UNIPROT:P10415 - FACTA Search

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Query: UNIPROT:P10415 (Bcl-2)
33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the developing liver, the complete or partial persistence of the primitive double-layered cylinder of biliary-type cells that surrounds the branches of portal vein and its mesenchyme gives origin to portal tracts with an increased number of bile duct structures. The term "ductal plate malformation of the liver" was coined to label the insufficient remodeling of the primitive intrahepatic biliary system. Meckel syndrome is an autosomal recessive inherited disease characterized by occipital encephalocele, postaxial polydactyly, diffuse cystic renal dysplasia, and malformation of the ductal plate of the liver. We studied 52 fetuses with Meckel syndrome from five German centers (Berlin, Freiburg, Heidelberg, Mainz, and Marburg). Analysis of apoptosis and cell proliferation (Ki-67) was performed by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) and immunohistochemistry in the liver of 24 normal fetuses of different gestational ages (14-38 weeks of gestation) and in 14 fetuses with Meckel syndrome (17-38 weeks of gestation). The expression of two apoptosis-related proteins, Fas (a transmembrane cell surface protein involved in the apoptosis) and Bcl-2 (an anti-apoptotic protein), was studied by immunohistochemistry in the liver of 11 normal fetuses of different gestational ages (14-40 weeks of gestation) and in 40 fetuses with Meckel syndrome (16-38 weeks of gestation). In control fetuses, apoptosis rate and cell proliferation were high in the remodeling ductal plate and moderate in the ductal plate and in remodeled bile ducts. During gestation, expression of Fas and Bcl-2 decreased and increased, respectively. The malformed ductal plates in the fetal livers with Meckel syndrome showed a marked decrease in the apoptotic rate and Fas expression and an increase in proliferative activity and Bcl-2 expression in comparison with control fetuses. Furthermore, by linear regression analysis, we found that both proliferation activity and apoptosis rate in the ductal plate malformation of fetuses with Meckel syndrome were practically constant along the gestation. These results, which represent the first systematic study of apoptosis in ductal plate malformation of the liver, indicate that 1) animals harboring the gene defect of Meckel syndrome could be a good model for the study of the abnormal development of the primitive intrahepatic biliary system, 2) a decreased cell turnover occurs in the ductal plate malformation of fetuses with Meckel syndrome, and 3) the increase of Bcl-2 expression contributes to the pathogenesis of the lack of remodeling of ductal plate of the liver in Meckel syndrome.
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PMID:Contribution of apoptosis and apoptosis-related proteins to the malformation of the primitive intrahepatic biliary system in Meckel syndrome. 1079 71

In the present study, we have aimed at clarifying the CD4-dependent molecular mechanisms that regulate human memory T cell susceptibility to both Fas (CD95)-dependent and Bcl-2-dependent apoptotic pathways following antigenic challenge. To address this issue, we used an experimental system of viral and alloantigen-specific T cell lines and clones and two ligands of CD4 molecules, Leu-3a mAb and HIV gp120. We demonstrate that CD4 engagement before TCR triggering suppresses the TCR-mediated neosynthesis of the Flice-like inhibitory protein and transforms memory T cells from a CD95-resistant to a CD95-susceptible phenotype. Moreover, evidence that the apoptotic programs were executed while Fas ligand mRNA expression was inhibited led us to analyze Bcl-2-dependent pathways. The data show that the engagement of CD4 separately from TCR influences the expression of the proapoptotic protein Bax independently of the anti-apoptotic protein Bcl-2, whereas Ag activation coordinately modulates both Bax and Bcl-2. The increased expression of Bax and the consequent dissipation of the mitochondrial transmembrane potential (DeltaPsim) suggest a novel immunoregulatory function of CD4 and demonstrate that both passive cell death and activation-induced cell death are operative in CD4+ memory T cells. Furthermore, analysis of the mechanisms by which IL-2 and IL-4 cytokines exert their protective function on CD4+ T cells in the presence of soluble CD4 ligands shows that they were able to revert susceptibility to Bax-mediated but not to CD95-dependent apoptotic pathways.
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PMID:Engagement of CD4 before TCR triggering regulates both Bax- and Fas (CD95)-mediated apoptosis. 1079 64

