Análise global do transcriptoma de pequenos RNAs e RNAs mensageiros durante a Interação Macrófago -Trypanosoma cruzi

• Ano de defesa: 2016
• Autor(a) principal: André Nicolau Aquime Gonçalves
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Bioinformática; Trypanosoma cruz; MicroRNAs; Genes; Sequência de Bases
• Link de acesso: http://hdl.handle.net/1843/BUOS-B97EXG

Chagas disease is caused by the intracellular parasite Trypanosoma cruzi, which is capable of infecting several cell types. The initial interaction between parasite and host involves the activation of pathways responsible for the internalization of the parasite, the innate immune response of the host and the fight against intracellular parasites. Several changes in gene expression occur in the host cell in response to the pathogen and vice versa. Interfering RNA pathways (RNAi) are related to posttranscriptional regulation of gene expression mediated by small non-coding RNAs such as microRNAs (miRNAs), which allow fine-tuning of various biological responses and are altered in parasitic infections. Macrophages infected with Leishmania sp. or Toxoplasma sp. has the altered expression of miRNAs that regulate the response to these parasites. To date, there is no description of the role of miRNAs during Trypanosoma cruzi infection in murine macrophages. In this work, we performed the sequencing of small RNAs from murine macrophages infected with the parasite Trypanosoma cruzi at 2, 4, 8 and 48 hours after infection to evaluate the general expression of the transcriptome of small RNAs, especially the host miRNAs. Expression of the proinflammatory cytokine TNF- was evaluated as an indicator of the innate immune response during infection, as well as the growth of intracellular parasites. There were no qualitative changes in the profile of small RNAs derived from the genome of the parasite throughout the infection. In contrast, among the small host RNAs, we observed the differential expression of several miRNAs between the times of 2 and 48 hours. Of the 18 miRNAs that showed differential expression at some time of infection, only 1 was expressed positively in at least two analyzed times, miR-34c-5p. We identified the predicted and validated targets for the miRNAs differentially expressed by the TargetScan tool and the StarBase database, and used the targets found in both for the study of miRNAs functions. The enrichment analysis of target mRNAs for biological pathways suggests that miRNAs are related to pathways such as TGF- signaling, Smads transcriptional activity, PI3K signaling cascade, signaling of cell death via JNK as well as the activation of NFKB via TRAF6. The miR-34c-5p showed significant positive regulation throughout the infection and validated the expression by RT-qPCR. Analysis of miR-34c-5p target mRNAs showed enrichment for biological processes as apoptosis response and Notch signaling. As the miRNAs act by regulating the stability of their target mRNAs, the macrophage transcriptome after 4 and 8 hours of infection was sequenced and analyzed. In all, 274 mRNAs were regulated: 33 were down-regulated and 241 were down-regulated at any of the times analyzed. However, there was no direct correlation, either positive or negative, between the miRNA targets differentially expressed during infection and their expression in the transcriptome. In spite of this, we observed the intersection of enriched biological pathways for the mRNAs targets of the differentially expressed miRNAs and biological pathways enriched for the mRNAs differentially expressed in the transcriptome. Enriched biological pathways were Rho GTPases signaling, membrane transport, cell cycle control, Notch signaling and transport and modification by the Golgi complex. Thus, the miRNAs induced by T. cruzi infection in macrophages are probably involved in the fine-tuning of activities of the biological pathways important in the response to infection and may act as indirect regulators of the components of these pathways. As a future perspective, differentially expressed miRNAs will be blocked and evaluated for their impact on T. cruzi infection response in murine macrophages.