Roles of oxidative stress/JNK/ERK signals in paraquat-triggered hepatic apoptosis

JNK inhibition mitigates sepsis-associated encephalopathy via attenuation of neuroinflammation, oxidative stress and apoptosis

Sepsis-associated encephalopathy (SAE) is a severe complication of sepsis, leading to cognitive dysfunction and neuronal damage. C-Jun N-terminal kinases (JNKs), a subset of the MAP kinase family, have attracted substantial interest for their role in cellular events during sepsis conditions. Previous investigations have established the involvement of JNK signaling against memory impairment and abnormal synaptic plasticity. However, the present study is the first to investigate the effects of JNK inhibition in sepsis-associated cerebral injury and cognitive impairments. This study investigated the neuroprotective effects of SP600125, a selective JNK inhibitor, in cecal ligation and puncture (CLP) mouse model of sepsis. CLP-induced sepsis resulted in significant cognitive impairments, as assessed by the open field test, inhibitory avoidance test, morris water maze, and novel object recognition test. Additionally, septic mice exhibited increased serum levels of neuronal injury markers (S100B and NSE), pro-inflammatory cytokines (TNF-α and IL-1β), and oxidative stress markers (MDA), along with decreased antioxidant levels (GSH, SOD, and CAT). Histological analysis revealed neuronal pyknosis, degeneration, and loss of Nissl bodies in the cortex and hippocampus of septic mice. Furthermore, sepsis-induced blood-brain barrier dysfunction was evident from increased cerebral edema. Treatment with SP600125 (10, 30, and 50 mg/kg) significantly attenuated CLP-induced cognitive deficits, neuronal injury, neuroinflammation, oxidative stress, and apoptosis in a dose-dependent manner. The present study provides preliminary evidence that JNK inhibition by SP600125 exerts neuroprotective effects against sepsis-induced encephalopathy in vivo via suppression of neuroinflammation, oxidative stress, and apoptosis.

The herbicide 2,4-dichlorophenoxyacetic acid induces pancreatic β-cell death via oxidative stress-activated AMPKα signal downstream-regulated apoptotic pathway

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of commonly and widely used organic herbicides in agriculture. It has been reported that 2,4-D can induce adverse effects in mammalian cells. Epidemiological and animal studies have indicated that exposure to 2,4-D is associated with poorer glycemic control and impaired pancreatic β-cell function. However, limited information is available on 2,4-D-induced toxicological effects in β-cells, with the underlying toxicological mechanisms remains unclear. Herein, our results showed that 2,4-D exposure (30-500 μg/mL) significantly reduced cell viability, induced mitochondria dysfunction (including the mitochondrial membrane potential (MMP) loss, the increase in cytosolic cytochrome c release, and the change in Bcl-2 and Bax protein expression), and triggered apoptotic events (including the increased population of apoptotic cells, caspase-3 activity, and caspase-3/-7 and PAPR activation) in RIN-m5F β-cells, accompanied with insulin secretion inhibition. Exposure of cells to 2,4-D could also evoke JNK, ERK1/2, p38, and AMP-activated protein kinase (AMPK)α activation as well as reactive oxygen species (ROS) generation. Pretreatment of cells with compound C (an AMPK inhibitor) and the antioxidantN-acetylcysteine (NAC), but not that SP600125/PD98059/SB203580 (the inhibitors of JNK/ERK/p38, respectively), obviously attenuated the 2,4-D-triggered AMPKα phosphorylation, MMP loss, apoptotic events, and insulin secretion dysfunction,as similar effects with the transfection with AMPKα1-specific siRNA. Of note, buffering the ROS production with NAC obviously prevented the 2,4-D-induced ROS generation as well as AMPKα activation, but the either compound C and AMPKα1-specific siRNA transfection could not effectively reduce 2,4-D-induced ROS generation. Collectively, these findings indicate that the induction of oxidative stress-activated AMPKα signaling is a crucial mechanism underlying 2,4-D-triggered mitochondria-dependent apoptosis, ultimately leading to β-cell death.

lncRNA-NEF regulates hepatic stellate cells proliferation, cell cycle, apoptosis and ECM synthesis through the ERK1/2/c-Fos axis

In this study, we investigated the role of lncRNA-NEF in modulating hepatic stellate cell (HSC) activation, a key process in liver fibrosis. Using the GSE78160 dataset, we identified lncRNA-NEF as downregulated in liver cirrhosis patients. Gene Ontology and KEGG analyses implicated it in transcriptional regulation and cell cycle control. We established an activated HSC model with TGF-β1-treated LX-2 cells and employed RT-qPCR and Western blot to assess lncRNA-NEF and ERK1/2 expression. Lentiviral transfection was used to overexpress lncRNA-NEF in activated LX-2 cells, and its effects on proliferation, apoptosis, and cell cycle were evaluated using EdU staining, CCK-8, Annexin-V PE/7-AAD, TUNEL, and PI-FACS analysis. Overexpression of lncRNA-NEF led to reduced cell proliferation, increased apoptosis, and cell cycle arrest at the S and G2/M phases. We also observed a decrease in ERK1/2, c-Fos, Collagen I, α-SMA, and Bcl-2 expression, and an increase in Caspase-3 expression, as confirmed by Western blot. These results suggest that lncRNA-NEF regulates HSC activation via the ERK1/2/c-Fos axis, potentially offering a therapeutic target for antifibrotic drug development. Our findings provide a molecular basis for understanding the role of lncRNAs in liver fibrosis and highlight the potential of lncRNA-NEF as a novel antifibrotic target.

