GCNA is a histone binding protein required for spermatogonial stem cell maintenance

Recycling and de-novo deposition of histones during DNA replication is a critical challenge faced by eukaryotic cells and is coordinated by histone chaperones. However, little is known about how tissue-specific histone chaperones function to maintain tissue homeostasis. Here we show that Germ Cell Nuclear Acidic protein (GCNA), a germ cell specific protein in adult mice, can bind histones and purified GCNA exhibits histone chaperone activity. GCNA associates with the DNA replication machinery and supports progression through S-phase in murine spermatogonial stem cells (SSCs). Whilst GCNA is dispensable for embryonic germ cell development, it is required for the maintenance of the SSC pool and for long-term production of sperm. Our work describes the role of a germ cell specific histone chaperone in SSCs maintenance in mice. These findings provide a mechanistic basis for the male infertility observed in patients carrying mutations in the GCNA locus.