benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and 3-methyladenine

This study aimed to explore the mechanism of impaired autophagy flux induced by exendin-4 and its role on cell apoptosis in pancreatic AR42J cells. The AR42J cells were treated with various concentration of exendin-4 for several time points to assess its cytotoxicity by MTT assay. Then the AR42J cells were treated by 10pM exendin-4 for 72 h, the cell death was analyzed by flow cytometry and caspase-3 level was examined by Western blot with or without the pretreatment of z-VAD-fmk to testify whether exendin-4 induces the cell apoptosis. The protein levels of LC3B, p62 and LAMP-2 were assessed by Western blot, the mRNA level of LAMP-2 was quantified by quantitative PCR in the absence or presence of LAMP-2 over-expression plasmid and the expression and activity of CatB and CatL were tested by ELISA or activity assay methods in AR42J cells treated by exendin-4. The normal rats and the diabetes-model rats by high-fat and high-sugar diet for two month then with streptozotocin intraperitoneally were subcutaneously injected with exendin-4 for 10 weeks to test the expression of LAMP-2 mRNA and protein in the pancreas. Cells pretreated with Bafilomycin A1 were detected for LC3B and p62 expressions by Western blot. Cells pretreated by 3-MA were used to assess whether 3-MA can protect from exendin-4 cytotoxicity. We found that exendin-4 can decrease the AR42J cell viability as well as increase the cell death and cleaved caspase-3 level, which all can be inhibited by z-VAD-fmk. Exendin-4 can downregulate the expression of LAMP-2 and then impair the autophagy flux to induce the accumulation of LC3B-II and p62, but cannot change the expression and activity of CatB and CatL. Bafilomycin A1 almostly have no impact on the change of LC3B and p62 protein levels induced by exendin-4. Both 3-MA and overexpressed LAMP-2 can reduce the cytotoxicity of exendin-4. Therefore, we considered the down-regulation of LAMP-2 which can impair the autophagy flux by inhibiting the fusion of autophagosomes with lysosomes to induce the AR42J cell apoptosis as the potential mechanism of chronic pancreatitis induced by exendin-4.

Topics: Acinar Cells; Adenine; Amino Acid Chloromethyl Ketones; Animals; Autophagy; Caspase 3; Cathepsin B; Cathepsin L; Cell Line; Diabetes Mellitus, Experimental; Diet, High-Fat; Exenatide; Gene Expression Regulation; Lysosomal-Associated Membrane Protein 2; Macrolides; Male; Microtubule-Associated Proteins; Pancreas; Peptides; Rats; Rats, Sprague-Dawley; Sequestosome-1 Protein; Signal Transduction; Streptozocin; Venoms

Juglone (JG), a naturally-occurring naphthoquinone of Manchurian walnut (Juglans mandshurica) was shown to inhibit proliferation in various tumor types. However, the molecular mechanisms of JG on the induction of apoptosis and autophagy in HepG2 cells have not been examined. Herein, we investigated that JG could inhibit cell proliferation by induction of G2/M phase arrest. Also, occurrence of apoptosis was closely related with loss of mitochondrial membrane potential, the changes of apoptosis-related proteins after treatment with JG. In addition, we found that JG caused autophagy, as evidenced by increased expressions of LC3-II and Beclin-1. Interestingly, inhibition of JG-induced autophagy by 3-methyladenine (3-MA) and wortmannin (WT) significantly decreased apoptosis, whereas the apoptosis inhibitor z-VAD-fmk slightly enhanced autophagy. Furthermore, the induction of autophagy and apoptosis was associated with activation of MAPK family members (p38 and JNK) and production of reactive oxygen species (ROS). Both JNK inhibitor (SP600125) and ROS scavenger (N-acetylcysteine, NAC) could attenuate JG-induced autophagy and apoptosis. However, the p38-specific inhibitor SB203580 enhanced autophagic and apoptotic death. Moreover, the ROS scavenger NAC prevented phosphorylation of both p38 and JNK. Collectively, our data revealed that JG induced G2/M phase arrest, apoptosis, and autophagy through the ROS-dependent signaling pathway.

Topics: Acetylcysteine; Adenine; Amino Acid Chloromethyl Ketones; Androstadienes; Apoptosis; Autophagy; Carcinoma, Hepatocellular; Cell Cycle Checkpoints; Cell Proliferation; Enzyme Activation; Hep G2 Cells; Humans; Liver Neoplasms; MAP Kinase Kinase 4; MAP Kinase Signaling System; Membrane Potential, Mitochondrial; Naphthoquinones; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Reactive Oxygen Species; Wortmannin

