Rupture Of Mitochondrial Membrane Research Articles

Apoptosis and Oxidative Stress in Human Intestinal Epithelial Caco-2 Cells Caused by Marine Phycotoxin Azaspiracid-2.

When humans consume seafood contaminated by lipophilic polyether phycotoxins, such as azaspiracids (AZAs), the toxins are mainly leached and absorbed in the small intestine, potentially causing intestinal damage. In this study, human intestinal epithelial Caco-2 cells were used to investigate the adverse effects of azaspiracid-2 (AZA-2) on human intestinal epithelial cells. Cell viability, apoptosis, oxidative damage and mitochondrial ultrastructure were investigated, and ribonucleic acid sequence (RNA-seq) analysis was applied to explore the potential mechanisms of AZA-2 toxicity to Caco-2 cells. Results showed that AZA-2 significantly reduced the proliferation of Caco-2 cells in a concentration-dependent response, and the 48 h EC50 of AZA-2 was 12.65 nmol L-1. AZA-2 can induce apoptosis in Caco-2 cells in a dose-dependent manner. Visible mitochondrial swelling, cristae disintegration, membrane rupture and autophagy were observed in Caco-2 cells exposed to AZA-2. Reactive oxygen species (ROS) and malondialdehyde (MDA) content were significantly increased in Caco-2 cells after 48 h of exposure to 1 and 10 nmol L-1 of AZA-2. Transcriptome analysis showed that KEGG pathways related to cellular oxidative damage and lipid metabolism were affected, mainly including mitophagy, oxidative phosphorylation, cholesterol metabolism, vitamin digestion and absorption, bile secretion and the peroxisome proliferator-activated receptor signaling pathway. The cytotoxic effects of AZA-2 on Caco-2 cells may be associated with ROS-mediated autophagy and apoptosis in mitochondrial cells. Results of this study improve understanding of the cytotoxicity and molecular mechanisms of AZA-2 on Caco-2 cells, which is significant for protecting human health.

Fluorescence Lifetime Super-Resolution Imaging Unveil the Dynamic Relationship between Mitochondrial Membrane Potential and Cristae Structure Using the Förster Resonance Energy Transfer Strategy.

Mitochondrial cristae, invaginations of the inner mitochondrial membrane (IMM) into the matrix, are the main site for the generation of ATP via oxidative phosphorylation, and mitochondrial membrane potential (MMP). Synchronous study of the dynamic relationship between cristae and MMP is very important for further understanding of mitochondrial function. Due to the lack of suitable IMM probes and imaging techniques, the dynamic relationship between MMP and cristae structure alterations remains poorly understood. We designed a pair of FRET-based molecular probes, with the donor (OR-LA) being rhodamine modified with mitochondrial coenzyme lipoic acid and the acceptor (SiR-BA) being silicon-rhodamine modified with a butyl chain, for simultaneous dynamic monitoring of mitochondrial cristae structure and MMP. The FRET process of the molecular pair in mitochondria is regulated by MMP, enabling more precise visualization of MMP through fluorescence intensity ratio and fluorescence lifetime. By combining FRET with FLIM super-resolution imaging technology, we achieved simultaneous dynamic monitoring of mitochondrial cristae structure and MMP, revealing that during the decline of MMP, there is a progression involving cristae dilation, fragmentation, mitochondrial vacuolization, and eventual rupture. Significantly, we successfully observed that the rapid decrease in MMP at the site of mitochondrial membrane rupture may be a critical factor in mitochondrial fragmentation. These data collectively reveal the dynamic relationship between cristae structural alterations and MMP decline, laying a foundation for further investigation into cellular energy regulation mechanisms and therapeutic strategies for mitochondria-related diseases.

