title: CB1-receptor knockout neonatal mice are protected against ethanol-induced impairments of DNMT1, DNMT3A, and DNA methylation.
abstract: The significant consequences of ethanol use during pregnancy are neurobehavioral abnormalities involving hippocampal and neocortex malfunctions that cause learning and memory deficits collectively named fetal alcohol spectrum disorder. However, the molecular mechanisms underlying these abnormalities are still poorly understood and therefore warrant systematic research. Here, we document novel epigenetic abnormalities in the mouse model of fetal alcohol spectrum disorder. Ethanol treatment of P7 mice, which induces activation of caspase 3, impaired DNA methylation through reduced DNA methyltransferases (DNMT1 and DNMT3A) levels. Inhibition of caspase 3 activity, before ethanol treatment, rescued DNMT1, DNMT3A proteins as well as DNA methylation levels. Blockade of histone methyltransferase (G9a) activity or cannabinoid receptor type-1 (CB1R), prior to ethanol treatment, which, respectively, inhibits or prevents activation of caspase 3, rescued the DNMT1 and DNMT3A proteins and DNA methylation. No reduction of DNMT1 and DNMT3A proteins and DNA methylation was found in P7 CB1R null mice, which exhibit no ethanol-induced activation of caspase 3. Together, these data demonstrate that ethanol-induced activation of caspase 3 impairs DNA methylation through DNMT1 and DNMT3A in the neonatal mouse brain, and such impairments are absent in CB1R null mice. Epigenetic events mediated by DNA methylation may be one of the essential mechanisms of ethanol teratogenesis. Schematic mechanism of action by which ethanol impairs DNA methylation. Studies have demonstrated that ethanol has the capacity to bring epigenetic changes to contribute to the development of fetal alcohol spectrum disorder (FASD). However, the mechanisms are not well studied. P7 ethanol induces the activation of caspase 3 and impairs DNA methylation through reduced DNA methyltransferases (DNMT1 and DNMT3A) proteins (→). The inhibition or genetic ablation of cannabinoid receptor type-1 or inhibition of histone methyltransferase (G9a) by Bix (-----) or inhibition of caspase 3 activation by Q- quinoline-Val-Asp(Ome)-CH2-O-phenoxy (Q-VD-OPh) () rescue loss of DNMT1, DNMT3A as well as DNA methylation. Hence, the putative DNMT1/DNMT3A/DNA methylation mechanism may have a potential regulatory role in FASD.
authors.affiliation: Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
authors.forename: Nagaraja N
authors.initials: NN
authors.lastname: Nagre
authors.affiliation: Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
authors.forename: Shivakumar
authors.initials: S
authors.lastname: Subbanna
authors.affiliation: Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.
authors.forename: Madhu
authors.initials: M
authors.lastname: Shivakumar
authors.affiliation: Institute of Biosciences and Technology, Houston, Texas A&M University Health Science Center, Houston, TX 77030, USA.
authors.forename: Delphine
authors.initials: D
authors.lastname: Psychoyos
authors.affiliation: Division of Analytical Psychopharmacology, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA.|New York State Psychiatric Institute, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA.|Department of Psychiatry, College of Physicians & Surgeons, Columbia University, New York, NY 10032, USA.
authors.forename: Balapal S
authors.initials: BS
authors.lastname: Basavarajappa
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D019175:DNA Methylation / Q000187:drug effects* / Q000502:physiology*; D000090205:DNA Methyltransferase 3A; D000431:Ethanol / Q000633:toxicity*; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D043884:Receptor, Cannabinoid, CB1 / Q000172:deficiency*
chemical_list: C000715535:Dnmt3a protein, mouse; D043884:Receptor, Cannabinoid, CB1; D000431:Ethanol; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; C000619381:Dnmt1 protein, mouse
keywords: CB1R; caspase 3; epigenetics; fetal alcohol spectrum disorder; methyltransferase; neuronal loss