Lung cancer is a prevalent disease and is one of the leading causes of mortality worldwide. Despite the development of various anticancer drugs, the prognosis of lung cancer is relatively poor. Metastasis of lung cancer, as well as chemoresistance, is associated with a high mortality rate for patients with lung cancer. Camptothecin (CPT) is a well-known anticancer drug, which causes cancer cell apoptosis via the induction of DNA damage; however, the cytotoxicity of CPT easily reaches a plateau at a relatively high dose in lung cancer cells, thus limiting its efficacy. The present study demonstrated that CPT may induce autophagy in two human non‑small cell lung cancer cell lines, H1299 and H460. In addition, the results of a viability assay and Annexin V staining revealed that CPT-induced autophagy could protect lung cancer cells from programmed cell death. Conversely, the cytotoxicity of CPT was increased when autophagy was blocked by 3-methyladenine treatment. Furthermore, inhibition of autophagy enhanced the levels of CPT-induced DNA damage in the lung cancer cell lines. Accordingly, these findings suggested that autophagy exerts a protective role in CPT-treated lung cancer cells, and the combination of CPT with a specific inhibitor of autophagy may be considered a promising strategy for the future treatment of lung cancer.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Antineoplastic Agents, Phytogenic; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Autophagy; Camptothecin; Carcinoma, Non-Small-Cell Lung; Caspase Inhibitors; Cell Line, Tumor; Cell Movement; DNA Damage; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Histones; Humans; Inhibitory Concentration 50; Lung Neoplasms

The Helicobacter pylori vacuolating cytotoxin (VacA) can promote progressive vacuolation and gastric injury and may be associated with human gastric cancer. Increasing evidence indicates that autophagy is involved in the cell death induced by VacA, but the specific mechanisms need to be further elucidated. We show here that VacA could induce autophagy and increase cell death in human gastric cancer cell lines. Further investigations revealed that inhibition of autophagy could decrease the VacA-induced cell death in AGS cells. Furthermore, numerous dilated endoplasmic reticula (ER) were observed, and the phosphorylation of a subunit of eukaryotic translation initiation factor 2 subunit 1 also increased in the VacA-treated AGS cells, while repression of ER stress could reduce autophagy and cell death through knockdown of activating transcription factor 4 and DNA-damage-inducible transcript 3. In addition, the expression of pseudokinase tribbles homolog 3 (TRIB3) upon ER stress was triggered by VacA, and knockdown of TRIB3 could also decrease VacA-induced cell death. Finally, inhibition of autophagy could decrease VacA

Topics: Activating Transcription Factor 4; Adenine; Amino Acid Chloromethyl Ketones; Animals; Autophagy; Bacterial Proteins; Cell Cycle Proteins; Cell Line, Tumor; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Epithelial Cells; Eukaryotic Initiation Factor-2; Gene Expression Regulation, Neoplastic; Helicobacter pylori; Humans; Macrolides; Mice; Poly (ADP-Ribose) Polymerase-1; Protein Serine-Threonine Kinases; Repressor Proteins; RNA, Small Interfering; Signal Transduction; Thapsigargin; Transcription Factor CHOP; Vacuoles

Intra-retinal extravasation and modification of LDL have been implicated in diabetic retinopathy: autophagy may mediate these effects.. Immunohistochemistry was used to detect autophagy marker LC3B in human and murine diabetic and non-diabetic retinas. Cultured human retinal capillary pericytes (HRCPs) were treated with in vitro-modified heavily-oxidised glycated LDL (HOG-LDL) vs native LDL (N-LDL) with or without autophagy modulators: green fluorescent protein-LC3 transfection; small interfering RNAs against Beclin-1, c-Jun NH(2)-terminal kinase (JNK) and C/EBP-homologous protein (CHOP); autophagy inhibitor 3-MA (5 mmol/l) and/or caspase inhibitor Z-VAD-fmk (100 μmol/l). Autophagy, cell viability, oxidative stress, endoplasmic reticulum stress, JNK activation, apoptosis and CHOP expression were assessed by western blots, CCK-8 assay and TUNEL assay. Finally, HOG-LDL vs N-LDL were injected intravitreally to STZ-induced diabetic vs control rats (yielding 50 and 200 mg protein/l intravitreal concentration) and, after 7 days, retinas were analysed for ER stress, autophagy and apoptosis.. Intra-retinal autophagy (LC3B staining) was increased in diabetic vs non-diabetic humans and mice. In HRCPs, 50 mg/l HOG-LDL elicited autophagy without altering cell viability, and inhibition of autophagy decreased survival. At 100-200 mg/l, HOG-LDL caused significant cell death, and inhibition of either autophagy or apoptosis improved survival. Further, 25-200 mg/l HOG-LDL dose-dependently induced oxidative and ER stress. JNK activation was implicated in autophagy but not in apoptosis. In diabetic rat retina, 50 mg/l intravitreal HOG-LDL elicited autophagy and ER stress but not apoptosis; 200 mg/l elicited greater ER stress and apoptosis.. Autophagy has a dual role in diabetic retinopathy: under mild stress (50 mg/l HOG-LDL) it is protective; under more severe stress (200 mg/l HOG-LDL) it promotes cell death.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Autophagy; Beclin-1; Cell Survival; Diabetic Retinopathy; Endoplasmic Reticulum Stress; Glycation End Products, Advanced; Humans; Immunohistochemistry; Lipoproteins, LDL; MAP Kinase Signaling System; Mice; Oxidation-Reduction; Oxidative Stress; Pericytes; Retina; Transcription Factor CHOP

