Cadmium induces ferroptosis and apoptosis by modulating miR-34a-5p/Sirt1axis in PC12 cells

Cadmium (Cd) is a potent neurotoxic metal present in the environment and food. In this study, CdCl₂ (2 or 4 μM) induced cytotoxicity and neurotoxicity in PC12 cells, causing decreases in cell viability and NEP protein expression and increase in p-tau protein expression. For the first time, CdCl₂-initiated injury was found to result from the induction of not only apoptosis but also ferroptosis, as evidenced by the increased iron content, ROS production, and mitochondrial membrane potential along with changes in the expressions of iron death-related genes (FTH1, GPX4, ASCL4, PTGS2, and NOX1) and levels of caspase9, Bax, and Bcl-2 proteins. The molecular mechanisms leading to apoptosis and ferroptosis at least included the participation of the miR-34a-5p/Sirt1 axis, in which miR-34a-5p promoted CdCl₂-induced neurotoxicity through targeting Sirt1. Knocking out miR-34a-5p attenuated CdCl₂-induced damage of PC12 cells, cytotoxicity and neurotoxicity. This research provides the underlying molecular mechanisms of CdCl₂-induced damage and asserts the role of miRNAs as critical regulators.     

Kaempferol protects MC3T3-E1 cells through antioxidant effect and regulation of mitochondrial function

Kaempferol, a natural flavonoid present in fruits, vegetables, and teas, provides beneficial effects for human health. In this study, we investigated the protective effects of kaempferol on antimycin A (AMA)-induced toxicity in osteoblast-like MC3T3-E1 cells. Exposure of MC3T3-E1 cells to AMA caused significant cell viability loss, as well as mitochondrial membrane potential dissipation, complex IV inactivation, intracellular calcium ([Ca²⁺]_i) elevation, and reactive oxygen species (ROS) production. Pretreatment with kaempferol prior to AMA exposure significantly reduced AMA-induced cell damage by preventing mitochondrial membrane potential dissipation, complex IV inactivation, [Ca²⁺]_i elevation, and ROS production. Kaempferol also induced the activation of PI3K (phosphoinositide 3-kinase), Akt (protein kinase B), and CREB (cAMP-response element-binding protein) inhibited by AMA, which result demonstrates that kaempferol utilizes the PI3K/Akt/CREB pathway to augment metabolic activity inhibited by AMA. All these data indicate that kaempferol may reduce or prevent osteoblasts degeneration in osteoporosis or other degenerative disorders.     

Attenuation of Aβ25–35-induced parallel autophagic and apoptotic cell death by gypenoside XVII through the estrogen receptor-dependent activation of Nrf2/ARE pathways

Amyloid-beta (Aβ) has a pivotal function in the pathogenesis of Alzheimer's disease. To investigate Aβ neurotoxicity, we used an in vitro model that involves Aβ_25–35-induced cell death in the nerve growth factor-induced differentiation of PC12 cells. Aβ_25–35 (20 μM) treatment for 24 h caused apoptotic cell death, as evidenced by significant cell viability reduction, LDH release, phosphatidylserine externalization, mitochondrial membrane potential disruption, cytochrome c release, caspase-3 activation, PARP cleavage, and DNA fragmentation in PC12 cells. Aβ_25–35 treatment led to autophagic cell death, as evidenced by augmented GFP-LC3 puncta, conversion of LC3-I to LC3-II, and increased LC3-II/LC3-I ratio. Aβ_25–35 treatment induced oxidative stress, as evidenced by intracellular ROS accumulation and increased production of mitochondrial superoxide, malondialdehyde, protein carbonyl, and 8-OHdG. Phytoestrogens have been proved to be protective against Aβ-induced neurotoxicity and regarded as relatively safe targets for AD drug development. Gypenoside XVII (GP-17) is a novel phytoestrogen isolated from Gynostemma pentaphyllum or Panax notoginseng. Pretreatment with GP-17 (10 μM) for 12 h increased estrogen response element reporter activity, activated PI3K/Akt pathways, inhibited GSK-3β, induced Nrf2 nuclear translocation, augmented antioxidant responsive element enhancer activity, upregulated heme oxygenase 1 (HO-1) expression and activity, and provided protective effects against Aβ_25–35-induced neurotoxicity, including oxidative stress, apoptosis, and autophagic cell death. In conclusion, GP-17 conferred protection against Aβ_25–35-induced neurotoxicity through estrogen receptor-dependent activation of PI3K/Akt pathways, inactivation of GSK-3β and activation of Nrf2/ARE/HO-1 pathways. This finding might provide novel insights into understanding the mechanism for neuroprotective effects of phytoestrogens or gypenosides.     

