Pancreatic Secretory Trypsin Inhibitor Gene Research Articles

Mutations in the pancreatic secretory trypsin inhibitor (SPINKI1/PSTI) gene in Japanese patients with pancreatitis

Mutations in the pancreatic secretory trypsin inhibitor (SPINKI1/PSTI) gene in Japanese patients with pancreatitis

Cationic trypsinogen and pancreatic secretory trypsin inhibitor gene mutations in neonatal hypertrypsinaemia

Neonatal hypertrypsinaemia with normal sweat chloride detected during CF screening may be related to trypsin activation. We have looked for mutations of the cationic trypsinogen (PRSS1) and pancreatic secretory trypsin inhibitor (PSTI) genes in 50 hypertrypsinaemic neonates with known CFTR genotypes and negative sweat test. No mutations were found in either gene. Two silent polymorphisms were detected in the PRSS1 gene. A polymorphism in the promoter region and an intronic polymorphism of the PSTI gene were found. No difference was observed in the frequency of PRSS1 or PSTI polymorphisms in neonates carrying or not carrying CF mutations. These results do not provide an indication for an increased frequency of mutations in the PRSS1 and PSTI genes in this group of neonates with transient hypertrypsinaemia.

Motion-Genetic Testing is Useful in the Diagnosis of Nonhereditary Pancreatic Conditions: Arguments Against the Motion

Mutations of two genes, the cystic fibrosis transmembrane conductance regulator gene (CFTR) and the pancreatic secretory trypsin inhibitor gene (PSTI), are associated with an increase in the risk of idiopathic chronic pancreatitis. Persons who have mutations of both CFTR alleles (one severely and one mildly affected) are especially susceptible to this disease. Because these compound heterozygotes have sufficient residual CFTR function, they do not develop cystic fibrosis lung disease. One PSTI mutation, N34S, independently increases the risk of pancreatitis. Thus, the risk of pancreatitis is greatest among individuals who are CFTR compound heterozygotes and who also have the PSTI mutation. Nonetheless, most people with CFTR and PSTI mutations do not develop pancreatitis. This fact indicates that environmental influences and gene-gene interactions also affect pancreatitis risk. Although CFTR and PSTI genetic testing can identify persons at an increased risk of pancreatitis, there are several reasons why the routine screening of individuals with nonhereditary pancreatitis is not recommended at this time: most disease-associated mutations are not detected by readily available techniques, genetic counselling guidelines do not exist, most patients with mutations do not develop pancreatitis and the results of testing do not affect the clinical management of pancreatitis.

Functional analysis of recombinant pancreatic secretory trypsin inhibitor protein with amino-acid substitution.

We hypothesized that mutation of the pancreatic secretory trypsin inhibitor ( PSTI) gene may promote a predisposition to pancreatitis, possibly by reducing the inhibition of trypsin activity. Based on this hypothesis, we performed a biochemical analysis of recombinant PSTI protein. The trypsin inhibitory activity of the recombinant protein was analyzed. The activity of PSTI protein with a point mutation of the most common type: (34)Asn (AAT)-to-Ser (AGT)(101A>G N34S: N34S) in exon 3, was compared with that of the wild type. The function of N34S PSTI remained unchanged under both the usual alkaline and acidic conditions compared with the wild-type PSTI. The calcium concentration did not affect the activity of recombinant PSTI. The trypsin susceptibility of the N34S protein was not increased either. Mechanisms other than the conformational change of PSTI associated with amino-acid substitution, such as abnormal splicing, may underlie the predisposition to pancreatitis in patients with the N34S mutation.

Genetics and pancreatic disease

The recognition that variations in the DNA sequence of key genes predispose individuals to acute pancreatitis, chronic pancreatitis, and pancreatic cancer represents one of the greatest breakthroughs in pancreas research. This review highlights recent progress in understanding mutations in the cationic trypsinogen gene, the pancreatic secretory trypsin inhibitor gene, and the cystic fibrosis transmembrane conductance regulator gene with respect to pancreatitis. It also notes progress in the use of microarray technology, classification of chronic pancreatitis, and predisposition to pancreatic cancer.

