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Apoptotic Pathway (apoptotic + pathway)
Kinds of Apoptotic Pathway Selected AbstractsThe Protective Effect of Bee Venom against Ethanol-Induced Hepatic Injury via Regulation of the Mitochondria-Related Apoptotic PathwayBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 1 2010Kyung-Hyun Kim Death of hepatocytes is a characteristic feature of chronic liver disease for various causes. Bee venom (Apis mellifera) has been traditionally used for the treatment of various chronic diseases, such as chronic inflammatory arthritis and chronic liver disease. However, the precise mechanism for bee venom in chronic liver disease is not still cleared. To assess the effects of bee venom in chronic liver disease, we investigated the potential role of the bee venom in the ethanol-induced hepatocyte apoptosis. Bee venom treatment inhibited the apoptotic cell morphology and increased the cell viability in ethanol-induced hepatocyte apoptosis. With ethanol treatment, bee venom-treated hepatocytes increased activity of Bcl-2 and Bcl-xL, reduced activity of Bax, Caspase and PARP. In conclusion, bee venom treatment in ethanol-induced hepatocyte apoptosis occurred through the regulation of Bcl family with subsequent inactivation of the Caspase and PARP. These results suggest that bee venom could be an effective agent to reduce ethanol-induced hepatocyte apoptosis. [source] Activation of JNK and PAK2 is essential for citrinin-induced apoptosis in a human osteoblast cell lineENVIRONMENTAL TOXICOLOGY, Issue 4 2009Yu-Ting Huang Abstract The mycotoxin citrinin (CTN), a natural contaminant in foodstuffs and animal feeds, exerts cytotoxic and genotoxic effects on various mammalian cells. CTN causes cell injury, including apoptosis. Previous studies by our group showed that CTN triggers apoptosis in mouse embryonic stem cells, as well as embryonic developmental injury. Here, we investigated the precise mechanisms governing this apoptotic effect in osteoblasts. CTN induced apoptotic biochemical changes in a human osteoblast cell line, including activation of c-Jun N-terminal kinase (JNK), loss of mitochondrial membrane potential, and caspase-3 and p21-activated protein kinase 2 (PAK2) activation. Experiments using a JNK-specific inhibitor, SP600125, and antisense oligonucleotides against JNK reduced CTN-induced activation of both JNK and caspase-3 in osteoblasts, indicating that JNK is required for caspase activation in this apoptotic pathway. Experiments using caspase-3 inhibitors and antisense oligonucleotides against PAK2 revealed that active caspase-3 is essential for PAK2 activation. Moreover, both caspase-3 and PAK2 require activation for CTN-induced apoptosis of osteoblasts. Interestingly, CTN stimulates two-stage activation of JNK in human osteoblasts. Early-stage JNK activation is solely ROS-dependent, whereas late-stage activation is dependent on ROS-mediated caspase activity, and regulated by caspase-induced activation of PAK2. On the basis of these results, we propose a signaling cascade model for CTN-induced apoptosis in human osteoblasts involving ROS, JNK, caspases, and PAK2. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source] A new function for LAT and CD8 during CD8-mediated apoptosis that is independent of TCR signal transductionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2009Raedun L. Clarke Abstract The majority (>95%) of thymocytes undergo apoptosis during selection in the thymus. Several mechanisms have been proposed to explain how apoptosis of thymocytes that are not positively selected occurs; however, it is unknown whether thymocytes die purely by "neglect" or whether signaling through a cell-surface receptor initiates an apoptotic pathway. We have previously demonstrated that on double positive thymocytes the ligation of CD8 in the absence of TCR engagement results in apoptosis and have postulated this is a mechanism to remove thymocytes that have failed positive selection. On mature single positive T cells CD8 acts as a co-receptor to augment signaling through the TCR that is dependent on the phosphorylation of the adaptor protein, linker for activation of T cells (LAT). Here, we show that during CD8-mediated apoptosis of double positive thymocytes there is an increase in the association of CD8 with LAT and an increase in LAT tyrosine phosphorylation. Decreasing LAT expression and mutation of tyrosine residues of LAT reduced apoptosis upon crosslinking of CD8. Our results identify novel functions for both CD8 and LAT that are independent of TCR signal transduction and suggest a mechanism for signal transduction leading to apoptosis upon CD8 crosslinking. [source] Proteasome inhibitor-induced apoptosis in human monocyte-derived dendritic cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 3 2006Alessio Nencioni Dr. Abstract Proteasome inhibitors possess potent antitumor activity against a broad spectrum of human malignancies. However, the effects of these compounds on the immune system still have to be clearly determined. In the present study, we have investigated the effects of proteasome inhibitors on dendritic cells (DC), antigen-presenting cells playing a key role in the initiation of immune responses. Exposure to the proteasome inhibitors bortezomib, MG132 or epoxomicin was found to promote apoptosis of human monocyte-derived DC and to reduce the yield of viable DC when given to monocytes early during differentiation to DC. DC apoptosis via proteasome inhibition was accompanied by mitochondria disruption and subsequent activation of the caspase cascade. Up-regulation and intracellular redistribution of Bcl-2-associated X,protein (Bax), a pro-apoptotic Bcl-2 family protein, were observed in DC treated with these compounds and represent a suitable mechanism leading to activation of the intrinsic apoptotic pathway. Finally, active protein synthesis was found to represent an upstream prerequisite for DC apoptosis induced by proteasome inhibitors, since the translation inhibitor cycloheximide blocked all of the steps of the observed apoptotic response. In conclusion, induction of apoptosis in DC may represent a novel mechanism by which proteasome inhibitors affect the immune response at the antigen-presenting cell level. [source] Maintenance of the relative proportion of oligodendrocytes to axons even in the absence of BAX and BAKEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2009Kumi Kawai Abstract Highly purified oligodendroglial lineage cells from mice lacking functional bax and bak genes were resistant to apoptosis after in-vitro differentiation, indicating an essential role of the intrinsic apoptotic pathway in apoptosis of oligodendrocytes in the absence of neurons (axons) and other glial cells. These mice therefore provide a valuable tool with which to evaluate the significance of the intrinsic apoptotic pathway in regulating the population sizes of oligodendrocytes and oligodendroglial progenitor cells. Quantitative analysis of the optic nerves and the dorsal columns of the spinal cord revealed that the absolute numbers of mature oligodendrocytes immunolabeled for aspartoacylase and adult glial progenitor cells expressing NG2 chondroitin sulfate proteoglycan were increased in both white matter tracts of adult bax/bak -deficient mice and, to a lesser extent, bax -deficient mice, except that there was no increase in NG2-positive progenitor cells in the dorsal columns of these strains of mutant mice. These increases in mature oligodendrocytes and progenitor cells in bax/bak -deficient mice were unexpectedly proportional to increases in numbers of axons in these white matter tracts, thus retaining the oligodendroglial lineage to axon ratios of at most 1.3-fold of the physiological numbers. This is in contrast to the prominent expansion in numbers of neural precursor cells in the subventricular zones of these adult mutant mice. Our study indicates that homeostatic control of cell number is different for progenitors of the oligodendroglial and neuronal lineages. Furthermore, regulatory mechanism(s) operating in addition to apoptotic elimination through the intrinsic pathway, appear to prevent the overproduction of highly mitotic oligodendroglial progenitor cells. [source] Role of Apaf-1, a key regulator of apoptosis, in melanoma progression and chemoresistanceEXPERIMENTAL DERMATOLOGY, Issue 11 2005Mara Campioni Abstract:, Apoptosis protease-activating factor-1 (Apaf-1) is a key regulator of the mitochondrial apoptotic pathway, being the central element of the multimeric apoptosome formed by procaspase 9, cytochrome c, and Apaf-1 itself. In this review, the principal aspects about Apaf-1 gene structure and function, and its role in the apoptotic machinery, are described. Moreover, the most recent findings about the involvement of this molecule in melanoma progression and chemoresistance, as well as the clinico-pathological relevance of these findings in the treatment of this deadly disease, are reported. [source] 3T3-L1 adipocyte apoptosis induced by thiazolidinediones is peroxisome proliferator-activated receptor-,-dependent and mediated by the caspase-3-dependent apoptotic pathwayFEBS JOURNAL, Issue 3 2010Yuanyuan Xiao Although thiazolidinediones (TZDs) are potent promoters of adipogenesis in the preadipocyte, they induce apoptosis in several other cell types, such as cancer cells, endothelial cells and T-lymphocytes. In this study, we investigated the proapoptotic effect of TZDs in mature 3T3-L1 adipocytes, which express high levels of the peroxisome proliferator-activated receptor-, (PPAR,) protein. Apoptosis was induced in mature 3T3-L1 adipocytes by treatment with troglitazone, pioglitazone or prostaglandin J2, and could be blocked by the PPAR, antagonist GW9662. Treatment with PPAR, agonists also decreased Akt-1 protein and phosphorylation levels without affecting phosphoinositide 3-kinase and PTEN. Further analysis indicated that in troglitazone-treated 3T3-L1 adipocytes, Bad phosphorylation and Bcl-2 protein levels were reduced, and Bax translocation to the mitochondria was increased. Subsequently, cytochrome c release and caspase-3 cleavage were observed. TZD-induced adipocyte apoptosis could be blocked by the caspase-3 inhibitor Ac-DEVD-CHO or by overexpression of Bcl2. In cultured rat primary adipocytes, similar apoptosis-inducing effects of troglitazone were also observed. Thus, TZDs promote apoptosis in adipocytes through a PPAR,-dependent pathway. This apoptosis is mediated by the inhibition of Akt-1, which decreases Bad phosphorylation and activates the mitochondrial apoptotic pathway. [source] TBid mediated activation of the mitochondrial death pathway leads to genetic ablation of the lens in Xenopus laevisGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 1 2007D. Du Pasquier Abstract Xenopus is a well proven model for a wide variety of developmental studies, including cell lineage. Cell lineage in Xenopus has largely been addressed by injection of tracer molecules or by micro-dissection elimination of blastomeres. Here we describe a genetic method for cell ablation based on the use of tBid, a direct activator of the mitochondrial apoptotic pathway. In mammalian cells, cross-talk between the main apoptotic pathways (the mitochondrial and the death domain protein pathways) involve the pro-death protein BID, the active form of which, tBID, results from protease truncation and translocation to mitochondria. In transgenic Xenopus, restricting tBID expression to the lens-forming cells enables the specific ablation of the lens without affecting the development of other eye structures. Thus, overexpression of tBid can be used in vivo as a tool to eliminate a defined cell population by apoptosis in a developing organism and to evaluate the degree of autonomy or the inductive effects of a specific tissue during embryonic development. genesis 45:1,10, 2007. © 2006 Wiley-Liss, Inc. [source] Chromodomain helicase/adenosine triphosphatase DNA binding protein 1,like (CHD1l) gene suppresses the nucleus-to-mitochondria translocation of nur77 to sustain hepatocellular carcinoma cell survival,HEPATOLOGY, Issue 1 2009Leilei Chen Amplification of 1q21 has been detected in 58% to 78% of primary hepatocellular carcinoma cases, suggesting that one or more oncogenes within the amplicon play a critical role in the development of this disease. The chromodomain helicase/adenosine triphosphatase DNA binding