Mitochondrial GPX4 acetylation is involved in cadmium-induced renal cell ferroptosis

Increasing evidences demonstrate that environmental stressors are important inducers of acute kidney injury (AKI). This study aimed to investigate the impact of exposure to Cd, an environmental stressor, on renal cell ferroptosis. Transcriptomics analyses showed that arachidonic acid (ARA) metabolic pathway was disrupted in Cd-exposed mouse kidneys. Targeted metabolomics showed that renal oxidized ARA metabolites were increased in Cd-exposed mice. Renal 4-HNE, MDA, and ACSL4, were upregulated in Cd-exposed mouse kidneys. Consistent with animal experiments, the in vitro experiments showed that mitochondrial oxidized lipids were elevated in Cd-exposed HK-2 cells. Ultrastructure showed mitochondrial membrane rupture in Cd-exposed mouse kidneys. Mitochondrial cristae were accordingly reduced in Cd-exposed mouse kidneys. Mitochondrial SIRT3, an NAD+-dependent deacetylase that regulates mitochondrial protein stability, was reduced in Cd-exposed mouse kidneys. Subsequently, mitochondrial GPX4 acetylation was elevated and mitochondrial GPX4 protein was reduced in Cd-exposed mouse kidneys. Interestingly, Cd-induced mitochondrial GPX4 acetylation and renal cell ferroptosis were exacerbated in Sirt3−/− mice. Conversely, Cd-induced mitochondrial oxidized lipids were attenuated in nicotinamide mononucleotide (NMN)-pretreated HK-2 cells. Moreover, Cd-evoked mitochondrial GPX4 acetylation and renal cell ferroptosis were alleviated in NMN-pretreated mouse kidneys. These results suggest that mitochondrial GPX4 acetylation, probably caused by SIRT3 downregulation, is involved in Cd-evoked renal cell ferroptosis.

In situ profiling reveals spatially metabolic injury in the initiation of polystyrene nanoplastic-derived intestinal epithelial injury in mice

Despite increasing concerns regarding the harmful effects of plastic-induced gut injury, mechanisms underlying the initiation of plastic-derived intestinal toxicity remain unelucidated. Here, mice were subjected to long-term exposure to polystyrene nanoplastics (PS-NPs) of varying sizes (80, 200, and 1000 nm) at doses relevant to human dietary exposure. PS-NPs exposure did not induce a significant inflammatory response, histopathological damage, or intestinal epithelial dysfunction in mice at a dosage of 0.5 mg/kg/day for 28 days. However, PS-NPs were detected in the mouse intestine, coupled with observed microstructural changes in enterocytes, including mild villous lodging, mitochondrial membrane rupture, and endoplasmic reticulum (ER) dysfunction, suggesting that intestinal-accumulating PS-NPs resulted in the onset of intestinal epithelial injury in mice. Mechanistically, intragastric PS-NPs induced gut microbiota dysbiosis and specific bacteria alterations, accompanied by abnormal metabolic fingerprinting in the plasma. Furthermore, integrated data from mass spectrometry imaging-based spatial metabolomics and metallomics revealed that PS-NPs exposure led to gut dysbiosis-associated host metabolic reprogramming and initiated intestinal injury. These findings provide novel insights into the critical gut microbial-host metabolic remodeling events vital to nanoplastic-derived-initiated intestinal injury.

Environmental Evaluation on Toxicity, Toxic Mechanism, and Hydrolysis Behavior of Potential Acethydrazide Fungicide Candidates.

The evaluation of toxicity and environmental behavior of bioactive lead molecules is helpful in providing theoretical support for the development of agrochemicals, in line with the sustainable development of the ecological environment. In previous work, some acethydrazide structures have been demonstrated to exhibit excellent and broad-spectrum fungicidal activity; however, its environmental compatibility needs to be further elucidated if it is to be identified as a potential fungicide. In this project, the toxicity of fungicidal acethydrazide lead compounds F51, F58, F72, and F75 to zebrafish was determined at 10 μg mL-1 and 1 μg mL-1. Subsequently, the toxic mechanism of compound F58 was preliminarily explored by histologic section and TEM observations, which revealed that the gallbladder volume of common carp treated with compound F58 increased, accompanied by a deepened bile color, damaged plasma membrane, and atrophied mitochondria in gallbladder cells. Approximately, F58-treated hepatocytes exhibited cytoplasmic heterogeneity, with partial cellular vacuolation and mitochondrial membrane rupture. Metabolomics analysis further indicated that differential metabolites were enriched in the bile formation-associated steroid biosynthesis, primary bile acid biosynthesis, and taurine and hypotaurine metabolism pathways, as well as in the membrane function-related glycerophospholipid metabolism, linolenic acid metabolism, α-linolenic acid metabolism, and arachidonic acid metabolism pathways, suggesting that the acethydrazide F58 may have acute liver toxicity to common carp. Finally, the hydrolysis dynamics of F58 was investigated, with the obtained half-life of 5.82 days. The above results provide important guiding significance for the development of new green fungicides.

