INVESTIGADORES
DE MIGUEL natalia
congresos y reuniones científicas
Título:
Proteomics approach to identify novel proteins on the surface of Trichomonas vaginalis involved in pathogenesis
Autor/es:
DE MIGUEL N; RIESTRA A; JOHNSON PJ
Reunión:
Congreso; IX Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2011
Institución organizadora:
Sociedad Argentina de Parasitologia
Resumen:
The unicellular parasitic Trichomonas vaginalis is the causative
agent of trichomoniasis, the most
prevalent non-viral sexually transmitted disease in humans. Because T. vaginalis is an obligate
extracellular pathogen, proteins on the surface may play a critical role
host-parasite interaction and the consequent pathogenesis. In this study, we
used cell surface biotinylation and multidimensional protein identification technology
(MudPIT) to identify the surface proteome of six strains of Trichomonas vaginalis with differing
adherence capacities to vaginal epithelial cells (1). A combined total of 411
proteins were identified, and of these, 11 were found to be more abundant in
adherent strains relative to less adherent parasites.
As proof of principle and to
investigate a possible role in pathogenesis, we report the identification and
functional characterization of two surface proteins detected in the proteome:
Tetraspanin-6 (TSP6) and Tetraspanin-1 (TSP1). These proteins are members of
the tetraspanin family, which comprises a large superfamily of cell
surface-associated membrane proteins that has been implicated in fundamental
biological processes, including cell adhesion, migration, fusion and
proliferation (2).
Our studies showed that TSP6 targets
to both the plasma membrane and the flagella of free living parasites (Fig 1).
The protein relocalizes during exposure to vaginal epithelial cells (VECs). The
complex localization and expression pattern of TSP6 suggests that its intracellular
trafficking and distribution must be tightly regulated during parasite
pathogenesis.
In order to evaluate TSP6 function,
cell adhesion and migration assays were performed using parasites that
over-express full length and C-terminal truncated version of TSP6. Although no
effect was observed on parasite that overexpress full length TSP6, when the C-terminal
tail is removed (TSP6DCt),
exogenous TSP6 exerted a dominant negative effect, as it significantly reduced
migration through matrigel invasion chambers compared with parasites
transfected with empty plasmid. In addition, TSP6DCt does not relocalize upon exposure
to VECs as observed for the full length protein. In conclusion, TSP6 appears to
influence cellular migration, with the TSP6 tail being of particular importance
in determining the outside-in signals that follow ligand engagement. The
elucidation of determinants involved in the process of migration may reveal
virulence factors and novel therapeutic targets to combat disease.
In
addition, a related protein, TSP1, has been shown to reside in exosomes as well
as large multivesicular bodies that accumulate upon contact of the parasite
with host cells. Exosomes are small membrane vesicles (50- to 100-nm) released
into the extracellular environment upon exocytic fusion of multivesicular bodies
with the cell surface. These vesicles are increasingly recognized as
significant vehicles for intercellular communication (3). Our results indicate that TSP1
is present in vesicles with morphological and biochemical characteristics of
exosomes. Interestingly, these vesicles appear to modulate
host-parasite communication.