Cobalt protoporpyhrin reduces caspase-3,-7 enzyme activity in neonatal porcine islets, but does not inhibit cell death induced by TNF-alpha.
Apoptotic phenomena observed in vitro following isolation and following transplantation contribute significantly to islet graft loss. Strategies to reduce apoptosis of islet tissue prior to and posttransplantation may improve graft survival and function and reduce the amount of tissue necessary to achieve insulin independence. The expression of cytoprotective proteins is one such strategy that may prolong islet survival. In this light, heme-oxygenase 1 (HO-1) upregulation has been studied in both allo- and xenotransplantation models. In this study, the effect of HO-1 on apoptosis in neonatal porcine islet-like cell clusters (NPICC) was assessed. In in vitro assessments of NPICC apoptosis, NPICC showed a high sensitivity to apoptotic stimulation using a combination of TNF-alpha and cycloheximide. Stimulation with TNF-alpha alone was sufficient to induce reproducible apoptotic responses as demonstrated by caspase-3,-7 activation and subdiploid DNA analysis. Dose-dependent, high-level HO-1 protein expression was achieved following culture of NPICC in medium containing either cobalt protoporphyrin (CoPP) or cobalt mesoporphyrin (CoMP). CoPP treatment resulted in the reduction of caspase-3,-7 enzyme activity following TNF-alpha stimulation. However, such an effect was not associated with a reduction in the levels of cell death. Indeed, the inhibition of caspase enzyme activity resulted in decreased PARP-1 cleavage, which may lead to heightened levels of necrosis in treated NPICC cultures, possibly explaining the observed commitment of NPICC to the death pathway.
Bosio
Erika
E
CORIT (Consorzio per la Ricerca sul Trapianto d'Organi), Padua, Italy. erika.bosio@unipd.it
Seveso
Michela
M
Dedja
Arben
A
Luca
Giovanni
G
Calvitti
Mario
M
Calafiore
Riccardo
R
Rigotti
Paolo
P
Busetto
Roberto
R
Ancona
Ermanno
E
Cozzi
Emanuele
E
D000818:Animals; D000831:Animals, Newborn; D053148:Caspase 3 / Q000378:metabolism*; D053179:Caspase 7 / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D009842:Oligopeptides / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011524:Protoporphyrins / Q000378:metabolism / Q000494:pharmacology*; D034421:Sus scrofa; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology
D015853:Cysteine Proteinase Inhibitors; D009842:Oligopeptides; D011500:Protein Synthesis Inhibitors; D011524:Protoporphyrins; D014409:Tumor Necrosis Factor-alpha; C099158:acetyl-aspartyl-glutamyl-valyl-aspartal; C007095:cobaltiprotoporphyrin; D003513:Cycloheximide; D051547:Heme Oxygenase-1; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D053179:Caspase 7