MOF-containing non-specific lethal (NSL) complex has been found to have a wide range of targets, including H4K8, H4K5 and some non-histone proteins. PHF20 is a component of the NSL complex with the potential to bind methylated proteins via its Tudor1/2 and PHD domains. Such characteristics may permit PHF20 to bridge between histone methylation and acetylation dynamics. Histone modifications alter gene expression during male germ cell development and are necessary for some spermatogenesis-specific processes. Our preliminary experiments and published research suggest that both Phf20 and Mof are expressed in mouse testes. Phf20 is specifically upregulated in spermatogonial stem cells (SSCs), while Mof is more ubiquitously expressed in all spermatogenic cell types and tends to enrich in the Meiotic-phase spermatocytes. Therefore, we want to explore whether NSL complex has different compositions during spermatogenesis and determine its roles in cell lineages formation, focusing on PHF20 contribution. For this purpose, we will establish in vivo and in vitro models with cultured SSCs and mouse testes concerning PHF20 functional protein truncations. Multiple omics techniques and biochemical approaches will be combined in the investigation to reveal the biological meaning of this complex at different levels.