UBQLN2 and HSP70 participate in Parkin-mediated mitophagy by facilitating outer mitochondrial membrane rupture.

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are two aging-related neurodegenerative diseases that share common key features, including aggregation of pathogenic proteins, dysfunction of mitochondria, and impairment of autophagy. Mutations in ubiquilin 2 (UBQLN2), a shuttle protein in the ubiquitin-proteasome system (UPS), can cause ALS/FTD, but the mechanism underlying UBQLN2-mediated pathogenesis is still uncertain. Recent studies indicate that mitophagy, a selective form of autophagy which is crucial for mitochondrial quality control, is tightly associated with neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and ALS. In this study, we show that after Parkin-dependent ubiquitination of damaged mitochondria, UBQLN2 is recruited to poly-ubiquitinated mitochondria through the UBA domain. UBQLN2 cooperates with the chaperone HSP70 to promote UPS-driven degradation of outer mitochondrial membrane (OMM) proteins. The resulting rupture of the OMM triggers the autophagosomal recognition of the inner mitochondrial membrane receptor PHB2. UBQLN2 is required for Parkin-mediated mitophagy and neuronal survival upon mitochondrial damage, and the ALS/FTD pathogenic mutations in UBQLN2 impair mitophagy in primary cultured neurons. Taken together, our findings link dysfunctional mitophagy to UBQLN2-mediated neurodegeneration.

Fucoidan Ameliorates Ferroptosis in Ischemia-reperfusion-induced Liver Injury through Nrf2/HO-1/GPX4 Activation.

Liver ischemia-reperfusion (IR) injury is a common pathological process in liver surgery. Ferroptosis, which is closely related to lipid peroxidation, has recently been confirmed to be involved in the pathogenesis of IR injury. However, the development of drugs that regulate ferroptosis has been slow, and a complete understanding of the mechanisms underlying ferroptosis has not yet been achieved. Fucoidan (Fu) is a sulfated polysaccharide that has attracted research interest due to its advantages of easy access and wide biological activity. In this study, we established models of IR injury using erastin as an activator of ferroptosis, with the ferroptosis inhibitor ferrostatin-1 (Fer-1) as the control. We clarified the molecular mechanism of fucoidan in IR-induced ferroptosis by determining lipid peroxidation levels, mitochondrial morphology, and key pathways in theta were involved. Ferroptosis was closely related to IR-induced hepatocyte injury. The use of fucoidan or Fer-1 inhibited ferroptosis by eliminating reactive oxygen species and inhibiting lipid peroxidation and iron accumulation, while those effects were reversed after treatment with erastin. Iron accumulation, mitochondrial membrane rupture, and active oxygen generation related to ferroptosis also inhibited the entry of nuclear factor erythroid 2-related factor 2 (Nrf2) into the nucleus and reduced downstream heme oxygenase-1 (HO-1) and glutathione peroxidase 4 (GPX4) protein levels. However, fucoidan pretreatment produced adaptive changes that reduced irreversible cell damage induced by IR or erastin. Fucoidan inhibited ferroptosis in liver IR injury via the Nrf2/HO-1/GPX4 axis.

The histone deacetylase inhibitor SAHA exerts a protective effect against myocardial ischemia/reperfusion injury by inhibiting sodium-calcium exchanger

