Chikungunya virus–induced autophagy delays caspase-dependent cell death

Autophagy is an important survival pathway and can participate in the host response to infection. Studying Chikungunya virus (CHIKV), the causative agent of a major epidemic in India, Southeast Asia, and southern Europe, we reveal a novel mechanism by which autophagy limits cell death and mortality after infection. We use biochemical studies and single cell multispectral assays to demonstrate that direct infection triggers both apoptosis and autophagy. CHIKV-induced autophagy is mediated by the independent induction of endoplasmic reticulum and oxidative stress pathways. These cellular responses delay apoptotic cell death by inducing the IRE1α–XBP-1 pathway in conjunction with ROS-mediated mTOR inhibition. Silencing of autophagy genes resulted in enhanced intrinsic and extrinsic apoptosis, favoring viral propagation in cultured cells. Providing in vivo evidence for the relevance of our findings, Atg16LHM mice, which display reduced levels of autophagy, exhibited increased lethality and showed a higher sensitivity to CHIKV-induced apoptosis. Based on kinetic studies and the observation that features of apoptosis and autophagy were mutually exclusive, we conclude that autophagy inhibits caspase-dependent cell death but is ultimately overwhelmed by viral replication. Our study suggests that inducers of autophagy may limit the pathogenesis of acute Chikungunya disease.

Download Full-text

O-GlcNAc Transferase Inhibitor Synergistically Enhances Doxorubicin-Induced Apoptosis in HepG2 Cells

Cancers ◽

10.3390/cancers12113154 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3154

Author(s):

Su Jin Lee ◽

Oh-Shin Kwon

Keyword(s):

Hepatocellular Carcinoma ◽

Cell Death ◽

Hepg2 Cells ◽

Drug Targets ◽

Apoptotic Cell ◽

Chemotherapy Resistance ◽

Apoptotic Cell Death ◽

Induced Apoptosis ◽

Glcnac Transferase

The combination of chemotherapy with chemosensitizing agents is a common approach to enhance anticancer activity while reducing the dose-dependent adverse side effects of cancer treatment. Herein, we investigated doxorubicin (DOX) and O-GlcNAc transferase (OGT) inhibitor OSMI-1 combination treatment, which significantly enhanced apoptosis in hepatocellular carcinoma cells (HepG2) as a result of synergistic drug action in disparate stress signaling pathways. Treatment with a low dose of DOX or a suboptimal dose of OSMI-1 alone did not induce apoptotic cell death in HepG2 cells. However, the combination of DOX with OSMI-1 in HepG2 cells synergistically increased apoptotic cell death through the activation of both the p53 and mitochondrial Bcl2 pathways compared to DOX alone. We also demonstrated that the combination of DOX and OSMI-1 stimulated cell death, dramatically reducing cell proliferation and tumor growth in vivo using a HepG2 xenograft mouse model. These findings indicate that OSMI-1 acts as a potential chemosensitizer by enhancing DOX-induced cell death. This study provides insight into a possible mechanism of chemotherapy resistance, identifies potential novel drug targets, and suggests that OGT inhibition could be utilized in clinical applications to treat hepatocellular carcinoma as well as other cancer types.

Download Full-text

Functional Interaction of Hypoxia-Inducible Factor 2-Alpha and Autophagy Mediates Drug Resistance in Colon Cancer Cells

Cancers ◽

10.3390/cancers11060755 ◽

2019 ◽

Vol 11 (6) ◽

pp. 755 ◽

Cited By ~ 4

Author(s):

Abril Saint-Martin ◽

Jacobo Martínez-Ríos ◽

M. Cristina Castañeda-Patlán ◽

Miguel Angel Sarabia-Sánchez ◽

Nydia Tejeda-Muñoz ◽

...

Keyword(s):

Colon Cancer ◽

Drug Resistance ◽

Cell Death ◽

Cancer Cells ◽

Apoptotic Cell ◽

Malignant Cells ◽

Colon Cancer Cells ◽

Mtor Inhibition

Hypoxia and the accumulation of hypoxia-inducible factors (HIFs) in tumors have been associated with therapeutic resistance and with autophagy establishment. We examined the effects of stable knockdown of HIF-1α or HIF-2α expression on autophagy and drug resistance in colon cancer cells. We found that under normoxic conditions, malignant cells exhibit increased basal levels of autophagy, compared with non-malignant cells, in addition to the previously reported coexpression of HIF-1α and HIF-2α. Knockdown of HIF-1α or HIF-2α expression resulted in increased autophagic and apoptotic cell death, indicating that the survival of cells is HIF-dependent. Cytotoxic-induced cell death was significantly increased by knockdown of HIFs but not by autophagy inhibition. Strikingly, although malignancy-resistant cells were sensitized to death by nutrient stress, the combination with HIF-2α depletion, but not with HIF-1α depletion, induced severe cell death. Oxidative stress levels were significantly increased as a result of HIF-2α specific inhibition or silencing suggesting that this may contribute to sensitize cells to death. The in vitro results were confirmed in vivo using a xenograft mouse model. We found that coordinated autophagy and mTOR inhibition enhanced cell death and induced tumor remission only in HIF-2α-silenced cells. Finally, using a specific HIF-2α inhibitor alone or in combination with drugs in patient-derived primary colon cancer cells, overcame their resistance to 5-FU or CCI-779, thus emphasizing the crucial role played by HIF-2α in promoting resistance and cell survival.

