Involvement of JNK/FOXO1 pathway in apoptosis induced by severe hypoxia in porcine granulosa cells

Deletion of the foxO1 gene reduces hypoxia tolerance in zebrafish embryos by influencing erythropoiesis

FoxO1 (Forkhead box O1) belongs to the evolutionarily conserved FoxO subfamily and is involved in diverse physiologic processes, including apoptosis, cell cycle, DNA damage repair, oxidative stress and cell differentiation. FoxO1 plays an important role in regulating the hypoxia microenvironment such as cancers, but its role in hypoxia adaptation remains unclear in animals. To understand the function of foxO1 in hypoxia response, we constructed foxO1a and foxO1b mutant zebrafish using CRISPR/Cas9 technology. It was found that foxO1a and foxO1b destruction affected the hematopoietic system in the early zebrafish embryos. Specifically, FoxO1a and FoxO1b were found to affect the transcriptional activity of runx1, a marker gene for hematopoietic stem cells (HSCs). Moreover, foxO1a and foxO1b had complementary features in hypoxia response, and foxO1a or/and foxO1b destruction resulted in tolerance of zebrafish becoming weakened in hypoxia due to insufficient hemoglobin supply. Additionally, the transcriptional activity of these two genes was demonstrated to be regulated by Hif1α. In conclusion, foxO1a and foxO1b respond to Hif1α-mediated hypoxia response by participating in zebrafish erythropoiesis. These results will provide a theoretical basis for further exploring the function of FoxO1 in hematopoiesis and hypoxia response.

Pivotal role of JNK protein in the therapeutic efficacy of parthenolide against breast cancer: Novel and comprehensive evidences from network pharmacology, single-cell RNA sequencing and metabolomics

This study aimed to evaluate the efficacy and therapeutic mechanism of parthenolide (PTL) in breast cancer (BC) through a comprehensive strategy integrating network pharmacology, single-cell RNA sequencing (scRNA-seq) and metabolomics. In network pharmacology, 70 therapeutic targets were identified, of which 16 core targets were filtered out through seven classical algorithms of Cytohubba plugin. Additionally, the hub module of PPI network was extracted using MCODE plugin. Molecular docking and molecular dynamics simulation showed a potent binding affinity between PTL and JNK, subsequently validated by MST and SPR assays. Further, Mendelian randomization analysis indicated that JNK was causally associated with BC. GO and KEGG enrichment analyses revealed that PTL counteracted BC via promoting ROS generation, inducing apoptosis and suppressing proliferation, which potentially involved the coordinated regulation of MAPK and FoxO1 pathways. Moreover, ssGSEA and scRNA-seq analysis suggested that PTL may act on T cell immune microenvironment of BC. Subsequently, these bioinformatics-based predictions were experimentally validated using in-vitro and in-vivo models. Finally, metabolome profiling unveiled that PTL remodeled the glycine, serine and threonine metabolism as well as biosynthesis of unsaturated fatty acids, and thereby contributed to BC inhibition. From molecular, immune and metabolic perspectives, this study not only provided a unique insight into the mechanistic details of PTL against BC, but also proposed a novel promising therapeutic strategy for BC.

Lactylation drives hCG-triggered luteinization in hypoxic granulosa cells

Hypoxia that occurs during the luteinization process of granulosa cells (GC) contributes to the formation of lactate in follicles. Lysine lactylation (Kla), a post-translational modification directly regulated by lactate levels, is a metabolic sensor that converts metabolic information into gene expression patterns. In this study, we employed human chorionic gonadotropin (hCG) to induce GCs luteinization and discovered that hypoxia enhances hCG-mediated GCs luteinization by stimulating lactate production/lactylation. The elevated levels of luteinization markers (including progesterone synthesis, expression of CYP11A1 and STAR) were accompanied by increased lactate production as well as enhanced lactylation in mouse ovarian GCs after the injection of hCG in vivo. By treating GCs with hypoxia in vitro, we found that hypoxia accelerated hCG-induced GCs luteinization, which was inhibited after blocking lactate production/lactylation. Further investigations revealed that H3K18la might contribute to hCG-induced luteinization in hypoxic GCs by upregulating CYP11A1 and STAR transcription. Additionally, we identified that CREB K136la is also required for hCG-induced GCs luteinization under hypoxia. Finally, the in vitro findings were verified in vivo, which showed impaired GCs luteinization and corpus luteum formation after blocking the lactate/lactylation by intraperitoneal injection of oxamate/C646 in mice. Taken together, this study uncovered a novel role of protein lactylation in the regulation of GCs luteinization.

Research progress on reproductive system damage caused by high altitude hypoxia

PURPOSE

The high altitude area is characterized by low pressure and hypoxia, and rapidly entering the high altitude area will cause a series of damage to the body. Some studies have shown that hypoxia can cause damage to the reproductive system. In recent years, researchers have been paying attention to the effects of hypoxia on hormone level, ovarian reserve, embryonic development, testicular development, sperm motility level, and have begun to explore its injury mechanism, but its mechanism is not clear. In this paper, the mechanism of hypoxia on the reproductive system is reviewed, which is expected to provide a new idea for solving the problem of the low fertility rate of humans and animals at high altitudes.

