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)

Cellular Bcl-2 family proteins regulate a critical step in the mammalian programmed cell death pathway by modulating mitochondrial permeability and function. Bcl-2 family proteins are also encoded by several large DNA viruses, including all known gamma herpesviruses, adenoviruses, and several other unrelated viruses. Viral Bcl-2 proteins can prevent cell death but often escape cellular regulatory mechanisms that govern their cellular counterparts. By evading the "altruistic" suicide of infected cells, viruses can ensure replication and propagation in the infected host, but sometimes in surprising ways. Many human cancers and other disorders are associated with viruses that encode Bcl-2 homologs. Here we consider the available mechanistic data for viral compared to cellular Bcl-2 protein function along with relevance to the virus life cycle and human disease states.
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PMID:Viral Bcl-2 homologs and their role in virus replication and associated diseases. 1499 5

In a variety of physiological settings, cells are eliminated by apoptosis-a genetically encoded process of cellular suicide. Bak, a member of the Bcl-2 protein family, accelerates apoptosis by an unknown mechanism. We have found a novel cDNA encoding a 101-amino acid protein that possesses a Bak-like sequence in our full-length cDNA bank and termed it Bak-like. This protein shares the conserved domains BH1 and BH2 with other pro-apoptotic proteins, but lacks the BH3 domain. Database searches identified this gene on chromosome 6, which could account for the cloned bak and bak-like transcripts by alternative splicing. Bak-like is expressed in a wide variety of tissues. Bak-like is different from bak by Southern blots using probes with or without homology to bak. Despite the loss of the BH3 sequence, bak-like did enhance apoptosis, but was less potent than bak. Confocal microscopy of HeLa cells revealed that EGFP-Bak-like was located diffusely throughout the cytosol. However, upon induction of apoptosis, EGFP-Bak-like redistributed into a punctuate pattern, colocalizing with mitochondria. Like bak, the bak-like gene product directly enhanced apoptotic cell death following an appropriate stimulus.
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PMID:Enhanced apoptosis by a novel gene, Bak-like, that lacks the BH3 domain. 1500 5

Mechanosensory hair cells of the inner ear are especially sensitive to death induced by exposure to aminoglycoside antibiotics. This aminoglycoside-induced hair cell death involves activation of an intrinsic program of cellular suicide. Aminoglycoside-induced hair cell death can be prevented by broad-spectrum inhibition of caspases, a family of proteases that mediate apoptotic and programmed cell death in a wide variety of systems. More specifically, aminoglycoside-induced hair cell death requires activation of caspase-9. Caspase-9 activation requires release of mitochondrial cytochrome c into the cytoplasm, indicating that aminoglycoside-induced hair cell death is mediated by the mitochondrial (or "intrinsic") cell death pathway. The Bcl-2 family of pro-apoptotic and anti-apoptotic proteins are important upstream regulators of the mitochondrial apoptotic pathway. Bcl-2 is an anti-apoptotic protein that localizes to the mitochondria and promotes cell survival by preventing cytochrome c release. Here we have utilized transgenic mice that overexpress Bcl-2 to examine the role of Bcl-2 in neomycin-induced hair cell death. Overexpression of Bcl-2 significantly increased hair cell survival following neomycin exposure in organotypic cultures of the adult mouse utricle. Furthermore, Bcl-2 overexpression prevented neomycin-induced activation of caspase-9 in hair cells. These results suggest that the expression level of Bcl-2 has important effects on the pathway(s) important for the regulation of aminoglycoside-induced hair cell death.
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PMID:Overexpression of Bcl-2 prevents neomycin-induced hair cell death and caspase-9 activation in the adult mouse utricle in vitro. 1518 75

In HeLa cells, complete inhibition of oxidative phosphorylation by oligomycin, myxothiazol or FCCP combined with partial inhibition of glycolysis by DOG resulted in a steady threefold decrease in the intracellular ATP level. The ATP level recovers when the DOG-containing medium was replaced by that with high glucose. In 48 h after a transient (3 h) [ATP] lowering followed by recovery of the ATP level, the majority of the cells commits suicide by means of apoptosis. The cell death does not occur if DOG or an oxidative phosphorylation inhibitor was added separately, treatments resulting in 10-35% lowering of [ATP]. Apoptosis is accompanied by Bax translocation to mitochondria, cytochrome c release into cytosol, caspase activation, reactive oxygen species (ROS) generation, and reorganization and decomposition of chromatin. Apoptosis appears to be sensitive to oncoprotein Bcl-2 and a pancaspase inhibitor zVADfmk. In the latter case, necrosis is shown to develop instead of apoptosis. The cell suicide is resistant to cyclosporine A, a phospholipase inhibitor trifluoroperazine, the JNK and p38 kinase inhibitors, oligomycin, N-acetyl cysteine and mitoQ, differing in these respects from the tumor necrosis factor (TNF)- and H(2)O(2)-induced apoptoses. It is suggested that the ATP concentration in the cell is monitored by intracellular "ATP-meter(s)" generating a cell suicide signal when ATP decreases, even temporarily, below some critical level (around 1 mM).
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PMID:"Wages of fear": transient threefold decrease in intracellular ATP level imposes apoptosis. 1528 85

