Dramatic reorganisation of Trichomonas endomembranes during amoebal transformation: A possible role for G-proteins

University of Cambridge, Cambridge, England, United Kingdom
Molecular and Biochemical Parasitology (Impact Factor: 1.79). 08/2006; 148(1):99-102. DOI: 10.1016/j.molbiopara.2006.02.022
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Available from: Mark Field
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    • "The free-swimming ovoid cells, which resemble the familiar image of a flagellated protozoan, transform into an amoeboid form (Fig. 1) upon contact with the urogenital tract. This process commences more or less immediately upon contact with host tissue and the transformation of a cell takes only minutes to complete (Lal et al., 2006). The parasite's morphogenesis entails at least two distinct but simultaneous processes: (i) the dramatic shape transition and (ii) the adherence to host cells. "
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    ABSTRACT: The human pathogen Trichomonas vaginalis has the largest protozoan genome known, potentially encoding approximately 60,000 proteins. To what degree these genes are expressed is not well known and only a few key transcription factors and promoter domains have been identified. To shed light on the expression capacity of the parasite and transcriptional regulation during phase transitions, we deep sequenced the transcriptomes of the protozoan during two environmental stimuli of the early infection process: exposure to oxygen and contact with vaginal epithelial cells. Eleven 3' fragment libraries from different time points after exposure to oxygen only and in combination with human tissue were sequenced, generating more than 150 million reads which mapped onto 33,157 protein coding genes in total and a core set of more than 20,000 genes represented within all libraries. The data uncover gene family expression regulation in this parasite and give evidence for a concentrated response to the individual stimuli. Oxygen stress primarily reveals the parasite's strategies to deal with oxygen radicals. The exposure of oxygen-adapted parasites to human epithelial cells primarily induces cytoskeletal rearrangement and proliferation, reflecting the rapid morphological transition from spindle shaped flagellates to tissue-feeding and actively dividing amoeboids.
    Full-text · Article · May 2013 · International journal for parasitology
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    • "As an essential component of T. vaginalis urogenital tract colonization, minutes after contact with human urogenital tract cells, T. vaginalis undergoes a radical change in cell morphology (Lal et al., 2006). The free-swimming flagellate cell flattens and spreads out over the host cell tissue to become an amoeba. "
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    ABSTRACT: Trichomonas vaginalis is the most widespread non-viral pathogen of the human urogenital tract, infecting ∼3% of the world's population annually. At the onset of infection the protist changes morphology within minutes: the flagellated free-swimming cell converts into the amoeboid-adherent stage. The molecular machinery of this process is not well studied, but is thought to involve actin reorganization. We have characterized amoeboid transition, focusing in particular on TvFIM1, the only expressed protein of the fimbrin family in Trichomonas. Addition of TvFIM1 to actin polymerization assays increases the speed of actin filament assembly and results in bundling of F-actin in a parallel and anti-parallel manner. Upon contact with vaginal epithelial cells, the otherwise diffuse localization of actin and TvFIM1 changes dramatically. In the amoeboid TvFIM1 associates with fibrous actin bundles and concentrates at protrusive structures opposing the trailing ends of the gliding amoeboid form and rapidly redistributes together with actin to form distinct clusters. Live cell imaging demonstrates that Trichomonas amoeboid stages do not just adhere to host tissue, rather they actively migrate across human epithelial cells. They do so in a concerted manner, with an average speed of 20 μm/min and often using their flagella and apical tip as the leading edge.
    Full-text · Article · Mar 2013 · Cellular Microbiology
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    • "Important selected effectors identified in the T. vaginalis genome are indicated: small GTPases Rab, Rho and ARF, ESCRT proteins of the multi-vesicular bodies (MVB) and the G-proteins Gα. The Gα402 (TVAG_452120) protein is likely to localise to MVB-like structures (Lal et al. 2006). "
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    ABSTRACT: The draft genome of the common sexually transmitted pathogen Trichomonas vaginalis encodes one of the largest known proteome with 60,000 candidate proteins. This provides parasitologists and molecular cell biologists alike with exciting, yet challenging, opportunities to unravel the molecular features of the parasite's cellular systems and potentially the molecular basis of its pathobiology. Here, recent investigations addressing selected aspects of the parasite's molecular cell biology are discussed, including surface and secreted virulent factors, membrane trafficking, cell signalling, the degradome, and the potential role of RNA interference in the regulation of gene expression.
    Full-text · Article · Jan 2011 · Advances in Parasitology
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