Download Full-text

DNA nick end labeling: a reliable marker for apoptosis?

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141184 ◽

1995 ◽

Vol 53 ◽

pp. 962-963

Author(s):

Anne F. Bushnell ◽

Sarah Webster ◽

Lynn S. Perlmutter

Keyword(s):

Cell Death ◽

Cultured Cells ◽

Apoptotic Cell ◽

Morphological Characteristics ◽

Detection Methods ◽

Tissue Preparation ◽

Preparation Methods ◽

Dna Laddering ◽

Disease States ◽

Reliable Marker

Apoptosis, or programmed cell death, is an important mechanism in development and in diverse disease states. The morphological characteristics of apoptosis were first identified using the electron microscope. Since then, DNA laddering on agarose gels was found to correlate well with apoptotic cell death in cultured cells of dissimilar origins. Recently numerous DNA nick end labeling methods have been developed in an attempt to visualize, at the light microscopic level, the apoptotic cells responsible for DNA laddering.The present studies were designed to compare various tissue processing techniques and staining methods to assess the occurrence of apoptosis in post mortem tissue from Alzheimer's diseased (AD) and control human brains by DNA nick end labeling methods. Three tissue preparation methods and two commercial DNA nick end labeling kits were evaluated: the Apoptag kit from Oncor and the Biotin-21 dUTP 3' end labeling kit from Clontech. The detection methods of the two kits differed in that the Oncor kit used digoxigenin dUTP and anti-digoxigenin-peroxidase and the Clontech used biotinylated dUTP and avidinperoxidase. Both used 3-3' diaminobenzidine (DAB) for final color development.

Download Full-text

iPLA2β Contributes to ER Stress-Induced Apoptosis during Myocardial Ischemia/Reperfusion Injury

Cells ◽

10.3390/cells10061446 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1446

Author(s):

Tingting Jin ◽

Jun Lin ◽

Yingchao Gong ◽

Xukun Bi ◽

Shasha Hu ◽

...

Keyword(s):

Cell Death ◽

Heart Disease ◽

Myocardial Ischemia ◽

Ischemic Heart Disease ◽

Er Stress ◽

Ischemia Reperfusion ◽

Myocardial Ischemia Reperfusion ◽

Induced Apoptosis

Both calcium-independent phospholipase A2 beta (iPLA2β) and endoplasmic reticulum (ER) stress regulate important pathophysiological processes including inflammation, calcium homeostasis and apoptosis. However, their roles in ischemic heart disease are poorly understood. Here, we show that the expression of iPLA2β is increased during myocardial ischemia/reperfusion (I/R) injury, concomitant with the induction of ER stress and the upregulation of cell death. We further show that the levels of iPLA2β in serum collected from acute myocardial infarction (AMI) patients and in samples collected from both in vivo and in vitro I/R injury models are significantly elevated. Further, iPLA2β knockout mice and siRNA mediated iPLA2β knockdown are employed to evaluate the ER stress and cell apoptosis during I/R injury. Additionally, cell surface protein biotinylation and immunofluorescence assays are used to trace and locate iPLA2β. Our data demonstrate the increase of iPLA2β augments ER stress and enhances cardiomyocyte apoptosis during I/R injury in vitro and in vivo. Inhibition of iPLA2β ameliorates ER stress and decreases cell death. Mechanistically, iPLA2β promotes ER stress and apoptosis by translocating to ER upon myocardial I/R injury. Together, our study suggests iPLA2β contributes to ER stress-induced apoptosis during myocardial I/R injury, which may serve as a potential therapeutic target against ischemic heart disease.

Download Full-text

KUS121 attenuates the progression of monosodium iodoacetate-induced osteoarthritis in rats

Scientific Reports ◽

10.1038/s41598-021-95173-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sachiko Iwai ◽

Hanako O. Ikeda ◽

Hisashi Mera ◽

Kohei Nishitani ◽

Motoo Saito ◽

...

