Overexpression of the nuclear factor-κB subunit c-Rel protects against human islet cell death in vitro.
The transcription factor nuclear factor (NF)-κB is known to modulate rates of apoptosis and may therefore play a role in the increased β-cell death that occurs in type 1 and type 2 diabetes. The aim of the present investigation was to study the expression of NF-κB subunits in human islet cells and whether overexpression of the NF-κB subunit c-Rel affects islet cell survival. We detected expression of p65, Rel-B, p50, p105, p52, and the ribosomal protein S3 (rpS3) in human islet cells. Among these, only p65 and rpS3 were translocated from the cytosolic to the nuclear fraction in response to cytokines. Interestingly, rpS3 participated in p65 binding to the κB-element in gel shift analysis experiments. We observed cytoplasmic c-Rel expression in vivo in 6J mice, and signs of nuclear translocation in β-cells of infiltrated nonobese diabetic islets. Human islet cells were also dispersed by trypsin treatment and transduced with a c-Rel adenoviral vector. This resulted in increased expression of c-Rel and inhibitory factor κB, increased κB-binding activity, and augmented protein levels of Bcl-X(L,) c-IAP2, and heat shock protein 72. c-Rel expression in human islet cells protected against cytokine-induced caspase 3 activation and cell death. c-Rel protected also against streptozotocin- and H(2)O(2)-induced cell death, in both intact rat islets and human islet cells. We conclude that rpS3 participates in NF-κB signaling and that a genetic increase in the activity of the NF-κB subunit c-Rel results in protection against cell death in human islets.
Mokhtari
Dariush
D
Dept. of Medical Cell Biology, Uppsala Univ., Biomedicum, P.O. Box 571, S-751 23, Uppsala, Sweden.
Barbu
Andreea
A
Mehmeti
Ilir
I
Vercamer
Chantal
C
Welsh
Nils
N
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D015153:Blotting, Western; D016923:Cell Death / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D004396:Coloring Agents; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D015870:Gene Expression / Q000502:physiology; D005822:Genetic Vectors; D006801:Humans; D007515:Islets of Langerhans / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D018613:Microscopy, Confocal; D016328:NF-kappa B / Q000096:biosynthesis* / Q000502:physiology*; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D010477:Perfusion; D021122:Protein Subunits / Q000096:biosynthesis* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013778:Tetrazolium Salts; D013844:Thiazoles; D014161:Transduction, Genetic
D051017:Apoptosis Regulatory Proteins; D004396:Coloring Agents; D016328:NF-kappa B; D009687:Nuclear Proteins; D021122:Protein Subunits; D013778:Tetrazolium Salts; D013844:Thiazoles; C022616:thiazolyl blue