Molecular and functional characterization of a tandem-repeat galectin from the freshwater snail Biomphalaria glabrata, intermediate host of the human blood fluke Schistosoma mansoni

Abstract

In the present study, a tandem-repeat type galectin was characterized from an embryonic cell line (Bge) and circulating hemocytes of the snail Biomphalaria glabrata, intermediate host of the human blood fluke Schistosoma mansoni. The predicted B. glabrata galectin (BgGal) protein of 32 kDa possessed 2 carbohydrate recognition domains, each displaying 6 of 8 conserved amino acids involved in galactoside-binding activity. A recombinant BgGal (rBgGal) demonstrated hemagglutinating activity against rabbit erythrocytes, which was specifically inhibited by galactosecontaining sugars (lacNAc/lac > galNAc/gal). Although native galectin was immunolocalized in the cytoplasm of Bge cells and the plasma membrane of a subset of snail hemocytes (60%), it was not detected in cell-free plasma by Western blot analysis. The findings that rBgGal selectively recognizes the schistosome-related sugar, lacNAc, and strongly binds to hemocytes and the tegument of S. mansoni sporocysts in a sugar-inhibitable fashion suggest that hemocyte-bound galectin may be serving as pattern recognition receptor for this, or other pathogens possessing appropriate sugar ligands. Based on molecular and functional features, BgGal represents an authentic galectin, the first to be fully characterized in the medically-important molluscan Class Gastropoda.

Control of infection of Biomphalaria alexandrina (Ehrenberg, 1831) with Schistosoma mansoni Sambon, 1907 using Eucalyptus camaldulensis

“…Haemocytes of Biomphalaria quickly recognise parasites and produce ROS to kill the invading pathogens. This is an important component of Biomphalaria cellular defences; it determines the susceptibility or resistance to schistosome infection and production of cercariae (bendeR et al 2007, yoSHino et al 2008, ittiPRaSeRt et al 2010, Moné et al 2011. Interference with the snail immune system through improving the antioxidant system may help the snails to overcome the infection-associated stress and finally lead to retarding parasite development.…”

Hemocytes and Plasma of the Eastern Oyster (Crassostrea virginica) Display a Diverse Repertoire of Sulfated and Blood Group A-modified N-Glycans*

“…(59). Although similarities in the glycosylation of both the schistosome and snail are known (60,61), the actual ligands of the snail galectin remain unknown.…”

“…Although similarities in the glycosylation of both the schistosome and snail are known (60,61), the actual ligands of the snail galectin remain unknown. As a parallel with the oyster-Perkinsus interaction (54), it was proposed that the snail galectin may participate in host-Schistosoma interactions, yet to be determined (59). However, N-glycans are not the only parasite ligands for host galectins, as shown by the binding of T. vaginalis lipoglycan to human galectin-1 on epithelia (62).…”

cDNA cloning and mRNA expression of a tandem-repeat galectin (PoGal2) from the pearl oyster, Pinctada fucata

“…Sequence analysis indicated that PoGal2 consisted of two canonical galectin CRDs connected by linkers with 62 amino acid residues, which were longer than those of Manila clam (Kim et al, 2008) and snail (Yoshino et al, 2008). So far, the galectins with two CRDs were only isolated from Manila clam (Kim et al, 2008), abalone (ABN54798) and freshwater snail (Yoshino et al, 2008), which were typical tandem-repeat galectins (Leffler et al, 2004;Vasta et al, 2004).…”

“…A tandem-repeat galectin, McGal from Manila clam Ruditapes philippinarum, has also been proven to bind to the surface of Perkinsus olseni as PRR, and it is up-regulated after challenge with P. olseni or Vibrio tapetis (Kim et al, 2008). Another tandem-repeat galectin, BgGal from freshwater snail Biomphalaria glabrata, selectively recognizes the schistosome-related sugar lacNAc and strongly binds to hemocytes and the tegument of Schistosoma mansoni sporocysts in a sugar-inhibitable fashion (Yoshino et al, 2008). A multidomain galectin of eastern oyster Crassostrea virginica (CvGal) is responsible for recognizing the protozoan parasite Perkinsus marinus (Tasumi and Vasta, 2007).…”