In vivo labeling-based proteomic analysis of early follicle oocytes and cisplatin-induced alterations in mice.

A systematic proteomic profile of oocytes from early-stage follicles, particularly primordial follicles, is critical to protect female reproductive capacity in the context of chemotherapy, yet progress has been hindered by the rarity of oocyte samples and technical challenges associated with oocyte isolation. In this study, we generated in vivo oocyte protein labeling APEX fluorescent mice. With these mice, we reconstructed the ovary in 3D, enabling precise quantification of follicles and identified 2772 proteins and 2878 gene transcripts in oocytes predominantly from primordial follicles. Proteomic shifts of short-time cisplatin treatment revealed that many altered proteins were involved in DNA damage repair and histone modification. Notably, simultaneous application of cisplatin and EZH2's inhibitor, GSK126, relieved cisplatin-induced oocyte developmental defects. Our study provides a systematic proteomic characterization of oocytes predominantly from primordial follicles in female mice, and reveals dynamic proteome shifts in response to chemotherapeutic agents, laying the foundation for targeted fertility-preserving strategies.