In replicative senescence, cells undergo permanent exit from cell cycle traverse; this is traditionally thought to occur at the end of a culture's in vitro life span, after serial passaging. In general, the checkpoint for replicative senescence is found at the G(1)/S border, controlled by the modulation of a battery of proteins, typified by gaining inhibitors of cell cycle traverse, such as cyclin-dependent kinases or RB hyperphosphorylation, and losing pro-proliferation gene expressions such as c-fos, c-myc, and a cadre of proliferation-dependent kinases. Here, we present evidence that replicatively senescent fibroblasts are resistant to apoptotic death, associated with a lack of key enzyme activities, caspase-3 being the chief executioner. This observation, coupled with our earlier report that senescent fibroblasts maintain persistently high levels of pro-survival factor Bcl-2, suggests that the molecular signaling program present in fibroblasts at the end of their in vitro life span may not only cater to the state of permanent exit from cell cycle traverse, but also dictate an inability to commit cellular suicide. Future experiments will reveal whether replicatively senescent fibroblasts that can neither proliferate nor die contribute to organismic aging, and whether their accumulation over time in tissue becomes detrimental to the normal aging process.
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PMID:Senescent fibroblasts resist apoptosis by downregulating caspase-3. 1554 72

Herpesvirus tegument protein VP22 has been shown to have biotherapeutic potential in tumor gene therapy. Some studies indicate that VP22 may enhance the transfer efficiency of therapeutic proteins by delivering them to more cells while trafficking. Our previous study showed that bovine herpesvirus VP22 (BVP22) enhanced equine herpesvirus thymidine kinase-ganciclovir (Etk-GCV) suicide gene therapy by an unknown intracellular effect. In this study, the interaction between BVP22 and host tumor cells was studied in neuroblastoma NXS2 cells. Cell cycle analysis was performed to determine whether BVP22 possesses biotherapeutic potential by altering the cell cycle, making cells more sensitive to therapeutic genes. As a result, the cell cycle was not affected by the transfection of BVP22 into NXS2 cells. However, cytotoxicity induced by BVP22 was observed in NXS2 cells on the second and third days after transient transfection. Further, analyses of caspase-3 activity and apoptosis suggested that BVP22 induces apoptosis in host tumor cells by upregulating the expression ratio of Bax to Bcl-2.
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PMID:Bovine herpesvirus VP22 induces apoptosis in neuroblastoma cells by upregulating the expression ratio of Bax to Bcl-2. 1570 93

Apoptosis is an important cell suicide programme involved in physiological and pathological processes. Apoptosis can be induced in different ways depending on cell type and acquired signal. Melatonin, the major secretory product of the pineal gland, participates in many important physiological functions and displays a remarkable functional versatility exhibiting antioxidant, oncostatic, anti-aging, and immunomodulatory properties. Recently, it has been shown that, in addition to pineal gland, human lymphoid cells are an important physiological source of melatonin and that may be involved in the regulation of the immune system. In this work, we examine the effect of melatonin on RAMOS-1 human leukaemic cells. Cell growth and viability, DNA fragmentation and JC-1, and annexin V expression have been determined. To elucidate the mechanism of action of melatonin, Western blot analyses for Bcl-2 and caspase-3 expression, and cytochrome c release were carried out. The results suggest that the apoptotic effect of melatonin is associated with cell-cycle arrest, downregulation of Bcl-2, mitochondrial membrane depolarization, cytochrome c release and activation of caspase-3. The intrinsic (mitochondrial dependent) pathway of caspase activation is the 'point of no return' commitment to cell death. Taken together, our study indicates that melatonin may play a role as potential therapeutic drug in specific lymphoproliferative diseases.
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PMID:Melatonin provokes cell death in human B-lymphoma cells by mitochondrial-dependent apoptotic pathway activation. 1620 99

