Mitochondrial Oxidative Stress Research Articles

Activation of sigma-1 receptor ameliorates sepsis-induced myocardial injury by mediating the Nrf2/HO1 signaling pathway to attenuate mitochondrial oxidative stress

BackgroundSepsis is a condition that triggers the release of large amounts of reactive oxygen species and inflammatory factors in the body, leading to myocardial injury and cardiovascular dysfunction — an important contributor to the high mortality rate associated with sepsis. Although it has been demonstrated that the sigma-1 receptor (S1R) is essential for preventing oxidative stress, its effectiveness in treating sepsis is yet unknown. AimThis study aimed to investigate the role and mechanisms of S1R activation in sepsis-induced myocardial injury. MethodsA model of sepsis-induced myocardial injury was constructed by performing cecum ligation and puncture(CLP) surgery on rats. Flv or BD1047 were intraperitoneally injected into rats for one consecutive week before performing CLP, and then intraperitoneally injected into the rats again 1 h after the surgery.The effects of Flv and BD1047 were detected by HE staining, immunofluorescence staining, IHC staining, echocardiography measurements,TUNEL, oxidative stress detection, TEM, flow cytometry and western blot. We further validated the mechanism in vitro using neonatal rat cardiomyocites and H9C2 cells. ResultsS1R protein level was reduced in the hearts of septic rats, whereas administration of Flv, an S1R activator, ameliorated myocardial injury, mitochondrial oxidative stress, and pathological manifestations of sepsis. On the other hand, administration of the S1R inhibitor BD1047 exacerbated the mitochondrial oxidative stress, and apoptosis, as well as symptoms and pathological manifestations of sepsis. In addition, we found that up-regulation of S1R activated the Nrf2/HO1 signaling pathway and promoted nuclear translocation of Nrf2, which activated downstream proteins to generate antioxidant factors, such as HO1, in turn alleviating oxidative stress and countering myocardial damage. ConclusionBy scavenging ROS accumulation and reducing mitochondrial oxidative stress via the Nrf2/HO1 signaling pathway, activation of S1R improves cardiac function, mitigates death of cardiomyocytes, and attenuates sepsis-induced myocardial injury.

Mitochondrial oxidative stress, mitochondrial ROS storms in long COVID pathogenesis.

This review discusses the coronavirus disease 2019 (COVID-19) pathophysiology in the context of diabetes and intracellular reactions by COVID-19, including mitochondrial oxidative stress storms, mitochondrial ROS storms, and long COVID. The long COVID is suffered in ~10% of the COVID-19 patients. Even the virus does not exist, the patients suffer the long COVID for even over a year, This disease could be a mitochondria dysregulation disease. Patients who recover from COVID-19 can develop new or persistent symptoms of multi-organ complications lasting weeks or months, called long COVID. The underlying mechanisms involved in the long COVID is still unclear. Once the symptoms of long COVID persist, they cause significant damage, leading to numerous, persistent symptoms. A comprehensive map of the stages and pathogenetic mechanisms related to long COVID and effective drugs to treat and prevent it are required, which will aid the development of future long COVID treatments and symptom relief.

Neuro-Restorative Effect of Nimodipine and Calcitriol in 1-Methyl 4-Phenyl 1,2,3,6 Tetrahydropyridine-Induced Zebrafish Parkinson's Disease Model.

