INS-1 Cells Undergoing Caspase-Dependent Apoptosis Enhance the Regenerative Capacity of Neighbouring Cells
Objective: In diabetes, beta 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 beta cell mass and HNF1A-maturity-onset-diabetes-of-the-young (HNF1A-MODY). Here we investigated the effect of a dominant-negative HNF-1A mutant (DNHNF1A) 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 beta 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 ELISA. Results: We detected a prominent induction of PSP/reg at gene and protein level during DNHNF1A- 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 zVADfmk, 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 (MPs) 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. Conclusion: Our results suggest that apoptosing INS-1 cells shed microparticles that may stimulate PSP/reg induction in neighbouring cells, a mechanism that may facilitate the recovery of beta cell mass in HNF1A-MODY.
CommentsThis article is also available at http://diabetes.diabetesjournals.org
Published CitationBonner C, Bacon S, Concannon CG, Rizci SR, Baquie M, Farrelly AM, Kilbride SM, Dussmann H, Ward MW, Boulanger CM, Wollheim CB, Graf R, Byrne MM, Prehn JHM. INS-1 Cells Undergoing Caspase-Dependent Apoptosis Enhance the Regenerative Capacity of Neighbouring Cells. Diabetes 2010;59(11):2779-2808.
- Physiology and Medical Physics