Role of cathepsin B in intracellular trypsinogen activation and the onset of acute pancreatitis
Walter Halangk, … , Christoph Peters, Jan Deussing
Walter Halangk, … , Christoph Peters, Jan Deussing
Published September 15, 2000
Citation Information: J Clin Invest. 2000;106(6):773-781. https://doi.org/10.1172/JCI9411.
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Article

Role of cathepsin B in intracellular trypsinogen activation and the onset of acute pancreatitis

Abstract

Autodigestion of the pancreas by its own prematurely activated digestive proteases is thought to be an important event in the onset of acute pancreatitis. The mechanism responsible for the intrapancreatic activation of digestive zymogens is unknown, but a recent hypothesis predicts that a redistribution of lysosomal cathepsin B (CTSB) into a zymogen-containing subcellular compartment triggers this event. To test this hypothesis, we used CTSB-deficient mice in which the ctsb gene had been deleted by targeted disruption. After induction of experimental secretagogue–induced pancreatitis, the trypsin activity in the pancreas of ctsb–/– animals was more than 80% lower than in ctsb+/+ animals. Pancreatic damage as indicated by serum activities of amylase and lipase, or by the extent of acinar tissue necrosis, was 50% lower in ctsb–/– animals. These experiments provide the first conclusive evidence to our knowledge that cathepsin B plays a role in intrapancreatic trypsinogen activation and the onset of acute pancreatitis.

Authors

Walter Halangk, Markus M. Lerch, Barbara Brandt-Nedelev, Wera Roth, Manuel Ruthenbuerger, Thomas Reinheckel, Wolfram Domschke, Hans Lippert, Christoph Peters, Jan Deussing

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Figure 1

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Targeted disruption of the ctsb gene. (a) Strategy for inactivation of t...
Targeted disruption of the ctsb gene. (a) Strategy for inactivation of the ctsb-gene by homologous recombination in embryonic stem cells. (Top) Genomic structure and partial restriction map of the wild-type ctsb-locus (15, 47, 48). Exons are numbered and indicated by black boxes. External probes A and B used for Southern blot analyses are represented by black bars. (Middle) Targeting construct pMCB-11/1neo with 7.7 kb homology to the ctsb gene locus. A neomycin-resistance cassette was inserted into a BglII site in exon 4. The arrow marks the direction of transcription of the neomycin gene. (Bottom) Predicted ctsb-locus after homologous recombination. Broken line: plasmid vector pBluescriptII SK (+). B, BamHI; Bg, BglII; E, EcoRV; Eg, EagI; H, HindIII; K, KpnI. (b) Southern blot analysis of targeted ES cell clones. The 3′-external probe B was hybridized to BglII digested genomic DNA from wild-type E-14-1 ES cells and ES cell clones ECB-28 and ECB-31 with a targeted ctsb allele as indicated by the presence of an additional 6.8-kb DNA fragment. The 5′-external probe A was hybridized to KpnI and EagI digested DNA from the same ES cell clones, confirming homologous recombination in clones ECB-28 and ECB-31. (c) Southern blot analysis of tail DNA from offspring of an intercross of ctsb heterozygotes. Genotypes of progeny are indicated. (d) Northern blot analysis of ctsb mRNA expression. Total RNA was hybridized to a partial ctsb cDNA and a murine glyceraldehyde-3-phosphate dehydrogenase probe (G3PD). (e) Western blot analysis of CTSB protein expression from kidney lysosomal extracts; CTSB-m: mature CTSB (single chain form); CTSB-l: large subunit (two chain form). (f) CTSB enzyme activity in liver lysosomal fractions expressed as mU/mg protein (± SD; n = 3).