Calcium overload performs a crucial function in the pathogenesis of myocardial ischemia-reperfusion (I/R) damage, which contributes to mitochondrial impairment and apoptosis of cardiomyocytes. Suberoylanilide hydroxamic acid (SAHA), a small molecule histone deacetylases inhibitor with modulatory capacity on Na+-Ca2+ exchanger (NCX), is proven to have protective potential towards cardiac remodeling and injury, but the mechanism remains unclear. Hence, Hence, our present research explored the modulation of NCX-Ca2+-CaMKII by SAHA in myocardial I/R damage. Our outcomes indicate that in vitro hypoxia and reoxygenation models of myocardial cells, SAHA treatment inhibited the increase in expression of NCX1, intracellular Ca2+ concentration, expression of CaMKII and self-phosphorylated CaMKII, and cell apoptosis. In addition, SAHA treatment improved myocardial cell mitochondrial swelling inhibited mitochondrial membrane potential diminution and the openness of the mitochondrial permeability transition pore, and protected against mitochondrial dysfunction following I/R injury. In vivo, SAHA treatment alleviated the decrease in FS% and EF%, the increase in the myocardial infarct area, and myocardial enzyme levels caused by I/R injury, while also reducing myocardial cell apoptosis, and inhibiting mitochondrial fission and mitochondrial membrane rupture. These results indicated that SAHA treatment alleviated myocardial cell apoptosis as well as mitochondrial dysfunction resulting from myocardial I/R impairment, and contributed to myocardial function recovery by inhibiting the NCX-Ca2+-CaMKII pathway. These findings offered additional theoretical support to explore the mechanism of SAHA as a therapeutic agent in cardiac I/R damage and develop new treatment strategies.

Phytosphingosine-induced cell apoptosis via a mitochondrially mediated pathway

Cyanobacterial blooms, usually dominated by Microcystis aeruginosa, pose a serious threat to global freshwater ecosystems owing to their production and release of various harmful secondary metabolites. Detection of the chemicals in M. aeruginosa exudates using metabolomics technology revealed that phytosphingosine (PHS) was one of the most abundant compounds. However, its specific toxicological mechanism remained unclear. CNE-2 cells were selected to illustrate the cytotoxic mechanism of PHS, and it was determined to cause excessive production of reactive oxygen species and subsequently damage the mitochondrial structure. Mitochondrial membrane rupture led to matrix mitochondrial membrane potential disintegration, which induced Ca2+ overload and interrupted ATP synthesis. Furthermore, rupture of the mitochondrial membrane induced the opening of the permeability transition pore, which caused the release of proapoptotic factors into the cytoplasm and the expression of apoptosis-related proteins Bax, Bcl-2, cytochrome-c and cleaved caspase-3 in CNE-2 cells. These events, in turn, activated the mitochondrially mediated intrinsic apoptotic pathway. A mitochondrial repair mechanism, namely, PINK1/Parkin-mediated mitophagy, was then blocked, which further promoted apoptosis. Our findings suggest that more attention should be paid to the ecotoxicity of PHS, which is already listed as a contaminant of emerging concern.

Protective role of curcumin on aflatoxin B1-induced TLR4/RIPK pathway mediated-necroptosis and inflammation in chicken liver

This study set out to assess the mitigative effects of curcumin on AFB1-induced necroptosis and inflammation in chicken liver. Ninety-six one-day-old AA broiler chickens were separated into four groups, including control group, AFB1 (1 mg/kg) group, curcumin (300 mg/kg) + AFB1 (1 mg/kg) group and curcumin (300 mg/kg) group. After 28 days treatment, livers were collected for different experimental analyses. The morphological observation results showed obvious necrotic characteristics, including cell swelling, rupture of cell and mitochondrial membranes and inflammation in chicken livers. AFB1 exposure increased oxidative stress index (ROS and MDA) and decreased the antioxidant activity markers (SOD, CAT and GSH) and ATPase activities in chickens’ liver. ELISA results showed that AFB1 exposure significantly induced the cytokines (TNF-α, iNOS, IL-6 and IL-1β) release from the liver tissues. While, western blot and qRT-PCR results showed that the protein and mRNA expressions of inflammatory (TLR4/myd88/NF-κB) and necroptosis (RIPK1/RIPK3/MLKL) genes were up-regulated by AFB1 exposure. We suspect that signal crosstalk between TLR4 and TNF-α triggers inflammation and RIPK1/RIPK3 mediating necroptosis in AFB1-induced chicken liver injury. Curcumin can regulate the TLR4/RIPK signaling pathway, reduced oxidative stress biomarkers and inflammatory cytokines levels and attenuated the expression of necroptosis and inflammation genes altered by AFB1 to reduce necroptosis of chicken liver tissue. In conclusion, curcumin can protect against AFB1-induced necroptosis and inflammation by TLR4/RIPK pathway in chicken liver.

