Peroxynitrite is a highly reactive nitrogen species and a potent inducer of apoptosis and necrosis in somatic cells. Peroxynitrite-induced nitrosative stress has emerged as a major cause of impaired sperm function; however, its ability to trigger cell death has not been described in human spermatozoa. The objective here was to characterize biochemical and morphological features of cell death induced by peroxynitrite-mediated nitrosative stress in human spermatozoa. For this, spermatozoa were incubated with and without (untreated control) 3-morpholinosydnonimine (SIN-1), in order to generate peroxynitrite. Sperm viability, mitochondrial permeability transition (MPT), externalization of phosphatidylserine, DNA oxidation and fragmentation, caspase activation, tyrosine nitration, and sperm ultrastructure were analyzed. The results showed that at 24 h of incubation with SIN-1, the sperm viability was significantly reduced compared to untreated control (P < 0.001). Furthermore, the MPT was induced (P < 0.01) and increment in DNA oxidation (P < 0.01), DNA fragmentation (P < 0.01), tyrosine nitration (P < 0.0001) and ultrastructural damage were observed when compared to untreated control. Caspase activation was not evidenced, and although phosphatidylserine externalization increased compared to untreated control (P < 0.001), this process was observed in <10% of the cells and the gradual loss of viability was not characterized by an important increase in this parameter. In conclusion, peroxynitrite-mediated nitrosative stress induces the regulated variant of cell death known as MPT-driven necrosis in human spermatozoa. This study provides a new insight into the pathophysiology of nitrosative stress in human spermatozoa and opens up a new focus for developing specific therapeutic strategies to better preserve sperm viability or to avoid cell death.
Adult ; Caspases/metabolism* ; Cell Death ; Enzyme Activation ; Humans ; Male ; Mitochondria/pathology* ; Necrosis ; Nitrosative Stress/physiology* ; Permeability ; Peroxynitrous Acid/pharmacology* ; Phosphatidylserines/metabolism* ; Spermatozoa/ultrastructure*

Transient receptor potential (TRP) channel is a superfamily of cation channels located on the cell membrane. TRP channels are classified into seven subfamilies based on the amino acid sequence homology,and transient receptor potential melastatin 2(TRPM2) is the second member of the TRPM subfamily. More evidences have revealed the important roles of TRPM2 in physiological and pathological events such as release of insulin from pancreatic Β-cells,inflammatory cytokines production from cells,and oxidative stress-induced cell death. As a cellular sensor for oxidative stress channel,TRPM2 is activated by a variety of factors. TRPM2 is a potential therapeutic target for oxidative stress-related diseases.
Cell Death ; Cytokines ; Humans ; Insulin ; Oxidative Stress ; TRPM Cation Channels ; physiology

Entamoeba histolytica is a tissue-invasive protozoan parasite causing dysentery in humans. During infection of colonic tissues, amoebic trophozoites are able to kill host cells via apoptosis or necrosis, both of which trigger IL-8-mediated acute inflammatory responses. However, the signaling pathways involved in host cell death induced by E. histolytica have not yet been fully defined. In this study, we examined whether calpain plays a role in the cleavage of pro-survival transcription factors during cell death of colonic epithelial cells, induced by live E. histolytica trophozoites. Incubation with amoebic trophozoites induced activation of m-calpain in a time- and dose-dependent manner. Moreover, incubation with amoebae resulted in marked degradation of STAT proteins (STAT3 and STAT5) and NF-kappaB (p65) in Caco-2 cells. However, IkappaB, an inhibitor of NF-kappaB, was not cleaved in Caco-2 cells following adherence of E. histolytica. Entamoeba-induced cleavage of STAT proteins and NF-kappaB was partially inhibited by pretreatment of cells with a cell-permeable calpain inhibitor, calpeptin. In contrast, E. histolytica did not induce cleavage of caspase-3 in Caco-2 cells. Furthermore, pretreatment of Caco-2 cells with a calpain inhibitor, calpeptin (but not the pan-caspase inhibitor, z-VAD-fmk) or m-calpain siRNA partially reduced Entamoeba-induced DNA fragmentation in Caco-2 cells. These results suggest that calpain plays an important role in E. histolytica-induced degradation of NF-kappaB and STATs in colonic epithelial cells, which ultimately accelerates cell death.
Caco-2 Cells ; Calcium-Binding Proteins ; Calpain/genetics/metabolism ; Caspase 3/genetics/metabolism ; Caspases ; *Cell Death ; Colon/cytology ; Entamoeba histolytica/*physiology ; Epithelial Cells/cytology/parasitology ; Humans ; I-kappa B Proteins/metabolism ; Intestinal Mucosa/cytology ; NF-kappa B/genetics/*metabolism ; RNA Interference ; RNA, Small Interfering ; STAT3 Transcription Factor/genetics/*metabolism ; STAT5 Transcription Factor/genetics/*metabolism ; Signal Transduction

