Home About us Contact
|
Home About us Contact | ||
|
|
||
Death Signals (death + signal)
Selected AbstractsLevamisole induced apoptosis in cultured vascular endothelial cellsBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2000Michaela Artwohl To better understand the anticancer activity of Levamisole (LMS), which serves as an adjuvant in colon cancer therapy in combination with 5-Fluorouracil, this study analyses LMS' ability to induce apoptosis and growth arrest in cultured human micro- and macrovascular endothelial cells (ECs) and fibroblasts. Cells exposed (24 h) to Levamisole (range: 0.5,2 mmol l,1) alone or in combination with antioxidants (10 mmol l,1 glutathione or 5 mmol l,1 N-Acetylcysteine or 0.1 mmol l,1 Tocopherol) were evaluated for apoptosis (3H-thymidine assays, in situ staining), mRNA/protein expression (Northern/Western blot), and proliferation (3H-thymidine incorporation). Levamisole dose-dependently increased apoptosis in ECs to 230% (HUVECs-human umbilical vein ECs), 525% (adult human venous ECs) and 600% (human uterine microvascular ECs) but not in fibroblasts compared to control cells (set as 100%). Levamisole increased in ECs integrin-dependent matrix adhesion, inhibited proliferation (,70%), reduced expression of survival factors such as clusterin (,30%), endothelin-1 (,43%), bcl-2 (,34%), endothelial NO-synthase (,32%) and pRb (Retinoblastoma protein: ,89%), and increased that of growth arrest/death signals such as p21 (+73%) and bak (+50%). LMS (2 mmol l,1)-induced apoptosis was inhibited by glutathione (,50%) and N-Acetylcysteine (,36%), which also counteracted reduction by Levamisole of pRb expression, suggesting reactive oxygen species and pRb play a role in these processes. The ability of LMS to selectively induce apoptosis and growth arrest in endothelial cells potentially hints at vascular targeting to contribute to Levamisole's anticancer activity. British Journal of Pharmacology (2000) 131, 1577,1583; doi:10.1038/sj.bjp.0703660 [source] The resident endoplasmic reticulum protein, BAP31, associates with ,-actin and myosin B heavy chainFEBS JOURNAL, Issue 2 2003Analysis by capillary liquid chromatography microelectrospray tandem MS BAP31 is a 28-kDa integral membrane protein of the endoplasmic reticulum whose cytosolic domain contains two caspase recognition sites that are preferentially cleaved by initiator caspases, such as caspase-8. Recently, we reported that the caspase-resistant BAP31 inhibited Fas-mediated apoptotic membrane fragmentation and the release of cytochrome c from mitochondria in KB epithelial cells (Nguyen M., Breckenridge G., Ducret A & Shore G. (2000) Mol. Cell. Biol.20, 6731,6740). We describe here the characterization by capillary liquid chromatography microelectrospray tandem MS of a BAP31 immunocomplex isolated from a HepG2 cell lysate in the absence of a death signal. We show that BAP31 specifically associates with nonmuscle myosin heavy chain B and nonmuscle ,-actin, two components of the cytoskeleton actomyosin complex. Collectively, these data confirm that BAP31, in addition to its potential role as a chaperone, may play a fundamental role in the structural organization of the cytoplasm. Here we also show that Fas stimulation of apoptosis releases BAP31 associations with these motor proteins, a step that may contribute to extranuclear events, such as membrane remodelling, during the execution phase of apoptosis. [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] Alternatively spliced transcripts of Fas mRNAs in feline lymphoid cellsINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 4 2004T. Mizuno Summary Fas belongs to the tumour necrosis factor receptor family and transduces the death signal after binding to the Fas ligand. Five feline lymphoma cell lines were shown, by reverse transcription,polymerase chain reaction, to express six species of Fas transcripts. Based on sequence comparison of these Fas transcripts with the genomic Fas gene, five of the six transcripts were found to be generated through alternative splicing and to encode five different Fas proteins lacking the transmembrane domain. We also detected such alternatively spliced transcripts in primary tumour tissues from cats with naturally occurring lymphoma. These results suggest a possible association of the alternatively spliced Fas variants with the pathogenesis of feline lymphoma. [source] Matrix Regulation of Skeletal Cell Apoptosis II: Role of Arg-Gly-Asp-Containing PeptidesJOURNAL OF BONE AND MINERAL RESEARCH, Issue 1 2002Robert L. Perlot Jr. Abstract This investigation was based on the assumption that arg-gly-asp (RGD)-containing peptides are released from the extracellular matrix of bone and cartilage during the remodeling cycle. We asked the question: Can RGD peptides influence skeletal cell viability? Primary human osteoblasts, mouse MC-3T3-E1 cells, and chick chondrocytes were incubated with purified RGD-containing peptides and cell viability was determined. The RGD peptide did not kill osteoblasts, chondrocytes, or