Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030305 (pancreatitis)
 16,014 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Since the identification in 1996 of a "gain of function" missense mutation, R122H, in the cationic trypsinogen gene (PRSS1) as a cause of hereditary pancreatitis, continued screening of this gene in both hereditary and sporadic pancreatitis has found more disease-associated missense mutations than expected. In addition, functional analysis has yielded interesting findings regarding their underlying mechanisms resulting in a gain of trypsin. A critical review of these data, in the context of the complicated biogenesis and complex autoactivation and autolysis of trypsin(ogen), highlights that PRSS1 mutations cause the disease by various mechanisms depending on which biochemical process they affect. The discovery of these mutations also modifies the classical perception of the disease and, more importantly, reveals fascinating new aspects of the molecular evolution and normal physiology of trypsinogen. First, activation peptide of trypsinogen is under strong selection pressure to minimize autoactivation in higher vertebrates. Second, the R122 primary autolysis site has further evolved in mammalian trypsinogens. Third, evolutionary divergence from threonine to asparagine at residue 29 in human cationic trypsinogen provides additional advantage. Accordingly, we tentatively assign, in human cationic trypsinogen, the strongly selected activation peptide as the first-line and the R122 autolysis site as the second-line of the built-in defensive mechanisms against premature trypsin activation within the pancreas, respectively, and the positively selected asparagine at residue 29 as an "amplifier" to the R122 "fail-safe" mechanism.
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PMID:Molecular pathology and evolutionary and physiological implications of pancreatitis-associated cationic trypsinogen mutations. 1170 3

Over the past 5 years, several gain-of-function missense mutations in the human cationic trypsinogen gene (PRSS1, OMIM 276000) have been associated with hereditary and/or sporadic pancreatitis. This study reports a new pancreatitis-associated mutation--R116C (CGT > TGT: c.346C > T)--in the gene.
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PMID:Identification of a novel pancreatitis-associated missense mutation, R116C, in the human cationic trypsinogen gene (PRSS1). 1170 64

Hereditary pancreatitis has been found to be associated with germline mutations in the cationic trypsinogen (PRSS1) gene. Here we report a family with hereditary pancreatitis that carries a novel PRSS1 mutation (R122C). This mutation cannot be diagnosed with the conventional screening method using AflIII restriction enzyme digest. We therefore propose a new assay based on restriction enzyme digest with BstUI, a technique that permits detection of the novel R122C mutation in addition to the most common R122H mutation, and even in the presence of a recently reported neutral polymorphism that prevents its detection by the AflIII method. Recombinantly expressed R122C mutant human trypsinogen was found to undergo greatly reduced autoactivation and cathepsin B-induced activation, which is most likely caused by misfolding or disulfide mismatches of the mutant zymogen. The K(m) of R122C trypsin was found to be unchanged, but its k(cat) was reduced to 37% of the wild type. After correction for enterokinase activatable activity, and specifically in the absence of calcium, the R122C mutant was more resistant to autolysis than the wild type and autoactivated more rapidly at pH 8. Molecular modeling of the R122C mutant trypsin predicted an unimpaired active site but an altered stability of the calcium binding loop. This previously unknown trypsinogen mutation is associated with hereditary pancreatitis, requires a novel diagnostic screening method, and, for the first time, raises the question whether a gain or a loss of trypsin function participates in the onset of pancreatitis.
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PMID:Hereditary pancreatitis caused by a novel PRSS1 mutation (Arg-122 --> Cys) that alters autoactivation and autodegradation of cationic trypsinogen. 1171 9

