Assessment of epigenetic modifications as mechanism of action of glyphosate

DONÁ F; LORENZ V; MILESI MM; VARAYOUD J

Mar del Plata

Congreso; LXVIII Reunión Anual de la Sociedad Argentina de Investigación Clínica (SAIC); 2023

SAIC

Previously, we detected that perinatal exposure to a glyphosate-based herbicide (GBH) or glyphosate (Gly), its active ingredient, induces implantation failure in rats. Hence, we investigated whether epigenetic alterations in the rat uterus during the receptive stage could be a possible mechanism of action of the herbicide implicated in the implantation failures. F0 dams were exposed to a GBH or Gly through food in a dose of 2 mg Gly/kg bw/day, from gestational day (GD) 9 until lactational day 21. F1 adult female rats were pregnant and uterine tissues were analyzed on GD5 (preimplantation period). The transcripts levels of Hoxa10 gene, a key molecule for endometrial receptivity, and major epigenetic enzymes were assessed by RT-qPCR. To analyze the methylation status of Hoxa10, enzyme-specific restriction sites were searched in silico in the regulatory regions of this gene and assessed using the methylation-sensitive restriction enzyme-PCR technique. To determine changes in histone post-translational modifications, histone 3 and 4 acetylation (H3Ac and H4Ac), and histone 3 methylation (H3K27me3) along the different regulatory regions of Hoxa10 were evaluated by chromatin immunoprecipitation assays. GBH and Gly reduced Hoxa10 mRNA expression in association with increased DNA methylation. Moreover, GBH and Gly exposure increased histone H3 and H4 acetylation and enriched H3K27me3 marker at three out of four sites analyzed. GBH and Gly increased mRNA transcripts of Enhancer of Zeste homolog 2 (EZH2) enzyme which specifically methylates H3K27. In conclusion, both GBH and Gly induce epigenetic changes that might explain the down-regulation of Hoxa10 gene. We propose that Gly and GBH could act through similar disruption pathways, as comparable results were detected.