Página 1 dos resultados de 4568 itens digitais encontrados em 0.014 segundos

‣ Lentiviral-mediated RNAi targeting caspase-3 inhibits apoptosis induced by serum deprivation in rat endplate chondrocytes in vitro

Ding,L.; Wu,J.P.; Xu,G.; Zhu,B.; Zeng,Q.M.; Li,D.F.; Lu,W.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 Português
Relevância na Pesquisa
468.1903%
Current studies find that degenerated cartilage endplates (CEP) of vertebrae, with fewer diffusion areas, decrease nutrient supply and accelerate intervertebral disc degeneration. Many more apoptotic cells have been identified in degenerated than in normal endplates, and may be responsible for the degenerated grade. Previous findings suggest that inhibition of apoptosis is one possible approach to improve disc regeneration. It is postulated that inhibition of CEP cell apoptosis may be responsible for the regeneration of endplates. Caspase-3, involved in the execution phase of apoptosis, is a candidate for regulating the apoptotic process. In the present study, CEP cells were incubated in 1% fetal bovine serum. Activated caspases were detected to identify the apoptotic pathway, and apoptosis was quantified by flow cytometry. Lentiviral caspase-3 short hairpin RNA (shRNA) was employed to study its protective effects against serum deprivation. Silencing of caspase-3 expression was quantified by reverse transcription-polymerase chain reaction and Western blots, and inhibition of apoptosis was quantified by flow cytometry. Serum deprivation increased apoptosis of rat CEP cells through activation of a caspase cascade. Lentiviral caspase-3 shRNA was successfully transduced into CEP cells...

‣ Electroacupuncture inhibits apoptosis in annulus fibrosis cells through suppression of the mitochondria-dependent pathway in a rat model of cervical intervertebral disc degradation

Liao,Jun; Ke,Meigui; Xu,Teng; Lin,Lili
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 Português
Relevância na Pesquisa
473.37297%
The purpose of this study was to investigate whether treatment with electroacupuncture (EA) inhibited mitochondria-dependent apoptosis in annulus fibrosis (AF) cells in a rat model of cervical intervertebral disc degradation induced by unbalanced dynamic and static forces. Forty Sprague-Dawley rats were used in this study, of which 30 underwent surgery to induce cervical intervertebral disc degradation, 10 rats received EA at acupoints Dazhui (DU 14) and Shousanli (LI 10). TUNEL staining was measured to assess apoptosis in AF cells, immunohistochemistry was used to examine Bcl-2 and Bax expression, colorimetric assays were used to determine caspase 9 and caspase 3 activities and RT-PCR and western blotting were used to assess the mRNA and protein expression of Crk and ERK2. Treatment with EA reduced the number of AF-positive cells in TUNEL staining, increased Bcl-2-positive cells and decreased Bax-positive cells in immunohistochemical staining, significantly inhibited the activation of caspases-9 and -3, and enhanced the mRNA and protein expression of Crk and ERK2. Our data show that EA inhibits AF cell apoptosis via the mitochondria-dependent pathway and up-regulates Crk and ERK2 expression. These results suggest that treatment with may be a good alternative therapy for preventing cervical spondylosis.

‣ The Ets2 Transcription Factor Inhibits Apoptosis Induced by Colony-Stimulating Factor 1 Deprivation of Macrophages through a Bcl-xL-Dependent Mechanism

