title: Alcohol-induced epigenetic alterations to developmentally crucial genes regulating neural stemness and differentiation.
abstract: BACKGROUND
  From studies using a diverse range of model organisms, we now acknowledge that epigenetic changes to chromatin structure provide a plausible link between environmental teratogens and alterations in gene expression leading to disease. Observations from a number of independent laboratories indicate that ethanol (EtOH) has the capacity to act as a powerful epigenetic disruptor and potentially derail the coordinated processes of cellular differentiation. In this study, we sought to examine whether primary neurospheres cultured under conditions maintaining stemness were susceptible to alcohol-induced alterations in the histone code. We focused our studies on trimethylated histone 3 lysine 4 and trimethylated histone 3 lysine 27, as these are 2 of the most prominent posttranslational histone modifications regulating stem cell maintenance and neural differentiation.
  
  
  METHODS
  Primary neurosphere cultures were maintained under conditions promoting the stem cell state and treated with EtOH for 5 days. Control and EtOH-treated cellular extracts were examined using a combination of quantitative RT-PCR and chromatin immunoprecipitation techniques.
  
  
  RESULTS
  We find that the regulatory regions of genes controlling both neural precursor cell identity and processes of differentiation exhibited significant declines in the enrichment of the chromatin marks examined. Despite these widespread changes in chromatin structure, only a small subset of genes including Dlx2, Fabp7, Nestin, Olig2, and Pax6 displayed EtOH-induced alterations in transcription. Unexpectedly, the majority of chromatin-modifying enzymes examined including members of the Polycomb Repressive Complex displayed minimal changes in expression and localization. Only transcripts encoding Dnmt1, Uhrf1, Ehmt1, Ash2 l, Wdr5, and Kdm1b exhibited significant differences.
  
  
  CONCLUSIONS
  Our results indicate that primary neurospheres maintained as stem cells in vitro are susceptible to alcohol-induced perturbation of the histone code and errors in the epigenetic program. These observations indicate that alterations to chromatin structure may represent a crucial component of alcohol teratogenesis and progress toward a better understanding of the developmental origins of fetal alcohol spectrum disorders.
authors.affiliation: College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4466, USA.
authors.forename: Kylee J
authors.initials: KJ
authors.lastname: Veazey
authors.forename: Mindy N
authors.initials: MN
authors.lastname: Carnahan
authors.forename: Daria
authors.initials: D
authors.lastname: Muller
authors.forename: Rajesh C
authors.initials: RC
authors.lastname: Miranda
authors.forename: Michael C
authors.initials: MC
authors.lastname: Golding
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D044127:Epigenesis, Genetic / Q000187:drug effects* / Q000502:physiology; D000431:Ethanol / Q000633:toxicity*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D008810:Mice, Inbred C57BL; D058953:Neural Stem Cells / Q000187:drug effects* / Q000502:physiology; D011247:Pregnancy
chemical_list: D000431:Ethanol
keywords: Bivalent Genes; Chromatin; Epigenetic Programming; Fetal Alcohol Syndrome; Neural Stem Cells