Bulk RNA-Seq of Inha KO mouse placenta exposed to DEHP

Introduction: In the placenta, activin A affects decidualisation and trophoblast growth and invasion. Levels increase during pregnancy to peak at parturition, while premature elevation is a hallmark of several pregnancy disorders. Here we examine the impact of elevated activin A bioactivity in the inhibin α knockout (Inha KO) mouse placenta. We also investigate whether simultaneous exposure to the endocrine disruptor, diethyl-hexyl phthalate (DEHP), which impairs normal placental function, exacerbates effects on placental morphology and gene expression in this model. Methods: Litters of Inha WT, Het and KO fetuses were collected at E15.5 from time-mated Inha heterozygous pregnant mice randomly assigned to three groups: untreated, corn oil (Vehicle) or DEHP 500 mg/kg/day, from E12.5-14.5 (n=2-17). Gross and histological placental morphology was analysed, and bulk RNA-sequencing conducted. Results: Placentae of Inha WT, Het and KO fetuses exhibited no gross differences, and no differentially expressed genes. However, sex differences included a significant increase in labyrinth area and placental size from WT males compared to WT females. DEHP exposure significantly increased fetal resorption at E15.5 but yielded little differences in placental morphology. Transcript analysis identified sex- and genotype-specific transcript alterations resulting from DEHP treatment. Eight transcripts were altered by DEHP exposure across all genotypes (Cts3, Ceacam13, Gm5155, Ssr4, Sec11c, Psg18, Psg-ps1, Taf7l). Discussion: Despite minimal morphological changes, transcriptomic differences suggest that spongiotrophoblast cells and syncytiotrophoblast giant cells are key targets of DEHP exposure, with CEA family transcripts susceptible to its effects. Additionally, DEHP exposure also modulates gene transcript responses to elevated activin A.