AICA-riboside induces apoptosis of pancreatic beta cells through stimulation of AMP-activated protein kinase.
OBJECTIVE
Prolonged exposure of beta cells to low glucose concentrations triggers their apoptosis and is known to activate AMP-activated protein kinase (AMPK) in beta cell lines. We examined whether prolonged activation of AMPK can trigger apoptosis in rodent beta cells.


METHODS
Primary beta cells were FACS-purified from rats, and from wild-type and AMPK(alpha2)-deficient mice. AMPK activation in beta cells was induced by the adenosine analog AICA-riboside and detected by immunoblotting using a phosphospecific antibody. Apoptosis of rodent beta cells was monitored by FACS analysis of beta cell DNA content, by direct counting of apoptotic cells using fluorescence microscopy, or by measurement of their caspase-3 activity.


RESULTS
Dose-dependent and time-dependent apoptosis of the cells, concommittant with an activation of caspase-3, were suppressed by the caspase inhibitors zVAD-fmk and zDEVD-fmk. Apoptosis induction by AICA-riboside was also prevented by adding the MAPK-inhibitor SB203580 which blocked the AICA-riboside-induced phosphorylation of AMPK. Beta cells isolated from AMPK-(alpha2)-deficient mice were resistant against AICA-riboside induced apoptosis.


CONCLUSIONS
Sustained activation of AMPK by AICA-riboside can trigger a caspase-dependent apoptosis of pancreatic beta cells.
Kefas
B A
BA
Diabetes Research Center, Free Brussels University-VUB, Laarbeeklaan 103, 1090 Brussels, Belgium.
Heimberg
H
H
Vaulont
S
S
Meisse
D
D
Hue
L
L
Pipeleers
D
D
Van de Casteele
M
M
D055372:AMP-Activated Protein Kinases; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D007515:Islets of Langerhans / Q000187:drug effects* / Q000502:physiology*; D051379:Mice; D009097:Multienzyme Complexes / Q000172:deficiency / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000378:metabolism*; D051381:Rats; D012263:Ribonucleosides / Q000494:pharmacology*
D009097:Multienzyme Complexes; D012263:Ribonucleosides; D000620:Aminoimidazole Carboxamide; C011651:acadesine; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases