Biology subjects

Damasceno, F. S.

Publications and source records attributed to Damasceno, F. S..

5 recordsLinked to original sources

bioRxiv2025

Extracellular glutamine is essential in cell division and flagellar function in bloodstream forms of Trypanosoma brucei

Trypanosoma brucei is the etiologic agent of African trypanosomiasis, also known as sleeping sickness. In the mammalian host, T. brucei is present as replicative and non-replicative bloodstream forms (BSF) referred to as long slender and stumpy, respectively. In the insect vector, the developmental forms are procyclic (PCF), epimastigote, and metacyclic trypomastigote. It is well established that BSF use glucose as the main energy source, and PCF can use glucose but, in its absence, uses amino acids, mainly proline. Due to these facts, the metabolism of amino acids has been well studied in PCF, but less attention has been given to it in BSF. In the present work, we unveil the participation of glutamine (Gln), the most abundant amino acid in the human blood, in BSF proliferation. According to the data presented herein, in the absence of extracellular Gln, cell cycle progress, as well as kinetoplast and flagella distribution and function among daughter cells, are widely compromised, yielding polyploid multiflagellated cells with reduced motility. In addition, the Gln-poor medium resulted in cells with a massive alteration in the proteome glutamylation. These alterations were reverted when Gln was added to the culture media. An analysis of the glutamylproteome of cells incubated in Gln-poor medium, followed by a Gene Ontology (GO) analysis, suggested a relationship between glutamylation and biological processes such as gene expression and regulation, cell cycle, and bioenergetics metabolism, in addition to cytoskeleton dynamics in BSF of T. brucei.

cell biology↗

bioRxiv2024

Branched chain amino acids modulate the proteomic profile of Pro-induced differentiation for the infective stages of Trypanosoma cruzi

Trypanosoma cruzi, the causative agent of Chagas disease, undergoes a complex life cycle involving triatomine insects as vectors and mammals. The differentiation of epimastigote forms into metacyclic trypomastigotes within the insect vector is crucial for the parasites life cycle progression. Factors influencing this process, including temperature, pH, and nutritional stress, along with specific metabolite availability, play a pivotal role. Amino acids like Pro, His, and Gln support cell differentiation, while branched-chain amino acids (BCAAs) inhibit it. Interestingly, combining the pro-metacyclogenic amino acid Pro with one of the anti-metacyclogenic BCAAs results in viable metacyclics with significantly reduced infectivity. To explore the characteristics of metacyclic parasites differentiated in the presence of BCAAs, proteomics analyses were conducted. Metacyclics obtained in triatomine artificial urine (TAU) supplemented with Pro alone and in combination with Leu, Ile, or Val were compared. The analyses revealed differential regulation of 40 proteins in TAU-Pro-Leu, 131 in TAU-Pro-Ile, and 179 in TAU-Pro-Val, as compared to metacyclics from TAU-Pro. Among these, 22%, 11%, and 13% of the proteins were associated with metabolic processes, respectively. Notably, enzymes related to glycolysis and the tricarboxylic acid (TCA) cycle were reduced in metacyclics with Pro-BCAAs, while enzymes involved in amino acid and purine metabolic pathways were increased. Furthermore, metacyclics with Pro-Ile and Pro-Val exhibited elevated enzymes linked to lipid and redox metabolism. These findings suggest that the presence of BCAAs can reshape the metabolism of metacyclics, contributing to the observed reduction in infectivity in these parasites.

biochemistry↗

bioRxiv2023

How much (ATP) does it cost to build a trypanosome? A theoretical study on the quantity of ATP needed to maintain and duplicate a bloodstream-form Trypanosoma brucei cell

ATP hydrolysis is required for the synthesis, transport and polymerization of monomers for macromolecules as well as for the assembly of the latter into cellular structures. Other cellular processes not directly related to synthesis of biomass, such as maintenance of membrane potential and cellular shape, also require ATP. The unicellular flagellated parasite Trypanosoma brucei has a complex digenetic life cycle. The primary energy source for this parasite in its bloodstream form (BSF) is glucose, which is abundant in the hosts bloodstream. Here, we made a detailed estimation of the energy budget during the BSF cell cycle. As glycolysis is the source of most produced ATP, we calculated that a single parasite produces 6x1011 molecules of ATP/cell cycle. Biomass production accounts for [~]62% of the total energy budget, with translation being the most expensive process. Flagellar motility, variant surface glycoprotein recycling, transport and maintenance of transmembrane potential account for less than 30% of the consumed ATP. Finally, there is still [~]9% available in the budget that is being used for other cellular processes of unknown cost. These data put a new perspective on the assumptions about the relative energetic weight of the processes a BSF trypanosome undergoes during its cell cycle. Abstract ImportanceCells use ATP as the main energy currency for the synthesis, organization and maintenance of their macromolecules and cellular structures, in order to stay alive and proliferate. For this purpose, ATP is produced from external nutrients, and is spent by cells in the many processes that are necessary for maintenance and building up new cells. Despite its relevance and the impressive quantity of biological data available, very little is known about how much ATP is required for maintaining and duplicating a cell. In this paper, we present a calculation on how much of the ATP produced by catabolism of the nutrient glucose is used to energize the different processes known to occur during the cell cycle of the infective form of the trypanosomatid parasite that causes human sleeping sickness, the bloodstream form of Trypanosoma brucei.