METHODS

A comprehensive PubMed search was conducted, selecting all relevant peer-reviewed English papers published before January 2022. Other relevant papers were selected from the list of references.

RESULTS

Studies have shown that the complete fertility rate of people living at low altitudes is 7.7, and the complete fertility rate of people living at high altitudes is 4.77, and the hypoxic environment at high altitudes reduces fertility. At the same time, high-altitude, low-oxygen environments are associated with increased infant mortality and post-neonatal mortality. To date, most studies seem to point to a correlation between anoxic exposure at high altitudes and low fertility in humans and animals.

CONCLUSION

Although the molecular mechanisms are not fully understood, the effects of hypoxia at high altitude on hormonal level, ovarian reserve, embryonic development, testicular development, and sperm motility and levels require further research to investigate this complex topic.

FSH preserves the viability of hypoxic granulosa cells via activating the HIF-1α-GAS6-Axl-Akt pathway

The developmental fate of ovarian follicles is primarily determined by the survival status (proliferation or apoptosis) of granulosa cells (GCs). Owing to the avascular environment within follicles, GCs are believed to live in a hypoxic niche. Follicle-stimulating hormone (FSH) has been reported to improve GCs survival by governing hypoxia-inducible factor-1α (HIF-1α)-dependent hypoxia response, but the underlying mechanisms remain poorly understood. Growth arrest-specific gene 6 (GAS6) is a secreted ligand of tyrosine kinase receptors, and has been documented to facilitate tumor growth. Here, we showed that the level of GAS6 was markedly increased in mouse ovarian GCs after the injection of FSH. Specifically, FSH-induced GAS6 expression was accompanied by HIF-1α accumulation under conditions of hypoxia both in vivo and in vitro, whereas inhibition of HIF-1α with small interfering RNAs/antagonist repressed both expression and secretion of GAS6. As such, Luciferase reporter assay and chromatin immunoprecipitation assay showed that HIF-1α directly bound to a hypoxia response element site within the Gas6 promoter and contributed to the regulation of GAS6 expression in response to FSH. Notably, blockage of GAS6 and/or its receptor Axl abrogated the pro-survival effects of FSH under hypoxia. Moreover, phosphorylation of Axl by GAS6 is required for FSH-mediated Akt activation and the resultant pro-survival phenotypes. Finally, the in vitro findings were verified in vivo, which showed that FSH-induced proliferative and antiapoptotic effects in ovarian GCs were diminished after blocking GAS6/Axl using HIF-1α antagonist. These findings highlight a novel function of FSH in preserving GCs viability against hypoxic stress by activating the HIF-1a-GAS6-Axl-Akt pathway.

Follicular fluid meiosis-activating sterol prevents porcine ovarian granulosa cells from hypoxia-induced apoptosis via inhibiting STAT4 expression

Follicular fluid meiosis-activating sterol (FF-MAS) is a small molecule compound found in FF, named for its ability to induce oocyte resumption of meiosis. Granulosa cells (GCs) within the follicle are typically located in a hypoxic environment under physiologic conditions due to limited vascular distribution. Previous research suggests that hypoxia-induced cell cycle arrest and apoptosis in GCs may be crucial triggering factors in porcine follicular atresia. However, the impact of FF-MAS on GCs within follicles has not been explored so far. In this study, we uncovered a novel role of FF-MAS in facilitating GC survival under hypoxic conditions by inhibiting STAT4 expression. We found that STAT4 expression was upregulated in porcine GCs exposed to 1% O2. Both gain and loss of function assays confirmed that STAT4 was required for cell apoptosis under hypoxia conditions, and that the GC apoptosis caused by hypoxia was markedly attenuated following FF-MAS treatment through inhibition of STAT4 expression. Correlation analysis in vivo revealed that GC apoptosis was associated with increased STAT4 expression, while the FF-MAS content in follicular fluid was negatively correlated with STAT4 mRNA levels and cell apoptosis. These findings elucidate a novel role of FF-MAS-mediated protection of GCs by inhibiting STAT4 expression under hypoxia, which might contribute to the mechanistic understanding of follicular development.

