Página 1 dos resultados de 5647 itens digitais encontrados em 0.006 segundos

Via de sinalização mTOR no carcinoma urotelial da bexiga

Pereira, Carla Sofia Domingues
Fonte: [s.n.] Publicador: [s.n.]
Tipo: Dissertação de Mestrado
Publicado em //2014 Português
Relevância na Pesquisa
37.016985%
Trabalho de Projeto apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Análises Laboratoriais Especializadas, área de especialização em Análise Biomédica; Mundialmente, o cancro da bexiga (CB) é o 7º tipo de cancro mais frequente em homens e o 17 º mais frequente em mulheres. É uma doença com etiologia multifatorial associada a vários agentes ambientais e genéticos, dos quais o tabagismo é o fator de risco mais importante. Os carcinomas uroteliais da bexiga (CUBs) são geralmente superficiais em 70% a 80% dos pacientes e invasores em 20% a 30%. Os CUBs não-invasores têm uma alta taxa de recorrência e progressão e os invasores e metastáticos representam a principal causa de morbidade e mortalidade entre os pacientes com CB. A via fosfatidilinositol-3cinase (PI3K) /AKT (Proteína cinase b) -alvo da rapamicina em mamíferos (m-TOR) é uma importante via envolvida no crescimento celular, tumorogénese, invasão celular e resposta a drogas. Esta via é frequentemente ativada em muitas neoplasias e o descontrolo da sinalização PI3K-AKT-mTOR no CB pode contribuir para o crescimento do tumor, angiogénese e metastização. Neste trabalho, foram estudados 96 casos de tumores diagnosticados como CUBs de vários graus e estádios e foi avaliada a imunoexpressão do phospho-mTOR (Ser2448) e do phospho-S6 (Ser235/236). Em relação à expressão do p-mTOR verificou-se que mais de 50% dos casos de CUB não apresentavam ou apresentavam uma baixa expressão desta proteína sendo que não foi encontrada associação deste com estádio ou grau de diferenciação tumoral. Em relação à proteína p-S6 a sua expressão nos CUB foi igualmente nula ou baixa...

Translational regulation mediated by internal ribosome entry sites of the MTOR and Δ133P53 human transcripts

Marques-Ramos, Ana
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
37.10545%
A regulação ao nível da iniciação da tradução de mRNAs é fundamental no processo de controlo de expressão génica uma vez que permite uma resposta celular rápida face a estímulos externos. Este controlo pode ocorrer de forma específica de transcrito, através de elementos reguladores em cis, tais como internal ribosome entry sites (IRESs), que medeiam a tradução de forma independente de alguns factores de iniciação canónicos que são inibidos em condições de stress celular, ou em algumas condições fisiológicas ou patológicas. Desta forma, a tradução dependente de IRES é refractária a condições que inibem a síntese proteica global. Estes elementos encontram-se em transcritos que codificam proteínas responsivas a stress, oncogenes ou supressores de tumor. O trabalho apresentado nesta dissertação mostra que os transcritos que codificam o mammalian (or mechanistic) target of rapamycin (MTOR) e a isoforma proteica de P53, Δ160P53, possuem elementos IRESs a regular a sua expressão. O MTOR é uma serina/treonina quinase conservada que integra sinais provenientes da estimulação por factores de crescimento, assim como dos estados nutricional e energético da célula actuando, nomeadamente, na maquinaria de tradução. Apesar da crescente compreensão acerca dos mecanismos de regulação e efeitos da via de sinalização do MTOR...

Atividade da via do mTOR no músculo esquelético da prole é afetada pelo consumo materno de dieta hiperlipídica e difere entre os animais neonatos e lactentes; MTOR pathway activity in skeletal muscle of offspring is affected by maternal consumption of high fat diet differently between newborns and infants

