The Impact of Hepatitis C Virus Genotypes on Oxidative Stress Markers and Catalase Activity

Targeting POLRMT by a first-in-class inhibitor IMT1 inhibits osteosarcoma cell growth in vitro and in vivo

Osteosarcoma (OS) is a highly aggressive form of bone cancer that predominantly affects adolescents and young adults. In this study, we have undertaken an investigation into the potential anti-OS cell activity of IMT1 (inhibitor of mitochondrial transcription 1), a first-in-class inhibitor of RNA polymerase mitochondrial (POLRMT). IMT1 exhibited a profound inhibitory effect on cell survival, proliferation, cell cycle progression, and migration in primary and immortalized OS cells. Furthermore, this POLRMT inhibitor elicited apoptosis in the OS cells, without, however, inducing cytotoxicity in human osteoblasts or osteoblastic cells. IMT1 disrupted mitochondrial functions in OS cells, resulting in mitochondrial depolarization, oxidative injury, lipid peroxidation, and ATP reduction in OS cells. Silencing POLRMT using targeted shRNA closely mimicked the actions of IMT1 and exerted potent anti-OS cell activity. Importantly, IMT1's effectiveness was diminished in POLRMT-silenced OS cells. Subsequent investigations revealed that IMT1 suppressed the activation of the Akt-mammalian target of rapamycin (mTOR) cascade in OS cells. IMT1 treatment or POLRMT silencing in primary OS cells led to a significant reduction in Akt1-S6K-S6 phosphorylation. Conversely, it was enhanced upon POLRMT overexpression. The restoration of Akt-mTOR activation through the introduction of a constitutively active S473D mutant Akt1 (caAkt1) mitigated IMT1-induced cytotoxicity in OS cells. In vivo, oral administration of IMT1 robustly curtailed the growth of OS xenografts in nude mice. Furthermore, IMT1 suppressed POLRMT activity, impaired mitochondrial function, repressed Akt-mTOR activation, and induced apoptosis within xenograft tissues. Collectively, these findings underscore the potent growth-inhibitory effects attributed to IMT1 via targeted POLRMT inhibition. The utilization of this POLRMT inhibitor carries substantial therapeutic promise in the context of OS treatment.

Endothelial cell-derived RSPO3 activates Gαi1/3-Erk signaling and protects neurons from ischemia/reperfusion injury

The current study explores the potential function and the underlying mechanisms of endothelial cell-derived R-spondin 3 (RSPO3) neuroprotection against ischemia/reperfusion-induced neuronal cell injury. In both neuronal cells (Neuro-2a) and primary murine cortical neurons, pretreatment with RSPO3 ameliorated oxygen and glucose deprivation (OGD)/re-oxygenation (OGD/R)-induced neuronal cell death and oxidative injury. In neurons RSPO3 activated the Akt, Erk and β-Catenin signaling cascade, but only Erk inhibitors reversed RSPO3-induced neuroprotection against OGD/R. In mouse embryonic fibroblasts (MEFs) and neuronal cells, RSPO3-induced LGR4-Gab1-Gαi1/3 association was required for Erk activation, and either silencing or knockout of Gαi1 and Gαi3 abolished RSPO3-induced neuroprotection. In mice, middle cerebral artery occlusion (MCAO) increased RSPO3 expression and Erk activation in ischemic penumbra brain tissues. Endothelial knockdown or knockout of RSPO3 inhibited Erk activation in the ischemic penumbra brain tissues and increased MCAO-induced cerebral ischemic injury in mice. Conversely, endothelial overexpression of RSPO3 ameliorated MCAO-induced cerebral ischemic injury. We conclude that RSPO3 activates Gαi1/3-Erk signaling to protect neuronal cells from ischemia/reperfusion injury.

Oxidative stress and toxicity produced by arsenic and chromium in broiler chicks and application of vitamin E and bentonite as ameliorating agents

The present study investigated the adverse effects of arsenic and chromium in broilers and ascertained the role of vitamin E and bentonite in alleviating their harmful effects. For this purpose, we experimented on 180 one-day-old broiler chickens. The feed was administered to broiler chicks of groups 2, 6, 7, 8, and 9 chromium @ (270 mg.kg−1 BW). Groups 3, 6, 7, 8, and 9 were administered arsenic @ (50 mg.kg−1 BW). Groups 4, 7, and 9 received vitamin E (150 mg.kg−1 BW), and groups 5, 8, and 9 received bentonite (5%), respectively. Group 1 was kept in control. All the broiler chicks treated with chromium and arsenic showed a significant (p < 0.05) decline in erythrocytic parameters on experimental days 21 and 42. Total proteins decreased significantly, while ALT, AST, urea, and creatinine increased significantly (p < 0.05). TAC and CAT decreased significantly (p < 0.05), while TOC and MDA concentrations increased significantly (p < 0.05) in chromium and arsenic-treated groups on experimental days 21 and 42. Pearson correlation analysis revealed a strong positive correlation between TAC and CAT (Pearson correlation value = 0.961; p < 0.001), similarly TOC and MDA positive correlation (Pearson correlation value = 0.920; p < 0.001). However, TAC and CAT showed a negative correlation between TOC and MDA. The intensity of gross and microscopic lesions was more in chromium (270 mg.kg−1) and arsenic (50 mg.kg−1) singly or in combination-treated groups. Thus, broiler chicks treated with chromium plus arsenic exhibited higher gross and microscopic lesion intensity than other treated groups. Fatty degeneration, severe cytoplasmic vacuolar degeneration, and expansion of sinusoidal spaces were the main lesions observed in the liver. Kidneys showed renal epithelial cells necrosis, glomerular shrinkage, and severe cytoplasmic vacuolar degeneration. Co-administration of bentonite along with chromium and arsenic resulted in partial amelioration (group 8) compared to groups 7 and 9, administered arsenic + chromium + vitamin E and arsenic + chromium + vitamin E + bentonite, respectively. It was concluded that arsenic and chromium cause damage not only to haemato-biochemical parameters but also lead to oxidation stress in broilers. Vitamin E and bentonite administration can ameliorate toxicity and oxidative stress produced by arsenic and chromium.

