Sulforaphane protects against ethanol-induced apoptosis and teratogenesis through epigenetic modulation of anti-apoptotic genes.

Abstract

Background. Ethanol-induced excessive apoptosis in neural crest cells (NCCs), a multipotent progenitor cell population, is one of the major mechanisms underlying the pathogenesis of Fetal Alcohol Spectrum Disorders (FASD). However, the molecular mechanisms underlying FASD that results from maternal alcohol exposure during pregnancy are poorly understood. The overall goals of this study are to examine the mechanisms by which ethanol induces apoptosis and malformations in vitro and in vivo, and to develop a nutritional-based approach by using SFN and SFN-rich BSE to prevent FASD through epigenetic modulation. Results. This study demonstrates that ethanol exposure resulted in a significant increase in the DNMT activity and the expression of DNMT3a in human neural crest cells. SFN can significantly diminish ethanol-induced increases in DNMT activity and the expression of DNMT3a. We have also found that ethanol-induced up-regulation of DNMT3a and an increase in DNMT activity resulted in hypermethylation at the promoters of the selected anti-apoptotic genes and that SFN can diminish ethanol-induced hypermethylation at the promoters of the anti-apoptotic genes by preventing ethanol-induced up-regulation of DNMT3a and increase in DNMT activity. In addition, the knockdown of DNMT3a or treatment with SFN significantly diminished ethanol-induced decreases in the mRNA and protein expression of NAIP and XIAP and prevented ethanol-induced apoptosis in human neural crest cells. The knockdown of DNMT3a also enhanced the effects of SFN on the mRNA and protein expression of NAIP and XIAP and the protective effects of SFN on ethanol-induced apoptosis. This study also shows that ethanol exposure can increase HDAC activity and the expression of HDAC2 in human neural crest cells. SFN treatment significantly diminished ethanol-induced increase in HDAC activity and the up-regulation of HDAC2. We have also found that ethanol-induced increase in HDAC activity and up-regulation of HDAC2 resulted in the reduction of H3 acetylation at the promoters of AKT1, BIRC6 and XIAP and that SFN diminished ethanol-induced reduction of H3 acetylation at the promoters of anti-apoptotic genes by inhibiting HDAC activity and reducing ethanol-induced up-regulation of HDAC2. In addition, SFN treatment or knockdown of HDAC2 significantly diminished ethanol-induced decreases in the mRNA and protein expression of AKT1, BIRC6 and XIAP and prevented ethanol-induced apoptosis in human neural crest cells. The knockdown of HDAC2 also enhanced the effects of SFN on the mRNA and protein expression of AKT1, BIRC6 and XIAP and the protection against ethanol-induced apoptosis. In addition, our studies have shown that ethanol exposure can inhibit EMT