The discovery of Female Germline Stem Cells (FGSCs) has transformed the field of reproductive biology, challenging the established notion that female mammals possess a fixed, nonrenewable reserve of oocytes at birth 1. Unlike Spermatogonial Stem Cells (SSCs), which continuously produce sperm throughout a male's reproductive life, FGSCs are believed to maintain the ability to produce eggs after birth, opening exciting possibilities for fertility restoration and regenerative therapies. Nevertheless, the molecular mechanisms that regulate FGSC maintenance and differentiation are still not well understood. One key regulator of germline development is c-Kit (KIT protooncogene, receptor tyrosine kinase), a membrane-bound receptor known for its essential role in primordial germ cell (PGC) survival, proliferation, and migration during embryogenesis 2. While SSCs downregulate c-Kit expression to maintain an undifferentiated state 3. The sustained expression of c-Kit in female germline cells suggests a distinct role in FGSCs, likely associated with their differentiation.

To investigate the molecular differences between male and female germline stem cells, we analyzed gene expression differences using microarray data from the GSE51313 dataset, generated using the Illumina MouseWG-6 v2.0 platform, which comprises three biological replicates for both SSCs and FGSCs 4. Data processing was performed using GEO2R, applying a log2 fold change threshold of >2 and an adjusted p-value <0.05 (Benjamini-Hochberg correction). Differentially expressed genes (DEGs) were visualized using the EnhancedVolcano package in R. We subsequently built Protein-Protein Interaction (PPI) networks utilizing the STRING database, analyzed network centrality using Cytoscape with the Centiscape plugin, and performed modularity clustering using Gephi (v0.10.1). The gene c-Kit, significantly upregulated in FGSCs, was selected as a key node for further module-based enrichment analysis.

Enrichment of the c-Kit module revealed the EGFR1 Signaling Pathway (WP572) as the most significantly enriched pathway (adjusted p-value = 0.00001037, combined score = 733.55), suggesting a functional interaction between c-Kit and EGFRmediated signaling in FGSC biology. Given that EGFR signaling is critical for cell survival, proliferation, and differentiation, its enrichment highlights a potential regulatory axis supporting FGSC maintenance or early differentiation.

In summary, our combined transcriptomic and network-based analysis highlights c-Kit and EGFR1 signaling as critical elements in the molecular profile differentiating FGSCs from SSCs. These findings provide novel insights into the sex-specific regulation of germline stem cells, offering a foundation for future studies aimed at harnessing FGSCs for therapeutic applications in reproductive medicine.