Transcriptomic Analysis Reveals the Molecular Mechanisms of Prolactin in Regulating Porcine Follicular Development

Prolactin (PRL) is a key reproductive hormone that regulates follicular development through endocrine and paracrine mechanisms. However, its specific role in porcine follicular development remains unclear.

In the in vivo experiments, follicular fluid and tissue cells were obtained from small (1-2 mm), medium (3-4 mm), and large (5-6 mm) porcine follicles. PRL levels in follicular fluid were measured by ELISA. The expression levels of genes and proteins related to follicular development were assessed using quantitative real-time PCR (RT-qPCR) and Western blotting (WB). In the in vitro experiments, CCK-8, RT-qPCR, and WB were used to detect the effects of different concentrations (0, 30, and 300 ng/mL) of recombinant porcine prolactin (prPRL) on granulosa cell (GC) proliferation, steroid hormone synthesis, and angiogenesis, and transcriptome sequencing was performed.

The PRL concentration was significantly higher in large follicles compared to small and medium follicles. During follicular development, expression levels of PRL, PRL receptor (PRLR), proteolytic enzymes (CTSD, MMP2, MMP14, and BMP-1), and angiogenic factors (VEGFA and FGF-2) increased and then decreased. Moreover, prPRL promoted GC proliferation, increased the expression of PCNA and cyclin D1, upregulated steroidogenesis-related genes CYP11A1 and 3β-HSD, and significantly enhanced the expression of key angiogenic factors VEGFA and FGF-2. RNA-seq analysis identified 226 differentially expressed genes (DEGs), which were mainly enriched in signaling pathways such as the Hippo, JAK/STAT, and Rap1 pathways.

PRL may regulate porcine follicle development by affecting cell proliferation and angiogenesis in GCs through the Hippo, JAK/STAT and Rap1 signaling pathways.