Parkinson's disease (PD) is one of the most prevalent neurodegenerative diseases, characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. The treatment of PD aims to alleviate motor symptoms by replacing the reduced endogenous dopamine. Currently, there are no disease-modifying agents for the treatment of PD. Zebrafish (Danio rerio) have emerged as an effective tool for new drug discovery and screening in the age of translational research. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is known to cause a similar loss of dopaminergic neurons in the human midbrain, with corresponding Parkinsonian symptoms. L-type calcium channels (LTCCs) have been implicated in the generation of mitochondrial oxidative stress, which underlies the pathogenesis of Parkinson's disease. Therefore, we investigated the neuro-restorative effect of LTCC inhibition in an MPTP-induced zebrafish PD model and suggested a possible drug candidate that might modify the progression of PD. All experiments were conducted using a line of transgenic zebrafish, Tg (dat:EGFP), in which green fluorescent protein (GFP) is expressed in dopaminergic neurons. The experimental groups were exposed to 500µ㏖ MPTP from 1 to 3 days post fertilization (dpf). The drug candidates: Levodopa 1m㏖, Nifedipine 10µ㏖, Nimodipine 3.5 µ㏖, Diethylstilbestrol 0.3 µ㏖, Luteolin 100 µ㏖, Cacitriol 0.25 µ㏖ were exposed from 3 to 5 dpf. Locomotor activity was assessed by automated tracking and dopaminergic neurons were visualized in vivo by confocal microscopy. Levodopa, Nimodipine, Diethylstilbestrol, and Calcitriol had significant positive effects on the restoration of motor behavior, which was damaged by MPTP. Nimodipine and Calcitriol have significant positive effects on the restoration of dopaminergic neurons, which were reduced by MPTP. Through locomotor analysis and dopaminergic neuron quantification, we identified the neuro-restorative effects of Nimodipine and Calcitriol in Zebrafish MPTP-induced PD model. The present study identified the neuro-restorative effects of nimodipine and calcitriol in an MPTP-induced zebrafish model of Parkinson's disease. They restored dopaminergic neurons which were damaged due to the effects of MPTP and normalized the locomotor activity. LTCCs have potential pathological roles in neurodevelopmental and neurodegenerative disorders. Zebrafish are highly amenable to high-throughput drug screening and might, therefore, be a useful tool to work towards the identification of disease-modifying treatment for PD. Further studies including zebrafish genetic models to elucidate the mechanism of action of the disease-modifying candidate by investigating Ca2+ influx and mitochondrial function in dopaminergic neurons, are needed to reveal the pathogenesis of PD and develop disease-modifying treatments for PD.

Importance of Exercise in Mitigating Age-Related Cardiac Apoptosis

Aging causes a progressive decline in heart function. Loss of cardiomyocytes through programmed cell death or apoptosis is a critical factor contributing to this age-related damage. As we age, the heart undergoes structural changes, such as loss of cardiomyocytes, cardiomyocyte hypertrophy, and increased connective tissue with changes in heart geometry. It is widely known that mitochondria are vital sites of apoptosis. Mitochondrial-mediated apoptotic pathways are important regulators of apoptosis with aging. Mitochondrial dysfunction and oxidative stress also contribute to the cardiac remodeling and apoptosis associated with the aging process. On the other hand, exercise can improve heart function and reduce the risk of heart disease. Recent studies suggest that aging increases apoptotic signaling in the left ventricle. However, chronic exercise reduces this mitochondrial-mediated apoptotic signaling pathway in the aging heart. This review will describe the impacts of aging and exercise on cardiac apoptosis, highlighting the importance of exercise in reducing age-related cardiac apoptosis.

Low-Se Diet Increased Mitochondrial ROS to Suppress Myoblasts Proliferation and Promote Apoptosis in Broilers via miR-365-3p/SelT Signaling Axis.

microRNA (miRNA) controls the post-transcriptional translation of mRNA to affect the expression of many genes participating in functional interaction pathways. Selenoproteins are characterized by their antioxidant activity, wherein selenoprotein T (SelT) is an essential membrane-bound selenoprotein serving as a guardian of intracellular homeostasis. During muscle development and regeneration, myoblasts enter the cell cycle and rapidly proliferate. However, the role of SelT in muscle development and selenium (Se) deficiency-induced muscle damage remains poorly investigated. This study established Se deficient broiler models, chicken embryos models, and cultured chicken primary myoblasts in vitro. We showed that Se deficiency induced skeletal muscle damage in broilers, promoted miR-365-3p expression, and downregulated the level of SelT, significantly. The absence of SelT led to the accumulation of mitochondrial superoxide and downregulated mitochondrial dynamics gene expression, which, in turn, induced the disruption of mitochondria potential and blocked the oxidative phosphorylation (OXPHOS) process. Limited ATP production rate caused by mitochondrial ROS overproduction went along with cell cycle arrest, cell proliferation slowness, and myocyte apoptosis increase. Using Mito-TEMPO for mitochondrial ROS elimination could effectively mitigate the above adverse reactions and significantly restore the proliferation potential of myoblasts. Moreover, we identified miR-365-3p, a miRNA that targeted SelT mRNA to inhibit myoblast proliferation by disrupting intracellular redox balance. The omics analysis results showed that Se deficiency led to the significant enrichment of "cell cycle", "oxidative stress response", and "oxidative phosphorylation" pathway genes. Finally, we proved that the effect of the miR-365-3p/SelT signaling axis on muscle development did exist in the chicken embryo stage. In summary, our findings revealed that miR-365-3p was involved in broiler skeletal muscle damage in Se deficiency by targeting SelT, and SelT, serving as an intracellular homeostasis guardian, resisted mitochondrial oxidative stress, and protected ATP generation, promoting myoblast proliferation and inhibiting apoptosis. This study provides an attractive target for the cultivated meat industry and regenerative medicine.