Apoptosis is an inducible suicide program that occurs in all phases of multicellular as well as in protozoa life and gains more and more importance in all medical disciplines. It is required for normal ontogenesis, organ and tissue remodeling, function of the immune system, prevention of inappropriate cellular proliferation and of survival of inappropriate mutations. Thereby apoptosis represents the key event which guarantees differentiation and maintenance of homeostasis. Terminal differentiation seems to be a special form of apoptosis. Dysregulated apoptosis is associated with various pathological conditions, including inflammation, and cancer. Acanthosis, the hallmark of psoriatic skin, is an example for diminished epidermal apoptosis. Defects in termination of inflammatory reactions occur in atopic dermatitis. Lupus erythematosus may arise due to disturbed apoptosis on several check points of the apoptosis cascade. Experimental evidence suggests a role for Bcl-2 and CD95L in the inhibition of programmed cell death in UV-induced skin cancer or malignant melanoma cells. Thus, it leads to survival of malignant cell clones. The slow growth of basal cell carcinomas is due to an increased apoptosis to mitosis ratio. Spontaneous regression of tumors is associated with increased apoptotic rates. Malignant melanoma cells characteristically show different anti-apoptotic strategies which underscore its aggressive behavior and its refractory towards classic therapeutic regimens. Additionally, induction of apoptosis in tumor infiltrating immune cells seems to be a strategy by which the tumor escapes from an immunological attack (tumor counter-attack). Since apoptosis is either absent or altered under pathological conditions therapeutic procedures should correct this. Established therapies like dithranol, vitanin-D3 analogs, low-dose methotrexate, induce apoptosis. Future treatment regimens like vaccine and gene therapy are designed to selectively induce apoptosis. Therefore, pharmacological agents and therapeutic strategies interfering with disrupted apoptosis regulation could improve the therapeutic arsenal in the future.
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PMID:Apoptosis in physiological and pathological skin: implications for therapy. 1690 Jun 61

Apoptosis, or programmed cell death (PCD), involves a complex network of biochemical pathways that normally ensure a homeostatic balance between cellular proliferation and turnover in nearly all tissues. Apoptosis is essential for the body, as its deregulation can lead to several diseases. It plays a major role in a variety of physiological events, including embryonic development, tissue renewal, hormone-induced tissue atrophy, removal of inflammatory cells, and the evolution of granulation tissue into scar tissue. It also has an essential role in wound repair. The various cellular and biochemical mechanisms involved in apoptosis are not fully understood. However, there are two major pathways, the extrinsic pathway (receptor-mediated apoptotic pathway) and the intrinsic pathway (mitochondria-mediated apoptotic pathway), which are both well established. The key component in both is the activation of the caspase cascade. Caspases belong to the family of proteases that ultimately, by cleaving a set of proteins, cause disassembly of the cell. Although the caspase-mediated proteolytic cascade represents a central point in the apoptotic response, its initiation is tightly regulated by a variety of other factors. Among them, Bcl-2 family proteins, TNF and p53 play pivotal roles in the regulation of caspase activation and in the regulation of apoptosis. This review summarizes the established concepts in apoptosis as a physiological cell suicide program, highlighting the recent and significant advances in its study.
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PMID:Current concepts in apoptosis: the physiological suicide program revisited. 1697 76

Apoptosis is a process of cell suicide, the mechanisms of which are encoded in the chromosomes of all nucleated cells. Apoptosis occurs spontaneously throughout mammalian spermatogenesis for the development of normal mature spermatozoa and for the elimination of excess or abnormal germ cells: a critical prerequisite for functional spermatogenesis under physiological conditions. Any deregulation of the apoptotic process during spermatogenesis would lead to defective sperm formation and while increased apoptosis could potentially lead to infertility, decreased cell death could do the same by disrupting testicular homeostasis due to accumulation of cells. Male germ cell apoptosis occurs through two major pathways, involving either mitochondria (intrinsic) or cell surface death receptors (extrinsic). The mitochondrial pathway of apoptosis involves the Bcl-2 group of proteins and different members of this group are involved in diverse situations. The cell death receptor pathway involves members of the TNF receptor superfamily. The stimuli for germ cell apoptosis are internal cues that control proper homeostasis of the testicular tissue or external agents including testicular toxins, heat stress and chemotherapeutic agents. In addition, an imbalance of hormones can lead to the apoptosis of germ cells. The pathway of apoptosis adopted by the germ cells depends on the type of stimuli they receive. This review discusses the recent advances made in the understanding of the mechanisms of germ cell apoptosis that may provide clues to the control of male fertility or treating germ cell tumors and other testis associated pathological conditions.
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PMID:Modulators of spermatogenic cell survival. 1756 72


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