(P02-032-23) Phthalate-Induced Clearance of Damaged Mitochondria in the Ovarian Granulosa Cell Layer via KIF5B/MYO19/DRP1 Pathway

Objectives: Phthalates are ubiquitous environmental contaminants that have been implicated in the global decline in female fertility. Among them, di-(2-ethylhexyl) phthalate (DEHP) is the most prevalently used. Mitochondrial quality control (MQC) is critical for maintaining mitochondrial homeostasis. The current evidence that showed the decreased mitochondrial quality of ovarian granulosa cell (GC), related to poor prognosis in female reproductive outcome. Nonetheless, the molecular mechanism by which DEHP exposure induces changes in the mode of MQC during ovarian GC layer is still unknown.

Methods: 8 days female quail were treated orally with DEHP (250, 500 and 750 mg/kg BW/day) for 45 days. H&E staining and ultrastructure observation were used to examine the morphological changes. Radioimmunoassay was conducted to assess the hormone levels. qRT-PCR, western blotting, and immunofluorescence staining were conducted to detect gene and protein levels. Molecular docking and PPI network analysis were used to validate the interaction.

Results: Histopathological assessment and ultrastructure observation found that DEHP decreased the thickness of GC layer, resulted in mitochondrial damage and activated mitocytosis. Furthermore, the findings also suggested that DEHP blocked the secretion of steroid hormones by activating mitocytosis, mitochondrial dynamics and mitophagy inducing GC function disorder. laterally, molecular docking results also revealed that the compound MEHP formed a strong hydrophobic interaction with the amino acids pro-17 and His-93 of the KIF5B protein pocket, which was significant for molecule stability. These results fully demonstrated that DEHP activated mitocytosis in GCs.

Conclusions: Overall, we determined that damaged mitochondrial not only eliminated by mitophagy but also by mitocytosis which resulted in the upregulation of KIF5B/MYO19/DRP1. Our research will provide an understanding of molecular mechanisms of GC layer proliferation in poultry, and future directions to provide a base for further GC layer growth and follicular development interaction in the ovaries.

Funding Sources: Joint Guidance Project of Natural Science Foundation of Heilongjiang Province of China (No. LH2021C045).
*Corresponding author: Dr. Xue-Nan Li. E-mail address: lixuenan@neau.edu.cn.