Empagliflozin ameliorates diabetic cardiomyopathy probably via activating AMPK/PGC-1α and inhibiting the RhoA/ROCK pathway.

Diabetic cardiomyopathy (DCM) increases the risk of hospitalization for heart failure (HF) and mortality in patients with diabetes mellitus. However, no specific therapy to delay the progression of DCM has been identified. Mitochondrial dysfunction, oxidative stress, inflammation, and calcium handling imbalance play a crucial role in the pathological processes of DCM, ultimately leading to cardiomyocyte apoptosis and cardiac dysfunctions. Empagliflozin, a novel glucose-lowering agent, has been confirmed to reduce the risk of hospitalization for HF in diabetic patients. Nevertheless, the molecular mechanisms by which this agent provides cardioprotection remain unclear. To investigate the effects of empagliflozin on high glucose (HG)-induced oxidative stress and cardiomyocyte apoptosis and the underlying molecular mechanism. Twelve-week-old db/db mice and primary cardiomyocytes from neonatal rats stimulated with HG (30 mmol/L) were separately employed as in vivo and in vitro models. Echocardiography was used to evaluate cardiac function. Flow cytometry and TdT-mediated dUTP-biotin nick end labeling staining were used to assess apoptosis in myocardial cells. Mitochondrial function was assessed by cellular ATP levels and changes in mitochondrial membrane potential. Furthermore, intracellular reactive oxygen species production and superoxide dismutase activity were analyzed. Real-time quantitative PCR was used to analyze Bax and Bcl-2 mRNA expression. Western blot analysis was used to measure the phosphorylation of AMP-activated protein kinase (AMPK) and myosin phosphatase target subunit 1 (MYPT1), as well as the peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and active caspase-3 protein levels. In the in vivo experiment, db/db mice developed DCM. However, the treatment of db/db mice with empagliflozin (10 mg/kg/d) for 8 wk substantially enhanced cardiac function and significantly reduced myocardial apoptosis, accompanied by an increase in the phosphorylation of AMPK and PGC-1α protein levels, as well as a decrease in the phosphorylation of MYPT1 in the heart. In the in vitro experiment, the findings indicate that treatment of cardiomyocytes with empagliflozin (10 μM) or fasudil (FA) (a ROCK inhibitor, 100 μM) or overexpression of PGC-1α significantly attenuated HG-induced mitochondrial injury, oxidative stress, and cardiomyocyte apoptosis. However, the above effects were partly reversed by the addition of compound C (CC). In cells exposed to HG, empagliflozin treatment increased the protein levels of p-AMPK and PGC-1α protein while decreasing phosphorylated MYPT1 levels, and these changes were mitigated by the addition of CC. Adding FA and overexpressing PGC-1α in cells exposed to HG substantially increased PGC-1α protein levels. In addition, no sodium-glucose cotransporter (SGLT)2 protein expression was detected in cardiomyocytes. Empagliflozin partially achieves anti-oxidative stress and anti-apoptotic effects on cardiomyocytes under HG conditions by activating AMPK/PGC-1α and suppressing of the RhoA/ROCK pathway independent of SGLT2.

Pathological correlates of cognitive decline in Parkinson’s disease: from molecules to neural networks