Enterocytes die during high-dose radiation exposure in radiation accidents. The modality of cell death has a profound effect on the therapeutic response. The ilea from mice with 15 Gy total body irradiation (TBI) were drawn, morphological features observed by hematoxylin and eosin staining and transmission electron micrographs. The biochemical features of mouse ileum presented with the structure were cleaved Caspase-3 (apoptosis marker), Light Chain 3 (LC3)-I's conversion to LC3-II (autophagy marker) and high mobility group box chromosomal protein 1's secretion (necrosis marker). Then, the autophagy inhibitor (3-methyladenine), caspase inhibitor (Z-VAD-FMK) or necrosis inhibitor (necrostatin) was used to prevent death. Apoptosis, autophagy and necrosis were all appeared in the ileum, but necrosis had the biggest size; the use of 3-methyladenine and Z-VAD-FMK prolong one day's life of the mice after 15 Gy TBI, necrostatin significantly extended the lifespan of 15 Gy irradiated mice (p < 0.05). The results suggest that the death of enterocytes could not be classified into one type of cell death but rather as 'mixed death.'

Topics: Adenine; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Autophagy; Body Weight; Caspase 3; Caspase Inhibitors; Enterocytes; Enzyme Inhibitors; Feces; HMGB1 Protein; Imidazoles; Indoles; Intestinal Mucosa; Intestines; Male; Mice, Inbred C57BL; Necrosis; Radiation Dosage; Reactive Oxygen Species; Whole-Body Irradiation

Herein, inhibition of hepatocyte growth factor receptor, c-Met, significantly increased cytochrome c release and Bax/Bcl-2 ratio, indicating that c-Met played an anti-apoptotic role. The following experiments are to elucidate this anti-apoptotic mechanism, then the effect of c-Met on autophagy has also been discussed.. Investigated was the influence of c-Met on apoptosis, autophagy and loss of mitochondrial transmembrane potential (Δψm), and the relevant proteins were examined.. First, we found that activation of extracellular signal-regulated kinase (ERK), p53 was promoted by c-Met interference. Subsequent studies indicated that ERK was the upstream effector of p53, and this ERK-p53 pathway mediated release of cytochrome c and up-regulation of Bax/Bcl-2 ratio. Secondly, the inhibition of c-Met augmented oridonin-induced loss of mitochondrial transmembrane potential (Δψm), resulting apoptosis. Finally, the inhibition of c-Met increased oridonin-induced A549 cell autophagy accompanied by Beclin-1 activation and conversion from microtubule-associated protein light chain 3 (LC3)-I to LC3-II. Activation of ERK-p53 was also detected in autophagy process and could be augmented by inhibition of c-Met. Moreover, suppression of autophagy by 3-methyladenine (3-MA) or small interfering RNA against Beclin-1 or Atg5 decreased oridonin-induced apoptosis. Inhibition of apoptosis by pan-caspase inhibitor (z-VAD-fmk) decreased oridonin-induced autophagy as well and Loss of Δψm also occurred during autophagic process.. Thus, inhibiting c-Met enhanced oridonin-induced apoptosis, autophagy and loss of Δψm in A549 cells.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Autophagy-Related Protein 5; bcl-2-Associated X Protein; Beclin-1; Cytochromes c; Diterpenes, Kaurane; Extracellular Signal-Regulated MAP Kinases; Humans; Isodon; Lung Neoplasms; Membrane Potential, Mitochondrial; Membrane Proteins; Microtubule-Associated Proteins; Mitochondria; Phytotherapy; Plant Extracts; Proto-Oncogene Proteins c-met; RNA, Small Interfering; Tumor Suppressor Protein p53

Klotho has been identified as a tumor suppressor in several human malignancies including hepatocellular carcinoma (HCC). However, the signaling pathways involved in the tumor suppressive role of klotho in HCC have not been reported. Here, we investigated the role of klotho in HCC cell proliferation, apoptosis, autophagy, and invasion, as well as its associated signal transduction pathways.. Restoration of klotho gene expression was established by delivering a klotho gene expression vector into the human HCC cell lines HepG2 and MHCC-97-H. Cell viability was measured using a cell counting (CCK-8) assay and apoptosis was analyzed through flow cytometry. Autophagy was measured via LC3-I and LC3-II protein expression levels and tumor cell invasion was assessed using a Matrigel invasion chamber assay. Expression and phosphorylation of several apoptosis and survival related proteins were assessed using Western blot assays.. Exogenous klotho gene expression significantly inhibited HCC cell proliferation, induced HCC cell apoptosis, increased LC3-I and LC3-II protein expression in HCC cells, and decreased migration of HCC cells in a Matrigel invasion chamber assay. Exogenous klotho gene expression also down-regulated the phosphorylation levels of the IGF-1 receptor, and the downstream Akt, ERK, and p70S6K proteins. Both apoptosis and autophagy inhibitors decreased klotho-induced apoptosis and autophagy.. Klotho is a tumor suppressor that, through the regulation of IGF-1R phosphorylation and subsequent activation of downstream Akt-p70S6K and ERK signaling, regulates HCC tumor cell proliferation, apoptosis, autophagy and invasion.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Apoptosis; Autophagy; Blotting, Western; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Movement; Cell Survival; Extracellular Signal-Regulated MAP Kinases; Flow Cytometry; Gene Expression Regulation, Neoplastic; Glucuronidase; Hep G2 Cells; Humans; Klotho Proteins; Liver Neoplasms; Microtubule-Associated Proteins; Proto-Oncogene Proteins c-akt; Receptor, IGF Type 1; Reverse Transcriptase Polymerase Chain Reaction; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; Transfection

