphanides 2004); therefore, we examined the effect of BD on the extent of methylation of histones H3K9, H3K27, and H4K20. We found no changes in histone trimethylation in the livers of mice exposed to 6.25 ppm BD (Figure 3). In contrast, exposure to 625 ppm BD caused a significant decrease in the levels of H3K9me3, H3K27me3, and H4K20me3: 30%, 19%, and 54% lower, respectively, than in control mice. Exposure to either 6.25 or 625 ppm BD had no effect on the extent of histone H3K9 monomethylation (H3K9me1) or dimethylation (H3K9me2) or H4K20 monomethylation (H4K20me1 [see Supplemental Material, Figure 2 (doi:10.1289/ehp.1002910)]. H4K20me2 was decreased by 39% in mice exposed to 625 ppm BD (see Supplemental Material, Figure 2).

Bottom Line: We detected N-7-(2,3,4-trihydroxybut-1-yl)guanine (THB-Gua) adducts in liver DNA of exposed mice in a dose-responsive manner, and also observed extensive alterations in the cellular epigenome in the liver, including demethylation of global DNA and repetitive elements and a decrease in histone H3 and H4 lysine methylation.In addition, we observed down-regulation of DNA methyltransferase 1 (Dnmt1) and suppressor of variegation 3-9 homolog 1, a histone lysine methyltransferase (Suv39h1), and up-regulation of the histone demethylase Jumonji domain 2 (Jmjd2a), proteins responsible for the accurate maintenance of the epigenetic marks.This study demonstrates that exposure to BD leads to epigenetic alterations in the liver, which may be important contributors to the mode of BD carcinogenicity.

View Article: PubMed Central - PubMed

Affiliation: Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas, USA.

ABSTRACT

Background: 1,3-Butadiene (BD) is a high-volume industrial chemical and a known human carcinogen. The main mode of BD carcinogenicity is thought to involve formation of genotoxic epoxides.

Objectives: In this study we tested the hypothesis that BD may be epigenotoxic (i.e., cause changes in DNA and histone methylation) and explored the possible molecular mechanisms for the epigenetic changes.

Methods and results: We administered BD (6.25 and 625 ppm) to C57BL/6J male mice by inhalation for 2 weeks (6 hr/day, 5 days a week) and then examined liver tissue from these mice for signs of toxicity using histopathology and gene expression analyses. We observed no changes in mice exposed to 6.25 ppm BD, but glycogen depletion and dysregulation of hepatotoxicity biomarker genes were observed in mice exposed to 625 ppm BD. We detected N-7-(2,3,4-trihydroxybut-1-yl)guanine (THB-Gua) adducts in liver DNA of exposed mice in a dose-responsive manner, and also observed extensive alterations in the cellular epigenome in the liver, including demethylation of global DNA and repetitive elements and a decrease in histone H3 and H4 lysine methylation. In addition, we observed down-regulation of DNA methyltransferase 1 (Dnmt1) and suppressor of variegation 3-9 homolog 1, a histone lysine methyltransferase (Suv39h1), and up-regulation of the histone demethylase Jumonji domain 2 (Jmjd2a), proteins responsible for the accurate maintenance of the epigenetic marks. Although the epigenetic effects were most pronounced in the 625-ppm exposure group, some effects were evident in mice exposed to 6.25 ppm BD.

Conclusions: This study demonstrates that exposure to BD leads to epigenetic alterations in the liver, which may be important contributors to the mode of BD carcinogenicity.

Show MeSH
Related in: MedlinePlus