Hereditary pancreatitis caused by mutation-induced misfolding of human cationic trypsinogen: a novel disease mechanism.
We investigated the biochemical properties and cellular expression of the c.346C>T (p.R116C) human cationic trypsinogen (PRSS1) mutant, which we identified in a German family with autosomal dominant hereditary pancreatitis. This mutation leads to an unpaired Cys residue with the potential to interfere with protein folding via incorrect disulfide bond formation. Recombinantly expressed p.R116C trypsinogen exhibited a tendency for misfolding in vitro. Biochemical analysis of the correctly folded, purified p.R116C mutant revealed unchanged activation and degradation characteristics compared to wild type trypsinogen. Secretion of mutant p.R116C from transfected 293T cells was reduced to approximately 20% of wild type. A similar secretion defect was observed with another rare PRSS1 variant, p.C139S, whereas mutants p.A16V, p.N29I, p.N29T, p.E79K, p.R122C, and p.R122H were secreted normally. All mutants were detected in cell extracts at comparable levels but a large portion of mutant p.R116C was present in an insoluble, protease-sensitive form. Consistent with intracellular retention of misfolded trypsinogen, the endoplasmic reticulum (ER) stress markers immunoglobulin-binding protein (BiP) and the spliced form of the X-box binding protein-1 (XBP1s) were elevated in cells expressing mutant p.R116C. The results indicate that mutation-induced misfolding and intracellular retention of human cationic trypsinogen causes hereditary pancreatitis in carriers of the p.R116C mutation. ER stress triggered by trypsinogen misfolding represents a new potential disease mechanism for chronic pancreatitis.
Kereszturi
Eva
E
Department of Molecular and Cell Biology, Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA.
Szmola
Richárd
R
Kukor
Zoltán
Z
Simon
Peter
P
Weiss
Frank Ulrich
FU
Lerch
Markus M
MM
Sahin-Tóth
Miklós
M
D000328:Adult; D000368:Aged; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D002648:Child; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005192:Family Health; D005260:Female; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010195:Pancreatitis / Q000235:genetics* / Q000378:metabolism; D010375:Pedigree; D017510:Protein Folding; D000071701:Regulatory Factor X Transcription Factors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014357:Trypsin; D014362:Trypsinogen / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000071717:X-Box Binding Protein 1
D004268:DNA-Binding Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D050505:Mutant Proteins; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human; D014362:Trypsinogen; C489303:PRSS1 protein, human; D014357:Trypsin