Epigenetic disruption of estrogen receptor alpha following perinatal exposure to a glyphosate-based herbicide

LORENZ V; MILESI MM; GUERRERO SCHIMPF M; LUQUE EH; VARAYOUD J

Buenos Aires

Congreso; LXII Reunión Anual de la Sociedad Argentina de Investigación Clínica; 2017

Sociedad Argentina de Investigación Clínica (SAIC)

Previously, we showed that perinatal (in utero and lactational) exposure to a glyphosate based herbicide(GBH) produced subfertility associated with implantation failures in femalerats. Implantation process is regulated by endocrine signaling pathways inwhich ERa is one of the primary mediators. Five promoters (E1, OT, O, ON, and OS) control theERa transcription initiation, yielding different transcripts withalternative 5´ untranslated regions (5?UTRs). This work investigates whether alow dose of a GBH modifies uterine ERa expression and inducesepigenetic modifications in its regulatory regions during the pre-implantation period.Pregnant rats (F0) were orally exposed to 200 mg ofglyphosate/kg/day (NOAEL, EPA) through food, from gestational day (GD) 9 untilweaning (lactational day 21). When F1 females reached the sexual maturity, theywere pregnant and uterine samples were collected on GD5 (pre-implantationperiod). ERa expression was determined using RT-qPCR. ERa mRNA levels of transcript variants containing alternative 5´UTRs werealso evaluated. Then we in silico evaluatedthe presence of CpG islands and specific restriction sites (for MaeII and BstUI) to analyze the methylation status usingMethylation-Sensitive Restriction Enzymes-PCR technique. Post-translational changesof histones were also studied by chromatin immunoprecipitation assay. GBH treatment increased total ERa mRNA expression mediated by an increased expressionof ERa-O variant. GBH rats exhibited a decreased DNA methylation in oneof the three sites evaluated in the O promoter. In addition, we detected ahigher level of histone 4 acetylation and a decreased level of histone 3 methylationat Lys 27. All these epigenetic changes are in accordance with the highertranscriptional activity of ERa in GBH treated rats. We demonstratedthat low-dose perinatal GBH exposure induces lasting epigenetic disruption inthe uterus possible related with the implantation failures.  Keywords: Glyphosate based herbicide, Uterus, Estrogen receptoralpha, Epigenetic regulation