Erbb4 regulates the oocyte microenvironment during folliculogenesis

Area of Science:

• Reproductive Endocrinology
• Molecular Biology
• Genetics

Background:

• Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting fertility, endocrine, and metabolic systems.
• A single nucleotide polymorphism (SNP) in the ERBB4 gene is linked to PCOS, but its ovarian function is unclear.
• Existing animal models do not fully replicate PCOS reproductive features.

Purpose of the Study:

• To investigate the role of ERBB4 in ovarian granulosa cells (GCs) during folliculogenesis.
• To elucidate the impact of ERBB4 deletion on ovarian function and PCOS-like phenotypes.
• To understand the molecular mechanisms linking ERBB4 to ovarian pathophysiology.

Main Methods:

• Conditional deletion of Erbb4 in murine GCs using the Amh promoter.
• Assessment of reproductive and metabolic functions, including estrous cycles, ovulation, and obesity.
• Hormonal analysis (luteinizing hormone, androgens, anti-Müllerian hormone).
• In vitro knockdown of Erbb4 using shRNAs in GC cultures.

Main Results:

• Erbb4 deletion in GCs caused asynchronous estrous cycles, reduced ovulation, subfertility, and obesity.
• Ovaries exhibited structural and functional abnormalities, including impaired oocyte development.
• Elevated serum luteinizing hormone, hyperandrogenism, and increased anti-Müllerian hormone levels were observed.
• Defective intercellular junctions between GCs and oocytes were identified, altering follicular microenvironment gene expression.
• Erbb4 is essential for regulating Amh levels, confirmed by in vitro assays.

Conclusions:

• ERBB4 plays a crucial role in ovarian function, particularly during folliculogenesis.
• Reduced ERBB4 expression in GCs contributes to reproductive pathophysiology, including PCOS development.
• ERBB4 signaling is vital for maintaining GC-oocyte communication and follicular development.