164,232 research outputs found
Characterization of Bax Pore Formation Using Fluorescence Techniques
No full text Bax is a pro-apoptotic protein believed to permeabilize mitochondria during apoptosis. The mechanism Bax uses is not well understood. In this work, we use fluorescence techniques to shed light on how tBid activates Bax and we examine the topology of the pore-forming domain of Bax. The manner in which tBid promotes apoptosis via Bax activation is not known. Study of tBid and Bax interaction using a new FRET pair showed that the proteins only interacted in the presence ofmembranes. The Bax pore was shown to have a variable size distribution. A fluorescence technique of simultaneously measuring pore formation, Bax insertion and FRET showed that tBid interaction with Bax occurred before all the Bax inserted or formed pores in the liposomes. A chronological order is proposed for Bax pore formation. tBid first binds to liposomes. tBid proceeds to interact with Bax, and Bax inserts into the membrane. After insertion, Bax oligomerizes and forms small pores. More Bax is recruited and the pores become larger. The two central hairpin helices of Bax, helices 5 and 6, are known as the pore-forming domain. We used cysteine scanning with the environment sensitive fluoroprobe NBD to gain insight into the topology of these helices. Fluorescence intensity changes and emission blue shifts showed that residues in these helices undergo conformational reorganization during pore formation. In the activated oligomeric conformation, fluorescence lifetimes showed that helix 5 was more inaccessible to water than helix 6. Cobalt, a cationic NBD quencher, effectively quenched residues in the pore-forming domain, consistent with a pore that is lined with anionic lipid head groups. Quenching with nitroxide groups at various lipid depths showed that residues on helix 6 were most quenched by a shallow quencher, while residues on helix 5 were quenched by deeper quenchers. Compared to beta sheet pore-forming proteins, the data obtained suggests that Bax and possibly other alpha helical pore-forming proteins form a lipidic pore in a dynamic environment. Combined together, the data suggest a model for Bax in which helix 5 spans the bilayer, and helix 6 is buried just below the lipid headgroups of a toroidal pore. ThesisMaster of Science (MSc
Distinct promoter elements mediate the co-operative effect of Brn-3a and p53 on the p21 promoter and their antagonism on the Bax promoter
No full textAlthough the promoters of both the Bax and p21 genes are activated by p53, they differ in the effect on this activation of the POU family transcription factor Brn-3a. Thus, Brn-3a inhibits activation of the Bax promoter by p53 but enhances the ability of p53 to activate the p21 promoter. We demonstrate that repression of p53-mediated activation of the Bax promoter involves a complex upstream sequence in which two Brn-3a response elements flank the p53 response element. In contrast, a minimal p21 promoter is activated by Brn-3a and such activation cannot be abolished without abolishing basal promoter activity. Moreover, synergistic activation by Brn-3a and p53 continues to be observed when the p53-binding sites in the p21 promoter are substituted by the Bax p53 site or by the region of the Bax promoter essential for Brn-3a-mediated repression, indicating that the p21 core promoter plays a central role in this response. The significance of these effects is discussed in terms of the different responses of the Bax and p21 promoters and the overlapping but distinct roles of Brn-3a and p53 in neuronal growth arrest and apoptosis
Variations sur Cadet Roussel [music] /
No full textJ.W.C. 3835 (Publisher number). For voice and piano.; Title from list t.p.; "Harmonisées par Arnold Bax, Frank Bridge, Eugène Goossens, John Ireland."; Individual sections within the work by each of the composers are marked with their initials.; Pl. no.: J.W.C. 3835.; Also available online http://nla.gov.au/nla.mus-vn6005741
Trim17, novel E3 ubiquitin-ligase, initiates neuronal apoptosis
