DAXX governs the silencing of LINE1 during 1 spermatogenesis in mice

The disinhibition of transposon elements (TEs) is a significant threat to male reproduction, particularly during the delicate process of spermatogenesis. Here we identify that Death associated protein 6 (Daxx), a potent transcription repressor and an H3.3 chaperone essential for the TEs silencing during spermatogenesis. DAXX-deficient mouse display delayed meiotic progression, reduced production of spermatids, deformed spermatozoa and age-dependent decline in male fertility. We demonstrate that young long-interspersed nuclear elements (LINE1) and endogenous retroviral elements (ERVs) subfamilies, were upregulated in meiotic spermatocytes of Daxx null testes. Further study found that the Daxx mutant meiotic cells exhibit DNA hypomethylation in TEs. In summary, we have identified DAXX as a previously unknown key regulator of spermatogenesis that may function as an epigenetic regulator to silence young LINE1 by DNA methylation.