The SMARCA5–DMRT1 Pioneer Complex Establishes Epigenetic Priming to Direct Male Germline Development [ATAC-seq]

Establishing cell type–specific chromatin landscapes is essential for cellular identity, yet how these landscapes are generated and maintained remains poorly understood. Here, we demonstrate that the chromatin remodeler SMARCA5 facilitates epigenetic priming required for retinoic acid–induced differentiation in the male germline. Germ cell–specific deletion of Smarca5 results in a complete loss of differentiating spermatogonia, phenocopying vitamin A–deficient mice lacking retinoic acid signaling. During the perinatal transition from prospermatogonia to undifferentiated spermatogonia, SMARCA5 is recruited to DMRT1-binding sites located at distal putative enhancers and promoters of germline genes. The SMARCA5–DMRT1 pioneer complex establishes chromatin accessibility at these loci, generating poised enhancers and promoters that serve as retinoic acid receptor (RAR)–binding sites. Thus, SMARCA5 licenses transcriptional responses to retinoic acid that enable spermatogenic differentiation. Our findings uncover a critical epigenetic priming mechanism that links pioneer factor activity to external signal responsiveness in the germline.