No full textAccumulating data indicate that the ubiquitin-proteasome system controls apoptosis by regulating the level and the function of key regulatory proteins. In this study, we identified Trim17, a member of the TRIM/RBCC protein family, as one of the critical E3 ubiquitin ligases involved in the control of neuronal apoptosis upstream of mitochondria. We show that expression of Trim17 is increased both at the mRNA and protein level in several in vitro models of transcription-dependent neuronal apoptosis. Expression of Trim17 is controlled by the PI3K/Akt/GSK3 pathway in cerebellar granule neurons (CGN). Moreover, the Trim17 protein is expressed in vivo, in apoptotic neurons that naturally die during post-natal cerebellar development. Overexpression of active Trim17 in primary CGN was sufficient to induce the intrinsic pathway of apoptosis in survival conditions. This pro-apoptotic effect was abolished in Bax(-/-) neurons and depended on the E3 activity of Trim17 conferred by its RING domain. Furthermore, knock-down of endogenous Trim17 and overexpression of dominant-negative mutants of Trim17 blocked trophic factor withdrawal-induced apoptosis both in CGN and in sympathetic neurons. Collectively, our data are the first to assign a cellular function to Trim17 by showing that its E3 activity is both necessary and sufficient for the initiation of neuronal apoptosis. Cell Death and Differentiation (2010) 17, 1928-1941; doi: 10.1038/cdd.2010.73; published online 18 June 201
Bcl-w promotes cell invasion by blocking the invasion-suppressing action of Bax
No full textThe Bcl-2 family members are key regulators of cellular viability, either promoting or suppressing cell death. Recent reports have indicated that the pro-survival members (Bcl-w, Bcl-X L, and others) also enhance the migratory and invasive potentials of cancer cells, although the mechanisms underlying this phenomenon have yet to be adequately elucidated. Herein, by using human cancer cells and mouse embryonic fibroblasts, we demonstrate that Bcl-w functions in the mitochondria to increase the levels of reactive oxygen species (ROS), which subsequently stimulates the invasion-promoting signaling pathway. By way of contrast, Bax, a member of the multidomain pro-apoptotic group (Bax and Bak), was found to reduce ROS levels, thereby suppressing cell invasion. Analyses of the functional relationship between Bcl-w and Bax have shown that Bcl-w requires Bax for promoting cell invasion, whereas Bax suppresses cell invasion in a Bcl-w-independent manner. By using a Bcl-w mutant (Bcl-w/G94A) that was found not to bind to Bax, we have further determined that Bcl-w should bind to Bax to promote cell invasion. Overall, the results indicate that Bcl-w enhances cellular invasiveness by binding to Bax and subsequently blocking its invasion-suppressing actions. Moreover, these functions of Bcl-w and Bax are mimicked by other pro-survival and pro-apoptotic members, such as Bcl-X L and Bak, respectively. We propose the balance between pro-survival and multidomain pro-apoptotic members as a novel determinant of cellular invasiveness. © 2012 Elsevier Inc.
Prof. Th. W. Adorno and the author Hans Erich Nossack.
No full textProf. Th. W. Adorno and the author Hans Erich Nossack at a reception of Insel Verlag, Buchmesse Frankfurt 1966LB
Estudo do efeito neuroprotetor da mirtazapina e imipramina e sua relação com a expressão gênica de proteínas apoptóticas
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em Neurociências.Neste estudo foram investigados a ação neuroprotetora dos antidepressivos mirtazapina e imipramina e os efeitos destes compostos sobre a expressão gênica de proteínas anti- e pró-apoptóticas em células de neuroblastoma humano (SH-5YSY). Mirtazapina e imipramina mostraram baixa citotoxicidade sobre neuroblastoma humano e nas concentrações de 1-10 ?M aumentaram a viabilidade celular. As células de neuroblastoma humano foram pré-tratadas com mirtazapina e imipramina e depois incubadas na presença de tapsigargina ou peróxido de hidrogênio (H2O2). O pré-tratamento com