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Id: lil-560969
Autor: Castaño, Diana; Rojas, Mauricio.
Título: Alteraciones en el reclutamiento y activación de proteínas Rab durante la infección micobacteriana: [revisão] / Alterations in recruitment and activation of Rab proteins during mycobacterial infection: [review]
Fonte: Biomédica (Bogotá);30(2):283-308, jun. 2010. ilus.
Idioma: es.
Resumo: En el fagosoma, Mycobacterium spp. altera la activación y reclutamiento de diferentes proteínas “del gen Ras de cerebro de rata”, comúnmente conocidas como Rab. En este manuscrito se revisa una serie de reportes que han demostrado que los fagosomas que contienen micobacterias tienen una expresión mayor y sostenida de Rab5, Rab11, Rab14 y Rab22a, y menor o ninguna expresión de Rab7, Rab9 y Rab6. Esto se correlaciona con aumento de la fusión de estos fagosomas con endosomas tempranos y de reciclaje, lo que les permite mantener ciertas características de compartimentos tempranos, permite que las bacterias obtengan acceso a nutrientes y previene la activación de mecanismos contra la micobacteria. La expresión de mutantes constitutivamente activos de las Rab de endosomas tempranos impide la maduración de fagosomas que contienen esferas de látex o micobacterias inactivadas por calor. Mientras que su silenciamiento, mediante ARN de interferencia o mediante dominantes negativos, induce la maduración de fagosomas micobacterianos. Los mecanismos exactos por los que las micobacterias alteran la dinámica de expresión de estas GTPasas, afectando la maduración fagolisosómica, no se han establecido. El problema podría explicarse por defectos en el reclutamiento de las proteínas que interactúan con Rab, como la cinasa-3 del fosfatidilinositol y el antígeno endosómico temprano 1. La identificación de los mecanismos empleados por Mycobacterium spp. para interrumpir el ciclo de activación de las Rab, será esencial para comprender la fisiopatología de la infección micobacteriana y útil como posibles blancos farmacológicos.

At the phagosome level, Mycobacterium spp. alters activation and recruitment of several “Ras gene from rat brain” proteins, commonly known as Rab. Mycobacterial phagosomes have a greater and sustained expression of Rab5, Rab11, Rab14 and Rab22a, and lowered or no expression of Rab7, Rab9 and Rab6. This correlates with increased fusion of the phagosomes with early and recycling endosomes acquiring some features of early phogosomes, allowing the bacteria to gain access to nutrients and preventing the activation of anti-mycobacterial mechanisms. The expression of constitutively active mutants of Rab from the early stage endosomes prevents the maturation of phagosomes containing latex beads or heat-inactivated mycobacteria. Silencing of these mutants by interference RNA or dominant negative forms induces the maturation of mycobacterial phagosomes. The mechanisms have not been established by which mycobacteria alter the expression of these GTPases and thereby shift the phagolysosomal maturation. The problem can be explained by alterations in the recruitment of proteins that interact with Rab, such as phosphoinositide 3-kinases and early endosomal antigen 1. Identifying the mechanisms used by Mycobacterium spp. to disrupt the cycle of Rab activation will be essential to understand the pathophysiology of mycobacterial infections and usefully to potential drug targets.
Descritores: Mycobacterium tuberculosis
Fagossomos
Proteínas rab de Ligação ao GTP
Tuberculose
-Endossomos
Proteínas SNARE
Tipo de Publ: Revisão
Responsável: CO42.1 - Biblioteca Nacional de Salud José Celestino Mutis


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Carneiro, Everardo M
Boschero, Antonio C
Texto completo
Id: lil-437387
Autor: Cunha, Daniel A; Amaral, Maria E. C; Carvalho, Carolina Pf; Collares-Buzato, Carla B; Carneiro, Everardo M; Boschero, Antonio C.
Título: Increased expression of SNARE proteins and synaptotagmin IV in islets from pregnant rats and in vitro prolactin-treated neonatal islets
Fonte: Biol. Res;39(3):555-566, 2006. ilus, tab.
Idioma: en.
Projeto: Brazilian foundations FAPESP, CAPES; . CNPq/ PRONEX.
Resumo: During pregnancy and the perinatal period of life, prolactin (PRL) and other lactogenic substances induce adaptation and maturation of the stimulus-secretion coupling system in pancreatic â-cells. Since the SNARE molecules, SNAP-25, syntaxin 1, VAMP-2, and synaptotagmins participate in insulin secretion, we investigated whether the improved secretory response to glucose during these periods involves alteration in the expression of these proteins. mRNA was extracted from neonatal rat islets cultured for 5 days in the presence of PRL and from pregnant rats (17th-18th days of pregnancy) and reverse transcribed. The expression of genes was analyzed by semi-quantitative RT-PCR assay. The expression of proteins was analyzed by Western blotting and confocal microscopy. Transcription and expression of all SNARE genes and proteins were increased in islets from pregnant and PRL-treated neonatal rats when compared with controls. The only exception was VAMP-2 production in islets from pregnant rats. Increased mRNA and protein expression of synaptotagmin IV, but not the isoform I, also was observed in islets from pregnant and PRL-treated rats. This effect was not inhibited by wortmannin or PD098059, inhibitors of the PI3-kinase and MAPK pathways, respectively. As revealed by confocal laser microscopy, both syntaxin 1A and synaptotagmin IV were immunolocated in islet cells, including the insulin-containing cells. These results indicate that PRL modulates the final steps of insulin secretion by increasing the expression of proteins involved in membrane fusion.
Descritores: Regulação da Expressão Gênica no Desenvolvimento/genética
Insulina
Ilhotas Pancreáticas
Prolactina/farmacologia
Proteínas SNARE/genética
Sinaptotagminas/genética
-Animais Recém-Nascidos
Western Blotting
Eletroforese em Gel de Poliacrilamida
Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos
Immunoblotting
Imunoquímica
Insulina/genética
Ilhotas Pancreáticas/efeitos dos fármacos
Ilhotas Pancreáticas/embriologia
Microscopia Confocal
Reação em Cadeia da Polimerase Via Transcriptase Reversa
RNA Mensageiro/análise
Proteínas SNARE/metabolismo
/genética
SYNAPTOSOMAL-ASSOCIATED PROTEIN ABORTION, SPONTANEOUS/genética
/metabolismo
SYNAPTOSOMAL-ASSOCIATED PROTEIN ABORTION, SPONTANEOUS/metabolismo
Sinaptotagminas/metabolismo
Sintaxina 1/genética
Sintaxina 1/metabolismo
/genética
VESICLE-ASSOCIATED MEMBRANE PROTEIN TEMEFOS/genética
/metabolismo
VESICLE-ASSOCIATED MEMBRANE PROTEIN TEMEFOS/metabolismo
Limites: Animais
Feminino
Gravidez
Ratos
Responsável: BR1.1 - BIREME



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