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)

Recent studies on cells derived from mice deficient in both multi-domain pro-apoptotic genes of the Bcl-2 family, Bax and Bak, suggest that one or other of these proteins are required for the release of apoptogens such as cytochrome c from mitochondria. In addition BH-3 only proteins of this family such as Bid are suggested to act as critical death inducing ligands via interactions with pro- and anti-apoptotic Bcl-2 family proteins with Bax or Bak at the mitochondrial surface. Despite this increase in knowledge it remains unclear precisely how Bak and Bax promote outer mitochondrial membrane (OMM) permeabilisation. We suggest that Bax and Bak may not operate in precisely the same manner and evaluate the current models for their function. We also consider the emerging information that lipid-protein interactions may be crucial to the actions of Bax and Bak.
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PMID:Mitochondrial membrane permeabilisation by Bax/Bak. 1272 79

Although the mechanisms that underlie cardiac cell death remain cryptic, there is emerging evidence that mitochondria may play a pivotal role in this process. The mitochondrion initially deemed the "power house " is now considered to be a central integration site for biological signals that promote cell life or cell death. Since mitochondria contain the necessary apoptotic machinery to activate the cell-death pathway, it is now appreciated that mitochondria play a key decision-making role in whether a cell will live or die following a noxious signal-literally a "license to kill ". Permeability changes to the outer mitochondrial membrane, collapse of membrane potential, permeability pore complex assembly, release of cytotoxic proteins and caspase activation are associated with the mitochondrial-death pathway. Members of the Bcl-2 gene family can promote or suppress cell death by modulating mitochondrial function. Activation of the mitochondrial-death pathway has been reported in several cardiac pathologies and believed to account for the reported apoptosis observed in these disease entities. Given the meager and limited ability of cardiac muscle for repair or self-renewal after injury, the inordinate loss of cardiac cells is considered to be a key underlying factor in ventricular remodeling and decline in ventricular performance in patients with ischemic heart disease or post-myocardial infarction. This review will provide mechanistic insight into the involvement and contribution of the mitochondrion as a regulator of cell death in health and disease with particular focus on the heart.
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PMID:Mitochondria-assisted cell suicide: a license to kill. 1278 72

Apoptosis is a regulated cell death program controlled by extrinsic and intrinsic signaling pathways. The intrinsic pathway involves stress signals that activate pro-apoptotic members of the Bcl-2 family, inducing permeabilization of mitochondria and release of apoptogenic factors. These proteins localize to the outer mitochondrial membrane. Ian4, a mitochondrial outer membrane protein with GTP-binding activity, is normally present in thymocytes, T cells, and B cells. We and others have recently discovered that a mutation in the rat Ian4 gene results in severe T cell lymphopenia that is associated with the expression of autoimmune diabetes. The mechanism by which Ian4 controls T cell homeostasis is unknown. Here we show that the absence of Ian4 in T cells causes mitochondrial dysfunction, increased mitochondrial levels of stress-inducible chaperonins and a leucine-rich protein, and T cell-specific spontaneous apoptosis. T cell activation and caspase 8 inhibition both prevented apoptosis, whereas transfection of T cells with Ian4-specific small interfering RNA recapitulated the apoptotic phenotype. The findings establish Ian4 as a tissue-specific regulator of mitochondrial integrity.
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PMID:Ian4 is required for mitochondrial integrity and T cell survival. 1293 Aug 93

Mitochondria play a central role in apoptosis triggered by many stimuli. They integrate death signals through Bcl-2 family members and co-ordinate caspase activation through the release of apoptogenic factors that are normally sequestered in the mitochondrial intermembrane space. The release of these proteins is the result of the outer mitochondrial membrane becoming permeable. In addition, mitochondria can initiate apoptosis through the production of reactive oxygen species.
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PMID:Apoptosis: bombarding the mitochondria. 1458 73