The N34S mutation of SPINK1 (PSTI) is associated with a familial pattern of idiopathic chronic pancreatitis but does not cause the disease.

Mutations in the PRSS1 gene explain most occurrences of hereditary pancreatitis (HP) but many HP families have no PRSS1 mutation. Recently, an association between the mutation N34S in the pancreatic secretory trypsin inhibitor (SPINK1 or PSTI) gene and idiopathic chronic pancreatitis (ICP) was reported. It is unclear whether the N34S mutation is a cause of pancreatitis per se, whether it modifies the disease, or whether it is a marker of the disease. A total of 327 individuals from 217 families affected by pancreatitis were tested: 152 from families with HP, 108 from families with ICP, and 67 with alcohol related CP (ACP). Seven patients with ICP had a family history of pancreatitis but no evidence of autosomal dominant disease (f-ICP) compared with 87 patients with true ICP (t-ICP). Two hundred controls were also tested for the N34S mutation. The findings were related to clinical outcome. The N34S mutation was carried by five controls (2.5%; allele frequency 1.25%), 11/87 (13%) t-ICP patients (p=0.0013 v controls), and 6/7 (86%) affected (p<0.0001 v controls) and 1/9 (11%) unaffected f-ICP cases. N34S was found in 4/108 affected HP patients (p=0.724 v controls), in 3/27 (11%) with wild-type and in 1/81 (1%) with mutant PRSS1, and 4/67 ACP patients (all p>0.05 v controls). The presence of the N34S mutation was not associated with early disease onset or disease severity. The prevalence of the N34S mutation was increased in patients with ICP and was greatest in f-ICP cases. Segregation of the N34S mutation in families with pancreatitis is unexplained and points to a complex association between N34S and another putative pancreatitis related gene.

Determination of the relative contribution of three genes-the cystic fibrosis transmembrane conductance regulator gene, the cationic trypsinogen gene, and the pancreatic secretory trypsin inhibitor gene-to the etiology of idiopathic chronic pancreatitis.

In the last 5 years, mutations in three genes, the cystic fibrosis transmembrane conductance regulator (CFTR) gene, the cationic trypsinogen (PRSS1) gene, and the pancreatic secretory trypsin inhibitor (PSTI) gene, have been found to be associated with chronic pancreatitis (CP). In this study, using established mutation screening methods, we systematically analysed the entire coding sequences and all exon/intron junctions of the three genes in 39 patients with idiopathic CP (ICP), with a view to evaluating the relative contribution of each gene to the aetiology of the disease. Our results demonstrate that, firstly, 'gain-of-function' mutations in the PRSS1 gene may occasionally be found in an obvious ICP subject. Secondly, presumably 'loss-of-function' mutations in the PSTI gene appear to be frequent, with a detection rate of at least 10% in ICP and, finally, abnormal CFTR alleles are common: at least 20% of patients carried one of the most common CFTR mutations, and about 10% of patients were compound heterozygotes, having at least one 'mild' allele. Thus, in total, about 30% of ICP patients carried at least one abnormal allele in one of the three genes, and this is the most conservative estimate. Moreover, a trans-heterozygous state with sequence variations in the PSTI/CFTR genes was found in three patients. However, an association between the 5T allele in intron 8 of the CFTR gene and ICP remains unproven.

Genetic mutations in exons 3 and 4 of the pancreatic secretory trypsin inhibitor in patients with pancreatitis.