Pantaleão, Lucas Carminatti
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/11/2010 Português
Relevância na Pesquisa
37.10545%
A redução no desenvolvimento muscular de filhotes cujas mães foram submetidas ao consumo de dietas baseadas no padrão ocidental pode ser, ao menos em parte, explicada pela resistência periférica à insulina, condição na qual a atividade de proteínas relacionadas à via de sinalização intracelular sensível a esse hormônio encontra-se reduzida. A regulação positiva dessa via resulta no aumento da atividade do Alvo da Rapamicina em Mamíferos (mTOR) que atua como efetor positivo da taxa de tradução de RNAm e, consequentemente, da síntese proteica. Estudos que avaliam a atividade dessa proteína frente ao consumo crônico de dietas hiperlipídicas são escassos e controversos e, até o momento, não são conhecidos trabalhos que avaliaram esses marcadores em animais neonatos ou desmamados, provenientes de mães alimentadas com dieta hiperlipídica gestacional e pós-gestacional. O presente estudo objetiva avaliar o efeito do consumo de uma dieta hiperlipídica por ratas adultas sobre a morfologia e sobre a expressão e a fosforilação das proteínas que compõem a via de sinalização intracelular do mTOR no músculo esquelético da prole em dois momentos: nascimento e desmame. Para isso, inicialmente, 39 ratas foram distribuídas em dois grupos...

Análise comparativa da expressão imuno-histoquímica da via PI3K-AKT-mTOR em displasias epiteliais, lesões irritativas e carcinomas espinocelulares; Comparative analysis of the immunohistochemical expression of PI3K-AKT-mTOR in epithelial dysplasia, irritative lesions and squamous cell carcinomas

Martins, Fabiana Martins e
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 08/05/2013 Português
Relevância na Pesquisa
36.987754%
A leucoplasia é a mais comum das lesões potencialmente malignas (LPM) da mucosa bucal acometendo cerca de 2% da população. A via PI3K- AKT-mTOR, tem papel importante na carcinogênese em diversos tumores, incluindo o câncer de cabeça e pescoço e estudos têm apontado os inibidores do mTOR como promissores agentes de avaliação terapêutica. Desta forma, no presente estudo avaliamos a expressão imuno-histoquímica de lesões bucais diagnosticadas clinicamente como leucoplasias, comparando-as com carcinomas espinocelulares (CEC), hiperqueratoses irritativas (HI) e mucosa normal (MN). Foram avaliados 186 casos, divididos em 5 grupos tais como displasia epitelial de alto risco (DAR), displasia epitelial de baixo risco (DBR), CEC, HI e MN. Os casos foram retirados do arquivo do Serviço de Patologia Cirúrgica da Disciplina de Patologia Bucal da Faculdade de Odontologia da Universidade de São Paulo. As informações clínicas, relativas ao sexo e idade dos pacientes e localização das lesões foram compiladas. Todas as lesões selecionadas foram observadas ao HE por dois patologistas, ao microscópio de luz para confirmação dos diagnósticos. As proteínas pesquisadas incluiram: pAKT, pmTOR, pS6, e p4EBP1. A marcação dos diversos anticorpos foi quantificada com o auxílio da aquisição de imagens realizada com o uso de um fotomicroscópio. Na imagem capturada (aumento de 400x)...

Contribuição da via de sinalização IGF-I/Akt/mTOR na atrofia muscular desencadeada pela insuficiência cardíaca: influência do treinamento físico aeróbico; Contribution of IGF-I/Akt/mTOR signaling pathway to the muscular atrophy induced by heart failure: influence of aerobic exercise training

Bacurau, Aline Villa Nova
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/10/2013 Português
Relevância na Pesquisa
37.126433%
A insuficiência cardíaca (IC) é a via final comum da maioria das cardiomiopatias e outras doenças do aparelho circulatório. Considerando a prevalência crescente e a morbimortalidade associada representa um importante problema de saúde pública. Em quadros mais avançados, além do comprometimento funcional, portadores de IC apresentam perda de massa muscular excessiva que pode culminar em caquexia cardíaca; condição que contribui para o mau prognóstico e a mortalidade aumentadas. A massa muscular é regulada pelo balanço entre estímulos anabólicos e catabólicos. A quinase Akt vêm sendo considerando uma importante quinase na regulação do crescimento muscular por controlar o anabolismo proteico. Dessa forma, ativadores da Akt (IGF-I e insulina), bem como proteínas alvo da sinalização da Akt (mTOR e GSK3) são importantes mediadores na manutenção da massa muscular e podem ser regulados por estímulos metabólicos, nutricionais e mecânicos. Assim, o objetivo desse estudo foi avaliar a contribuição da via de sinalização IGF-I/Akt/mTOR na atrofia muscular desencadeada pela IC tanto em humanos quanto em modelo experimental, bem como o efeito do treinamento físico aeróbico (TFA). Nossos resultados demonstraram que em biópsias do vasto lateral de pacientes portadores de IC classe II houve redução na expressão de mRNA de todas as isoformas de IGF-I e na expressão das proteínas IGFBP-3...

