DBP Exposure Affects Oocyte Fertilization Via Extracellular Vesicles-Derived miR-116-5p in Ovarian Granulosa Cells Through Downregulating FOXO3a Expression

Mono-butyl phthalate (MBP), the metabolite of dibutyl phthalate (DBP), is the most abundant phthalate metabolite found in Chinese women. Extracellular vesicles (EVs) are nanoscale lipid bilayer particles produced by extensive kinds of cells, serving a key role in intercellular communication. Extracellular vesicle miRNAs (EV-miRNAs) in follicular fluid (FF) have been evidenced to be associated with female reproductive health. The objective of this study was to investigate the associations of EV-miRNAs expressed profile with DBP exposure in FF of female participants and expose its potential mechanism in impaired oocyte development. Based on participants' FF MBP concentrations and fertilization status, we compared the miRNA expression between the FF-EVs of group A (high DBP exposure and impaired fertilization) and group B (low DBP exposure and normal fertilization). Compared with group B, miR-1246, miR-3679-5p, miR-423-5p, miR-5585-3p, miR-116-5p, miR-172-5p were upregulated, while miR-34b-3p was downregulated in group A. Target genes of the differently expressed miRNAs were predicted, and the functional analysis was performed. Furthermore, we exposed human ovarian granulosa tumor cell line (KGN) to MBP (4ug/L) to isolate the EVs from the culture medium and validated the expression levels of different miRNAs. We found that MBP exposure was significantly associated with increased levels of miR-116-5p (P = 0.01). In addition, we demonstrated that the most different miRNA, miR-116-5p regulated oocyte fertilization by inhibiting FOXO3a. Our findings suggested that EV-miRNAs in the FF might mediate MBP toxicity in oocytes.

Extracellular vesicle; Follicular fluid; MicroRNA; Oocyte; Phthalate.