MC-3T3-E1 cells. In contrast, RGDS and GRGDSP peptides killed all three cell types. Osteoblast death was quite rapid, occurring within 6 h of treatment. transferase uridyl mediated nick end labeling (TUNEL) and transmission electron microscopy (TEM) analysis indicated that death was mediated by apoptosis. To learn if mitochondria transduced the death signal, cells were treated with RGDS and organelle function was evaluated using a voltage-sensitive fluorescent probe. It was observed that there was no net loss of fluorescence and, hence, it was concluded that mitochondria were not the primary effectors of the apoptotic response. Experiments were performed with enzyme inhibitors to determine the import of the caspase pathway on RGDS-mediated osteoblast apoptosis. Results of these studies, as well as a study conducted using a fluorescent substrate, pointed to caspase 3 mediating the effector stage of the apoptotic process. Finally, using a purified labeled-RGDS peptide, we showed that the molecule was not restricted by the plasma membrane because it was accumulated in the cytosolic compartment. Results of the investigation support the view that resorption of the extracellular matrix generates peptide products that can induce apoptosis of vicinal cells. [source] Diazepam Promotes ATP Recovery and Prevents Cytochrome c Release in Hippocampal Slices After In Vitro IschemiaJOURNAL OF NEUROCHEMISTRY, Issue 3 2000Francesca Galeffi Abstract: Benzodiazepines protect hippocampal neurons when administered within the first few hours after transient cerebral ischemia. Here, we examined the ability of diazepam to prevent early signals of cell injury (before cell death) after in vitro ischemia. Ischemia in vitro or in vivo causes a rapid depletion of ATP and the generation of cell death signals, such as the release of cytochrome c from mitochondria. Hippocampal slices from adult rats were subjected to 7 min of oxygen-glucose deprivation (OGD) and assessed histologically 3 h after reoxygenation. At this time, area CA1 neurons appeared viable, although slight abnormalities in structure were evident. Immediately following OGD, ATP levels in hippocampus were decreased by 70%, and they recovered partially over the next 3 h of reoxygenation. When diazepam was included in the reoxygenation buffer, ATP levels recovered completely by 3 h after OGD. The effects of diazepam were blocked by picrotoxin, indicating that the protection was mediated by an influx of Cl - through the GABAA receptor. It is interesting that the benzodiazepine antagonist flumazenil did not prevent the action of diazepam, as has been shown in other studies using the hippocampus. Two hours after OGD, the partial recovery of ATP levels occurred simultaneously with an increase of cytochrome c (,400%) in the cytosol. When diazepam was included in the reoxygenation buffer, it completely prevented the increase in cytosolic cytochrome c. Thus, complete recovery of ATP and prevention of cytochrome c release from mitochondria can be achieved when diazepam is given after the loss of ATP induced by OGD. [source] Novel initiation genes in squamous cell carcinomagenesis: A role for substrate-specific ubiquitylation in the control of cell survivalMOLECULAR CARCINOGENESIS, Issue 8 2007Amador Albor Abstract The study of experimental epidermal carcinogenesis offers several advantages over other epithelial carcinogenesis models, including easy accessibility and a database of research findings spanning over a century. Our studies make use of a clonal in vitro/in vivo keratinocyte carcinogenesis model with low frequency of ras mutation and derivative clonal-initiated lineages with distinct tumor fate. Analysis of this model has yielded candidate genes involved in the stages of initiation and tumorigenic progression, and has revealed novel roles for ubiquitylation in transcriptional control of survival and apoptotic pathways during the early stages of carcinogenesis. The expression of a recently described E3-ubiquitin ligase, Trim32, is elevated during initiation, and ectopic expression of Trim32 confers extended survival in response to terminal differentiation and ultraviolet light (UV) B/TNF-, death signals. Trim32 binds and ubiquitylates Piasy, controlling its stability and accumulation. Piasy is a SUMOylation factor involved in the control of apoptosis, senescence, and NF-,B activation. NF-,B is a survival factor for keratinocytes in response to UV irradiation, the main carcinogenic stimulus for the epidermis. Piasy inhibits NF-,B activity, and promotes keratinocyte apoptosis in response to UV and TNF-,. In human skin squamous cell carcinoma (SCC) samples, we found an inverse correlation between Trim32 and Piasy expression supporting a role for Trim32,Piasy interaction in human epidermal carcinogenesis. Our hypothesis is that increased expression of Trim32 may enhance epidermal carcinogenesis, by increasing the threshold of NF-,B activity through Piasy downmodulation. © 2007 Wiley-Liss, Inc. [source] BH4 peptide derived from Bcl-xL