Participação da via BDNF-TRkB-mTor do córtex pré-frontal medial ventral no efeito tipo antidepressivo induzido por inibidores da metilação do DNA; Participation BDNF-TrkB-mTOR pathway prefrontal medial ventral cortex in antidepressant-like effect induced by inhibitors of DNA methylation

Suavinha, Angélica Caroline Dutra Romano
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 24/04/2014 Português
Relevância na Pesquisa
37.09274%
Recentemente suspeitas de que mecanismos epigenéticos poderiam estar relacionados à fisiopatologia da depressão foram levantadas. Estudos recentes indicam que as alterações na transcrição gênica, induzidas por estresse ou por drogas antidepressivas, parecem envolver mecanismos epigenéticos. Nesse sentido, resultados preliminares de nosso grupo de pesquisa indicaram pioneiramente inibição global da metilação de DNA através da administração sistêmica do agente inibidor da DNA metiltransferase (DNMTs), 5-aza-2-deoxicitidina (5-azaD), induz efeito tipo-antidepressivo, dose-dependente, no modelo animal do nado forçado em ratos(Sales et al., 2011). O córtex pré-frontal medial ventral (CPFMv) é uma estrutura límbica intimamente relacionada com a neurobiologia da depressão. Evidências recentes indicam que o efeito tipo-antidepressivo aparece associado a aumento dos níveis da neurotrofina BDNF (brain derived neurotrophic factor) e de seu receptor TrkB no CPFMv, sendo a sinalização intracelular mediada pela ativação da proteína m-TOR. Contudo, não há evidências de que esses mecanismos moleculares estariam envolvidos nos efeitos induzidos pelos inibidores da metilação do DNA. Sabe-se, no entanto, que tanto o BDNF quanto TrkB têm sua expressão regulada por metilação do DNA. Diante disso...

Papel de mTOR na formação e reconsolidação da memória

Jobim, Paulo Fernandes Costa
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
Português
Relevância na Pesquisa
37.143047%
Novas informações assimiladas pelo sistema nervoso primeiramente ficam em um estado de labilidade para depois se estabilizarem através de um processo conhecido como consolidação, que envolve síntese de proteínas. Depois da reativação, uma memória previamente consolidada retorna ao seu estado de labilidade, e para que volte a ser estável, é necessário que haja novamente síntese de proteínas. Este segundo processo é chamado de reconsolidação. Recentemente os mecanismos moleculares e celulares envolvidos na regulação da síntese protéica relacionados à formação de memória de longa duração vêm sendo esclarecidos. A proteína alvo da rapamicina em mamíferos (mTOR) modula a plasticidade sináptica pela regulação da fosforilação de dois alvos: a proteína ribossomal S6K e a proteína de ligação 4E. A amígdala basolateral e o hipocampo dorsal são parte integrante do sistema neural envolvido na formação e expressão de diversos tipos de memórias. Estudos indicam que a via de sinalização da mTOR no hipocampo tem um papel importante na consolidação da memória de ratos submetidos a tarefa de esquiva inibitória e reconhecimento de objetos e na reconsolidação da memória de medo contextual condicionado. Contudo...

Phospho-mTOR in non-tumour and tumour bladder urothelium : pattern of expression and impact on urothelial bladder cancer patients

