Immortalized Mouse Distal Caput Epididymal Epithelial Cell Line (DC2)

Epididymal Glucocorticoid Receptors Promote Intergenerational Transmission of Paternal Stress

Paternal preconception exposures, including stress and diet, can shape offspring health outcomes. Mechanistic studies suggest that small noncoding RNAs in sperm, such as microRNAs (miRs), carry paternal environmental information. However, the cellular mechanisms of how these signals are relayed to sperm and persist remain unknown.

To identify the molecular and epigenetic marks involved in the persistence of sperm miR alterations by stress, Chan et al. exposed male mice to chronic stress and collected epididymal sperm 1 or 12 weeks post-stress (Fig. 1a, top) to compare acute and enduring effects. Small RNA sequencing revealed two distinct populations of differentially expressed sperm miRs with no shared stress-altered miRs between them (Fig. 1b), suggesting a unique mechanism induces enduring changes in sperm miR populations following the acute stress response. To investigate how epigenetic changes in epididymal extracellular vesicles (EVs) are maintained after paternal stress, they treated DC2 mouse caput epididymal epithelial cells with corticosterone in vitro. This allowed them to isolate EVs from a specific cell population and control corticosterone administration. They tested three corticosterone concentrations (low, medium, and high) at three time points to examine acute, intermediate, and enduring effects (Fig. 1a, bottom). Using rank-rank hypergeometric overlap (RRHO) analyses, they compared in vivo stress-altered miRs with in vitro corticosterone-altered miRs. The overlap increased dramatically at 8 days compared to 1-day post-treatment (Fig. 1c). The 8-day time point with stress-relevant corticosterone concentration most closely matched in vivo enduring paternal stress effects (Fig. 1d), with 31.4% overlapping miRs (116/369). This suggests enduring effects in the in vitro model, though sperm miR complexity reflects additional interactions along the reproductive tract.

Fig. 1. Glucocorticoid-treated DC2 mouse caput epididymal epithelial cell EVs in vitro mimic paternal stress programming of enduring sperm miRs in vivo (Chan JC, Nugen BM, et al., 2018).