Mitochondria are central to many forms of cell death, usually via the release of pro-apoptotic proteins from the mitochondrial intermembrane space. Some intermembrane space proteins, including cytochrome c, Smac/DIABLO, and Omi/Htra2, can induce or enhance caspase activation, whereas others, such as AIF and endonuclease G, might act in a caspase-independent manner. Intermembrane space protein release is often regulated by Bcl-2-family proteins. Recent evidence suggests that pro-apoptotic members of this family, by themselves, can permeabilize the outer mitochondrial membrane without otherwise damaging mitochondria. Mitochondria can contribute to cell death in other ways. For example, they can respond to calcium release from the endoplasmic reticulum by undergoing the mitochondrial permeability transition, which in turn causes outer membrane rupture and the release of intermembrane space proteins. Bcl-2-family proteins can influence the levels of releasable Ca(2+) in the endoplasmic reticulum, and thus determine whether the released Ca(2+) is sufficient to overload mitochondria and induce cell death.
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PMID:Bcl-2-family proteins and the role of mitochondria in apoptosis. 1464 93

Glucocorticoids (GC) control cell cycle progression and induce apoptosis in cells of the lymphoid lineage. Physiologically, these phenomena have been implicated in regulating immune functions and repertoire generation. Clinically, they form the basis of inclusion of GC in essentially all chemotherapy protocols for lymphoid malignancies. In spite of their significance, the molecular mechanisms underlying the anti-leukemic GC effects and the clinically important phenomenon of GC resistance are still unknown. This review summarizes recent findings related to GC-induced apoptosis, cell cycle arrest, and GC resistance with particular emphasis on acute lymphoblastic leukemia (ALL). We hypothesize that under conditions of physiological Bcl-2 expression, GC might induce classical programmed cell death by directly perturbing the Bcl-2 rheostat. In the presence of anti-apoptotic Bcl-2 proteins, cell death might result from accumulating catabolic and/or other detrimental GC effects driven by, and critically dependent on, GC receptor (GR) autoinduction. Although still controversial, there is increasing evidence for release of apoptogenic factors through pores in the outer mitochondrial membrane, rather than deltapsiloss-dependent membrane rupture, with maintenance of mitochondrial function at least in the early phase of the death response. GC-induced cell cycle arrest in ALL cells appears to be independent of apoptosis induction and vice versa, and critically depends on repression of both cyclin-D3 and c-myc followed by increased expression of the cyclin-dependent kinase inhibitor, p27Kip1. Since development of GC-resistant clones requires both cell cycle progression and survival, GC resistance might frequently result from structural or regulatory defects in GR expression, perhaps the most efficient means to target both pathways concurrently.
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PMID:A conceptual view on glucocorticoid-lnduced apoptosis, cell cycle arrest and glucocorticoid resistance in lymphoblastic leukemia. 1468 92

Two main intracellular apoptosis cascades, the receptor and the mitochondria pathway, have been identified. The mitochondrial pathway is controlled by the Bcl-2 proteins. This protein family contains members with either pro- or anti-apoptotic activity. When activated the pro-apoptotic multidomain proteins permeabilized the outer mitochondrial membrane, resulting in the release of proteins from the intermembrane space. Several proteins, including cytochrome c, Smac/DIABLO, HtrA2/Omi, endonuclease G and AIF, normally sequestered in the mitochondria induce or promote apoptosis once released into the cytosol. Although, apoptosis is an essential physiological process in multicellular organisms it is also involved in a wide range of pathological conditions.
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PMID:Mitochondria and the Bcl-2 family proteins in apoptosis signaling pathways. 1497 77