The regulation of proliferation and cell death is vital for homeostasis, but the mechanism that coordinately balances these events in rheumatoid arthritis (RA) remains largely unknown. In RA, the synovial lining thickens in part through increased proliferation and/or decreased synovial fibroblast cell death. Here we demonstrate that the anti-apoptotic protein, Bcl-2, is highly expressed in RA compared with osteoarthritis synovial tissues, particularly in the CD68-negative, fibroblast-like synoviocyte population. To determine the importance of endogenous Bcl-2, an adenoviral vector expressing a hammerhead ribozyme to Bcl-2 (Ad-Rbz-Bcl-2) mRNA was employed. Ad-Rbz-Bcl-2 infection resulted in reduced Bcl-2 expression and cell viability in synovial fibroblasts isolated from RA and osteoarthritis synovial tissues. In addition, Ad-Rbz-Bcl-2-induced mitochondrial permeability transition, cytochrome c release, activation of caspases 9 and 3, and DNA fragmentation. The general caspase inhibitor zVAD.fmk blocked caspase activation, poly(ADP-ribose) polymerase cleavage, and DNA fragmentation, but not loss of transmembrane potential or viability, indicating that cell death was independent of caspase activation. Ectopically expressed Bcl-xL inhibited Ad-Rbz-Bcl-2-induced mitochondrial permeability transition and apoptosis in Ad-Rbz-Bcl-2-transduced cells. Thus, forced down-regulation of Bcl-2 does not induce a compensatory mechanism to prevent loss of mitochondrial integrity and cell death in human fibroblasts.
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PMID:Bcl-2 expression in synovial fibroblasts is essential for maintaining mitochondrial homeostasis and cell viability. 1079 83

The subventricular zone (SVZ) is an embryonic remnant that persists and remains mitotically active throughout adulthood. The rodent SVZ harbors neuronal precursors, principally in its anterior part, and generates neuroblasts that migrate tangentially into the olfactory bulb, thus forming the so-called rostral migratory stream. This study aimed at characterizing the SVZ in the human brain. Antibodies raised against the widely used SVZ molecular markers nestin, glial fibrillary acidic protein, beta-tubulin-III and polysialylated neural cell adhesion molecule, have allowed us to characterize in detail a zone similar to the rodent SVZ in humans. Virtually all portions of the lateral ventricle, as well as the ventral (hypothalamic) sector of the third ventricle, displayed immunoreactivity for most of the molecular markers. The midline region of the septum (septal recess) and the ventral portion of the SVZ displayed a particularly intense immunostaining for all SVZ markers. These two regions may represent zones of adult neurogenesis that are unique to primates. Furthermore, the anti-apoptotic protein Bcl-2 was found to be actively synthesized and co-expressed with all the other markers throughout the entire SVZ. This study reveals that a well-developed SVZ exists in the adult human brain and suggests that Bcl-2 might play an important role in the functional organization of such a system.
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PMID:Characterization of the subventricular zone of the adult human brain: evidence for the involvement of Bcl-2. 1080 45

The role of Bcl-2 as an anti-apoptotic protein has been well documented. In the present work, we present evidence that Bcl-2 may also be involved in cell growth regulation. SC-M1 is an unique cell line which responds to retinoic acid (RA) treatment with reversible growth arrest [Shyu, Jiang, Huang, Chang, Wu, Roffler and Yeh (1995) Eur. J. Cancer 31, 237-243]. In this study, when treated with RA, SC-M1/Bcl2 cells, which were generated by transfecting SC-M1 cells with bcl-2 DNA, were growth-arrested two days earlier than SC-M1/neo cells, which were generated by transfecting SC-M1 cells with vector DNA. This indicates that Bcl-2 accelerates RA-induced growth arrest. In addition to the accelerated growth arrest, RA-treated SC-M1/Bcl2 cells also recovered from growth arrest two days faster than SC-M1/neo cells after the removal of RA. Previously, we had identified the cyclin-dependent kinase inhibitor p21((WAF1/CIP1)) (p21) as a mediator of RA-induced growth arrest [Tsao, Li, Kuo, Liu and Chen (1996) Biochem. J. 317, 707-711]. In a search for the mechanism by which Bcl-2 affects growth regulation, we found that p21 gene expression was more prominent in SC-M1/Bcl2 cells than in SC-M1/neo cells in the presence of RA, but when RA was removed, p21 gene expression levels in SC-M1/Bcl2 cells were also reduced earlier than in SC-M1/neo cells. The present report is the first to show that Bcl-2 accelerates not only growth arrest but also recovery from growth arrest. Moreover, the close correlation between the effect of Bcl-2 on both RA-induced growth arrest and RA-induced p21 gene expression suggests the possibility that Bcl-2 affects cell growth through the mechanism of p21.
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PMID:Bcl-2 accelerates retinoic acid-induced growth arrest and recovery in human gastric cancer cells. 1081 44

