Effect of VEGF on the expression of genes related to ovarian steroid synthesis in mice and its mechanism
Objective To investigate the effect of vascular endothelial growth factor(VEGF)on the expression of genes related to ovarian steroid synthesis in mice and its underlying mechanism.Methods A transgenic mouse model with tetracycline-reversible regulation of VEGF expression was used,and the genotype of mice was identified by polymerase chain reaction(PCR).Twenty mice were divided into normal VEGF expression group(Dox+,n=10)and VEGF expression inhibition group(Dox-,n=10)by feeding them doxycycline.Western blotting was used to detect the expression of VEGF protein in ovarian tissues.Fluorescence quantitative PCR was used to detect the mRNA expression of VEGF,KDR and genes known to play roles in follicle development,such as follicle-stimulating hormone(FSH)and inhibin B(INHBB).HE staining was used to observe changes in ovarian tissue.Total RNA was extracted from mouse ovarian tissues for transcriptome sequencing,and the relevant differential genes were analyzed by FPKM and log2FC values.Results Compared with the Dox+group,the mRNA and protein levels of VEGF in the Dox-group significantly reduced,and the mRNA levels of KDR also significantly decreased(P<0.05).HE staining results showed that compared with the Dox+group,follicular development was impaired and atresia follicles appeared in the Dox-group.Sequencing analysis identified that significant differences in follicular development-related genes and steroid synthesis-related genes between the two groups(P<0.05).Enrichment analysis showed that VEGF in mouse ovaries mainly regulates ovarian steroidogenesis and other pathways.Fluorescence quantitative PCR results demonstrated that compared with the Dox+group,the follicular development-related genes(INHBB and FSHR)in the ovarian tissues of the Dox-group were significantly up-regulated(P<0.05),whereas the key genes of steroid synthesis(StAR,CYP11A1,3β-HSD)were significantly down-regulated(P<0.05).The quantitative results were basically consistent with the sequencing results.Conclusion Mice with inhibited VEGF exhibited ovarian follicular dysplasia,potentially due to the mechanism whereby VEGF inhibition downregulated the expression of genes associated with steroid synthesis,such as FSH and INHBB,thereby obstructing cholesterol metabolism.