Keyword(s):

Cell Death ◽

Er Stress ◽

Apoptotic Cell ◽

Intraperitoneal Administration ◽

Atp Depletion ◽

Knee Joints ◽

Cellular Protection ◽

Monosodium Iodoacetate

AbstractCurrently there is no effective treatment available for osteoarthritis (OA). We have recently developed Kyoto University Substances (KUSs), ATPase inhibitors specific for valosin-containing protein (VCP), as a novel class of medicine for cellular protection. KUSs suppressed intracellular ATP depletion, endoplasmic reticulum (ER) stress, and cell death. In this study, we investigated the effects of KUS121 on chondrocyte cell death. In cultured chondrocytes differentiated from ATDC5 cells, KUS121 suppressed the decline in ATP levels and apoptotic cell death under stress conditions induced by TNFα. KUS121 ameliorated TNFα-induced reduction of gene expression in chondrocytes, such as Sox9 and Col2α. KUS121 also suppressed ER stress and cell death in chondrocytes under tunicamycin load. Furthermore, intraperitoneal administration of KUS121 in vivo suppressed chondrocyte loss and proteoglycan reduction in knee joints of a monosodium iodoacetate-induced OA rat model. Moreover, intra-articular administration of KUS121 more prominently reduced the apoptosis of the affected chondrocytes. These results demonstrate that KUS121 protects chondrocytes from stress-induced cell death in vitro and in vivo, and indicate that KUS121 is a promising novel therapeutic agent to prevent the progression of OA.

Download Full-text

Mitochondrion-Dependent Cell Death in TDP-43 Proteinopathies

Biomedicines ◽

10.3390/biomedicines9040376 ◽

2021 ◽

Vol 9 (4) ◽

pp. 376

Author(s):

Chantal B. Lucini ◽

Ralf J. Braun

Keyword(s):

Cell Death ◽

Oxygen Species ◽

In Vivo Models ◽

Dependent Cell ◽

Cell Death Mechanisms ◽

Sting Pathway ◽

Mitochondrial Membrane Permeabilization

In the last decade, pieces of evidence for TDP-43-mediated mitochondrial dysfunction in neurodegenerative diseases have accumulated. In patient samples, in vitro and in vivo models have shown mitochondrial accumulation of TDP-43, concomitantly with hallmarks of mitochondrial destabilization, such as increased production of reactive oxygen species (ROS), reduced level of oxidative phosphorylation (OXPHOS), and mitochondrial membrane permeabilization. Incidences of TDP-43-dependent cell death, which depends on mitochondrial DNA (mtDNA) content, is increased upon ageing. However, the molecular pathways behind mitochondrion-dependent cell death in TDP-43 proteinopathies remained unclear. In this review, we discuss the role of TDP-43 in mitochondria, as well as in mitochondrion-dependent cell death. This review includes the recent discovery of the TDP-43-dependent activation of the innate immunity cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING) pathway. Unravelling cell death mechanisms upon TDP-43 accumulation in mitochondria may open up new opportunities in TDP-43 proteinopathy research.

Download Full-text

4-Acetyl-12,13-Epoxyl-9-Trichothecene-3,15-Diol from Isaria japonica Mediates Apoptosis of Rat Bladder Carcinoma NBT-II Cells by Decreasing Anti-apoptotic Bcl-2 Expression and Increasing Pro-apoptotic Bax Expression

The American Journal of Chinese Medicine ◽

10.1142/s0192415x0400203x ◽

2004 ◽

Vol 32 (03) ◽

pp. 377-387 ◽

Cited By ~ 2

Author(s):

Hyung-Jin Kim ◽

Seon Il Jang ◽

Young-Jun Kim ◽

Hyun-Ock Pae ◽

Hae-Young Won ◽

...

Keyword(s):

Cell Death ◽

Bladder Carcinoma ◽

Cytotoxic Effect ◽

Caspase 3 ◽

Apoptotic Cell ◽

Morphological Changes ◽

Rat Bladder ◽

Apoptotic Protein ◽

Induction Of Apoptosis ◽

Induced Apoptosis

We studied the effect of 4-acetyl-12,13-epoxyl-9-trichothecene-3,15-diol (AETD) isolated from Isaria japonica, one of the most popular Chinese fungal medicines, on the induction of apoptosis in rat bladder carcinoma NBT-II cells. AETD was cytotoxic to NBT-II cells, and this cytotoxic effect appears to be attributed to its induction of apoptotic cell death, as AETD induced nuclear morphological changes and internucleosomal DNA fragmentation, and increased the proportion of hypodiploid cells and activity of caspase-3. AETD treatment also decreased the expression of the anti-apoptotic protein Bcl-2 and increased the expression of the pro-apoptotic protein Bax. These results provide important information in understanding the mechanism(s) of AETD-induced apoptosis.

