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Pro-apoptotic Member (pro-apoptotic + member)
Selected AbstractsInteraction of the alpha-helical H6 peptide from the pro-apoptotic protein tBid with cardiolipinFEBS JOURNAL, Issue 21 2009Patrice X. Petit BH3 interacting domain death agonist (Bid), a pro-apoptotic member of the Bcl-2 family of proteins, is activated through cleavage by caspase-8. The active C-terminal fragment of Bid (tBid) translocates to the mitochondria where it interacts with cardiolipins at contact sites and induces the release of cytochrome c by a mechanism that is not yet fully understood. It has been shown that the alpha-helices ,H6 and ,H7 (which create the hairpin-forming domain of tBid) mediate the insertion of Bid into mitochondrial membranes and are essential for the cytochrome c -releasing activity. In the present study, we focused on the interaction between the ,H6 and the mitochondrial membrane. By the use of single-cell electropermeabilization associated with flow cytometric analysis of intact cells, we demonstrated that H6 is able to induce cell death when used in the micromolar range. We also studied the interactions of the ,H6 with artificial monolayers. We showed that the presence of negatively charged cardiolipins greatly enhances the insertion of ,H6 into the phospholipid monolayer. The modification of two charged amino acid residues in ,H6 abolished its insertion and also its in vivo effects. Furthermore, the negative values of the excess areas of mixing indicate that attractive interactions between cardiolipins and ,H6 occur in the mixed monolayers. Fluorescence microscopy observations revealed that ,H6 significantly disrupts cardiolipin packing and stabilizes the fluid lipid phase. These results suggest that cardiolipins at the contact sites between the two mitochondrial membranes could mediate the binding of tBid via ,H6. [source] The Bcl-2 family pro-apoptotic molecule, BNIP3 regulates activation-induced cell death of effector cytotoxic T lymphocytesIMMUNOLOGY, Issue 1 2003J. Wan Summary BNIP3 is a recently described pro-apoptotic member of the Bcl-2 family and in BNIP3 cDNA-transfected cell lines, cell death occurs via a caspase-independent pathway with opening of the mitochondrial permeability transition (PT) pore and rapid loss of mitochondrial transmembrane potential (,,m). However, its expression or function in physiologic cell types is not known. Our results using the T-cell receptor transgenic mice P14, specific for lymphocyte choreomeningitis virus (LCMV) glycoprotein, show that in contrast to the other Bcl-2 family pro-apoptotic molecules, BNIP3 is transcriptionally highly up-regulated in effector cytotoxic T lymphocytes (CTL). Because CTL have a propensity to undergo activation-induced cell death (AICD) upon restimulation, we tested for other features associated with BNIP3-induced cell death. AICD of CTL was caspase-independent as determined by measuring caspase activation during target cell killing as well as by lack of inhibition with caspase inhibitors. Moreover, similar to BNIP3-induced cell death, CTL apoptosis was associated with increased production of reactive oxygen species and decreased ,,m. Finally, retroviral transduction of BNIP3 antisense RNA diminished AICD in effector CTL. These results suggest that BNIP3 may play an important role in T-cell homeostasis by regulating effector CTL numbers. [source] Mutational and expressional analysis of BNIP3, a pro-apoptotic Bcl-2 member, in gastric carcinomas,APMIS, Issue 11 2007SUNG HAK LEE Cell death deregulation is a hallmark of human cancers. BNIP3 was initially identified as a pro-apoptotic member of the Bcl-2 family and plays an important role in apoptosis, necrosis and autophagy. The aim of this study was to see whether alterations of BNIP3 protein expression and somatic mutation of the BNIP3 gene are characteristics of human cancers. We analyzed the expression of BNIP3 protein in 60 gastric adenocarcinomas by immunohistochemistry. In addition, we analyzed BNIP3 mutation in the DNA sequences encoding BH3 (Bcl-2 homology3) and TM (transmembrane) domains that are important in the cell death function of BNIP3 by single-strand conformation polymorphism (SSCP) in 48 colorectal, 48 gastric, and 48 breast carcinomas, and 48 acute leukemias. By immunohistochemistry, BNIP3 protein was detected in 40 of the 