Biology subjects

Alcantara, C. d. L.

Publications and source records attributed to Alcantara, C. d. L..

3 recordsLinked to original sources

bioRxiv2024

Cytosol-living Trypanosoma cruzi amastigotes scavenge cholesterol from host ER and Golgi complex

Chagas Disease, caused by the protozoan parasite Trypanosoma cruzi, stands as a prevalent neglected disease in Latin America. The amastigote stage, the replicant intracellular form of the parasite, is a crucial player in infection persistence within vertebrate hosts. The amastigotes exhibit remarkable adaptability regarding the cell type that they infect, being able to modulate their metabolism and growth based on the host cell resources availability. Lipid metabolism emerges as a key determinant of amastigote growth, with a dependency on the host cells lipid resources. While the parasite can synthesize some sterols and fatty acids, it also scavenges these essential components, particularly cholesterol, from the host. Alterations in the hosts cholesterol metabolism, potentially regulated by SREBPs, contribute to increased intracellular cholesterol levels, fostering parasite development. However, the mechanisms underlying cholesterol uptake by amastigotes remained elusive. Here, we investigate the cholesterol trafficking mechanism from host cells to amastigotes by employing a fluorescent cholesterol analog. Using advanced imaging techniques, such as confocal fluorescence microscopy and high-resolution volume electron microscopy we demonstrated that amastigotes internalize extracellular-derived cholesterol, defined the uptake kinetics for cholesterol by amastigotes, and demonstrated that cholesterol is important for amastigote development. Analysis of the interaction of host cell ER with the amastigotes revealed by the presence of membrane contact sites between this organelle and the amastigote plasma membrane. We also showed that amastigotes can take up host ER and Golgi proteins, probably by endocytosis, paving a new mechanism for host cell scavenging of molecules by the parasite. Author SummaryChagas Disease, a widespread yet often overlooked challenge in Latin America, is driven by the parasite Trypanosoma cruzi. Understanding the amastigote stage, the parasites replicative form, is crucial for grasping infection persistence. This study reveals a critical survival strategy - amastigotes adeptly scavenging cholesterol from host cells. We demonstrated that the amastigotes can take up cholesterol from the host and that cholesterol is important for parasite development. Analysis of host cell organelles involved with cholesterol traffic, ER and Golgi, suggested their involvement, establishing crucial conduits for cholesterol acquisition. Deciphering these mechanisms illuminates the intricate interplay between parasite and host, presenting a potential treatment target. The parasites reliance on host cholesterol underscores adaptable growth strategies. This breakthrough deepens Chagas Disease understanding, paving the way for targeted therapeutic interventions.

cell biology↗

bioRxiv2023

Trypanosoma cruzi VDU deubiquitinase mediates surface protein trafficking and infectivity

Ubiquitylation is a post-translational modification promoting protein degradation. Within the endomembrane system ubiquitylation marks proteins for lysosomal processing. Deubiquitinases (DUBs) cleave ubiquitin from modified proteins and, in the case of surface proteins, prevent lysosomal targeting and thus play a major role in controlling turnover. In Trypanosoma cruzi, the etiological agent of Chagas disease, acquisition of nutrients in parasites proliferating within the blood meal of insect vectors occurs via the cytostome, a unique structure connected to a long tubular cytopharynx. Contents are delivered to late endosomes and accumulate in reservosomes, equivalent to lysosomes. When starved, T. cruzi differentiates into mammalian infective trypomastigotes, which are cell cycle arrested. Here we asked what roles ubiquitylation plays in this unique endocytic process by interrogation of the T. cruzi ortholog of VDU (von Hippel-Lindau-interacting deubiquitylating enzyme)/USP33 (ubiquitin-specific protease). We found that TcVDU expression level inversely correlated with transferrin endocytosis, and that overexpression led to a longer retention of the endocytic cargo near the cytostome. TcVDU itself was found enriched in the anterior region of the parasite, in proximity to endocytic cargo. Most importantly, TcVDU overexpression reduced parasite invasion capacity and led to increased release of trans-sialidase. These alterations in the abundance of multiple surface proteins in TcVDU mutants indicate a key role of TcVDU in modulating the T. cruzi surface by affecting the endosomal traffic and consequently the host-parasite interface. Author summaryTrypanosoma cruzi is the cause of Chagas disease that affects large populations of Central and South America. Disease is spreading to other continents due to poor control of blood transfusion from donors with chronic and undiagnosed infection, migration and drug treatment with limited performance and undesired side effects. Proliferating forms of T. cruzi acquire nutrients through the cytostome, a cell surface opening connected to a long tubular cytopharynx. Internalized material is endocytosed in the cytopharynx. This is distinct from other members of the Trypanosomatids, which endocytose material exclusively through the flagellar pocket. By using CRISPR gene editing and overexpression we demonstrated that a conserved deubiquitinase (VDU) is a key control element for traffic from the cytopharynx to endosomal compartments in T. cruzi. Changed levels of VDU modify endosomal traffic and largely impact the parasite surface, causing changes in infectivity.

microbiology↗

bioRxiv2020

Let it bud: an ultrastructural study of Cryptococcus neoformans surface during budding events

Cryptococcus neoformans is a fungal pathogen that causes life-threatening infections in immunocompromised individuals. It is surrounded by three concentric structures that separate the cell from the extracellular space: the plasma membrane, the cell wall and the polysaccharide capsule. Although several studies have revealed the chemical composition of these structures, little is known about their ultrastructural organization and remodeling during C. neoformans budding event. Here, by combining the state-of-the-art in light and electron microscopy techniques we describe the morphological remodeling that occurs synergistically among the capsule, cell wall and plasma membrane during budding in C. neoformans. Our results show that the cell wall deforms to generate a specialized budding region at one of the cells poles. This region subsequently begins to break into layers that are slightly separated from each other and with thick tips. We also observe a reduction in density of the capsular polysaccharide around these specialized regions. Daughter cells present a distinct spatial organization, with polysaccharide fibers aligned in the direction of budding. In addition, to control the continuous openings between mother and daughter cells, the latter developed a strategy to shield themselves by forming multilamellar membrane structures in conjunction with their capsules. Together, our findings provide compelling ultrastructural evidence for a dynamic C. neoformans surface remodeling during budding and may have important implications for future studies exploring these remodeled specialized regions as drug-targets against cryptococcosis.

microbiology↗