EGFR-dependent ERK activation triggers hydrogen peroxide-induced apoptosis in OK renal epithelial cells

Oxidative stress induces activation of extracellular signal-regulated kinase (ERK), a member of the mitogen-activated protein kinase families. However, it is unclear in renal epithelial cells whether the ERK activation is involved in cell survival or cell death in H₂O₂-treated cells. The present study was undertaken to determine the role of the ERK activation in H₂O₂-induced apoptosis of renal epithelial cells using opossum kidney (OK) cells, an established proximal tubular epithelial cell line. H₂O₂ resulted in a time- and dose-dependent apoptosis of OK cells. H₂O₂ treatment caused marked sustained activation of ERK. The ERK activation was prevented by PD98059 and U0126, inhibitors of ERK1/2 upstream kinase MEK1/2. Apoptosis caused by H₂O₂ was prevented by U0126. Transient transfection with constitutive active MEK1 increased the H₂O₂-induced apoptosis, whereas transfection with dominant-negative mutants of MEK1 decreased the apoptosis. H₂O₂ produced hyperpolarization of mitochondrial membrane potential and activation of caspases-3. H₂O₂-induced ERK activation was inhibited by the Src family selective inhibitor PP2 and the epidermal growth factor receptor inhibitor AG1478. The presence of AG1478, but not PP2, prevented H₂O₂-induced cell death. Taken together, our findings suggest that the ERK activation mediated by epidermal growth factor receptor plays an active role in inducing H₂O₂-induced apoptosis of OK cells and functions upstream of mitochondria-dependent pathway to initiate the apoptotic signal.     

Icaritin inhibits oxidative stress in murine astrocytes by binding to Orai1 to block store-operated calcium channel

Previous study has shown that icaritin (ICT) has meaningful protective effect on cerebral ischemic stroke, and this study aimed to investigate its mechanism from the aspect of protecting astrocytes from oxidative stress. Murine primary astrocytes were pretreated by ICT and exposed to H₂O₂ to induce oxidative stress. The results indicated that ICT inhibited H₂O₂-induced astrocytes apoptosis, decreased Bax and cleaved caspase-3, and increased Bcl-2. In addition, ICT inhibited H₂O₂-induced oxidative stress, increased mitochondrial membrane potential (ΔΨ_m), and maintained mitochondrial morphology. ICT decreased the synthesis of malondialdehyde and increased the activity of glutathione peroxidase, catalase, and superoxide dismutase. Moreover, ICT suppressed the transient and resting intracellular Ca²⁺ overload. Further investigation revealed that ICT could target the combination with Orai1 to block store-operated calcium channel induced by H₂O₂. However, ICT did not enhance the protective effect of RO2959, a selective blocker of Orai1. These results indicate that ICT can play a neuroprotective role against oxidative stress injury by binding to Orai1 to block SOCC.     

15-Deoxy-Δ-prostaglandin J2 induces mitochondrial-dependent apoptosis through inhibition of PKA/NF-κB in renal proximal epithelial cells