Sevilla, Lidia; Aperlo, Christel; Dulic, Vjekoslav; Chambard, Jean Claude; Boutonnet, Christel; Pasquier, Olivier; Pognonec, Philippe; Boulukos, Kim E.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /04/1999 Português
Relevância na Pesquisa
473.37297%
Bcl-xL, a member of the Bcl-2 family, inhibits apoptosis, and its expression is regulated at the transcriptional level, yet nothing is known about the transcription factors specifically activating this promoter. The bcl-x promoter contains potential Ets binding sites, and we show that the transcription factor, Ets2, first identified by its sequence identity to v-ets of the E26 retrovirus, can transactivate the bcl-x promoter. Transient expression of Ets2 results in the upregulation of Bcl-xL but not of Bcl-xS, an alternatively spliced gene product which induces apoptosis. Ets2 is ubiquitously expressed at low levels in a variety of cell types and tissues but is specifically induced to abundant levels during macrophage differentiation. Since Bcl-xL is also upregulated during macrophage differentiation, we asked whether the bcl-x could be a direct downstream target gene of Ets2 in macrophages. BAC1.2F5 macrophages, which are dependent on macrophage colony-stimulating factor 1 (CSF-1) for their growth and survival, were used in these studies. We show that CSF-1 stimulation of BAC1.2F5 macrophages results in the upregulation of expression of ets2 and bcl-xL with similar kinetics of induction. In the absence of CSF-1, these macrophages undergo cell death by apoptosis...

‣ Cytochrome P450 Epoxygenase Metabolism of Arachidonic Acid Inhibits Apoptosis

Chen, Jian-Kang; Capdevila, Jorge; Harris, Raymond C.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2001 Português
Relevância na Pesquisa
481.88477%
The ubiquitous cytochrome P450 hemoproteins play important functional roles in the metabolism and detoxification of foreign chemicals. However, other than established roles in cholesterol catabolism and steroid hormone biosynthesis, their cellular and/or organ physiological functions remain to be fully characterized. Here we show that the cytochrome P450 epoxygenase arachidonic acid metabolite 14,15-epoxyeicosatrienoic acid (14,15-EET) inhibits apoptosis induced by serum withdrawal, H2O2, etoposide, or excess free arachidonic acid (AA), as determined by DNA laddering, Hoechst staining, and fluorescein isothiocyanate-labeled annexin V binding. In the stable transfectants (BM3 cells) expressing a mutant bacterial P450 AA epoxygenase, F87V BM3, which was genetically engineered to metabolize arachidonic acid only to 14,15-EET, AA did not induce apoptosis and protected against agonist-induced apoptosis. Ceramide assays demonstrated increased AA-induced ceramide production within 1 h and elevated ceramide levels for up to 48 h, the longest time tested, in empty-vector-transfected cells (Vector cells) but not in BM3 cells. Inhibition of cytochrome P450 activity by 17-octadecynoic acid restored AA-induced ceramide production in BM3 cells. Exogenous C2-ceramide markedly increased apoptosis in quiescent Vector cells as well as BM3 cells...

‣ Akt Inhibits Apoptosis Downstream of BID Cleavage via a Glucose-Dependent Mechanism Involving Mitochondrial Hexokinases

Majewski, Nathan; Nogueira, Veronique; Robey, R. Brooks; Hay, Nissim
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/2004 Português
Relevância na Pesquisa
481.24383%
The serine/threonine kinase Akt/protein kinase B inhibits apoptosis induced by a variety of stimuli, including overexpression or activation of proapoptotic Bcl-2 family members. The precise mechanisms by which Akt prevents apoptosis are not completely understood, but Akt may function to maintain mitochondrial integrity, thereby preventing cytochrome c release following an apoptotic insult. This effect may be mediated, in part, via promotion of physical and functional interactions between mitochondria and hexokinases. Here we show that growth factor deprivation induced proteolytic cleavage of the proapoptotic Bcl-2 family member BID to yield its active truncated form, tBID. Activated Akt inhibited mitochondrial cytochrome c release and apoptosis following BID cleavage. Akt also antagonized tBID-mediated BAX activation and mitochondrial BAK oligomerization, two downstream events thought to be critical for tBID-induced apoptosis. Glucose deprivation, which impaired the ability of Akt to maintain mitochondrion-hexokinase association, prevented Akt from inhibiting BID-mediated apoptosis. Interestingly, tBID independently elicited dissociation of hexokinases from mitochondria, an effect that was antagonized by activated Akt. Ectopic expression of the amino-terminal half of hexokinase II...