Autophagy is a dynamic and highly regulated process of self-digestion responsible for cell survival and reaction to oxidative stress. As oxidative stress is increased in uremia and is associated with vascular calcification, we studied the role of autophagy in vascular calcification induced by phosphate. In an in vitro phosphate-induced calcification model of vascular smooth muscle cells (VSMCs) and in an in vivo model of chronic renal failure, autophagy was inhibited by the superoxide dismutase mimic MnTMPyP, superoxide dismutase-2 overexpression, and by knockdown of the sodium-dependent phosphate cotransporter Pit1. Although phosphate-induced VSMC apoptosis was reduced by an inhibitor of autophagy (3-methyladenine) and knockdown of autophagy protein 5, calcium deposition in VSMCs was increased during inhibition of autophagy, even with the apoptosis inhibitor Z-VAD-FMK. An inducer of autophagy, valproic acid, decreased calcification. Furthermore, 3-methyladenine significantly promoted phosphate-induced matrix vesicle release with increased alkaline phosphatase activity. Thus, autophagy may be an endogenous protective mechanism counteracting phosphate-induced vascular calcification by reducing matrix vesicle release. Therapeutic agents influencing the autophagic response may be of benefit to treat aging or disease-related vascular calcification and osteoporosis.

Topics: Adenine; Alkaline Phosphatase; Amino Acid Chloromethyl Ketones; Animals; Antioxidants; Autophagy; Autophagy-Related Protein 5; Caspase Inhibitors; Cattle; Cells, Cultured; Disease Models, Animal; Kidney Failure, Chronic; Metalloporphyrins; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Phosphates; Proteins; Rats; RNA Interference; Secretory Vesicles; Sodium-Phosphate Cotransporter Proteins, Type III; Superoxide Dismutase; Time Factors; Transfection; Valproic Acid; Vascular Calcification

Autophagy appears to play an important role in the normal development and maintenance of homeostasis in a variety of tissues, including the female reproductive tract. However, the role of autophagy and the association between autophagy and apoptosis in cyclic remodeling of the human endometrium have not been described. Therefore, we investigated the involvement of autophagy during the human endometrial cycle and its association with apoptosis. Endometrial samples were obtained from 15 premenopausal, nonpregnant women who underwent hysterectomies for benign gynecological reasons. The autophagy-associated protein, microtubule-associated protein 1 light chain 3 alpha (MAP1LC3A), was immunolocalized, and its expression level was measured by Western blot analysis. Apoptosis was evaluated by measuring the expression level of cleaved caspase 3 protein. MAP1LC3A protein was primarily expressed within the endometrial glandular cells and increased during the secretory phase. The expression level of the membrane-bound form of MAP1LC3A (MAP1LC3A-II) also increased as the menstrual cycle progressed, reaching a maximum level during the late secretory phase. This pattern coincided with the expression of cleaved caspase 3. Furthermore, expression of MAP1LC3A-II and cleaved caspase 3 increased in the in vitro-cultured endometrial cancer cells when estrogen and/or progesterone were withdrawn from the culture media to mimic physiological hormonal changes. These findings suggest that endometrial cell autophagy is directly involved in the cyclic remodeling of the human endometrium and is correlated with apoptosis. In addition, we inhibited autophagic processes using 3-methyladenine (3-MA) or bafilomycin A1 (Baf A1) to evaluate the role of autophagy in apoptosis induction in endometrial cancer cells. While the inhibition of autophagosome formation using 3-MA did not decrease apoptosis or cell death, the inhibition of autophagosome degradation by fusion with lysosomes using Baf A1 increased apoptosis and cell death, suggesting that the accumulation of autophagosomes induces apoptosis. Furthermore, Baf A1-induced apoptotic cell death was decreased by the apoptosis inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK). In conclusion, these results indicate that autophagy is involved in the endometrial cell cycle affecting apoptosis and is most prominent during the late secretory phase.

Topics: Adenine; Adult; Amino Acid Chloromethyl Ketones; Apoptosis; Autophagy; bcl-2-Associated X Protein; Caspase 3; Cell Cycle; Cells, Cultured; Endometrium; Female; Homeostasis; Humans; Macrolides; Menstrual Cycle; Microtubule-Associated Proteins; Middle Aged; Proto-Oncogene Proteins c-bcl-2