Gentamicin, an aminoglycoside antibiotic, induces apoptosis in the proximal tubule epithelium of rats treated at low, therapeutically relevant doses (El Mouedden et al., Antimicrob. Agents Chemother. 44, 665-675, 2000). Renal cell lines (LLC-PK(1) and MDCK-cells) have been used to further characterize and quantitate this process (electron microscopy; terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling of fragmented DNA [TUNEL]; and DNA size analysis [oligonucleosomal laddering]). Cells were exposed for up to 4 days to gentamicin concentrations of up to 3 mM. Apoptosis developed, almost linearly, with time and drug concentration, and was (i) preventable within the time-frame of the experiments by overexpression of the anti-apoptotic protein Bcl-2, and by co-incubation with cycloheximide (MDKC but not LLC-PK(1) cells); (ii) associated with an increased activity of caspases (MDCK cells; bcl-2 transfectants showed no increase of caspase activities and Z-VAD.fmk afforded full protection). Gentamicin-induced apoptosis also developed to a similar extent in embryonic fibroblasts cultured under the same conditions. In the 3 cell types, apoptosis (measured after 4 days) was directly correlated with cell gentamicin content (apoptotic index [approximately 10 to 18% of TUNEL (+) cells for a content of 20 microg of gentamicin/mg protein; kidney cortex of rats showing apoptosis in proximal tubule epithelium typically contains approximately 10 microg of gentamicin/mg protein). Thus, gentamicin has an intrinsic capability of inducing apoptosis in eucaryotic cells. Development of apoptosis in proximal tubules of kidney cortex in vivo after gentamicin systemic administration is therefore probably related to its capacity to concentrate in this epithelium after systemic administration.
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PMID:Gentamicin-induced apoptosis in renal cell lines and embryonic rat fibroblasts. 1086 72

Bcl-2, an anti-apoptotic protein, is believed to be localized in the outer mitochondrial membrane, endoplasmic reticulum, and nuclear envelope. However, Bcl-2 has also been suggested as playing a role in the maintenance of mitochondrial membrane potential, indicating its possible association with the inner mitochondrial membrane. We therefore further examined the exact localization of Bcl-2 in mitochondria purified from wild-type and bcl-2-transfected PC12 cells and pre- and postnatal rat brains. Double immunostaining demonstrated that Bcl-2 was co-localized with subunit beta of F1F0ATPase in the inner mitochondrial membrane. Biochemical analysis of isolated mitochondria using digitonin and trypsin suggests an association of Bcl-2 with the inner mitochondrial membrane. More interestingly, the majority of Bcl-2 disappeared from the inner membrane of mitochondria when cultured under serum deprivation. These results suggest that Bcl-2 acts as an anti-apoptotic regulator by localizing mainly to the inner mitochondrial and smooth ER membranes.
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PMID:Selective localization of Bcl-2 to the inner mitochondrial and smooth endoplasmic reticulum membranes in mammalian cells. 1088 11

Dopaminergic neurons in the substantia nigra pars compacta (SNpc) undergo natural cell death during development in rats. Controversy exists as to the occurrence of this phenomenon in SNpc dopaminergic neurons in the developing mouse. Herein, by using an array of morphologic techniques, we show that many SNpc neurons fulfill the criteria for apoptosis and that the number of apoptotic neurons in the SNpc vary in a time-dependent manner from postnatal day 2 to 32. These dying neurons also show evidence of DNA fragmentation, of activated caspase-3, and of cleavage of beta-actin. Some, but not all of the SNpc apoptotic neurons still express their phenotypic marker tyrosine hydroxylase, confirming their dopaminergic nature. Consistent with the importance of target-derived trophic support in modulating developmental cell death, we demonstrate that destruction of intrinsic striatal neurons by a local injection of quinolinic acid (QA) dramatically enhances the magnitude of SNpc apoptosis and results in a lower number of adult SNpc dopaminergic neurons. Strengthening the apoptotic nature of the observed SNpc developmental cell death, we demonstrate that overexpression of the anti-apoptotic protein Bcl-2 attenuates both natural and QA-induced SNpc apoptosis. The present study provides compelling evidence that developmental neuronal death with a morphology of apoptosis does occur in the SNpc of mice and that this process plays a critical role in regulating the adult number of dopaminergic neurons in the SNpc.
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PMID:Developmental cell death in dopaminergic neurons of the substantia nigra of mice. 1090 14

