Signal peptide variants that impair secretion of pancreatic secretory trypsin inhibitor (SPINK1) cause autosomal dominant hereditary pancreatitis.
Variants of the SPINK1 gene encoding pancreatic secretory trypsin inhibitor have been described in association with chronic pancreatitis (CP). These alterations are believed to cause a loss of function by either impairing the trypsin inhibitory activity or reducing expression. Here we report two novel SPINK1 variants in exon 1 that affect the secretory signal peptide. The disease-associated c.41T>G (p.L14R) alteration was found in two European families with autosomal dominant hereditary pancreatitis, whereas the c.36G>C (p.L12F) variant was identified as a frequent alteration in subjects of African descent. The functional effects of both alterations and the previously reported c.41T>C (p.L14P) variant were characterized by activity assays and Western blots of wild-type and mutant SPINK1 expressed in human embryonic kidney 293T and Chinese hamster ovary cells. Alterations p.L14R and p.L14P destined the inhibitor for rapid intracellular degradation and thereby abolished SPINK1 secretion, whereas the p.L12F variant showed no detrimental effect. The results provide the first clear experimental demonstration that alterations that markedly reduce SPINK1 expression are associated with classic hereditary pancreatitis. Therefore, these variants should be classified as severe and regarded as disease-causing rather than disease-modifiers.
Király
Orsolya
O
Department of Molecular and Cell Biology, Boston University, Goldman School of Dental Medicine, Boston, Massachusetts, USA.
Boulling
Arnaud
A
Witt
Heiko
H
Le Maréchal
Cédric
C
Chen
Jian-Min
JM
Rosendahl
Jonas
J
Battaggia
Cinzia
C
Wartmann
Thomas
T
Sahin-Tóth
Miklós
M
Férec
Claude
C
D000293:Adolescent; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D016466:CHO Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002648:Child; D006224:Cricetinae; D003412:Cricetulus; D017931:DNA Primers; D005260:Female; D005799:Genes, Dominant; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010195:Pancreatitis / Q000235:genetics*; D010375:Pedigree; D021382:Protein Sorting Signals / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014359:Trypsin Inhibitor, Kazal Pancreatic
D002352:Carrier Proteins; D017931:DNA Primers; D021382:Protein Sorting Signals; C486642:SPINK1 protein, human; D014359:Trypsin Inhibitor, Kazal Pancreatic