IGF-I protects porcine granulosa cells from hypoxia-induced apoptosis by promoting homologous recombination repair through the PI3K/AKT/E2F8/RAD51 pathway

Severe hypoxia induced by vascular compromise (ovarian torsion, surgery), obliteration of vessels (aging, chemotherapy, particularly platinum drugs) can cause massive follicle atresia. On the other hand, hypoxia increases the occurrence of DNA double-strand breaks (DSBs) and triggers cellular damage repair mechanisms; however, if the damage is not promptly repaired, it can also induce the apoptosis program. Insulin-like growth factor-I (IGF-I) is a polypeptide hormone that plays essential roles in stimulating mammalian follicular development. Here, we report a novel role for IGF-I in protecting hypoxic GCs from apoptosis by promoting DNA repair through the homologous recombination (HR) process. Indeed, the hypoxic environment within follicles significantly inhibited the efficiency of HR-directed DNA repair. The presence of IGF-I-induced HR pathway to alleviate hypoxia-induced DNA damage and apoptosis primarily through upregulating the expression of the RAD51 recombinase. Importantly, we identified a new transcriptional regulator of RAD51, namely E2F8, which mediates the protective effects of IGF-I on hypoxic GCs by facilitating the transcriptional activation of RAD51. Furthermore, we demonstrated that the PI3K/AKT pathway is crucial for IGF-I-induced E2F8 expression, resulting in increased RAD51 expression and enhanced HR activity, which mitigates hypoxia-induced DNA damage and thereby protects against GCs apoptosis. Together, these findings define a novel mechanism of IGF-I-mediated GCs protection by activating the HR repair through the PI3K/AKT/E2F8/RAD51 pathway under hypoxia.

Single-cell transcriptomic atlas of goat ovarian aging

BACKGROUND

The ovaries are one of the first organs that undergo degenerative changes earlier in the aging process, and ovarian aging is shown by a decrease in the number and quality of oocytes. However, little is known about the molecular mechanisms of female age-related fertility decline in different types of ovarian cells during aging, especially in goats. Therefore, the aim of this study was to reveal the mechanisms driving ovarian aging in goats at single-cell resolution.

RESULTS

For the first time, we surveyed the single-cell transcriptomic landscape of over 27,000 ovarian cells from newborn, young and aging goats, and identified nine ovarian cell types with distinct gene-expression signatures. Functional enrichment analysis showed that ovarian cell types were involved in their own unique biological processes, such as Wnt beta-catenin signalling was enriched in germ cells, whereas ovarian steroidogenesis was enriched in granulosa cells (GCs). Further analysis showed that ovarian aging was linked to GCs-specific changes in the antioxidant system, oxidative phosphorylation, and apoptosis. Subsequently, we identified a series of dynamic genes, such as AMH, CRABP2, THBS1 and TIMP1, which determined the fate of GCs. Additionally, FOXO1, SOX4, and HIF1A were identified as significant regulons that instructed the differentiation of GCs in a distinct manner during ovarian aging.

CONCLUSIONS

This study revealed a comprehensive aging-associated transcriptomic atlas characterizing the cell type-specific mechanisms during ovarian aging at the single-cell level and offers new diagnostic biomarkers and potential therapeutic targets for age-related goat ovarian diseases.

The chromatin remodeling protein BPTF mediates cell cycle, proliferation and apoptosis in porcine ovarian granulosa cells

Bromodomain PHD finger transcription factor (BPTF), a core subunit of nucleosome-remodeling factor (NURF) complex, plays an important role in chromatin remodeling. However, few information of BPTF is available in pig, especially in mammalian follicular granulosa cells (GCs). The present study firstly confirmed that BPTF in porcine was relative close to human and mouse. The expression of BPTF could be detected in ovary, testes, lung, kidney, large intestine, and small intestine. And a relative high expression of BPTF was observed in ovarian follicles and GCs. When BPTF was knocked down (BPTF-siRNA), the viability of GCs was affected. And the expression level of CDK1, cyclin B1, CDK4 and CDK2 was higher than the control, which might indicate that the cell cycle of GCs was inhibited from S to G2/M phase. Although the apoptosis level was induced in the BPTF-siRNA GCs, the reduced level of H3K4 methylation was detected with the down regulation of SMYD3, EHMT2 and DPY30. Thereby, results in the present might provide the primary knowledge of BPTF in GCs and the follicular development in pig.

Decreased HAT1 expression in granulosa cells disturbs oocyte meiosis during mouse ovarian aging

BACKGROUND

With advanced maternal age, abnormalities during oocyte meiosis increase significantly. Aneuploidy is an important reason for the reduction in the quality of aged oocytes. However, the molecular mechanism of aneuploidy in aged oocytes is far from understood. Histone acetyltransferase 1 (HAT1) has been reported to be essential for mammalian development and genome stability, and involved in multiple organ aging. Whether HAT1 is involved in ovarian aging and the detailed mechanisms remain to be elucidated.

METHODS

The level of HAT1 in aged mice ovaries was detected by immunohistochemical and immunoblotting. To explore the function of HAT1 in the process of mouse oocyte maturation, we used Anacardic Acid (AA) and small interfering RNAs (siRNA) to culture cumulus-oocyte complexes (COCs) from ICR female mice in vitro and gathered statistics of germinal vesicle breakdown (GVBD), the first polar body extrusion (PBE), meiotic defects, aneuploidy, 2-cell embryos formation, and blastocyst formation rate. Moreover, the human granulosa cell (GC)-like line KGN cells were used to investigate the mechanisms of HAT1 in this progress.

