bims-aporos Biomed news
on Apoptosis and reactive oxygen species
Issue of 2018‒07‒29
nine papers selected by
Gavin McStay
Staffordshire University

  1. Biochim Biophys Acta. 2018 Jul 19. pii: S0005-2728(18)30197-X. [Epub ahead of print]
    Kamei Y, Koushi M, Aoyama Y, Asakai R.
      We investigated the properties of the permeability transition pore (PTP) in Saccharomyces cerevisiae in agar-embedded mitochondria (AEM) and agar-embedded cells (AEC) and its role in yeast death. In AEM, ethanol-induced pore opening, as indicated by the release of calcein and mitochondrial membrane depolarization, can be inhibited by CsA, by Cpr3 deficiency, and by the antioxidant glutathione. Notably, the pore opening is inhibited, when mitochondria are preloaded by EGTA or Fluo3 to chelate matrix Ca2+, or are pretreated with 4-Br A23187 to extract matrix Ca2+, prior to agar-embedding, or when pore opening is induced in the presence of EGTA; opened pores are re-closed by sequential treatment with CsA, 4-Br A23187 plus EGTA and NADH, indicating endogenous matrix Ca2+ involvement. CsA also inhibits the pore opening with low conductance triggered by exogenous Ca2+ transport with ETH129. In AEC, the treatment of tert-butylhydroperoxide, a pro-oxidant that triggers transient pore opening in high conductance in AEM, induces yeast death, which is also dependent on CsA and Cpr3. Furthermore, AEMs from mutants lacking three ADP/ATP carrier (AAC) isoforms and with defective ATP synthase dimerization exhibit high and low conductance pore openings with CsA sensitivity, respectively. Collectively, these data show that the yeast PTP is regulated by Cpr3, endogenous matrix Ca2+, and reactive oxygen species, and that it is involved in yeast death; furthermore, ATP synthase dimers play a key role in CsA-sensitive pore formation, while AACs are dispensable.
    Keywords:  Cpr3; Cyclosporin A; Endogenous matrix Ca(2+); Mitochondrial permeability transition pore; Reactive oxygen species; Saccharomyces cerevisiae
  2. Life Sci. 2018 Jul 18. pii: S0024-3205(18)30412-0. [Epub ahead of print]
    Rasheduzzaman M, Jeong JK, Park SY.
      AIMS: TRAIL is a promising anticancer agent that has the potential to sensitize a wide variety of cancer or transformed cells by inducing apoptosis. However, resistance to TRAIL is a growing concern. Current manuscript aimed to employing combination treatment to investigate resveratrol induced TRAIL sensitization in NSCLC.METHOD: A549 and HCC-15 cells were used in experimental design. Cell viability was determined by morphological image, crystal violet staining and MTT assay. Apoptosis was evaluated by LDH assay, Annexin V and DAPI staining. Autophagy and apoptosis indicator protein were examined by western blotting. TEM and puncta assay were carried out to evaluate the autophagy. MTP and ROS activity were evaluated by JC-1 and H2DCFDA staining.
    FINDINGS: Resveratrol is a polyphenolic compound capable of activation of tumor suppressor p53 and its pro-apoptotic modulator PUMA. Herein, we showed the p53-independent apoptosis by decrease the expression of phosphorylated Akt-mediated suppression of NF-κB that is also substantiated with the downregulation of anti-apoptotic factors Bcl-2 and Bcl-xl in NSCLC, resulting in an attenuation of TRAIL resistance in combined treatment. Furthermore, apoptosis was induced in TRAIL-resistant lung cancer cells with a co-treatment of resveratrol and TRAIL assessed by the loss of MMP, ROS generations which resulting the translocation of cytochrome c from the mitochondria into the cytosol due to mitochondrial dysfunction. Moreover, autophagy flux was not affected by resveratrol-induced TRAIL-mediated apoptosis in NSCLC.
    SIGNIFICANCE: Overall, targeting the NF-κB (p65) pathway via resveratrol attenuates TRAIL resistance and induces TRAIL-mediated apoptosis which could be the effective TRAIL-based cancer therapy regimen.
    Keywords:  Akt/NF-κB; Apoptosis; Cytochrome c; Lung cancer cells; Resveratrol; TRAIL
  3. Biochim Biophys Acta. 2018 Jul 18. pii: S0304-4165(18)30206-X. [Epub ahead of print]
    Cheng R, Takeda K, Naguro I, Hatta T, Iemura SI, Natsume T, Ichijo H, Hattori K.