A focus on c-Jun-N-terminal kinase signaling in sepsis-associated multiple organ dysfunction: Mechanisms and therapeutic strategies

Sepsis is a life-threatening condition characterized by a widespread inflammatory response to infection, inevitably leading to multiple organ dysfunctions. Extensive research, both in vivo and in vitro, has revealed key factors contributing to sepsis, such as apoptosis, inflammation, cytokine release, oxidative stress, and systemic stress. The changes observed during sepsis-induced conditions are mainly attributed to altered signal transduction pathways, which play a critical role in cell proliferation, migration, and apoptosis. C-Jun N-terminal kinases, JNKs, and serine/threonine protein kinases in the mitogen-activated super family have gained considerable interest for their contribution to cellular events under sepsis conditions. JNK1 and JNK2 are present in various tissues like the lungs, liver, and intestine, while JNK3 is found in neurons. The JNK pathway plays a crucial role in the signal transduction of cytokines related to sepsis development, notably TNF-α and IL-1β. Activated JNK leads to apoptosis, causing tissue damage and organ dysfunction. Further, JNK activation is significant in several inflammatory conditions. Pharmacologically inhibiting JNK has been shown to prevent sepsis-associated damage across multiple organs, including the lungs, liver, intestines, heart, and kidneys. Multiple signaling pathways have been implicated in sepsis, including JNK/c-Myc, Mst1-JNK, MKK4-JNK, JNK-dependent autophagy, and Sirt1/FoxO3a. The review examines the role of JNK signaling in the development of sepsis-induced multiple-organ dysfunction through specific mechanisms. It also discusses different therapeutic approaches to target JNK. This review emphasizes the potential of JNKs as targets for the development of therapeutic agents for sepsis and the associated specific organ damage.

Ubiquitination and deubiquitination: Implications for the pathogenesis and treatment of osteoarthritis

Osteoarthritis (OA) is a degenerative disease that affects multiple cells and associated extracellular matrix (ECM). Chondrocytes and chondroextracellular matrix together constitute articular cartilage tissue. Any factors that affect the activity of chondrocytes and destroy the metabolic balance of the chondrocyte ECM will lead to the inability of articular cartilage to perform normal functions. The articular subchondral bone and articular cartilage must be coordinated to resist enough friction and mechanical stress, so the articular subchondral bone lesion will aggravate the articular cartilage defect and vice versa. Synoviocytes, including fibroblast-like synoviocytes (FLSs) and synovial macrophages at the joint, are also important factors that cause low-grade chronic progressive inflammation of OA. Regulation of phenotype transformation of synovial macrophages has become another possible target for the clinical treatment of OA. Ubiquitination and deubiquitination are the main post-translational protein modification pathways in the human body, which are widely involved in multiple signaling pathways and physiological processes. Naturally, they also play a very important regulatory role in the occurrence and development of OA. These effects are summarized in this review, including (A) regulating the aging and apoptosis of chondrocytes, FLSs and osteoblasts; (B) regulation of ECM degradation; (C) regulation of macrophage phenotypic transformation; (D) modulation of skeletal muscle and adipose tissues. Ubiquitination targeting drugs for OA treatment are also listed. Depending on the high efficiency of ubiquitination and deubiquitination, understanding OA-related ubiquitination pathways can help design more efficient drugs to treat OA and provide more potential targets for clinical treatment. The Translational Potential of This Article. In this paper, the ubiquitination-related pathways in osteoarthritis (OA), including aging, apoptosis and autophagy in chondrocytes, osteoblasts, FLSs and macrophages were investigated. In particular, several ubiquitination-related targets are expected to be effective approaches for OA clinical treatment. In addition, in the process of OA occurrence and development, the complex relationship between the local joint area and other tissues including skeletal muscle and adipose tissue is also discussed. These myokines and adipokines from musculoskeletal tissues are all expected to become efficient targets for OA treatment apart from the joint itself. In addition, those myokines secreted by cardiovascular tissues would show potential therapeutic effects as well. What if altering the contents for these ubiquitination-related targets in the serum through exercise will provide a new idea for OA therapy or prevent OA from deteriorating continuously?

Improvement of inhaled paraquat induced lung and systemic inflammation, oxidative stress and memory changes by safranal

The effects of safranal and pioglitazone alone and their combination on inhaled paraquat (PQ)-induced systemic oxidative stress and inflammation as well as behavioral changes were examined in rats. In this study, animals were exposed to saline (Ctrl) or PQ (PQ groups) aerosols. PQ exposed animals were treated with dexamethasone, 0.8 and 3.2 mg/kg/day safranal (Saf-L and Saf-H), 5 mg/kg/day pioglitazone (Pio), and Saf-L + Pio for 16 days during PQ exposure period. PQ group showed increased numbers of total and differential WBCs in blood and bronchoalveolar lavage fluid (BALF), increased malondialdehyde (MDA), in the serum BALF and brain reduced thiol, catalase (CAT), and superoxide dismutase (SOD) levels compared to the control group (for all, p < 0.001). The escape latency and traveled distance were enhanced, but the time spent in the target quadrant in the probe day and the latency to enter the dark room 3, 24, 48, and 72 h after receiving an electrical shock, (in the shuttle box test) were decreased in the PQ group (p < 0.05 to P < 0.001). In all treated groups, all measure values were improved compared to PQ group (p < 0.05 to p < 0.001). In combination treated group of Saf-L + Pio, most measured values were more improved than the Saf-L and Pio groups (p < 0.05 to p < 0.001). Saf and Pio improved PQ-induced changes similar to dexamethasone but the effects produced by combination treatments of Saf-L + Pio were more prominent than Pio and Saf-L alone, suggesting a potentiating effect for the combination of the two agents.