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Arsenic Trioxide Reduces Global Histone H4 Acetylation at Lysine 16 through Direct Binding to Histone Acetyltransferase hMOF in Human Cells.

Liu D, Wu D, Zhao L, Yang Y, Ding J, Dong L, Hu L, Wang F, Zhao X, Cai Y, Jin J - PLoS ONE (2015)

Bottom Line: Our data show that decreased global H4K16ac and increased deacetyltransferase HDAC4 expression occurred in arsenic trioxide (As2O3)-exposed HeLa or HEK293T cells.However, depletion of HDAC4 did not affect global H4K16ac, and it could not raise H4K16ac in cells exposed to As2O3, suggesting that HDAC4 might not directly be involved in histone H4K16 de-acetylation.In an in vitro HAT assay, As2O3 directly inhibited hMOF activity. hMOF over-expression not only increased resistance to As and caused less toxicity, but also effectively reversed reduced H4K16ac caused by As exposure.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Jilin University, Changchun, Jilin 130012, China; School of Pharmacy, Changchun University of Traditional Chinese Medicine, Changchun 130117, China.

ABSTRACT
Histone post-translational modification heritably regulates gene expression involved in most cellular biological processes. Experimental studies suggest that alteration of histone modifications affects gene expression by changing chromatin structure, causing various cellular responses to environmental influences. Arsenic (As), a naturally occurring element and environmental pollutant, is an established human carcinogen. Recently, increasing evidence suggests that As-mediated epigenetic mechanisms may be involved in its toxicity and carcinogenicity, but how this occurs is still unclear. Here we present evidence that suggests As-induced global histone H4K16 acetylation (H4K16ac) partly due to the direct physical interaction between As and histone acetyltransferase (HAT) hMOF (human male absent on first) protein, leading to the loss of hMOF HAT activity. Our data show that decreased global H4K16ac and increased deacetyltransferase HDAC4 expression occurred in arsenic trioxide (As2O3)-exposed HeLa or HEK293T cells. However, depletion of HDAC4 did not affect global H4K16ac, and it could not raise H4K16ac in cells exposed to As2O3, suggesting that HDAC4 might not directly be involved in histone H4K16 de-acetylation. Using As-immobilized agarose, we confirmed that As binds directly to hMOF, and that this interaction was competitively inhibited by free As2O3. Also, the direct interaction of As and C2CH zinc finger peptide was verified by MAIDI-TOF mass and UV absorption. In an in vitro HAT assay, As2O3 directly inhibited hMOF activity. hMOF over-expression not only increased resistance to As and caused less toxicity, but also effectively reversed reduced H4K16ac caused by As exposure. These data suggest a theoretical basis for elucidating the mechanism of As toxicity.

No MeSH data available.


Related in: MedlinePlus

Over-expression of hMOF inhibited cell sensitivity to As2O3 in 293T cells.(A) Representative flow cytogram of Annexin V binding (X-axis) versus PI uptake (Y-axis) in 293T cells. Numbers in the upper left and right, lower left and right quadrants represent percentage of damaged, necrotic, live and apoptotic cells, respectively. (B) Quantified percentage of damaged and necrotic cells for (A). Statistical significant difference expressed as **p<0.01 (Student t-test). (C) Reversion of declined H4K16ac in As2O3-exposed 293T cells. 48 h after As2O3 treatment (0.2 and 0.4 μM), cells were harvested and lysed. hMOF and global modification of H4K16ac were measured.
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pone.0141014.g005: Over-expression of hMOF inhibited cell sensitivity to As2O3 in 293T cells.(A) Representative flow cytogram of Annexin V binding (X-axis) versus PI uptake (Y-axis) in 293T cells. Numbers in the upper left and right, lower left and right quadrants represent percentage of damaged, necrotic, live and apoptotic cells, respectively. (B) Quantified percentage of damaged and necrotic cells for (A). Statistical significant difference expressed as **p<0.01 (Student t-test). (C) Reversion of declined H4K16ac in As2O3-exposed 293T cells. 48 h after As2O3 treatment (0.2 and 0.4 μM), cells were harvested and lysed. hMOF and global modification of H4K16ac were measured.

Mentions: To confirm that As-produced global hypo-acetylation of H4K16 is due to reduced HAT activity of hMOF, we measured over-expression of hMOF with respect to cell sensitivity to As2O3. Flow cytometry of Annexin V binding/PI uptake was assessed in As2O3-exposed 293T cells (Fig 5A). Apoptosis is depicted in Fig 5B. Over expression of hMOF in As2O3-exposed 293T cells significantly inhibited necrosis at 3.2 μM As2O3 compared to vector only controls (*p<0.05). However, no statistical significant difference in damaged cells and apoptosis was observed between vector and hMOF ever-expressed groups (p>0.05). In addition, over-expression of hMOF blocked As2O3-induced global histone H4K16ac in 293T cells (Fig 5C). Therefore, over-expression of hMOF increased resistance to As2O3 and decreased toxicity in 293T cells. In contrast, knocking down hMOF in HeLa cells increased cell sensitivity to As2O3 (Fig 6A). Fig 6B and 6C show that knocking down hMOF in As2O3-exposed HeLa cells caused cell damage and death (**p<0.01 and *p<0.05, respectively) (**p<0.01 in both As2O3 groups) in As2O3-exposed HeLa cells.


