Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increasing evidence suggests that lysosomal proteases are actively involved in apoptosis. Using HeLa cells as the model system, we show that selective lysosome disruption with L-leucyl-L-leucine methyl ester results in apoptosis, characterized by translocation of lysosomal proteases into the cytosol and by the cleavage of a proapoptotic Bcl-2-family member Bid. Apoptosis and Bid cleavage, but not translocation of lysosomal proteases to the cytosol, could be prevented by 15 microM L-trans-epoxysuccinyl(OEt)-Leu-3-methylbutylamide, an inhibitor of papain-like cysteine proteases. Incubation of cells with 15 microM N-benzoyloxycarbonyl-VAD-fluoromethyl ketone prevented apoptosis but not Bid cleavage, suggesting that cathepsin-mediated apoptosis in this system is caspase-dependent. In vitro experiments performed at neutral pH showed that papain-like cathepsins B, H, L, S, and K cleave Bid predominantly at Arg(65) or Arg(71). No Bid cleavage was observed with cathepsins C and X or the aspartic protease cathepsin D. Incubation of full-length Bid treated with cathepsins B, H, L, and S resulted in rapid cytochrome c release from isolated mitochondria. Thus, Bid may be an important mediator of apoptosis induced by lysosomal disruption.
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PMID:Selective disruption of lysosomes in HeLa cells triggers apoptosis mediated by cleavage of Bid by multiple papain-like lysosomal cathepsins. 1458 76

Ribosomal proteins (RP) S13 and RPL23 were previously identified as two upregulated genes in a multidrug-resistant gastric cancer cell line SGC7901/VCR compared to its parental cell SGC7901 by differential display PCR. The aim of this study was to explore the roles of RPS13 and RPL23 in multidrug resistance (MDR) in gastric cancer cells. RPS13 and RPL23 were genetically overexpressed in SGC7901 cells, respectively. Either RPS13 or RPL23 enhanced resistance of SGC7901 cells to vincristine, adriamycin, and 5-fludrouracil. RPL23 also enhanced resistance of SGC7901 cells to cisplatin. Overexpression of either RPS13 or RPL23 did not alter the population doubling time, [3H]leucine incorporation, and intracellular adriamycin accumulation of SGC7901 cells. However, either RPS13 or RPL23 could protect SGC7901 cells from undergoing vincristine-induced apoptosis. Western blot analysis revealed that both RPS13 and RPL23 significantly increased the expression level of Bcl-2 and Bcl-2/Bax ratio in SGC7901 cells. In addition, overexpression of RPL23 enhanced glutathione S-transferase (GST) activity and intracellular glutathione content in SGC7901 cells. Together, this work demonstrates that either RPS13 or RPL23 can promote MDR in gastric cancer cells by suppressing drug-induced apoptosis, and that RPL23 may also promote MDR in gastric cancer cells through regulation of glutathione S-transferase-mediated drug-detoxifying system.
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PMID:Ribosomal proteins S13 and L23 promote multidrug resistance in gastric cancer cells by suppressing drug-induced apoptosis. 1514 63

Proliferation of small blood vessels in synovial tissues is one of the pathologic features of rheumatoid arthritis. In this study we tested the hypothesis that nitric oxide (NO) protects endothelial cells (ECs) against apoptogenic agents in vitro. Human umbilical-vein endothelial cells (HUVECs) were cultured with and without NO donor S -nitro- N -acetylpenicillamine (SNAP) and further incubated in the presence or absence of Z-leucine-leucine-leucine-aldehyde (LLL-CHO), etoposide, or C2-ceramide. After cultivation, apoptosis of HUVECs was quantified on the basis of disruption of mitochondrial transmembrane potential (DeltaPsim), activation of caspases, and the presence of hypodiploid DNA-positive cells. Treatment of HUVECs with LLL-CHO, etoposide, or C2-ceramide induced DeltaPsim, activation of caspase-3, caspase-8, and caspase-9 and the appearance of hypodiploid DNA-positive cells. NO production in HUVECs was clearly increased by SNAP. Apoptotic cell death in HUVECs induced by LLL-CHO, etoposide, and C2-ceramide was significantly suppressed by SNAP treatment. HUVECs in vitro expressed Bcl-2, Bcl-xL, and Bax; however, expression was not changed by SNAP treatment in the presence or absence of LLL-CHO, etoposide, or C2-ceramide. Although the molecule(s) responsible for the protective effects of NO remains to be identified, our data imply that NO protects HUVECs against mitochondrial perturbation caused by apoptogenic agents. These results suggest that NO promotes endothelial-cell proliferation and angiogenesis in the synovial tissues of patients with rheumatoid arthritis and that NO may be a therapeutic target for rheumatoid arthritis.
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PMID:Nitric oxide acts on the mitochondria and protects human endothelial cells from apoptosis. 1545 84

