Evolutionary expansion of poly-aspartate motif in the activation peptide of mouse cationic trypsinogen limits autoactivation and protects against pancreatitis

The activation peptide of mammalian trypsinogens typically contains a tetra-aspartate motif (positions P2-P5 in Schechter-Berger numbering) that inhibits autoactivation and facilitates activation by enteropeptidase. This evolutionary mechanism protects the pancreas from premature trypsinogen activation while allowing physiological activation in the gut lumen. Inborn mutations that disrupt the tetra-aspartate motif cause hereditary pancreatitis in humans. A subset of trypsinogen orthologs, including the mouse cationic trypsinogen (isoform T7), harbor an extended penta-aspartate motif (P2-P6) in their activation peptide. Here, we demonstrate that deletion of the extra P6 aspartate residue (D23del) increased autoactivation of T7 trypsinogen 3-fold. Mutagenesis of the P6 position in wild-type T7 trypsinogen revealed that bulky hydrophobic side-chains are preferred for maximal autoactivation and deletion-induced shift of the P7 Leu to P6 explains the autoactivation increase in the D23del mutant. Accordingly, removal of the P6 Leu by N-terminal truncation with chymotrypsin C reduced autoactivation of the D23del mutant. Homozygous T7D23del mice carrying the D23del mutation did not develop spontaneous pancreatitis and severity of cerulein-induced acute pancreatitis was comparable to that of C57BL/6N controls. However, sustained stimulation with cerulein resulted in markedly increased histological damage in T7D23del mice relative to C57BL/6N mice. Furthermore, when the T7D23del allele was crossed to a chymotrypsin-deficient background, the double-mutant mice developed spontaneous pancreatitis at an early age. Taken together, the observations argue that evolutionary expansion of the poly-aspartate motif in mouse cationic trypsinogen contributes to the natural defenses against pancreatitis and validate the role of the P6 position in autoactivation control of mammalian trypsinogens.

Possibilities of the early diagnosis and prognosis of complicated clinical forms of chronic pancreatitis

AIM: This study aimed to improve the methods for the diagnosis of complicated clinical forms of chronic pancreatitis (CP) by evaluating the clinical significance of the polymorphisms of the genes of cationic trypsinogen (PRSS1), pancreatic secretory trypsin inhibitor (SPINK1), transmembrane regulator of cystic fibrosis (CFTR), and alcohol dehydrogenase (ADH) in patients with complicated and uncomplicated forms of CP. MATERIALS AND METHODS: The study was carried out on the clinical base of the Department of Hospital Surgery, Ryazan State Medical University, Center for Surgery of Liver, Pancreas, and Biliary Tract in Ryazan in 20142019. A total of 108 patients of both genders aged 2565 years were examined. Of these patients, 38 were surgically treated for complicated CP, 20 had complicated CP without surgery, and 50 had uncomplicated CP (control group). A comparative clinical study with the control group of patients was performed, and the genotype was simultaneously determined on days 1 and 10 under controlled laboratory parameters. DNA was isolated from the leukocytes of the whole blood by using a DNA-expressing blood reagent (OOO NPF Litekh, Russia) for further analysis. RESULTS: No polymorphism of cationic trypsinogen PRSS1 gene and cystic fibrosis-2 CFTR2 gene was found. The predictive value of these polymorphisms was insignificant. For the polymorphism of CFTR1 cystic fibrosis-1 gene, the odds ratio was 0.444, but this finding was not significant. Among patients with the complicated clinical forms of CP, mutations were observed in the PRSS1 cationic trypsinogen gene (c2 = 6.453, p = 0.012) and ADH (c2=14.176, p = 0.001). Conversely, they were not detected in the CFTR-1 gene (c2 = 0.873, p = 0.351), CFTR-2 (c2 was not determined), and SPINK1 (c2 = 0.873, p = 0.351). The polymorphisms of the ADH and PRSS1 genes of cationic trypsinogen were associated with more evident structural changes in the parenchyma and ductal system of the pancreas. They also had a higher likelihood of complications, severe disease course, and a lower efficiency of conservative treatment. The polymorphism of the ADH gene increased the risk of the development of the cystic form of CP (c2 = 5.898, p = 0.016). CONCLUSION: The polymorphism of ADH and cationic trypsinogen genes should be determined and used for the complex diagnosis of CP to specify indications for the surgical treatment of patients with CP.