RESULTS

HAT1 was highly expressed in ovarian granulosa cells (GCs) from young mice and the expression of HAT1 was significantly decreased in aged GCs. AA and siRNAs mediated inhibition of HAT1 in GCs decreased the PBE rate, and increased meiotic defects and aneuploidy in oocytes. Further studies showed that HAT1 could acetylate Forkhead box transcription factor O1 (FoxO1), leading to the translocation of FoxO1 into the nucleus. Resultantly, the translocation of acetylated FoxO1 increased the expression of amphiregulin (AREG) in GCs, which plays a significant role in oocyte meiosis.

CONCLUSION

The present study suggests that decreased expression of HAT1 in GCs is a potential reason corresponding to oocyte age-related meiotic defects and provides a potential therapeutic target for clinical intervention to reduce aneuploid oocytes.

Melatonin-Mediated Suppression of mtROS-JNK-FOXO1 Pathway Alleviates Hypoxia-Induced Apoptosis in Porcine Granulosa Cells

Numerous studies have established that the hypoxic conditions within ovarian follicles induce apoptosis in granulosa cells (GCs), a pivotal hallmark of follicular atresia. Melatonin (N-acetyl-5-methoxytryptamine, MT), a versatile antioxidant naturally present in follicular fluid, acts as a safeguard for maintaining GCs' survival during stress exposure. In this study, we unveil an innovative protective mechanism of melatonin against hypoxia-triggered GC apoptosis by selectively inhibiting mitochondrial ROS (mtROS) generation. Specifically, under hypoxic conditions, a gradual accumulation of mitochondrial ROS occurred, consequently activating the JNK-FOXO1 pathway, and driving GCs toward apoptosis. The blocking of JNK or FOXO1 diminished hypoxia-induced GC apoptosis, but this effect was nullified in the presence of GSH, indicating that mtROS instigates apoptosis through the JNK-FOXO1 pathway. Consistent with this, hypoxic GCs treated with melatonin exhibited decreased levels of mtROS, reduced JNK-FOXO1 activation, and mitigated apoptosis. However, the protective capabilities of melatonin were attenuated upon inhibiting its receptor MTNR1B, accompanied by the decreased expression of antioxidant genes. Notably, SOD2, a key mitochondrial antioxidant gene modulated by the melatonin-MTNR1B axis, effectively inhibited the activation of mtROS-JNK-FOXO1 and subsequent apoptosis, whereas SOD2 knockdown abrogated the protective role of melatonin in hypoxic GCs. In conclusion, our study elucidates that melatonin, through MTNR1B activation, fosters SOD2 expression, effectively quelling mtROS-JNK-FOXO1-mediated apoptosis in follicular GCs under hypoxic stress.

5,7-Dihydroxy-4-methylcoumarin modulates the JNK/FoxO1 signaling pathway to attenuate cisplatin-induced ototoxicity by suppressing oxidative stress and apoptosis in vitro

5,7-Dihydroxy-4-methylcoumarin (D4M) is attributed to free radical scavenging effects, with wide application for anti-oxidation. This work aimed to assess D4M's impact on cisplatin-induced ototoxicity. The cell viability was estimated with CCK-8 assay. Apoptosis was detected by the Annexin V-FITC and PI assay. The reactive oxygen species (ROS) level was determined by MitoSOX-Red and CellROX-Green probes. Mitochondrial membrane potential was analyzed with TMRM staining. Immunofluorescence was utilized for hair cells and spiral ganglion neuron detection. Apoptosis-associated proteins were assessed by cleaved caspase-3 and TUNEL staining. These results showed that D4M pretreatment protected hair cells from cisplatin-induced damage, increased cell viability, and decreased apoptosis in House Ear Institute-Organ of Corti1 (HEI-OC1) cells and neonatal mouse cochlear explants. D4M significantly inhibited cisplatin-induced mitochondrial apoptosis and reduced ROS accumulation. In addition, the protective effect of D4M on cisplatin-induced ototoxicity was also confirmed in cochlear hair cells and spiral ganglion neurons in neonatal mice. Mechanistic studies showed that D4M markedly downregulated p-JNK and elevated the expression ratio of p-FoxO1/FoxO1, thereby reducing cisplatin-induced caspase-dependent apoptosis. Meanwhile, D4M-related protection of HEI-OC1 cells was significantly blunted by JNK signaling induction with anisomycin. This study supports the possibility that D4M may be used as a new compound to prevent cisplatin-related hearing loss.