‣ Rac1 Inhibits Apoptosis in Human Lymphoma Cells by Stimulating Bad Phosphorylation on Ser-75

Zhang, Baolin; Zhang, Yaqin; Shacter, Emily
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /07/2004 Português
Relevância na Pesquisa
473.37297%
The small GTPase Rac1 has emerged as an important regulator of cell survival and apoptosis, but the mechanisms involved are not completely understood. In this report, constitutively active Rac1 is shown to stimulate the phosphorylation of the Bcl-2 family member Bad, thereby suppressing drug-induced caspase activation and apoptosis in human lymphoma cells. Rac1 activation leads to human Bad phosphorylation specifically at serine-75 (corresponding to murine serine-112) both in vivo and in vitro. Inhibition of constitutive and activated Rac1-induced Bad phosphorylation by a cell-permeable competitive peptide inhibitor representing this Bad phosphorylation site sensitizes lymphoma cells to drug-induced apoptosis. The data show further that endogenous protein kinase A is a primary catalyst of cellular Bad phosphorylation in response to Rac activation, while Akt is not involved. These findings define a mechanism by which active Rac1 promotes lymphoma cell survival and inhibits apoptosis in response to cancer chemotherapy drugs.

‣ Mitochondrial survivin inhibits apoptosis and promotes tumorigenesis

Dohi, Takehiko; Beltrami, Elena; Wall, Nathan R.; Plescia, Janet; Altieri, Dario C.
Fonte: American Society for Clinical Investigation Publicador: American Society for Clinical Investigation
Tipo: Artigo de Revista Científica
Publicado em 15/10/2004 Português
Relevância na Pesquisa
474.72035%
Evasion of apoptosis is a hallmark of cancer, but the molecular circuitries of this process are not understood. Here we show that survivin, a member of the inhibitor of apoptosis gene family that is overexpressed in cancer, exists in a novel mitochondrial pool in tumor cells. In response to cell death stimulation, mitochondrial survivin is rapidly discharged in the cytosol, where it prevents caspase activation and inhibits apoptosis. Selective targeting of survivin to mitochondria enhances colony formation in soft agar, accelerates tumor growth in immunocompromised animals, and abolishes tumor cell apoptosis in vivo. Therefore, mitochondrial survivin orchestrates a novel pathway of apoptosis inhibition, which contributes to tumor progression.

‣ Benzyloxycarbonyl-Val-Ala-Asp (OMe) fluoromethylketone (Z-VAD.FMK) inhibits apoptosis by blocking the processing of CPP32.

Slee, E A; Zhu, H; Chow, S C; MacFarlane, M; Nicholson, D W; Cohen, G M
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/04/1996 Português
Relevância na Pesquisa
471.50742%
Interleukin-1 beta converting enzyme (ICE)-like proteases, which are synthesized as inactive precursors, play a key role in the induction of apoptosis. We now demonstrate that benzyloxycarbonyl-Val-Ala-Asp (OMe) fluoromethylketone (Z-VAD.FMK), an ICE-like protease inhibitor, inhibits apoptosis by preventing the processing of CPP32 to its active form. These results suggest that novel inhibitors of apoptosis can be developed which prevent processing of proforms of ICE-like proteases.

‣ Nicotine inhibits apoptosis induced by chemotherapeutic drugs by up-regulating XIAP and survivin

