Sequence Analysis of the Human Tyrosylprotein Sulfotransferase-2 Gene in Subjects with Chronic Pancreatitis

Abstract

Background/Aims: Human trypsinogens are post-translationally sulfated on Tyr154 by the Golgi resident enzyme tyrosylprotein sulfotransferase-2 (TPST2). Tyrosine sulfation stimulates the autoactivation of human cationic trypsinogen. Because increased trypsinogen autoactivation has been implicated as a pathogenic mechanism in chronic pancreatitis, we hypothesized that genetic variants of TPST2 might alter the risk for the disease. Methods: We sequenced the 4 protein-coding exons and the adjacent intronic sequences of TPST2 in 151 subjects with chronic pancreatitis and in 169 healthy controls. The functional effect of TPST2 variants on trypsinogen sulfation was analyzed in transfected HEK 293T cells. Results: We detected 10 common polymorphic variants, including 6 synonymous variants and 4 intronic variants, with similar frequencies in patients and controls. None of the 8 common haplotypes reconstructed from the frequent variants showed an association with chronic pancreatitis. In addition, we identified 5 rare TPST2 variants, which included 3 synonymous alterations, the c.458G>A (p.R153H) nonsynonymous variant and the c.-9C>T variant in the 5′ untranslated region. The p.R153H variant was found in a family with hereditary pancreatitis; however, it did not segregate with the disease. In functional assays, both the p.R153H and c.-9C>T TPST2 variants catalyzed trypsinogen sulfation as well as wild-type TPST2. Conclusion: Genetic variants of human TPST2 exert no influence on the risk of chronic pancreatitis.

Tyrosine Sulfation of Human Trypsin Steers S2’ Subsite Selectivity towards Basic Amino Acids

“…Autoactivation of human cationic trypsinogen was somewhat increased by sulfation but a similar effect was not observed with anionic trypsinogen [6] , [8] . Increased trypsinogen autoactivation has been implicated as a pathogenic mechanism in chronic pancreatitis, but a genetic study analyzing human TPST2 variants found no association with chronic pancreatitis [13] . More detailed comparative analysis of non-sulfated and sulfated anionic trypsins did not reveal any appreciable differences with respect to catalytic activity on a variety of substrates, activation by enteropeptidase, proteolytic stability or cellular expression [8] .…”