Bone Morphogenetic Protein 6 Induces Downregulation of Pentraxin 3 Expression in Human Granulosa Cells through the SMAD-Dependent Signaling Pathway in Women with Polycystic Ovary Syndrome

Abstract Background: Pentraxin 3 contributes to the formation of cumulus-oophorus complex,its level is considered to indicate the quality and potential of oocytes. Bone morphogenetic protein 6 is a key regulator of ovary follicular development and regulates female reproduction. It is unclear whether Pentraxin 3 is differentially expressed in granulosa cells derived from Polycystic ovary syndrome and whether Bone morphogenetic protein 6 affects Pentraxin 3 in human granulosa-lutein cells.To evaluate whether Pentraxin 3 is differentially expressed in the granulosa cells derived from women with Polycystic Ovary Syndrome and whether granulosa cell-derived Bone Morphogenetic Protein 6 can regulate the expression of Pentraxin 3 in hGL cells. Materials and methods: The expression levels of BMP6 and PTX3 in granulosa cells were evaluated by RT-qPCR. The correlation between the expression levels of BMP6 and PTX3 and oocyte quality indexes were analyzed using clinical samples. The cells were incubated with BMP6 at different concentrations and times to check the expression of PTX3. TGF-β type 1 inhibitors and small interfering RNA targeting ALK2/3/6,SMAD1/5/8 and SMAD4 were used to study the involvement of SMAD dependent pathways. Results: The levels of Bone Morphogenetic Protein 6 in hGL cells were negatively correlated with the corresponding oocyte maturation rate and high-quality embryo rate, whereas the levels of Pentraxin 3 were positively correlated with the corresponding oocyte maturation rate in women with Polycystic Ovary Syndrome. Additionally, the in vitro cell cultured results showed Bone Morphogenetic Protein 6 significantly inhibited the expression of Pentraxin 3 in KGN cells. Furthermore, using a dual inhibition approach (kinase inhibitors and small interfering RNAs), we identified the ALK2/ALK3 type I receptors and BMPR2/ACVR2A type II receptors and the downstream SMAD1/SMAD5-SMAD4 signaling pathway were responsible for the BMP6-induced cellular activities in hGL cells. Conclusions: The suppressive effect of Bone Morphogenetic Protein 6 on Pentraxin 3 expression was mediated by ALK2/ALK3 type 1 receptors and BMPR2/ACVR2A type 2 receptors in granulosa cells through the SMAD1/5-SMAD4 dependent signaling pathway in women with Polycystic Ovary Syndrome.Our findings provides new insights into the understanding of the pathogenesis of Polycystic Ovary Syndrome-related ovulatory disorders.