Protective Effect of Buckwheat Polysaccharide on Streptozotocin-Induced Kidney Injury in Diabetic Rats and the Possible Mechanism

We intend to explore the mechanism underlying the effect of Buckwheat polysaccharide on kidney damage in diabetics. In this study, rats received 5 week-STZ injection to induce type 2 diabetes and then were administered with 8-week buckwheat polysaccharide followed by analysis of the diabetes-index and kidney histopathological changes by immunohistochemistry and ELISA as well as the expression of kidney Col IV, Akt, TGF-β1, FN, FoxO1 and MnSOD by western blot and RT-qPCR. Diabetic nephropathy rats exhibited significantly increased blood glucose, kidney body mass index, Scr and glomerular mesangial index, with thickened glomerular basement membrane, and elevated BUN and urinary albumin excretion. Besides, podocyte was fused as demonstrated by significantly decreased expression of renal TGF-β1, FN, Col IV mRNA and renal MnSOD mRNA. In conclusion, Buckwheat polysaccharides significantly alleviate kidney injury in diabetes possibly through regulation of FoxO1/MnSOD axis.

Sulforaphane Acts Through NFE2L2 to Prevent Hypoxia-Induced Apoptosis in Porcine Granulosa Cells via Activating Antioxidant Defenses and Mitophagy

In mammals, a vast majority of ovarian follicles undergo atresia, which is caused by granulosa cell (GC) apoptosis. GCs in follicles are exposed to low oxygen. Hypoxia triggers reactive oxygen species (ROS) generation, which leads to cell oxidative stress and apoptosis. Sulforaphane (SFN), a phytochemical isothiocyanate enriched in cruciferous vegetables, has exhibited a crucial role in mitigating oxidative stress. To explore the effect of SFN on porcine GC apoptosis in a hypoxic environment, we handled the established hypoxia model (1% O₂) of cultured porcine GCs with SFN. Results showed that SFN rescued hypoxia-induced apoptosis and viability of GCs. Meanwhile, SFN increased the expression of antioxidant enzymes and reduced the accumulation of ROS in GC cytoplasm and mitochondria under hypoxia. Mechanically, SFN activated the transcription factor of redox-sensitive nuclear factor-erythroid 2-related factor 2 (NFE2L2) entering the nucleus, further inducing mitophagy and increased antioxidant capacity, finally alleviating the adverse effect of hypoxia on porcine GCs. In conclusion, SFN inhibited hypoxia-evoked GC apoptosis by activating antioxidant defenses and mitophagy through NFE2L2. New targets may be provided for regulating follicular development and atresia by these findings.

Effects of nanoplastic on cell apoptosis and ion regulation in the gills of Macrobrachium nipponense

Nanoplastic, ubiquitous in aquatic environments, are raising concern worldwide. However, studies on nanoplastic exposure and its effects on ion transport in aquatic organisms are limited. In this study, the juvenile oriental river shrimp, Macrobrachium nipponense, was exposed to five levels of nanoplastic concentrations (0, 5, 10, 20, 40 mg/L) in order to evaluate cell viability, ion content, ion transport, ATPase activity, and related gene expression. The results showed that the apoptosis rate was higher in the high concentration nanoplastic group (40 mg/L) compared to the low concentration nanoplastic group (5 mg/L) and the control group (0 mg/L). The ion content of sodium (Na⁺), potassium (K⁺), chloride (Cl^-), and calcium (Ca²⁺) showed a decreasing trend in gill tissue compared to the control group. The Na⁺K⁺-ATPase, V(H)-ATPase, Ca²⁺Mg²⁺-ATPase, and total ATPase activities in the gills of M. nipponense showed a general decrease with the increasement of nanoplastic concentration and time of exposure. When increasing nanoplastic concentration, the expression of ion transport-related genes in the gills of M. nipponense showed first rise then descend trend. As elucidated by the results, high nanoplastic concentrations have negative effect on cell viability, ion content, ion transport ATPase activity, and ion transport-related gene expression in the gills of M. nipponense. This research provides a theoretical foundation for the toxic effects of nanoplastic in aquaculture.

Comparison of immune defense and antioxidant capacity between broodstock and hybrid offspring of juvenile shrimp (Macrobrachium nipponense): Response to acute ammonia stress

Ammonia is a major environmental pollutant in the aquatic system that poses a great threat to the health of shrimp. Macrobrachium nipponense, as one of the large-yield farmed shrimp, is facing germplasm degradation. Genetic improvement through hybridization is one of the effective methods to solve this problem. However, there are few studies on the effects of ammonia nitrogen on the germplasm resources of M. nipponense. In this study, the broodstock populations (Dianshan, DS) and hybrid offspring (DS ♀ × CD [Changjiang, CJ ♂ × Dongting, DT ♀], SCD) were exposed to 0, 5, or 20 mg/L of ammonia for 96 h. The survival rate of the SCD group was greater than the DS group, although there were no significant differences in weight gain rate and length gain rate (p > 0.05). The number of positive cells and apoptosis rates in the DS group were significantly greater than in the SCD group after ammonia exposure (p < 0.05). As the ammonia concentration increased, the antioxidant enzyme activities in the SCD group were significantly higher than DS group, while the hepatotoxicity enzyme activities in the SCD group were significantly lower than DS group (p < 0.05). The trends in the expression of antioxidant- and immune-related genes were generally consistent with the activities of antioxidant enzymes. Our study found that the hybrid population had stronger stress resistance than their parent populations at the same ammonia concentration. This study confirms our speculation that hybrid population has a greater advantage in antioxidant immunity, which also provides reference for the follow-up study of chronic ammonia toxicity.