Recent studies have suggested that in the absence of Bid, granzyme B (GrB) can utilize an unknown alternative pathway to mediate mitochondrial apoptotic events. The current study has elucidated just such a pathway for GrB-mediated mitochondrial apoptotic alterations. Two Bcl-2 family members have been identified as interactive players in this newly discovered mitochondrial response to GrB: the pro-survival protein Mcl-1L and the pro-apoptotic protein, Bim. Expression of Mcl-1L, which localizes mainly to the outer mitochondrial membrane, decreases significantly in cells subjected to CTL-free cytotoxicity mediated by a combination of GrB and replication-deficient adenovirus. The data suggest that Mcl-1L is a substrate for GrB and for caspase-3, but the two enzymes appear to target different cleavage sites. The cleavage pattern of endogenous Mcl-1L resembles that of in vitro translated Mcl-1L subjected to similar proteolytic activity. Co-immunoprecipitation experiments performed with endogenous as well as with in vitro translated proteins suggest that Mcl-1L is a high affinity binding partner of the three isoforms of Bim (extra-long, long, and short). Bim, a BH3-only protein, is capable of mediating the release of mitochondrial cytochrome c, and this activity is inhibited by the presence of exogenous Mcl-1L. The findings presented herein imply that Mcl-1L degradation by either GrB or caspase-3 interferes with Bim sequestration by Mcl-1L.
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PMID:Degradation of Mcl-1 by granzyme B: implications for Bim-mediated mitochondrial apoptotic events. 1501 70

A plethora of apoptotic stimuli converge on the mitochondria and affect their membrane integrity. As a consequence, multiple death-promoting factors residing in the mitochondrial intermembrane space are liberated in the cytosol. Pro- and antiapoptotic Bcl-2 family proteins control the release of these mitochondrial proteins by inducing or preventing permeabilization of the outer mitochondrial membrane. Once released into the cytosol, these mitochondrial proteins activate both caspase-dependent and -independent cell death pathways. Cytochrome c was the first protein shown to be released from the mitochondria into the cytosol, where it induces apoptosome formation. Other released mitochondrial proteins include apoptosis-inducing factor (AIF) and endonuclease G, both of which contribute to apoptotic nuclear DNA damage in a caspase-independent way. Other examples are Smac/DIABLO (second mitochondria-derived activator of caspase/direct IAP-binding protein with low PI) and the serine protease HtrA2/OMI (high-temperature requirement protein A2), which both promote caspase activation and instigate caspase-independent cytotoxicity. The precise mode of action and importance of cytochrome c in apoptosis in mammalian cells has become clear through biochemical, structural and genetic studies. More recently identified factors, for example HtrA2/OMI and Smac/DIABLO, are still being studied intensively in order to delineate their functions in apoptosis. A better understanding of these functions may help to develop new strategies to treat cancer.
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PMID:Toxic proteins released from mitochondria in cell death. 1507 49

Although it has long been known that impairment of mitochondrial function may lead to ATP depletion and necrotic cell death, recent work has revealed that these organelles also play an important role in the regulation of apoptotic cell death by mechanisms which have been conserved through evolution. Thus, it seems that a number of toxicants target the mitochondria and promote their release of cytochrome c and other pro-apoptotic proteins, which can trigger caspase activation and other parts of the apoptotic process. Cytochrome c release is governed by the Bcl-2 family of proteins, whereas subsequent caspase activation is modulated by other proteins, including inhibitor of apoptosis proteins (IAPs) and heat shock proteins. Recent findings indicate that cytochrome c extrusion occurs by a two-step process, which is initiated by a disruption of the association of the hemoprotein with cardiolipin, the phospholipid that anchors it to the outer surface of the inner mitochondrial membrane. Release of the solubilized pool of cytochrome c into the cytosol may then occur by permeabilization of the outer mitochondrial membrane mediated by pro-apoptotic Bcl-2 family proteins, notably Bax and Bak, or by Ca2+-triggered mitochondrial permeability transition. Taken together, these findings have placed the mitochondria in the focus of apoptosis research and further underlined the important function of these organelles in cell life and death.
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PMID:Mitochondrial regulation of apoptotic cell death. 1509 44


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