Subproject 4

SPINK1 and antibody formation

 

The main issue of this project is to investigate the protein SPINK1 (Serin Protease Inhibitor Kazal-Type 1) and its interaction with antibodies. The physiological function of SPINK1 is to inhibit the digestion enzyme trypsin within the pancreas, where trypsin is stored as an inactive premature enzyme. Otherwise the pancreas would be subject to damage by the digestive effect of trypsin and subsequent development of pancreatitis. Thus, defects of SPINK1, for example triggered by SPINK1 mutations, are associated with chronic pancreatitis (CP). Defect and misfolded SPINK1 accumulated in the endoplasmic reticulum (ER) tends to result in pancreatic diseases. Up to 25 % of CP patients show N34S SPINK1 mutation. Yet, this mutation occurs also in 2.5 % of the healthy population. Additionally, both wild type and mutant SPINK1 behave similarly concerning for instance trypsin binding and inhibitory effects. Thus, the presence of N34S SPINK1 mutation alone cannot be the cause of CP. Rather it is a risk indicator for developing CP. There must be a second trigger involved. In addition, autoantibodies against SPINK1 were found in up to 43 % of CP patients. The relationship between these factors is to be investigated in this project. For this purpose, one step is to study the structure and conformation of both the wild type SPINK1 and the N34S SPINK1 mutation. Found conformational changes in the beta sheet structure are examined in the next step concerning their relevance to antibody binding. Therefore, the binding affinity between the autoantibodies and SPINK1 is determined under various experimental conditions. This is done using single-molecule force microscopy, with which the differences between wild type and mutant can be clearly identified. This results in the possibility to develop a test to detect and quantify with much higher sensitivity than previously possible SPINK1 autoantibodies. Thus a widespread problem of clinical autoantibody tests for studies in humans could be solved and this would allow to optimize an assay for the detection of SPINK1 autoantibodies.

 

 

Supervisor

Prof. Dr. rer. nat. Mihaela Delcea

 

Team

Annelie Klein

 

Former employees

Felix Nagel

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