[Hepatitis B and C: mechanisms of virus-induced liver pathogenesis and tumorigenesis]

Worldwide, the hepatitis B and hepatitis C viruses (HBV, HCV) are the most relevant causative viral agents of a chronic hepatitis (inflammation of the liver). At present, more than 250 million people suffer from a chronic HBV infection globally, resulting in 0.8 million deaths per year. A chronic HCV infection accounts for about 70 million cases worldwide, leading to a death toll of about 1 million per year. An approved vaccine is only available against an HBV infection. Both HBV and HCV infections result in a highly increased risk of developing liver fibrosis, cirrhosis, and a hepatocellular carcinoma (HCC).This review aims to describe mechanisms of the HBV- and HCV-associated pathogenesis. The focus is on the interplay between a chronic infection with intracellular signaling transduction, metabolic pathways with an emphasis on lipid metabolism, the establishment of liver fibrosis and cirrhosis during a chronic infection, and the mechanisms of the onset of a virally induced HCC.Despite there being great advances in the characterization of viral life cycles and the development of robust antiviral strategies, significant hurdles persist: gaining a better understanding of the mechanisms that drive virus-associated pathogenesis as well as increasing insights regarding different viral genotypes having impacts on alternate pathogeneses.

Reactive Oxygen Species in the Adverse Outcome Pathway Framework: Toward Creation of Harmonized Consensus Key Events

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are formed as a result of natural cellular processes, intracellular signaling, or as adverse responses associated with diseases or exposure to oxidizing chemical and non-chemical stressors. The action of ROS and RNS, collectively referred to as reactive oxygen and nitrogen species (RONS), has recently become highly relevant in a number of adverse outcome pathways (AOPs) that capture, organize, evaluate and portray causal relationships pertinent to adversity or disease progression. RONS can potentially act as a key event (KE) in the cascade of responses leading to an adverse outcome (AO) within such AOPs, but are also known to modulate responses of events along the AOP continuum without being an AOP event itself. A substantial discussion has therefore been undertaken in a series of workshops named "Mystery or ROS" to elucidate the role of RONS in disease and adverse effects associated with exposure to stressors such as nanoparticles, chemical, and ionizing and non-ionizing radiation. This review introduces the background for RONS production, reflects on the direct and indirect effects of RONS, addresses the diversity of terminology used in different fields of research, and provides guidance for developing a harmonized approach for defining a common event terminology within the AOP developer community.

Phosphoglycerate kinase 1 silencing by a novel microRNA microRNA-4523 protects human osteoblasts from dexamethasone through activation of Nrf2 signaling cascade

Nuclear-factor-E2-related factor 2 (Nrf2) cascade activation can ameliorate dexamethasone (DEX)-induced oxidative injury and death in human osteoblasts. Phosphoglycerate kinase 1 (PGK1) depletion is shown to efficiently activate Nrf2 signaling by inducing methylglyoxal modification of Kelch-like ECH-associated protein 1 (Keap1). We here identified a novel PGK1-targeting microRNA: microRNA-4523 (miR-4523). RNA fluorescent in situ hybridization, RNA pull-down, and Argonaute-2 RNA immunoprecipitation results confirmed a direct binding between miR-4523 and PGK1 mRNA in primary human osteoblasts and hFOB1.19 osteoblastic cells. Forced overexpression of miR-4523, using a lentiviral construct, robustly decreased PGK1 3'-UTR (untranslated region) luciferase activity and downregulated its expression in human osteoblasts and hFOB1.19 cells. Furthermore, miR-4523 overexpression activated the Nrf2 signaling cascade, causing Keap1-Nrf2 disassociation, Nrf2 protein stabilization, and its nuclear translocation as well as transcription activation of Nrf2-dependent genes (NQO1, GCLC, and HO1) in human osteoblasts. By expressing a UTR-null PGK1 construct, miR-4523 overexpression-induced Nrf2 cascade activation was however largely inhibited. Importantly, DEX-induced reactive oxygen species production, oxidative injury, and cell apoptosis were significantly attenuated by miR-4523 overexpression in human osteoblasts and hFOB1.19 cells. Such actions by miR-4523 were abolished by Nrf2 shRNA or knockout, but mimicked by PGK1 knockout (using CRISPR/Cas9 method). In PGK1 knockout human osteoblasts, miR-4523 overexpression failed to further increase Nrf2 cascade activation and offer osteoblast cytoprotection against DEX. Significantly, miR-4523 is downregulated in human necrotic femoral head tissues of DEX-taking patients. Together, PGK1 silencing by miR-4523 protected human osteoblasts from DEX through activation of the Nrf2 signaling cascade.