Mass spectrometry-based analysis of quantitative glycosylation patterns: glyco-proteomic tools in disease and therapy monitoring

Supervisor:Andreas Rizzi, Institute of Analytical Chemistry

Student: Claudia Michael

Protein glycosylation patterns as well as glyco-structures present in glycolipids (like gangliosides) have attracted major interest in the last decade. Protein glycosylation influences protein half life in organisms, their binding strengths to receptors, activators, inhibitors etc., decisively contributes to cell-cell recognition and adhesion and serves as a structural motif for immunological responses. These later aspects are decisive for glycolipids as well. Up to now, a number of congenital diseases are known as resulting from glycosylation related disorders in which either the appropriate glycan assembling is affected or its degradation. In addition, there is ample evidence that with certain acquired diseases the activity of special glycosyl-transferases is enhanced or reduced, particularly, with certain types of cancer where the activity of some fucosyl-transferases is enhanced and where the number of sialic acids in the glycans is changed. Analytical tools allowing a fast and reliable quantitative comparison between different cell states (control vs. stressed/ disease) are thus of high relevance for identifying and evaluating particular glycosylation patterns as potential early-onset biomarkers for diseases and/or therapeutic intervention control. Reliable quantitative data are needed for proofing hypotheses linking glycosylation patterns with diseases and corroborate these glycosylation patterns as potential biomarkers.

The proposed project involves in a first step the development/improvement of dervatization strategies allowing quantitative multistage mass spectrometry of glycans enzymatically cleaved off from proteins or lipids. In this first step a refined analytical methodology will be established and evaluated regarding reproducibility and sensitivity using standard glycoproteins. In subsequent steps the methodology will be applied to research topics associated with quantitative glycomics. A selection of these topics are: (i) Quantitative differences in the carbohydrate pattern of gangliosides isolated from cell membranes of healthy control and diseased persons. (Will be done in a cooperative project with the group of A.Zamfir, Universityof Arad). (ii) Quantitative differences in the glycosylation profiles in serum proteins as potential cancer markers. (Will be done in a cooperative project with the group of Ch.Gerner, Med.Univ. Wien). (iii) The influence of glycosylation of synapsins in the context of memory formation investigated with synapsins isolated from neuronal cells of mice hippocampus (Cooperation with Prof. G. Lubec, Med.Univ. Wien)

This subproject focusing on glycomics and glycoproteomics methodology will be linked to other subprojects within this IK focusing on protein modifications and protein interactions with bioactive compounds.