Immunity against mycobacteria is almost exclusively confined to epithelioid cell granulomas, where a long-lasting but labile balance exists between host and bacilli. The relationship between immunity and mycobacteria results in regression, growth, or caseation of granulomas. To prove whether caseation is associated with apoptosis, biopsy specimens of patients with tuberculosis were analysed by electron microscopy and by in situ end-labelling combined with immunofluorescence. Apoptotic cells were not detected in regressive granulomas. Whereas productive granulomas without histologically recognizable caseous necrosis revealed only single apoptotic cells, large numbers of apoptotic CD68+ macrophages and apoptotic CD3+, CD45RO+ T cells were observed within caseous foci. As prime candidates undergoing and/or eliciting apoptosis, vital cells surrounding caseous foci were characterized. Immunohistochemistry showed that the majority of vital CD68+ macrophages surrounding caseous foci are negative for the anti-apoptotic protein bcl2, but positive for the pro-apoptotic protein bax. In situ hybridization combined with immunofluorescence demonstrated that the majority of the adjacent lymphocytes are activated CD3+, CD45RO+ cells expressing the pro-inflammatory cytokine interferon gamma (IFN gamma) and the death ligand FasL. These results suggest that caseation is strongly associated with apoptosis of macrophages and T lymphocytes; that the onset of apoptosis in macrophages may be promoted by the lack of bcl2 and the abundance of bax; and that activation-induced cell death (AICD) may be responsible for the apoptosis of T cells.
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PMID:Apoptosis of macrophages and T cells in tuberculosis associated caseous necrosis. 1091 17

Despite the capacity for antigen-specific activation and rapid clonal expansion, homeostatic mechanisms ensure that the mature immune system contains a relatively stable number of T cells. In recent years, it has become apparent that this stability is a consequence of apoptotic death of most of the specific T cells generated during an immune response. Clearly this process must be tightly regulated in order to retain sufficient T-cell progeny to mediate an effective response, whilst allowing the rapid deletion of these cells at the end of the response to prevent lymphadenopathy and cross-reactive autoimmunity. In this study, the factors that regulate the sensitivity of T cells to apoptosis were investigated in vitro after the induction of primary T-cell activation within a mixed lymphocyte reaction (MLR). It was found that activated T cells rapidly acquire the expression of both Fas and Fas ligand (FasL) on their surface and contain high levels of the precursor form of the pro-apoptotic enzyme, caspase 8 (FLICE). However, these T cells were resistant for up to 5 days to apoptosis following the stimulation of Fas; a maximal apoptotic response was observed after 7 days. This time point coincided with a marked reduction in expression of the FLICE inhibitory protein (FLIP) and maximal activity of caspase 8. At time points beyond day 7, the number of viable cells in the MLR decreased further despite a reduction in the expression of FasL. However, the expression of interleukin-2 (IL-2) at these late time points was low, resulting in a decrease in expression of the anti-apoptotic protein Bcl-2. This can produce apoptosis by allowing leakage of cytochrome-c from mitochondria resulting in direct activation of the caspase cascade. In this study, it is shown that T cells are resistant to apoptosis for the first 5 days after activation as a consequence of insensitivity of the Fas pathway and the presence of intracellular Bcl-2. After between 5 and 7 days, the cells become sensitive to Fas-mediated apoptosis while retaining Bcl-2 expression. At later time points, Fas ligation is reduced but the cells respond to a decreased availability of IL-2 by reducing Bcl-2 expression; this encourages further apoptosis by allowing the direct activation of caspase enzymes.
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PMID:Regulation of T-cell apoptosis: a mixed lymphocyte reaction model. 1092 50

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