DNA double-strand break repair in male germ cells during spermatogenesis and its association with male infertility development.

Spermatogenesis is a complex developmental process. During this process, male germ cells from spermatogonia to sperm cells encounter a number of DNA damages. The most severe form of these damages is double-strand breaks (DSBs) deriving from exogenous and endogenous genotoxic insults. DSBs must be correctly repaired in a short time to maintain genomic integrity in the male germ cells. For this purpose, there are four pathways working in repair of DSBs: homologous recombination (HR), classical non-homologous end joining (cNHEJ), alternative end joining (aEJ), and single strand annealing (SSA). While the HR pathway repairs DSBs with a homology-based and error-free manner, the cNHEJ, aEJ, and SSA pathways join free ends in a sequence-independent mechanism. Possible impairments in these DSB repair mechanisms can lead to cell cycle arrest, abnormal meiotic recombination, and ultimately male infertility. In this review, we comprehensively introduce DSB repair pathways being used by male germ cells during spermatogenesis. Also, potential relationship between dysfunction in these pathways and male infertility development are discussed in the light of existing studies.