protein 1,like gene (CHD1L) is a recently identified oncogene localized at 1q21. Our previous studies have demonstrated that CHD1L has strong tumorigenic ability and confers high susceptibility to spontaneous tumors in a CHD1L -transgenic mouse model. In this study, we demonstrate that the antiapoptotic ability of CHD1L is associated with its interaction with Nur77, a critical member of a p53-independent apoptotic pathway. As the first cellular protein identified to bind Nur77, CHD1L is able to inhibit the nucleus-to-mitochondria translocation of Nur77, which is the key step of Nur77-mediated apoptosis, resulting in the hindrance of the release of cytochrome c and the initiation of apoptosis. Knock-down of CHD1L expression by RNA interference could rescue the mitochondrial targeting of Nur77 and the subsequent apoptosis. Further studies found that the C-terminal Macro domain of CHD1L is responsible for the interaction with Nur77, and a CHD1L mutant lacking residues 600-897 failed to interact with Nur77 and prevented Nur77-mediated apoptosis. More importantly, we found that the inhibition of Nur77-mediated apoptosis by endogenous CHD1L is a critical biological cellular process in hepatocarcinogenesis. Conclusion: We demonstrate in this study that overexpression of CHD1L could sustain tumor cell survival by preventing Nur77-mediated apoptosis. (HEPATOLOGY 2009.) [source] Effect of tauroursodeoxycholic acid on endoplasmic reticulum stress,induced caspase-12 activationHEPATOLOGY, Issue 3 2002Qing Xie Activation of death receptors and mitochondrial damage are well-described common apoptotic pathways. Recently, a novel pathway via endoplasmic reticulum (ER) stress has been reported. We assessed the role of tauroursodeoxycholic acid (TUDCA) in inhibition of caspase-12 activation and its effect on calcium homeostasis in an ER stress-induced model of apoptosis. The human liver-derived cell line, Huh7, was treated with thapsigargin (TG) to induce ER stress. Typical morphologic changes of ER stress preceded development of apoptotic changes, including DNA fragmentation and cleavage of poly (adenosine diphosphate-ribose) polymerase (PARP), as well as activation of caspase-3 and -7. Elevation of intracellular calcium levels without loss of mitochondrial membrane potential (MMP) was shown using Fluo-3/Fura-red labeling and flow cytometry, and confirmed by induction of Bip/GRP78, a calcium-dependent chaperon of ER lumen. These changes were accompanied by procaspase-12 processing. TUDCA abolished TG-induced markers of ER stress; reduced calcium efflux, induction of Bip/GRP78, and caspase-12 activation; and subsequently inhibited activation of effector caspases and apoptosis. In conclusion, we propose that mitochondria play a secondary role in ER-mediated apoptosis and that TUDCA prevents apoptosis by blocking a calcium-mediated apoptotic pathway as well as caspase-12 activation. This novel mechanism of TUDCA action suggests new intervention methods for ER stress-induced liver disease. [source] In vivo evaluation of the role of DNp73, protein in regulating the p53-dependent apoptotic pathway after treatment with cytotoxic drugsINTERNATIONAL JOURNAL OF CANCER, Issue 3 2007Maria Antonietta Sabatino Abstract The amino terminus truncated p73 isoform, ,Np73,, shows dominant negative behavior toward TAp73 and wild-type p53, and has oncogenic potential. By contrast, we recently showed that in HCT116 clones forced expression of ,Np73, did not increase in vitro cellular resistance to anticancer agents. The purpose of this study was to characterize in vivo models and to investigate the functional interaction between the ,Np73, isoform and the p53 pathway. Human colon carcinoma HCT116 clones expressing inducible ,Np73, (HCT116/DN3, HCT116/DN14) and HCT116/8a (transfected with the mock empty vector), transplanted in immunodeficient nude mice, were used to study the antitumor activity of cis -diammine-dichloro-platinum (cDDP) (4 mg/kg, i.v., q7d × 3) and Doxorubicin (DX) (7.5 mg/kg, i.v., q7d × 3), with or without tetracycline-induced ,Np73, overexpression. ,Np73, expression was confirmed by RT-PCR, immunoblotting and immunohistochemical analysis. ,Np73, subcellular localization after DX treatment was checked by an immunofluorescence assay. Western blot was used to analyze p53, p21, Bax, Bcl-2 and p53AIP1 expression. ,Np73, overexpression did not modify the antitumor activity of either DX or cDDP in xenograft models. DX reduced ,Np73, protein expression, without affecting its nuclear localization. p53, p21, Bax and p53AIP1 protein expression increased and Bcl-2 decreased in HCT116 clone derived tumors 24 hr after DX exposure, independently of the presence of ,Np73,. Overexpression of ,Np73, does not affect tumor growth in vivo, does not increase the resistance of established tumors to anticancer agents and does not antagonize p53 apoptotic functions. © 2006 Wiley-Liss, Inc. [source] Potential attenuation of p38 signaling by DDB2 as a factor in acquired TNF resistanceINTERNATIONAL JOURNAL OF CANCER, Issue 3 2005Chun-Ling Sun Abstract Our previous study demonstrated that DDB2, a DNA repair protein, attenuates cell surface membrane-associated death signal induced by UV or FasAb; DDB2 is overexpressed in cisplatin-selected cells. However, the molecular mechanism underlying the protective role of DDB2 along the apoptotic pathway remains unknown. Our study identified the cross-resistance of the cisplatin-selected cells to tumor necrosis factor-, (TNF-,). Since knock-down of the DDB2 level rendered cells (HR18) sensitive to the treatment, the cell sensitivity to TNF-, appears inversely proportional to the cellular level of DDB2. Treatment of HeLa cells with TNF-, transiently induced activation of p38MAPK signal, but this induction was significantly reduced in the resistant cells. Overexpression of DDB2 attenuated the activation of p38 in cells. TNF-,-induced apoptotic signals, represented by caspase-8 and downstream substrate cleavage, were reduced in resistant cells compared to their sensitive counterparts. Inhibition of p38 signal by SB202190 clearly attenuated TNF-,-induced apoptotic signals. Moreover, overexpression of DDB2 in HR18 cells also attenuated TNF-, induced caspase