Dasgupta, Piyali; Kinkade, Rebecca; Joshi, Bharat; DeCook, Christina; Haura, Eric; Chellappan, Srikumar
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
471.50742%
Non-small cell lung cancer (NSCLC) demonstrates a strong etiologic association with smoking. Although nicotine is not carcinogenic, it can induce cell proliferation and angiogenesis and suppress apoptosis induced by certain agents. Here we show that nicotine inhibits apoptosis induced by the drugs gemcitabine, cisplatin, and taxol, which are used to treat NSCLCs. This protection correlated with the induction of XIAP and survivin by nicotine in a panel of human NSCLC cell lines, and depletion of XIAP and survivin ablated the protective effects of nicotine. The antiapoptotic effects of nicotine were mediated by dihydro β-erythroidine-sensitive α3-containing nicotinic acetylcholine receptors and required the Akt pathway. Chromatin immunoprecipitation assays demonstrated that nicotine stimulation caused an increased recruitment of E2F1 and concomitant dissociation of retinoblastoma tumor suppressor protein (Rb) from survivin promoter in A549 cells. Moreover, ablation of E2F1 levels caused abrogation of the protective effects of nicotine against cisplatin-induced apoptosis in A549 cells whereas ablation of signal transducer and activator of transcription 3 levels had no effect. These studies suggest that exposure to nicotine might negatively impact the apoptotic potential of chemotherapeutic drugs and that survivin and XIAP play a key role in the antiapoptotic activity of nicotine.

‣ AIM Inhibits Apoptosis of T Cells and NKT Cells in Corynebacterium-Induced Granuloma Formation in Mice

Kuwata, Kazuhisa; Watanabe, Hisami; Jiang, Shu-Ying; Yamamoto, Takashi; Tomiyama-Miyaji, Chikako; Abo, Toru; Miyazaki, Toru; Naito, Makoto
Fonte: American Society for Investigative Pathology Publicador: American Society for Investigative Pathology
Tipo: Artigo de Revista Científica
Publicado em /03/2003 Português
Relevância na Pesquisa
475.73906%
Apoptosis inhibitor expressed by macrophages (AIM) inhibits apoptosis of CD4+CD8+ (CD4/CD8) double-positive thymocytes, and supports the viability of these cells on the thymic selection. However, pleiotropic functions of AIM have been suggested. In this study, heat-killed Corynebacterium parvum (C. parvum) was injected into mice carrying the homozygous mutation (AIM−/−) and wild-type (AIM+/+) mice, to investigate the role of AIM in the formation of hepatic granulomas. In AIM−/− mice, the size and the number of hepatic granulomas were larger, and the resorption of granulomas was more delayed than in AIM+/+ mice. The production of interleukin-12 was more prominent in AIM−/− mice than in AIM+/+ mice. In the liver of AIM+/+ mice, expression of AIM messenger ribonucleic acid (mRNA) increased after C. parvum injection. In situ hybridization demonstrated that AIM mRNA was expressed in Kupffer cells and exudate macrophages in the liver, especially in granulomas. Larger numbers of T cells and natural killer T (NKT) cells underwent apoptosis in the granulomas of AIM−/− mice, suggesting that AIM prevents apoptosis of NKT cells and T cells in C. parvum-induced inflammation. Recombinant AIM (rAIM) protein significantly inhibited apoptosis of NKT cells and T cells obtained from C. parvum-stimulated livers in vitro. These results indicate that AIM functions to induce resistance to apoptosis within NKT cells and T cells...

‣ Activation of the Lutropin/Choriogonadotropin Receptor Inhibits Apoptosis of Immature Leydig Cells in Primary Culture

Tai, Ping; Shiraishi, Koji; Ascoli, Mario
Fonte: The Endocrine Society Publicador: The Endocrine Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
478.08047%
We used proliferating primary cultures of immature rat Leydig cells expressing the recombinant human LH/choriogonadotropin (CG) receptor (LHR) to test the hypothesis that activation of this receptor inhibits apoptosis. We also compared the effects of LH/CG with epidermal growth factor (EGF) and IGF-I because these have been previously shown to stimulate proliferation and/or inhibit apoptosis in Leydig cells. Human CG (hCG), EGF, and IGF-I stimulated the phosphorylation of ERK1/2 and Akt in primary cultures of immature rat Leydig cells. These three hormones also robustly stimulated thymidine incorporation and inhibited drug-induced apoptosis. Using selective inhibitors of ERK1/2 (UO126) or Akt phosphorylation (LY294002), we show that the ERK1/2 and Akt cascades are both involved in the hCG- and EGF-dependent proliferation of Leydig cells, but only the ERK1/2 cascade is involved in their antiapoptotic actions. The same strategy showed that the proliferative and antiapoptotic actions of IGF-I are mediated entirely by the Akt pathway. These results show that activation of the LHR inhibits apoptosis in Leydig cells and that it does so through stimulation of the ERK1/2 pathway.

