Quercetin Alleviates Toxicity Induced by High Levels of Copper in Porcine Follicular Granulosa Cells by Scavenging Reactive Oxygen Species and Improving Mitochondrial Function

Impact of quercetin on autophagy and apoptosis induced by a high concentration of CuSO4 in porcine ovarian granulosa cells

Copper is a vital micronutrient necessary for the maintenance of physiological functions. However, excessive amounts can lead to organ damage. Porcine ovarian granulosa cells are damaged by a high concentration of CuSO4, which can reduce the reproductive capacity of sows. Quercetin has shown remarkable efficacy in mitigating the harmful effects of heavy metals. Therefore, the aim of this study was to investigate the effects of a high concentration of CuSO4 on autophagy and apoptosis in porcine ovarian granulosa cells and to explore whether quercetin can counteract these toxic effect. Cell morphology, and the mRNA expression levels of autophagy-related genes (LC3-Ⅰ, ATG5, ATG7, ATG12, Beclin1, mTOR, LC3-Ⅱ and P62) were significantly changed upon treatment with 200 and 400 µM CuSO4. Treatment with 200 µM CuSO4 increased expression of P62 protein (P<0.05), promoted LC3-Ⅰ to LC3-Ⅱ conversion (P<0.05), and reduced PINK1 protein expression and the ATP content (P<0.05). In addition, expression of Caspase3 protein was increased and TUNEL staining indicated that the number of apoptotic cells was increased. However, co-treatment with 10 µM quercetin significantly decreased expression of P62 and conversion of LC3-Ⅰ to LC3-Ⅱ. Furthermore, flow cytometric analysis revealed that addition of 10 µM quercetin significantly reduced apoptosis induced by a high concentration of CuSO4. In summary, the results indicate that a high concentration of CuSO4 can trigger mitochondrial and autophagy dysfunction, activate mitochondrial apoptosis pathway, and exert cytotoxic effects. Quercetin can mitigate autophagy dysfunction, enhance autophagic processes, and alleviate apoptosis.

Molecular mechanism of GSH metabolism and autophagy in NAC-promoted recombinant human serum albumin and follicle stimulating hormone beta fusion protein secretion in Pichia pastoris

The Pichia pastoris expression system is a favorable platform for production of pharmaceutical proteins. Treatment of strains with N-acetyl-L-cysteine (NAC) has been shown to enhance the yield of recombinant proteins, thereby contributing to a reduction in production costs. However, the specific mechanism of action of NAC remains unclear. Previous research has indicated that glutathione (GSH) and autophagy are involved in the increased production of human serum albumin and porcine follicle-stimulating hormone β (HSA-pFSHβ) by NAC. This study investigated the potential interaction between GSH and autophagy in the production of HSA-pFSHβ. The findings indicated that sulfhydryl-free antioxidants such as melatonin, vitamin C, or vitamin E did not exhibit similar effects to NAC in enhancing HSA-pFSHβ yield. Moreover, NAC was found to enhance HSA-pFSHβ production by modulating GSH metabolism to reduce GSH consumption, increase total GSH levels, as well as glutathione peroxidase (GSH-Px) and glutathione reductase (GR) activities. Additionally, inhibition of autophagy through disruption of autophagy scaffolding proteins Atg1 or Atg11 led to an increase in recombinant HSA-pFSHβ production. Furthermore, NAC significantly decreased the phosphorylation of Slt2, and the absence of the SLT2 gene influenced the effect of NAC on HSA-pFSHβ secretion by modulating mitophagy and GSH metabolism. In conclusion, these results suggest a complex interplay between GSH metabolism and autophagy in the regulation of NAC-induced HSA-pFSHβ secretion.

