Macrophage-derived exosomes carrying RAD50 attenuate oxidative DNA damage and p53–p21-dependent S-phase arrest in spermatogenic cells

Abstract

Occupational heat and blast overpressure impair spermatogenesis, and whether repair capacity supplied from outside the germ cell can lift the resulting block has not been tested. GC-2 spermatocytes received 1000 shock-wave pulses then 100°C for 40 s, and C57BL/6 mice received a 10% methane blast with intratesticular temperature unrecorded. Both were treated with exosomes from J774A.1 macrophages profiled by nanoparticle tracking and proteomics. Stress raised mitochondrial superoxide, lowered membrane potential and generated phosphorylated H2A.X (γ-H2AX) foci. Across 675 differentially expressed genes, glutathione metabolism was the most enriched pathway, at 7.13-fold and adjusted p = 7.07 × 10−6. p53 and p21 increased while cyclin-dependent kinase 2 (CDK2) and Cyclin A2 decreased, arresting a larger fraction of cells in S phase than in controls. RAD50 was detected among 3603 exosomal proteins and ranked in the top tier of the displayed abundance panel, and exosome treatment increased its co-precipitation with MRE11. Treatment also lowered superoxide, normalized the four-cycle regulators and returned the S-phase fraction toward control, with testis moving in the same direction. These data indicate that macrophage-derived exosomes relieve the redox-triggered p53–p21 checkpoint by supplying repair capacity.