Genetic Abnormalities in Pancreatitis: An Update on Diagnosis, Clinical Features, and Treatment

Several pancreatitis susceptibility genes have been identified to date. A relationship between a mutation in the cationic trypsinogen (protease serine 1, PRSS1) gene and hereditary pancreatitis (HP) was first identified in 1996. Currently, HP has been defined as either two or more individuals within a family exhibiting pancreatitis for two or more generations, or pancreatitis linked to mutation of the PRSS1 gene. In 2000, a mutation in the serine protease inhibitor gene (Kazal type 1: SPINK1) was reported to be related to sporadic pancreatitis of unknown etiology. This paper reviews and summarizes the current published data on the pancreatitis susceptibility genes, mainly PRSS1 and SPINK1 genes, and introduces a diagnostic and therapeutic approach for dealing with patients with these gene mutations. Patients with these genetic predispositions, both children and adults, have often been initially diagnosed with idiopathic acute pancreatitis, in approximately 20–50% of pediatric cases and 28–80% of adult cases. In such patients, where the etiology is unknown, genetic testing, which requires pre-test and post-test genetic counselling, may prove helpful. Patients with chronic pancreatitis (CP) due to SPINK1 gene mutation and HP patients have a potentially high risk of pancreatic exocrine insufficiency, diabetes mellitus, and, of particular importance, pancreatic cancer. Thus, these patients require careful long-term follow-up and management. Specifically, symptomatic CP patients often need endoscopic therapy or surgery, often following a step-up approach beginning with endoscopic therapy and progressing to surgery if necessary, which is similar to the therapeutic approach for patients with CP due to other etiologies. It is important that clinicians are aware of the characteristics of patients with pancreatitis susceptibility genetic abnormalities.

PRSS1 mutation: a possible pathomechanism of pancreatic carcinogenesis and pancreatic cancer

Background Previous studies revealed somatic mutations of the cationic trypsinogen gene (PRSS1) in patients with chronic pancreatitis and pancreatic cancer. However, whether PRSS1 mutations trigger pancreatic cancer and/or promote malignant proliferation and metastasis in pancreatic cancer remains largely unclear, as well as the potential underlying mechanisms. Methods In the present study, whole-exome sequencing was applied for screening, and the R116C mutation was validated by Sanger sequencing. Phosphorylation antibody array, RNA-Seq, and RT-qPCR were adopted to screen and validate that R116C mutation promoted pancreatic cancer progression via the JAK1-STAT5 pathway. Results It showed that migration and invasion were significantly increased in R116C-bearing PANC-1 cells compared with wild type counterparts. In a transgenic mouse model of iZEG-PRSS1_R116C, primary pancreatic intraepithelial neoplasia (PanINs) was observed in the pancreatic duct. Conclusions These findings suggested a novel pathway mediating pancreatic cancer development, with PRSS1 mutation and overexpression playing an “inside job” role in pancreatic carcinogenesis and tumor development.

Hereditary pancreatitis: tactics of diagnostics and differential diagnostics (clinical case)

The article presents a literature review on the main genetic mutations leading to the development of pancreatitis, analyzes the pathogenesis of hereditary pancreatitis and the high risk of pancreatic cancer upon this disease. The authors described their own clinical case of calcificating pancreatitis that developed in a patient with a mutation of the cationic trypsinogen gene. The tactics of treatment and observation is discussed.

The Differential Role of Human Cationic Trypsinogen (PRSS1) p.R122H Mutation in Hereditary and Nonhereditary Chronic Pancreatitis: A Systematic Review and Meta-Analysis

Background. Environmental factors and genetic mutations have been increasingly recognized as risk factors for chronic pancreatitis (CP). ThePRSS1p.R122H mutation was the first discovered to affect hereditary CP, with 80% penetrance. We performed here a systematic review and meta-analysis to evaluate the associations ofPRSS1p.R122H mutation with CP of diverse etiology.Methods. The PubMed, EMBASE, and MEDLINE database were reviewed. The pooled odds ratio (OR) with 95% confidence intervals was used to evaluate the association of p.R122H mutation with CP. Initial analysis was conducted with all etiologies of CP, followed by a subgroup analysis for hereditary and nonhereditary CP, including alcoholic or idiopathic CP.Results. A total of eight case-control studies (1733 cases and 2415 controls) were identified and included. Overall,PRSS1p.R122H mutation was significantly associated with an increased risk of CP (OR = 4.78[1.13–20.20]). Further analysis showed p.R122H mutation strongly associated with the increased risk of hereditary CP (OR = 65.52[9.09–472.48]) but not with nonhereditary CP, both alcoholic and idiopathic CP.Conclusions. Our study showing the differential role of p.R122H mutation in various etiologies of CP indicates that this complex disorder is likely influenced by multiple genetic factors as well as environmental factors.