INS-1 Cells Undergoing Caspase-Dependent Apoptosis Enhance the Regenerative Capacity of Neighboring Cells

  1. Jochen H.M. Prehn1
  1. 1Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland;
  2. 2Mater Misericordiae University Hospital, Dublin, Ireland;
  3. 3Department of Cell Physiology and Metabolism, University Medical Center, Geneva, Switzerland;
  4. 4Paris-Cardiovascular Research Centre; Institut National de la Santé et de la Recherche Médicale U970, Hopital Européen Georges Pompidou, Paris, France;
  5. 5Department of Visceral and Transplantation Surgery, University Hospital Zurich, Zurich, Switzerland.
  1. Corresponding author: Jochen H.M. Prehn, prehn{at}rcsi.ie.
  1. C.B. and S.B. contributed equally as first authors. M.M.B. and J.H.M.P. contributed equally as senior authors.

Abstract

OBJECTIVE In diabetes, β-cell mass is not static but in a constant process of cell death and renewal. Inactivating mutations in transcription factor 1 (tcf-1)/hepatocyte nuclear factor1a (hnf1a) result in decreased β-cell mass and HNF1A–maturity onset diabetes of the young (HNF1A-MODY). Here, we investigated the effect of a dominant-negative HNF1A mutant (DN-HNF1A) induced apoptosis on the regenerative capacity of INS-1 cells.

RESEARCH DESIGN AND METHODS DN-HNF1A was expressed in INS-1 cells using a reverse tetracycline-dependent transactivator system. Gene(s)/protein(s) involved in β-cell regeneration were investigated by real-time quantitative RT-PCR, Western blotting, and immunohistochemistry. Pancreatic stone protein/regenerating protein (PSP/reg) serum levels in human subjects were detected by enzyme-linked immunosorbent assay.

RESULTS We detected a prominent induction of PSP/reg at the gene and protein level during DN-HNF1A–induced apoptosis. Elevated PSP/reg levels were also detected in islets of transgenic HNF1A-MODY mice and in the serum of HNF1A-MODY patients. The induction of PSP/reg was glucose dependent and mediated by caspase activation during apoptosis. Interestingly, the supernatant from DN-HNF1A–expressing cells, but not DN-HNF1A–expressing cells treated with zVAD.fmk, was sufficient to induce PSP/reg gene expression and increase cell proliferation in naïve, untreated INS-1 cells. Further experiments demonstrated that annexin-V–positive microparticles originating from apoptosing INS-1 cells mediated the induction of PSP/reg. Treatment with recombinant PSP/reg reversed the phenotype of DN-HNF1A–induced cells by stimulating cell proliferation and increasing insulin gene expression.

CONCLUSIONS Our results suggest that apoptosing INS-1 cells shed microparticles that may stimulate PSP/reg induction in neighboring cells, a mechanism that may facilitate the recovery of β-cell mass in HNF1A-MODY.

Footnotes

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  • Received October 6, 2009.
  • Accepted July 20, 2010.

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  1. Diabetes vol. 59 no. 11 2799-2808
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