Gasdermin E mediates photoreceptor damage by all-trans-retinal in the mouse retina

The breakdown of all-trans-retinal (atRAL) clearance is closely associated with photoreceptor cell death in dry age-related macular degeneration (AMD) and autosomal recessive Stargardt's disease (STGD1), but its mechanisms remain elusive. Here, we demonstrate that activation of gasdermin E (GSDME) but not gasdermin D promotes atRAL-induced photoreceptor damage by activating pyroptosis and aggravating apoptosis through a mitochondria-mediated caspase-3-dependent signaling pathway. Activation of c-Jun N-terminal kinase was identified as one of the major causes of mitochondrial membrane rupture in atRAL-loaded photoreceptor cells, resulting in the release of cytochrome c from mitochondria to the cytosol, where it stimulated caspase-3 activation required for cleavage of GSDME. Aggregation of the N-terminal fragment of GSDME in the mitochondria revealed that GSDME was likely to penetrate mitochondrial membranes in photoreceptor cells after atRAL exposure. ABC (subfamily A, member 4) and all-trans-retinol dehydrogenase 8 are two key proteins responsible for clearing atRAL in the retina. Abca4−/−Rdh8−/− mice exhibit serious defects in atRAL clearance upon light exposure and serve as an acute model for dry AMD and STGD1. We found that N-terminal fragment of GSDME was distinctly localized in the photoreceptor outer nuclear layer of light-exposed Abca4−/−Rdh8−/− mice. Of note, degeneration and caspase-3 activation in photoreceptors were significantly alleviated in Abca4−/−Rdh8−/−Gsdme−/− mice after exposure to light. The results of this study indicate that GSDME is a common causative factor of photoreceptor pyroptosis and apoptosis arising from atRAL overload, suggesting that repressing GSDME may represent a potential treatment of photoreceptor atrophy in dry AMD and STGD1.

Testosterone synthesis in testicular Leydig cells after long-term exposure to a static electric field (SEF)

China’s clean energy and resources are mainly located in the west and north while electric load center is concentrated in the middle and east. Thus, these resources and energy need to be converted into electrical energy in situ and transported to electric load center through ultra-high voltage direct current (UHVDC) transmissions. China has built 25,000 km UHVDC transmission lines of 800 kV and 1100 kV, near which the impact of electric field on health has attracted public attention. Previous studies showed that time-varying electromagnetic field exposure could disturb testosterone secretion. To study the effect of non-time-varying electric field caused by direct current transmission lines on testosterone synthesis, male ICR mice were continually (24 h/d) exposed to static electric field of 56.3 ± 1.4 kV/m. Results showed that on the 3rd day of exposure and on the 7th day after ceasing the exposure of 28 d, serum testosterone level and testicular oxidative stress indicators didn’t change significantly. On the 28th day of exposure, serum testosterone levels, testicular glutathione peroxidase (GSH-Px) activity, the mRNA and protein levels of testicular StAR, PBR, CYP11A1 decreased significantly, and testicular malondialdehyde (MDA) content increased significantly. Meanwhile, electron-dense edges and vacuolation appeared in lipid droplets of Leydig cells. The gap between inner mitochondrial membrane (IMM) and outer mitochondrial membrane (OMM) enlarged, which would cause the swelling of mitochondria, the rupture and deficiency of mitochondrial membranes. Analysis showed that testicular oxidative stress could induce the damage of mitochondrial structure in Leydig cells, which would decrease the rate of cholesterol transport from cytoplasm to mitochondria. Since cholesterol is the necessary precursor of testosterone synthesis, testosterone synthesis was inhibited. The decrease of the mRNA and protein expression levels of StAR and PBR in testes could diminish the cholesterol transported from OMM to IMM. The decrease of the mRNA and protein expression levels of CYP11A1 could reduce the pregnenolone required in testosterone synthesis and inhibit testosterone synthesis consequently.

Curcumin induces ferroptosis in non-small-cell lung cancer via activating autophagy.