Afonso, Julieta; Longatto Filho, Adhemar; Silva, Vitor Moreira; Amaro, T.; Santos, L. L.
Fonte: Spandidos Publications Publicador: Spandidos Publications
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
36.951392%
Urothelial bladder carcinoma (UBC) is heterogeneous in its pathology and clinical behaviour. Evaluation of prognostic and predictive biomarkers is necessary, in order to produce personalised treatment options. The present study used immunohistochemistry to evaluate UBC sections containing tumour and non-tumour areas from 76 patients, for the detection of p-mTOR, CD31 and D2-40 (blood and lymphatic vessels identification, respectively). Of the non-tumour and tumour sections, 36 and 20% were scored positive for p-mTOR expression, respectively. Immunoexpression was observed in umbrella cells from non-tumour urothelium, in all cell layers from non-muscle-invasive (NMI) tumours (including expression in superficial cells), and in spots of cells from muscle-invasive (MI) tumours. Positive expression decreased from non-tumour to tumour urothelium, and from pT1/pTis to pT3/pT4 tumours; however, the few pT3/pT4 positive cases had worse survival rates, with 5-year disease-free survival being significantly lower. Angiogenesis occurrence was impaired in pT3/pT4 tumours that did not express p-mTOR. In conclusion, p-mTOR expression in non-tumour umbrella cells is likely a reflection of their metabolic plasticity, and extension to the inner layers of the urothelium in NMI tumours is consistent with an enhanced malignant potential. The expression in cell spots in a few MI tumours and absence of expression in the remaining tumours is intriguing and requires further research. Additional studies regarding the up- and downstream effectors of the mTOR pathway should be conducted

Akt and mTOR mediate programmed necrosis in neurons

Liu, Q; Qiu, J; Liang, M; Golinski, J; van Leyen, K; Jung, J E; You, Z; Lo, E H; Degterev, A; Whalen, M J
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.040996%
Necroptosis is a newly described form of regulated necrosis that contributes to neuronal death in experimental models of stroke and brain trauma. Although much work has been done elucidating initiating mechanisms, signaling events governing necroptosis remain largely unexplored. Akt is known to inhibit apoptotic neuronal cell death. Mechanistic target of rapamycin (mTOR) is a downstream effector of Akt that controls protein synthesis. We previously reported that dual inhibition of Akt and mTOR reduced acute cell death and improved long term cognitive deficits after controlled-cortical impact in mice. These findings raised the possibility that Akt/mTOR might regulate necroptosis. To test this hypothesis, we induced necroptosis in the hippocampal neuronal cell line HT22 using concomitant treatment with tumor necrosis factor α (TNFα) and the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone. TNFα/zVAD treatment induced cell death within 4 h. Cell death was preceded by RIPK1–RIPK3–pAkt assembly, and phosphorylation of Thr-308 and Thr473 of AKT and its direct substrate glycogen synthase kinase-3β, as well as mTOR and its direct substrate S6 ribosomal protein (S6), suggesting activation of Akt/mTOR pathways. Pretreatment with Akt inhibitor viii and rapamycin inhibited Akt and S6 phosphorylation events...

Incomplete inhibition of phosphorylation of 4E-BP1 as a mechanism of primary resistance to ATP-competitive mTOR inhibitors

Ducker, Gregory S.; Atreya, Chloe E.; Simko, Jeffry P.; Hom, Yun K.; Matli, Mary R.; Benes, Cyril H.; Hann, Byron; Nakakura, Eric K.; Bergsland, Emily K.; Donner, David B.; Settleman, Jeffrey; Shokat, Kevan M.; Warren, Robert S.
Fonte: Harvard University Publicador: Harvard University
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.951392%
The mammalian target of rapamycin (mTOR) regulates cell growth by integrating nutrient and growth factor signaling and is strongly implicated in cancer. But mTOR is not an oncogene, and which tumors will be resistant or sensitive to new ATP-competitive mTOR inhibitors now in clinical trials remains unknown. We screened a panel of over 600 human cancer cell lines to identify markers of resistance and sensitivity to the mTOR inhibitor PP242. RAS and PIK3CA mutations were the most significant genetic markers for resistance and sensitivity to PP242, respectively; colon origin was the most significant marker for resistance based on tissue type. Among colon cancer cell lines, those with KRAS mutations were most resistant to PP242, while those without KRAS mutations most sensitive. Surprisingly, cell lines with co-mutation of PIK3CA and KRAS had intermediate sensitivity. Immunoblot analysis of the signaling targets downstream of mTOR revealed that the degree of cellular growth inhibition induced by PP242 was correlated with inhibition of phosphorylation of the translational repressor 4E-BP1, but not ribosomal protein S6. In a tumor growth inhibition trial of PP242 in patient-derived colon cancer xenografts, resistance to PP242 induced inhibition of 4E-BP1 phosphorylation and xenograft growth was again observed in KRAS mutant tumors without PIK3CA co-mutation...

