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Proteinase 3 is an IL-32 binding protein.
Daniela Novick1, Menachem Rubinstein, Tania Azam
1Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel. daniela.novick@weizmann.ac.il
Summary
Proteinase 3 (PR3) binds to the proinflammatory cytokine Interleukin-32 alpha (IL-32alpha). PR3 cleavage of IL-32alpha enhances its activity, suggesting therapeutic targets for immune-regulated diseases.
Area of Science:
- Immunology
- Biochemistry
- Molecular Biology
Background:
- Interleukin-32 (IL-32) is a proinflammatory cytokine.
- IL-32 isoforms induce other cytokines like IL-1beta and TNF-alpha.
- Proteinase 3 (PR3) is a serine protease and autoantigen in Wegener's granulomatosis.
Purpose of the Study:
- To identify soluble receptors or binding proteins for IL-32alpha.
- To investigate the interaction between IL-32alpha and PR3.
- To determine the functional consequences of PR3 binding and cleavage of IL-32alpha.
Main Methods:
- Ligand affinity chromatography using immobilized IL-32alpha.
- Mass spectrometry and N-terminal microsequencing for protein identification.
- Surface plasmon resonance to quantify binding affinity.
- Enzymatic activity assays and cytokine induction experiments.
Main Results:
- Proteinase 3 (PR3) was identified as a specific binding protein for IL-32alpha.
- High affinity binding was observed between IL-32alpha and both urinary and neutrophil-derived PR3.
- PR3 binding to IL-32alpha was independent of PR3's enzymatic activity.
- Limited cleavage of IL-32alpha by PR3 enhanced its pro-inflammatory activity.
- PR3-cleaved IL-32alpha showed increased induction of chemokines like macrophage inflammatory protein-2 and IL-8.
Conclusions:
- PR3 is a specific binding protein for IL-32alpha.
- PR3-mediated cleavage of IL-32alpha potentiates its cytokine-inducing activity.
- Targeting PR3 activity or IL-32alpha-PR3 interaction may offer therapeutic strategies for IL-32-mediated inflammatory diseases.