The ubiquitin-proteasome system and autophagy-lysosome system are 2 major protein degradation pathways in eukaryotic cells, which are tightly linked to cancer. Proteasome inhibitors have been approved in clinical use against hematologic malignancies, but their application in solid tumors is uncertain. Moreover, the role of autophagy after proteasome inhibition is controversial.. Two proteasome inhibitors, 2 autophagy inhibitors, and 3 hepatocellular carcinoma (HCC) cell lines were investigated in the current study. In vitro, cell proliferation was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell apoptosis was evaluated by flow cytometry analysis of annexin-V/propidium iodide staining, and autophagy was evaluated by green fluorescent protein-light chain 3 (GFP-LC3) redistribution and LC3 Western blot analysis. In vivo, Ki-67 staining was used to detect cell proliferation, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining was used to detect apoptosis, and electron microscopy and p62 immunohistochemical staining were used to detect autophagy.. Proteasome inhibitors suppressed proliferation, induced apoptosis, and activated autophagy in HCC cell lines in vitro, and autophagy exerted a protective role after proteasome inhibition. In vivo, anticancer effects of bortezomib on the MHCC-97H orthotopic model (human HCC cells) were different from the effects observed on the Huh-7 subcutaneous model (human HCC cells). The autophagy inhibitor chloroquine interacted synergistically with bortezomib to suppress proliferation and induce apoptosis in both tumor models.. The current results indicated that simultaneous targeting of the proteasome and autophagy pathways may represent a promising method for HCC treatment.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Beclin-1; Boronic Acids; Bortezomib; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Chloroquine; Cysteine Proteinase Inhibitors; Humans; Leupeptins; Membrane Proteins; Microtubule-Associated Proteins; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Pyrazines

Arsenic trioxide (arsenite) was the first chemotherapeutic drug to be described and is now being rediscovered in cancer treatment, including glioblastoma multiforme. Arsenite toxicity triggers autophagy in cancer cells, although final stages of the process involve executive caspases, suggesting an interplay between autophagic and apoptotic pathways that awaits to be explained at a molecular level. We evaluated the contribution of the lysosomal cathepsins (Cat) L and B, which are upregulated in glioblastomas, in the mechanism of arsenite toxicity in human glioblastoma cells. Arsenite treatment induced autophagosome formation and permeabilization of mitochondria, followed by caspase 3/7-mediated apoptosis. The autophagy inhibitor 3-methyladenine protected from arsenite toxicity, whereas bafilomycin A1 did not. Furthermore, arsenite significantly decreased CatB levels and selectively inhibited its cellular and recombinant protein activity, while not affecting CatL. However, downregulation of CatL greatly enhanced apoptosis by arsenite. Our results show that arsenite toxicity involves a complex interplay between autophagy and apoptosis in human glioblastoma cells and is associated with inhibition of CatB, and that this toxicity is highly exacerbated by simultaneous CatL inhibition. The latter points to a synergy that could be used in clinical treatment to lower the therapeutic dose, thus avoiding the toxic side effects of arsenite in glioblastoma management.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Arsenic Trioxide; Arsenicals; Autophagy; Caspases; Cathepsin B; Cathepsin L; Cell Line, Tumor; Dipeptides; Down-Regulation; Epoxy Compounds; Glioblastoma; Humans; Macrolides; Oxides; Pyridines

Autophagy is a process to engulf aberrant organelles or protein aggregates into double-membrane vesicles for lysosomal breakdown. Autophagy is a protective process against some intracellular bacteria and viruses; however, it is also used for replication by some viruses, such as poliovirus. We recently found that coxsackievirus B4 (CVB4) also induces the autophagy pathway and activates the calpain system for replication in neurons. Notably, the inhibition of autophagy with 3-methyladenine (3MA) reduced calpain activation and virus replication. Calpain inhibitors also reduced autophagosome formation and virus replication. This finding indicates that calpain and the autophagy pathway are closely connected with each other during the infection. Interestingly, we also found that 3MA and calpain inhibitors enhanced the caspase-3 specific cleavage of spectrin during CVB4 infection, suggesting that autophagy inhibition by these drugs triggered apoptosis. Thus, autophagy and apoptosis may balance each other in CVB4-infected neurons. Here, we show that inhibition of caspase with zVAD increased autophagosome formation, further proposing the cross-talk between autophagy and apoptosis in CVB4-infected neurons.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Autophagy; Calpain; Caspases; Coxsackievirus Infections; Cysteine Proteinase Inhibitors; Models, Biological; Neurons; Rats; Sirolimus; Virus Replication

