Diabetologie und Stoffwechsel 2007; 2 - V37
DOI: 10.1055/s-2007-982132

Norepinephrine mediates differential activation of NF-κB and subsequent proatherogenic gene expression

Z Djuric 1, M Huber 1, K Laine 1, PM Humpert 1, PP Nawroth 1, A Bierhaus 1
  • 1Universitätsklinikum Heidelberg, Innere Medizin I, Heidelberg, Germany

Background: Diabetes mellitus places considerable psychologic stress on the affected individuals. Psychosocial factors are associated with the development and progress of cardiovascular disease, but the pathological mechanisms are yet not clear. In previous work, we have identified norepinephrine (NE)- mediated activation of the proinflammatory transcription factor NF-κB in mononuclear cells as a pathway that converts psychosocial stress into cellular activation. Since this action requires a cooperated action of both α and β adrenergic receptors, we hypothesized that a differential activation of NFκB subunits might underlie the catecholamine-dependent expression of different proatherogenic genes.

Methods: In vitro studies: THP-1 cells were induced with physiologic concentrations of NE (10 nM) in the absence or presence of specific pathway inhibitors, before the extend of NF-κB activation, the composition of the NF-κB heterodimers, activation of pathway specific kinases and subsequent expression of proatherogenic NF-κB regulated target genes such as tissue factor (TF), endothelin-1 (ET-1) and ICAM-1 was studied using Chromatin Immunoprecipitation, Western Blots, and RT-PCR. Animal experiments: ApoE-/- mice were subjected to 1h restrain stress followed by 4h recovery and additional 1h restrain, in the presence and absence of adrenergic receptor antagonists. Serum-NE was determined by RIA. NFκB binding activity and nuclear translocation was confirmed in EMSA and Western Blots, before immunohistochemistry on aortic section for CD18, NFκB-p50, p65 and cRel and TF, ET-1 and ICAM-1 expression and fibrin formation was performed.

Results: NE increased binding activity to the NF-κB binding site in the TF, ET-1 and ICAM-1 promoters and subsequent synthesis of TF, ET-1 and ICAM-1 mRNA. NF-κB bound to TF promoter mainly consisted of cRel/p65 heterodimers; NFκB-p50, p65 and Crel were binding to ICAM-1 promoter, while NFκB p50 and p65 were bound to ET-1 promoter. NFκB-p50 translocation was mediated by α1 adrenergic receptor, Gi/0 protein and PKC. NFκB-p65 translocation was mediated by α1/β1/β2-receptors, Gi/o/Gs proteins, RAS, RAF and p38 MAPK, while NFκB-Crel translocation was mediated by α1/β1/β2-receptors, Gi/o/Gs proteins, RAS, RAF PI3/Akt p42/44 MAPK. Restrain stress induced a significant increase in serum NE concentration and NFκB binding activity in total blood which was inhibited by α1, β1 and β2 antagonists. Immunohistochemistry confirmed an increased nuclear translocation of all three NFκB subunits as well as increased expression of TF, ET-1 and ICAM-1 which could be specifically reduced by adrenergic antagonists.

Conclusion: Stimulation with physiologic concentrations of norepinephrine induces differential activation of NF-κB subunits, which in turn results in expression of proatherogenic gene products in mononuclear cells. This mechanism might contribute to the progression of vascular complications in patients with diabetes.