      Apoptosis signal-regulating kinase 1 (ASK1) is a key player in the homeostatic response of many organisms. Of the many functions of ASK1, it is most well-known for its ability to induce canonical caspase 3-dependent apoptosis through the MAPK pathways in response to reactive oxygen species (ROS). As ASK1 is a regulator of apoptosis, its proper regulation is critical for the well-being of an organism. To date, several E3 ubiquitin ligases have been identified that are capable of degrading ASK1, signifying the importance of maintaining ASK1 expression levels during stress responses. ASK1 protein regulation under unstimulated conditions, however, is still largely unknown. Using tandem mass spectrometry, we have identified beta-transducin repeat containing protein (β-TrCP), an E3 ubiquitin ligase, as a novel interacting partner of ASK1 that is capable of ubiquitinating and subsequently degrading ASK1 through the ubiquitin-proteasome system (UPS). This interaction requires the seven WD domains of β-TrCP and the C-terminus of ASK1. By silencing the β-TrCP genes, we observed a significant increase in caspase 3 activity in response to oxidative stress, which could subsequently be suppressed by silencing ASK1. These findings suggest that β-TrCP is capable of suppressing oxidative stress-induced caspase 3-dependent apoptosis through suppression of ASK1, assisting in the organism's ability to maintain homeostasis in an unstable environment.
    Keywords:  ASK1; Apoptosis; E3 ubiquitin ligase; Oxidative stress; Ubiquitin-proteasome system; β-TrCP
  4. Toxicology. 2018 Jul 18. pii: S0300-483X(18)30157-4. [Epub ahead of print]
    Paech F, Abegg VF, Duthaler U, Terracciano L, Bouitbir J, Krähenbühl S.
      Reports concerning hepatic mitochondrial toxicity of sunitinib are conflicting. We therefore decided to conduct a toxicological study in mice. After having determined the highest dose that did not affect nutrient ingestion and body weight, we treated mice orally with sunitinib (7.5 mg/kg/day) for 2 weeks. At the end of treatment, peak sunitinib plasma concentrations were comparable to those achieved in humans and liver concentrations were approximately 25-fold higher than in plasma. Sunitinib did not affect body weight, but increased plasma ALT activity 6-fold. The activity of enzyme complexes of the electron transport chain (ETC) was decreased numerically in freshly isolated and complex III activity significantly in previously frozen liver mitochondria. In previously frozen mitochondria, sunitinib decreased NADH oxidase activity concentration-dependently in both treatment groups. The hepatic mitochondrial reactive oxygen species (ROS) content and superoxide dismutase 2 expression were increased in sunitinib-treated mice. Protein and mRNA expression of several subunits of mitochondrial enzyme complexes were decreased in mitochondria from sunitinib-treated mice. Protein expression of PGC-1α, citrate synthase activity and mtDNA copy number were all decreased in livers of sunitinib-treated mice, indicating impaired mitochondrial proliferation. Caspase 3 activation and TUNEL-positive hepatocytes were increased in livers of sunitinib-treated mice, indicating hepatocyte apoptosis. In conclusion, sunitinib caused concentration-dependent toxicity in isolated mitochondria at concentrations reached in livers in vivo and inhibited hepatic mitochondrial proliferation. Daily mitochondrial insults and impaired mitochondrial proliferation most likely explain hepatocellular injury observed in mice treated with sunitinib.
    Keywords:  PGC-1α; Sunitinib; apoptosis; hepatotoxicity; mitochondrial toxicity; reactive oxygen species (ROS)
  5. Cell Physiol Biochem. 2018 Jul 20. 48(2): 785-800
    Zhao Y, Zhang E, Lv N, Ma L, Yao S, Yan M, Zi F, Deng G, Liu X, He J, Wu W, Cai Z, Yu R.
      BACKGROUND/AIMS: Patients with multiple myeloma (MM) invariably relapse with chemotherapy-resistant disease, underscoring the need for new therapeutic options that bypass these resistance mechanisms. Metformin is a widely prescribed antidiabetic drug with direct antitumor activity against various tumor cell lines. FTY720, also known as fingolimod, is an immune-modulating agent approved by the FDA as oral medication to treat the relapsing form of multiple sclerosis (MS). In recent years, FTY720 has attracted attention due to its anti-tumor activity. To explore an optimized combinational therapy, interactions between metformin and FTY720 were examined in MM cells.METHODS: MTT assays were employed to assess the viability of MM cells. An apoptotic nucleosome assay was employed to measure apoptosis. Loss of mitochondrial membrane potential (MMP, ΔΨm) and cellular levels of ROS were measured by flow cytometry. qRT-PCR was used to analyze the expression of mRNAs. Western blotting assays were applied to measure the levels of proteins involved in different signaling pathways.