It has been reported that ischemic insult increases the formation of autophagosomes and activates autophagy. However, the role of autophagy in ischemic neuronal damage remains elusive. This study was taken to assess the role of autophagy in ischemic brain damage. Focal cerebral ischemia was introduced by permanent middle cerebral artery occlusion (pMCAO). Activation of autophagy was assessed by morphological and biochemical examinations. To determine the contribution of autophagy/lysosome to ischemic neuronal death, rats were pretreated with a single intracerebral ventricle injection of the autophagy inhibitors 3-methyl-adenine (3-MA) and bafliomycin A1 (BFA) or the cathepsin B inhibitor Z-FA-fmk after pMCAO. The effects of 3-MA and Z-FA-fmk on brain damage, expression of proteins involved in regulation of autophagy and apoptosis were assessed with 2,3,5-triphenyltetrazolium chloride (TTC) staining and immunoblotting. The results showed that pMACO increased the formation of autophagosomes and autolysosomes, the mRNA and protein levels of LC3-II and the protein levels of cathepsin B. 3-MA, BFA and Z-FA-fmk significantly reduced infarct volume, brain edema and motor deficits. The neuroprotective effects of 3-MA and Z-FA-fmk were associated with an inhibition on ischemia-induced upregulation of LC3-II and cathepsin B and a partial reversion of ischemia-induced downregulation of cytoprotective Bcl-2. These results demonstrate that ischemic insult activates autophagy and an autophagic mechanism may contribute to ischemic neuronal injury. Thus, autophagy may be a potential target for developing a novel therapy for stroke.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Animals; Autophagy; Biomarkers; Brain; Brain Ischemia; Cathepsin B; Cysteine Proteinase Inhibitors; Humans; Infarction, Middle Cerebral Artery; Lysosomes; Male; Neurons; Neuroprotective Agents; Phagosomes; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Signal Transduction

Autophagy is a self-digestion process that degrades intracellular structures in response to stresses leading to cell survival. When autophagy is prolonged, this could lead to cell death. Generation of reactive oxygen species (ROS) through oxidative stress causes cell death. The role of autophagy in oxidative stress-induced cell death is unknown. In this study, we report that two ROS-generating agents, hydrogen peroxide (H(2)O(2)) and 2-methoxyestradiol (2-ME), induced autophagy in the transformed cell line HEK293 and the cancer cell lines U87 and HeLa. Blocking this autophagy response using inhibitor 3-methyladenine or small interfering RNAs against autophagy genes, beclin-1, atg-5 and atg-7 inhibited H(2)O(2) or 2-ME-induced cell death. H(2)O(2) and 2-ME also induced apoptosis but blocking apoptosis using the caspase inhibitor zVAD-fmk (benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone) failed to inhibit autophagy and cell death suggesting that autophagy-induced cell death occurred independent of apoptosis. Blocking ROS production induced by H(2)O(2) or 2-ME through overexpression of manganese-superoxide dismutase or using ROS scavenger 4,5-dihydroxy-1,3-benzene disulfonic acid-disodium salt decreased autophagy and cell death. Blocking autophagy did not affect H(2)O(2)- or 2-ME-induced ROS generation, suggesting that ROS generation occurs upstream of autophagy. In contrast, H(2)O(2) or 2-ME failed to significantly increase autophagy in mouse astrocytes. Taken together, ROS induced autophagic cell death in transformed and cancer cells but failed to induce autophagic cell death in non-transformed cells.

Topics: 2-Methoxyestradiol; Adenine; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Astrocytes; Autophagy; Cell Line, Transformed; Cell Line, Tumor; Cysteine Proteinase Inhibitors; Estradiol; HeLa Cells; Humans; Hydrogen Peroxide; Mice; Oxidants; Oxidative Stress; Reactive Oxygen Species; RNA, Small Interfering; Tubulin Modulators

Cnidarian bleaching results from the breakdown in the symbiosis between the host cnidarian and its dinoflagellate symbiont. Coral bleaching in recent years has increasingly caused degradation and mortality of coral reefs on a global scale. Although much is understood about the environmental causes of bleaching, the underlying cellular mechanisms of symbiont release that drive the process are just beginning to be described. In this study, we investigated the roles of two cellular pathways, host cell apoptosis and autophagy, in the bleaching process of the symbiotic anemone Aiptasia pallida. Host cell apoptosis was experimentally manipulated using gene knockdown of an anemone caspase by RNA interference, chemical inhibition of caspase using ZVAD-fmk and an apoptosis-inducer wortmannin. Autophagy was manipulated by chemical inhibition using wortmannin or induction using rapamycin. The applications of multiple single treatments resulted in some increased bleaching in anemones under control conditions but no significant drop in bleaching in individuals subjected to a hyperthermic stress. These results indicated that no single pathway is responsible for symbiont release during bleaching. However, when multiple inhibitors were applied simultaneously to block both apoptosis and autophagy, there was a significant reduction in bleaching in heat-stressed anemones. Our results allow us to formulate a model for cellular processes involved in the control of cnidarian bleaching where apoptosis and autophagy act together in a see-saw mechanism such that if one is inhibited the other is induced. Similar interconnectivity between apoptosis and autophagy has previously been shown in vertebrates including involvement in an innate immune response to pathogens and parasites. This suggests that the bleaching response could be a modified immune response that recognizes and removes dysfunctional symbionts.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Androstadienes; Animals; Apoptosis; Autophagy; Dinoflagellida; Dose-Response Relationship, Drug; Hot Temperature; RNA Interference; Sea Anemones; Sirolimus; Symbiosis; Wortmannin