We hypothesized that mutations in the pancreatic secretory trypsin inhibitor (PSTI) gene could promote autodigestion, leading to acute or chronic pancreatitis. Our investigation involved mutation analysis of the PSTI gene in patients with acute or chronic pancreatitis. Mutation analysis for the PSTI gene was performed in patients with acute or chronic pancreatitis. Unrelated healthy volunteers and family members of a chronic pancreatitis patient with point mutations in the PSTI gene were also analyzed. Two types of single-point mutation in the PSTI gene were observed in one patient with chronic pancreatitis: 34Asn (AAT)-to-Ser (AGT) (101 A > G N34S: N34S) in exon 3, and 67Arg (CGC)-to-Cys (TGC) (199 C > T R67C: R67C) in exon 4. No mutations with amino-acid substitution were found in other patients or in the volunteer group. In the patient with the PSTI gene mutations, no additional mutations were observed in the cationic trypsinogen gene. The family study revealed that the mother and a maternal uncle were homozygotes for the N34S mutation, while the father and brother were compound heterozygotes for the N34S and R67C mutations. The uncle (N34S/N34S) showed clinical manifestations of pancreatitis, but the other family members did not. The N34S mutation may cause a predisposition to pancreatitis, with incomplete penetrance. However, with the limited information available, it is not known whether the R67C mutation promotes pancreatitis.

Analysis of the human pancreatic secretory trypsin inhibitor (PSTI) gene mutations in Japanese patients with chronic pancreatitis.

Chronic pancreatitis (CP) is a continuing or relapsing inflammatory disease of the pancreas. Several studies have demonstrated that mutations in the cationic trypsinogen (PRSS1) gene and the cystic fibrosis transmembrane conductance regulator (CFTR) gene are causative of the pathogenesis in a subset of hereditary and/or idiopathic CP cases. Recently, the N34S alteration of the pancreatic secretory trypsin inhibitor (PSTI) gene has been suggested to be closely associated with the pathogenesis of hereditary and/or idiopathic CP. Herein we analyzed genetic alterations of the PSTI gene in 32 unrelated Japanese CP patients who developed juvenile-onset CP or had a family history of CP; 5 patients were found to harbor alterations in this gene. In 3 of these 5 patients, heterozygous N34S alterations were found; this frequency is significantly lower than that in Caucasian patients reported previously. Moreover, a novel homozygous G-to-A transition in the promoter region of PSTI at 215bp upstream from the translation initiation site (-215G>A) was observed in 2 patients. We further surveyed the -215G>A alteration in 117 normal individuals; none of these individuals harbored this alteration. Our results suggested that the -215G>A alteration, as well as the N34S alteration, is a predisposing factor for CP.

Mutations of the pancreatic secretory trypsin inhibitor (PSTI) gene in idiopathic chronic pancreatitis

GASTROENTEROLOGY 2001;120:1061-1063

Identification of Novel Pancreas-specific Regulatory Sequences in the Promoter Region of Human Pancreatic Secretory Trypsin Inhibitor Gene

The human pancreatic secretory trypsin inhibitor (PSTI) genes introduced into mice are specifically expressed in pancreas. The 1.0 kilobase pairs of PSTI 5'-flanking sequence directed preferential expression of a linked reporter chloramphenicol acetyltransferase, which was active in a PSTI-expressing pancreatic cell line (AR42j) but not in a PSTI-nonexpressing fibroblast cell line (XC). Two positively acting elements were found, Region I (-161/-116) and Region II (-103/-74), as defined by transfection and binding assays with AR42j cells. Region II is sufficient for the pancreas-specific expression, but the presence of both Regions I and II is needed for the maximum activity. Sequence studies also revealed that these two elements differ from the previously identified recognition sequence for pancreas transcription factor 1 (PTF1). When the same set of experiments was done with XC cells, one negatively acting element was identified, Region IV (-154/-137). Interestingly, Regions I and IV share a core sequence (-149/-139), CAATCAATAAC. These results suggest that this novel element regulates the human PSTI gene expression positively in pancreatic cells but negatively in nonpancreatic cells.

Correlated regulation of the mRNAs encoding secretory trypsin inhibitors and anionic trypsinogen I in the rat pancreas depending on the dietary protein intake