    RESULTS: Coadministration of metformin and FTY720 synergistically inhibited the proliferation of MM cells. Increased levels of apoptosis, activation of caspase-3 and cleavage of PARP were detected after cotreatment with metformin and FTY720. These events were associated with modulation of Bcl-2 proteins, loss of MMP, ER stress induction, and inhibition of the PI3K/AKT/mTOR signaling pathway. The metformin/FTY720 regimen markedly induced ROS generation; moreover, apoptosis, ER stress and inhibition of PI3K/AKT/ mTOR were attenuated by the ROS scavenger NAC.
    CONCLUSIONS: Exposure to metformin in combination with FTY720 potently induces apoptosis in MM cells in a ROS-dependent manner, suggesting that a strategy combining these agents warrants further investigation in MM.
    Keywords:  Apoptosis; ER stress; FTY720; Metformin; Mitochondrial membrane potential; Multiple myeloma; ROS
  6. Neurotoxicology. 2018 Jul 18. pii: S0161-813X(18)30136-0. [Epub ahead of print]68 73-80
    Song H, Huang LP, Li Y, Liu C, Wang S, Meng W, Wei S, Liu XP, Gong Y, Yao LH.
      In Alzheimer's disease (AD), β-amyloid (Aβ) protein toxicity increases the formation of reactive oxygen species (ROS) and intracellular calcium levels, resulting in neuronal dysfunction, neurodegenerative disorders, and cell death. Cordycepin is a derivative of the nucleoside adenosine; also, it is speculated to exert neuroprotective effects against Aβ-induced oxidative toxicity in hippocampal neurons. In the present study, the fluorescence detection method and whole-cell patch-clamp recordings were used to study the neuroprotective effects against Aβ-induced toxicity in the primary hippocampal cultured neurons. The results revealed that Aβ25-35 toxicity causes increased cellular ROS production and abnormal calcium homeostasis in hippocampal neurons. Moreover, Aβ25-35-induced cytotoxicity led to a series of downstream events, including the activation of acetylcholinesterase, increased p-Tau expression, and increased apoptosis. Cordycepin inhibits ROS production, elevated levels of Ca2+ induced by Aβ25-35, and the activation of acetylcholinesterase; all these are involved in oxidative-induced apoptosis. In addition, it decreases the increased p-Tau expression that plays a key role in the initiation of the AD. Results showed that the anti-apoptotic effects of cordycepin are partially dependent on the activation of adenosine A1 receptor, whereas an antagonist selectively attenuated the neuroprotective effects of cordycepin. Collectively, these results suggest that cordycepin could be a potential future therapeutic agent for neuronal disorders, such as AD.
    Keywords:  Adenosine A(1) receptor; Alzheimer’s disease; Apoptosis; Aβ(25–35); Cordycepin
  7. Biochim Biophys Acta. 2018 Jul 18. pii: S0925-4439(18)30262-X. [Epub ahead of print]
    Gao L, Liu Y, Guo S, Xiao L, Wu L, Wang Z, Liang C, Yao R, Zhang Y.
      Diabetes contributes to cardiovascular complications and the pathogenesis of cardiac remodeling that can lead to heart failure. We aimed to evaluate the functional role of LAZ3 in diabetic cardiomyopathy (DCM). Streptozotocin (STZ) was used to induce a diabetic mouse model. Three months after induction, the mice were subjected to retro-orbital venous plexus injection of adeno-associated virus 9 (AAV9) that overexpressed LAZ3. Six weeks after the infection, mouse hearts were removed to assess the degree of cardiac remodeling. LAZ3 was down-regulated in the diabetic mouse hearts and high glucose stimulated cardiomyocytes. Knock-down of LAZ3 in cardiomyocytes with LAZ3 siRNA reduced cell viability, increased the inflammatory response and induced oxidative stress and cell apoptosis. Overexpression of LAZ3 by infection with adeno-associated virus (AAV9)-LAZ3 protected against an inflammatory response, oxidative stress and cell apoptosis in both a high glucose stimulated in vitro study and diabetic mouse hearts. We found that LAZ3 increased the activation of PPARa, which increased PGC-1a activation and subsequently augmented NRF2 expression and nuclear translocation. This outcome was confirmed by NRF2 siRNA and a PPARa activator, since NRF2 siRNA abrogated the protective effects of LAZ3 overexpression, while the PPARa activator reversed the deteriorating phenotype of LAZ3 knock-down in both the in vitro and vivo study. Furthermore, LAZ3 decreased miR-21 expression, which resulted in PPARa activation, NRF2 expression and nuclear translocation. In conclusion, LAZ3 protects against cardiac remodeling in DCM by decreasing miR-21, thus regulating PPARa/NRF2 signaling.