Human papillomavirus type 16 E5 protein contributes to cellular transformation by increasing the mitogenic stimulus from growth factor receptors to the nucleus. In order to study the biological mechanisms of the E5 protein we performed site-directed mutagenesis of the E5 gene. Wild-type as well as mutant E5 proteins were transiently expressed in human cervical epithelial cells, and cell morphology, expression of proteins involved in cell adhesion, and localization of the different proteins were studied. Little differences in cell morphology or expression kinetics were observed between the different E5 proteins, except for relocalization of a mutant E5 protein where a hydrophobic leucine membrane anchor was mutated to positively charged amino acids. This mutant E5 protein localized to lamellipodia, which are motility-associated structures at the leading edge of motile cells. In our experimental conditions, 100% of E5-expressing epithelial cells died by four days of expression, possibly due to toxicity or disturbance of the membrane compartment by the E5 protein. Most interestingly, a remarkable colocalization of the E5 protein with the Bcl-2 antiapoptotic protein on intracellular membranes was established.
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PMID:Human papillomavirus type 16 E5 protein colocalizes with the antiapoptotic Bcl-2 protein. 1559 17

An Escherichia coli plasmid vector for the high-level expression of hydrophobic membrane proteins is described. The plasmid, pBCL, directs the expression of a target polypeptide fused to the C terminus of a mutant form of the anti-apoptotic Bcl-2 family protein, Bcl-XL, where the hydrophobic C terminus has been deleted, and Met residues have been mutated to Leu to facilitate CNBr cleavage after a single Met inserted at the beginning of the target sequence. Fusion protein expression is in inclusion bodies, simplifying the protein purification steps. Here we report the high-level production of PLM, a membrane protein that is a member of the FXYD family of tissue-specific and physiological-state-specific auxiliary subunits of the Na,K-ATPase, expressed abundantly in heart and skeletal muscle. We demonstrate that milligram quantities of pure, isotopically labeled protein can be obtained easily and in little time with this system.
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PMID:Bcl-XL as a fusion protein for the high-level expression of membrane-associated proteins. 1574 45

The anti-apoptotic members of the Bcl-2 family, such as Bcl-2 and Bcl-XL, play a central role in preventing the induction of apoptosis via the intrinsic apoptotic pathway. It has been previously shown that induction of apoptosis by the pro-apoptotic Bcl-2 family member Bok is not antagonized by either Bcl-2 or Bcl-xL, suggesting that Bok might have a unique role in the apoptotic cascade. We showed here that human Bok is the only member of the Bcl-2 family to have a leucine-rich sequence indicative of a nuclear export signal within its BH3 domain. Western blot analysis of nuclear and cytoplasmic fractions identified Bok in both the nucleus and the cytoplasm of HEK 293T cells, HeLa cells, and breast cancer cells, and its nuclear concentration increased after treatment of those cells with leptomycin B, an inhibitor of the exportin Crm1. Immunocytochemistry of flag-tagged Bok confirmed its nuclear localization. Mutating the nuclear export signal of Bok by site-directed mutagenesis resulted in an increase in its nuclear localization and apoptotic activity. We also found that Crm1 interacted with wild-type Bok but not with the mutated form. These results suggest that nuclear export of Bok is a regulated process mediated by Crm1, and constitutes the first report of a link between the apoptotic activity and nuclear localization of a pro-apoptotic member of the Bcl-2 family.
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PMID:Nuclear translocation of the pro-apoptotic Bcl-2 family member Bok induces apoptosis. 1630 69

Notch receptor-mediated intracellular events represent an ancient cell signaling system, and alterations in Notch expression are associated with various malignancies in which Notch may function as an oncogene or less commonly as a tumor suppressor. Notch signaling regulates cell fate decisions in the epidermis, including influencing stem cell dynamics and growth/differentiation control of cells in skin. Because of increasing evidence that the Notch signaling network is deregulated in human malignancies, Notch receptors have become attractive targets for selective killing of malignant cells. Compared with proliferating normal human melanocytes, melanoma cell lines are characterized by markedly enhanced levels of activated Notch-1 receptor. By using a small molecule gamma-secretase inhibitor (GSI) consisting of a tripeptide aldehyde, N-benzyloxycarbonyl-Leu-Leu-Nle-CHO, which can block processing and activation of all four different Notch receptors, we identified a specific apoptotic vulnerability in melanoma cells. GSI triggers apoptosis in melanoma cells, but only G2/M growth arrest in melanocytes without subsequent cell death. Moreover, GSI treatment induced a pro-apoptotic BH3-only protein, NOXA, in melanoma cells but not in normal melanocytes. The use of GSI to induce NOXA induction overcomes the apoptotic resistance of melanoma cells, which commonly express numerous cell survival proteins such as Mcl-1, Bcl-2, and survivin. Taken together, these results highlight the concept of synthetic lethality in which exposure to GSI, in combination with melanoma cells overexpressing activated Notch receptors, has lethal consequences, producing selective killing of melanoma cells, while sparing normal melanocytes. By identifying signaling pathways that contribute to the transformation of melanoma cells (e.g. Notch signaling), and anti-cancer agents that achieve tumor selectivity (e.g., GSI-induced NOXA), this experimental approach provides a useful framework for future therapeutic strategies in cutaneous oncology.
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PMID:Notch and NOXA-related pathways in melanoma cells. 1636 61

