Ex Vivo Exposures to Inorganic Arsenic and its Methylated Metabolites Alter Gene Transcription in Mouse Sperm Cells

Chronic exposure to inorganic arsenic (iAs) has been linked to diabetic phenotypes in both humans and mice. A previous study from our laboratory suggested that preconception iAs exposure may contribute to the development of diabetic phenotype in male offspring mediated through alterations in sperm gene expressions. However, individual contributions of iAs and its methylated metabolites to changes in sperm transcriptome cannot be determined using in vivo exposure. The goal of the present study was to assess transcriptomic changes in mouse sperm in response to trivalent iAs, monomethylated arsenic (MMAs) and dimethylated arsenic (DMAs), using an ex vivo model. We exposed freshly isolated sperm to non-cytotoxic concentrations of the three trivalent arsenicals (0.1 or 1 µM) for 4 hours and used RNA-sequencing to identify differentially expressed genes and the corresponding pathways. We also identified functional protein networks associated with these genes and pathways. We found that exposures to low concentrations of the trivalent arsenicals (0.1 µM) had greater effects on gene expression than exposures to 1 µM, with the most robust effect being associated with exposure to 0.1 µM MMAs. ATP binding was the most significantly enriched pathway in sperm exposed to iAs and MMAs; pathways associated with DNA binding and transcription were most enriched in sperm exposed to DMAs. There was no overlap between gene transcripts altered by ex vivo exposures and those altered in sperm in the published preconception exposure study. However, two pathways that were found to be significantly enriched in the preconception exposure study, namely focal adhesion and ECM receptor interaction pathways, were also among the significantly enriched pathways in the sperm exposed ex vivo to 0.1 µM iAs and MMAs. Seven proteins associated with both ECM functions and focal adhesion were identified in sperm exposed ex vivo to 0.1 µM iAs and MMAs, suggesting a potential interaction between the pathways.Bachelor of Science in Public Healt