Interactions of dendritic cell lectins with glycosylated antigens - possible mechanisms for modulation of immune responses
Malin Bäckström, Department of Medical Biochemistry

We are studying the effects of glycosylation on the generation of immune responses. Many protein antigens are glycosylated and have the ability to interact with lectins, carbohydrate-binding proteins, on cells of the immune system, such as dendritic cells. As our model antigen we are using MUC1, a highly O-glycosylated epithelial mucin glycoprotein, which is upregulated in many forms of cancer and also shows an altered glycosylation in cancer cells compared to the normal epithelium. We can produce MUC1 in Chinese hamster ovary cells with several types of O-glycan structures, both cancer-related and normal structures. We are now using these different forms of MUC1 to study how they interact with dendritic cells and possibly to identify lectins on dendritic cells that can be involved in binding MUC1 and that can influence the outcome in terms of immune responses. This project will involve the generation of differentially glycosylated proteins in mammalian cells, determination of O-glycan structures on the proteins by mass spectrometry as well as experiments with cultured cells to investigate effects on cells of the immune system.

References: 1. M. Bäckström, T. Link, R. Graham, F.J. Olson, H. Karlsson, T. Noll, J. Burchell, J. Taylor-Papadimitriou and G.C. Hansson: Recombinant MUC1 mucin with a breast cancer-like O-glycosylation produced in Chinese hamster ovary cells. Biochemical J (2003) 376:677-686

2. F.J. Olson, M. Bäckström, H. Karlsson, J. Burchell and G.C. Hansson: A MUC1 reporter protein produced in CHO K1 cells has sialylated core1 O-glycans and becomes more densely glycosylated if co-expressed with polypeptide-GalNAc-T4 transferase. Glycobiology (2004) published on-line