title: Quantitative Mass Spectrometry Reveals Changes in Histone H2B Variants as Cells Undergo Inorganic Arsenic-Mediated Cellular Transformation.
abstract: Exposure to inorganic arsenic, a ubiquitous environmental toxic metalloid, leads to carcinogenesis. However, the mechanism is unknown. Several studies have shown that inorganic arsenic exposure alters specific gene expression patterns, possibly through alterations in chromatin structure. While most studies on understanding the mechanism of chromatin-mediated gene regulation have focused on histone post-translational modifications, the role of histone variants remains largely unknown. Incorporation of histone variants alters the functional properties of chromatin. To understand the global dynamics of chromatin structure and function in arsenic-mediated carcinogenesis, analysis of the histone variants incorporated into the nucleosome and their covalent modifications is required. Here we report the first global mass spectrometric analysis of histone H2B variants as cells undergo arsenic-mediated epithelial to mesenchymal transition. We used electron capture dissociation-based top-down tandem mass spectrometry analysis validated with quantitative reverse transcription real-time polymerase chain reaction to identify changes in the expression levels of H2B variants in inorganic arsenic-mediated epithelial-mesenchymal transition. We identified changes in the expression levels of specific histone H2B variants in two cell types, which are dependent on dose and length of exposure of inorganic arsenic. In particular, we found increases in H2B variants H2B1H/1K/1C/1J/1O and H2B2E/2F, and significant decreases in H2B1N/1D/1B as cells undergo inorganic arsenic-mediated epithelial-mesenchymal transition. The analysis of these histone variants provides a first step toward an understanding of the functional significance of the diversity of histone structures, especially in inorganic arsenic-mediated gene expression and carcinogenesis.
authors.affiliation: From the ‡Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536;
authors.forename: Matthew
authors.initials: M
authors.lastname: Rea
authors.affiliation: §Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306;
authors.forename: Tingting
authors.initials: T
authors.lastname: Jiang
authors.affiliation: From the ‡Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536;
authors.forename: Rebekah
authors.initials: R
authors.lastname: Eleazer
authors.affiliation: From the ‡Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536;
authors.forename: Meredith
authors.initials: M
authors.lastname: Eckstein
authors.affiliation: §Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306; ¶Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310.
authors.forename: Alan G
authors.initials: AG
authors.lastname: Marshall
authors.affiliation: From the ‡Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536; y.fondufe-mittendorf@uky.edu.
authors.forename: Yvonne N
authors.initials: YN
authors.lastname: Fondufe-Mittendorf
mesh_terms: D001151:Arsenic / Q000633:toxicity*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000378:metabolism; D002843:Chromatin / Q000187:drug effects / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D058750:Epithelial-Mesenchymal Transition; D014644:Genetic Variation / Q000187:drug effects; D006367:HeLa Cells; D006657:Histones / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D002843:Chromatin; D006657:Histones; D001151:Arsenic