Parkinson’s disease (PD) is a progressive neurodegenerative disorder resulting from the death of dopaminergic neurons in the substantia nigra and the appearance of protein aggregates in neuronal cell bodies composed predominantly of alpha-synuclein, known as Lewy bodies. PD is now recognized as a multisystem disorder characterized by severe motor impairment and various non-motor symptoms. Cognitive decline is one of the most common and worrisome non-motor symptoms. Moderate cognitive impairment (CI), diagnosed already in the early stages of PD, usually leads to deep dementia. The main types of CI observed in PD include executive dysfunction, attention, and memory disfunction, visuospatial decline, and verbal deficits. According to the literature, the following mechanisms play a significant role in the development of cognitive dysfunctions in PD: (1) changes in the conformational structure of synaptic proteins; (2) disruption of synaptic transmission; (3) neuroinflammation (pathological activation of neuroglia); (4) mitochondrial dysfunction and oxidative stress; (5) metabolic conditions; (6) functional remodeling of the neural networks. The listed molecular and synaptic changes in the brain can lead to the death of dopamine-synthesizing cells of the substantia nigra and dysfunction of other mediator systems, as well as partial cellular atrophy in the neocortex and subcortical nuclei. As a result, the functioning of neural networks involved in the transmission of information related to the regulation of motor activity and cognitive functions is disrupted. Elucidation of the causes of changes occurring in PD and the search for methods to eliminate them will help create new approaches in the treatment of this disease. The aim of the review is to analyze the pathological processes in the brain that underlie the onset of cognitive impairment in PD. The review analyzes the data obtained both from studies on patients with PD and animal (rodents and primates) models of this disease used for the evaluation of the mechanisms underlying etiology and the development of PD in humans.

ApoA-I Protects Pancreatic β-Cells From Cholesterol-Induced Mitochondrial Damage and Restores Their Ability to Secrete Insulin.

High cholesterol levels in pancreatic β-cells cause oxidative stress and decrease insulin secretion. β-cells can internalize apo (apolipoprotein) A-I, which increases insulin secretion. This study asks whether internalization of apoA-I improves β-cell insulin secretion by reducing oxidative stress. Ins-1E cells were cholesterol-loaded by incubation with cholesterol-methyl-β-cyclodextrin. Insulin secretion in the presence of 2.8 or 25 mmol/L glucose was quantified by radioimmunoassay. Internalization of fluorescently labeled apoA-I by β-cells was monitored by flow cytometry. The effects of apoA-I internalization on β-cell gene expression were evaluated by RNA sequencing. ApoA-I-binding partners on the β-cell surface were identified by mass spectrometry. Mitochondrial oxidative stress was quantified in β-cells and isolated islets with MitoSOX and confocal microscopy. An F1-ATPase β-subunit on the β-cell surface was identified as the main apoA-I-binding partner. β-cell internalization of apoA-I was time-, concentration-, temperature-, cholesterol-, and F1-ATPase β-subunit-dependent. β-cells with internalized apoA-I (apoA-I+ cells) had higher cholesterol and cell surface F1-ATPase β-subunit levels than β-cells without internalized apoA-I (apoA-I- cells). The internalized apoA-I colocalized with mitochondria and was associated with reduced oxidative stress and increased insulin secretion. The IF1 (ATPase inhibitory factor 1) attenuated apoA-I internalization and increased oxidative stress in Ins-1E β-cells and isolated mouse islets. Differentially expressed genes in apoA-I+ and apoA-I- Ins-1E cells were related to protein synthesis, the unfolded protein response, insulin secretion, and mitochondrial function. These results establish that β-cells are functionally heterogeneous, and apoA-I restores insulin secretion in β-cells with elevated cholesterol levels by improving mitochondrial redox balance.

Differential Effects of Paraquat, Rotenone, and MPTP on Cellular Bioenergetics of Undifferentiated and Differentiated Human Neuroblastoma Cells.

Paraquat (PQ), rotenone (RO), and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) are neurotoxicants that can damage human health. Exposure to these neurotoxicants has been linked to neurodegeneration, particularly Parkinson's disease. However, their mechanisms of action have not been fully elucidated, nor has the relative vulnerability of neuronal subtypes to their exposures. To address this, the current study investigated the cytotoxic effects of PQ, RO, and MPTP and their relative effects on cellular bioenergetics and oxidative stress on undifferentiated human neuroblastoma (SH-SY5Y) cells and those differentiated to dopaminergic (DA) or cholinergic (CH) phenotypes. The tested neurotoxicants were all cytotoxic to the three cell phenotypes that correlated with both concentration and exposure duration. At half-maximal effective concentrations (EC50s), there were significant reductions in cellular ATP levels and reduced activity of the mitochondrial complexes I and III, with a parallel increase in lactate production. PQ at 10 µM significantly decreased ATP production and mitochondrial complex III activity only in DA cells. RO was the most potent inhibitor of mitochondrial complex 1 and did not inhibit mitochondrial complex III even at concentrations that induced a 50% loss of cell viability. MPTP was the most potent toxicant in undifferentiated cells. All neurotoxicants significantly increased reactive oxygen species, lipid peroxidation, and nuclear expression of Nrf2, with a corresponding inhibition of the antioxidant enzymes catalase and superoxide dismutase. At a 10 µM exposure to PQ or RO, oxidative stress biomarkers were significant in DA cells. Collectively, this study underscores the importance of mitochondrial dysfunction and oxidative stress in PQ, RO, and MPTP-induced cytotoxicity and that neuronal phenotypes display differential vulnerability to these neurotoxicants.