Erythrocytes lack nuclei and mitochondria, critical elements in the machinery of nucleated cell apoptosis. However, most recently, it became obvious that erythrocytes may undergo programmed aging, as well as suicidal death. The term eryptosis has been coined to describe the suicidal erythrocyte death. Eryptosis is triggered mainly by increased cytosolic Ca(2+) activity, in turn, Ca(2+) activates Ca(2+)-sensitive K(+) channels, scramblase, calpain and other proteases, respectively. A series of molecular events of erythrocyte programmed death induced. The cascade reaction of related molecules and finally lead to cell clearance. There is evidence suggesting that erythrocytes aging and death process are regulated tightly and there are many molecular participants and signaling pathways involved in aging and death process of erythrocytes. Erythrocytes have already been used as a model for aging study, and the knowledge about mechanisms involved in eryptosis may provide an important clue to understand the mechanisms involved in suicidal death of nucleated cells. In this review the factors influencing programmed death of erythrocytes, the role of Ca(2+) and ceramide in programmed death of erythrocytes, the role of blebbing in process of erythrocyte aging, the antigens of erythrocyte aging and so on are summarized.
Calcium ; physiology ; Cell Death ; Cellular Senescence ; Ceramides ; physiology ; Erythrocytes ; cytology ; Humans

Cell death and survival are tightly controlled through the highly coordinated activation/inhibition of diverse signal transduction pathways to insure normal development and physiology. Imbalance between cell death and survival often leads to autoimmune diseases and cancer. Death receptors sense extracellular signals to induce caspase-mediated apoptosis. Acting upstream of CED-3 family proteases, such as caspase-3, Bcl-2 prevents apoptosis. Using short hairpin RNAs (shRNAs), we suppressed Bcl-2 expression in Jurkat T cells, and this increased TCR-triggered AICD and enhanced TNFR gene expression. Also, knockdown of Bcl-2 in Jurkat T cells suppressed the gene expression of FLIP, TNF receptor-associated factors 3 (TRAF3) and TRAF4. Furthermore, suppressed Bcl-2 expression increased caspase-3 and diminished nuclear factor kappa B (NF-kappaB) translocation.
Apoptosis ; Autoimmune Diseases ; Caspase 3 ; Cell Death* ; Gene Expression ; Humans ; NF-kappa B ; Peptide Hydrolases ; Physiology ; Receptors, Death Domain ; RNA, Small Interfering ; Signal Transduction ; T-Lymphocytes* ; TNF Receptor-Associated Factor 4 ; Tumor Necrosis Factor Receptor-Associated Peptides and Proteins

Entamoeba histolytica, which causes amoebic colitis and occasionally liver abscess in humans, is able to induce host cell death. However, signaling mechanisms of colon cell death induced by E. histolytica are not fully elucidated. In this study, we investigated the signaling role of NOX in cell death of HT29 colonic epithelial cells induced by E. histolytica. Incubation of HT29 cells with amoebic trophozoites resulted in DNA fragmentation that is a hallmark of apoptotic cell death. In addition, E. histolytica generate intracellular reactive oxygen species (ROS) in a contact-dependent manner. Inhibition of intracellular ROS level with treatment with DPI, an inhibitor of NADPH oxidases (NOXs), decreased Entamoeba-induced ROS generation and cell death in HT29 cells. However, pan-caspase inhibitor did not affect E. histolytica-induced HT29 cell death. In HT29 cells, catalytic subunit NOX1 and regulatory subunit Rac1 for NOX1 activation were highly expressed. We next investigated whether NADPH oxidase 1 (NOX1)-derived ROS is closely associated with HT29 cell death induced by E. histolytica. Suppression of Rac1 by siRNA significantly inhibited Entamoeba-induced cell death. Moreover, knockdown of NOX1 by siRNA, effectively inhibited E. histolytica-triggered DNA fragmentation in HT29 cells. These results suggest that NOX1-derived ROS is required for apoptotic cell death in HT29 colon epithelial cells induced by E. histolytica.
*Cell Death ; Cell Line ; Entamoeba histolytica/*pathogenicity ; Epithelial Cells/metabolism/*parasitology/*physiology ; *Host-Pathogen Interactions ; Humans ; NADPH Oxidase/*metabolism ; Reactive Oxygen Species/metabolism/*toxicity ; Signal Transduction