Mutation of Arg(117), an autocatalytic cleavage site, is the most frequent amino acid change found in the cationic trypsinogen (Tg) of patients with hereditary pancreatitis. In the present study, the role of Arg(117) was investigated in wild-type cationic Tg and in the activation-resistant Lys(15) --> Gln mutant (K15Q-Tg), in which Tg-specific properties of Arg(117) can be examined selectively. We found that trypsinolytic cleavage of the Arg(117)-Val(118) bond did not proceed to completion, but due to trypsin-catalyzed re-synthesis an equilibrium was established between intact Tg and its cleaved, two-chain form. In the absence of Ca(2+), at pH 8.0, the hydrolysis equilibrium (K(hyd) = [cleaved Tg]/[intact Tg]) was 5.4, whereas 5 mm Ca(2+) reduced the rate of cleavage at Arg(117) at least 20-fold, and shifted K(hyd) to 0.7. These observations indicate that the Arg(117)-Val(118) bond exhibits properties analogous to the reactive site bond of canonical trypsin inhibitors and suggest that this surface loop might serve as a low affinity inhibitor of zymogen activation. Consistent with this notion, autoactivation of cationic Tg was inhibited by the cleaved form of K15Q-Tg, with an estimated K(i) of 80 microm, while no inhibition was observed with K15Q-Tg carrying the Arg(117) --> His mutation. Finally, zymogen breakdown due to other trypsinolytic pathways was shown to proceed almost 2000-fold slower than cleavage at Arg(117). Taken together, the findings suggest two independent, successively functional trypsin-mediated mechanisms against pathological Tg activation in the pancreas. At low trypsin concentrations, cleavage at Arg(117) results in inhibition of trypsin, whereas high trypsin concentrations degrade Tg, thus limiting further zymogen activation. Loss of Arg(117)-dependent trypsin inhibition can contribute to the development of hereditary pancreatitis associated with the Arg(117) --> His mutation.
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PMID:Human cationic trypsinogen. Arg(117) is the reactive site of an inhibitory surface loop that controls spontaneous zymogen activation. 1174 42

The recent genetic discoveries in CP support the hypothesis that inappropriate intrapancreatic activation of zymogens by trypsin results in autodigestion and pancreatitis. Two different protective mechanisms prevent activation of the pancreatic digestive enzyme cascade. First, SPINK1 inhibits up to 20% of potential trypsin activity and, second, trypsin itself activates trypsin-like enzymes readily degrading trypsinogen and other zymogens. Pancreatitis may therefore be the result of an imbalance between proteases and their inhibitors within the pancreatic parenchyma. The discovery of PRSS1 mutations in families with CP was the first breakthrough in the understanding of the underlying genetic mechanisms. Enhanced trypsinogen activation may be the common initiating step in pancreatitis caused by these mutations. The discovery of SPINK1 mutations underlines the importance of the protease inhibitor system in the pathogenesis of CP. Thus, gain-of-function in the cationic trypsinogen resulting in an enhanced autoactivation, or loss-of-function mutations in SPINK1 leading to decreased inhibitory capacity, may similarly disturb the delicate intrapancreatic balance of proteases and their inhibitors. The recent findings of SPINK1, CFTR, and PRSS1 mutations in CP patients without a family history have challenged the concept of idiopathic CP as a non-genetic disorder and the differentiation between HP and ICP. There is a clear mode of autosomal dominant inheritance for some mutations (R122H, N291, possibly MIT), whereas the inheritance pattern (autosomal recessive, complex, or modifying) of other mutations (A16V, N34S) is controverted or unknown. The lack of mutations in the above-mentioned genes in many patients suggests that CP may also be caused by genetic alterations in yet unidentified genes. Evaluation of CP patients without an obvious predisposing factor, e.g. alcohol abuse, should include genetic testing even in the absence of a family history of pancreatitis. Finally, identification of further disease-causing genes will create a better understanding of pathogenesis and may help to develop specific preventive and therapeutic strategies.
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PMID:Genetic aspects of chronic pancreatitis: insights into aetiopathogenesis and clinical implications. 1177 91

Hereditary pancreatitis is due to heterozygosity for gain-of-function mutations in the cationic trypsinogen gene which result in increased levels of active trypsin within pancreatic acinar cells and autodigestion of the pancreas. The number of disease-causing defects is generally considered to be low. To gain further insight into the molecular basis of this disorder, DNA sequence analysis of all five exons was performed in 109 unrelated patients with idiopathic chronic pancreatitis in order to determine the variability of the underlying mutations. Two German females and one German male were carriers of the most common N29I and R122H mutations (trypsinogen numbering system). In a Turkish proband, an arginine (CGT) to cysteine (TGT) substitution at amino acid position 116 was identified. Family screening demonstrated that the patient had inherited the mutation from his asymptomatic father and that he had transmitted it to both of his children, his daughter being symptomatic since the age of 3 years. In addition, a German male was found to be a heterozygote for a D100H (GAC-->CAC) amino acid replacement. Our data provide evidence for genetic heterogeneity of hereditary pancreatitis. The growing number of cationic trypsinogen mutations is expected to change current mutation screening practices for this disease.
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PMID:R116C mutation of cationic trypsinogen in a Turkish family with recurrent pancreatitis illustrates genetic microheterogeneity of hereditary pancreatitis. 1184 79

