University of Hertfordshire

From the same journal

By the same authors

  • Stephan C Collins
  • Hyun Woong Do
  • Benoit Hastoy
  • Alison Hugill
  • Julie Adam
  • Margarita V Chibalina
  • Juris Galvanovskis
  • Mahdieh Godazgar
  • Sheena Lee
  • Michelle Goldsworthy
  • Albert Salehi
  • Andrei I Tarasov
  • Anders H Rosengren
  • Roger Cox
  • Patrik Rorsman
View graph of relations
Original languageEnglish
Number of pages10
Pages (from-to)1952-1961
JournalDiabetes
Journal publication date30 Jun 2016
Volume65
Issue7
Early online date18 Mar 2016
DOIs
Publication statusPublished - 30 Jun 2016

Abstract

The transcription factor Sox4 has been proposed to underlie the increased type 2 diabetes risk linked to an intronic single nucleotide polymorphism in CDKAL1 In a mouse model expressing a mutant form of Sox4, glucose-induced insulin secretion is reduced by 40% despite normal intracellular Ca(2+) signaling and depolarization-evoked exocytosis. This paradox is explained by a fourfold increase in kiss-and-run exocytosis (as determined by single-granule exocytosis measurements) in which the fusion pore connecting the granule lumen to the exterior expands to a diameter of only 2 nm, which does not allow the exit of insulin. Microarray analysis indicated that this correlated with an increased expression of the exocytosis-regulating protein Stxbp6. In a large collection of human islet preparations (n = 63), STXBP6 expression and glucose-induced insulin secretion correlated positively and negatively with SOX4 expression, respectively. Overexpression of SOX4 in the human insulin-secreting cell EndoC-βH2 interfered with granule emptying and inhibited hormone release, the latter effect reversed by silencing STXBP6 These data suggest that increased SOX4 expression inhibits insulin secretion and increased diabetes risk by the upregulation of STXBP6 and an increase in kiss-and-run exocytosis at the expense of full fusion. We propose that pharmacological interventions promoting fusion pore expansion may be effective in diabetes therapy.

Notes

© 2016 by the American Diabetes Association

ID: 15266988