Overexpression of hypoxia-inducible factor prolyl hydoxylase-2 attenuates hypoxia-induced vascular endothelial growth factor expression in luteal cells

Pan

et al. 2015

Mol Med Report

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Abstract. Vascular endothelial growth factor (VEGF) is vital in normal and abnormal angiogenesis in the ovary, particularly during the early development of the corpus luteum in the ovary. However, the molecular regulation of the expression VEGF during luteal development in vivo remains to be fully elucidated. As the expression of VEGF is mediated by hypoxia-inducible factor (HIF)-1α in luteal cells cultured in vitro, determined in our previous study, the present study was performed to confirm the hypothesis that HIF-1α is induced and then regulates the expression of VEGF and VEGF-dependent luteal development/function in vivo. This was investigated using a pregnant rat model treated with a small-molecule inhibitor of HIF-1α, echinomycin (Ech). The development of the corpus luteum in the pregnant rat ovary was identified via performing assays of the serum progesterone, testosterone and estradiol concentrations by radioimmunoassay, accompanied with determination of the changes in the expression levels of HIF-1α and VEGF by reverse transcription-quantitative polymerase chain reaction at different days of the developmental process. On day 5, serum progesterone levels were markedly increased, whereas serum levels of testosterone and estradiol did not change significantly. On day 17, the highest level of serum progesterone was observed, however, this was not the case for testosterone and estradiol. Further analysis of the expression levels of HIF-1α and VEGF revealed that their changes were consistent with the changes in serum levels of progesterone, which occurred in the development of the corpus luteum in the ovaries of pregnant rats. Further investigation demonstrated that Ech inhibited luteal development through inhibiting the expression of VEGF, mediated by HIF-1α, and subsequent luteal function, which was determined by detecting changes in serum progesterone on days 8 and 14. Taken together, these results demonstrated that HIF-1α-mediated expression of VEGF may be one of the important mechanisms regulating ovarian luteal development in mammals in vivo, which may provide novel strategies in treatment for fertility control and for certain types of ovarian dysfunction, including polycystic ovarian syndrome, ovarian hyperstimulation syndrome and ovarian neoplasia.

Section: Rna Extraction and Reverse Transcription-quantitative Polymementioning

confidence: 99%

Expression and contribution of the HIF‑1α/VEGF signaling pathway to luteal development and function in pregnant rats

Pan

et al. 2015

Mol Med Report

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“…In the ovary, VEGF is an important endocrine factor and involved in the normal and abnormal angiogenesis, especially in the newly formed corpus luteum (Fraser et al, ; Kaczmarek et al, ; Duncan et al, ; Zhang et al, , b, ; Kwik and Maxwell, ; Woad and Robinson, ; Jellad et al, ; Rizov et al, ). The follicles were ruptured after ovulation and the hypoxia was caused by accompanied bleeding and immature vasculatures (Nishimura and Okuda, ).…”

Section: Discussionmentioning

confidence: 99%

“…Rat luteal cells were isolated and cultured as methods described previously (Zhang et al, ). The cells were examined by Trypan blue dye and hemocytometer counting, and then cultured in six‐well plates with the concentration of 10 6 cells per mL for the following experimental treatments.…”

Section: Methodsmentioning

confidence: 99%

“…Our previous studies have demonstrated human chorionic gonadotrophin (HCG) induced VEGF mRNA expression through the activation of hypoxia‐inducible factor (HIF)‐1α transcription in luteal cells even under normoxic condition (Zhang et al, , b, ). Notably, some studies have indicated there was a closely crosstalk between HIF‐1α and nuclear factor (NF)‐κB signaling pathway (Belaiba et al, ; Rius et al, ; van Uden et al, ), since NF‐κB may interact with HIF‐1α through binding to NF‐κB binding sites of the HIF‐1α promoter (van Uden et al, ) and regulate HIF‐1α expression induced by tumor necrosis factor‐alpha (Belaiba et al, ; Rius et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Activation of NF‐κB signaling pathway during HCG‐induced VEGF expression in luteal cells

Huang

Cell Biology International

et al. 2019

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Vascular endothelial growth factor (VEGF) plays an essential role in luteal angiogenesis, the present study therefore utilized luteal cells cultured in vitro to further investigate the activation and contribution of nuclear factor (NF)‐κB to VEGF expression induced by human chorionic gonadotrophin (HCG). The present results showed HCG induced VEGF expression as well as hypoxia‐inducible factor (HIF)‐1α mRNA and protein expressions, which was blocked by NF‐κB inhibitor pyrrolidine dithiocarbamate (PDTC). Further analysis found that these increases of VEGF and HIF‐1α mRNA induced by HCG were also blocked by NF‐κB siRNA transfection, which was consistent with PDTC treatment. However, HIF‐1α siRNA treatment significantly decreased HCG induced‐VEGF expression with no effect on NF‐κB mRNA expression. Furthermore, combination of HIF‐1α siRNA and PDTC treatment did not further decrease VEGF mRNA expression, and the result of chromatin immunoprecipitation indicated NF‐κB may regulate HIF‐1α transcription through binding with its promoter. Taken together, the present results clearly demonstrated that NF‐κB was activated to regulate VEGF expression by increasing HIF‐1α transcription in luteal cells treated with HCG. Therefore, the present study provided a new and important mechanism of luteal angiogenesis during the formation of corpus luteum in mammals.

“…Immunoblotting was performed as previously described (2,(29)(30)(31)(32)(33)(34). Briefly, ovaries from different experimental groups were sonicated in lysis buffer containing a protease inhibitor cocktail (Sigma-Aldrich, St. Louis, MO, USA).…”

Section: Methodsmentioning

confidence: 99%

Effect of high-fat diet-induced obesity on the Akt/FoxO/Smad signaling pathway and the follicular development of the mouse ovary

Molecular Medicine Reports

Liao

et al. 2016

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Abstract. Obesity has a negative effect on ovarian functions, which is reported to increase the risk of infertility. The mechanism underlying obesity-induced infertility is not yet clear. The present study established a high-fat diet (HFD)-induced obesity mouse model to elucidate the mechanisms underlying the effect of HFD-induced obesity on follicular development in the mouse ovary. The 4-week-old female mice were fed with HFD or normal control (NC) diet for 15 or 20 weeks. Body mass index was used to demonstrate that the mice were obese following HFD treatment. The follicular development of the ovaries from the HFD group mice was retarded in a time-dependent manner, as demonstrated by morphological and histological examination of the ovaries. Further investigation via western blot analysis demonstrated that the activity of the transcription factor, forkhead box O3a (FoxO3a), was increased by HFD through downregulated FoxO3a phosphorylation, which may contribute to the inhibited development of ovarian follicles. To determine the regulatory mechanism of FoxO3 on the follicular development, the expression levels of FoxO3a target protein, Smad1/5/8, were also determined and there was significant decrease in phosphorylated Smad1/5/8 in the ovaries from the HFD group compared with the NC group, indicating that FoxO3a/Smad1/5/8 may be important in the regulation of follicular development. The expression levels of the upstream regulator of FoxO3a, Akt, were also examined and it was demonstrated that Akt phosphorylation was significantly reduced in the HFD group compared with the NC group, indicating that Akt/FoxO3a may be also involved in follicular development. Together, the experiments demonstrated that HFD-induced obesity affected the activity of the Akt/FoxO3a/Smad1/5/8 signaling pathway in a time-dependent manner during the follicular development of the mouse ovary, leading to abnormal follicular development. These findings may provide part of a theoretical basis for the clinical prevention and treatment of obesity-associated female infertility.