Appoptosin is a novel pro-apoptotic protein and mediates cell death in neurodegeneration.
Ontology highlight
ABSTRACT:
SUBMITTER: Zhang H
PROVIDER: S-EPMC3509748 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:The dopaminergic neurotoxin, 6-hydroxydopamine (6-OHDA), has been widely utilized to establish experimental models of Parkinson disease and to reveal the critical molecules and pathway underlying neuronal death. The profile of gene expression changes following 6-OHDA treatment of MN9D dopaminergic neuronal cells was investigated using a TwinChip Mouse-7.4K microarray. Functional clustering of altered sets of genes identified RING-finger protein 166 (RNF166). RNF166 is composed of an N-terminal RING domain and C-terminal ubiquitin interaction motif. RNF166 localized in the cytosol and nucleus. At the tissue level, RNF166 was widely expressed in the central nervous system and peripheral organs. In the cerebral cortex, its expression decreased over time. In certain conditions, overexpression of RNF166 accelerates the naturally occurring neuronal death and 6-OHDA-induced MN9D cell death as determined by TUNEL and annexin-V staining, and caspase activation. Consequently, 6-OHDA-induced apoptotic cell death was attenuated in RNF166-knockdown cells. In an attempt to elucidate the mechanism underlying this pro-apoptotic activity, binding protein profiles were assessed using the yeast two-hybrid system. Among several potential binding candidates, RNF166 was shown to interact with the cytoplasmic X-linked inhibitor of apoptosis (XIAP), inducing ubiquitin-dependent degradation of XIAP and eventually accelerating caspase activation following 6-OHDA treatment. RNF166's interaction with and resulting inhibition of the XIAP anti-caspase activity was further enhanced by XIAP-associated factor-1 (XAF-1). Consequently, depletion of RNF166 suppressed 6-OHDA-induced caspase activation and apoptotic cell death, which was reversed by XIAP knockdown. In summary, our data suggest that RNF166, a novel E3 ligase, plays a pro-apoptotic role via caspase activation in neuronal cells.
| S-EPMC7603511 | biostudies-literature
Project description:We previously demonstrated that protein kinase C? (PKC?; PKC delta) is an oxidative stress-sensitive kinase that plays a causal role in apoptotic cell death in neuronal cells. Although PKC? activation has been extensively studied, relatively little is known about the molecular mechanisms controlling PKC? expression. To characterize the regulation of PKC? expression, we cloned an ?2-kbp 5'-promoter segment of the mouse Prkcd gene. Deletion analysis indicated that the noncoding exon 1 region contained multiple Sp sites, including four GC boxes and one CACCC box, which directed the highest levels of transcription in neuronal cells. In addition, an upstream regulatory region containing adjacent repressive and anti-repressive elements with opposing regulatory activities was identified within the region -712 to -560. Detailed mutagenesis studies revealed that each Sp site made a positive contribution to PKC? promoter expression. Overexpression of Sp family proteins markedly stimulated PKC? promoter activity without any synergistic transactivating effect. Furthermore, experiments in Sp-deficient SL2 cells indicated long isoform Sp3 as the essential activator of PKC? transcription. Importantly, both PKC? promoter activity and endogenous PKC? expression in NIE115 cells and primary striatal cultures were inhibited by mithramycin A. The results from chromatin immunoprecipitation and gel shift assays further confirmed the functional binding of Sp proteins to the PKC? promoter. Additionally, we demonstrated that overexpression of p300 or CREB-binding protein increases the PKC? promoter activity. This stimulatory effect requires intact Sp-binding sites and is independent of p300 histone acetyltransferase activity. Finally, modulation of Sp transcriptional activity or protein level profoundly altered the cell death induced by oxidative insult, demonstrating the functional significance of Sp-dependent PKC? gene expression. Collectively, our findings may have implications for development of new translational strategies against oxidative damage.
| S-EPMC3103361 | biostudies-literature
Project description:Necroptosis is a physiologically relevant mode of cell death with some well-described initiating events, but largely unknown executioners. Here we investigated necrostatin-1 (Nec-1) sensitive death elicited by different necroptosis stimuli in L929 mouse fibrosarcoma cells, mouse embryonic fibroblasts (MEF) and bone marrow-derived macrophages. We found that TNF?- or zVAD-induced necroptosis occurs independently of the recently implicated executioners Bmf or PARP-2, but can involve the Bcl-2 family proteins Bid and Bak. Furthermore, this type of necroptosis is associated with mitochondrial cytochrome c release and partly sensitive to cyclosporine A inhibition, suggesting a cross talk with the mitochondrial permeability transition pore. Necroptosis triggered by cadmium (Cd) exposure caused fully Nec-1-sensitive and caspase-independent death in L929 cells that was associated with autocrine TNF?-mediated feed-forward signalling. In MEF Cd-exposure elicited a mixed mode of cell death that was to some extent Nec-1-sensitive but also displayed features of apoptosis. It was partly dependent on Bmf and Bax/Bak, proteins typically considered to act pro-apoptotic, but ultimately insensitive to caspase inhibition. Overall, our study indicates that inducers of "extrinsic" and "intrinsic" necroptosis can both trigger TNF-receptor signalling. Further, necroptosis may depend on mitochondrial changes engaging proteins considered critical for MOMP during apoptosis that ultimately contribute to caspase-independent necrotic cell death.
