Oxidative Stress in Metabolic and Endocrine Diseases: Basic and Translational Aspects

Upregulation of TXNIP contributes to granulosa cell dysfunction in polycystic ovary syndrome via activation of the NLRP3 inflammasome

Polycystic ovary syndrome (PCOS) is a complex endocrine disease. Thioredoxin-interacting protein (TXNIP) promotes oxidative stress and triggers inflammation. Herein, we investigated the role and potential mechanism of TXNIP in PCOS. In a mouse model of dehydroepiandrosterone (DHEA)-induced PCOS, we found that TXNIP was upregulated in the ovaries, especially in granulosa cells (GCs). TXNIP was also upregulated in testosterone (T)-treated GCs in vitro. Knockdown of TXNIP by lentivirus-constructed shRNA attenuated T-induced GC injury and oxidative stress, as well as inflammation and the NLRP3 inflammasome. The mechanism by which TXNIP promotes inflammation may involve TXNIP dissociation from the TXNIP-TRX complex and binding to NLRP3 to form the inflammasome. Additionally, we verified that knockdown of TXNIP ameliorated ovarian injury and inflammation in mice with DHEA-induced PCOS in vivo. Collectively, we demonstrated that TXNIP is involved in GC inflammation by promoting NLRP3 inflammasome activation in PCOS.

Oxidative Stress and Nuclear Reprogramming: A Pilot Study of the Effects of Reactive Oxygen Species on Architectural and Epigenetic Landscapes

Cell genome integrity is continuously threatened by various sources, both endogenous and exogenous. Oxidative stress causes a multitude of damages, severely affecting cell viability, fidelity of genetic information inheritance, and determining profound alterations in gene expression. Epigenetics represents a major form of gene expression modulation, influencing DNA accessibility to transcription factors and the overall nuclear architecture. When assessing the stress-induced epigenome reprogramming, widely diffused biochemical and molecular approaches commonly fail to incorporate analyses such as architectural chromatin alterations and target molecules precise spatial localization. Unveiling the significance of the nuclear response to the oxidative stress, as well as the functional effects over the chromatin organization, may reveal targets and strategies for approaches aiming at limiting the impact on cellular stability. For these reasons, we utilized potassium bromate treatment, a stressor able to induce DNA damages without altering the cellular microenvironment, hence purely modeling nuclear oxidative stress. By means of high-resolution techniques, we described profound alterations in DNA and histone epigenetic modifications and in chromatin organization in response to the reactive oxygen species.

G0S2 ameliorates oxidized low-density lipoprotein-induced vascular endothelial cell injury by regulating mitochondrial apoptosis

Background

Oxidative low-density lipoprotein (ox-LDL)-induced endothelial cell damage is a major risk factor for atherosclerosis and its related cardiovascular diseases. The G0/G1 switch gene 2 (G0S2) is a multifunctional protein which has been poorly studied in atherosclerosis.

Methods

In this study, ox-LDL was utilized to construct a human aortic endothelial cell (HAEC) injury model.

Results

It was found that ox-LDL impaired cell viability, augmented lactate dehydrogenase (LDH) release, and reduced G0S2 levels in HAECs in a dose-dependent manner. Further, G0S2 overexpression improved the viability and restrained apoptosis of HAECs treated by ox-LDL. Conversely, G0S2 depletion decreased the viability and aggravated apoptosis of HAECs treated by ox-LDL. At the molecular level, G0S2 overexpression significantly increased the secretion of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPH-Px), promoted intracellular reactive oxygen species (ROS) production and malondialdehyde (MDA) content in HAECs under either normal or ox-LDL conditions. Meanwhile, the ox-LDL-induced mitochondrial dysfunction, as demonstrated by decreased mitochondrial membrane potential, translocation of mitochondrial cytochrome c (Cyt-c) to the cytoplasm, and activation of caspase-3 and caspase-9, was significantly reversed by G0S2 overexpression. In addition, G0S2 overexpression promoted the activation of AMP-activated protein kinase (AMPK) and increased the expression of nuclear factor erythroid-2-related factor-2 (Nrf2), sirtuin 1 (SIRT1) and heme oxygenase 1 (HO-1) under normal and ox-LDL conditions.

Conclusions

This study demonstrated that G0S2 protects against ox-LDL-induced vascular endothelial cell injury by regulating oxidative damage and mitochondrial homeostasis and may be a promising target for the treatment of atherosclerosis.