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

VIRGINIA LORENZ; MA. MERCEDES MILESI; MARLISE L. GUERRERO SCHIMPF,; ENRIQUE H. LUQUE; JORGELINA G. VARAYOUD

Congreso; Reunión Conjunta de Biociencias.; 2017

Previously, we showed that perinatal (in utero and lactational) exposure to a glyphosate based herbicide (GBH) produced subfertilityassociated with implantation failures in female rats. Implantationprocess is regulated by endocrine signaling pathways in which ERais one of the primary mediators. Five promoters (E1, OT, O, ON,and OS) control the ERa transcription initiation, yielding differenttranscripts with alternative 5´ untranslated regions (5?UTRs). Thiswork investigates whether a low dose of a GBH modifes uterineERa expression and induces epigenetic modifcations in its regulatory regions during the pre-implantation period. Pregnant rats (F0)were orally exposed to 200 mg of glyphosate/kg/day (NOAEL, EPA)through food, from gestational day (GD) 9 until weaning (lactationalday 21). When F1 females reached the sexual maturity, they werepregnant and uterine samples were collected on GD5 (pre-implantation period). ERa expression was determined using RT-qPCR. ERamRNA levels of transcript variants containing alternative 5´UTRswere also evaluated. Then we in silico evaluated the presence ofCpG islands and specifc restriction sites (for MaeII and BstUI) toanalyze the methylation status using Methylation-Sensitive Restriction Enzymes-PCR technique. Post-translational changes of histones were also studied by chromatin immunoprecipitation assay.GBH treatment increased total ERa mRNA expression mediated byan increased expression of ERa-O variant. GBH rats exhibited adecreased DNA methylation in one of the three sites evaluated inthe O promoter. In addition, we detected a higher level of histone4 acetylation and a decreased level of histone 3 methylation at Lys27. All these epigenetic changes are in accordance with the highertranscriptional activity of ERa in GBH treated rats. We demonstrated that low-dose perinatal GBH exposure induces lasting epigenetic disruption in the uterus possible related with the implantationfailures