Download Full-text

Mitochondrial Pathway of α-Tocopheryl Succinate-Induced Apoptosis in Human Epidermoid Carcinoma A431 Cells

Acta Naturae ◽

10.32607/20758251-2012-4-3-88-94 ◽

2012 ◽

Vol 4 (3) ◽

pp. 88-94 ◽

Cited By ~ 3

Author(s):

M. A. Savitskaya ◽

M. S. Vildanova ◽

O. P. Kisurina-Evgenieva ◽

E. A. Smirnova ◽

G. E. Onischenko

Keyword(s):

Cell Death ◽

Vitamin E ◽

Apoptotic Cell ◽

Mitochondrial Pathway ◽

Epidermoid Carcinoma ◽

A431 Cells ◽

Human Carcinoma ◽

Tocopheryl Succinate ◽

Induced Apoptosis ◽

Human Epidermoid Carcinoma

Vitamin E derivatives are known to act as agents exhibiting cytotoxity against tumor cells. The effect of vitamin E succinate on human epidermoid carcinoma cell line A431 was investigated in this study using live imaging, immunocytochemistry, and transmission electron microscopy. -Tocopheryl succinate-induced apoptotic cell death in A431 cells was shown to be both dose- and time-dependent. The hyperproduction of reactive oxygen species, changes in size, shape and ultrastructural characteristics of mitochondria followed by the release of cytochrome c from mitochondria to cytosol were observed. These results suggest that -tocopheryl succinate induces apoptosis that occurs via the mitochondrial pathway. Mitochondria are shown to be crucial targets in -tocopheryl succinate-induced caspase-dependent cell death in human carcinoma A431 cells.

Download Full-text

Contribution of TNF-α to Leukocyte Adhesion, Vascular Leakage, and Apoptotic Cell Death in Endotoxin-Induced Uveitis In Vivo

Investigative Opthalmology & Visual Science ◽

10.1167/iovs.02-0589 ◽

2003 ◽

Vol 44 (5) ◽

pp. 2184 ◽

Cited By ~ 91

Author(s):

Kan Koizumi ◽

Vassiliki Poulaki ◽

Sven Doehmen ◽

Gerhard Welsandt ◽

Sven Radetzky ◽

...

Keyword(s):

Cell Death ◽

Apoptotic Cell ◽

Leukocyte Adhesion ◽

Apoptotic Cell Death ◽

Vascular Leakage ◽

Tnf Α

Download Full-text

Isoflavones Isolated from the Seeds of Millettia ferruginea Induced Apoptotic Cell Death in Human Ovarian Cancer Cells

Molecules ◽

10.3390/molecules25010207 ◽

2020 ◽

Vol 25 (1) ◽

pp. 207 ◽

Cited By ~ 2

Author(s):

Yi-Yue Wang ◽

Jun Hyeok Kwak ◽

Kyung-Tae Lee ◽

Tsegaye Deyou ◽

Young Pyo Jang ◽

...

Keyword(s):

Ovarian Cancer ◽

Cell Death ◽

Cancer Cells ◽

Caspase 3 ◽

Apoptotic Cell ◽

Apoptotic Cell Death ◽

Ovarian Cancer Cells ◽

Human Ovarian Cancer ◽

Millettia Ferruginea ◽

Induced Apoptosis

The seeds of Millettia ferruginea are used in fishing, pesticides, and folk medicine in Ethiopia. Here, the anti-cancer effects of isoflavones isolated from M. ferruginea were evaluated in human ovarian cancer cells. We found that isoflavone ferrugone and 6,7-dimethoxy-3’,4’-methylenedioxy-8-(3,3-dimethylallyl)isoflavone (DMI) had potent cytotoxic effects on human ovarian cancer cell A2780 and SKOV3. Ferrugone and DMI treatment increased the sub-G1 cell population in a dose-dependent manner in A2780 cells. The cytotoxic activity of ferrugone and DMI was associated with the induction of apoptosis, as shown by an increase in annexin V-positive cells. Z-VAD-fmk, a broad-spectrum caspase inhibitor, and z-DEVD-fmk, a caspase-3 inhibitor, significantly reversed both the ferrugone and DMI-induced apoptosis, suggesting that cell death stimulated by the isoflavones is mediated by caspase-3-dependent apoptosis. Additionally, ferrugone-induced apoptosis was found to be caspase-8-dependent, while DMI-induced apoptosis was caspase-9-dependent. Notably, DMI, but not ferrugone, increased the intracellular levels of reactive oxygen species (ROS), and antioxidant N-acetyl-L-cysteine (NAC) attenuated the pro-apoptotic activity of DMI. These data suggest that DMI induced apoptotic cell death through the intrinsic pathway via ROS production, while ferrugone stimulated the extrinsic pathway in human ovarian cancer cells.

Download Full-text