Aging Induces Profound Changes in sncRNA in Rat Sperm and these Changes are Modified by Perinatal Exposure to Environmental Flame Retardant

Abstract

Advanced paternal age at fertilization is a risk factor for multiple disorders in offspring and may be linked with age-related epigenetic changes in fathers sperm. Understanding of aging-related epigenetic changes in sperm and environmental factors that modify such changes is needed. Here we characterize changes in sperm sncRNA between young pubertal and mature rats. We also analyze modification of these changes by exposure to environmental xenobiotic 2,2’,4,4’-tetrabromodiphenyl ether (BDE-47). SncRNA libraries prepared from epididymal spermatozoa were sequenced and analyzed using DESeq 2. Distribution of small RNA fractions changed with age, with fractions mapping to rRNA and lncRNA decreasing and fractions mapping to tRNA and miRNA increasing. 249 miRNA, 908 piRNA and 227 tRNA-derived RNA were differentially expressed (2-fold change, FDR p ≤ 0.05) between age groups in control animals. Differentially expressed miRNA and piRNA were enriched for protein-coding targets involved in development and metabolism, piRNA were enriched for LTR targets. BDE-47 accelerated age dependent changes in sncRNA in younger animals, decelerated these changes in older animals and increased the variance in expression of all sncRNA. Our results indicate that the natural aging process has profound effects on sperm sncRNA profiles and this effect may be modified by environmental exposures.