Valine improves mitochondrial function and protects against oxidative stress.

Among the branched-chain amino acids, leucine and isoleucine have been well studied for their roles in improving mitochondrial function and reducing oxidative stress. However, role of valine in mitochondrial function regulation and oxidative stress management remains elusive. This study investigated valine effect on mitochondrial function and oxidative stress in vitro. Valine increased expression of genes involved in mitochondrial biogenesis and dynamics. It upregulates mitochondrial function at complexes I, II, and IV levels of electron transport chain. Flow cytometry studies revealed, valine reduced oxidative stress by significantly lowering mitochondrial reactive oxygen species and protein expression of 4-hydroxynonenal. Functional role of valine against oxidative stress was analyzed by XFe96 Analyzer. Valine sustained oxidative phosphorylation and improved ATP generation rates during oxidative stress. In conclusion, our findings shed more light on the critical function of valine in protecting mitochondrial function thereby preventing mitochondrial/cellular damage induced by oxidative stress.

Curcumin-ZnO conjugated nanoparticles confer neuroprotection against ketamine-induced neurotoxicity.

Nanotechnology and its application to manipulate herbal compounds to design new neuroprotective agents to manage neurotoxicity has recently increased. Cur-ZnO conjugated nanoparticles were synthesized and used in an experimental model of ketamine-induced neurotoxicity. Cur-ZnO conjugated nanoparticles were chemically characterized, and the average crystalline size was determined. Forty-nine adult mice were divided into seven groups of seven animals each. Normal saline was given to control mice (group 1). Ketamine (25 mg/kg) was given to a second group. A third group of mice was given ketamine (25 mg/kg) in combination with curcumin (40 mg/kg), while mice in groups 4, 5, and 6 received ketamine (25 mg/kg) plus Cur-ZnO nanoparticles (10, 20, and 40 mg/kg). Group 7 received only ZnO (5 mg/kg). All doses were ip for 14 days. Hippocampal mitochondrial quadruple complex enzymes, oxidative stress, inflammation, and apoptotic characteristics were assessed. Cur-ZnO nanoparticles and curcumin decreased lipid peroxidation, GSSG content, IL-1β, TNF-α, and Bax levels while increasing GSH and antioxidant enzymes like GPx, GR, and SOD while increasing Bcl-2 level and mitochondrial quadruple complex enzymes in ketamine treatment groups. The neuroprotective properties of Cur-ZnO nanoparticles were efficient in preventing ketamine-induced neurotoxicity in the mouse brain. The nanoparticle form of curcumin (Cur-ZnO) required lower doses to produce neuroprotective effects against ketamine-induced toxicity than conventional curcumin.

Association between plasma L-carnitine levels and mitochondrial DNA copy number

Mitochondria are key cytoplasmic organelles in eukaryotic cells that generate adenosine triphosphate (ATP) through the electron transport chain and oxidative phosphorylation. Mitochondrial DNA (mtDNA) copy number (mtDNAcn) is considered a biomarker for both mitochondrial quantity and function as well as cellular oxidative stress level. Previous epidemiologic findings revealed that weight gain, higher body mass index (BMI), smoking, and high insulinemic potential of lifestyle were associated with lower leukocyte mtDNAcn. Carnitines are a group of compounds that play a critical role in energy production. We quantified the associations of plasma L-carnitine levels with leukocyte mtDNAcn. We then examined the association between mtDNAcn and L-carnitine (HMDB0000062) in 538 U.S. men without cancers, diabetes, or cardiovascular disease at blood collection from the Health Professionals Follow-Up Study (HPFS). We found a significant inverse association between L-carnitine and mtDNAcn (ρ = −0.1, P = 0.02). This implies that the carnitine metabolic pathway may be associated with mitochondrial function and oxidative stress.

