RESUMO
The horizontal transfer of Trypanosoma cruzi mitochondrial minicircle DNA to the genomes of naturally infected humans may play an important role in the pathogenesis of Chagas disease. Minicircle integrations within LINE-1 elements create the potential for foreign DNA mobility within the host genome via the machinery associated with this retrotransposon. Here we document integration of minicircle DNA fragments in clonal human macrophage cell lines and their mobilization over time. The movement of an integration event in a clonal transfected cell line was tracked at three months and three years post-infection. The minicircle sequence integrated into a LINE-1 retrotransposon; one such foreign fragment subsequently relocated to another genomic location in association with associated LINE-1 elements. The p15 locus was altered at three years as a direct effect of minicircle/LINE-1 acquisition, resulting in elimination of p15 mRNA. Here we show for the first time a molecular pathology stemming from mobilization of a kDNA/LINE-1 mutation. These genomic changes and detected transcript variations are consistent with our hypothesis that minicircle integration is a causal component of parasite-independent, autoimmune-driven lesions seen in the heart and other target tissues associated with Chagas disease.
Assuntos
Humanos , Animais , DNA de Cinetoplasto/genética , Expressão Gênica/genética , Elementos Nucleotídeos Longos e Dispersos/genética , Retroelementos/genética , Trypanosoma cruzi/genética , Linhagem Celular/parasitologia , Transferência Genética Horizontal , Interações Hospedeiro-Parasita/genética , Macrófagos/parasitologia , Trypanosoma cruzi/fisiologiaRESUMO
The horizontal transfer of Trypanosoma cruzi mitochondrial minicircle DNA to the genomes of naturally infected humans may play an important role in the pathogenesis of Chagas disease. Minicircle integrations within LINE-1 elements create the potential for foreign DNA mobility within the host genome via the machinery associated with this retrotransposon. Here we document integration of minicircle DNA fragments in clonal human macrophage cell lines and their mobilization over time. The movement of an integration event in a clonal transfected cell line was tracked at three months and three years post-infection. The minicircle sequence integrated into a LINE-1 retrotransposon; one such foreign fragment subsequently relocated to another genomic location in association with associated LINE-1 elements. The p15 locus was altered at three years as a direct effect of minicircle/LINE-1 acquisition, resulting in elimination of p15 mRNA. Here we show for the first time a molecular pathology stemming from mobilization of a kDNA/LINE-1 mutation. These genomic changes and detected transcript variations are consistent with our hypothesis that minicircle integration is a causal component of parasite-independent, autoimmune-driven lesions seen in the heart and other target tissues associated with Chagas disease.
Assuntos
DNA de Cinetoplasto/genética , Expressão Gênica/genética , Elementos Nucleotídeos Longos e Dispersos/genética , Retroelementos/genética , Trypanosoma cruzi/genética , Animais , Sequência de Bases , Linhagem Celular/parasitologia , Transferência Genética Horizontal , Interações Hospedeiro-Parasita/genética , Humanos , Macrófagos/parasitologia , Dados de Sequência Molecular , Trypanosoma cruzi/fisiologiaRESUMO
We demonstrate the genetic transfer of DNA between eukaryotes from different kingdoms. The mitochondrial kinetoplast DNA (kDNA) of the intracellular parasite Trypanosoma cruzi is transferred to human patients with Chagas disease. This transfer was reproduced experimentally in rabbits and chickens. The kDNA is integrated into the host genome. In the human chromosomes, five loci were identified as integration sites, and the beta-globin locus and LINE-1 retrotransposons were frequently targeted. Short repeated sequences in the parasite and the target host DNAs favor kDNA integration by homologous recombination. Introduced kDNA was present in offspring of chronically infected rabbits and in chickens hatched from T. cruzi-inoculated eggs. kDNA incorporated into the chicken germline was inherited through the F2 generation in the absence of persistent infection. kDNA integration represents a potential cause for the autoimmune response that develops in a percentage of chronic Chagas patients, which can now be approached experimentally.