We report a 25-year-old male with hemosuccus pancreaticus associated with hereditary pancreatitis. He was originally diagnosed as having familial chronic pancreatitis at the age of 12, because his brother was also diagnosed as having pancreatitis. No history of pancreatitis was found in their parents. The patient was admitted because of a growing pancreatic pseudocyst. While he had undergone conservative treatment for the pseudocyst, computed tomography incidentally revealed a pancreatic pseudoaneurysm. Endoscopic examination revealed spontaneous bleeding from the major papilla. Interventional embolization was successfully performed. An R122H mutation in the cationic trypsinogen gene was identified in this patient, his brother, and his mother, indicating that they have hereditary pancreatitis. To our knowledge, this is the first report of hemosuccus pancreaticus associated with hereditary pancreatitis. Mutational screening is useful for the diagnosis of hereditary pancreatitis, especially in patients whose diagnosis is inconclusive based on the traditional clinical criteria.
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PMID:A case of hemosuccus pancreaticus associated with hereditary pancreatitis. 1187 52

The lysosomal cysteine protease cathepsin B is thought to play a central role in intrapancreatic trypsinogen activation and the onset of experimental pancreatitis. Recent in vitro studies have suggested that this mechanism might be of pathophysiological relevance in hereditary pancreatitis, a human inborn disorder associated with mutations in the cationic trypsinogen gene. In the present study evidence is presented that cathepsin B is abundantly present in the secretory compartment of the human exocrine pancreas, as judged by immunogold electron microscopy. Moreover, pro-cathepsin B and mature cathepsin B are both secreted together with trypsinogen and active trypsin into the pancreatic juice of patients with sporadic pancreatitis or hereditary pancreatitis. Finally, cathepsin B- catalyzed activation of recombinant human cationic trypsinogen with hereditary pancreatitis-associated mutations N29I, N29T, or R122H were characterized. In contrast to a previous report, cathepsin B-mediated activation of wild type and all three mutant trypsinogen forms was essentially identical under a wide range of experimental conditions. These observations confirm the presence of active cathepsin B in the human pancreatic secretory pathway and are consistent with the notion that cathepsin B-mediated trypsinogen activation might play a pathogenic role in human pancreatitis. On the other hand, the results clearly demonstrate that hereditary pancreatitis-associated mutations do not lead to increased or decreased trypsinogen activation by cathepsin B. Therefore, mutation-dependent alterations in cathepsin B-induced trypsinogen activation are not the cause of hereditary pancreatitis.
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PMID:Presence of cathepsin B in the human pancreatic secretory pathway and its role in trypsinogen activation during hereditary pancreatitis. 1193 57

Pancreatitis-associated gene mutations have been reported in patients with hereditary pancreatitis and idiopathic pancreatitis in the Caucasian population and involve the cationic trypsinogen gene, the pancreatic secretory trypsin inhibitor gene and the cystic fibrosis transmembrane conductance regulator gene. In the Japanese population, mutational screening analyses of these genes have shown several mutations. The present study reviews previous reports from Japan in order to evaluate the racial specificity of pancreatitis-associated gene mutations.
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PMID:Hereditary pancreatitis in Japan: a review of pancreatitis-associated gene mutations. 1212 Feb 22

Progress in understanding pancreatic diseases has been limited by a number of factors. Primary problems include the absence of good animal models, and difficulty in understanding the origin of pancreatic disease since the disease is usually manifest by the progressive destruction of the gland itself. Beginning in 1995, our laboratory, with the support of the Midwest Multicenter Pancreatic Study Group, began investigating the genetic basis of hereditary pancreatitis. Utilization of information becoming available through the human genome project allowed us to map and identify the hereditary pancreatitis gene as cationic trypsinogen (PRSS1). Molecular modeling, and subsequent experimental evidence, has solved key elements of the mysteries surrounding the origin of acute pancreatitis and the progression of acute pancreatitis to chronic pancreatitis. The availability of new genetic information and genomic tools should produce a revolution in our understanding of pancreatic diseases.
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PMID:Hereditary pancreatitis: a model for understanding the genetic basis of acute and chronic pancreatitis. 1212 Feb 37


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