title: New mechanism of γ-H2AX generation: Surfactant-induced actin disruption causes deoxyribonuclease I translocation to the nucleus and forms DNA double-strand breaks.
abstract: We previously showed that nonionic surfactants, nonylphenol polyethoxylates (NPEOs), induced phosphorylation of histone H2AX, forming γ-H2AX. In this study, we analyzed the mechanism of γ-H2AX generation by an NPEO with 15 ethylene oxide units (NPEO(15)). In MCF-7 breast carcinoma cells, NPEO(15) treatment induced γ-H2AX in a dose-dependent manner. EDTA and ZnCl2, two inhibitors of deoxyribonuclease I (DNase I), inhibited both the γ-H2AX and DNA double-strand breaks induced by NPEO(15). NPEO(15) disrupted filamentous actin and released free DNase I as detected by cell fractionation analysis. Based on immunofluorescence staining of DNase I and monitoring DNase I-GFP localization, DNase I was translocated from the cytosol to the nucleus of cells after treatment with NPEO(15). This translocation did not occur with the common DNA damage inducers ultraviolet B irradiation and hydrogen peroxide. Other surfactants, Tween 20, Triton X-100 and Nonidet P-40, also generated γ-H2AX. These results show that γ-H2AX induction by surfactants including NPEOs, occurs via a new mechanism involving release of free DNase I with actin disruption. This mechanism is distinct from the process of γ-H2AX generation caused by direct chemically induced DNA damage.
authors.affiliation: Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Xiaoxu
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Gang
authors.initials: G
authors.lastname: Yang
authors.affiliation: Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan; National Institute of Occupational Safety and Health, Kawasaki, Japan.
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Toyooka
authors.affiliation: Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan. Electronic address: ibuki@u-shizuoka-ken.ac.jp.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ibuki
mesh_terms: D000199:Actins / Q000737:chemistry*; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects*; D003850:Deoxyribonuclease I / Q000378:metabolism*; D005260:Female; D006657:Histones / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D061986:MCF-7 Cells; D017830:Octoxynol / Q000633:toxicity; D010766:Phosphorylation; D011092:Polyethylene Glycols / Q000633:toxicity; D011136:Polysorbates / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D013501:Surface-Active Agents / Q000633:toxicity*; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D000199:Actins; C468783:H2AX protein, human; D006657:Histones; D011136:Polysorbates; D017382:Reactive Oxygen Species; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; D017830:Octoxynol; C010615:Nonidet P-40; D006861:Hydrogen Peroxide; D003850:Deoxyribonuclease I
keywords: Actin; DNA double-strand breaks; Deoxyribonuclease I; Nonylphenol polyethoxylates; Surfactants; γ-H2AX