Efeito do heme no metabolismo de glicose das formas epimastigotas de Trypanosoma cruzi: uma abordagem bioquímica e metabolômica

• Autor(a) principal: Vieira, Carolina Silva Dias
• Data de Publicação: 2020
• Outros Autores: [e-mail]
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/18478
• topic: Trypanosoma cruzi; Heme; Metabolism; Trypanosoma cruzi; Heme; Metabolismo; CIENCIAS BIOLOGICAS::BIOQUIMICA::BIOQUIMICA DOS MICROORGANISMOS

Heme is a molecule present in high amounts in the insect vector’s intestine and influences the metabolism of Trypanosoma cruzi epimastigotes. This porphyrin induces proliferation, stimulates physiological changes and also promotes changes at the transcriptional level, increasing the expression of genes related to glycolysis and fermentation in detriment of non-modulation of gene expression related to mitochondrial energy metabolism. Thus, in this study we investigated the effect of heme on the glucose metabolism of T. cruzi epimastigote using biochemical and metabolomic approaches. Our results showed that inhibition of the glycolysis, mediated by 2-deoxyglucose, impaired more than 50% of proliferation of epimastigotes maintained with heme, abolishing the increase in proliferation induced by the porphyrin. When we evaluate the glucose concentration in the culture medium, we observed that glucose was consumed by the parasites during the culture and depleted of the medium on the 7th day, causing a retention in parasite proliferation cultivated with heme. On the other hand, the rise in this hexose supply increased the proliferation induced by porphyrin on the 10th day of culture, which glucose was still available in the culture medium in this case. Interestingly, we showed that the porphyrin was capable of stimulate the increase in glucose uptake by the parasites over the days of culture, being this uptake dependent on glucose supply. Concomitantly, was observed the reduction of supernatant pH after days in culture. When assessing mitochondrial physiology, we showed that parasites cultured with heme for seven days have similar O2 consumption compared to control parasites, but with an increase in the maximum capacity of the electron transport system (STE) in the absence of exogenous substrates. However, the addition of glucose triggered an immediate reduction in the mitochondrial O2 consumption, in the ETS, and in the spare respiratory capacity in these heme-cultured parasites This repression of respiratory metabolism by glucose indicates a transition to a fermentative metabolism (Crabtree effect). Corroborating these data, we observed through metabolomics that the intracellular level of phosphoenolpyruvate (PEP) was increased, but not the pyruvate, indicating that PEP can be directed to the aerobic fermentation in glycosome. Although no change was observed in the succinate levels, the final product of succinic fermentation, the transcriptomic analysis allowed us to understand that this pathway intermediates can fuel other reactions in parasite. We also observed an increase in the amino acids uptake involved with the antioxidant system and NAD+ regeneration, which was increased in the parasite. Our results together with previously published transcriptomic analysis suggest that heme induced metabolic adaptations in epimastigote forms for an energy metabolism based on glycolysis and fermentation allowing its proliferation and survival.