INS-1 cells undergoing caspase-dependent apoptosis enhance the regenerative capacity of neighboring cells.
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.


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.
Bonner
Caroline
C
Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland.
Bacon
Siobhán
S
Concannon
Caoimhín G
CG
Rizvi
Syed R
SR
Baquié
Mathurin
M
Farrelly
Angela M
AM
Kilbride
Seán M
SM
Dussmann
Heiko
H
Ward
Manus W
MW
Boulanger
Chantal M
CM
Wollheim
Claes B
CB
Graf
Rolf
R
Byrne
Maria M
MM
Prehn
Jochen H M
JH
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D020169:Caspases / Q000235:genetics* / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000503:physiopathology; D004797:Enzyme-Linked Immunosorbent Assay; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000235:genetics* / Q000494:pharmacology; D006801:Humans; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007340:Insulinoma / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D051538:Hepatocyte Nuclear Factor 1-alpha; D053148:Caspase 3; D020169:Caspases