Lymphangiogenesis in Gastric Cancer regulated through Akt/mTOR-VEGF-C/VEGF-D axis

Chen, Hongxia; Guan, Runnian; Lei, Yupeng; Chen, Jianyong; Ge, Qi; Zhang, Xiaoshen; Dou, Ruoxu; Chen, Hongyuan; Liu, Hao; Qi, Xiaolong; Zhou, Xiaodong; Chen, Changyan
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.116587%
Background: Lymphangiogenesis plays a significant role in metastasis and recurrence of gastric cancer. There is no report yet focusing on the modulation of VEGF pathway and lymphangiogenesis of gastric cancer by targeting Akt/mTOR pathway. This study aims to demonstrate the relationship between Akt/mTOR pathway and VEGF-C/-D in gastric cancer. Methods: We collected surgically resected gastric adenocarcinoma specimens from 55 consented patients. Immunohistochemistry staining of p-Akt, p-mTOR, VEGF-C, VEGF-D were performed and scored by two independent pathologists. The results were presented as staining intensity and positive staining cell rate. We also measured lymphatic vessel density (LVD) by D2-40 staining. Different dosages of p-Akt inhibitor LY294002 (12.5 μM, 25 μM, 50 μM) and p-mTOR inhibitor Rapamycin (25 nM, 50 nM, 100 nM) were given to gastric cancer cell line SGC-7901 in vitro. The inhibition rate of cell growth was tested by MTT at 24 h, 48 h and 72 h, respectively and protein expressions of Akt, p-Akt, mTOR, p-mTOR, VEGF-C and VEGF-D were examined by Western blot. Results: The positive staining rates of p-Akt, p-mTOR, VEGF-C and VEGF-D in 55 gastric cancer clinical specimens were 74.54%, 85.45%, 72.73% and 58.18%. p-Akt and p-mTOR were positively correlated with VEGF-C and VEGF-D (p < 0.01). The LVD increased with incremental tendency of staining intensity of p-Akt...

Multipoint targeting of the PI3K/mTOR pathway in mesothelioma

Zhou, S; Liu, L; Li, H; Eilers, G; Kuang, Y; Shi, S; Yan, Z; Li, X; Corson, J M; Meng, F; Zhou, H; Sheng, Q; Fletcher, J A; Ou, W-B
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.951392%
Background: Mesothelioma is a notoriously chemotherapy-resistant neoplasm, as is evident in the dismal overall survival for patients with those of asbestos-associated disease. We previously demonstrated co-activation of multiple receptor tyrosine kinases (RTKs), including epidermal growth factor receptor (EGFR), MET, and AXL in mesothelioma cell lines, suggesting that these kinases could serve as novel therapeutic targets. Although clinical trials have not shown activity for EGFR inhibitors in mesothelioma, concurrent inhibition of various activated RTKs has pro-apoptotic and anti-proliferative effects in mesothelioma cell lines. Thus, we hypothesised that a coordinated network of multi-RTK activation contributes to mesothelioma tumorigenesis. Methods: Activation of PI3K/AKT/mTOR, Raf/MAPK, and co-activation of RTKs were evaluated in mesotheliomas. Effects of RTK and downstream inhibitors/shRNAs were assessed by measuring mesothelioma cell viability/growth, apoptosis, activation of signalling intermediates, expression of cell-cycle checkpoints, and cell-cycle alterations. Results: We demonstrate activation of the PI3K/AKT/p70S6K and RAF/MEK/MAPK pathways in mesothelioma, but not in non-neoplastic mesothelial cells. The AKT activation...

NVP-BEZ235, a dual pan class I PI3 kinase and mTOR inhibitor, promotes osteogenic differentiation in human mesenchymal stromal cells