and Bax-inhibitor peptide suppresses apoptotic mitochondrial changes in heat stressed bovine oocytesMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 7 2009Paolete Soto Mitochondria play an important role in the integration and transmission of cell death signals mediated by the Bcl-2 family proteins. Experiments were conducted to determine whether the anti-apoptotic peptides BH4 domain of Bcl-xL (TAT-BH4) and Bax inhibitor peptide (BIP) suppresses heat stress (HS) injury in oocytes by reduction of apoptotic-like events. Cumulus,oocyte complexes (COCs) were matured at 39°C (control) or 41°C (HS) for 21 hr then placed in maturation medium containing 0 or 100 µM BIP in water and 0 or 1 µM TAT-BH4 in dimethyl sulfoxide (DMSO), or a combination of both peptides (BIP,+,BH4). Peptide effects on embryo development, DNA fragmentation, mitochondrial membrane potential (,,m), and mitochondrial DNA (mtDNA) copy number were measured. All groups were fertilized and cultured in vitro at 39°C for 8 days. Compared to control, HS-treated oocytes induced a decrease in embryo development (P,<,0.05), increase in proportion of TUNEL-positive chromatin in oocytes and blastocysts (P,<,0.05), and loss of oocyte ,,m (P,<,0.001). In the presence of BIP or BIP,+,BH4, development of HS-treated oocytes into blastocysts was increased (P,<,0.05). Conversely, COCs matured with TAT-BH4 at 41°C showed reduced embryonic development (P,<,0.05). Exposure of HS-treated to each or both peptides resulted in a reduction of TUNEL frequency in oocytes and blastocysts cells derived from these oocytes (P,<,0.05). The loss of ,,m in HS-treated oocytes was not restored by exposure to BIP,+,BH4 and there was no effect in mtDNA copy number. In conclusion, the present results show that HS-induced apoptosis in bovine oocytes involves Bax and BH4 domain-dependent pathways. Mol. Reprod. Dev. 76: 637,646, 2009. © 2008 Wiley-Liss, Inc. [source] Arabidopsis Bax inhibitor-1 functions as an attenuator of biotic and abiotic types of cell deathTHE PLANT JOURNAL, Issue 6 2006Naohide Watanabe Summary Programmed cell death (PCD) is a common process in eukaryotes during development and in response to pathogens and stress signals. Bax inihibitor-1 (BI-1) is proposed to be a cell death suppressor that is conserved in both animals and plants, but the physiological importance of BI-1 and the impact of its loss of function in plants are still unclear. In this study, we identified and characterized two independent Arabidopsis mutants with a T-DNA insertion in the AtBI1 gene. The phenotype of atbi1-1 and atbi1-2, with a C-terminal missense mutation and a gene knockout, respectively, was indistinguishable from wild-type plants under normal growth conditions. However, these two mutants exhibit accelerated progression of cell death upon infiltration of leaf tissues with a PCD-inducing fungal toxin fumonisin B1 (FB1) and increased sensitivity to heat shock-induced cell death. Under these conditions, expression of AtBI1 mRNA was up-regulated in wild-type leaves prior to the activation of cell death, suggesting that increase of AtBI1 expression is important for basal suppression of cell death progression. Over-expression of AtBI1 transgene in the two homozygous mutant backgrounds rescued the accelerated cell death phenotypes. Together, our results provide direct genetic evidence for a role of BI-1 as an attenuator for cell death progression triggered by both biotic and abiotic types of cell death signals in Arabidopsis. [source] Fas/CD95/APO-1 Can Function as a Death Receptor for Neuronal Cells in Vitro and in Vivo and is Upregulated Following Cerebral Hypoxic-Ischemic Injury to the Developing Rat BrainBRAIN PATHOLOGY, Issue 1 2000Ursula Felderhoff-Mueser Fas/CD95/Apo-1 is a cell surface receptor that transduces apoptotic death signals following activation and has been implicated in triggering apoptosis in infected or damaged cells in disease states. Apoptosis is a major mechanism of neuronal loss following hypoxic-ischemic injury to the developing brain, although the role of Fas in this process has not been studied in detail. In the present study, we have investigated the expression and function of Fas in neuronal cells in vitro and in vivo. Fas was found to be expressed in the 14 day old rat brain, with strongest expression in the cortex, hippocampus and cerebellum. Cross-linking of Fas induced neuronal apoptosis both in neuronal PC12 cells in culture and following intracerebral injection in vivo, indicating that neuronal Fas was functional as a death receptor. This death was shown to be caspase dependent in primary neuronal cultures and was blocked by the selective caspase 8 inhibitor IETD. Finally, cerebral hypoxia-ischemia resulted in a strong lateralised upregulation of Fas in the hippocampus, that peaked six to twelve hours after the insult and was greater on the side of injury. These results suggest that Fas may be involved in neuronal apoptosis following hypoxic-ischemic injury to the developing brain. [source] | |||||||||||||