We have previously reported the cyclopentenone prostaglandin 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) induces renal proximal epithelial cell death through NF-κB inhibition. However, the upstream and down-stream signaling pathways that NF-κB inhibition mediates 15d-PGJ₂-induced apoptosis remain to be defined. In the present study, we determined whether NF-κB inhibition induces cell death through the mitochondrial apoptotic pathway and whether protein kinase A (PKA) functions upstream of NF-κB inhibition by 15d-PGJ₂. The role of NF-κB inhibition in this apoptotic pathway was evaluated using NF-κB p65 transfected cells. 15d-PGJ₂ induced cell death by a PPARγ-independent mechanism and the cell death was prevented by NF-κB p65 transfection. 15d-PGJ₂ treatment caused disruption of mitochondrial membrane potential, cytochrome c release, and caspase-3 activation, suggesting that 15d-PGJ₂ induces cell death through a mitochondria-dependent apoptotic mechanism. These changes by 15d-PGJ₂ were attenuated by NF-κB p65 transfection. 15d-PGJ₂ treatment resulted in an increase in Bax expression, which were blocked by NF-κB p65 transfection. 15d-PGJ₂ treatment caused PKA inhibition and 15d-PGJ₂-induced cell death was enhanced by the PKA specific inhibitor H89. Inhibition of NF-κB by 15d-PGJ₂ was prevented by addition of forskolin, a PKA activator. Taken together, these results suggest that PKA-dependent NF-κB inhibition stimulates 15d-PGJ₂-mediated mitochondrial apoptotic pathway through alterations in expression of the NF-κB target genes Bax.     

Epigallocatechin-3-gallate protects rat brain mitochondria against cadmium-induced damage

Many health claims have been made about the medicinal benefits of drinking green tea, including neuroprotection. This study mainly focuses on Epigallocatechin 3-gallate (EGCG), a potent antioxidant, which is abundantly found in green tea. Cadmium [Cd²⁺] is a toxic pollutant that leads to neurotoxicity in both animals and humans. Although the entrance of Cd²⁺ in the adult central nervous system is limited, developmental neurotoxicity has been evidenced as result of the blood-brain barrier (BBB) immaturity. Moreover, high Cd²⁺ levels are known to impair BBB function. Furthermore, the molecular mechanisms related to its neurotoxic properties remain unknown. This study evaluates the potential protective effect of the major green tea polyphenol, EGCG, against Cd²⁺-induced mitotoxicity under in vitro conditions, using mitochondrial-enriched fractions from rat brain. Co-incubation of EGCG with Cd²⁺ prevented the Cd²⁺-induced mitochondrial dysfunction (capacity to reduce MTT to formazan). In addition, EGCG completely prevented mitochondrial lipid peroxidation induced by Cd²⁺ but did not affect non protein thiols levels. Spectroscopic studies have shown EGCG able to form a chemical complex with Cd²⁺, in an equimolar ratio. In this study we demonstrate EGCG effectiveness in protecting against Cd²⁺-induced mitochondrial dysfunction and lipid peroxidation probably due to its antioxidant and chelating effects.     

Evaluation of Cadmium-Induced Nephrotoxicity Using Urinary Metabolomic Profiles in Sprague-Dawley Male Rats

The aim of this study was to investigate urinary metabolomic profiles associated with cadmium (Cd)-induced nephrotoxicity and their potential mechanisms. Metabolomic profiles were measured by high-resolution ¹H-nuclear magnetic resonance (NMR) spectroscopy in the urine of rats after oral exposure to CdCl₂ (1, 5, or 25 mg/kg) for 6 wk. The spectral data were further analyzed by a multivariate analysis to identify specific urinary metabolites. Urinary excretion levels of protein biomarkers were also measured and CdCl₂ accumulated dose-dependently in the kidney. High-dose (25 mg/kg) CdCl₂ exposure significantly increased serum blood urea nitrogen (BUN), but serum creatinine (sCr) levels were unchanged. High-dose CdCl₂ (25 mg/kg) exposure also significantly elevated protein-based urinary biomarkers including osteopontin, monocyte chemoattractant protein-1 (MCP-1), kidney injury molecules-1 (Kim-1), and selenium-binding protein 1 (SBP1) in rat urine. Under these conditions, six urinary metabolites (citrate, serine, 3-hydroxyisovalerate, 4-hydroxyphenyllactate, dimethylamine, and betaine) were involved in mitochondrial energy metabolism. In addition, a few number of amino acids such as glycine, glutamate, tyrosine, proline, or phenylalanine and carbohydrate (glucose) were altered in urine after CdCl₂ exposure. In particular, the metabolites involved in the glutathione biosynthesis pathway, including cysteine, serine, methionine, and glutamate, were markedly decreased compared to the control. Thus, these metabolites are potential biomarkers for detection of Cd-induced nephrotoxicity. Our results further indicate that redox metabolomics pathways may be associated with Cd-mediated chronic kidney injury. These findings provide a biochemical pathway for better understanding of cellular mechanism underlying Cd-induced renal injury in humans.     

