Proteomic and metabolomic analysis of human follicular fluid from follicles with different diameters.

INTRODUCTION: Follicular fluid forms the essential microenvironment for oocyte growth and maturation, with its molecular features tightly correlated with oocyte developmental competence. Elucidating molecular differences in follicular fluid among follicles of different diameters is crucial for deciphering the mechanisms governing follicular development. METHODS: In this study, we constructed a proteome-metabolome database of human follicular fluid derived from small and large follicles using multi-omics profiling. RESULTS: Integrated analysis identified 81 differentially abundant proteins (DAPs) and 141 differentially abundant metabolites (DAMs) between the two groups. Functional enrichment analyses (GO/KEGG) demonstrated that DAPs are predominantly involved in intercellular signaling, apoptosis, and substance metabolism, while DAMs mainly participate in the metabolic and biosynthetic processes of various substances. Focusing on the apoptosis pathway --a key regulator of follicular growth --we validated that two pathway-associated proteins, tubulin α4a (TUBA4A) and tubulin α 1C (TUBA1C), exhibited expression patterns consistent with proteomic data. DISCUSSION: Our quantitative multi-omics findings define the molecular landscape underlying follicular size-dependent developmental differences, provide direct insights into the physiological status of follicular development, and offer actionable guidance for optimizing in vitro maturation (IVM) media for immature oocytes.