Developmental O-glycan profile analysis shows pentasaccharide mucin-type O-glycans are linked with pupation of Tribolium castaneum

Eukaryotic cells can decorate their proteins with carbohydrate structures or glycans, significantly affecting the properties and activities of these proteins. Despite the importance of protein glycosylation in numerous biological processes, our knowledge of this modification in insects is far from complete. While N-glycosylation is the most studied, the study of O-glycans in insects is still very fragmentary and these studies are limited to a specific developmental stage or a specific tissue. In this article, matrix-assisted laser desorption/ionization (MALDI)-Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) technology was used to analyze the O-glycan profile for the different developmental stages of egg, larva, pupa, and adult of the red flour beetle Tribolium castaneum, an important insect model and pest worldwide. The results on the O-glycan profile showed that the mucin-type glycans dominate the O-glycome of the red flour beetle. Interestingly, some of the more complex mucin-type O-glycans, such as a tetra- (O-GalNAcGalGlcAGalNAc) and pentasaccharide O-glycan (O-GalNAc(GalGlcA)GalNAcGlcA), were highly abundant during the pupa stage, the intermediate stage between larval and adult stage in holometabolous insects, demonstrating that insect metamorphosis is accompanied with a change in the insect O-glycan profile. Together with the N-glycan profile, the current data are a foundation to better understand the role of protein glycosylation in the development of insects