BackgroundEmerging studies showed curcumin can inhibit glioblastoma and breast cancer cells via regulating ferroptosis. However, the role of ferroptosis in the inhibitory effect of curcumin on non‐small‐cell lung cancer (NSCLC) remains unclear.MethodsCell counting kit‐8 (CCK‐8) assay was used to measure the viability of A549 and H1299 cells under different conditions. Cell proliferation was examined by Ki67 immunofluorescence. The morphological changes of cells and tumor tissues were observed by optical microscope and hematoxylin and eosin (H&E) staining. Intracellular reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and iron contents were determined by corresponding assay kit. The related protein expression levels were detected by western blot and immunohistochemistry. Transmission electron microscope was used to observe ultrastructure changes of A549 and H1299 cells.ResultsCurcumin inhibited tumor growth and cell proliferation, but promoted cell death. Characteristic changes of ferroptosis were observed in curcumin group, including iron overload, GSH depletion and lipid peroxidation. Meanwhile, the protein level of ACSL4 was higher and the levels of SLC7A11 and GPX4 were lower in curcumin group than that in control group. Incubation of ferroptosis inhibitors ferrostatin‐1 (Fer‐1) or knockdown of iron‐responsive element‐binding protein 2 (IREB2) notably weakened curcumin‐induced anti‐tumor effect and ferroptosis in A549 and H1299 cells. Further investigation suggested that curcumin induced mitochondrial membrane rupture and mitochondrial cristae decrease, increased autolysosome, increased the level of Beclin1 and LC3, and decreased the level of P62. Curcumin‐induced autophagy and subsequent ferroptosis were both alleviated with autophagy inhibitor chloroquine (CQ) or siBeclin1.ConclusionCurcumin induced ferroptosis via activating autophagy in NSCLC, which enhanced the therapeutic effect of NSCLC.

A Full Set of In Vitro Assays in Chitosan/Tween 80 Microspheres Loaded with Magnetite Nanoparticles.

Microspheres have been proposed for different medical applications, such as the delivery of therapeutic proteins. The first step, before evaluating the functionality of a protein delivery system, is to evaluate their biological safety. In this work, we developed chitosan/Tween 80 microspheres loaded with magnetite nanoparticles and evaluated cell damage. The formation and physical–chemical properties of the microspheres were determined by FT-IR, Raman, thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), and SEM. Cell damage was evaluated by a full set of in vitro assays using a non-cancerous cell line, human erythrocytes, and human lymphocytes. At the same time, to know if these microspheres can load proteins over their surface, bovine serum albumin (BSA) immobilization was measured. Results showed 7 nm magnetite nanoparticles loaded into chitosan/Tween 80 microspheres with average sizes of 1.431 µm. At concentrations from 1 to 100 µg/mL, there was no evidence of changes in mitochondrial metabolism, cell morphology, membrane rupture, cell cycle, nor sister chromatid exchange formation. For each microgram of microspheres 1.8 µg of BSA was immobilized. The result provides the fundamental understanding of the in vitro biological behavior, and safety, of developed microspheres. Additionally, this set of assays can be helpful for researchers to evaluate different nano and microparticles.

Homocysteine induces mitochondrial dysfunction and oxidative stress in myocardial ischemia/reperfusion injury through stimulating ROS production and the ERK1/2 signaling pathway

Acute oxidative stress and mitochondrial dysfunction are crucial for acute myocardial ischemia-reperfusion (AMI/R) injury, which may induce cell or mitochondrial membrane rupture and myocardial infarction. Plasma homocysteine (Hcy) expression levels are positively associated with risk of cardiovascular disease, and ERK1/2 exert anti-apoptotic and cardioprotective effects on AMI/R injury. However, the precise molecular mechanism of action underlying the effects of Hcy and the ERK1/2 signaling pathway on mitochondrial dysfunction and oxidative stress in AMI/R injury remains unclear. In the present study, AMI/R injury models were established in an animal model treated with Hcy and in H9C2 cells that were treated with hypoxia-reoxygenation. Mitochondrial function and oxidative stress were evaluated. The results demonstrated that Hcy enhanced ERK1/2 protein expression levels and oxidative stress, induced cytochrome c translocation and mitochondria dysfunction, and caused cardiac dysfunction in rats with AMI/R injury. However, an ERK1/2 inhibitor effectively protected AMI/R injury rats from Hcy-induced cardiac dysfunction and oxidative stress. In conclusion, Hcy induced mitochondrial dysfunction and oxidative stress in AMI/R injury through stimulating ROS production and the ERK1/2 signaling pathway. An ERK1/2 inhibitor may be an effective new therapeutic method for treating Hcy-induced cardiac dysfunction in patients with AMI/R injury.

