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)

The molecular mechanisms underlying the initiation and control of the release of cytochrome c during mitochondrion-dependent apoptosis are thought to involve the phosphorylation of mitochondrial Bcl-2 and Bcl-x(L). Although the c-Jun N-terminal kinase (JNK) has been proposed to mediate the phosphorylation of Bcl-2/Bcl-x(L) the mechanisms linking the modification of these proteins and the release of cytochrome c remain to be elucidated. This study was aimed at establishing interdependency between JNK signalling and mitochondrial apoptosis. Using an experimental model consisting of isolated, bioenergetically competent rat brain mitochondria, these studies show that (i) JNK catalysed the phosphorylation of Bcl-2 and Bcl-x(L) as well as other mitochondrial proteins, as shown by two-dimensional isoelectric focusing/SDS/PAGE; (ii) JNK-induced cytochrome c release, in a process independent of the permeability transition of the inner mitochondrial membrane (imPT) and insensitive to cyclosporin A; (iii) JNK mediated a partial collapse of the mitochondrial inner-membrane potential (Deltapsim) in an imPT- and cyclosporin A-independent manner; and (iv) JNK was unable to induce imPT/swelling and did not act as a co-inducer, but as an inhibitor of Ca-induced imPT. The results are discussed with regard to the functional link between the Deltapsim and factors influencing the permeability transition of the inner and outer mitochondrial membranes. Taken together, JNK-dependent phosphorylation of mitochondrial proteins including, but not limited to, Bcl-2/Bcl-x(L) may represent a potential of the modulation of mitochondrial function during apoptosis.
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PMID:c-Jun N-terminal kinase (JNK)-mediated modulation of brain mitochondria function: new target proteins for JNK signalling in mitochondrion-dependent apoptosis. 1261 94

Mitochondria-mediated apoptosis is regulated by proteins of the Bcl-2 superfamily, most of which contain a C-terminal hydrophobic domain that plays a role in membrane targeting. Experiments with BNIP3 have implicated the transmembrane (TM) domain in its proapoptotic function, homodimerization, and interactions with Bcl-2 and Bcl-xL. We show that the BNIP3 TM domain self-associates strongly in Escherichia coli cell membranes and causes reversible dimerization of a soluble protein in the detergent SDS when expressed as an in-frame fusion. Limited mutational analysis identifies specific residues that are critical for BNIP3 TM self-association in membranes, and these residues are also important for dimerization in SDS micelles, suggesting that the self-association observed in membranes is preserved in detergent. The effects of sequence changes at positions Ala176 and Gly180 suggest that the BNIP3 TM domain associates using a variant of the GXXXG motif previously shown to be important in the dimerization of glycophorin A. The importance of residue His173 in BNIP3 TM domain dimerization indicates that polar residues, which have been implicated in self-association of model TM peptides, can act in concert with the AXXXG motif to stabilize TM domain interactions. Our results demonstrate that the hydrophobic C-terminal TM domain of the pro-apoptotic BNIP3 protein dimerizes tightly in lipidic environments, and that this association has a strong sequence dependence but is independent of the identity of flanking regions. Thus, the transmembrane domain represents another region of the Bcl-2 superfamily of proteins that is capable of mediating strong and specific protein-protein interactions.
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PMID:Sequence-specific dimerization of the transmembrane domain of the "BH3-only" protein BNIP3 in membranes and detergent. 1453 63

Familial amyotrophic lateral sclerosis (ALS)-linked mutations in the copper-zinc superoxide dismutase (SOD1) gene cause motor neuron death in about 3% of ALS cases. While the wild-type (wt) protein is anti-apoptotic, mutant SOD1 promotes apoptosis. We now demonstrate that both wt and mutant SOD1 bind the anti-apoptotic protein Bcl-2, providing evidence of a direct link between SOD1 and an apoptotic pathway. This interaction is evident in vitro and in vivo in mouse and human spinal cord. We also demonstrate that in mice and humans, Bcl-2 binds to high molecular weight SDS-resistant mutant SOD1 containing aggregates that are present in mitochondria from spinal cord but not liver. These findings provide new insights into the anti-apoptotic function of SOD1 and suggest that entrapment of Bcl-2 by large SOD1 aggregates may deplete motor neurons of this anti-apoptotic protein.
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PMID:Amyotrophic lateral sclerosis-associated SOD1 mutant proteins bind and aggregate with Bcl-2 in spinal cord mitochondria. 1523 14

The addition of tumor necrosis factor (TNF)-alpha into the cultured porcine kidney LLC-PK1 cells caused apoptosis concomitantly with caspase-3 activation and the inductions of an endogenous Bcl-2 protein. An SDS-polyacrylamide electrophoretic analysis revealed that a 37-kDa protein in a nuclear fraction was increased during TNF-alpha-induced apoptosis. Partial amino acid sequence of the protein was A-L-T-G-H-L-E-E-V, perfectly matching that of annexin I. Immunocytochemistry revealed that annexin I migrated to the nucleus and/or peri-nucleus region upon exposure to TNF-alpha. Overexpression of Bcl-2 proteins inhibited the nuclear localization of annexin I during TNF-alpha-induced apoptosis. Antisense oligodeoxynucleotides complementary to annexin I-inhibited TUNEL (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labelling) staining in TNF-alpha-treated cells, suggesting that annexin I expression is a possible prerequisite for the induction of apoptosis by the cytokine. Thus, it is first time to show that annexin I is regulated by an anti-apoptotic Bcl-2 protein in TNF-alpha-induced renal apoptotic events.
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PMID:Overexpression of Bcl-2 inhibits nuclear localization of annexin I during tumor necrosis factor-alpha-mediated apoptosis in porcine renal LLC-PK1 cells. 1554 40

