Rapid glycosylation analysis of mouse serum glycoproteins separated by supported molecular matrix electrophoresis

Previously, we developed a novel separation technique, namely, supported molecular matrix electrophoresis (SMME), which separates mucins on a PVDF membrane that impregnated with a hydrophilic polymer (such as polyvinyl alcohol), so it has the characteristics that are compatible with glycan analysis of the separated bands. Here, we describe the first instance of the application of SMME to mouse sera fractionation and demonstrate their differences from the pooled human sera fractionation by SMME. Furthermore, we have developed a fixation method for the lectin blotting of SMME-separated glycoproteins by immersing the SMME membranes into acetone solvent followed by heating. It showed that the amount of protein samples required for SMME were reduced more than 4-fold than that of the process of SDS-PAGE. We applied these techniques for the detection of glycosylation patterns of serum proteins from Fut8^+/+ and Fut8^-/- mice, further analyzed N-linked and O-linked glycans from the separated γ-bands by mass spectrometry, and demonstrated that there are α2,8-sialylated O-glycans contained in mouse sera glycoproteins. SMME can provide simple, rapid sera fractionation, glycan profiling differences between the bands of two samples and a new insight into the underlying mechanism that responsible for related diseases. SIGNIFICANCE: We describe that the first application of SMME can separate mouse serum proteins into six bands and identify the major protein components of each fraction in mouse serum separated by SMME. Furthermore, we successfully developed a fixation method for lectin blotting of SMME-separated glycoproteins and applied to the detection of glycosylation patterns of serum glycoproteins from Fut8^+/+ and Fut8^-/- mice, also, the method is promising for detecting glycan profiling differences between two samples in both research and clinical settings.

Glycan Recognition and Application of P-Type Lectins

Cation-dependent mannose 6-phosphate receptor (CD-MPR) and cation-independent MPR (CI-MPR) belong to the P-type lectin family. Both intracellular and cell surface MPRs can recognize and bind with the terminal mannose 6-phospahte (M6P) residues of N-glycans attached to the mammalian lysosomal enzymes and the related co-factors. Domain9 (Dom9), which is one of the extracytoplasmic region of the CI-MPR, has relatively higher affinity for M6P residues. Here we describe the production of recombinant Dom9-His protein by Pichia pastris, purification, and application as a probe for lectin blotting.

The effect of pyometra on glycosylation of proteins in the uterine tissues from female dogs

The main aim of this study was to investigate the effect of pyometra on glycosylation of proteins in the uterine tissues from female dogs, using western blotting with selected lectins (Sambucus nigra agglutinin - SNA and Maackia amurensis agglutinin - MAL II). In addition protein pattern of examined tissues was also evaluated. The study was performed on 10 female dogs undergoing ovariohysterectomy because of pyometra and 10 clinically healthy female dogs, undergoing elective spaying (ovariohysterectomy). Uterine tissue samples of 1 cm² were taken from the middle region of each uterine horn in both group of animals immediately after ovariohysterectomy. Tissue samples were homogenized and analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting with SNA and MAL II. SDS-PAGE analysis showed differences between pyometra samples and controls in the amount of obtained protein fractions and the protein content in the individual fractions. Five protein (with a molecular weight of 193.78 kDa, 103.18 kDa, 77.67 kDa, 70.39 kDa, and 53.00 kDa) were found only in the pyometra samples. The remaining fractions differed in intensity of staining, which indicated differ abundance of a given protein. The results of western blotting with SNA and MAL II demonstrated that the pattern obtained from densitometric analysis differs between adequate healthy and pyometra samples with regard to the amount of protein fraction obtained as well as the intensity of staining of particular fraction. The pyometra tissues contained seven SNA-binding proteins (with a molecular weight 189.94 kDa, 165.51 kDa, 100.94 kDa, 59.42 KDa, 41.32 kDa, 35.16 kDa, and 32.6 kDa) that were not in the healthy tissues. Of the nine remaining fractions, six showed significantly higher (P < 0.05) intensity of staining in the healthy uterine tissues. In turn, the MAL II-binding protein with a molecular weight 75.85 kDa, 51.12 kDa, and 49.98 kDa were found only in the pyometra samples. Of the 28 remaining fractions, ten demonstrated significantly higher (P < 0.05), and five fractions had significantly lower (P < 0.05) intensity of staining in the pyometra tissues. The results obtained indicate that proteins in uterine tissues from female dogs with pyometra are differently glycosylated compared to normal uterine tissues. These findings provide the basis for further studies of the possible role of glycosylation in the pathogenesis of canine pyometra.