‣ Localization of Sequences in a Protein (ORF2) Encoded by the Latency-Related Gene of Bovine Herpesvirus 1 That Inhibits Apoptosis and Interferes with Notch1-Mediated trans-Activation of the bICP0 Promoter▿

Sinani, Devis; Jones, Clinton
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /12/2011 Português
Relevância na Pesquisa
482.32473%
Bovine herpesvirus 1 (BHV-1) infection induces clinical symptoms in the upper respiratory tract, inhibits immune responses, and can result in life-threatening secondary bacterial infections. Following acute infection, BHV-1 establishes latency in sensory neurons within trigeminal ganglia. Periodically, reactivation from latency occurs, resulting in virus transmission. The latency-related (LR) RNA is abundantly expressed in latently infected sensory neurons, suggesting that LR gene products regulate the latency-reactivation cycle. An LR mutant virus with stop codons at the amino terminus of the first open reading frame (ORF) in the LR gene (ORF2) does not reactivate from latency, in part because it induces higher levels of apoptosis in infected neurons. ORF2 inhibits apoptosis in transiently transfected cells, suggesting that it plays an important role in the latency-reactivation cycle. ORF2 also interacts with Notch1 or Notch3 and consequently inhibits their ability to trans-activate the bICP0 early and glycoprotein C promoters. In this study, we identified ORF2 sequences that were necessary for inhibiting cold shock-induced apoptosis or Notch1-mediated trans-activation of the bICP0 early promoter and stimulation of productive infection. Relative to ORF2 sequences necessary for inhibiting apoptosis...

‣ Viral FLICE Inhibitory Protein of Rhesus Monkey Rhadinovirus Inhibits Apoptosis by Enhancing Autophagosome Formation

Ritthipichai, Krit; Nan, Yuchen; Bossis, Ioannis; Zhang, Yanjin
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 20/06/2012 Português
Relevância na Pesquisa
478.14395%
Rhesus monkey rhadinovirus (RRV) is a gamma-2 herpesvirus closely related to human herpesvirus 8 (HHV8). RRV encodes viral FLICE inhibitory protein (vFLIP), which has death effector domains. Little is known about RRV vFLIP. This study intended to examine its function in apoptosis. Here we found that RRV vFLIP inhibits apoptosis induced by tumor necrosis factor-α (TNF-α) and cycloheximide. In HeLa cells with vFLIP expression, the cleavage of poly [ADP-ribose] polymerase 1 (PARP-1) and activities of caspase 3, 7, and 9 were much lower than those in controls. Cell viability of HeLa cells with vFLIP expression was significantly higher than control cells after apoptosis induction. However, RRV vFLIP appears unable to induce NF-κB signaling when tested in NF-κB reporter assay. RRV vFLIP was able to enhance cell survival under starved conditions or apoptosis induction. At early time points after apoptosis induction, autophagosome formation was enhanced and LC3-II level was elevated in cells with vFLIP and, when autophagy was blocked with chemical inhibitors, these cells underwent apoptosis. Moreover, RRV latent infection of BJAB B-lymphoblastoid cells protects the cells against apoptosis by enhancing autophagy to maintain cell survival. Knockdown of vFLIP expression in the RRV-infected BJAB cells with siRNA abolished the protection against apoptosis. These results indicate that vFLIP protects cells against apoptosis by enhancing autophagosome formation to extend cell survival. The finding of vFLIP’s inhibition of apoptosis via the autophagy pathway provides insights of vFLIP in RRV pathogenesis.