mirtazapina e imipramina protegeu as células de neuroblastoma da citotoxicidade induzida pelo peróxido de hidrogênio. As células foram incubadas com mirtazapina e imipramina e a expressão gênica (RNAm) das proteínas envolvidas na sobrevivência (Bcl-2) e na morte celular (Bax, Bad e p53) foram determinadas por transcrição reversa e reação em cadeia da polimerase quantititiva (qRT-PCR). A mirtazapina reduziu e a imipramina não afetou a expressão gênica da proteína Bcl-2. A expressão gênica das proteínas Bax e p53 foi bastante reduzida pela mirtazapina e imipramina. A mirtazapina e a imipramina (2 ?M) aumentaram a razão Bcl-2/Bax e Blc-2/p53, indicando um efeito positivo na sobrevivência celular. Os resultados sugerem que o efeito neuroprotetor da mirtazapina e da imipramina envolve a redução da expressão gênica das proteínas pró-apoptóticas Bax e p53.In this study we investigated the neuroprotective effect of mirtazapine and imipramine and how these compounds affect the gene expression of anti-apoptotic and pro-apoptotic proteins in human neuroblastoma cells SH-SY5Y. Mirtazapine and imipramine showed low cytotoxicity on neuroblastoma cells and at concentrations of 1-10 ìM they increased the cell viability. Human neuroblastoma cells were pre-treated with mirtazapine and imipramine and then incubated with thapsigargin or hydrogen peroxide (H2O2). The pre-treatment with mirtazapine and imipramine protected the cells against H2O2-induced cell death. Cells were incubated with mirtazapine and imipramine and gene expression (mRNA) was determined for anti-apoptotic (Bcl-2) and pro-apoptotic proteins (Bax, Bad and p53) through qRT-PCR. Mirtazapine reduced and imipramine did not affect the expression level of the anti-apoptotic protein Bcl-2. The expression of Bax and p53 were strongly reduced by mirtazapine and imipramine. Both antidepressants increased the expression ratio of Bcl-2/Bax and Bcl-2/p53. These data suggest that the neuroprotective effect of mirtazapine and imipramine might be due the downregulation of pro-apoptotic Bax and p53 expression
Ekspresja kaspazy-3, Bax i Bcl-2 w łożyskach ciąż leczonych i nieleczonych z powodu wewnątrzmacicznego zahamowania wzrastania płodu
No full textAbstract Background: Fetal growth restriction (FGR) is the reason of high prematurity rate and its later complications. Restriction of utero-placental circulation, which could be changed by IURG treatment, plays the main role in FGR. The results of changes in apoptosis-related genes expression due to FGR treatment may help further in the prevention and treatment of FGR. Material and methods: Caspase-3, Bax and Bcl-2 expressions in normal pregnancies and those complicated by treated and untreated FGR have been compared. The study was conducted in 2005-2006 at the High-Risk Pregnancy Unit of Medical University in Łódź and Kopernik Hospital in Łódź. Caspase-3, Bax and Bcl-2 expressions were assessed by immunohistochemical method. Bcl-2 was assessed in the trophoblast, Bax and caspase-3 in the decidua and the trophoblast. Results: The mean value of Bcl-2 in the trophoblast was 58.8±12.7 in the FGR-untreated group, 37.0±0.5 in the FGR-treated group and 65.7±6.9 in the control group. In the FGR-untreated group the mean value of Bax expression was 60.6±10.7 in the trophoblast and 32.0±7.3 in the decidua. In the FGR-treated group the mean value of Bax expression was 42.2±12.2 in the trophoblast and 20.9±6.4 in the decidua. In the control group the mean value of Bax expression was 13.6±2.2 in the trophoblast and 6.6±6.8 in the decidua. In the FGR-untreated group the mean value of Cpp-32 expression was 40.1±9.1 in the trophoblast and 42.6±.12.5 in the decidua. In the FGR-treated group the mean value of Cpp-32 expression was 21.3±6.8 in the trophoblast and 23.7±5.1 in the decidua. In the control group the mean value of Cpp-32 expression was 13,6±6,3 in trophoblast and 11.6±5.3 in the decidua. Conclusions: Increased expression of pro-apoptotic proteins in the placenta might be one of the reasons for FGR development. The treatment used in the FGR group