Honokiol inhibits H(2)O(2)-induced apoptosis in human lens epithelial cells via inhibition of the mitogen-activated protein kinase and Akt pathways

Oxidative stress-induced apoptosis in lens epithelial cells plays an important role in cataract formation, and its prevention may be of therapeutic interest. This study was performed to investigate the protective effect and mechanisms of honokiol on H₂O₂-induced apoptosis in human lens epithelial (HLE) cells. HLE cells (SRA01-04) were pretreated with honokiol at concentrations of 5 μM, 10 μM and 20 μM before 50 μM H₂O₂ treatment. The results demonstrated that pretreatment of honokiol inhibited the activation of caspase-3 and caspase-9 and downregulated the expression of Bcl-2. Mechanistically, honokiol suppressed H₂O₂-induced phosphorylation of ERK1/2, p38 mitogen-activated protein kinase (MAPK), JNK and Akt. Honokiol also inhibited H₂O₂-induced nuclear factor-κB (NF-κB)/p65 phosphorylation and translocation in HLE cells. These results demonstrate that honokiol suppresses H₂O₂-induced HLE cell apoptosis via interference with the MAPKs, Akt and NF-κB signaling, suggesting that honokiol might have a potential effect against cataract formation.     

Prevention of cadmium-induced toxicity in liver-derived cells by the combination preparation Hepeel(®)

Cadmium is a heavy metal of considerable environmental concern that causes liver damage. This study examined the possible prevention of cadmium toxicity in human HepG2 cells and primary rat hepatocytes by Hepeel^®, a combined preparation of tinctures from seven different plants. Hepeel^® prevented cadmium chloride (CdCl₂)-induced cell death in both HepG2 cells and hepatocytes, and also reduced the loss of glutathione, lipid peroxidation, nuclear fragmentation, caspase activation and release of mitochondrial cytochrome C. To compare their relative efficacy, the seven constituent plant tinctures of Hepeel^® were also separately tested. The tinctures China and Nux moschata, which exert solely anti-oxidative effects, failed to reduce cytotoxicity, and only protected against loss of glutathione and lipid peroxidation. In contrast, the tinctures Carduus marianus and Chelidonium, demonstrated anti-apoptotic effects, and protected HepG2 cells and primary hepatocytes against CdCl₂-induced cell death. These results demonstrate how the effectiveness of Hepeel^® is determined by the synergistic features of its constituent tinctures. Furthermore, we conclude that cadmium toxicity in the liver is mainly due to stimulation of the intrinsic apoptotic pathway, but may be intensified by increased oxidative stress.     

Hydrogen sulfide alleviates apoptosis and autophagy induced by beryllium sulfate in 16HBE cells

Beryllium and its compounds are systemic toxicants that are widely applied in many industries. Hydrogen sulfide has been found to protect cells. The present study aimed to determine the protective mechanisms involved in hydrogen sulfide treatment of 16HBE cells following beryllium sulfate-induced injury. 16HBE cells were treated with beryllium sulfate doses ranging between 0 and 300 μM BeSO₄. Additionally, 16HBE cells were subjected to pretreatment with either a 300 μM dose of sodium hydrosulfide (a hydrogen sulfide donor) or 10 mM DL-propargylglycine (a cystathionine-γ-lyase inhibitor) for 6 hr before then being treated with 150 μM beryllium sulfate for 48 hr. This study illustrates that beryllium sulfate induces a reduction in cell viability, increases lactate dehydrogenase (LDH) release, and increases cellular apoptosis and autophagy in 16HBE cells. Interestingly, pretreating 16HBE cells with sodium hydrosulfide significantly reduced the beryllium sulfate-induced apoptosis and autophagy. Moreover, it increased the mitochondrial membrane potential and alleviated the G2/M-phase cell cycle arrest. However, pretreatment with 10 mM DL-propargylglycine promoted the opposite effects. PI3K/Akt/mTOR and Nrf2/ARE signaling pathways are also activated following pretreatment with sodium hydrosulfide. These results indicate the protection provided by hydrogen sulfide in 16HBE cells against beryllium sulfate-induced injury is associated with the inhibition of apoptosis and autophagy through the activation of the PI3K/Akt/mTOR and Nrf2/ARE signaling pathways. Therefore, hydrogen sulfide has the potential to be a promising candidate in the treatment against beryllium disease.     