Engineering “Trojan Horse” disguised by cancer cell membranes for mitochondrial targeting and amplified immunotherapy

As the most promising strategy for cancer treatment, immunotherapy has attracted much attention, but its treatment effect is still blocked by the deficient immune response efficiency. In light of the significant role of mitochondria in cell metabolism, it has been considered to be a promising target to amplify immune response. In this report, a mitochondria-targeted nanodrug (UCNP@COF@FeCO/TPP@CM, UCFT@CM), camouflaged by cancer cell membrane (CM), was designed to realize cascade target and enhance immune response, further achieving the synergistic therapy of photodynamic therapy (PDT), CO gas therapy and immunotherapy. With the assistance of CM, the nanodrug exhibited significant enhancement on homologous targeting. After endocytosis, UCFT@CM would accumulate in mitochondria and realize controlled release of CO and enhanced PDT relying on the characteristics of mitochondria, further leading to serious mitochondrial oxidative stress and amplified immunotherapy. In addition, we verified that a new immune signal related to mitochondrial oxidative stress, mitochondrial transcription factor A (TFAM), is strongly associated with immunogenic cell death (ICD). Taken together, the sequenced targeting treatment makes full use of characteristics of mitochondria and provides a new approach for precisely targeting organelle to enhance the immune response.

Nrf2 protects against cartilage endplate degeneration through inhibiting NCOA4‑mediated ferritinophagy.

Iron overload and ferroptosis are associated with intervertebral disc degeneration (IDD); however, the mechanism underlying the regulation of iron homeostasis remains to be elucidated. Nuclear factor erythroid 2‑related factor 2 (Nrf2) has been reported to regulate cellular iron homeostasis; however, its impact on IDD pathology and the underlying mechanism of action requires further investigation. In the present study, immunohistochemistry analysis of Nrf2 expression in the cartilage endplate (CEP) was conducted and it was demonstrated that Nrf2 expression was increased in the CEP at the early stages of the development of IDD, whereas it was decreased at the late stages of the development of IDD. The results of western blot analysis indicated that the inadequate activation of Nrf2 may aggravate mitochondrial dysfunction and oxidative stress, thus promoting CEP chondrocyte degeneration and calcification. It was also revealed that Nrf2 was involved in TNF‑α‑induced CEP chondrocyte iron metabolism dysfunction and ferroptosis. Inhibition of Nrf2 expression using Nrf2 small interfering RNA could enhance the process of nuclear receptor coactivator 4 (NCOA4)‑mediated ferritinophagy and increase ferrous ion content, which may promote CEP chondrocyte ferroptotic cell death and extracellular matrix degradation. Furthermore, a decrease in cellular iron concentration may inhibit CEP chondrocyte ferroptosis, and CEP degeneration and calcification. The present study highlights the role of the Nrf2/NCOA4 axis in chondrocyte ferroptosis and IDD pathogenesis, thus suggesting that activation of Nrf2 may be a promising strategy for IDD treatment.

Mitochondria- and NOX4-dependent antioxidant defense mitigates progression to nonalcoholic steatohepatitis in obesity.

Nonalcoholic fatty liver disease (NAFLD) is prevalent in the majority of individuals with obesity, but in a subset of these individuals, it progresses to nonalcoholic steatohepatitis (0NASH) and fibrosis. The mechanisms that prevent NASH and fibrosis in the majority of patients with NAFLD remain unclear. Here, we report that NAD(P)H oxidase 4 (NOX4) and nuclear factor erythroid 2-related factor 2 (NFE2L2) were elevated in hepatocytes early in disease progression to prevent NASH and fibrosis. Mitochondria-derived ROS activated NFE2L2 to induce the expression of NOX4, which in turn generated H2O2 to exacerbate the NFE2L2 antioxidant defense response. The deletion or inhibition of NOX4 in hepatocytes decreased ROS and attenuated antioxidant defense to promote mitochondrial oxidative stress, damage proteins and lipids, diminish insulin signaling, and promote cell death upon oxidant challenge. Hepatocyte NOX4 deletion in high-fat diet-fed obese mice, which otherwise develop steatosis, but not NASH, resulted in hepatic oxidative damage, inflammation, and T cell recruitment to drive NASH and fibrosis, whereas NOX4 overexpression tempered the development of NASH and fibrosis in mice fed a NASH-promoting diet. Thus, mitochondria- and NOX4-derived ROS function in concert to drive a NFE2L2 antioxidant defense response to attenuate oxidative liver damage and progression to NASH and fibrosis in obesity.

