Single-nucleus multiomics of murine gonads reveals transcriptional regulatory network underlying supporting lineage differentiation.

Sex determination of mammalian gonads hinges upon sex-specific differentiation of gonadal supporting cells: Sertoli cells in the testis and granulosa cells in the ovary. To gain insights into how supporting cells acquire their identities, we performed joint single-nucleus transcriptomics and chromatin accessibility assays on murine gonadal cells during sex determination. By contrasting sex-specific gene expression and corresponding chromatin accessibility among progenitor and differentiated cells, we found that sex-specific chromatin regions in supporting cells are established shortly after sex determination, accompanied by the acquisition of active histone marks. The presence of potential transcription factor-binding motifs in the open chromatin regions revealed regulatory networks underlying ovary-enriched factors LEF1 and MSX1, which promote granulosa fate by inducing granulosa-specific genes such as Foxl2 and Fst. Our results not only identify the gene regulatory framework underlying supporting cell sex differentiation but also provide invaluable resources for the field.