Knockdown of DPP4 promotes the proliferation and the activation of the CREB/aromatase pathway in ovarian granulosa cells

Abstract

Dipeptidyl peptidase 4 (DPP4) has been revealed to be upregulated in women suffering from polycystic ovary syndrome (PCOS), which is a common reproductive disorder. The present study was designed to investigate the effects of inhibition of DPP4 expression on the proliferation of ovarian granulosa cells as well as on the activation of the cAMP response element-binding protein (CREB)/aromatase pathway. The expression levels of DPP4 in rat serum samples with or without PCOS and ovarian granulosa cells (KGN cells) were detected using reverse transcription-quantitative PCR (RT-qPCR) and western blot analyses. Cell viability and cell cycle progression were detected using the Cell Counting Kit-8 assay and flow cytometric analysis, respectively. The 5-ethynyl-2'-deoxyuridine assay was employed to detect the proliferation of glycolaldehyde-bovine serum albumin (GOA-BSA)-treated KGN cells. In addition, RT-qPCR and western blot analyses were applied to detect the expression levels of CREB, specific cell cycle-associated proteins and cytochrome P450 (CYP) 19A1 and CYP11A1 enzymes in KGN cells. The expression levels of DPP4 were upregulated in rats with PCOS. Inhibition of DPP4 expression promoted the proliferation and cell cycle arrest of KGN cells. It was also revealed that the expression levels of cell cycle-associated proteins were upregulated in DPP4-silenced KGN cells. In addition, their proliferation was decreased following treatment with GOA-BSA, while the addition of sitagliptin partially reversed these effects. Additionally, sitagliptin reversed the inhibitory effects caused by GOA-BSA treatment on the cell cycle progression and on the activation of the CREB/aromatase pathway in KGN cells, as determined by the increased expression levels of the cell cycle-associated proteins as well as those of the CREB protein and the CYP19A1 and CYP11A1 enzymes. In conclusion, inhibition of DPP4 expression promoted the proliferation of KGN cells and the activation of the CREB/aromatase pathway.

Farnesyl Diphosphate Synthase (FDPS) Regulates Granulosa Cells Proliferation of Polycystic Ovary Syndrome (PCOS) by Modulating the Rac1/MAPK/ERK signaling

“…Follicular dysplasia and ovulation disorder are the main causes of infertility of PCOS, which are associated with abnormal proliferation of GCs, inhibition of GC proliferation leaded to nutrient and communication de ciencies in oocyte development [7,25]. Some scholars have reported that DPP4 knockout promotes proliferation and activation of CREB/ aromatase pathway in GCs, thereby alleviating PCOS [39]. Recent accumulated evidence revealed that FDPS has been found to be involved in various biological functions and disease processes, such as FDPS regulates endothelial cell proliferation and autophagy [13].…”

Effects of Yinzhihuang on Alleviating Cyclosporine A-Induced Cholestatic Liver Injury <i>via</i> Farnesoid X Receptor-Mediated Regulation of Transporters and Enzymes <i>in Vitro</i> and <i>in Vivo</i>

“…Following anaesthetization with intraperitoneal injection of 2% pentobarbital sodium (40 mg•kg −1 ), the rat abdomen was opened, and blood samples 2-3 mL were obtained from the abdominal aorta. 30) Then, the liver tissue was dissected out for biochemical analysis. Finally, the unconscious rats were immediately decapitated.…”