(DIPP-L-Leu)2-L-LysOCH3 is a diisopropylphosphoryl dipeptide which is known to induce apoptosis of human leukemia K562 cells. The molecular and cellular mechanisms involved in this process remain to be clarified. Herein, we show that (DIPP-L-Leu)2-L-LysOCH3-induced apoptosis is associated with cytosolic accumulation of cytochrome c, sustained loss of mitochondrial transmembrane potential (MMP), transient generation of reactive oxygen species (ROS) and elevation of intracellular Ca2+ concentration. A specific caspase assay reveals an increase in caspase-9 and caspase-3 activity but no change in caspase-8 activity. Immunofluorescence analysis indicates that (DIPP-L-Leu)2-L-LysOCH3 induced upregulation of pro-apoptotic Bax and downregulation of anti-apoptotic Bcl-2 and Bcl-x(L). These results suggest that the mitochondria-regulated death pathway mediates (DIPP-L-Leu)2-L-LysOCH3-induced K562 cells apoptosis.
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PMID:Mitochondria-regulated death pathway mediates (DIPP-L-Leu)2-L-LysOCH3-induced K562 cells apoptosis. 1647 74

The pathway of interferon-gamma (IFN-gamma)-induced suppression in tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-mediated apoptosis of fibroblast-like synovial cells (FLS) was investigated. rTRAIL triggered FLS apoptosis in a type II cell death manner, whereas IFN-gamma pretreatment significantly inhibited TRAIL-mediated apoptosis. As disruption of mitochondrial transmembrane potential (DeltaPsim), Leu-Glu-His-Asp ase (IETD ase) activity, and the appearance of hypodiploid DNA + cells were markedly suppressed in IFN-gamma-treated FLS in response to TRAIL, IFN-gamma-induced suppression was supposed to achieve at upstream of caspase-8. IFN-gamma rapidly phosphorylated signal transducers and activators of transcription 1 (STAT1), STAT3, and STAT6 as well as ERK, whereas enhanced neither phosphorylation of Akt nor nuclear translocation of nuclear factor kappaB (NF-kappaB) p65. Janus kinase (JAK)-induced phosphorylation of STAT1/3/6, which acts at translational regulation, seemed to be crucial because chemical inhibition of JAK as well as cycloheximide (CHX) abolished both the phosphorylation of STAT1/3/6 and the IFN-gamma-induced inhibitory effect. Although ERK was phosphorylated through IFN-gamma, chemical inhibition of ERK by PD98059 did not abolish the IFN-gamma-induced inhibitory effect. The authors tried to determine the responsible molecules; however, expression of TRAIL receptors; pro-caspase-3/-8/-9; Fas-associated death domain protein (FADD); tumor necrosis factor receptor 1-associated death domain protein (TRADD); silencer of death domain (SODD); FLICE inhibitory protein (FLIP); and Bcl-2, Bcl-xL, and Bax in FLS was not modulated by IFN-gamma. Although the authors have not yet clarified the precise mechanism, these data suggest that IFN-gamma/JAK/STAT pathway, which is supposed to be activated in inflammatory rheumatoid arthritis (RA) synovial tissues, contributes to form apoptosis resistance phenotype of the cells in situ, leading to a marked increase in cellularity of synovial cells.
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PMID:Significant inhibition of TRAIL-mediated fibroblast-like synovial cell apoptosis by IFN-gamma through JAK/STAT pathway by translational regulation. 1658 46

Apoptosis signaling pathways are implicated in the pathogenesis of temporal lobe epilepsy (TLE), but the role of endoplasmic reticulum (ER) stress and ER-localized apoptosis signaling components remains largely unexplored. Presently, we investigated ER stress and ER localization of proapoptotic Bcl-2 family members and initiator and effector caspases in resected hippocampus from patients with intractable TLE and compared findings with autopsy controls. Hippocampal immunoreactivity for KDEL (Lys-Asp-Glu-Leu), a motif in ER stress chaperones glucose-regulated proteins 78 and 94, and calnexin, was significantly higher in TLE hippocampus compared with controls. The ER-containing microsomal fraction in control brain contained Bid, Bim, and caspase 3, whereas Bad and caspases 6, 7, and 9 were very low or absent. In contrast, caspases 6, 7, and 9 were present within the microsomal fraction of TLE brain. Furthermore, cleaved caspases 7 and 9 were detected in TLE samples but not controls, and KDEL-expressing neurons coexpressed cleaved caspase 9. Potentially adaptive changes were also detected, including lowered Bim levels in this fraction, and binding of caspase 7 to the X-linked inhibitor of apoptosis protein. These data suggest seizures may induce ER stress and trigger proapoptotic signaling pathways in the ER that are counteracted by antiapoptotic signals in chronic human TLE.
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PMID:Endoplasmic reticulum stress and apoptosis signaling in human temporal lobe epilepsy. 1665 83


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