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

LORENZ, VIRGINIA; MILESI, MARÍA MERCEDES; GUERRERO SCHIMPF, MARLISE; LUQUE, ENRIQUE HUGO; VARAYOUD, JORGELINA

Buenos aires

Congreso; Reunión conjunta de Sociedades de Biociencias - Sociedad Argentina de Investigación en Clínica (SAIC) - LXII Reunión Anual; 2017

SAIC, SAIB, SAI, SAFE, SAH, SAP, SAB, SAFIS, SAA

Previously, we showed that perinatal (in utero and lactational) exposure to a glyphosate based herbicide (GBH) produced subfertility associated with implantation failures in female rats. Implantation process is regulated by endocrine signaling pathways in which ER is one of the primary mediators. Five promoters (E1, OT, O, ON, and OS) control the ER transcription initiation, yielding different transcripts with alternative 5´ untranslated regions (5?UTRs). This work investigates whether a low dose of a GBH modifies uterine ER expression and induces epigenetic modifications 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 (lactational day 21). When F1 females reached the sexual maturity, they were pregnant and uterine samples were collected on GD5 (pre-implantation period). ER expression was determined using RT-qPCR. ER mRNA levels of transcript variants containing alternative 5´UTRs were also evaluated. Then we in silico evaluated the presence of CpG islands and specific restriction sites (for MaeII and BstUI) to analyze 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 ER mRNA expression mediated by an increased expression of ER-O variant. GBH rats exhibited a decreased DNA methylation in one of the three sites evaluated in the O promoter. In addition, we detected a higher level of histone 4 acetylation and a decreased level of histone 3 methylation at Lys 27. All these epigenetic changes are in accordance with the higher transcriptional activity of ER in GBH treated rats. We demonstrated that low-dose perinatal GBH exposure induces lasting epigenetic disruption in the uterus possible related with the implantation failures.