Martin, S.; Fitter, S.; Bong, L.; Drew, J.; Gronthos, S.; Shepherd, P.; Zannettino, A.
Fonte: Amer Soc Bone & Mineral Res Publicador: Amer Soc Bone & Mineral Res
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
Relevância na Pesquisa
36.951392%
Osteoblasts are bone-forming cells derived from mesenchymal stromal cells (MSCs) that reside within the bone marrow. In response to a variety of factors, MSCs proliferate and differentiate into mature, functional osteoblasts. Several studies have shown previously that suppression of the PI3K and mTOR signaling pathways in these cells strongly promotes osteogenic differentiation, which suggests that inhibitors of these pathways may be useful as anabolic bone agents. In this study we examined the effect of BEZ235, a newly developed dual PI3K and mTOR inhibitor currently in phase I-II clinical trials for advanced solid tumors, on osteogenic differentiation and function using primary MSC cultures. Under osteoinductive conditions, BEZ235 strongly promotes osteogenic differentiation, as evidenced by an increase in mineralized matrix production, an upregulation of genes involved in osteogenesis, including bone morphogenetic proteins (BMP2, -4, and -6) and transforming growth factor β1 (TGF-β1) superfamily members (TGFB1, TGFB2, and INHBE), and increased activation of SMAD signaling molecules. In addition, BEZ235 enhances de novo bone formation in calvarial organotypic cultures. Using pharmacologic inhibitors to delineate mechanism, our studies reveal that suppression of mTOR and...

Differing effects of rapamycin and mTOR kinase inhibitors on protein synthesis

Huo, Y.; Iadevaia, V.; Proud, C.
Fonte: Portland Press Publicador: Portland Press
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
37.040996%
mTOR (mammalian target of rapamycin) forms two distinct types of complex, mTORC (mTOR complex) 1 and 2. Rapamycin inhibits some of the functions of mTORC1, whereas newly developed mTOR kinase inhibitors interfere with the actions of both types of complex. We have explored the effects of rapamycin and mTOR kinase inhibitors on general protein synthesis and, using a new stable isotope-labelling method, the synthesis of specific proteins. In HeLa cells, rapamycin only had a modest effect on total protein synthesis, whereas mTOR kinase inhibitors decreased protein synthesis by approx. 30%. This does not seem to be due to the ability of mTOR kinase inhibitors to block the binding of eIFs (eukaryotic initiation factors) eIF4G and eIF4E. Analysis of the effects of the inhibitors on the synthesis of specific proteins showed a spectrum of behaviours. As expected, synthesis of proteins encoded by mRNAs that contain a 5′-TOP (5′-terminal oligopyrimidine tract) was impaired by rapamycin, but more strongly by mTOR kinase inhibition. Several proteins not known to be encoded by 5′-TOP mRNAs also showed similar behaviour. Synthesis of proteins encoded by ‘non-TOP’ mRNAs was less inhibited by mTOR kinase inhibitors and especially by rapamycin. The implications of our findings are discussed.; Yilin Huo...

Regulation of Potassium Channels through mTOR and PDK1 in Dendritic and Mast Cells; Regulation von Kalium-Kanälen durch mTOR und PDK1 in Dendritischen und Mast-Zellen

Tyan, Leonid
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
37.143047%
Dendritic cells are antigen-presenting cells, central for the development of optimal T cell immunity, that are able to initiate primary immune responses and to establish immunological memory. Mast cells are tissue-based effector cells in allergic diseases, playing a central role in the propagation of IgE-dependent allergic reactions, such as allergic rhinitis, asthma, anaphylaxis and delayed hypersensitivity reactions. Upon stimulation of IgE receptors , mast cells release granules containing several mediators including histamine and cytokines, which regulate responses of other inflammatory cells. Dendritic and mast cell functions are regulated by phosphatidylinositol-3 (PI3) kinase signalling pathway.. The PI3 kinase is partially effective in dendritic and mast cells through alteration of their ion channel activity. Both PI3 kinase on the one hand and ion channels on the other hand are important for the regulation of mast and dendritic cell functions. However, little is known about downstream elements of the PI3 kinase that regulate ion channels in those cells. In the present project the question was addressed whether two PI3 kinase downstream targets, phosphoinositide-dependent kinase 1 (PDK1) and mammalian target of rapamycine (mTOR)...

