Dataset Information

The NADPH oxidase 4 is a major source of hydrogen peroxide in human granulosa-lutein and granulosa tumor cells.

ABSTRACT: H2O2 is a reactive oxygen species (ROS), which can diffuse away from its site of generation and may act as a cell-to-cell signaling factor. The mechanisms responsible for the generation of H2O2 in human ovarian follicles and possible signaling role(s) of H2O2 are not well known. We identified a source of H2O2, the enzyme NADPH oxidase (NOX) 4, in isolated differentiated, in-vitro fertilisation-derived human granulosa-lutein cells (GCs), in proliferating human granulosa tumour cells (KGN), as well as in situ in cells of growing ovarian follicles. H2O2 was readily detected in the supernatant of cultured GCs and KGN cells. H2O2 levels were significantly lowered by the NOX4 blocker GKT137831, indicating a pronounced contribution of NOX4 to overall H2O2 generation by these cells. We provide evidence that extracellular H2O2 is taken up by GCs, which is facilitated by aquaporins (peroxiporins). We thus conclude that GC-derived H2O2 might act as autocrine/paracrine factor. Addition of H2O2 increased MAPK-phosphorylation in GCs. Moreover, reducing H2O2 production with GKT137831 slowed proliferation of KGN cells. Our results pinpoint NOX4 and H2O2 as physiological players in the regulation of GC functions.

SUBMITTER: Buck T

PROVIDER: S-EPMC6400953 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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The NADPH oxidase 4 is a major source of hydrogen peroxide in human granulosa-lutein and granulosa tumor cells.

Buck Theresa T Hack Carsten Theo CT Berg Dieter D Berg Ulrike U Kunz Lars L Mayerhofer Artur A

Scientific reports 20190305 1

H2O2 is a reactive oxygen species (ROS), which can diffuse away from its site of generation and may act as a cell-to-cell signaling factor. The mechanisms responsible for the generation of H2O2 in human ovarian follicles and possible signaling role(s) of H2O2 are not well known. We identified a source of H2O2, the enzyme NADPH oxidase (NOX) 4, in isolated differentiated, in-vitro fertilisation-derived human g ...[more]

PMID: 30837663

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Project description:Aquaporin-8 (AQP8), a member of the aquaporin family, is strongly expressed in follicular granulosa cells, which could affect the hormone secretion level in females. AQP8, as a membrane protein, could mediate H2O2 into cells, thereby triggering various biological events. The deficiency of Aqp8 increases female fertility, resulting from the decrease in follicular atresia. The low cell death rate is related to the apoptosis of granulosa cells. However, the mechanism by which AQP8 regulates the autophagy of granulosa cells remains unclear. Thus, this study aimed to explore the effect of AQP8 on autophagy in follicular atresia. We found that the expression of the autophagy marker light-chain protein 3 was significantly downregulated in the granulosa cells of Aqp8-knockout (Aqp8 -/- ) mice, compared with wild-type (Aqp8 +/+ ) mice. Immunofluorescence staining and transmission electron microscopic examination indicated that the number of autophagosomes in the granulosa cells of Aqp8 -/- mice decreased. Using a follicular granulosa cell autophagy model, namely a follicular atresia model, we verified that the concentration of H2O2 significantly increased during the autophagy of granulosa cells, consistent with the Aqp8 mRNA level. Intracellular H2O2 accumulation was modulated by endogenous AQP8 expression level, indicating that AQP8-mediated H2O2 was involved in the autophagy of granulosa cells. AQP8 deficiency impaired the elevation of H2O2 concentration through phosphorylated tyrosine activation. In addition, we carried out the analysis of transcriptome sequencing datasets in the ovary and found there were obvious differences in principal components, differentially expressed genes (DEGs) and KEGG pathways, which might be involved in AQP8-regulated follicular atresia. Taken together, these findings indicated that AQP8-mediated H2O2 transport could mediate the autophagy of granulosa cells. AQP8 might be a potential target for diseases related to ovarian insufficiency.

Project description:RationaleHydrogen peroxide (H2O2) is a stable reactive oxygen species (ROS) that has long been implicated in insulin signal transduction in adipocytes. However, H2O2's role in mediating insulin's effects on the heart are unknown.ObjectiveWe investigated the role of H2O2 in activating insulin-dependent changes in cardiac myocyte metabolic and inotropic pathways. The sources of insulin-dependent H2O2 generation were also studied.Methods and resultsIn addition to the canonical role of insulin in modulating cardiac metabolic pathways, we found that insulin also inhibited beta adrenergic-induced increases in cardiac contractility. Catalase and NADPH oxidase (NOX) inhibitors blunted activation of insulin-responsive kinases Akt and mTOR and attenuated beta adrenergic receptor-mediated responses. These insulin responses were lost in a mouse model of type 2 diabetes, suggesting a role for these H2O2-dependent pathways in the diabetic heart. The H2O2-sensitive fluorescent biosensor HyPer revealed rapid increases in cytosolic and caveolar H2O2 concentrations in response to insulin treatment, which were blocked by NOX inhibitors and attenuated in NOX2 KO and NOX4 KO mice. In NOX2 KO cardiac myocytes, insulin-mediated phosphorylation of Akt and mTOR was blocked, while these responses were unaffected in cardiac myocytes from NOX4 KO mice. In contrast, insulin's effects on contractility were lost in cardiac myocytes from NOX4 KO animals but were retained in NOX2 KO mice.ConclusionsThese studies identify a proximal point of bifurcation in cardiac insulin signaling through the simultaneous activation of both NOX2 and NOX4. Each NOX isoform generates H2O2 in cardiac myocytes with distinct time courses, with H2O2 derived from NOX2 augmenting Akt-dependent metabolic effects of insulin, while H2O2 from NOX4 blocks beta adrenergic increases in inotropy. These findings suggest that insulin resistance in the diabetic heart may lead to potentially deleterious potentiation of beta adrenergic responses.

Dataset Information

The NADPH oxidase 4 is a major source of hydrogen peroxide in human granulosa-lutein and granulosa tumor cells.

Publications

The NADPH oxidase 4 is a major source of hydrogen peroxide in human granulosa-lutein and granulosa tumor cells.

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