60 carcinomas (67%). Both early and advanced gastric carcinomas expressed BNIP3. There was no significant association between BNIP3 expression and clinicopathologic characteristics, including invasion, metastasis and stage. In contrast to the cancer cells, epithelial cells in normal gastric mucosa showed no or weak expression of BNIP3. Mutational analysis revealed BNIP3 mutation in neither the BH3 nor the TM domain, suggesting that BNIP3 mutation in these domains is not a direct target of inactivation in gastric, colorectal and breast carcinomas, and acute leukemias. Increased expression of BNIP3 in the malignant gastric epithelial cells compared to the normal mucosal epithelial cells suggests that BNIP3 expression might play a role in gastric carcinoma development. [source] Induction of apoptosis in monocytes by Mycobacterium leprae in vitro: a possible role for tumour necrosis factor-,IMMUNOLOGY, Issue 1 2003M. O. Hernandez Summary A diverse range of infectious organisms, including mycobacteria, have been reported to induce cell death in vivo and in vitro. Although morphological features of apoptosis have been identified in leprosy lesions, it has not yet been determined whether Mycobacterium leprae modulates programmed cell death. For that purpose, peripheral blood mononuclear cells obtained from leprosy patients were stimulated with different concentrations of this pathogen. Following analysis by flow cytometry on 7AAD/CD14+ cells, it was observed that M. leprae induced apoptosis of monocyte-derived macrophages in a dose-dependent manner in both leprosy patients and healthy individuals, but still with lower efficiency as compared to M. tuberculosis. Expression of tumour necrosis factor-, (TNF-,), Bax-,, Bak mRNA and TNF-, protein was also detected in these cultures; in addition, an enhancement in the rate of apoptotic cells (and of TNF-, release) was noted when interferon-, was added to the wells. On the other hand, incubation of the cells with pentoxifylline impaired mycobacterium-induced cell death, the secretion of TNF-,, and gene expression in vitro. In addition, diminished bacterial entry decreased both TNF-, levels and the death of CD14+ cells, albeit to a different extent. When investigating leprosy reactions, an enhanced rate of spontaneous apoptosis was detected as compared to the unreactive lepromatous patients. The results demonstrated that M. leprae can lead to apoptosis of macrophages through a mechanism that could be at least partially related to the expression of pro-apoptotic members of the Bcl-2 protein family and of TNF-,. Moreover, while phagocytosis may be necessary, it seems not to be crucial to the induction of cell death by the mycobacteria. [source] Interaction of 14-3-3 with Bid during seizure-induced neuronal deathJOURNAL OF NEUROCHEMISTRY, Issue 2 2003Sachiko Shinoda Abstract Seizure-induced neuronal death may involve coordinated intracellular trafficking and protein,protein interactions of members of the Bcl-2 family. The 14-3-3 proteins are known to sequester certain pro-apoptotic members of this family. BH3-interacting domain death agonist (Bid) may contribute to seizure-induced neuronal death, although regulation by 14-3-3 has not been reported. In this study we examined whether 14-3-3 proteins interact with Bid during seizure-induced neuronal death. Brief seizures were evoked in rats by intraamygdala microinjection of kainic acid to elicit unilateral hippocampal CA3 neuronal death. Coimmunoprecipitation analysis demonstrated that although Bcl-2-associated death promoter (Bad) constitutively bound 14-3-3, there was no interaction between Bid and 14-3-3 in control brain. Seizures triggered Bid cleavage and a commensurate increase in binding of Bid to 14-3-3 within injured hippocampus. Casein kinases I and II, which can inactivate Bid by phosphoserine/threonine modification, did not coimmunoprecipitate with Bid. The largely uninjured contralateral hippocampus did not exhibit Bid cleavage or binding of 14-3-3 to Bid. In vitro experiments confirmed that 14-3-3, is capable of binding truncated Bid, likely in the absence of phosphoserine/threonine modification. These data suggest 14-3-3 proteins may target active as well as inactive conformations of pro-apoptotic Bcl-2 death agonists, highlighting novel targets for intervention in seizure-induced neuronal death. [source] | ||||||||||