FSH mediates estradiol synthesis in hypoxic granulosa cells by activating glycolytic metabolism through the HIF-1α-AMPK-GLUT1 signaling pathway

Owing to the avascular environment within ovarian follicles, granulosa cells (GCs) are believed to live in a hypoxic niche. Follicle-stimulating hormone (FSH)-mediated steroidogenesis is crucial for normal growth and maturation of ovarian follicles, but it remains unclear how FSH stimulates estradiol (E2) synthesis under hypoxic conditions. Here, we aimed to explore whether FSH affects the ATP production required for estrogen synthesis from the perspective of glucose metabolism. It was observed that the levels of both E2 and HIF-1α were markedly increased in a dose-dependent manner in mouse ovarian GCs after the injection of FSH in vivo, indicating that hypoxia/HIF-1α may be relevant to FSH-induced E2 synthesis. By treating hypoxic GCs with FSH in vitro, we further revealed that the activation of the AMP-activated protein kinase (AMPK)–GLUT1 pathway, which in turn stimulates ATP generation, may be essential for FSH-mediated E2 production during hypoxia. In contrast, inhibition of AMPK or GLUT1 with siRNAs/antagonist both repressed glycolysis, ATP production, and E2 synthesis despite FSH treatment. Moreover, blocking HIF-1α activity using siRNAs/PX-478 suppressed AMPK activation, GLUT1 expression, and E2 levels in FSH-treated GCs. Finally, the in vitro findings were verified in vivo, which showed markedly increased AMPK activity, GLUT1 expression, glycolytic flux, ATP levels, and E2 concentrations in ovarian GCs following FSH injection. Taken together, these findings uncovered a novel mechanism for FSH-regulating E2 synthesis in hypoxic GCs by activating glycolytic metabolism through the HIF-1α–AMPK–GLUT1 pathway.

Influence of Melatonin on Behavioral and Neurological Function of Rats with Focal Cerebral Ischemia-Reperfusion Injury via the JNK/FoxO3a/Bim Pathway

OBJECTIVE

To investigate the influence of melatonin on behavioral and neurological function of rats with focal cerebral ischemia-reperfusion injury via the JNK/FoxO3a/Bim pathway.

METHODS

One hundred and twenty healthy male SD rats were randomized into the model group (Model: the middle cerebral artery occlusion (MCAO) model was constructed and received an equal volume of normal saline containing 5% DMSO), sham operation group (Sham: received no treatment except normal feeding), and low, medium, and high dose of melatonin group (L-MT, M-MT, and H-MT intraperitoneally injected 10, 20, and 40 mg/kg melatonin 30 min after IR, respectively), with 24 rats in each group. Following 24 h of reperfusion, the rats in each of the above groups were tested for neurological deficit symptoms and behavioral changes to screen the rats included in the study. HE and TUNEL stainings were performed to observe pathological changes. Levels of oxidative stress-related indexes, inflammatory factor-related indexes, nuclear factor-κB p65 (NF-κB p65), and interferon-γ (IFN-γ) in the rat brain were measured by ELISA. The JNK/FoxO3a/Bim pathway-related proteins as well as Bcl-2, Caspase-3, and Bax were examined using Western blot.

RESULTS

Detection of behavioral indicators showed that the MACO model was successfully constructed in rats. L-MT, M-MT, and L-MT groups presented reduced malondialdehyde (MDA), reactive oxygen species (ROS), tumor necrosis factor- (TNF-) α, interleukin- (IL-) 6, IL-1β, IFN-γ, NF-κB p65, and apoptosis compared with the Model group (P < 0.05), and the improvement degree was better in the M-MT group versus the L-HT group. Bcl-2 protein expression in the brain tissue of L-MT, M-MT, and H-MT groups increased significantly, while Bax, Caspase-3, p-JNK, p-FoxO3a, and Bim protein expression declined markedly, versus the Model group (P < 0.05). The changes of indexes were greater in the M-MT group compared with that in the L-MT group. No significant difference was observed in all the above indexes between the M-MT group and the H-MT group (P > 0.05).

CONCLUSIONS

In the MACO rat model, melatonin can effectively reduce Bax and Caspase-3 levels by modulating the JNK/FoxO3a/Bim pathway, inhibit neuronal apoptosis, and alleviate neurological deficits by reducing the release of proinflammatory mediators, with anti-inflammatory and antioxidant effects. In addition, 20 mg/kg is the optimal melatonin concentration.

