Aim: The human endometrium is a dynamic tissue that undergoes regular cycles of menstruation, menstrual repair, proliferation and secretory differentiation in response to hypoxia and the female sex hormones. Methods: We identified new target genes that are regulated by progesterone during the decidualization of human endometrial stromal cells (ESC), including interleukin-15 (IL-15), fibulin-1 (FBLN-1), and heart and neural crest derivatives expressed transcript 2 (HAND2). Results: IL-15 is deeply involved in the hormonal control of the human endometrium by progesterone and may be important in embryo implantation. FBLN-1 has been shown to be an important extracellular matrix that mediates progesterone action in human ESC differentiation toward implantation. Moreover, progestininduced HAND2 is a transcription factor that contributes to the increased levels of FBLN-1 in human ESC. Several mediators, including vascular endothelial growth factor (VEGF), angiopoietin (ANGPT) and stromal cell-derived factor 1 (SDF-1), regulate human endometrial angiogenesis. Hypoxia increased the expression of VEGF and decreased the expression of SDF-1 in ESCs. Furthermore, hypoxia reduced ANGPT1 levels in ESC; however, ANGPT2 levels were unaffected. Estradiol simultaneously induced the expressions of VEGF and SDF-1, suppressing ANGPT1 production. Therefore, hypoxia and estradiol caused an increase in the ANGPT2/ANGPT1 ratio. Conclusion: Hypoxia and female sex hormones are involved in the regulation of angiogenic factors in an independent manner in human ESC. Analysis of the process of decidualization and angiogenesis in the human endometrium would provide useful information for the fields of reproductive biology, regenerative medicine and tissue engineering.
Hypoxia simultaneously acts to increase VEGF via HIF-1α and to decrease SDF-1 in a HIF-1α-independent manner in ESCs. These results indicate a potential mechanism for the action of hypoxic conditions that could influence angiogenesis in the human endometrium.
Purpose
Resveratrol is a well‐known potent activator of sirtuin‐1 (SIRT1). We investigated the direct effects of hypoxia and resveratrol on SIRT1/ peroxisome proliferator‐activated receptor‐gamma coactivator 1α (PGC‐1α) pathways, vascular endothelial growth factor (VEGF), hypoxia‐inducible factor (HIF)‐1α, and mitochondrial quantity in a steroidogenic human ovarian granulosa‐like tumor cell line (KGN) cells.
Methods
KGN cells were cultured with cobalt chloride (CoCl2; a hypoxia‐mimicking agent) and/or resveratrol. The mRNA and protein levels, protein secretion, and intracellular localization were assessed by real‐time PCR, Western blot analysis, ELISA, and immunofluorescence staining, respectively. Mitochondrial quantity was measured based on the mitochondrial DNA (mtDNA) copy number.
Results
CoCl2 simultaneously attenuated the levels of SIRT1 and mtDNA expression, and induced the levels of VEGF protein production. In contrast, resveratrol significantly increased the levels of SIRT1 and mtDNA copy number, but reduced VEGF production in normoxia. Resveratrol could recover CoCl2‐suppressed SIRT1 and mtDNA expression and antagonize CoCl2‐induced VEGF production. CoCl2 treatment resulted in a downregulation of PGC‐1α expression, and this effect was recovered by resveratrol. Resveratrol significantly suppressed the production of the CoCl2‐induced HIF‐1α and VEGF proteins.
Conclusion
These results suggest that resveratrol improves mitochondrial quantity by activating the SIRT1/PGC‐1α pathway and inhibits VEGF induction through HIF‐1α under hypoxic conditions.
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