Arsenic Trioxide Reduces Global Histone H4 Acetylation at Lysine 16 through Direct Binding to Histone Acetyltransferase hMOF in Human Cells.

Liu D, Wu D, Zhao L, Yang Y, Ding J, Dong L, Hu L, Wang F, Zhao X, Cai Y, Jin J - PLoS ONE (2015)

Over-expression of hMOF inhibited cell sensitivity to As2O3 in 293T cells.(A) Representative flow cytogram of Annexin V binding (X-axis) versus PI uptake (Y-axis) in 293T cells. Numbers in the upper left and right, lower left and right quadrants represent percentage of damaged, necrotic, live and apoptotic cells, respectively. (B) Quantified percentage of damaged and necrotic cells for (A). Statistical significant difference expressed as **p<0.01 (Student t-test). (C) Reversion of declined H4K16ac in As2O3-exposed 293T cells. 48 h after As2O3 treatment (0.2 and 0.4 μM), cells were harvested and lysed. hMOF and global modification of H4K16ac were measured.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4608833&req=5

pone.0141014.g005: Over-expression of hMOF inhibited cell sensitivity to As2O3 in 293T cells.(A) Representative flow cytogram of Annexin V binding (X-axis) versus PI uptake (Y-axis) in 293T cells. Numbers in the upper left and right, lower left and right quadrants represent percentage of damaged, necrotic, live and apoptotic cells, respectively. (B) Quantified percentage of damaged and necrotic cells for (A). Statistical significant difference expressed as **p<0.01 (Student t-test). (C) Reversion of declined H4K16ac in As2O3-exposed 293T cells. 48 h after As2O3 treatment (0.2 and 0.4 μM), cells were harvested and lysed. hMOF and global modification of H4K16ac were measured.
Mentions: To confirm that As-produced global hypo-acetylation of H4K16 is due to reduced HAT activity of hMOF, we measured over-expression of hMOF with respect to cell sensitivity to As2O3. Flow cytometry of Annexin V binding/PI uptake was assessed in As2O3-exposed 293T cells (Fig 5A). Apoptosis is depicted in Fig 5B. Over expression of hMOF in As2O3-exposed 293T cells significantly inhibited necrosis at 3.2 μM As2O3 compared to vector only controls (*p<0.05). However, no statistical significant difference in damaged cells and apoptosis was observed between vector and hMOF ever-expressed groups (p>0.05). In addition, over-expression of hMOF blocked As2O3-induced global histone H4K16ac in 293T cells (Fig 5C). Therefore, over-expression of hMOF increased resistance to As2O3 and decreased toxicity in 293T cells. In contrast, knocking down hMOF in HeLa cells increased cell sensitivity to As2O3 (Fig 6A). Fig 6B and 6C show that knocking down hMOF in As2O3-exposed HeLa cells caused cell damage and death (**p<0.01 and *p<0.05, respectively) (**p<0.01 in both As2O3 groups) in As2O3-exposed HeLa cells.

Bottom Line: Our data show that decreased global H4K16ac and increased deacetyltransferase HDAC4 expression occurred in arsenic trioxide (As2O3)-exposed HeLa or HEK293T cells.However, depletion of HDAC4 did not affect global H4K16ac, and it could not raise H4K16ac in cells exposed to As2O3, suggesting that HDAC4 might not directly be involved in histone H4K16 de-acetylation.In an in vitro HAT assay, As2O3 directly inhibited hMOF activity. hMOF over-expression not only increased resistance to As and caused less toxicity, but also effectively reversed reduced H4K16ac caused by As exposure.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Jilin University, Changchun, Jilin 130012, China; School of Pharmacy, Changchun University of Traditional Chinese Medicine, Changchun 130117, China.

ABSTRACT
Histone post-translational modification heritably regulates gene expression involved in most cellular biological processes. Experimental studies suggest that alteration of histone modifications affects gene expression by changing chromatin structure, causing various cellular responses to environmental influences. Arsenic (As), a naturally occurring element and environmental pollutant, is an established human carcinogen. Recently, increasing evidence suggests that As-mediated epigenetic mechanisms may be involved in its toxicity and carcinogenicity, but how this occurs is still unclear. Here we present evidence that suggests As-induced global histone H4K16 acetylation (H4K16ac) partly due to the direct physical interaction between As and histone acetyltransferase (HAT) hMOF (human male absent on first) protein, leading to the loss of hMOF HAT activity. Our data show that decreased global H4K16ac and increased deacetyltransferase HDAC4 expression occurred in arsenic trioxide (As2O3)-exposed HeLa or HEK293T cells. However, depletion of HDAC4 did not affect global H4K16ac, and it could not raise H4K16ac in cells exposed to As2O3, suggesting that HDAC4 might not directly be involved in histone H4K16 de-acetylation. Using As-immobilized agarose, we confirmed that As binds directly to hMOF, and that this interaction was competitively inhibited by free As2O3. Also, the direct interaction of As and C2CH zinc finger peptide was verified by MAIDI-TOF mass and UV absorption. In an in vitro HAT assay, As2O3 directly inhibited hMOF activity. hMOF over-expression not only increased resistance to As and caused less toxicity, but also effectively reversed reduced H4K16ac caused by As exposure. These data suggest a theoretical basis for elucidating the mechanism of As toxicity.

No MeSH data available.


Related in: MedlinePlus