title: From the Cover: Sperm Molecular Biomarkers Are Sensitive Indicators of Testicular Injury following Subchronic Model Toxicant Exposure.
abstract: Traditional testis histopathology endpoints remain the gold standard for evaluating testicular insult and injury in a non-clinical setting, but are invasive and unfeasible for monitoring these effects clinically in humans. Assessing testicular injury in humans relies on semen and serum hormone analyses, both of which are insensitive and poor indicators of effect. Therefore, we hypothesized that sperm messenger RNA (mRNA) transcripts and DNA methylation marks can be used as translatable and sensitive indicators or testicular injury. Dose-response studies using adult male Fischer 344 rats subchronically exposed to model Sertoli cell toxicants (0.14, 0.21, and 0.33% 2,5-hexanedione, and 30, 50, and 70 mg/kg/day carbendazim), and a model germ cell toxicant (1.4, 3.4, and 5.1 mg/kg/day cyclophosphamide) for 3 months were evaluated for testicular injury by traditional histopathological endpoints, changes in sperm mRNA transcript levels using custom PCR arrays, and alterations in sperm DNA methylation via reduced representation bisulfite sequencing. Testis histopathological evaluation and PCR array analysis of the sperm transcriptome identified dose-dependent changes elicited by toxicant exposure (P < 0.05). Global sperm DNA methylation analysis of subchronic 0.33% 2,5-hexandione and 5.1 mg/kg/day cyclophosphamide exposure using a Monte Carlo approach did not identify differentially methylated regions (methylation difference > 10% and q < 0.05) with robust signatures. Overall, these results suggest that sperm mRNA transcripts are sensitive indicators of low dose toxicant-induced testicular injury in the rat, while sperm DNA methylation changes are not. Additionally, the Monte Carlo analysis is a powerful approach that can be used to assess the robustness of signals resulting from -omic studies.
authors.affiliation: *Division of Urology, Rhode Island Hospital, Providence, Rhode Island 02903 Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island 02912 edward_dere@brown.edu.
authors.forename: Edward
authors.initials: E
authors.lastname: Dere
authors.affiliation: Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island 02912.
authors.forename: Shelby K
authors.initials: SK
authors.lastname: Wilson
authors.affiliation: Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island 02912.
authors.forename: Linnea M
authors.initials: LM
authors.lastname: Anderson
authors.affiliation: Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island 02912.
authors.forename: Kim
authors.initials: K
authors.lastname: Boekelheide
mesh_terms: D000818:Animals; D001562:Benzimidazoles / Q000633:toxicity*; D015415:Biomarkers / Q000378:metabolism*; D001835:Body Weight / Q000187:drug effects; D002219:Carbamates / Q000633:toxicity*; D003520:Cyclophosphamide / Q000633:toxicity*; D019175:DNA Methylation; D004305:Dose-Response Relationship, Drug; D006588:Hexanones / Q000633:toxicity*; D008297:Male; D009929:Organ Size / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D013094:Spermatozoa / Q000187:drug effects* / Q000378:metabolism; D013737:Testis / Q000187:drug effects* / Q000378:metabolism
chemical_list: D001562:Benzimidazoles; D015415:Biomarkers; D002219:Carbamates; D006588:Hexanones; D012333:RNA, Messenger; D003520:Cyclophosphamide; C011269:2,5-hexanedione; C006698:carbendazim
keywords: DNA methylation; RNA; biomarkers; epigenetics; sperm; testis