HACE1 expression in heart failure patients might promote mitochondrial oxidative stress and ferroptosis by targeting NRF2.

Heart failure is a prevalent and life-threatening medical condition characterized by abnormal atrial electrical activity, contributing to a higher risk of ischemic stroke. Atrial remodelling, driven by oxidative stress and structural changes, plays a central role in heart failure progression. Recent studies suggest that HACE1, a regulatory gene, may be involved in cardiac protection against heart failure. Clinical data analysis involved heart failure patients, while an animal model utilized C57BL/6J mice. RT-PCR, microarray analysis, histological examination, ELISA, and Western blot assays were employed to assess gene and protein expression, oxidative stress, and cardiac function. Cell transfection and culture of mouse atrial fibroblasts were performed for in-vitro experiments. HACE1 expression was reduced in heart failure patients and correlated negatively with collagen levels. In mouse models, HACE1 up-regulation reduced oxidative stress, mitigated fibrosis, and improved cardiac function. Conversely, HACE1 knockdown exacerbated oxidative stress, fibrosis, and cardiac dysfunction. HACE1 also protected against ferroptosis and mitochondrial damage. NRF2, a transcription factor implicated in oxidative stress, was identified as a target of HACE1, with HACE1 promoting NRF2 activity through ubiquitination. HACE1 emerges as a potential therapeutic target and diagnostic marker for heart failure. It regulates oxidative stress, mitigates cardiac fibrosis, and protects against ferroptosis and mitochondrial damage. The study reveals that HACE1 achieves these effects, at least in part, through NRF2 activation via ubiquitination, offering insights into novel mechanisms for heart failure pathogenesis and potential interventions.

Endoplasmic reticulum stress exacerbates microplastics-induced toxicity in animal cells

Human and animal exposure to microplastics (MPs) contained in food is inevitable because of their widespread existence in the environment. Nevertheless, MPs toxicity studies in ruminants often lack attention. Here, we assessed the cytotoxicity of polystyrene microplastics (PS MPs) on goat mammary epithelial cells (GMECs). Compared to controls, PS MPs treatment significantly reduced cell viability, altered cell morphology and disrupted organelle integrity. Detection of membrane potential and reactive oxygen species (ROS) suggested that PS MPs induced mitochondrial dysfunction and oxidative stress. Further transcriptome analysis also confirmed alterations in these pathways. In addition, several genes related to endoplasmic reticulum (ER) homeostasis were significantly regulated in the transcriptional profile. Subsequent experiments confirmed that PS MPs induce ER stress via the PERK/eIF2α/CHOP pathway, accompanied by intracellular Ca2+ overload. Meanwhile, downstream activation of the Bax/Bcl-2 pathway and caspase cascade released apoptotic signals, which led to apoptosis in GMECs. Interestingly, the addition of PERK inhibitor (ISRIB) attenuated PS MPs-induced ER stress and apoptosis, which suggests that ER stress may exacerbate PS MPs-induced cytotoxicity. This work reveals the impact of MPs on mammalian cytotoxicity, enriches the mechanisms for the toxicity of MPs, and provides insight for further assessment of the risk of MPs in food.

MnO2 nanoparticles trigger hepatic lipotoxicity and mitophagy via mtROS-dependent Hsf1Ser326 phosphorylation

Manganese (Mn) is an essential element for maintaining normal metabolism in vertebrates. Mn dioxide nanoparticles (MnO2 NPs), a novel Mn source, have shown great potentials in biological and biomedical applications due to their distinct physical and chemical properties. However, little is known about potential adverse effects on animal or cellular metabolism. Here, we investigated whether and how dietary MnO2 NPs affect hepatic lipid metabolism in vertebrates. We found that, excessive MnO2 NPs intake increased hepatic and mitochondrial Mn content, promoted hepatic lipotoxic disease and lipogenesis, and inhibited hepatic lipolysis and fatty acid β-oxidation. Moreover, excessive MnO2 NPs intake induced hepatic mitochondrial oxidative stress, damaged mitochondrial function, disrupted mitochondrial dynamics and activated mitophagy. Importantly, we uncovered that mtROS-activated phosphorylation of heat shock factor 1 (Hsf1) at Ser326 residue mediated MnO2 NPs-induced hepatic lipotoxic disease and mitophagy. Mechanistically, MnO2 NPs-induced lipotoxicity and mitophagy were via mtROS-induced phosphorylation and nucleus translocation of Hsf1 and its DNA binding capacity to plin2/dgat1 and bnip3 promoters, respectively. Overall, our findings uncover novel mechanisms by which mtROS-mediated mitochondrial dysfunction and phosphorylation of Hsf1S326 contribute to MnO2 NPs-induced hepatic lipotoxicity and mitophagy, which provide new insights into the effects of metal oxides nanoparticles on hepatotoxicity in vertebrates.

