Glycosylation of immunoglobulins is suspected to play a key role in the regulation of the immune system. In this thesis, mass spectrometry-based glycoproteomics methods were used to characterize... Show moreGlycosylation of immunoglobulins is suspected to play a key role in the regulation of the immune system. In this thesis, mass spectrometry-based glycoproteomics methods were used to characterize the glycosylation of various immunoglobulins. In Chapter 2 we describe the development of a glycoproteomics method to analyze IgE glycosylation. In Chapter 3 we reported partial O-glycosylation of IgG3. In addition to structural glycosylation research, we also analyzed antibody glycosylation in population cohorts. In Chapter 4 and Chapter 5, IgG Fc glycopeptide analysis was performed on blood samples using LC-MS(/MS). In a cohort of 76 ANCA vasculitis patients, low galactosylation and sialylation of IgG was associated with a higher chance of future relapse. Furthermore, in the approximately 1800 participants of the Leiden Longevity study (LLS), low galactosylation and sialylation of IgG, together with high fucosylation, showed association with markers of inflammation. We hope that the novel data presented in this thesis may contribute to the elucidation of the role of antibody glycosylation in the immune system, of which the understanding is currently still very limited. Show less
The post-translational modification of proteins known as adenosine diphosphate ribosylation (ADPr) is involved in a wide variety of important biological processes and is also associated with... Show moreThe post-translational modification of proteins known as adenosine diphosphate ribosylation (ADPr) is involved in a wide variety of important biological processes and is also associated with carcinogenesis and the process of aging. Therefore, a better understanding of the biology of ADP-ribosylation is crucial for the development of novel therapeutics. To facilitate this research, the availability of well-defined fragments of mono- and poly-ADP-ribose is essential. This Thesis describes the development of new synthetic methodologies to achieve this and the successful synthesis of well-defined ADP-ribosylated biomolecules. Show less
Glycan modifications of proteins and lipids form an integral part of the cell’s outermost layer and an array of ligands, adding a high degree of complexity to the cellular phenotype. While... Show more Glycan modifications of proteins and lipids form an integral part of the cell’s outermost layer and an array of ligands, adding a high degree of complexity to the cellular phenotype. While this complexity is an analytical challenge, it also offers a wide range of opportunities for biomarkers and treatment targets. This thesis deals with the analysis of colorectal cancer (CRC)-associated glycomic changes. Current knowledge on CRC-associated glycan changes and their biological role have been reviewed in Chapter 1. In Chapters 2, 3, and 6, we developed novel, high-end methodologies for the glycomic analysis of tissues and cell lines to be able to expand our knowledge on cancer glycomics and to overcome some limitations of current techniques. By applying these new methods, this thesis also covers the characterization of changes in glycosylation in CRC tissues as well as cell lines, thereby contributing to the understanding of CRC biology while identifying cancer-specific signatures underlying CRC development. These signatures can be further explored as potential markers to improve patient care. Additionally, in Chapter 5, we extended our research to pancreatic duct adenocarcinoma and characterized the N-glycome of PDAC cells with different metastatic potential and of a normal pancreatic duct cell line. Show less