Translational inhibitory conditions and mechanistic target of rapamycin (mTOR) protein expression – an internal ribosome entry site (IRES) solves the problem

Marques-Ramos, Ana; Menezes, Juliane; Lacerda, Rafaela; Teixeira, Alexandre; Romão, Luísa
Fonte: Instituto Nacional de Saúde Doutor Ricardo Jorge Publicador: Instituto Nacional de Saúde Doutor Ricardo Jorge
Tipo: Conferência ou Objeto de Conferência
Publicado em 21/07/2014 Português
Relevância na Pesquisa
37.078105%
Regulation of mRNA translation plays a major role in controlling gene expression, since it allows rapid cellular responses to external stimuli. Translational control can be transcript-specific via cis-acting elements, such as internal ribosome entry sites (IRESs). mRNA translation initiation driven by IRES elements is independent of some canonical initiation factors that are inhibited by cellular stresses or in some physiological/pathophysiologic settings. Accordingly, IRES-dependent translation allows continued protein synthesis in conditions of global canonical mRNA translation inhibition. The mechanistic target of rapamycin (mTOR) is a conserved serine/threonine kinase that senses cellular nutrient- and energy- status, acting namely on the protein synthesis machinery. Major advances are emerging regarding the effects and regulators of mTOR signaling pathway, however, regulation of mTOR gene expression, specifically at the translational level, is not well known. Here, it is shown that the 5’ untranslated region (5’UTR) of the human mTOR mRNA contains an IRES element that allows cap-independent translation of mTOR. In addition, it is demonstrated that IRES-dependent translation of mTOR is stimulated by hypoxia with associated eIF2α phosphorylation. The anti- and pro-apoptotic outcomes of the response to endoplasmic reticulum (ER) stress also stimulate mTOR IRES activity...

Identification of an IRES element in the human mTOR transcript: its structural and functional features

Marques-Ramos, Ana; Menezes, Juliane; Lacerda, Rafaela; Teixeira, Alexandre; Romão, Luísa
Fonte: Instituto Nacional de Saúde Doutor Ricardo Jorge Publicador: Instituto Nacional de Saúde Doutor Ricardo Jorge
Tipo: Conferência ou Objeto de Conferência
Publicado em 03/06/2014 Português
Relevância na Pesquisa
37.126433%
Mammalian target of rapamycin (mTOR) is a conserved serine/threonine kinase that integrates signals from the cellular nutrient- and energy-status, acting namely on the protein synthesis machinery. Deregulation of mTOR signaling is implicated in major diseases, such as cancer, mainly due to its role in regulating protein synthesis. The main mTOR targets are proteins responsible for ribosome recruitment to the mRNA, thus, a specific inhibitor of mTOR, for example rapamycin, leads to global inhibition of translation. Major advances are emerging regarding the regulators and effects of mTOR signaling pathway, however, regulation of mTOR gene expression, is not well known. Knowing that in stress conditions such as hypoxia, overall protein synthesis is reduced, but synthesis of mTOR protein is not inhibited, we hypothesized that mTOR 5’UTR harbors an IRES allowing cap-independent synthesis of mTOR protein in stress conditions. By using dicistronic reporter plasmids we have tested and confirmed this hypothesis. In addition, we have shown that IRES-dependent translation of mTOR is stimulated by hypoxia with associated eIF2α phosphorylation, in a manner that is independent of HIF1α induction per se. The anti- and pro-apoptotic outcomes of the unfolded protein response induced by endoplasmic reticulum stress also stimulates mTOR IRES activity...

mTOR direct interactions with Rheb-GTPase and raptor: sub-cellular localization using fluorescence lifetime imaging

Yadav, R.; Burgos, P.; Parker, A.; Iadevaia, V.; Proud, C.; Allen, R.; O'Connell, J.; Jeshtadi, A.; Stubbs, C.; Botchway, S.
Fonte: Biomed Central Ltd Publicador: Biomed Central Ltd
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
Relevância na Pesquisa
37.078105%
Background: The mammalian target of rapamycin (mTOR) signalling pathway has a key role in cellular regulation and several diseases. While it is thought that Rheb GTPase regulates mTOR, acting immediately upstream, while raptor is immediately downstream of mTOR, direct interactions have yet to be verified in living cells, furthermore the localisation of Rheb has been reported to have only a cytoplasmic cellular localization. Results: In this study a cytoplasmic as well as a significant sub-cellular nuclear mTOR localization was shown , utilizing green and red fluorescent protein (GFP and DsRed) fusion and highly sensitive single photon counting fluorescence lifetime imaging microscopy (FLIM) of live cells. The interaction of the mTORC1 components Rheb, mTOR and raptor, tagged with EGFP/DsRed was determined using fluorescence energy transfer-FLIM. The excited-state lifetime of EGFP-mTOR of ~2400 ps was reduced by energy transfer to ~2200 ps in the cytoplasm and to 2000 ps in the nucleus when co-expressed with DsRed-Rheb, similar results being obtained for co-expressed EGFP-mTOR and DsRed-raptor. The localization and distribution of mTOR was modified by amino acid withdrawal and re-addition but not by rapamycin. Conclusions: The results illustrate the power of GFP-technology combined with FRET-FLIM imaging in the study of the interaction of signalling components in living cells...