decreased the process of apoptosis.Streszczenie Hipotrofia wewnątrzmaciczna (FGR) wiąże się z wysokim odsetkiem wcześniactwa i jego późniejszych powikłań. W patogenezie hipotrofii główną rolę odgrywa ograniczenie przepływu maciczno-łożyskowego, co może być modyfikowane przez stosowanie terapii. Uzyskanie zmian zachodzących podczas leczenia w zakresie procesu apoptozy może wpłynąć w przyszłości na sposób zapobiegania i leczenia hipotrofii wewnątrzmacicznej. Materiał i metody: Porównano ekspresję kaspazy-3, Bax i Bcl-2 w ciąży niepowikłanej i powikłanej hipotrofią wewnątrzmaciczną z podziałem na kobiety nieleczone i leczone. Badania były prowadzone w Klinice Patologii Ciąży Uniwersytetu Medycznego w Łodzi w latach 2005-2006. Ekspresję kaspazy-3, Bax i Bcl-2 oceniano metodami immunohistochemicznymi. Białko Bcl-2 było oceniane w trofoblaście, Bax i kaspaza-3 w doczesnej i trofoblaście. Wyniki: W grupie nieleczonych średnia wartość ekspresji Bcl-2 w trofoblaście wynosiła, 58,8±12,7, w grupie leczonych 37,0±10,5, w grupie kontrolnej 65,7±6,9. W grupie nieleczonych średnia wartość Bax w trofoblaście wynosiła 60,6±10,7, w doczesnej natomiast 32,0±7,3. W grupie kobiet leczonych średnia wartość ekspresji w trofoblaście wynosiła 42,2±12,2, w doczesnej natomiast 20,9±6,4. W grupie kontrolnej w trofoblaście wynosiła 13,6±2,2, a w doczesnej 6,6±6,8. W grupie nieleczonych średnia wartość kaspazy-3 mierzonej za pomocą aktywności Cpp-32 wynosiła w trofoblaście 40,1±9,1, a w doczesnej 42,6±12,5. W grupie kobiet leczonych średnia ekspresja Cpp-32 w trofoblaście wynosiła 21,3±6,8, w doczesnej 23,7±5,1. W grupie kontrolnej w trofoblaście wartość ekspresji Cpp-32 oceniano na 13,6±6,3, w doczesnej uzyskano wartości 11,6±5,3. Wnioski: Podwyższona ekspresja białek proapoptotycznych w łożysku może być jednym z powodów rozwoju hipotrofii wewnątrzmacicznej. Leczenie zastosowane w hipotrofii wewnątrzmacicznej obniżyło oceniane parametry apoptozy
Nowe spojrzenie na planowanie architektury mieszkaniowej w afryce subsaharyjskiej
No full textThe author shares his reflections on state of art in housing and urban planning, deficiencies, expectations and possibilities in the Sahel region of Africa. He notices, that the housing problem in Africa is one of the challenges, which should be solved in order to recover life dignity of African people and secure their rights to traditional family life in acceptable conditions. The paper describes the studies on the typical dispersed urban structures and the need to foster this type of settlement structure and proposals of introduction of new on light steel frame housing system in the area of Sahel, combining the traditional way of building houses with modern technology. The particularly analysed case, is the housing problem in the Republic of Chad. The author presents the basic discussion on this topic and his architectural proposals. Unfortunately, the gap between the needs and the financial feasibility of housing construction in this area, makes this project already at the starting point extremely difficult to be realized without external subventions.Problem mieszkaniowy w Afryce jest jednym z wyzwań, które należy rozwiązać, aby Afrykanie mogli odzyskać godność życiową i zabezpieczyć swoje prawa do tradycyjnego życia rodzinnego w akceptowalnych warunkach. W artykule opisano badania nad typowymi rozproszonymi strukturami miejskimi i potrzebą wspierania tego typu struktur osadniczych oraz propozycji wprowadzenia nowego systemu konstrukcji domów, opartym na lekkim szkielecie stalowym, łączącym tradycyjny sposób budowania domów z nowoczesną technologią. Przypadkiem szczególnie analizowanym jest problem mieszkaniowy w Republice Czadu. Autor przedstawia podstawową dyskusję na ten temat i swoje propozycje architektoniczne. Niestety luka między potrzebami mieszkaniowymi w Czadzie a finansową wykonalnością budownictwa mieszkaniowego w tym obszarze sprawia, że projekt ten, już w punkcie wyjścia, jest niezwykle trudny do realizacji bez uzyskania zewnętrznych dotacji
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