activation. These results suggest that p38MAPK activation may be a key upstream signal of TNF-,-induced apoptosis and that attenuation of p38 signal by DDB2 overexpression may be responsible for acquired TNF-, resistance. © 2005 Wiley-Liss, Inc. [source] Heat shock protein 27: its potential role in vascular diseaseINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2006Gordon Ferns Summary Heat shock proteins are molecular chaperones that have an ability to protect proteins from damage induced by environmental factors such as free radicals, heat, ischaemia and toxins, allowing denatured proteins to adopt their native configuration. Heat shock protein-27 (Hsp27) is a member of the small Hsp (sHsp) family of proteins, and has a molecular weight of approximately 27 KDa. In addition to its role as a chaperone, it has also been reported to have many additional functions. These include effects on the apoptotic pathway, cell movement and embryogenesis. In this review, we have focused on its possible role in vascular disease. [source] H2S-induced pancreatic acinar cell apoptosis is mediated via JNK and p38 MAP kinaseJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2008Sharmila Adhikari Abstract Treatment of pancreatic acinar cells by hydrogen sulphide has been shown to induce apoptosis. However, a potential role of mitogen-activated protein kinases (MAPKs) in this apoptotic pathway remains unknown. The present study examined the role of MAPKs in H2S-induced apoptosis in mouse pancreatic acinar cells. Pancreatic acinar cells were treated with 10 ,M NaHS (a donor of H2S) for 3 hrs. For the evaluation of the role of MAPKs, PD98059, SP600125 and SB203580 were used as MAPKs inhibitors for ERK1/2, JNK1/2 and p38 MAPK, respectively. We observed activation of ERK1/2, JNK1/2 and p38 when pancreatic acini were exposed to H2S. Moreover, H2S-induced ERK1/2, JNK1/2 and p38 activation were blocked by pre-treatment with their corresponding inhibitor in a dose-dependent manner. H2S-induced apoptosis led to an increase in caspase 3 activity and this activity was attenuated when caspase 3 inhibitor were used. Also, the cleavage of caspase 3 correlated with that of poly-(ADP-ribose)-polymerase (PARP) cleavage. H2S treatment induced the release of cytochrome c, smac from mitochondria into the cytoplasm, translocation of Bax into mitochondria and decreased the protein level of Bcl-2. Inhibition of ERK1/2 using PD98059 caused further enhancement of apoptosis as evidenced by annexin V staining, while SP600125 and SB203580 abrogated H2S-induced apoptosis. Taken together, the data suggest that activation of ERKs promotes cell survival, whereas activation of JNKs and p38 MAP kinase leads to H2S-induced apoptosis. [source] 2,3,7,8-Tetrachlorodibenzo- p -dioxin modifies expression and nuclear/cytosolic localization of bovine herpesvirus 1 immediate-early protein (bICP0) during infectionJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2010Filomena Fiorito Abstract Our previous studies have demonstrated that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) increases Bovine Herpesvirus 1 (BHV-1) replication through a dose-dependent increase in cytopathy and increased viral titer. Furthermore, TCDD was able to trigger BHV-1-induced apoptosis by up-regulating the activation of initiator caspases 8 and 9, as well as of effector caspase 3. Since TCDD activates caspase 3 after 4,h of infection, we have hypothesized an involvement of BHV-1 infected cell protein 0 (bICP0) in this process. Such protein, the major transcriptional regulatory protein of BHV-1, has been shown to indirectly induce caspase 3 activation and apoptosis. In order to elucidate the role of bICP0 in this apoptotic pathway, here we have analyzed the effects of TCDD on bICP0 expression. Following infection of bovine cells with BHV-1, we detected apoptotic features already at 12,h after infection, only in TCDD exposed groups. Furthermore, in the presence of different doses of TCDD, we observed a time-dependent modulation and increase of bICP0 gene expression levels, as revealed by RT-PCR analysis. Western blot analysis and immunocytochemistry revealed that TCDD induced an increase of bICP0 protein levels in a dose-dependent manner, compared to unexposed groups. Moreover, Western blot analysis of nuclear and cytosolic fractions of infected cells revealed that TCDD anticipated the presence of bICP0 protein in the cytoplasm. In conclusion, both the increase of replication of BHV-1 and anticipation of BHV-1-induced apoptosis could be the result of a relationship between TCDD and bICP0. J. Cell. Biochem. 111: 333,342, 2010. © 2010 Wiley-Liss, Inc. [source] Phosphate regulates embryonic endochondral bone developmentJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2009Alena A. Zalutskaya Abstract Phosphate is required for terminal differentiation of hypertrophic chondrocytes during postnatal growth plate maturation. In vitro models of chondrocyte differentiation demonstrate that 7,mM phosphate, a concentration analogous to that of the late gestational fetus, activates the mitochondrial apoptotic pathway in hypertrophic chondrocytes. This raises the question as to whether extracellular phosphate modulates chondrocyte differentiation and apoptosis during embryonic endochondral bone formation. To address this question, we performed investigations in the mouse metatarsal culture model that recapitulates in vivo bone development. Metatarsals were cultured for 4, 8, and 12 days with 1.25 and 7,mM phosphate. Metatarsals cultured with 7,mM phosphate showed a decrease in proliferation compared to those cultured in 1.25,mM phosphate. This decrease in proliferation was accompanied by an early enhancement in hypertrophic chondrocyte differentiation, associated with an increase in FGF18 expression. By 8 days in culture, an increase caspase-9 activation and apoptosis of hypertrophic chondrocytes was observed in the metatarsals cultured in 7,mM phosphate. Immunohistochemical analyses of embryonic bones demonstrated activation of caspase-9 in hypertrophic chondrocytes, associated with vascular invasion. Thus, these investigations demonstrate that phosphate promotes chondrocyte differentiation during embryonic development and implicate a physiological role for phosphate activation of the mitochondrial apoptotic pathway during embryonic endochondral bone formation. J. Cell. Biochem. 