The arginine methyltransferase PRMT1 establishes transcriptomic homeostasis essential for spermatogonial differentiation and male fertility

Protein arginine methyltransferase 1 (Prmt1) is known as the major Type-I protein arginine methyltransferase that deposits asymmetrical dimethylarginine (ADMA) in both histone and non-histone substrates. Nonetheless, how Prmt1 and its downstream signalling through substrate methylation function in the male germline development remains poorly understood. In this study, we discovered that Prmt1 is predominantly present in the spermatogonial population during mouse spermatogenesis. Using three Cre-mediated conditional Prmt1 knockout mouse lines, we observed that Prmt1 is essential for the maintenance of spermatogonial cells and Prmt1-deposited ADMA marks coordinate an inherent homeostasis among three types of substrate methylation. In conjunction with high-throughput Cut&Tag and modified mini-bulk Smart-seq2 analyses, we unveiled that Prmt1-mediated H4R3me2a mark enriched in the promoter region, together with other histone arginine methylations, drives a global transcriptomic landscape that maintains the regular gene expression and alternative splicing. Collectively, we provide the genetic evidence showing the essential role of Prmt1-deposited arginine methylation in the establishment of transcriptional homeostasis, and shed light on the methylarginine signalling pathway in orchestrating spermatogonial development in the mammalian germline. We used WT and Prmt1 conditional knockout samples for all the experiments through tamoxifen injection for 3 days. For WT CUT&Tag we used C57BL/6J