Article Text

PDF
Minigene analysis of intronic variants in common SPINK1 haplotypes associated with chronic pancreatitis
  1. É Kereszturi,
  2. O Király,
  3. M Sahin-Tóth
  1. Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, USA
  1. Dr M Sahin-Tóth, 72 East Concord Street, Evans-433; Boston, MA 02118, USA; miklos{at}bu.edu

Abstract

Background and aims: Two common haplotypes of the serine protease inhibitor Kazal type 1 (SPINK1) gene have been shown to increase the risk for chronic pancreatitis. A haplotype comprising the c.101A>G (p.N34S) missense variant and four intronic alterations has been found worldwide, whereas a second haplotype consisting of the c.−215G>A promoter variant and the c.194+2T>C intronic alteration has been observed frequently in Japan.

Methods: In the present study, the functional significance of the intronic variants in the pathogenic SPINK1 haplotypes was examined by utilising minigenes, which harbour individual introns placed in the appropriate context of the full-length SPINK1 cDNA. Cells transfected with the SPINK1 minigenes secrete active trypsin inhibitor, thereby allowing evaluation of mutational effects simultaneously on transcription, splicing, translation and secretion.

Results: It was found that the c.194+2T>C intronic alteration abolished SPINK1 expression at the mRNA level, with consequent loss of inhibitor secretion, whereas the p.N34S-associated intronic variants had no detectable functional effect.

Conclusions: Taken together with previous studies, the results indicate that all known variants within the p.N34S-associated haplotype are functionally innocuous, suggesting that an as yet unidentified variant within this haplotype is responsible for the pathogenic effect. The marked negative impact of the c.194+2T>C variant on SPINK1 expression supports the notion that SPINK1 variants increase the risk of chronic pancreatitis by diminishing protective trypsin inhibitor levels.

Statistics from Altmetric.com

Footnotes

  • Competing interests: None.

  • Funding: This work was supported by a grant from The National Pancreas Foundation to MS-T, a scholarship from the Rosztoczy Foundation to EK, and by NIH grant DK058088 to MS-T.

  • See Commentary, p 478

  • ▸ Additional figures and the full sequences of the SPINK1 minigenes are published online only at http://gut.bmj.com/content/vol58/issue4

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Linked Articles