Diabetes-associated sustained activation of the transcription factor nuclear factor-κB

Activation of the transcription factor nuclear factor-kappaB (NF-kappaB) has been suggested to participate in chronic disorders, such as diabetes and its complications. In contrast to the short and transient activation of NF-kappaB in vitro, we observed a long-lasting sustained activation of NF-kappaB in the absence of decreased I kappaB alpha in mononuclear cells from patients with type 1 diabetes. This was associated with increased transcription of NF-kappa Bp65. A comparable increase in NF-kappa Bp65 antigen and mRNA was also observed in vascular endothelial cells of diabetic rats. As a mechanism, we propose that binding of ligands such as advanced glycosylation end products (AGEs), members of the S100 family, or amyloid-beta peptide (A beta) to the transmembrane receptor for AGE (RAGE) results in protein synthesis-dependent sustained activation of NF-kappaB both in vitro and in vivo. Infusion of AGE-albumin into mice bearing a P-globin reporter transgene under control of NF-kappaB also resulted in prolonged expression of the reporter transgene. In vitro studies showed that RAGE-expressing cells induced sustained translocation of NF-kappaB (p50/p65) from the cytoplasm into the nucleus for >1 week. Sustained NF-kappaB activation by ligands of RAGE was mediated by initial degradation of I kappaB proteins followed by new synthesis of NF-kappa Bp65 mRNA and protein in the presence of newly synthesized I kappaB alpha and I kappaB beta. These data demonstrate that ligands of RAGE can induce sustained activation of NF-kappaB as a result of increased levels of de novo synthesized NF-kappa Bp65 overriding endogenous negative feedback mechanisms and thus might contribute to the persistent NF-kappaB activation observed in hyperglycemia and possibly other chronic diseases.