Functional characterization of common genetic risk variants in chronic pancreatitis.

• Applicant: Dr. Sebastian Beer
• Subject Area: Gastroenterology
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 322482394

Chronic pancreatitis (CP) is a progressive inflammatory disease of the pancreas, which usually provokes abdominal pain and can progress to exocrine and endocrine insufficiency by fibrotic remodeling of functional tissue. Major risk factors for CP are alcohol consumption and smoking, whereas the underlying pathomechanisms are not fully understood. In some cases mutations in cationic trypsinogen (PRSS1) are assumed being solely causative for the development of hereditary chronic pancreatitis. However, in much more patients several other genetic risk factors in PRSS1, CTRC, SPINK1, CPA1 or CFTR have been shown to be associated with chronic pancreatitis, although most of them are found in low frequencies. Functional analyses of variants in those genes point either to disturbances in the protease antiprotease balance or to endoplasmatic reticulum stress exhibiting the pancreatitis risk. Recently, the first genome wide association study for chronic pancreatitis identified one variant in the PRSS1-locus (rs10273639) and two variants in the CLDN2-MORC4-locus (rs12688220 and rs7057398) as a genetic risk for chronic pancreatitis. Those three together with a synonymous variant in CTRC (rs497078, c.180C>T) are common variants. Functional, disease related consequences are not conclusively elucidated in detail yet. Moreover it remains unclear if the named variants or one of the genetically linked variants are causative.This study aims to investigate the functional effects of common variants associated with chronic pancreatitis as well as selected candidates in linkage disequilibrium (LD). Moreover interaction with environmental risk factors will be assessed. Candidates in LD are chosen by the use of phylogenetic module complexity analysis. All variants are located either in promoter regions, within introns or are synonymous exonic variants. Therefore, their effect might be exhibited through changes in promoter activity, mRNA stability or alterations of splicing in a qualitative or quantitative manner. In a first step allele dependent expression of genes harboring or related to the variants will be investigated using human pancreatic tissue samples. Effects of variants on promoter activity and splicing will be analyzed using luciferase and splicing assays in different stable and primary cell lines. Involved nuclear proteins will be identified by electrophoretic mobility shift assays and DNA pull down assays. Additional experiments will be performed in the presence of ethanol and its metabolites as well as smoke extract. With this approach we will reveal insights into the pathomechanisms of CP, which is essential for improvement of prevention, diagnosis and therapy.

• DFG Programme: Research Grants