biochemistry↗

bioRxiv2021

Fatty acid oxidation participates of the survival to starvation, cell cycle progression and differentiation in the insect stages of Trypanosoma cruzi

During its complex life cycle, Trypanosoma cruzi colonizes different niches in its insect and mammalian hosts. This characteristic determined the types of parasites that adapted to face challenging environmental cues. The primary environmental challenge, particularly in the insect stages, is poor nutrient availability. These T. cruzi stages could be exposed to fatty acids originating from the degradation of the perimicrovillar membrane. In this study, we revisit the metabolic fate of fatty acid breakdown in T. cruzi. Herein, we show that during parasite proliferation, the glucose concentration in the medium can regulate the fatty acid metabolism. At the stationary phase, the parasites fully oxidize fatty acids. [U-14C]-palmitate can be taken up from the medium, leading to CO2 production via beta-oxidation. Lastly, we also show that fatty acids are degraded through beta-oxidation. Additionally, through beta-oxidation, electrons are fed directly to oxidative phosphorylation, and acetyl-CoA is supplied to the tricarboxylic acid cycle, which can be used to feed other anabolic pathways such as the de novo biosynthesis of fatty acids. Author SummaryTrypanosoma cruzi is a protist parasite with a life cycle involving two types of hosts, a vertebrate one (which includes humans, causing Chagas disease) and an invertebrate one (kissing bugs, which vectorize the infection among mammals). In both hosts, the parasite faces environmental challenges such as sudden changes in the metabolic composition of the medium in which they develop, severe starvation, osmotic stress and redox imbalance, among others. Because kissing bugs feed infrequently in nature, an intriguing aspect of T. cruzi biology (it exclusively inhabits the digestive tube of these insects) is how they subsist during long periods of starvation. In this work, we show that this parasite performs a metabolic switch from glucose consumption to lipid oxidation, and it is able to consume lipids and the lipid-derived fatty acids from both internal origins as well as externally supplied compounds. When fatty acid oxidation is chemically inhibited by etomoxir, a very well-known drug that inhibits the translocation of fatty acids into the mitochondria, the proliferative insect stage of the parasites has dramatically diminished survival under severe metabolic stress and its differentiation into its infective forms is impaired. Our findings place fatty acids in the centre of the scene regarding their extraordinary resistance to nutrient-depleted environments.

biochemistry↗

bioRxiv2019

The effect of memantine, an antagonist of the NMDA glutamate receptor, in in vitro and in vivo infections by Trypanosoma cruzi

Chagas disease, caused by Trypanosoma cruzi, is a neglected tropical disease that affects 5-6 million people in endemic areas of the Americas. Presently, chemotherapy relies on two compounds that were proposed as trypanocidal drugs four decades ago: nifurtimox and benznidazole. Both drugs are able to eliminate parasitemia and to avoid seroconversion in infected people when used in the acute phase; however, their use in the chronic phase (the time when the majority of cases are diagnosed) is limited due to their serious side effects. Memantine is a glutamate receptor antagonist in the central nervous system of mammals that has been used for the treatment of Alzheimers disease. Our group previously reported memantine as a trypanocidal drug that is able to induce apoptosis-like death in T. cruzi. In the present work, we further investigated the effects of memantine on the infection of RAW 264.7 macrophages in vivo (in BALB/c mice). Here, we showed that memantine is able to diminish NO and Ca2+ entry in both LPS-activated and non-activated cells. These results, together with the fact that memantine was also able to reduce the infection of macrophages, led us to propose that this drug is able to activate a pro-oxidant non-NO-dependent cell defense mechanism. Finally, infected mice that were treated with memantine had diminished parasitemia, cardiac parasitic load, and inflammatory infiltrates. In addition, the treated mice had an increased survival rate. Taken together, these results indicate memantine to be a candidate drug for the treatment of Chagas disease. Author summaryChagas disease affects approximately 5 million people and is caused by the protist parasite Trypanosoma cruzi. Until now, there are no vaccines to prevent the human infection, and the therapy relies on the use of two drugs discovered more than 50 years ago, nifurtimox and benznidazole. Both drugs are efficient during the acute phase of the disease, however their efficacy in the chronic phase, when most of patients are diagnosed is controversial. In addition, both drugs are toxic, causing severe side effects during the treatment. For these reasons, new drugs against T. cruzi are urgently needed. In this work, we report a series of experiments supporting the repositioning of memantine, a drug used for treating Alzheimers disease, to treat the T. cruzi infection in an experimental infection model. Our data show that infected mice treated with memantine have diminished their parasitemia, cardiac parasitic load and inflammatory infiltrates and more importantly, they have diminished their mortality. Taken together, these results prompt memantine as a promising drug for treating Chagas disease.

microbiology↗