| S-EPMC4918797 | biostudies-literature
Project description:Neurodegenerative disease is characterized by the progressive deterioration of neuronal function caused by the degeneration of synapses, axons, and ultimately the death of nerve cells. An increased understanding of the mechanisms underlying altered cellular homeostasis and neurodegeneration is critical to the development of effective treatments for disease. Here, we review what is known about neuronal cell death and how it relates to our understanding of neurodegenerative disease pathology. First, we discuss prominent molecular signaling pathways that drive neuronal loss, and highlight the upstream cell biology underlying their activation. We then address how neuronal death may occur during disease in response to neuron intrinsic and extrinsic stressors. An improved understanding of the molecular mechanisms underlying neuronal dysfunction and cell death will open up avenues for clinical intervention in a field lacking disease-modifying treatments.
| S-EPMC6996453 | biostudies-literature
Project description:The pro-apoptotic protein Bim (B-cell lymphoma-2 (Bcl-2)-interacting modulator of cell death) has recently been identified and shown to promote cell death in response to several stimuli. In this report, we investigated the role of Bim in porcine follicular atresia. Initially, Bim cDNA was cloned and characterized from porcine ovarian tissue. Porcine Bim had three alternative splicing variants (Bim-extra long, Bim-long, and Bim-short), all containing the consensus Bcl-2 homology 3 domain. We then found the Bim-extra long (Bim(EL)) protein, the most abundant isoform of Bim, was strongly expressed and co-localized with apoptotic (TUNEL-positive) granulosa cells from porcine atretic follicles. Furthermore, overexpression of Bim(EL) triggered apoptosis in granulosa cells. In primary granulosa cell cultures under basal conditions, we observed that Bim(EL) expression was dampened by treatment with follicle-stimulating hormone (FSH). The role of the PI3K/Akt pathway in the regulation of repression was clarified by the use of the PI3K inhibitor, LY294002, and by transfection with Akt siRNA. Forkhead Box Protein O3a (FoxO3a), a well defined transcriptional activator of Bim, was phosphorylated at Ser-253 and inactivated after FSH stimulation. Also, FSH abolished FoxO3a nuclear accumulation in response to LY294002. Finally, chromatin immunoprecipitation assays demonstrated that FoxO3a directly bound and activated the bim promoter. Taken together, we conclude that Bim(EL) induces porcine granulosa cell apoptosis during follicular atresia, and its expression is regulated by FSH via the PI3K/Akt/FoxO3a pathway.
| S-EPMC3323030 | biostudies-literature
Project description:Overexpression of the adenine nucleotide translocase (ANT) has been shown to be cytotoxic in several cell types. Although ANT was originally proposed to be a critical component of the mitochondrial permeability transition (MPT) pore, recent data have suggested that this may not be the case. We therefore hypothesized that the cytotoxic actions of ANT are through an alternative mechanism, independent of the MPT pore. Infection of cultured neonatal cardiomyocytes with an ANT1-encoding adenovirus induced a gene dosage-dependent increase in cell death. However, ANT1 overexpression failed to induce MPT, and neither pharmacological nor genetic inhibition of the MPT pore was able to prevent ANT1-induced cell death. These data suggested that ANT1-induced death progressed through an MPT pore-independent pathway. Somewhat surprisingly, we observed that protein levels of Bax, a pro-apoptotic Bcl protein, were consistently elevated in ANT1-infected cardiomyocytes. Membranes isolated from ANT1-infected myocytes exhibited significantly increased amounts of membrane-inserted Bax, and immunocytochemistry revealed increased Bax activation in ANT1-infected myocytes. Co-expression with the Bax antagonist Bcl2 was able to greatly reduce the degree of ANT1-induced cell death. Furthermore, Bax/Bak-deficient fibroblasts were resistant to the cytotoxic effects of ANT1 overexpression. Interestingly, ANT1 overexpression was also associated with enhanced production of reactive oxygen species (ROS), and the antioxidant MnTBAP was able to significantly attenuate both the ANT1-induced upregulation of Bax and cell death. Taken together, these data indicate that ANT mediates cell death, not through the MPT pore, but rather via a ROS-dependent upregulation and activation of Bax.