A role for mammalian target of rapamycin (mTOR) pathway in non alcoholic steatohepatitis related-cirrhosis

KUBRUSLY, Marcia Saldanha; CORREA-GIANNELLA, Maria Lucia; BELLODI-PRIVATO, Marta; SA, Sandra Valeria de; OLIVEIRA, Claudia Pinto Marques Souza de; SOARES, Ibere Cauduro; WAKAMATSU, Alda; ALVES, Venancio Avancini Ferreira; GIANNELLA-NETO, Daniel; BACCHELLA
Fonte: F HERNANDEZ Publicador: F HERNANDEZ
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.987754%
Non-alcoholic fatty liver disease (NAFLD) encompasses the whole spectrum of steatosis, nonalcoholic steatohepatitis (NASH), and NASH-related cirrhosis (NASH/Cir). Although molecular advances have been made in this field, the pathogenesis of NAFLD is not completely understood. The gene expression profiling associated to NASH/Cir was assessed, in an attempt to better characterize the pathways involved in its etiopathogenesis. Methods: In the first step, we used cDNA microarray to evaluate the gene expression profiles in normal liver (n=3) and NASH/Cir samples (n=3) by GeneSifter (TM) analysis to identify differentially expressed genes and biological pathways. Second, tissue microarray was used to determine immunohistochemical expression of phosphorylated mTOR and 4E-BP1 in 11 normal liver samples, 10 NASH/Cir samples and in 37 samples of cirrhosis of other etiologies to further explore the involvement of the mTOR pathway evidenced by the gene expression analysis. Results: 138 and 106 genes were, respectively, up and down regulated in NASH/Cir in comparison to normal liver. Among the 9 pathways identified as significantly modulated in NASH/Cir, the participation of the mTOR pathway was confirmed, since expression of cytoplasmic and membrane phospho-mTOR were higher in NASH/Cir in comparison to cirrhosis of other etiologies and to normal liver. Conclusions: Recent findings have suggested a role for the cellular ""nutrient sensor"" mTOR in NAFLD and the present study corroborates the participation of this pathway in NASH/Cir. Phospho-mTOR evaluation might be of clinical utility as a potential marker for identification of NASH/Cir in cases mistakenly considered as cryptogenic cirrhosis owing to paucity of clinical data.

The Role of Autophagy and Translation Initiation Factors in Overcoming Resistance to mTOR Inhibitors in Prostate Cancer.

Herbert, James Taylor
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2013 Português
Relevância na Pesquisa
37.09274%

Castration resistant prostate cancer (CRPC) causes significant morbidity and mortality around the world and improving treatment options for patients with CRPC is a major concern for biomedical research. Because of the importance of activating mutations in the PI3K/AKT/mTOR pathway in prostate cancer, several mTOR inhibitors have been tested for efficacy in CRPC but despite promising preclinical findings, the results of clinical trials have been disappointing. The findings of several groups, including a clinical trial of RAD001 conducted at Duke, suggest that feedback upregulation of PI3K and autophagy may be potential mechanisms for resistance of CRPC to mTOR inhibitor therapy.

The main goal of this dissertation was to explore these mechanisms in vitro and to determine if combinations of PI3K inhibitors and different classes of mTOR inhibitors can overcome resistance to mTOR inhibitor monotherapy. In particular, we used immunoblotting, reverse phase protein microarrays, polysome profile analysis, cell cycle analysis, and several techniques for determining cell survival and proliferation to explore the differences in survival, proliferation, autophagy, and activity of the AKT, translation initiation, and autophagy cell signaling networks between prostate cancer cell lines treated with different combinations of mTOR and PI3K inhibitors. Our findings revealed that the combination of PI3K and mTOR inhibition leads to a synergistic inhibition of prostate cancer cell survival and cytostasis that is correlated decreased translation rates...