Increased apoptotic efficacy of lonidamine plus arsenic trioxide combination in human leukemia cells. Reactive oxygen species generation and defensive protein kinase (MEK/ERK, Akt/mTOR) modulation

Lonidamine is a safe, clinically useful anti-tumor drug, but its efficacy is generally low when used in monotherapy. We here demonstrate that lonidamine efficaciously cooperates with the anti-leukemic agent arsenic trioxide (ATO, Trisenox™) to induce apoptosis in HL-60 and other human leukemia cell lines, with low toxicity in non-tumor peripheral blood lymphocytes. Apoptosis induction by lonidamine/ATO involves mitochondrial dysfunction, as indicated by early mitochondrial permeability transition pore opening and late mitochondrial transmembrane potential dissipation, as well as activation of the intrinsic apoptotic pathway, as indicated by Bcl-X_L and Mcl-1 down-regulation, Bax translocation to mitochondria, cytochrome c and Omi/HtrA2 release to the cytosol, XIAP down-regulation, and caspase-9 and -3 cleavage/activation, with secondary (Bcl-2-inhibitable) activation of the caspase-8/Bid axis. Lonidamine stimulates reactive oxygen species production, and lonidamine/ATO toxicity is attenuated by antioxidants. Lonidamine/ATO stimulates JNK phosphorylation/activation, and apoptosis is attenuated by the JNK inhibitor SP600125. In addition, lonidamine elicits ERK and Akt/mTOR pathway activation, as indicated by increased ERK, Akt, p70S6K and rpS6 phosphorylation, and these effects are reduced by co-treatment with ATO. Importantly, co-treatment with MEK/ERK inhibitor (U0126) and PI3K/Akt (LY294002) or mTOR (rapamycin) inhibitors, instead of ATO, also potentiates lonidamine-provoked apoptosis. These results indicate that: (i) lonidamine efficacy is restrained by drug-provoked activation of MEK/ERK and Akt/mTOR defensive pathways, which therefore represent potential therapeutic targets. (ii) Co-treatment with ATO efficaciously potentiates lonidamine toxicity via defensive pathway inhibition and JNK activation. And (iii) conversely, the pro-oxidant action of lonidamine potentiates the apoptotic efficacy of ATO as an anti-leukemic agent.     

Oxyresveratrol protects human lens epithelial cells against hydrogen peroxide-induced oxidative stress and apoptosis by activation of Akt/HO-1 pathway

Oxidative stress induced by hydrogen peroxide (H₂O₂) triggers human lens epithelial cell (HLEC) apoptosis and initiates cataract formation. Oxyresveratrol (Oxy) was reported to possess antioxidant and free radical scavenging activities. Herein, we investigated the effects of Oxy on H₂O₂-induced oxidative stress and apoptosis in HLECs and the associated mechanisms. Cell viability was detected by MTT assay. The oxidative damage was assessed by measuring the activities of superoxide dismutases-1 (SOD-1), catalase (CAT), glutathione reductase (GSH), and malondialdehyde (MDA). Apoptosis was analyzed by flow cytometry analysis. The changed expressions of heme oxygenase-1 (HO-1) and protein kinase B (Akt) pathways were evaluated by qRT-PCR and western blot. We found that exposure to H₂O₂ dose-dependently reduced cell viability, and induced oxidative stress and apoptosis in HLECs, which were reversed by pretreatment with Oxy. Oxy increased p-Akt and HO-1 expressions in H₂O₂-stimulated HLECs. Akt and HO-1 expressions form a regulatory axis and Oxy activated the Akt/HO-1 pathway in H₂O₂-stimulated HLECs. Inhibition of the Akt/HO-1 pathway by LY294002 or ZnPP attenuated the effects of Oxy on oxidative stress and apoptosis in H₂O₂-stimulated HLECs. In conclusion, Oxy protected H₂O₂-induced oxidative stress and apoptosis through activating the Akt/HO-1 pathway, suggesting the protective effect of Oxy against H₂O₂-induced cataract.     