The dual role of ATG7: Regulation of autophagy and apoptosis in porcine ovarian follicular granulosa cells

The regulation of mammalian ovarian development involves the coordinated processes of autophagy and apoptosis. The autophagy-related gene ATG7 plays a pivotal role in mediating crosstalk between these pathways. Despite its recognized importance, the specific function of ATG7 in ovarian follicular granulosa cells remains poorly understood. This study aimed to explore the effects of ATG7 overexpression on apoptosis and autophagy in porcine ovarian follicular granulosa cells and thereby provide insights into the interplay between these fundamental cellular mechanisms. An ATG7 overexpression vector was introduced into cells, followed by assessment of cell proliferation using the CCK-8 assay, quantification of related gene expression via real-time quantitative PCR and western blotting, and evaluation of apoptosis using TUNEL staining. ATG7 exhibited a predominant cytoplasmic localization and additional nuclear expression in porcine ovarian follicular granulosa cells. The transfection efficiency of the vector was initially verified, indicating that its overexpression notably increased expression of ATG7 protein. Further investigations confirmed that overexpression of ATG7 inhibited cell proliferation, stimulated autophagy, and promoted apoptosis in these cells. In summary, overexpression of ATG7 influences the viability of porcine ovarian follicular granulosa cells by regulating the interplay between autophagy and apoptosis. This study not only broadens the understanding of functional regulation of autophagy and apoptosis by ATG7, but also sheds light on the intricate mechanisms governing ovarian follicular atresia.

The protective role of quercetin against copper-induced female reproductive toxicity: Insights from transcriptome analysis

Quercetin has been shown to mitigate the cytotoxic effects of heavy metals. While copper is an essential trace element for bodily functions, excessive intake has been linked to impaired female reproductive function. Transcriptome analysis was employed to identify genes that are differentially expressed in response to high copper and were validated through qRT-PCR and western blotting. ATP content and Tunel were used to identify the damage of mitochondrial and cell apoptosis. PPI analysis revealed that MKI67, TOPII, ASPM, CASP3, PLK1, and TTK are central proteins within the network. Additionally, exposure to elevated levels of copper resulted in the dysregulation of 86 genes associated with mitochondria. Conversely, treatment with quercetin (QUE) in combination with high copper led to the normalization of 42 mitochondria-related genes previously affected by high copper levels. Furthermore, CuSO4 decreases ATP content and induces cell apoptosis, which can be reversed by QUE. Results suggest that elevated copper levels could lead to oxidative stress and apoptosis by inducing mitochondrial damage, while QUE has the potential to mitigate these effects, ultimately safeguarding granulosa cells and halting the progression of cell death. This study provides novel insights into the molecular pathways involved in female reproductive toxicity caused by excessive copper exposure.

Mitochondrial Morphology and Function Abnormality in Ovarian Granulosa Cells of Patients with Diminished Ovarian Reserve

In this study, we examined the changes in the mitochondrial structure and function in cumulus granulosa cells of patients with diminished ovarian reserve (DOR) to explore the causes and mechanisms of decreased mitochondrial quality. The mitochondrial ultrastructure was observed by transmission electron microscope, and the function was determined by detecting the ATP content, reactive oxygen species (ROS) levels, the number of mitochondria, and the mitochondrial membrane potential. The expression of ATP synthases in relation to mitochondrial function was analyzed. Additionally, protein immunoblotting was used to compare the expression levels of mitochondrial kinetic protein, the related channel protein in the two groups. Patients with DOR had abnormal granulosa cell morphology, increased mitochondrial abnormalities, decreased mitochondrial function, and disturbed mitochondrial dynamics. Additionally, the silent information regulator 1 (SIRT1)/phospho-AMP-activated protein kinase (P-AMPK)-peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) pathway expression was decreased, which was speculated to be associated with the decreased mitochondrial mass in the DOR group. The mitochondrial mass was decreased in granulosa cells of patients in the DOR group. The mitochondrial dysfunction observed in granulosa cells of patients in the DOR group may be associated with dysregulation of the SIRT1/P-AMPK-PGC-1α-mitochondrial transcription factor A (TFAM) pathway.