‣ Overexpression of the hydatidiform mole-related gene F10 inhibits apoptosis in A549 cells through downregulation of BCL2-associated X protein and caspase-3

SONG, YALI; ZHANG, GONG; ZHU, XIULAN; PANG, ZHANJUN; XING, FUQI; QUAN, SONG
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
473.37297%
The aim of this study was to investigate how the overexpression of the hydatidiform mole-related gene F10 affects apoptosis in human lung cancer A549 cells. A549 cells were transfected with pEGFP-N1-F10 (A549-F10) or pEGFP-N1 empty vector (A549-empty). Untransfected A549, A549-F10 or A549-empty cells were examined using the MTT cell proliferation assay and the TUNEL-FITC/Hoechst 33258 apoptosis assay. Western blotting was used to examine the expression levels of the pro-apoptotic genes, BCL2-associated X protein (BAX) and caspase-3. F10 was stably expressed in A549 cells. From 12 h, A549-F10 cells proliferated markedly faster than the untransfected and A549-empty cells. F10 overexpression also significantly inhibited apoptosis, as shown by the reduced number of TUNEL and Hoechst 33258 double-positive cells. This inhibition was likely due to an F10-induced reduction in the BAX and caspase-3 levels. The results of this study indicate that F10 overexpression inhibits apoptosis in A549 cells through the downregulation of the pro-apoptotic genes BAX and caspase-3.

‣ Astaxanthin inhibits apoptosis in alveolar epithelial cells type II in vivo and in vitro through the ROS-dependent mitochondrial signalling pathway

Song, Xiaodong; Wang, Bingsi; Lin, Shengcui; Jing, Lili; Mao, Cuiping; Xu, Pan; Lv, Changjun; Liu, Wen; Zuo, Ji
Fonte: BlackWell Publishing Ltd Publicador: BlackWell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
468.75348%
Oxidative stress is an important molecular mechanism underlying lung fibrosis. The mitochondrion is a major organelle for oxidative stress in cells. Therefore, blocking the mitochondrial signalling pathway may be the best therapeutic manoeuver to ameliorate lung fibrosis. Astaxanthin (AST) is an excellent antioxidant, but no study has addressed the pathway of AST against pulmonary oxidative stress and free radicals by the mitochondrion-mediated signalling pathway. In this study, we investigated the antioxidative effects of AST against H2O2- or bleomycin (BLM)-induced mitochondrial dysfunction and reactive oxygen species (ROS) production in alveolar epithelial cells type II (AECs-II) in vivo and in vitro. Our data show that AST blocks H2O2- or BLM-induced ROS generation and dose-dependent apoptosis in AECs-II, as characterized by changes in cell and mitochondria morphology, translocation of apoptotic proteins, inhibition of cytochrome c (Cyt c) release, and the activation of caspase-9, caspase-3, Nrf-2 and other cytoprotective genes. These data suggest that AST inhibits apoptosis in AECs-II cells through the ROS-dependent mitochondrial signalling pathway and may be of potential therapeutic value in lung fibrosis treatment.

‣ Iridovirus CARD Protein Inhibits Apoptosis through Intrinsic and Extrinsic Pathways

Chen, Chien-Wen; Wu, Ming-Shan; Huang, Yi-Jen; Lin, Pei-Wen; Shih, Chueh-Ju; Lin, Fu-Pang; Chang, Chi-Yao
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 05/06/2015 Português
Relevância na Pesquisa
474.72035%
Grouper iridovirus (GIV) belongs to the genus Ranavirus of the family Iridoviridae; the genomes of such viruses contain an anti-apoptotic caspase recruitment domain (CARD) gene. The GIV-CARD gene encodes a protein of 91 amino acids with a molecular mass of 10,505 Daltons, and shows high similarity to other viral CARD genes and human ICEBERG. In this study, we used Northern blot to demonstrate that GIV-CARD transcription begins at 4 h post-infection; furthermore, we report that its transcription is completely inhibited by cycloheximide but not by aphidicolin, indicating that GIV-CARD is an early gene. GIV-CARD-EGFP and GIV-CARD-FLAG recombinant proteins were observed to translocate from the cytoplasm into the nucleus, but no obvious nuclear localization sequence was observed within GIV-CARD. RNA interference-mediated knockdown of GIV-CARD in GK cells infected with GIV inhibited expression of GIV-CARD and five other viral genes during the early stages of infection, and also reduced GIV infection ability. Immunostaining was performed to show that apoptosis was effectively inhibited in cells expressing GIV-CARD. HeLa cells irradiated with UV or treated with anti-Fas antibody will undergo apoptosis through the intrinsic and extrinsic pathways...

