Inhibition of cytokine-induced NF-kappaB activation by adenovirus-mediated expression of a NF-kappaB super-repressor prevents beta-cell apoptosis.
Cytokine-induced beta-cell death is an important event in the pathogenesis of type 1 diabetes. The transcription factor nuclear factor-kappaB (NF-kappaB) is activated by interleukin-1beta (IL-1beta), and its activity promotes the expression of several beta-cell genes, including pro- and anti-apoptotic genes. To elucidate the role of cytokine (IL-1beta + gamma-interferon [IFN-gamma])-induced expression of NF-kappaB in beta-cell apoptosis, rat beta-cells were infected with the recombinant adenovirus AdIkappaB((SA)2), which contained a nondegradable mutant form of inhibitory kappaB (IkappaB((SA)2), with S32A and S36A) that locks NF-kappaB in a cytosolic protein complex, preventing its nuclear action. Expression of IkappaB((SA)2) inhibited cytokine-stimulated nuclear translocation and DNA-binding of NF-kappaB. Cytokine-induced gene expression of several NF-kappaB targets, namely inducible nitric oxide synthase, Fas, and manganese superoxide dismutase, was prevented by AdIkappaB((SA)2), as established by reverse transcriptase-polymerase chain reaction, protein blot, and measurement of nitrite in the medium. Finally, beta-cell survival after IL-1beta + IFN-gamma treatment was significantly improved by IkappaB((SA)2) expression, mostly through inhibition of the apoptotic pathway. Based on these findings, we conclude that NF-kappaB activation, under in vitro conditions, has primarily a pro-apoptotic function in beta-cells.
Heimberg
H
H
Diabetes Research Center, Vrije Universiteit Brussel, Brussels, Belgium. hheimber@vub.vub.ac.be
Heremans
Y
Y
Jobin
C
C
Leemans
R
R
Cardozo
A K
AK
Darville
M
M
Eizirik
D L
DL
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D015870:Gene Expression; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D020672:I-kappa B Proteins / Q000235:genetics / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D007375:Interleukin-1 / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000502:physiology*; D008297:Male; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D051381:Rats; D017208:Rats, Wistar
D020672:I-kappa B Proteins; D007375:Interleukin-1; D016328:NF-kappa B; D007371:Interferon-gamma