Members of the Bcl-2 family of proteins play important roles in the regulation of cell death by apoptosis. The yeast Two-Hybrid system was utilized to identify a protein that interacts with the anti-apoptotic protein Bcl-2, designated BMRP. This protein corresponds to a previously known mitochondrial ribosomal protein (MRPL41). Binding experiments confirmed the interaction of BMRP to Bcl-2 in mammalian cells. Subcellular fractionation by differential centrifugation studies showed that both Bcl-2 and BMRP are localized to the same fractions (fractions that are rich in mitochondria). Northern blot analysis revealed a major bmrp mRNA band of approximately 0.8 kb in several human tissues. Additionally, a larger 2.2 kb mRNA species was also observed in some tissues. Western blot analysis showed that endogenous BMRP runs as a band of 16-17 kDa in SDS-PAGE. Overexpression of BMRP induced cell death in primary embryonic fibroblasts and NIH/3T3 cells. Transfection of BMRP showed similar effects to those observed by overexpression of the pro-apoptotic proteins Bax or Bad. BMRP-stimulated cell death was counteracted by co-expression of Bcl-2. The baculoviral caspase inhibitor p35 also protected cells from BMRP-induced cell death. These findings suggest that BMRP is a mitochondrial ribosomal protein involved in the regulation of cell death by apoptosis, probably affecting pathways mediated by Bcl-2 and caspases.
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PMID:BMRP is a Bcl-2 binding protein that induces apoptosis. 1554 50

The objective of this study was to investigate the alteration of the protein profile in cells after sonication and to identify the key proteins involved in the process of cell apoptosis. Walker 256 carinosarcoma cells were exposed to focused ultrasound (US) at the intensity of 2.0, 7.0, 10.2, 14.2 and 17.0 W/cm2 (I(spta)) for 10 min in vitro and the morphologic and functional changes of the cells were detected by hematoxylin & eosin staining and flow cytometry, with double staining of fluorescein isothiocyanate (FITC)-labeled Annexin V/propidium iodide (PI). The protein compositions in the cells after sonication were detected by 2-D SDS polyacrylamide gel electrophoresis. Our results showed that apoptosis of Walker 256 carinosarcoma cells could be induced by US. The percentage of early apoptosis and secondary necrosis increased with increasing intensity of US irradiation. Comparing with the protein patterns of cells before sonication, it was found that around 420 new protein spots were present in the gel after sonication. Among them, Hsp60 and Bcl-2 like protein 13 were found to be involved in the process of cell apoptosis and US-induced apoptosis of the cells was probably performed through the pathway of promoting the activation of caspase-3.
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PMID:The alteration of protein profile of Walker 256 carinosarcoma cells during the apoptotic process induced by ultrasound. 1565 39

The present study evaluates the phenotypic and genotypic changes that take place during early oncogenesis. The submandibular glands of male rats were injected with a 0.5% solution of 9,10-dimethyl-1,2-benzanthracene (DMBA) in acetone. Gland samples were taken at 0, 7, 30 and 150 days post-injection and submitted to histological, biochemical, immunocytochemical and PCR evaluation. Histopathological analysis was performed on hematoxylin-eosin stained slides. Total protein content was assessed by Lowry's method and the protein profile was analyzed by 12% SDS-PAGE. Bcl-2 was demonstrated by silver-enhanced gold immunolabeling. p53 immunolabeling was performed using the streptavidin-biotin system. All the treated animals developed carcinoma-like lesions at 30 and 150 days. Total protein concentration rose significantly (p < 0.05) above control values at 7, 30 and 150 days. The treated glands exhibited positive immunolabeling for p53 in the nuclei of neoplastic cells at 30 and 150 days. Treated glands also showed positive cytoplasmic immunolabeling for Bcl-2, exhibiting statistically significant differences between 7, 30 and 150 days (p = 0.0015), and with controls (p < 0.0001). No p53 mutations were observed whereas a point mutation, C-to-A, of the Bcl-2 gene was detected at 7, 30 and 150 days by PCR amplification. This mutation led to a single aminoacid change (thre --> asn) in the protein molecule. Our results suggest that the early histopathological changes correspond to quantitative and qualitative protein changes. The histopathological, biochemical, immunocytochemical and genetic alterations observed during the course of experimental carcinogenesis in the submandibular gland of the rat could constitute reproducible indices of malignant transformation applicable to human oncogenesis, given the high degree of homology between the oncogenes of mice, rats and human beings.
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PMID:Early phenotypic and genotypic alterations in submandibular gland oncogenesis in rats. 1712 Nov 94