PM2.5 triggered apoptosis in lung epithelial cells through the mitochondrial apoptotic way mediated by a ROS-DRP1-mitochondrial fission axis

Epidemiological studies revealed a sharp increase in respiratory diseases attributed to PM2.5. However, the underlying mechanisms remain unclear. Evidence suggested mitochondrion as a sensitive target upon the stimulus of PM2.5, and the centrality in the pathological processes and clinical characterization of lung diseases. To investigate cell fate and related mechanisms caused by PM2.5, we exposed human lung epithelial cells (BEAS-2B) to PM2.5 (0-100 μg/mL). Consequently, PM2.5 components were found in cytoplasm, and morphological and functional alterations in mitochondria occurred, as evidenced by loss of cristae, vacuolization and even the outer mitochondrial membrane rupture, mitochondrial membrane potential collapse, enhanced reactive oxygen species (ROS)/mtROS level, calcium overload, suppressed cellular respiration and ATP production in PM2.5-treated cells. Further, disturbed dynamics toward fission was clearly observed in PM2.5-treated mitochondria, associated with DRP1 mitochondrial translocation and phosphorylation. Besides, PM2.5 induced mitochondria-mediated apoptosis. More importantly, mechanistic results revealed ROS- and DRP1-mediated mitochondrial fission in a reciprocal way, and DRP1 inhibitor (Mdivi-1) significantly alleviated the pro-apoptotic effect of PM2.5 through reversing the activated mitochondrial apoptotic pathway. In summary, our results firstly revealed PM2.5 induced apoptosis in lung epithelial cells through a ROS-DRP1-mitochodrial fission axis-mediated mitochondrial apoptotic pathway, ultimately contributing to the onset and development of pulmonary diseases.

Effects of propofol on LC3II and mTOR/p-mTOR expression during ischemia-reperfusion myocardium injury in rats with type 2 diabetes mellitus.

To investigate the effects of propofol on myocardial ischemia reperfusion in rats with type 2 diabetes, male adult rats were divided into five groups: Sham-operation (CC), ischemia-reperfusion (CI), low-dose propofol (LP), moderate-dose propofol (MP) and high-dose propofol (HP). The LP, MP and HP groups were administered with 6, 12 and 24 mg/kg/h propofol, respectively, prior to occlusion. Heart rate (HR), left ventricular systolic pressure (LVSP) and the rate (dp/dt max) of left ventricular pressure rise in early systole (±dp/dt max) were recorded. The role of autophagy was also studied by measuring the levels of superoxide dismutase (SOD), malondialdehyde (MDA), autophagy marker protein LC3II, mammalian target of rapamycin (mTOR)/phosphorylate (p)-mTOR and cardiac troponin T (cTnT). The myocardial morphological features were assessed using light and electron microscopy. The present results demonstrated that the HR, LVSP, +dp/dt and -dp/dt levels in the propofol groups (LP, MP and HP) were significantly increased (P<0.05) when compared with the CI group. The myocardial cells in the MP group showed mild edematous changes and partially dissolved mitochondrial cristae and membrane rupture. SOD, cTnT and MDA levels were significantly decreased (P<0.05), mTOR expression decreased significantly (P<0.05) and p-mTOR expression increased significantly in the MP group (P<0.05). The present study demonstrated the protective effects of propofol in T2DM rats exhibiting MIRI, with an optimal protective effect at an infusion rate of 12 mg/kg/h. Additionally, the results revealed that propofol led to significant reductions in LC3II and mTOR serum levels and the inhibition of autophagy in myocardial cells.

