ASSESMENT OF EPIGENETIC MODIFICATIONS AS MECHANISM OF ACTION OF GLYPHOSATE

DONA F; LORENZ V; MILESI M; VARAYOUD J

Congreso; REUNIÓN CONJUNTA SAIC SAB AAFE AACYTAL 2023; 2023

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 if epigenetic modifications during the rat’s receptive stage could be a possible mechanism of action of the herbicide implicated in the implantation failures. F0 dams were exposed to 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 bred, and uterine tissues were analyzed on GD5 (preimplantation period). The transcripts levels of Hoxa10 (a key implantation gene) and epigenetic enzymes were assessed by RT-qPCR. To analyze the methylation status of Hoxa10, enzymes-specific restriction sites were searched in silico in the regulatory regions of the gene and assessed using the methylation-sensitive restriction enzymes-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 assessed by chromatin immunoprecipitation assays. GBH and Gly reduced Hoxa10 mRNA expression in association with an 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 Enhancer of Zeste homolog 2 (EZH2) enzyme mRNA transcript related with H3K27me3. In conclusion, perinatal herbicide exposure produce epigenetic modifications that could explain the down-regulation of Hoxa10 gene, a key molecule during implantation. Comparable results were detected with Gly and GBH suggesting similar disruption pathways.