‣ Insulin-like growth factor-II (IGF-II) prevents proinflammatory cytokine-induced apoptosis and significantly improves islet survival after transplantation

Hughes, A.; Mohanasundaram, D.; Kireta, S.; Jessup, C.; Drogemuller, C.; Coates, P.
Fonte: Lippincott Williams & Wilkins Publicador: Lippincott Williams & Wilkins
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
Relevância na Pesquisa
464.386%
BACKGROUND: The early loss of functional islet mass (50-70%) due to apoptosis after clinical transplantation contributes to islet allograft failure. Insulin-like growth factor (IGF)-II is an antiapoptotic protein that is highly expressed in β-cells during development but rapidly decreases in postnatal life. METHODS: We used an adenoviral (Ad) vector to overexpress IGF-II in isolated rat islets and investigated its antiapoptotic action against exogenous cytokines interleukin-1β- and interferon-γ-induced islet cell death in vitro. Using an immunocompromised marginal mass islet transplant model, the ability of Ad-IGF-II-transduced rat islets to restore euglycemia in nonobese diabetic/severe combined immunodeficient diabetic recipients was assessed. RESULTS: Ad-IGF-II transduction did not affect islet viability or function. Ad-IGF-II cytokine-treated islets exhibited decreased cell death (40% ± 2.8%) versus Ad-GFP and untransduced control islets (63.2% ± 2.5% and 53.6% ± 2.3%, respectively). Ad-IGF-II overexpression during cytokine treatment resulted in a marked reduction in terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive apoptotic cells (8.3% ± 1.4%) versus Ad-GFP control (41% ± 4.2%) and untransduced control islets (46.5% ± 6.2%). Western blot analysis confirmed that IGF-II inhibits apoptosis via activation of the phosphatidylinositol 3-kinase/Akt signaling pathway. Transplantation of IGF-II overexpressing islets under the kidney capsule of diabetic mice restored euglycemia in 77.8% of recipients compared with 18.2% and 47.5% of Ad-GFP and untransduced control islet recipients...

‣ Untersuchungen zur Inhibition der Apoptose von Mono Mac 6-Zellen durch B. henselae; Inhibition of apoptosis in Mono Mac 6 cells by Bartonella henselae

Schairer, Annette
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
478.51742%
B. henselae ist ein fakultativ intrazellulär wachsendes Bakterium und ruft beim Menschen die vaskuloproliferativen Krankheitsbilder Bazilläre Angiomatose und Peliosis hepatis hervor. Bekannt ist, dass B. henselae die Apoptose von Endothelzellen inhibiert, zudem bewirkt eine B. henselae-Infektion die Sekretion von VEGF bei verschiedenen Wirtszellen. Im Rahmen der vorliegenden Dissertation wurde gezeigt, dass eine Infektion mit B. henselae Marseille dosisabhängig zur Inhibition der PDTC-induzierten Apoptose von Mono Mac 6-Zellen führt. B. henselae Houston-1 und B. quintana Toulouse waren ebenfalls zur Apoptoseinhibition befähigt. Weiterhin wurden die zugrundeliegenden Pathogenitäts-mechanismen auf Bakterien- und Wirtszellseite näher charakterisiert. Auf zellulärer Ebene sind eine Aktivierung von NK-kB sowie eine Unterdrückung der Aktivierung von Caspase 3 beteiligt. Die Infektion durch B. henselae induziert eine Produktion von VEGF in Mono Mac 6-Zellen, die ihrerseits nicht verantwortlich für die Inhibition der Apoptose durch B. henselae ist. Zudem wurde gezeigt, dass ein direkter Kontakt zwischen B. henselae und der Wirtszelle nötig ist, um die Apoptose der Wirtszellen zu inhibieren, jedoch keine Viabilität der Bakterien vorliegen muss. Weiterhin ist das Oberflächenprotein BadA für die Inhibition der Apoptose von entscheidender Bedeutung. Experimente mit Transposon-Mutanten von B. henselae ergaben...

