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Home arrow Economics arrow American Trypanosomiasis Chagas Disease, Second Edition: One Hundred Years of Research


The secretory pathway

The secretory pathway in T. cruzi involves the endoplasmic reticulum (ER), the Golgi complex, and a system of vesicles that bud from the Golgi cisternae and migrate toward the flagellar pocket, where they fuse and discharge their contents into the flagellar pocket. ER cisternae are seen around the nucleus, and these radiate toward all regions of the cell, especially the peripheral microtubule-containing region. Both rough and smooth ER cisternae are present. The Golgi complex is always located close to the flagellar pocket and is essentially similar to that found in other cells. Rab7, a small GTPase involved in membrane trafficking, was also detected in the Golgi complex of trypanosomes.46 These vesicles present a rich collection of proteins involved in metabolism, signaling, nucleic acid binding, and parasite survival and virulence.47 The vesicles released by T. cruzi also contain a homogeneous population of tRNA- and rRNA-derived small RNAs. Extracellular vesicle cargo could be delivered to other parasites and to susceptible mammalian cells, promoting metacyclogenesis and conferring susceptibility to infection, respec- tively.48 Fernandez-Calero49 compared the small RNA cargo of extracellular vesicles from T. cruzi epimastigotes with the respective intracellular compartment using deep sequencing. Compared with the intracellular compartment, the shed extracellular vesicles showed a specific extracellular signature that included distinctive patterns of small RNAs derived from rRNA, tRNA, sno/snRNAs, and protein coding sequences, which evidenced specific secretory small RNA processing pathways. The shed extracellular vesicles are also enriched with glycoproteins of the gp85/ trans-sialidase superfamily and other a-galactosyl-containing glycoconjugates, such as mucins. Depending on the origin (strain) of the extracellular microvesicles, different immune responses are triggered.50 These shedding vesicles can also increase the inflammatory response in cardiac tissues.6

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