Tissue and mRNA levels of trypsin and the two forms of pancreatic secretory trypsin inhibitor (PSTI) were determined in the pancreatic tissue of rats fed on either a protein-free diet or two high-protein diets (44% and 64% protein, respectively) for 10 days as compared with control rats fed on a standard diet (22% protein). Two distinct response patterns were obtained, depending on the animals' nutritional status after ingestion of the protein-free and high-protein diets. After administration of the protein-free diet (containing 81% carbohydrate), the levels of the two mRNAs encoding both forms of the secretory trypsin inhibitor and anionic trypsinogen I increased significantly (100%, 110%, and 110%, respectively), whereas no significant increase in both PSTI mRNA levels were observed after the ingestion of the high-protein diets as compared with the control rats. Under all three dietary conditions, a coordinated pattern of response was observed between the two forms of inhibitors and anionic trypsinogen I at both the tissue mRNA and protein levels. The existence of a parallel change in trypsin activity and secretory trypsin inhibitor activity on the one hand, and trypsin mRNA and inhibitor mRNAs on the other hand, suggests that indentical influences regulate the expression of trypsin and pancreatic secretory trypsin inhibitor genes in response to the dietary protein content.

Pancreatic secretory trypsin inhibitor gene is highly expressed in the liver of adult-onset type II citrullinemia

Deficiency of argininosuccinate synthetase (ASS) causes citrullinemia. Type II citrullinemia is found in most patients with adult-onset citrullinemia in Japan, and ASS is deficient specifically in the liver. Previous studies have shown that the decrease of hepatic ASS activity is caused by a decrease in enzyme protein with normal kinetic properties and that there are no apparent abnormalities in the amount, translational activity, and nucleotide sequence of hepatic ASS mRNA. Recent results of homozygosity testing indicate that the primary defect of type II citrullinemia is not within the ASS gene locus. In this present work, to understand the pathogenesis and pathophysiology of type II citrullinemia, we have characterized the alterations of gene expression in the liver of type II patients using the recently developed mRNA differential display method. Some cDNA bands expressed differently in type II citrullinemia patients and control were selected, cloned, and sequenced. Nucleotide sequence analysis and homology searching revealed an interesting clone which has 99% homology with the human pancreatic secretory trypsin inhibitor (hPSTI). Northern blot and RT-PCR analyses showed that the expression of hPSTI mRNA increased significantly in the liver of all type II patients tested. Furthermore, the concentration of hPSTI protein was found to be higher in the liver of type II citrullinemia than in control. These results suggest that hPSTI may be related to the primary defect of type II citrullinemia and may be useful as a diagnostic marker, although the detailed mechanism of the high expression of hPSTI mRNA in type II liver is not yet known.

Expression of the pancreatic secretory trypsin inhibitor gene in the liver infected with hepatitis B virus

Pancreatic secretory trypsin inhibitor, an acute phase reactant protein, is expressed in the liver in response to inflammatory cytokines, especially in hepatocellular carcinoma. Northern blots of 25 dissected liver tissues from non-hepatitis, chronic hepatitis and cirrhosis patients revealed that 10 (40%) expressed pancreatic secretory trypsin inhibitor. The expression seemed to be closely associated with hepatitis B viral infection, since among the 11 hepatitis B virus-infected samples, nine (81%) were pancreatic secretory trypsin inhibitor-positive. In contrast, this augmented expression was absent in non-infected livers (0/5; 0%), and rare in those infected with hepatitis C virus (1/9; 11%). There was no significant correlation between the pancreatic secretory trypsin inhibitor expression in the liver and the serum level of glutamic pyruvic transaminase, the hepaplastin test, the 15-min retention rate of indocyanine green, or the histological findings of the liver tissues such as lymphocyte infiltration and pseudolobular formation. Furthermore, we identified an almost three-fold increase in the transactivation of pancreatic secretory trypsin inhibitor gene expression in HepG2 cells after transient transfection with HBV-DNA or the X gene in an expression vector. These results suggest that the induction of pancreatic secretory trypsin inhibitor gene expression in livers with chronic hepatitis and cirrhosis is directly affected by hepatitis B virus.

