RESUMO
The life cycle of the protozoan parasite Trypanosoma cruzi comprises rounds of proliferative cycles and differentiation in distinct host environments. Ras GTPases are molecular switches that play pivotal regulatory functions in cell fate. Rjl is a novel GTPase with unknown function. Herein we show that TcRjl blocks in vivo cell differentiation. The forced expression of TcRjl leads to changes in the overall tyrosine protein phosphorylation profile of parasites. TcRjl expressing parasites sustained DNA synthesis regardless the external stimuli for differentiation. Heterologous expression in the Drosophila melanogaster genetic system strongly suggests a role from TcRjl protein in RTK-dependent pathways and MAPK activation.
Assuntos
Proteínas Monoméricas de Ligação ao GTP/metabolismo , Proteínas de Protozoários/metabolismo , Trypanosoma cruzi/enzimologia , Animais , Animais Geneticamente Modificados , Drosophila melanogaster/enzimologia , Drosophila melanogaster/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Regulação Enzimológica da Expressão Gênica , Genes de Protozoários , Sistema de Sinalização das MAP Quinases , Proteínas Monoméricas de Ligação ao GTP/genética , Fenótipo , Proteínas de Protozoários/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Trypanosoma cruzi/genética , Trypanosoma cruzi/crescimento & desenvolvimentoRESUMO
The protozoan parasite Trypanosoma cruzi, the etiological agent of Chagas Disease, undergoes through a complex life cycle where rounds of cell division and differentiation occur initially in the gut of triatominae vectors and, after transmission, inside of infected cells in vertebrate hosts. Members of the Ras superfamily of GTPases are molecular switches which play pivotal regulatory functions in cell growth and differentiation. We have previously described a novel GTPase in T. cruzi, TcRjl, which belongs to the RJL family of Ras-related GTP binding proteins. Here we show that most of TcRjl protein is found bound to GTP nucleotides and may be locked in this stage. In addition, we show that TcRjl is located close to the kinetoplast, in a region corresponding possibly to flagellar pocket of the parasite and the expression of a dominant-negative TcRjl construct (TcRjlS37N) displays a significative growth phenotype in reduced serum medium. Remarkably, overexpression of TcRjl inhibits differentiation of epimastigotes to trypomastigote forms and promotes the accumulation of intermediate differentiation stages. Our data suggest that TcRjl might play a role in the control of the parasite growth and differentiation.