108: 668,674, 2009. © 2009 Wiley-Liss, Inc. [source] Methylene blue-mediated photodynamic therapy induces mitochondria-dependent apoptosis in HeLa CellJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2008Yan Lu Abstract Methylene blue (MB), a widely studied reagent, is investigated in this work for its usage in photodynamic therapy (PDT). PDT has been proved to be highly effective in the treatment of different types of cancers. Previous studies showed MB has both high affinity for mitochondria and high photodynamic efficiency. To elucidate the effects of MB in PDT, we analyzed PDT-induced apoptosis in HeLa cells by introducing different doses of MB into the culture media. Our data showed that MB-mediated PDT triggered intense apoptotic cell death through a series of steps, beginning with photochemical generation of reactive oxygen species. The release of cytochrome c and activation of caspase-3 indicated that MB-PDT-mediated apoptosis in HeLa cells was executed by the mitochondria-dependent apoptotic pathway. Importantly, proteomic studies confirmed that expression levels of several mitochondrial proteins were altered in MB-PDT-induced apoptosis, including TRAP1, mitochondrial elongation factor Tu and peroxiredoxin 3 isoform b. Western blot data showed that phosphorylation of ERK1/2 and PKA were reduced in MB-PDT treated cells, indicating several signal molecules participating in this apoptotic cascade. Moreover, MB-PDT induced an increase in the strength of interaction between Bcl-xL and dephosphorylated Bad. This led to loss of the pro-survival function of Bcl-xL and resulted in mitochondria-mediated apoptosis. This study provides solid evidence of a strong induction by MB-PDT of a mitochondria-dependent apoptosis cascade in HeLa cells. J. Cell. Biochem. 105: 1451,1460, 2008. © 2008 Wiley-Liss, Inc. [source] ARC protects rat cardiomyocytes against oxidative stress through inhibition of caspase-2 mediated mitochondrial pathwayJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2006Yi-Qiang Zhang Abstract Apoptosis repressor with a CARD domain (ARC) has been demonstrated to protect heart cells against ischemia/reperfusion (I/R) injury. In this study, we investigated the mechanism by which ARC protects heart cells against oxidative stress. We monitored the extent of apoptosis and activity of multiple components of the intrinsic apoptotic pathway in rat cardiac myoblast cell line H9c2 with either reduced or increased expression of ARC during oxidative stress. Overexpression of ARC-inhibited oxidative stress-induced caspase-2/3 activation, cytochrome c release, and translocation of Bax to mitochondria. Furthermore, phosphorylation of ARC at threonine 149 was found to be critical to its function. ARC containing a T149A mutation failed to translocate to mitochondria, did not inhibit caspase-2 activation, and had a dominant negative effect against the protective effect of endogenous ARC during oxidative stress. In addition, wild-type ARC but not the T149A mutant inhibited cell death induced by overexpression of caspase-2. Using a yeast two-hybrid (YTH) screening approach and co-immunoprecipitation (Co-IP), we found that protein phosphatase 2C (PP2C) interacted with ARC and that PP2C mediated-dephosphorylation of ARC inhibited its anti-apoptotic activity. Eliminating either the N-terminal CARD domain or the C-terminal P/E domain also abolished the anti-apoptotic function of ARC, suggesting that full-length ARC is required for its apoptotic inhibition. These results indicate that ARC plays an important role in protection of H9c2 cells against oxidative stress-induced apoptosis by phosphorylation-dependent suppression of the mitochondria-mediated intrinsic pathway, partially initiated through the activation of caspase-2. J. Cell. Biochem. 99: 575,588, 2006. © 2006 Wiley-Liss, Inc. [source] Differential control of apoptosis by DJ-1 in prostate benign and cancer cellsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2004Yaacov Hod Abstract DJ-1 is a conserved protein reported to be involved in diverse cellular processes ranging from cellular transformation, control of protein,RNA interaction, oxidative stress response to control of male infertility, among several others. Mutations in the human gene have been shown to be associated with an autosomal recessive, early onset Parkinson's disease (PARK7). The present study examines the control of DJ-1 expression in prostatic benign hyperplasia (BPH-1) and cancer (PC-3) cell lines in which DJ-1 abundance differs significantly. We show that while BPH-1 cells exhibit low basal level of DJ-1 expression, stress-inducing agents such as H2O2 and mitomycin C markedly increase the intracellular level of the polypeptide. In contrast, DJ-1 expression is relatively high in PC-3 cells, and incubation with the same cytotoxic drugs does not modulate further the level of the polypeptide. In correlation with the expression of DJ-1, both cytotoxic agents activate the apoptotic pathway in the prostatic benign cells but not in PC-3 cells, which are resistant to their action. We further demonstrate that incubation of BPH-1 cells with TNF-related-apoptosis-inducing-ligand/Apo-2L (TRAIL) also enhances DJ-1 expression and that TRAIL and H2O2 act additively to stimulate DJ-1 accumulation but synergistically in the activation of the apoptotic pathway. Time-course analysis of DJ-1 stimulation shows that while DJ-1 level increases without significant lag in TRAIL-treated cells, there is a delay in H2O2 -treated cells, and that the increase in DJ-1 abundance precedes the activation of apoptosis. Unexpectedly, over-expression of DJ-1 de-sensitizes BPH-1 cells to the action of apoptotic-inducing agents. However, RNA-interference-mediated silencing of DJ-1 expression results in sensitization of PC-3 cells to TRAIL action. These results are consistent with a model in which DJ-1 is involved in the control of cell death in prostate cell lines. DJ-1 appears to play a differential role between cells expressing a low but inducible level of DJ-1 (e.g., BPH-1 cells) and those