    Keywords:  Cardiac remodeling; Diabetes; LAZ3; PPARa; miR-21
  8. Chemosphere. 2018 Jul 12. pii: S0045-6535(18)31314-6. [Epub ahead of print]210 633-644
    Wang XH, Zheng SS, Huang T, Su LM, Zhao YH, Souders CL, Martyniuk CJ.
      Fluazinam is a pyridinamine fungicide that induces oxidative stress and mitochondrial damage in cells, and it has been reported to be neurotoxic. To characterize the biological effects of fluazinam, we assessed mitochondrial bioenergetics, dopamine system expression, and behavior of early life staged zebrafish (0.01 μM-0.5 μM). Fluazinam at environmentally-relevant levels did not induce sub-lethal effects in larvae, but at the LC50 (0.5 μM), fluazinam decreased basal and ATP-linked respiration significantly in embryos. As mitochondria are directly related to redox homeostasis and apoptosis, the expression of genes related to oxidative stress and apoptosis were measured. Superoxide dismutase 2 (sod2), heat stock protein 70 (hsp70), bcl2-associated X protein (bax), and caspase 9 (casp9) mRNA levels were up-regulated by 0.5 μM fluazinam. Taken together, there was evidence for mitochondrial dysfunction and oxidative damage at the highest concentration of fluazinam (0.5 μM) tested. As there are reports for fluazinam-induced neurotoxicity in dopamine synthesizing cells, transcriptional targets in the dopamine system were assessed in the zebrafish. Tyrosine hydroxylase 1 (th1) and dopamine receptor 2a (drd2a) mRNA levels were decreased by 0.5 μM fluazinam, suggesting that this fungicide may affect the dopaminergic system. To further assess the potential for fluazinam-mediated neuromodulation, the dark photokinesis response was assessed in larvae following exposure. Larvae exposed to 0.1 μM fluazinam showed hyperactivity, while larvae exposed to 0.2 and 0.3 μM showed hypo-activity. This study demonstrates that fluazinam disrupts mitochondrial bioenergetics in zebrafish, inducing an oxidative stress response, and aberrant behaviors in larvae that are dose dependent.
    Keywords:  Aquatic toxicology; Fungicide; Locomotor activity; Mitochondrial bioenergetics; Oxidative stress
  9. Life Sci. 2018 Jul 18. pii: S0024-3205(18)30408-9. [Epub ahead of print]
    Zhou C, Lai Y, Huang P, Xie L, Lin H, Zhou Z, Mo C, Deng G, Yan W, Gao Z, Huang S, Chen Y, Sun X, Lv Z, Gao L.
      AIMS: Alcoholic liver disease (ALD) is a leading health risk worldwide, which can induce hepatic steatosis, progressive fibrosis, cirrhosis and even carcinoma. As a potential therapeutic drug for ALD, naringin, an abundant flavanone in grapefruit, could improve resistance to oxidative stress and inflammation and protects against multiple organ injury. However, the specific mechanisms responsible for protection against alcoholic injury remain not fully understood. In this study, we aim to investigate the effect and the regulatory mechanisms of naringin in the liver and whole body after alcohol exposure under zebrafish larvae system.MAIN METHODS: At 96 h post fertilization (hpf), larvae from wild-type (WT) and transgenic zebrafish, with liver-specific eGFP expression (Tg(lfabp10α:eGFP)), were exposed to 2% ethanol for 32 h to establish an ALD model. Different endpoints, such as morphological changes in liver shape and size, histological changes, oxidative stress-related free radical levels, apoptosis and the expression of certain genes, were chosen to verify the essential impact of naringin in alcohol-induced liver lesions.
    KEY FINDINGS: Subsequent experiments, including Oil red O, Nile red, pathological hematoxylin and eosin (H&E), and TUNEL staining and qPCR, revealed that naringin treatment reduced alcoholic hepatic steatosis, and this inhibitory effect was dose dependent. Specifically, a 25 mg/L dose resulted in an almost normal response.
    SIGNIFICANCE: This finding suggested that naringin may inhibit alcoholic-induced liver steatosis and injury by attenuating lipid accumulation and reducing oxidative stress and apoptosis.
    Keywords:  Alcohol-induced liver injury; Anti-apoptosis; Antioxidation; Naringin; Zebrafish larvae