| S-EPMC2768428 | biostudies-literature
Project description:Mitochondria are vital organelles to eukaryotic cells. Damage to mitochondria will cause irreversible cell death or apoptosis. In this report, we aim at programmed cancer cell death via specific mitochondrial damage. Herein, a functionalized pro-apoptotic peptide demonstrates a dual-targeting capability using folic acid (FA) (targeting agent I) and triphenylphosphonium (TPP) cation (targeting agent II). FA is a cancer-targeting agent, which can increase the cellular uptake of the pro-apoptotic peptide via receptor-mediated endocytosis. And the TPP cation is the mitochondrial targeting agent, which specifically delivers the pro-apoptotic peptide to its particular subcellular mitochondria after internalized by cancer cells. Then the pro-apoptotic peptide accumulates in mitochondria and causes its serious damage. This dual-targeting strategy has the potential to effectively transport the pro-apoptotic peptide to targeted cancer cell mitochondria, inducing mitochondrial dysfunction and triggering the mitochondria-dependent apoptosis to efficiently eliminate cancer cells.
| S-EPMC3863817 | biostudies-other
Project description:Fbxl7, a subunit of the SCF (Skp-Cul1-F-box protein) complex induces mitotic arrest in cells; however, molecular factors that control its cellular abundance remain largely unknown. Here, we identified that an orphan F-box protein, Fbxl18, targets Fbxl7 for its polyubiquitylation and proteasomal degradation. Lys 109 within Fbxl7 is an essential acceptor site for ubiquitin conjugation by Fbxl18. An FQ motif within Fbxl7 serves as a molecular recognition site for Fbxl18 interaction. Ectopically expressed Fbxl7 induces apoptosis in Hela cells, an effect profoundly accentuated after cellular depletion of Fbxl18 protein or expression of Fbxl7 plasmids encoding mutations at either Lys 109 or within the FQ motif. Ectopic expression of Fbxl18 plasmid-limited apoptosis caused by overexpressed Fbxl7 plasmid. Thus, Fbxl18 regulates apoptosis by mediating ubiquitin-dependent proteasomal degradation of the pro-apoptotic protein Fbxl7 that may impact cellular processes involved in cell cycle progression.
| S-EPMC4669792 | biostudies-literature
Project description:Tumor necrosis factor-alpha (TNF-alpha) is elevated in the serum as a result of aging and it promotes pro-apoptotic signaling upon binding to the type I TNF receptor. It is not known if activation of this apoptotic pathway contributes to the well-documented age-associated decline in muscle mass (i.e. sarcopenia). We tested the hypothesis that skeletal muscles from aged rodents would exhibit elevations in markers involved in the extrinsic apoptotic pathway when compared to muscles from young adult rodents, thereby contributing to an increased incidence of nuclear apoptosis in these muscles. The plantaris (fast) and soleus (slow) muscles were studied in young adult (5-7 mo, n=8) and aged (33 mo, n=8) Fischer(344) x Brown Norway rats. Muscles from aged rats were significantly smaller while exhibiting a greater incidence of apoptosis. Furthermore, muscles from aged rats had higher type I TNF receptor and Fas associated death domain protein (FADD) mRNA, protein contents for FADD, BCL-2 Interacting Domain (Bid), FLICE-inhibitory protein (FLIP), and enzymatic activities of caspase-8 and caspase-3 than muscles from young adult rats. Significant correlations were observed in the plantaris muscle between caspase activity and muscle weight and the apoptotic index, while similar relationships were not found in the soleus. These data demonstrate that pro-apoptotic signaling downstream of the TNF receptor is active in aged muscles. Furthermore, our data extend the previous demonstration that type II fibers are preferentially affected by aging and support the hypothesis that type II fiber containing skeletal muscles may be more susceptible to muscle mass loses via the extrinsic apoptotic pathway.
| S-EPMC5271588 | biostudies-literature
Project description:Harakiri (HRK) is a BH3-only protein of the Bcl-2 family and regulates apoptosis by interfering with anti-apoptotic Bcl-2 and Bcl-xL proteins. While its function is mainly characterized in the nervous system, its role in tumors is ill-defined with few studies demonstrating HRK silencing in tumors. In this study, we investigated the role of HRK in the most aggressive primary brain tumor, glioblastoma multiforme (GBM). We showed that HRK is differentially expressed among established GBM cell lines and that HRK overexpression can induce apoptosis in GBM cells at different levels. This phenotype can be blocked by forced expression of Bcl-2 and Bcl-xL, suggesting the functional interaction of Bcl-2/Bcl-xL and HRK in tumor cells. Moreover, HRK overexpression cooperates with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a known tumor-specific pro-apoptotic agent. Besides, secondary agents that augment TRAIL response, such as the histone deacetylase inhibitor MS-275, significantly increases HRK expression. In addition, GBM cell response to TRAIL and MS-275 can be partly abolished by HRK silencing. Finally, we showed that HRK induction suppresses tumor growth in orthotopic GBM models in vivo, leading to increased survival. Taken together, our results suggest that HRK expression is associated with GBM cell apoptosis and increasing HRK activity in GBM tumors might offer new therapeutic approaches.
| S-EPMC6368544 | biostudies-literature