expressing a high but constitutive level of the polypeptide (e.g., PC-3 cells). © 2004 Wiley-Liss, Inc. [source] Neuromelanin selectively induces apoptosis in dopaminergic SH-SY5Y cells by deglutathionylation in mitochondria: involvement of the protein and melanin componentJOURNAL OF NEUROCHEMISTRY, Issue 6 2008Makoto Naoi Abstract Parkinson's disease (PD) is characterized by selective depletion of nigral dopamine (DA) neurons containing neuromelanin (NM), suggesting the involvement of NM in the pathogenesis. This study reports induction of apoptosis by NM in SH-SY5Y cells, whereas protease-K-treated NM, synthesized DA- and cysteinyl dopamine melanin showed much less cytotoxicity. Cell death was mediated by mitochondria-mediated apoptotic pathway, namely collapse of mitochondrial membrane potential, release of cytochrome c, and activation of caspase 3, but Bcl-2 over-expression did not suppress apoptosis. NM increased sulfhydryl content in mitochondria, and a major part of it was identified as GSH, whereas dopamine melanin significantly reduced sulfhydryl levels. Western blot analysis for protein-bound GSH demonstrated that only NM reduced S -glutathionylated proteins in mitochondria and dissociated macromolecular structure of complex I. Reactive oxygen and nitrogen species were required for the deglutathionylation by NM, which antioxidants reduced significantly with prevention of apoptosis. These results suggest that NM may be related to cell death of DA neurons in PD and aging through regulation of mitochondrial redox state and S -glutathionylation, for which NM-associated protein is absolutely required. The novel function of NM is discussed in relation to the pathogenesis of PD. [source] PACAP and C2-ceramide generate different AP-1 complexes through a MAP-kinase-dependent pathway: involvement of c-Fos in PACAP-induced Bcl-2 expressionJOURNAL OF NEUROCHEMISTRY, Issue 4 2006Nicolas Aubert Abstract The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) inhibits C2-ceramide-induced cell death through blockade of the mitochondrial apoptotic pathway in rat cerebellar granule neurones. However, the gene induction processes and transcription factors involved in the anti-apoptotic effect of PACAP remain unknown. Here, we show that PACAP and C2-ceramide activate activator protein-1 (AP-1) DNA binding in a dose- and time-dependent manner, but generate different AP-1 dimers. Thus, PACAP increased the proportion of c-Fos and Jun D while C2-ceramide increased c-Jun and reduced c-Fos in AP-1 complexes. In addition, PACAP strongly activated c-Fos gene expression while C2-ceramide markedly increased c-Jun phosphorylation. The effect of PACAP on c-Fos expression was blocked by the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) inhibitor, U0126, while phosphorylation of c-Jun induced by C2-ceramide was abrogated by the protein phosphatase 2A (PP2A) inhibitor, okadaic acid. Transfection of immature granule cells with c-Fos siRNA, which strongly reduced basal and PACAP-stimulated levels of the protein, totally prevented the stimulatory effect of PACAP on Bcl-2 expression. The present study demonstrates that AP-1 complexes containing c-Fos mediate the effect of PACAP on Bcl-2 gene expression in cerebellar granule neurones. Our data also indicate that different AP-1 dimers are associated with the pro-apoptotic effect of C2-ceramide and the anti-apoptotic effect of PACAP. [source] Oxidative stress in the pathogenesis of experimental diabetic neuropathyJOURNAL OF NEUROCHEMISTRY, Issue 2003P. A. Low We evaluated the effects of chronic hyperglycemia on L5 DRG neurons. Experimental diabetic neuropathy (EDN) was induced by streptozotocin. We studied peripheral nerve after 1, 3, 12 months of diabetes. A conduction deficit was present from the first month and persisted over 12 months, affecting mainly sensory fibers. 8-Hydroxy-deoxyguanosine labeling was significantly increased at all time points in DRG neurons, indicating oxidative injury. Caspase-3 labeling was increased at all three time-points, indicating commitment to the efferent limb of the apoptotic pathway. Apoptosis was confirmed by a significant increase in the percent of neurons undergoing apoptosis (TUNEL staining) at 1 month (8%), 3 months (7%) and 12 months (11%). Morphometry of DRG showed a selective loss (42%) of the largest neurons. These findings support the concept that oxidative stress leads to oxidative injury of DRG neurons, with mitochondrium as a specific target, leading to apoptosis and a predominantly sensory neuropathy. [source] Hypoxia-Induced Apoptotic Cell Death is Prevented by Oestradiol Via Oestrogen Receptors in the Developing Central Nervous SystemJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2008V. M. Pozo Devoto The neuroprotective effects of oestrogens have been demonstrated against a variety of insults, including excitotoxicity, oxidative stress and cerebral ischemia under certain conditions. However, the molecular mechanisms underlying oestrogen neuroprotection are still unclear. We aimed to determine whether 17,-oestradiol (E2) administration post-hypoxia (p-hx) was neuroprotective and whether these actions were mediated through oestrogen receptors (ER). For this purpose, 12-embyonic day-old chickens were subjected to acute hypoxia [8% (O2), 60 min], followed by different reoxygenation periods. To test the neuroprotective effect of E2 and its mechanism, embryos were injected 30 min after the end of hypoxia with E2 alone or with ICI 182 780, a competitive antagonist of ER. Cytochrome c (cyt c) release, an indicator of mitochondrial apoptotic pathway, was measured by western blot in optic lobe cytosolic extracts. DNA fragmentation by TUNEL fluorescence and caspase-3 fragmentation by immunofluorescence were detected on optic lobe sections. Acute hypoxia produces a significant increase in cyt c release from mitochondria at 4 h p-hx, followed by an increase in TUNEL positive cells 2 h later (6 h p-hx). Administration of E2 (0.5 mg/egg) produced a significant decrease in cytosolic cyt c levels at 4 h p-hx, in casapse-3 activation and in TUNEL positive cells at 6 h p-hx compared to vehicle treated embryos. In the E2 -ICI 182 780 treated embryos, cyt c release, caspase-3 