Gender-specific expression of complex-type N-glycans in schistosomes.

Sex-specific gene expression by Schistosoma mansoni worms has been demonstrated at the transcriptome as well as the proteome levels. In view of the important role of glycans in the biology of schistosomes and the interaction with their human host, we have investigated the sex-specific protein glycosylation. Mass spectrometric profiling and structural characterization of PNGase F-released N-glycans revealed the following gender-specific glycosylation patterns: Complex-type N-glycans of females mainly carried Gal(beta1-4)GlcNAc (LacNAc) and Gal(beta1-4)[Fuc(alpha1-3)]GlcNAc (Lewis x) antennae structures, whereas GalNAc(beta1-4)GlcNAc- (LacdiNAc; LDN) and GalNAc(beta1-4)[Fuc(alpha1-3)]GlcNAc (LDN-F) were prevalent in N-glycans from males. LDN(-F) motifs were found to occur as repeats on the antennae of large N-glycans that contained up to seven LDN(-F) units. The female complex-type glycans were mostly di-antennary and tri-antennary, whereas male structures were predominantly of the mono-antennary and di-antennary type. Oligomannosidic N-glycans were expressed at similar levels in females and males. The localization of the sex-biased glycan motifs was studied by immunofluorescence microscopy using defined anti-glycan monoclonal antibodies (mAbs). The Lewis x element was strongly expressed in the gut of both males and females, but with respect to tegument localization, the females expressed this structure, while Lewis x seemed to be almost completely absent from the male tegument. The expression of LDN-F was predominantly detected in the parenchyma of both male and female worms as well as in the tegument of the male ventral cavity facing the female. LDN was detected in the tegument of male and female worms at similar levels. The sex-specific expression and differential localization of these antigenic glycan motifs in schistosomes may play a role in male-female interactions during conjugal biology and may lead to a differential immune reaction of the host to the two sexes.