Emerging lines of evidence show that the mechanisms of neurite degeneration are convergent, with poor neuritic transport, mitochondrial dysfunction and an increase in intra-axonal calcium being the principal convergence points. Nevertheless, the details are unclear. Here, we revealed the induction of autophagy in degenerating neurites of sympathetic neuron initiated by three different experimental paradigms. Autophagosomes were colocalized with collapsed cytoskeletal proteins in neuritic beadings during degeneration. Accumulation of microtubule-associated protein light chain 3-II, which is the most reliable marker for autophagy, was observed in the early stage of neurite degeneration. The autophagy inhibitor 3-methyladenine efficiently suppressed neurite degeneration by protecting neurites from the loss of viability and mitochondrial function. Furthermore, knocking down the key autophagy-related genes Atg7 and Beclin1 significantly delayed axonal and dendritic degeneration after nerve growth factor deprivation. Reduced expression of Atg7 also suppressed neurite fragmentation after transection. Therefore, our present data suggest the critical role of autophagy in neurite degeneration and may provide a valuable clue in understanding the mechanism of axonal and dendritic degeneration.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Animals; Apoptosis Regulatory Proteins; Autophagy; Autophagy-Related Protein 7; Beclin-1; Cells, Cultured; Gene Expression Regulation; Membrane Potential, Mitochondrial; Mice; Mice, Inbred C57BL; Microtubule-Associated Proteins; Nerve Degeneration; Nerve Growth Factor; Neurites; Neurons; Neuroprotective Agents; Proteins; Rats; RNA Interference; Superior Cervical Ganglion; Time Factors; Transfection

Previous studies reported that the neurotoxin, Crotoxin, isolated from the venom of South American rattlesnake had potent anti-tumor activity. Here, we investigated the involvement of autophagy and apoptosis in the Crotoxin-induced death of chronic myeloid leukemia cell line K562 cells. The neurotoxin dose dependently inhibited the viability of K562 cells. Crotoxin stimulated the autophagic activity as evidenced by the appearance of punctuate monodansylcadaverine (MDC) fluorescence staining in the cytoplasm and increased the formation of autophagosomes. Crotoxin caused the collapse of the mitochondrial membrane potential, release of cytochrome c and activation of caspase-3. Caspase inhibitors attenuated Crotoxin-induced K562 cell death, while blockage of autophagy maturation with 3-methyladenine (3-MA) and NH4Cl potentiated the neurotoxin's cytotoxicity. These results suggest that an apoptotic mechanism contributes to the Crotoxin-induced death of K562 cells, while the activation of autophagy delays neurotoxin-induced apoptosis.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Ammonium Chloride; Apoptosis; Autophagy; Caspase 3; Caspase Inhibitors; Caspases; Cell Survival; Crotoxin; Cytochromes c; Enzyme Activation; Humans; K562 Cells; Lysosomes; Mitochondria; Oligopeptides; Vacuoles

Apoptotic and autophagic cell death have been implicated, on the basis of morphological and biochemical criteria, in neuronal loss occurring in neurodegenerative diseases and it has been shown that they may overlap. We have studied the relationship between apoptosis and autophagic cell death in cerebellar granule cells (CGCs) undergoing apoptosis following serum and potassium deprivation. We found that apoptosis is accompanied by an early and marked proliferation of autophagosomal-lysosomal compartments as detected by electron microscopy and immunofluorescence analysis. Autophagy is blocked by hrIGF-1 and forskolin, two well-known inhibitors of CGC apoptosis, as well as by adenovirus-mediated overexpression of Bcl-2. 3-Methyladenine (3-MA) an inhibitor of autophagy, not only arrests this event but it also blocks apoptosis. The neuroprotective effect of 3-MA is accompanied by block of cytochrome c (cyt c) release in the cytosol and by inhibition of caspase-3 activation which, in turn, appears to be mediated by cathepsin B, as CA074-Me, a selective inhibitor of this enzyme, fully blocks the processing of pro-caspase-3. Immunofluorescence analysis demonstrated that cathepsin B, normally confined inside the lysosomal-endosomal compartment, is released during apoptosis into the cytosol where this enzyme may act as an execution protease. Collectively, these observations indicate that autophagy precedes and is causally connected with the subsequent onset of programmed death.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Animals; Animals, Newborn; Antigens, CD; Apoptosis; Autophagy; Caspases; Cathepsins; Cell Size; Cell Survival; Cells, Cultured; Cerebellum; Colforsin; Coumarins; Cysteine Proteinase Inhibitors; DNA-Binding Proteins; Dose-Response Relationship, Drug; Drug Interactions; Erythroid-Specific DNA-Binding Factors; Extracellular Signal-Regulated MAP Kinases; Fluorescent Antibody Technique; Gene Expression Regulation; Glycoside Hydrolases; Green Fluorescent Proteins; Lysosomal Membrane Proteins; Lysosomes; Microscopy, Electron; Microtubule Proteins; Neurons; Oligopeptides; Potassium; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Teprotide; Time Factors; Transcription Factors

Autophagic cell death is characterized by the accumulation of vacuoles in physiological and pathological conditions. However, its molecular event is unknown. Here, we show that Atg5, which is known to function in autophagy, contributes to autophagic cell death by interacting with Fas-associated protein with death domain (FADD). Down-regulation of Atg5 expression in HeLa cells suppresses cell death and vacuole formation induced by IFN-gamma. Inversely, ectopic expression of Atg5 using adenoviral delivery induces autophagic cell death. Deletion mapping analysis indicates that procell death activity resides in the middle and C-terminal region of Atg5. Cells harboring the accumulated vacuoles triggered by IFN-gamma or Atg5 expression become dead, and vacuole formation precedes cell death. 3-Methyladenine or expression of Atg5(K130R) mutant blocks both cell death and vacuole formation triggered by IFN-gamma, whereas benzyloxycarbonyl-VAD-fluoromethyl ketone (Z-VAD-fmk) inhibits only cell death but not vacuole formation. Atg5 interacts with FADD via death domain in vitro and in vivo, and the Atg5-mediated cell death, but not vacuole formation, is blocked in FADD-deficient cells. These results suggest that Atg5 plays a crucial role in IFN-gamma-induced autophagic cell death by interacting with FADD.

