Journal
PANCREAS
Volume 40, Issue 4, Pages 540-546Publisher
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1097/MPA.0b013e3182152fdf
Keywords
hereditary pancreatitis; human cationic trypsinogen; PRSS1; intragenic duplication; autoactivation; cathepsin B; enteropeptidase
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Funding
- Danish Cancer Society
- Dagmar Marshalls Foundation
- Fru Astrid Thaysens Legat
- Legat for Laegevidenskabelig grundforskning
- Ingemann O. Buch's Foundation
- Laegernes Forsikringsforening af
- National Institutes of Health [DK058088]
- Rosztoczy Foundation
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Objectives: In a hereditary pancreatitis family from Denmark, we identified a novel intragenic duplication of 9 nucleotides in exon-2 of the human cationic trypsinogen (PRSS1) gene (c.63_71dup) which at the amino-acid level resulted in the insertion of 3 amino acids within the activation peptide of cationic trypsinogen (p.K23_I24insIDK). The aim of the present study was to characterize the effect of this unique genetic alteration on the function of human cationic trypsinogen. Methods: Wild-type and mutant cationic trypsinogens were produced recombinantly and purified to homogeneity. Trypsinogen activation was followed by enzymatic assays and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Trypsinogen secretion was measured from transfected HEK 293T cells. Results: Recombinant cationic trypsinogen carrying the p.K23_I24insIDK mutation exhibited greater than 10-fold increased autoactivation. Activation by human cathepsin B also was accelerated by 10-fold. Secretion of the p.K23_I24insIDK mutant from transfected cells was diminished, consistent with intracellular autoactivation. Conclusions: This is the first report of an intragenic duplication within the PRSS1 gene causing hereditary pancreatitis. The accelerated activation of p.K23_I24insIDK by cathepsin B is a unique biochemical property not found in any other pancreatitis-associated trypsinogen mutant. In contrast, the robust autoactivation of the novel mutant confirms the notion that increased autoactivation is a disease-relevant mechanism in hereditary pancreatitis.
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