Transcriptional regulation of HIF1α-mediated STAR expression in murine KK1 granulosa cell line involves cJUN, CREB and CBP-dependent pathways

Gonadal function is connected to hypoxia, with hypoxia-inducible factor (HIF) 1α, as a component of HIF1-complexes, regulating cellular adaptation to hypoxic conditions. In the ovary, it regulates follicular maturation, ovulation and luteal development. At the cellular level, HIF1-complexes coordinate the expression of steroidogenic acute regulatory protein (STAR), and thereby ovarian steroidogenesis. The functionality of STAR is associated with the cAMP/PKA-dependent pathways. In vitro, HIF1α is required for basal and cAMP-induced STAR expression, under ambient and reduced oxygen (O₂) tension. Lowering O₂ increases the responsiveness of the Star promoter towards cAMP and PKA mediates activation/phosphorylation (P) of several transcriptional factors, including cJUN and cAMP response element-binding protein (CREB), whose functionality is linked to HIF1 through utilization of CREB-binding protein (CBP). Since the mechanisms underlying HIF1α-dependent expression of STAR remain unknown, we investigated the involvement of HIF1α in CREB-, cJUN- and CBP-mediated expression of STAR using a well-characterized steroidogenic model, murine KK1 granulosa cells; ambient and lowered (10%) O₂ were applied. Our main findings were that while functional suppression of the α-subunit of HIF1 lowered STAR/P-STAR and steroidogenic output from granulosa cells, surprisingly the levels of P-CREB and its transcriptional activity were strongly induced. However, its association with the Star promoter was decreased, indicating dissociation of P-CREB from the promoter. Further, suppression of HIF1 activity ultimately diminished the expression of cJUN/P-cJUN and CBP. Finally, the study suggests that HIF1-complex: (1) regulates cJUN expression in granulosa cells, (2) is involved in regulating the recruitment of P-CREB to the Star promoter in (3) a mechanism which possibly involves the HIF1-dependent regulation of CBP expression.

Network pharmacology-based study on the mechanism of scutellarin against zearalenone-induced ovarian granulosa cell injury

Zearalenone(ZEA) is a kind of mycotoxin widely existing in nature, its toxic effects can lead to the reproductive disorders in humans and animals. The aim of this study was to investigate the mechanism of scutellarin against ovarian granulosa cell(GCs) injury induced by ZEA based on network pharmacology, molecular docking method. The results show that 293 drug targets of scutellarin were found from PhamMapper database, and 583 disease targets were selected from Genecards database. Finally, 57 scutellarin targets were obtained for the repair of GCs injury with gene intersection. The protein-protein interaction(PPI), gene ontology(GO) and kyoto encyclopedia of genes and genomes(KEGG) analysis indicated that MAPK signaling pathway was most likely activated by scutellarin. Scutellarin with JNK or Caspase-3 had minimal and negative free binding energy in molecular docking analysis, indicating that they might be the acting targets of scutellarin. Cell viability was significantly decreased in ZEA treated cells. However, GCs viability, the level of estradiol(E₂) and progesterone(P₄) were significantly increased with addition of scutellarin to ZEA treated cells. Western blot analysis showed that scutellarin significantly reduced the expression of JNK, c-jun and Cleaved-caspasee-3 in GCs compared with ZEA treatment. In conclusion, scutellarin could alleviate the ovarian GCs injury by down-regulating the expression of JNK, c-jun and Cleaved-caspase-3 through the activation of MAPK/JNK signaling pathway. Our results will provide a theoretical foundation for the treatment of reproductive disorders with scutellarin.

Periplaneta americana peptide decreases apoptosis of pig-ovary granulosa cells induced by H2 O2 through FoxO1

Oxidative stress can induce apoptosis of granulosa cells and lead to follicular atresia, thereby reducing the number of pigs giving birth. The aim of this study was to investigate the protective effect of Periplaneta americana peptide (PAP) on the apoptosis of the granulosa cells of pig ovaries (PGCs) induced by hydrogen peroxide (H₂ O₂ ) via FoxO1. PGCs were treated with H₂ O₂ to establish a cell apoptosis model. Cell viability was measured using the cell counting kit-8 (CCK-8) assay, and cell apoptosis was detected using flow cytometry. The malondialdehyde (MDA) level and nitric oxide (NO) content were detected to reflect the oxidative stress. Western blotting, qRT-PCR and overexpression were undertaken to determine the expression of FoxO1 and caspase-3, and immunofluorescence was used to detect FoxO1 in the nucleus and cytoplasm. PGCs were treated with 100 μM H₂ O₂ for 6 hr, which resulted in oxidative damage and apoptosis and an apoptosis rate for PGCs of 32.95%. Next, PGCs were treated with 400 μg/ml PAP for 24 hr to repair the apoptosis induced by H₂ O₂ . PAP improved cell viability in H₂ O₂ -stimulated PGCs, the increased MDA level and NO content caused by H₂ O₂ stimulation were reversed and the apoptotic rate of PGCs was reduced. The qRT-PCR and Western blotting results indicated that PAP decreased the H₂ O₂ -induced apoptosis and the expression of FoxO1 and caspase-3 in PGCs. The effect of PAP was the same following FoxO1 overexpression. FoxO1 was expressed in the nucleus when stimulated by H₂ O₂ or overexpression; however, it migrated to the cytoplasm following PAP treatment. PAP decreased the apoptosis of PGCs induced by H₂ O₂ by regulating FoxO1 expression and nuclear translocation.