NSC48160 targets AMPKα to ameliorate nonalcoholic steatohepatitis by inhibiting lipogenesis and mitochondrial oxidative stress

Hepatic steatosis, which is triggered by dysregulation of lipid metabolism and redox equilibrium in the liver, is regarded as a risk factor in the non-alcoholic fatty liver disease (NAFLD). However, pharmacologic engagement of this process is difficult. We identified the small molecule NSC48160 as an effective agent against nonalcoholic steatohepatitis (NASH). We found that NSC48160 significantly lowered hepatic lipid levels invitro and invivo by activating the AMPKα-dependent pathway. AMPKα regulated its downstream pathway involved in lipogenesis (SREBP-1c/FASN pathway) and fatty acid oxidation (PPARα pathway). Metabonomics analysis combined with RNA-sequencing profiling revealed that NSC48160-induced lipogenesis is modulated by lipid metabolism. Moreover, NSC48160 dramatically reduces reactive oxygen species (ROS) production, restores the levels of the membrane potential and NAD+/NADH ratio, and improves mitochondrial respiration. These findings suggest that NSC48160 is a promising hit compound in the pursuit of a pharmacological approach in the treatment of NASH.

Pharmacologically targeted mitochondrial fission/fusion performs neuroprotection against trastuzumab‐induced cognitive deficits in rats via suppressing mitochondrial dysfunction and oxidative stress

AbstractBackgroundTrastuzumab (TRZ) has been utilized primarily as a chemotherapeutic treatment for advanced human epidermal growth factor receptor type 2‐expressing malignant tumors. Regardless, TRZ‐associated neurotoxicity has emerged as an adverse clinical complication of oncologic therapy by increasing oxidative stress and damaging mitochondrial function. As the neuroprotective effects of mitochondrial fission inhibitor (MDV) and fusion promoter (M1) have been illustrated for a variety of neurological pathologies, the anti‐neurotoxic mechanisms of MDV and M1 against TRZ are unknown.MethodTwenty male Wistar rats were randomly divided into either the TRZ group (4 mg/kg/day for 7 days, I.P., n = 15) or the control group (CON, n = 5). In the TRZ group, rats also received one of the following co‐treatments: 1) vehicle (VEH, n = 5), 2) MDV (1.2 mg/kg/day, n = 5), or 3) M1 (2 mg/kg/day, n = 5) via I.P. injection for 7 days. Subsequently, novel object location (NOL) and novel object recognition (NOR) tests for long‐term learning and memory were performed. Then, the brain tissue was used for determining mitochondrial functions, and the blood serum was also used to measure the oxidative stress levels.ResultTRZ (the VEH group) increased brain mitochondrial dysfunction and systemic oxidative stress via increasing reactive oxygen species (ROS) production, mitochondrial depolarization, mitochondrial swelling, and serum malondialdehyde levels, respectively, when compared to the CON group (p<0.05, Figure 1). TRZ (the VEH group) impaired long‐term learning and memory, as indicated by the attenuated percentage preference index of NOL and NOR tests, compared to the CON group (p<0.05, Figure 1). MDV and M1 co‐therapies exerted neuroprotection by rescuing brain mitochondrial function and systemic oxidative stress, resulting in the restoration of long‐term cognitive parameters (p<0.05, Figure 1).ConclusionTargeting brain mitochondrial dynamics could be an effective remedy against TRZ‐induced cognitive impairment in rats via suppressing mitochondrial dysfunction and oxidative stress. Therefore, pharmacological inhibition of mitochondrial fission and promotion of mitochondrial fusion could be a novel anti‐neurotoxicity‐induced by TRZ.