fragmentation and TUNEL positive cells were similar to the hypoxic embryos, thus suggesting the requirement of an E2,ER interaction for E2 mediated neuroprotective effects. In conclusion, E2 prevents hypoxia-induced cyt c release and posterior cell death and these effects are mediated by oestrogen receptors. [source] The Neuropeptide Pituitary Adenylate Cyclase-Activating Polypeptide Exerts Anti-Apoptotic and Differentiating Effects during Neurogenesis: Focus on Cerebellar Granule Neurones and Embryonic Stem CellsJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2007A. Falluel-Morel Pituitary adenylate cyclase-activating polypeptide (PACAP) was originally isolated from ovine hypothalamus on the basis of its hypophysiotrophic activity. It has subsequently been shown that PACAP and its receptors are widely distributed in the central nervous system of adult mammals, indicating that PACAP may act as a neurotransmitter and/or neuromodulator. It has also been found that PACAP and its receptors are expressed in germinative neuroepithelia, suggesting that PACAP could be involved in neurogenesis. There is now compelling evidence that PACAP exerts neurotrophic activities in the developing cerebellum and in embryonic stem (ES) cells. In particular, the presence of PACAP receptors has been demonstrated in the granule layer of the immature cerebellar cortex, and PACAP has been shown to promote survival, inhibit migration and activate neurite outgrowth of granule cell precursors. In cerebellar neuroblasts, PACAP is a potent inhibitor of the mitochondrial apoptotic pathway through activation of the MAPkinase extracellular regulated kinase. ES cells and embryoid bodies (EB) also express PACAP receptors and PACAP facilitates neuronal orientation and induces the appearance of an electrophysiological activity. Taken together, the anti-apoptotic and pro-differentiating effects of PACAP characterised in cerebellar neuroblasts as well as ES and EB cells indicate that PACAP acts not only as a neurohormone and a neurotransmitter, but also as a growth factor. [source] Expressions of nitrotyrosine and TUNEL immunoreactivities in cultured rat spinal cord neurons after exposure to glutamate, nitric oxide, or peroxynitriteJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2001Y. Manabe Abstract Although excitotoxic and oxidative stress play important roles in spinal neuron death, the exact mechanism is not fully understood. We examined cell damage of primary culture of 11-day-old rat spinal cord by addition of glutamate, nitric oxide (NO) or peroxynitrite (PN) with detection of nitrotyrosine (NT) or terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL). With addition of glutamate, NOC18 (a slow NO releaser) or PN, immunoreactivity for NT became stronger in the cytoplasm of large motor neurons in the ventral horn at 6 to 48 hr and positive in the axons of the ventral horn at 24 to 48 hr. TUNEL positive nuclei were found in spinal large motor neurons from 24 hr, and the positive cell number greatly increased at 48 hr in contrast to the vehicle. Pretreatment of cultures with ,-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate receptor antagonist, NO-suppressing agent, and antioxidant protected the immunoreactivity for NT or TUNEL. The present results suggest that both excitotoxic and oxidative stress play an important role in the upregulation of NT nitration and the apoptotic pathway in cultured rat spinal neurons. J. Neurosci. Res. 65:371,377, 2001. © 2001 Wiley-Liss, Inc. [source] The ,670A > G polymorphism in the promoter region of the FAS gene is associated with necrosis in periportal areas in patients with chronic hepatitis CJOURNAL OF VIRAL HEPATITIS, Issue 6 2005J. Aguilar-Reina Summary., Evidence suggests that apoptosis of liver cells may play a significant role in the pathogenesis of hepatitis C virus (HCV) infection. One of the best characterized apoptotic pathway is that mediated by the death receptor Fas. Fas expression has been found to be up-regulated on hepatocytes in chronic HCV infection, particularly in periportal areas. Recently, two polymorphisms have been identified in the promotor region of the FAS gene, ,1377G > A and ,670A > G. We have evaluated the involvement of these variants in the susceptibility to HCV infection, the severity of liver damage and progression of fibrosis in chronic hepatitis C. A cohort of 197 patients with chronic hepatitis C and 100 controls were analysed for both polymorphisms by Fluorescence Resonance Energy Transfer using specific probes and the LightcyclerTM system. In addition, liver biopsies were taken in 167 patients and scored using the Knodell classification system. We have found that the allele frequencies and the distribution of both polymorphisms do not differ significantly in the HCV cohort and in the control population. Thus, none of the polymorphisms seems to be related with susceptibility to HCV infection. However, we have examined the possible association between the two variants and the grade of necroinflammatory activity and the stage of fibrosis and we have detected an under-representation of the ,670A > G variant among those patients with higher Knodell's scores (P = 0.049) and necroinflammatory activity (P = 0.036). The ,670A allele was associated with higher levels of periportal necrosis (P = 0.012). In conclusion, our findings suggest an association between the ,670A > G polymorphism and the grade of necrosis in periportal areas in patients with chronic hepatitis C. [source] Polyporenic acid C induces caspase-8-mediated apoptosis in human lung cancer A549 cellsMOLECULAR CARCINOGENESIS, Issue 6 2009Hui Ling Abstract Lung cancer continues to be the leading cause of cancer-related mortality worldwide. This warrants the search for new and effective agents against lung cancer. We and others have recently shown that lanostane-type triterpenoids isolated from the fungal species Poria cocos (P. cocos) can inhibit cancer growth. However, the mechanisms responsible for the anticancer effects of these triterpenoids remain unclear. In this study, we investigated the effect of polyporenic acid C (PPAC), a lanostane-type triterpenoid from P. cocos, on the growth of A549 nonsmall cell lung cancer cells (NSCLC). The results demonstrate that PPAC significantly reduced cell proliferation via induction of apoptosis as evidenced by sub-G1 analysis, annexin V-FITC staining, and increase in cleavage of procaspase-8, -3, and poly(ADP-ribose)-polymerase (PARP). However, unlike our previously reported lanostane-type triterpenoid, pachymic acid, treatment of cells with PPAC was not accompanied by disruption of mitochondrial membrane potential and increase in cleavage of procaspase-9. Further, PPC-induced apoptosis was inhibited by caspase-8 and pan caspase inhibitors but not by a caspase-9 inhibitor. Taken together, the results suggest that PPAC induces apoptosis through the death receptor-mediated apoptotic pathway where the activation of caspase-8 leads to the direct cleavage of execution caspases without the involvement of the mitochondria. Furthermore, suppressed PI3-kinase/Akt signal pathway and enhanced p53 activation after PPAC treatment suggests this to be an additional mechanism for apoptosis induction. Together, these results encourage further studies of PPAC as a promising candidate for lung cancer therapy. © 2008 Wiley-Liss, Inc. [source] 6-Dehydrogingerdione, an active constituent of dietary ginger, induces cell cycle arrest and apoptosis through reactive oxygen species/c-Jun N-terminal kinase pathways in human breast cancer cellsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 9 2010Ya-Ling Hsu Abstract This study is the first to investigate the anticancer effect of 6-dehydrogingerdione (DGE), an active constituent of dietary ginger, in human breast cancer MDA-MB-231 and MCF-7 cells. DGE exhibited effective cell growth inhibition by inducing cancer cells to undergo G2/M phase arrest and apoptosis. Blockade of cell cycle was associated with increased levels of p21, and reduced amounts of cyclin B1, cyclin A, Cdc2 and Cdc25C. DGE also enhanced the levels of inactivated phosphorylated Cdc2 and Cdc25C. DGE triggered the mitochondrial apoptotic pathway indicated by a change in Bax/Bcl-2 ratios, resulting in caspase-9 activation. We also found the generation of reactive oxygen species is a critical mediator in DGE-induced cell growth inhibition. DGE clearly increased the activation of apoptosis signal-regulating kinase 1 and c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase 1/2 (ERK1/2) and p38. In addition, antioxidants vitamin C and catalase significantly decreased DGE-mediated JNK activation and apoptosis. Moreover, blocking JNK by specific inhibitors suppressed DGE-triggered mitochondrial apoptotic pathway. Taken together, these findings suggest that a critical role for reactive oxygen species and JNK in DGE-mediated apoptosis of human breast cancer. [source] Actinobacillus actinomycetemcomitans induces apoptosis of T lymphocytes by the Fas and Fas ligand pathwayMOLECULAR ORAL MICROBIOLOGY, Issue 5 2002A. Nalbant Actinobacillus actinomycetemcomitans expresses a number of toxins capable of inducing apoptotic cell death of T lymphocytes. However, the exact mechanism(s) has not been elucidated. The present study investigated the involvement of the Fas (CD95)-mediated apoptotic pathway in A. actinomycetemcomitans -induced T-cell apoptosis. To that end, peripheral blood mononuclear cells (PBMC) were cultured with or without A. actinomycetemcomitans cell-free culture supernatant (CFCS) for 0,96 h. The cells were then labeled with specific monoclonal antibodies and flow cytometry was performed. Results demonstrated up-regulation of Fas and activation of caspase-3 in T cells in response to A. actinomycetemcomitans CFCS. Monocytes were the only cells analyzed to express Fas ligand (FasL) constitutively, and this was further up-regulated in response to A. actinomycetemcomitans CFCS, while T cells expressed FasL only after this stimulation. Depletion of monocytes prior to stimulation with A. actinomycetemcomitans CFCS led to a marked decline in apoptosis. Blocking of Fas,FasL interactions with anti-Fas monoclonal antibody or Fas:Fc fusion protein lead to a significant decline, but not abolition, of T-cell apoptosis. Nearly all T cells expressed Bcl-2 at the outset of culture, and Bcl-2 expression declined in T cells stimulated with A. actinomycetemcomitans CFCS. Collectively, these data provide evidence for the induction of T-cell apoptosis by A. actinomycetemcomitans via the Fas-mediated pathway, involving caspase-3 and Bcl- 2. Moreover, this apoptotic response was dependent on the presence of monocytes. [source] Characterization of the caspase cascade in a cell culture model of SOD1-related familial amyotrophic lateral sclerosis: expression, activation and therapeutic effects of inhibitionNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 5 2005S. Sathasivam There is increasing evidence that apoptosis or a similar programmed cell death pathway is the mechanism of cell death responsible for motor neurone degeneration in amyotrophic lateral sclerosis. Knowledge of the relative importance of different caspases in the cell death process is at present incomplete. In addition, there is little information on the critical point of the death pathway when the process of dying becomes irreversible. In this study, using the well-established NSC34 motor neurone-like cell line stably transfected with empty vector, normal or mutant human Cu-Zn superoxide dismutase (SOD1), we have characterized the activation of the caspase cascade in detail, revealing that the activation of caspases-9, -3 and -8 are important in motor neurone death and that the presence of mutant SOD1 causes increased activation of components of the apoptotic cascade under both basal culture conditions and following oxidative stress induced by serum withdrawal. Activation of the caspases identified in the cellular model has been confirmed in the G93A SOD1 transgenic mice. Furthermore, investigation of the effects of anti-apoptotic neuroprotective agents including specific caspase inhibitors, minocycline and nifedipine, have supported the importance of the mitochondrion-dependent apoptotic pathway in the death process and revealed that the upstream caspase cascade needs to be inhibited if useful neuro-protection is to be achieved. [source] | ||||||||||||||||||||||||||||||||||||||||