Catalase expression impairs oxidative stress-mediated signalling inTrypanosoma cruzi

Abstract

SUMMARYTrypanosoma cruziis exposed to oxidative stresses during its life cycle, and amongst the strategies employed by this parasite to deal with these situations sits a peculiar trypanothione-dependent antioxidant system. Remarkably,T. cruzi’s antioxidant repertoire does not include catalase. In an attempt to shed light on what are the reasons by which this parasite lacks this enzyme, aT. cruzicell line stably expressing catalase showed an increased resistance to hydrogen peroxide (H2O2) when compared with wild-type cells. Interestingly, preconditioning carried out with low concentrations of H2O2led untransfected parasites to be as much resistant to this oxidant as cells expressing catalase, but did not induce the same level of increased resistance in the latter ones. Also, presence of catalase decreased trypanothione reductase and increased superoxide dismutase levels inT. cruzi, resulting in higher levels of residual H2O2after challenge with this oxidant. Although expression of catalase contributed to elevated proliferation rates ofT. cruziinRhodnius prolixus, it failed to induce a significant increase of parasite virulence in mice. Altogether, these results indicate that the absence of a gene encoding catalase inT. cruzihas played an important role in allowing this parasite to develop a shrill capacity to sense and overcome oxidative stress.