‣ Variola virus F1L is a Bcl-2-like protein that unlike its vaccinia virus counterpart inhibits apoptosis independent of Bim

Marshall, B; Puthalakath, H; Caria, S; Chugh, S; Doerflinger, M; Colman, P M; Kvansakul, M
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
474.72035%
Subversion of host cell apoptosis is an important survival strategy for viruses to ensure their own proliferation and survival. Certain viruses express proteins homologous in sequence, structure and function to mammalian pro-survival B-cell lymphoma 2 (Bcl-2) proteins, which prevent rapid clearance of infected host cells. In vaccinia virus (VV), the virulence factor F1L was shown to be a potent inhibitor of apoptosis that functions primarily be engaging pro-apoptotic Bim. Variola virus (VAR), the causative agent of smallpox, harbors a homolog of F1L of unknown function. We show that VAR F1L is a potent inhibitor of apoptosis, and unlike all other characterized anti-apoptotic Bcl-2 family members lacks affinity for the Bim Bcl-2 homology 3 (BH3) domain. Instead, VAR F1L engages Bid BH3 as well as Bak and Bax BH3 domains. Unlike its VV homolog, variola F1L only protects against Bax-mediated apoptosis in cellular assays. Crystal structures of variola F1L bound to Bid and Bak BH3 domains reveal that variola F1L forms a domain-swapped Bcl-2 fold, which accommodates Bid and Bak BH3 in the canonical Bcl-2-binding groove, in a manner similar to VV F1L. Despite the observed conservation of structure and sequence, variola F1L inhibits apoptosis using a startlingly different mechanism compared with its VV counterpart. Our results suggest that unlike during VV infection...

‣ Drosophila BRUCE inhibits apoptosis through non-lysine ubiquitination of the IAP-antagonist REAPER

Domingues, C; Ryoo, H D
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
473.37297%
Active caspases execute apoptosis to eliminate superfluous or harmful cells in animals. In Drosophila, living cells prevent uncontrolled caspase activation through an inhibitor of apoptosis protein (IAP) family member, dIAP1, and apoptosis is preceded by the expression of IAP-antagonists, such as Reaper, Hid and Grim. Strong genetic modifiers of this pathway include another IAP family gene encoding an E2 ubiquitin conjugating enzyme domain, dBruce. Although the genetic effects of dBruce mutants are well documented, molecular targets of its encoded protein have remained elusive. Here, we report that dBruce targets Reaper for ubiquitination through an unconventional mechanism. Specifically, we show that dBruce physically interacts with Reaper, dependent upon Reaper's IAP-binding (IBM) and GH3 motifs. Consistently, Reaper levels were elevated in a dBruce −/− background. Unexpectedly, we found that dBruce also affects the levels of a mutant form of Reaper without any internal lysine residues, which normally serve as conventional ubiquitin acceptor sites. Furthermore, we were able to biochemically detect ubiquitin conjugation on lysine-deficient Reaper proteins, and knockdown of dBruce significantly reduced the extent of this ubiquitination. Our results indicate that dBruce inhibits apoptosis by promoting IAP-antagonist ubiquitination on unconventional acceptor sites.