Intragenic duplication: a novel mutational mechanism in hereditary pancreatitis.
| Autor: | Joergensen MT; Department of Medical Gastroenterology, Odense University Hospital, University of Southern Denmark, Odense, Denmark. maiken.t.joergensen@ouh.regionsyddanmark.dk, Geisz A, Brusgaard K, Schaffalitzky de Muckadell OB, Hegyi P, Gerdes AM, Sahin-Tóth M |
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| Jazyk: | angličtina |
| Zdroj: | Pancreas [Pancreas] 2011 May; Vol. 40 (4), pp. 540-6. |
| DOI: | 10.1097/MPA.0b013e3182152fdf |
| Abstrakt: | 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. |
| Databáze: | MEDLINE |
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