SMAD4 Inhibits Granulosa Cell Apoptosis via the miR-183-96-182 Cluster and FoxO1 Axis

The miR-183-96-182 cluster is a polycistronic miRNA cluster necessary for ovarian functions in mammals. However, its transcriptional regulation in the ovary is largely unclear. In this study, we characterized the promoter region of the porcine miR-183-96-182 cluster, and showed that SMAD4 may function as a transcriptional activator of the miR-183-96-182 cluster in GCs through direct binding to SBE motifs in its promoter. SMAD4 may inhibit GC apoptosis via suppression of FoxO1, an effector of GC apoptosis and a direct target of the miR-183-96-182 cluster, by inducing the miR-183-96-182 cluster, and this process may be regulated by the TGF-β/SMAD signaling pathway. Our findings uncovered the regulatory mechanism of miR-183-96-182 cluster expression in GCs and demonstrated that TGF-β1/SMAD4/miR-183-96-182 cluster/FoxO1 may be a potential pathway for regulating follicular atresia and female reproduction.

DHA ameliorates MeHg‑induced PC12 cell apoptosis by inhibiting the ROS/JNK signaling pathway

Recent studies have reported that methylmercury (MeHg) induces neuronal apoptosis, which is accompanied by abnormal neurological development. Despite the important role of docosahexaenoic acid (DHA) in maintaining the structure and function of the brain, as well as improving neuronal apoptosis induced by MeHg, the exact mechanism remains unknown. The present study hypothesized that the reactive oxygen species (ROS)-mediated JNK signaling pathway may be associated with the protective effect of DHA against MeHg-induced PC12 cell apoptosis. Cell Counting Kit-8, TUNEL staining, flow cytometry, ROS detection, PCR and western blot analysis were performed. The results demonstrated that MeHg inhibited the activity of PC12 cells, causing oxidative damage and promoting apoptosis; however, DHA significantly attenuated this effect. Mechanistic studies revealed that MeHg increased intracellular ROS levels and JNK protein phosphorylation, and decreased the expression levels of the anti-apoptotic protein Bcl-2, whereas DHA reduced ROS levels and JNK phosphorylation, and increased Bcl-2 expression. In addition, the ROS inhibitor N-acetyl-l-cysteine (NAC) was used to verify the experimental results. After pretreatment with NAC, expression levels of Bcl-2, Bax, phosphorylated-JNK and JNK were assessed. Bcl-2 protein expression was increased and the Bcl-2/Bax ratio was increased. Moreover, the high expression levels of phosphorylated-JNK induced by MeHg were significantly decreased. Based on the aforementioned results, the present study indicated that the effects of DHA against MeHg-induced PC12 cell apoptosis may be mediated via the ROS/JNK signaling pathway.

Melatonin Alleviates Hypoxia-Induced Apoptosis of Granulosa Cells by Reducing ROS and Activating MTNR1B-PKA-Caspase8/9 Pathway

In mammalian ovaries, the avascular environment within follicular cavity is supposed to cause hypoxic status in granulosa cells (GCs), leading to apoptotic cell death accompanied by cumulative reactive oxygen species (ROS) production. Melatonin (N-acetyl-5-methoxytryptamine, MT), a broad-spectrum antioxidant that exists in porcine follicle fluid, was suggested to maintain GCs survival under stress conditions. In this study, using the established hypoxic model (1% O₂) of cultured porcine GCs, we explored the effect of MT on GCs apoptosis. The results showed that MT restored cell viability and reduced the apoptosis of GCs during hypoxia exposure. In addition, GCs treated with MT exhibited decreased ROS levels and increased expression of antioxidant enzymes including heme oxygenase-1 (HO-1), glutathione S-transferase (GST), superoxide dismutase 1 (SOD1), and catalase (CAT) upon hypoxia incubation. Moreover, the hypoxia-induced expression of cleaved caspase 3, 8, and 9 was significantly inhibited after MT treatment. In contrast, blocking melatonin receptor 2 (MTNR1B) with a competitive antagonist 4-phenyl-2-propionamidotetralin (4P-PDOT) diminished the inhibitory effects of MT on caspase 3 activation. By detecting levels of protein kinase (PKA), a downstream kinase of MTNR1B, we further confirmed the involvement of MT–MTNR1B signaling in mediating GCs protection during hypoxia stress. Together, the present data provide mechanistic evidence suggesting the role of MT in defending GCs from hypoxia-induced apoptosis.