Acute and chronic neurodegenerative diseases are illnesses associated with high morbidity and mortality, and few or no effective options are available for their treatments. Many neurodegenerative diseases are included in them, for example, stroke, brain trauma, spinal cord injury, amyotrophic lateral sclerosis (ALS), Huntington's disease, Alzheimer's disease, and Parkinson's disease. Given that central nervous system tissue has very limited, if any, regenerative capacity, it is of utmost importance to limit the damage caused by neuronal death. During the past decade, considerable progress has been made in understanding the process of cell death. In this article, we review the causes and mechanisms of neuronal-cell death, especially as it pertains to the caspases family of proteases associated with cell death. The results may be helpful to the experimental research and clinical application of neurodegenerative diseases.
Animals ; Apoptosis ; physiology ; Caspases ; metabolism ; Cell Death ; Humans ; Neurodegenerative Diseases ; enzymology ; pathology ; Neurons ; pathology ; Peptide Hydrolases ; metabolism

OBJECTIVETo investigate the regulation of different hypoxia on cell survival and autophagy.

METHODSPC12 cells were treated with different hypoxia. The cell survival was measured by MTT assay, expressions of LC3 and p62 were marked for autophagy detected by Western Blot, and the level of reactive oxygen species (ROS) was analyzed by flow cytometry.

RESULTSThe cell viability was different under different hypoxia: moderate hypoxia promoted cell viability, and severe hypoxia caused a decrease in cell viability; autophagy marker molecules, p62 and LC3-II expressions were different: moderate hypoxia increased p62 and LC3-II expressions, in contrast, severe hypoxia led to the decrease of p62 and LC3-II expressions; compared to normoxia, moderate hypoxia did not change the levels of ROS, while severe hypoxia increased the levels; 3-MA, the inhibitor of autophagy, elevated the levels of ROS in the three oxygen concentrations, additionally, the increased amplitudes in the moderate and severe hypoxia groups were higher than that in the normoxia group.

CONCLUSIONModerate hypoxia promotes cell survival, severe hypoxia causes the cell death, and the autophagy activity may mediate the effects of different hypoxia.

Animals ; Autophagy ; physiology ; Cell Death ; Cell Hypoxia ; Cell Survival ; PC12 Cells ; Rats ; Reactive Oxygen Species ; metabolism

Spinal cord injury (SCI) is frequently companied by necrosis and apoptosis of oligodendrocytes (OLs), which contributes to demyelination of myelinated nerve fibers and their electrophysiological defects. This pathological demyelination often results in sensory or motor deficits. Here, we first focus on the microenvironment changes after SCI that cause OLs' death, then discuss the major mechanism of endogenous oligodendrocytogenesis and axonal remyelination, and finally summarize current therapies targeting OLs protection and replacement.
Animals ; Apoptosis ; physiology ; Cell Death ; physiology ; Humans ; Necrosis ; pathology ; Nerve Fibers, Myelinated ; pathology ; Nerve Regeneration ; physiology ; Oligodendroglia ; pathology ; Spinal Cord ; physiopathology ; Spinal Cord Injuries ; pathology ; physiopathology ; therapy

This study is to investigate the effects of indirubin on ATP-induced immune responses of macrophages. For this, neutral red dye uptake method was used to test phagocytosis, MTT assay was used for measuring cell death, and reactive oxygen species (ROS) was tested with fluorescent probe DHE. The data showed that extracellular ATP attenuated phagocytosis, induced cell death and increased ROS production, and these effects were restored by pre-treating with indirubin. This result suggested that indirubin blockade the effects of ATP on macrophages, because extracellular ATP-induced effects are dependent on P2 receptors, in particular P2X7 receptors. Furthermore, the effects of indirubin on the activation of P2 receptors were tested, in particular P2X7 receptors. The data showed that indirubin significantly decreased ATP-induced, P2 receptors mediated intracellular Ca2+ concentration ([Ca2+]i) rise and inhibited P2X7 receptor-based ethidium bromide (EB) dye uptake. These results suggested the inhibitory effects of indirubin on the activation of P2X7 receptors, which may underlying the effects on ATP induced ROS production, phagocytosis attenuation and cell death of macrophages.
Adenosine Triphosphate ; pharmacology ; Animals ; Calcium ; metabolism ; Cell Death ; drug effects ; Indoles ; pharmacology ; Macrophages ; cytology ; metabolism ; physiology ; Male ; Phagocytosis ; drug effects ; Rats ; Rats, Wistar ; Reactive Oxygen Species ; metabolism ; Receptors, Purinergic P2X7 ; metabolism