Specific expression of the pancreatic‐secretory‐trypsin‐inhibitor (PSTI) gene in hepatocellular carcinoma

Twenty hepatocellular carcinomas (HCC) were analyzed by Northern blotting to test the expression of pancreatic secretory trypsin inhibitor (PSTI). This gene was expressed in all HCCs, but not in other tumors, including mammary, thyroid, pulmonary and ovarian cancers. Some gastric and colonic cancers weakly expressed PSTI. Among cell lines examined in a similar manner, PSTI was expressed in all of 4 derived from hepatoma. On the other hand, among 15 cell lines derived from cancers other than hepatoma, only 3, derived from pancreatic, colonic and gastric cancers, weakly expressed PSTI. A CAT assay using a deletion set of the 5' region from the cloned PSTI gene has shown that in hepatoma cell lines, the expression of this gene is dependent on the presence of 2 regulatory regions that include an IL-6 responsive elements and an AP-I-binding site. However, in non-hepatoma cell lines, the 2 regulatory regions are not necessary for expression. The blood level of PSTI in 27 patients with HCC was significantly increased, and it was positively correlated with tumor size, suggesting that specific expression of PSTI in HCC causes this effect and that elevated blood level of PSTI without inflammation indicates the presence of HCC.

Identification of the IL-6-responsive element in an acute-phase-responsive human pancreatic secretory trypsin inhibitor-encoding gene

Pancreatic secretory trypsin inhibitor (PSTI) has been suggested to be an acute-phase reactant in humans and to be induced by inflammatory cytokines such as the interleukins IL-1 and IL-6. We report that PSTI is synthesized in hepatoma cells and that the gene expression is augmented by IL-6. The start points (tsp) for basal and augmented transcription are exactly the same as the tsp in normal pancreas. Analysis of the PSTI gene revealed that a 40-bp DNA fragment located between kb −3.84 and −3.80 carries the element responsible for both basal transcriptional activity and IL-6-induced gene expression. This 40-bp fragment contains T G TNNGNAA G T, the consensus sequence for the NF-IL6-binding site, which is also known as the IL-6-responsive element that is conserved among various acute-phase genes. The basal activity was augmented by another sequence that lies between kb −4.0 and −3.9.

Expression of pancreatic secretory trypsin inhibitor gene in human colorectal tumor

Expression of pancreatic secretory trypsin inhibitor (PSTI) gene was examined by Northern blotting analyses in 31 human colorectal tumors that included two benign adenomas and 26 adenocarcinomas. Among the total of 28 cases which proved to be adequate for mRNA analyses, all but one showed the expression of PSTI at various levels. In contrast, PSTI expression was not detected in two malignant lymphomas of the rectum. The level of PSTI expression was not correlated with the patient's age, sex, tumor location or size, stage of differentiation, lymph node metastasis, or progression stage. Some colorectal adenocarcinomas were also shown to express genes that can hybridize with human trypsinogen cDNA probe. It looks as though in these tumors, a protease(s) and its inhibitor are produced simultaneously as part of a cellular self-defense mechanism.

Expression of pancreatic secretory trypsin inhibitor gene in human colorectal tumor

Expression of pancreatic secretory trypsin inhibitor gene in human colorectal tumor

Expression of pancreatic secretory trypsin inhibitor gene in neoplastic tissues

Expression of the human pancreatic secretory trypsin inhibitor (PSTI) gene was examined in 24 cases of neoplastic tissues by Northern blot analyses. In three cases of lung adenocarcinoma and one case of sigmoid colon polyp, we detected transcripts which hybridized to the human PSTI cDNA probe. cDNA libraries were constructed using mRNAs of the two PSTI-positive tumor tissues. Two PSTI cDNA clones were obtained from each sample. Sequencing analyses showed that they were completely identical with that of pancreatic PSTI cDNA which had been reported [(1985) Biochem. Biophys. Res. Commun. 132, 605–612]. Southern blot analyses showed that the elevated expression of PSTI in neoplastic tissues was accompanied by neither PSTI gene amplification nor rearrangements.

Primary structure of human pancreatic secretory trypsin inhibitor (PSTI) gene

The human pancreatic secretory trypsin inhibitor (PSTI) gene was isolated from a human gene library. Restriction endonuclease mapping and DNA sequencing analysis revealed that this gene is approximately 7.5 kb long and is separated into four exons by three introns. The gene has multiple transcription start points and examination with a single-laser cell-sorter showed that it is located on chromosome 5.