Analysis of core 1-derived O-GalNAc modified glycoproteins in a conditional transgenic Cosmc knockout mouse in the pancreas.

• Applicant: Dr. Gerrit Wolters-Eisfeld
• Subject Area: Gastroenterology
• Term: from 2015 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 275533756

Alterations in O-GalNAc glycosylation with expression of the Tn antigen is a hallmark of cancer and pathological states. In this project, the influence of Cosmc-derived differential O-GalNAc glycosylation, as observed in pancreatic intraepithelial neoplasias (PanIN), intraductal papillary mucinous neoplasms (IPMN), pancreatic adenocarcinomas (PDAC) and chronic pancreatitis (CP), on the function of the endo- and exocrine pancreas will be examined.To make such investigation possible a conditional Cosmc-KO, and a conditionally overexpressing polypeptide-GalNAc-transferase 2 (GalNT2) mouse line was generated and mated with the pancreas-specific Cre mouse lines Ptf1a, Pdx1 and Sox9. The molecular knockout of Cosmc, with overexpression of GalNT2 is probably the molecular mechanism resulting in expression of the Tn antigen in precursor lesions of pancreatic cancer and pancreatic ductal adenocarcinoma.A fundamental objective of this project should be the identification of pancreatic O-GalNAc glycans and the influence of differential O-glycosylation on the exocrine pancreatic function in wild type and transgenic mice. The influence of the altered O-GalNAc glycosylation on protein expression, localization and activity, as well as on cell biological processes in acinar cells, and a possible influence on inflammation, carcinogenesis and the development of metabolic diseases, exocrine pancreatic dysfunction and lipid metabolism will be examined. Results from the mouse models will be compared with samples from human PanIN, IPMN, PDAC and CP patients. Tn antigen-bearing proteins from the pancreas of mice and patient samples will be enriched via Tn antigen-specific lectin chromatography and subsequently identified by mass spectrometry analysis. The potential influence of altered O-GalNAc glycosylation is to be tested by examining pancreatic dependent clinically relevant parameters in the Tn antigen mouse model. The identified Tn antigen-bearing proteins will be characterized by biochemical and cell biological means to describe molecular effects of altered O-GalNAc glycosylation.Because changes in the T-synthase activity cause changes in the O-GalNAc glycosylation at a superordinated level, PDAC cell lines and human tissues of PanIN, IPMN and PDAC and CP will be assayed for T-sythase activity. Thus a direct correlation between T-synthase activity and Tn antigen expression can be performed.This project will lead to the identification and an improved understanding of the physiological and pathophysiological functions of O-GalNAc glycosylated proteins in the pancreas.

• DFG Programme: Research Grants