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Doctoral Thesis
DOI
Document
Author
Full name
Maria Amélia Villela Oliva Dotta
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2011
Supervisor
Committee
Thiemann, Otavio Henrique (President)
Degrave, Wim Maurits Sylvain
Navarro, Marcos Vicente de Albuquerque Salles
Sabbaga, Maria Carolina Quartim Barbosa Elias
Winter, Lucile Maria Floeter
Title in Portuguese
Estudos com a poli-A binding protein 1 de Trypanosoma brucei sugerem nova função nos eventos de splicing e exportação nuclear
Keywords in Portuguese
Splicing
Poli-A binding protein
Poliadenilação
Abstract in Portuguese
Protozoários do gênero Trypanosoma infectam milhões de pessoas todo ano e coletivamente contribuem muito para as misérias humanas, pois são causa de muitas das doenças negligenciadas tropicais. Várias vias metabólicas essenciais são encontradas nesses parasitas tornando-os particularmente atrativos para investigações moleculares. Mecanismos de controle pós-transcricional tem sido alvo de estudo por sua peculiaridade nesses organismos. Nesse cenário, proteínas da classe das poli-A-binding proteins (PABP) possuem função no início da tradução, turnover do mRNA e interação com o 5´-CAP. Nesse trabalho foi identificada a homóloga poli-A binding protein 1 (PABP1) de Trypanosoma brucei. O silenciamento do gene pabp1 revelou que a ausência da proteína é letal ao parasita, comprovando sua essencialidade nesse organismo. Da mesma maneira, na ausência da proteína observou-se erro no processamento do mRNA sugerindo possível função nos eventos de cis e trans splicing. Sua localização subcelular foi avaliada indicando localização citoplasmática, bem como o são suas homólogas. No citoplasma, a proteína apresenta-se em estrutura reticulada, co-localizada com proteínas de retículo endoplasmático. Porém, sob estresse induzido a proteína relocaliza para o compartimento nuclear, indicando ser uma proteína com trânsito núcleo-citoplasma ainda não demonstrada na literatura. As funções identificadas sugerem a existência de um sub-complexo a 3´ do mRNA que acopla poliadenilação e splicing. Além disso, a relocalização nuclear parece ocorrer em resposta a estímulo externo, sugerindo que a relocalização do mRNA para o núcleo pode ser uma estratégia da célula para modular sua resposta gênica frente a variações do ambiente.
Title in English
Studies with Trypanosoma brucei poly(A)-binding protein 1 suggest a novel function in splicing and nuclear export events
Keywords in English
Splicing
Poly(A)-binding protein
Polyadenilation
Abstract in English
Protozoa of the genus Trypanosoma infect millions of people every year and collectively contribute to the human misery by causing several neglected tropical diseases. Several intriguing molecular pathways are found in these parasites also, rendering them particularly attractive for biochemical investigation. This unique eukaryotic cells lack mechanisms to control gene expression at the transcriptional level, they mostly control protein synthesis by posttranscriptional regulation process. Several RNAs and proteins are involved in this process, including poly(A) binding proteins. The poly(A)- binding protein of eukaryotes plays a role in polyadenylation, translation initiation and metabolism of mRNA. In this work the poly(A) binding protein 1 (PABP1) was identified in Trypanosoma brucei. Depletion of TbPABP1 showed its essential role in the procyclic form of the parasite. Immunofluorescence assays showed localization in the cytosolic compartment despite of its functions in cis and trans splicing as shown by RNA analysis of cells free from PABP1. As it was shown in the homologs, PABP1 it´s not only a cytosolic protein but it shuttles between the nucleus and the cytoplasm. Together with the literature, these results suggest an active complex in the 3´ end of the mRNA which works in synchrony with the splicing and capping machinery implying PABP1 as possible link between these processes.
 
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Publishing Date
2012-03-06
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • Costa, F. C., et al. Molecular characteriza of a Trypanossoma brucei poly (A-) binding protein. In XXVI Annual Meeting of the Brazilia Society of Protozoology and XXXVII Annual Meeting on Basic Research in Chagas' Disease, Foz do Iguaçu, 2010. XXVI Annual Meeting of the Brazilia Society of Protozoology and XXXVII Annual Meeting on Basic Research in Chagas' Disease., 2010. Resumo.
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