Vanillin attenuates CdCl2-induced cytotoxicity in isolated human erythrocytes

Cadmium is a toxic heavy metal with no physiological role in the human body. Cadmium has high mobility due to its widespread industrial use, with no safe and effective therapeutic management. Cadmium toxicity manifests by increasing oxidative stress in target cells. We have explored the potential role of vanillin, a plant phenolic aldehyde and antioxidant, in mitigating cadmium chloride (CdCl₂) induced hemotoxicity using isolated human erythrocytes. CdCl₂ was added to erythrocytes, in the absence and presence of vanillin. Incubation of erythrocytes with CdCl₂ alone inhibited methemoglobin reductase and enhanced methemoglobin level. Heme degradation and release of free iron (Fe²⁺), along with protein and membrane lipid oxidation, were also increased. A CdCl₂-induced enhancement in reactive oxygen and nitrogen species was also seen, lowering the overall antioxidant power of cells. However, pre-incubation of erythrocytes with vanillin resulted in significant decreased generation of reactive species and prevented heme degradation and heme oxidation. Vanillin augmented the erythrocyte antioxidant capacity and reinstated the activities of major antioxidant, plasma membrane-bound and glucose metabolism enzymes. Scanning electron microscopy showed that CdCl₂ treatment led to the formation of echinocytes which was prevented by vanillin. In all cases, no harmful effects of vanillin alone were seen. Thus, vanillin alleviates the toxicity of cadmium and can be potentially employed as a chemoprotectant against the damaging effects of this heavy metal.     

Leukamenin F suppresses liver fibrogenesis by inhibiting both hepatic stellate cell proliferation and extracellular matrix production

Aim:

To investigate the inhibitory effect of the natural product Leukamenin F on liver fibrosis and explore its potential underlying mechanisms.

Methods:

Carbon tetrachloride (CCl₄)-treated mouse model in vivo and in hepatic stellate cells (HSC) in vitro were used. The effect on CCl₄-induced liver fibrosis was studied using histochemical and biochemical analysis, while the inhibition on HSC was assessed using cell proliferation/apoptosis assay and collagen I production using real-time PCR. The inhibitory effects of Leukamenin F on Akt/mTOR/p70S6K and TGFβ/Smad pathways was studied using Western blot and cell image analysis.

Results:

Leukamenin F (0.1–1 mg/kg, ip, q.d.×28) significantly reduced α-SMA and collagen specific Sirius red staining areas in CCl₄ -treated mouse livers. This compound at 1–2 μmol/L dose-dependently inhibited α-SMA expression, cell proliferation and type I procollagen mRNA expression in activated HSC. Furthermore it inhibited the Akt/mTOR/p70S6K pathway and suppressed TGFβ -induced Smad2/Smad3 phosphorylation and nuclear translocation in HSC.

Conclusion:

Our results demonstrated that Leukamenin F could attenuate CCl₄-induced liver fibrogenesis in mice as an efficient inhibitor against both HSC proliferation and ECM production. This natural product provides a valuable structural hint for the development of anti-liver fibrosis reagents.     

Ghrelin protects H9c2 cells from hydrogen peroxide-induced apoptosis through NF-κB and mitochondria-mediated signaling

