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Uncertainties in the classification of human cationic trypsinogen (PRSS1) variants as hereditary pancreatitis-associated mutations.

ABSTRACT: Autosomal dominant hereditary pancreatitis has been conclusively linked with cationic trypsinogen (PRSS1) mutations p.R122H and p.N29I, which can be found in approximately 90% of mutation-positive cases. To date, 35 additional rare or private PRSS1 variants have been identified in subjects with hereditary or sporadic, idiopathic chronic pancreatitis. Despite the lack of sufficient genetic and functional evidence, many of these rare variants have been labelled as pancreatitis associated. This problematic trend is notably illustrated by two recent studies that classified the p.A121T PRSS1 variant as pancreatitis associated, in large part owing to its intimate proximity to arginine-122, the residue affected by the disease causing p.R122H mutation.Here we demonstrate that the p.A121T variant is functionally innocuous and shows no verifiable association with hereditary pancreatitis, on the basis of the available inconclusive data.This case cautions that assignment of clinical relevance to rare PRSS1 variants should not be based on a perceived analogy with genuine disease causing PRSS1 mutations, and further studies are required to prove or rule out possible low penetrance causality of rare PRSS1 variants.

SUBMITTER: Szmola R

PROVIDER: S-EPMC2930840 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Uncertainties in the classification of human cationic trypsinogen (PRSS1) variants as hereditary pancreatitis-associated mutations.

Szmola Richárd R Sahin-Tóth Miklós M

Journal of medical genetics 20100501 5

<h4>Background</h4>Autosomal dominant hereditary pancreatitis has been conclusively linked with cationic trypsinogen (PRSS1) mutations p.R122H and p.N29I, which can be found in approximately 90% of mutation-positive cases. To date, 35 additional rare or private PRSS1 variants have been identified in subjects with hereditary or sporadic, idiopathic chronic pancreatitis. Despite the lack of sufficient genetic and functional evidence, many of these rare variants have been labelled as pancreatitis a ...[more]

PMID: 20452997

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Project description:Hereditary pancreatitis (HP) is an autosomal dominant disease that displays the features of both acute and chronic pancreatitis. Mutations in human cationic trypsinogen (PRSS1) are associated with HP and have provided some insight into the pathogenesis of pancreatitis, but mechanisms responsible for the initiation of pancreatitis have not been elucidated and the role of apoptosis and necrosis has been much debated. However, it has been generally accepted that trypsinogen, prematurely activated within the pancreatic acinar cell, has a major role in the initiation process. Functional studies of HP have been limited by the absence of an experimental system that authentically mimics disease development. We therefore developed a novel transgenic murine model system using wild-type (WT) human PRSS1 or two HP-associated mutants (R122H and N29I) to determine whether expression of human cationic trypsinogen in murine acinar cells promotes pancreatitis. The rat elastase promoter was used to target transgene expression to pancreatic acinar cells in three transgenic strains that were generated: Tg(Ela-PRSS1)NV, Tg(Ela-PRSS1*R122H)NV and Tg(Ela-PRSS1*N29I)NV. Mice were analysed histologically, immunohistochemically and biochemically. We found that transgene expression is restricted to pancreatic acinar cells and transgenic PRSS1 proteins are targeted to the pancreatic secretory pathway. Animals from all transgenic strains developed pancreatitis characterised by acinar cell vacuolisation, inflammatory infiltrates and fibrosis. Transgenic animals also developed more severe pancreatitis upon treatment with low-dose cerulein than controls, displaying significantly higher scores for oedema, inflammation and overall histopathology. Expression of PRSS1, WT or mutant, in acinar cells increased apoptosis in pancreatic tissues and isolated acinar cells. Moreover, studies of isolated acinar cells demonstrated that transgene expression promotes apoptosis rather than necrosis. We therefore conclude that expression of WT or mutant human PRSS1 in murine acinar cells induces apoptosis and is sufficient to promote spontaneous pancreatitis, which is enhanced in response to cellular insult.

Dataset Information

Uncertainties in the classification of human cationic trypsinogen (PRSS1) variants as hereditary pancreatitis-associated mutations.

Publications

Uncertainties in the classification of human cationic trypsinogen (PRSS1) variants as hereditary pancreatitis-associated mutations.

Similar Datasets

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