A Role for Insect Galectins in Parasite Survival

Department of Molecular & Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, United States
Cell (Impact Factor: 32.24). 11/2004; 119(3):329-41. DOI: 10.1016/j.cell.2004.10.009
Source: PubMed


Insect galectins are associated with embryonic development or immunity against pathogens. Here, we show that they can be exploited by parasites for survival in their insect hosts. PpGalec, a tandem repeat galectin expressed in the midgut of the sandfly Phlebotomus papatasi, is used by Leishmania major as a receptor for mediating specific binding to the insect midgut, an event crucial for parasite survival, and accounts for species-specific vector competence for the most widely distributed form of cutaneous leishmaniasis in the Old World. In addition, these studies demonstrate the feasibility of using midgut receptors for parasite ligands as target antigens for transmission-blocking vaccines.

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    • "Drosophila and sand fly galectins regulate development and de - fense against bacterial and parasitic pathogens ( Pace and Baum , 2004 ; Kamhawi et al. , 2004 "
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    • "The multivalency of galectins resulting from their oligomerization is not only key to their cooperative binding to complex carbohydrate ligands and their ability to crosslink surface glycans and form lattices (Vasta et al., 2004; Rabinovich et al., 2007), but would also enable galectins to facilitate the attachment of pathogens to the cell surface (Ahmad et al., 2004; Nieminen et al., 2007; Vasta, 2009). This subversion of galectins functions as PRRs has already been reported for the galectin-mediated attachment of viruses (Ouellet et al., 2005; Garner et al., 2010; St-Pierre et al., 2011; Yang et al., 2011), bacteria (Okumura et al., 2008), and eukaryotic parasites (Kamhawi et al., 2004). Prior studies have provided evidence that the release of sialic acid by the activity of the IAV neuraminidase promotes the adhesion of S. pneumoniae to airway epithelial cells in the form of a biofilm, that makes the pathogen less accessible to host factors and antibiotics and facilitates host invasion (Trappetti et al., 2009). "
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    • "Intriguingly, galectin-mediated bridging of L. major to host cells is also important at another point in the parasite life cycle. Valenzuela and co-workers found that a galectin homolog in the midgut of the sand fly Phlebotomus papatasi participates in binding of L. major at the procyclic phase to gut epithelial cells during infection of this obligate insect host (35). The L. major parasite replicates in the sandfly midgut and differentiates into the metacyclic phase that is highly infectious to mammalian hosts and is transmitted during insect bites. "
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