Hydrogen peroxide induces caspase activation and programmed cell death in the amitochondrial Tritrichomonas foetus

Abstract

Tritrichomonas foetus is an amitochondrial parasite protist which lacks typical eukaryote organelles such as mitochondria and peroxisomes, but possesses the hydrogenosome, a double-membrane-bound organelle that produces ATP. The cell death of amitochondrial organisms is poorly studied. In the present work, the cytotoxic effects of hydrogen peroxide on T. foetus and its participation on cell death were analyzed. We took advantage of several microscopy techniques, including videomicroscopy, light microscopy immunocytochemistry for detection of caspase activation, and scanning and transmission electron microscopy. We report here that in T. foetus: (1) H(2)O(2) leads to loss of motility and induces cell death, (2) the dying cells exhibit some characteristics similar to those found during the death of other organisms, and (3) a caspase-like protein seems to be activated during the death process. Thus, we propose that, although T. foetus does not present mitochondria nor any known pathways of cell death, it is likely that it bears mechanisms of cell demise. T. foetus exhibits morphological and physiological alterations in response to H(2)O(2) treatment. The hydrogenosome, a unique organelle which is supposed to share a common ancestral origin with mitochondria and has an important role in oxidative responses in trichomonads, is a candidate for participating in this event.

Growth inhibition and ultrastructural alterations induced by Δ24(25)-sterol methyltransferase inhibitors in Candida spp. isolates, including non-albicans organisms

“…Candida yeasts produced unfertile buds that remained closely associated with the mother cell, and appeared with or without various nuclei. The nucleus may also have an altered shape and/or with abnormal chromatin condensation that might be associated with apoptosis cell death, as previously described after treatment of C. albicans with AMB [29]; and also after treatment of Tritrichomonas foetus with hydrogen peroxide [32]. The presence of many cells with more than one nucleus may also indicate that ergosterol biosynthesis inhibitors are interfering with cytokinesis.…”

Naturally Occurring Triggers that Induce Apoptosis-Like Programmed Cell Death in Plasmodium berghei Ookinetes

“…RNS and ROS have been identified as inducers of apoptosis in a variety of protozoans and their effect has been reported to be concentration dependent (see reviews [10]–[12]). For example, H 2 O 2 at low concentrations (500 µM) caused Tritrichomonas foetus to undergo apoptosis-like death whereas at concentration of 8 mM necrotic death was observed [50].…”

DNA analysis of cattle parasitic protozoan Tritrichomonas foetus after photodynamic therapy

“…degradation of cytoplasmatic components, hydrogenosome shape changes, plasmatic membrane projections (blebs), flagellar internalization, release of lysosomal enzyme, cell shape changes, cytoplasm vacuolization, photosensitizing (PS) externalization, and caspase activation [4,25,[28][29][30][31][32][33][34][35]. In the present study, T. foetus treated with PDT associated with photosensitizer tetrasulfonated aluminium phthalocyanine (AlPcS 4 ) showed "ladder-patterned" DNA fragments, in conventional electrophoresis assay and longer tails in Comet Assay.…”

“…It was previously reported that PDT induces cell and hydrogenosome shape changes [34] and lysosomal enzyme release [64] in T. foetus. These structural changes, together with the data reported here, indicate that PDT may have induced PCD by apoptosis, autophagy or paraptosis, which was considered an alternative form of PCD by [65].…”