TNF initiates E-selectin transcription in human endothelial cells through parallel TRAF-NF-kappa B and TRAF-RAC/CDC42-JNK-c-Jun/ATF2 pathways.

Abstract

TNF acts on the E-selectin gene promoter at three kappa B elements and at a variant cAMP-responsive element that binds ATF2/c-Jun. In human endothelial cells, TNF rapidly induces N-terminal domain phosphorylation of both c-Jun and ATF2. Transient overexpression of N-terminal truncated c-Jun or catalytically inactive Jun N-terminal kinase (JNK) 1 and 2 inhibits TNF-induced transcription of an E-selectin but not a kappa B promoter-reporter gene. Transient overexpression of the TRAF2 adaptor protein can activate NF-kappaB and endogenous JNK, whereas N-terminal truncated TRAF2 protein blocks TNF-induced NF-kappa B and JNK activation as well as E-selectin promoter-reporter gene transcription. Transient overexpression of RAC1 or CDC42, but not RAS, constitutively activates JNK and augments TNF-induced E-selectin transcription. Finally, transient overexpression of catalytically inactive JNK or truncated TRAF2 partially inhibits endogenous E-selectin protein expression in human endothelial cells. These data suggest that TNF activates parallel TRAF-NF-kappa B and TRAF-RAC/CDC42-JNK-c-Jun/ATF2 pathways to initiate E-selectin transcription.