Oxidative stress is a major mechanism underlying the pathogenesis of cardiovascular disease. Herein we investigate the protective effects of ghrelin in H₂O₂-induced apoptosis of H9c2 cells, as well as the possible molecular mechanisms involved. To study apoptosis, the cells were assessed by morphologic examination, MTS assay, Annexin V–propidium iodide dual staining and TUNEL analysis. Intracellular reactive oxygen species (ROS) production and mitochondrial membrane potential were also measured. To investigate the underlying molecular mechanisms, the expression of Bcl-2, Bax, active caspase-9 and NF-κB were assessed by Western blotting, and caspase-3 activity was determined by a colorimetric activity assay kit. After stimulation with H₂O₂ for 18 h, H9c2 cells viability decreased significantly; a large fraction of cells underwent apoptosis. We observed a dose-dependent rescue of H9c2 cells from H₂O₂-induced apoptosis in the presence of different ghrelin concentrations. Preincubation with ghrelin also restored the ROS and mitochondrial membrane potential levels that had been altered by H₂O₂ treatment. Moreover, ghrelin decreased H₂O₂-induced Bax production and caspase-9 activation, and increased Bcl-2 levels. NF-κB phosphorylation was also significantly inhibited by ghrelin in H₂O₂-treated cells. Caspase-3 activation was suppressed by ghrelin in H₂O₂-treated H9c2 cells in a dose-dependent manner. In summary, ghrelin protects H9c2 cells from oxidative stress-induced apoptosis through downregulation of Bax expression, caspase-9 activation and NF-κB phosphorylation, and upregulation of Bcl-2 expression. Caspase-3 activation was also reduced in a dose-dependent manner. These data suggest that ghrelin might protect against cardiovascular disease by protecting the mitochondria.     

The Akt inhibitor,triciribine, ameliorates chronic hypoxia-induced vascular pruning and TGFβ-induced pulmonary fibrosis

Background and Purpose

Interstitial lung disease accounts for a group of chronic and progressive disorders associated with severe pulmonary vascular remodelling, peripheral vascular rarefaction and fibrosis, thus limiting lung function. We have previously shown that Akt is necessary for myofibroblast differentiation, a critical event in organ fibrosis. However, the contributory role of the Akt-mTOR pathway in interstitial lung disease and the therapeutic benefits of targeting Akt and mTOR remain unclear.

Experimental Approach

We investigated the role of the Akt-mTOR pathway and its downstream molecular mechanisms in chronic hypoxia- and TGFβ-induced pulmonary vascular pruning and fibrosis in mice. We also determined the therapeutic benefits of the Akt inhibitor triciribine and the mTOR inhibitor rapamycin for the treatment of pulmonary fibrosis in mice.

Key Results

Akt1^−/− mice were protected from chronic hypoxia-induced peripheral vascular pruning. In contrast, hyperactivation of Akt1 induced focal fibrosis similar to TGFβ-induced fibrosis. Pharmacological inhibition of Akt, but not the Akt substrate mTOR, inhibited hypoxia- and TGFβ-induced pulmonary vascular rarefaction and fibrosis. Mechanistically, we found that Akt1 modulates pulmonary remodelling via regulation of thrombospondin1 (TSP1) expression. Hypoxic Akt1^−/− mice lungs expressed less TSP1. Moreover, TSP1^−/− mice were resistant to adMyrAkt1-induced pulmonary fibrosis.

Conclusions and Implications

Our study identified Akt1 as a novel target for the treatment of interstitial lung disease and provides preclinical data on the potential benefits of the Akt inhibitor triciribine for the treatment of interstitial lung disease.     

Senkyunolide H protects against MPP+-induced apoptosis via the ROS-mediated mitogen-activated protein kinase pathway in PC12 cells

Senkyunolide H (SNH) is a phthalide isolated from the rhizome of Ligusticum chuanxiong Hort. that has been reported to have several pharmacological activities, including anti-atherosclerotic, antiproliferative, and cytoprotective effects. In this study, we investigated the neuroprotective effects and potential mechanisms of SNH against 1-methyl-4-phenylpyridinium (MPP⁺)-induced oxidative stress. We demonstrated that SNH pretreatment significantly attenuated MPP⁺-induced neurotoxicity and apoptosis in PC12 cells. In addition, SNH attenuated the effect of MPP⁺ on the expression of the pro-apoptotic factors Bax and caspase-3. Meanwhile, SNH prevented oxidative stress by reducing reactive oxygen species generation, mitochondrial membrane potential loss, cytochrome C release, and malondialdehyde levels while increasing antioxidant enzyme activity (e.g., superoxide dismutase, catalase, and glutathione peroxidase). In addition, SNH inhibited nuclear accumulation of nuclear factor-κB and c-Jun N-terminal kinase and phosphorylation p38 mitogen-activated protein kinases (MAPKs). Overall, this investigation provides novel evidence that SNH exerts neuroprotective effects via the ROS-mediated MAPK pathway and represents a potential preventive or therapeutic agent for neuronal disorders.