BAMBI modulates proliferation, apoptosis, and hormone secretion in Jinding duck granulosa cells

The BMP and activin membrane-bound inhibitor (BAMBI) gene is a pseudoreceptor involved in TGF-β signaling and plays an important role in follicular development. This study investigated the regulatory effects of BAMBI on the proliferation, apoptosis, and hormone secretion of follicular granulosa cells (GCs) in Jinding duck (Anas platyrhynchos domesticus). The recombinant plasmid duck BAMBI-pcDNA3.1 × 3Flag was successfully constructed, and both interference and overexpression systems were effectively expressed in GCs.EdU incorporation assays demonstrated that BAMBI interference significantly enhanced GC proliferation and upregulated the proliferating cell nuclear antigen (PCNA) expression, whereas BAMBI overexpression markedly inhibited proliferation and reduced PCNA mRNA and protein levels. Flow cytometry analysis showed that BAMBI interference decreased the apoptosis rate, while BAMBI overexpression increased it. Consistently, the expression of pro-apoptotic factors (Bax and Cleaved Caspase-3) was downregulated, and anti-apoptotic Bcl-2 was upregulated after BAMBI interference; the opposite trend occurred with BAMBI overexpression. ELISA and qRT-PCR analyses indicated that BAMBI interference significantly increased the levels of estradiol (E2) and prolactin (PRL), and upregulated the expression of their receptor genes ESR1, PRLR, and FSHR, while LHR expression was decreased. Conversely, BAMBI overexpression decreased E2 and PRL levels and induced opposite changes in receptor gene expression. In conclusion, BAMBI negatively regulates granulosa cell proliferation and is associated with reduced steroid hormone production while promoting apoptosis in Jinding duck granulosa cells in vitro. These findings provide new insights into the molecular mechanisms underlying follicular development and contribute to understanding the genetic regulation of reproductive traits in poultry.