Topics: Adaptor Proteins, Signal Transducing; Adenine; Amino Acid Chloromethyl Ketones; Autophagy; Autophagy-Related Protein 5; Binding Sites; Cell Death; Cell Line; Fas-Associated Death Domain Protein; Gene Deletion; Gene Expression; HeLa Cells; Humans; Interferon-gamma; Microtubule-Associated Proteins; Mutagenesis; Oligonucleotides, Antisense; Saccharomyces cerevisiae; Transfection; Two-Hybrid System Techniques; Vacuoles

Prostate cancer is one of the most frequently diagnosed cancers in males. Autocrine/paracrine growth factors for the epidermal growth factor receptor (EGFR) have been identified in prostate tumors suggesting a role for EGFR in the progression of prostate cancer. The androgen-dependent prostate cancer cell line, LNCaP, expresses the EGFR as well as two additional members of the family; ErbB-2 and ErbB-3, which can be activated by neuregulin (NRG) isoforms. The effect of ErbB ligands on the viability of LNCaP cells was studied.. In the present study, we examined the effect of NRG on LNCaP cell growth and survival in the absence of androgen mimetic by the MTT assay, FACS analysis, nuclei staining, and Western blotting.. Our results demonstrate that NRG activates ErbB-2/ErbB-3 heterodimers and induces cell death of LNCaP cells. By contrast, EGF activates ErbB-1/ErbB-1 or ErbB-1/ErbB-2 dimers and induces cell growth and survival. Interestingly, LNCaP cells treated with PI3K inhibitor underwent cell death but cells treated with both NRG and PI3K inhibitor survived as the control cells, indicating that the PI3K pathway may mediate NRG-induced cell death. NRG-induced cell death was not inhibited by the broad-spectrum caspases inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK). However, NRG-induced cell death was inhibited by type II cell death inhibitor, 3-methyladenine.. These results suggest that NRG induces type II cell death of LNCaP cells through PI3K-dependent pathway.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Autophagy; Cell Death; Cell Division; Chromones; Cysteine Proteinase Inhibitors; Enzyme Inhibitors; Epidermal Growth Factor; Humans; Ligands; Male; Morpholines; Neuregulins; Phosphorylation; Prostatic Neoplasms; Tumor Cells, Cultured; Tyrosine

Although apoptosis has been considered the typical mechanism for physiological cell death, presently alternative mechanisms need to be considered. We previously showed that fibroblast growth factor-2 (FGF2) could act as a survival factor for neural precursor cells. To study the death mechanism activated by the absence of this growth factor, we followed the changes in cell morphology and determined cell viability by staining with several dyes after FGF2 removal from mesencephalic neural-progenitor-cell cultures. The changes observed did not correspond to those associated with apoptosis. After 48 h in the absence of FGF2, cells began to develop vacuoles in their cytoplasm, a phenotype that became very obvious 3-5 days later. Double-membrane vacuoles containing cell debris were observed. Vacuolated cells did not stain with either ethidium bromide or trypan Blue, and did not show chromatin condensations. Nonetheless, during the course of culture, vacuolated cells formed aggregates with highly condensed chromatin and detached from the plate. Neural progenitor cells grown in the presence of FGF2 did not display any of those characteristics. The vacuolated phenotype could be reversed by the addition of FGF2. Typical autophagy inhibitors such as 3-MA and LY294002 inhibited vacuole development, whereas a broad-spectrum caspase inhibitor did not. Interestingly, Bcl-2 overexpression retarded vacuole development. In conclusion, we identified a death autophagy-like mechanism activated by the lack of a specific survival factor that can be inhibited by Bcl2. We propose that anti-apoptotic Bcl2 family members are key molecules controlling death activation independently of the cell degeneration mechanism used.

Topics: Adenine; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Beclin-1; Caspase Inhibitors; Cell Death; Cell Differentiation; Cell Survival; Chromones; Cycloheximide; Enzyme Inhibitors; Epidermal Growth Factor; Fibroblast Growth Factor 2; Gene Expression Regulation; Glial Fibrillary Acidic Protein; Green Fluorescent Proteins; Immunohistochemistry; Intermediate Filament Proteins; Luminescent Proteins; Mesencephalon; Mice; Microscopy, Electron; Morpholines; Nerve Tissue Proteins; Nestin; Neurons; Proteins; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Stem Cells; Transformation, Genetic; Tubulin; Vacuoles