Vitexin attenuates myocardial ischemia/reperfusion injury in rats by regulating mitochondrial dysfunction induced by mitochondrial dynamics imbalance

Vitexin (VT) is a main bioactive flavonoid compound derived from the dried leaf of hawthorn (Crataegus pinnatifida), a widely used Chinese traditional folk medicine. Recent studies have shown that vitexin presents cardioprotective effects in vivo and in vitro. Mitochondrial dysfunction is a salient feature of myocardial ischemia/reperfusion (I/R) injury (MIRI), but the potential mechanism is still unclear. This study investigated the cardioprotective effect of vitexin against MIRI and its possible mechanism. Isolated SD rat hearts were subjected to MIRI in a Langendorff perfusion system, and H9c2 cells were subjected to hypoxia/reoxygenation (H/R) in vitro. Ex vivo experiments showed improved left ventricular function and reduced infarct size in the vitexin group. Transmission electron microscopy showed that I/R caused outer mitochondrial membrane rupture, cristae disappearance and vacuolation, while vitexin reduced mitochondrial damage and ultimately reduced cardiomyocyte apoptosis. In vitro, vitexin protected H9c2 cells from H/R-induced mitochondrial dysfunction, significantly reducing ROS levels; improving mitochondrial activity, mitochondrial membrane potential and ATP content; markedly increasing MFN2 expression and reducing the recruitment of Drp1 in mitochondria. These results suggest a new protective mechanism of vitexin for ischemic heart disease treatment.

Photostable Fluorescent Tracker for Imaging Mitochondria with Super Resolution.

The power factories in cells, mitochondria, play important roles in all physiological processes. It is reported that progressive mitochondrial swelling and outer mitochondrial membrane rupture could be induced by a wide variety of apoptotic and necrotic stimuli. Regrettably, although a variety of mitochondrial probes have been developed, most of them are based on the detection of active species in mitochondria. Probes that can monitor the status and distribution of mitochondria for a long time are still urgently needed. In this study, a fluorescent sensor with excellent properties, EtNBEn, is described. Outstanding performance allows it to be observed not only in cells but also in living Daphnia and zebrafish under confocal microscopy for a long time. Moreover, the swelling process of mitochondria under light stimulation is also visualized under super-resolution (SR) microscopy. All these results suggest that EtNBEn could be employed for tagging mitochondria in various physiological processes, which makes a great contribution to the cure of diseases.

Morphological Stages of Mitochondrial Vacuolar Degeneration in Phenylephrine-Stressed Cardiac Myocytes and in Animal Models and Human Heart Failure.

Background and objectives: Derangements in mitochondrial integrity and function constitute an important pathophysiological feature in the pathogenesis of heart failure (HF) and play an important role in myocardial remodeling and systolic dysfunction. In systolic HF, we and others have shown an imbalance in mitochondrial dynamics toward mitochondrial fission and fragmentation with evidence of mitophagy, mitochondrial vacuolar degeneration, and impairment in mitochondrial oxidative capacity. The morphological stages of mitochondrial vacuolar degeneration have not been defined. We sought to elucidate the progressive stages of mitochondrial vacuolar degeneration, which would serve as a measure to define, morphologically, the severity of mitochondrial damage. Materials and Methods: Transmission electron microscopy was used to study mitochondrial morphology and pathology in phenylephrine-stressed cardiac myocytes in vitro and in left ventricular myocardium from a rat model of pressure overload induced systolic dysfunction and from patients with systolic HF. Results: In phenylephrine-stressed cardiomyocytes for two hours, alterations in mitochondrial cristae morphology (Stage A) and loss and dissolution of mitochondrial cristae in one (Stage B) or multiple (early Stage B→C) mitochondrion area(s) were evident in the earliest stages of mitochondrial vacuolar degeneration. Mitochondrial swelling and progressive dissolution of mitochondrial cristae (advanced Stage B→C), followed by complete loss and dissolution of mitochondrial cristae and permeabilization and destruction of inner mitochondrial membrane (Stage C) then outer mitochondrial membrane rupture (Stage D) constituted advanced stages of mitochondrial vacuolar degeneration. Similar morphological changes in mitochondrial vacuolar degeneration were seen in vivo in animal models and in patients with systolic HF; where about 60–70% of the mitochondria are mainly observed in stages B→C and fewer in stages C and D. Conclusion: Mitochondrial vacuolar degeneration is a prominent mitochondrial morphological feature seen in HF. Defining the progressive stages of mitochondrial vacuolar degeneration would serve as a measure to assess morphologically the severity of mitochondrial damage.