The rapid cold-hardening (RCH) response increases the cold tolerance of insects by protecting against non-freezing, cold-shock injury. Apoptosis, or programmed cell death, plays important roles in development and the elimination of sub-lethally damaged cells. Our objectives were to determine whether apoptosis plays a role in cold-shock injury and, if so, whether the RCH response protects against cold-induced apoptosis in Drosophila melanogaster. The present study confirmed that RCH increased the cold tolerance of the adults at the organismal level. No flies in the cold-shocked group survived direct exposure to 7 degrees C for 2 h, whereas significantly more flies in the RCH group survived exposure to 7 degrees C for 2 h after a 2-h exposure to 5 degrees C. We used a TUNEL assay to detect and quantify apoptotic cell death in five groups of flies including control, cold-shocked, RCH, heat-shocked (37.5 degrees C, 30 min), and frozen (20 degrees C, 24 h) and found that apoptosis was induced by cold shock, heat shock, and freezing. The RCH treatment significantly improved cell viability by 38% compared to the cold-shocked group. Cold shock-induced DNA fragmentation shown by electrophoresis provided further evidence for apoptosis. SDS-PAGE analysis revealed an RCH-specific protein band with molecular mass of approximately 150 kDa. Western-blotting revealed three proteins that play key roles in the apoptotic pathway: caspase-9-like (apoptotic initiator), caspase-3-like (apoptotic executioner) and Bcl-2 (anti-apoptotic protein). Consequently, the results of this study support the hypothesis that the RCH response protects against cold-shock-induced apoptosis.
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PMID:Rapid cold-hardening protects Drosophila melanogaster from cold-induced apoptosis. 1724 39

This study aims to investigate the role of granzyme B in the apoptosis of nasal-type NK/T-cell lymphoma. Twenty-four nasal-type NK/T-cell lymphomas were examined by TdT-mediated deoxyuridine triphosphate (dUTP)-biotin nick-end labeling (TUNEL) assay and immunohistochemical staining for active caspase 3, poly(ADP-ribose) polymerase (PARP-1/p85)/p85, and Bcl-2. In addition, HANK-1 and NKL cell lines were analyzed using Western blot analysis. Immunoprecipitation was performed to identify the binding of granzyme B and intrinsic serpin proteinase inhibitor 9 (PI-9). To localize granzyme B, immunogold labeling and immunofluorescence staining were performed. The expression level of granzyme B in tumor tissue was correlated with the apoptosis rate (P=0.015), degree of necrosis (P=0.002), and the levels of active caspase 3 (P=0.036) and poly ADP-ribose polymerase (PARP)-1/p85 (P=0.040). The granzyme B-positive HANK-1 cell line showed increased spontaneous cell death compared to the granzyme B-negative NKL cell line. The untreated HANK-1 cells released cytochrome c into the cytosol with cleavage of caspase 3 and PARP-1. Treatment with granzyme B inhibitor and caspase inhibitor decreased the cleavage of PARP-1. By performing immunogold labeling, granzyme B was identified within the cytolytic granules as well as in the cytosol. Confocal microscopy and immunoprecipitation assays confirmed the colocalization of PI-9 and granzyme B, which formed an SDS-resistant complex. These results suggested that granzyme B leakage induces cell death in NK/T-cell lymphomas via both caspase-dependent and -independent mechanisms, and this leads to the extensive necrosis that is commonly seen in NK/T-cell lymphoma.
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PMID:Granzyme B leakage-induced apoptosis is a crucial mechanism of cell death in nasal-type NK/T-cell lymphoma. 1726 2

Bnip3 is a proapoptotic member of the Bcl-2 family of death-regulating proteins that promote the intrinsic pathway of programmed cell death. The Bnip3 death program requires membrane insertion through an N-terminal transmembrane domain that directs the protein to mitochondrial and endoplasmic reticular (ER) membranes. We have reported that simulated ischemia induces transcription of the Bnip3 gene, and Bnip3 protein is stabilized by acidosis. Bnip3 programmed death is atypical, with features of both apoptosis and necrosis. Here we demonstrate that hypoxia-reoxygenation and agents that activate protein kinase C, including calcium ionophore, phorbol 12-myristate 13-acetate, and okadaic acid, also induce Bnip3. The molecular size of Bnip3 predicted from the amino acid sequence is 21.5 kDa, but the protein typically migrates in SDS-PAGE as a 31-kDa monomer and 60-kDa dimer. Treatment of cell extracts containing Bnip3 with phosphatase yielded a series of rapidly migrating species, the smallest of which corresponded with the theoretic molecular size of Bnip3. Conversely, treatment of cells with okadaic acid eliminated the rapidly migrating species, suggesting that Bnip3 phosphorylation is a dynamic process. Elevated levels of the phosphoprotein correlated with initiation of Bnip3-dependent death, whereas the dephosphorylated species correlated with extreme acidosis.
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PMID:Regulation of Bnip3 death pathways by calcium, phosphorylation, and hypoxia-reoxygenation. 1763 46


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