NF kappa B signaling in posthypoxic endothelial cells: Relevance to E-selectin expression and neutrophil adhesion

Our previous studies have implicated the nuclear transcription factor kappa B (NF kappaB) in the regulation of adhesion molecule expression in endothel ial cells exposed to anoxia-reoxygenation (A/R) or a redox imbalance. The o bjectives of this study were (1) to define the kinetics of NF kappaB activa tion by examining I kappaB alpha degradation and the nuclear translocation of p65 in response to A/R or redox imbalance (induced by treatment of cells with diamide and buthionine sulfoximine) and (2) to determine whether the signal for I kappaB alpha degradation, nuclear translocation of p65, and E- selectin-mediated neutrophil adhesion is related to the activity of protein tyrosine kinase (PTK), protein tyrosine phosphatase (PTPase) and/or protei n kinase C (PKC). The results demonstrate that both AIR and redox imbalance led to I kappaB alpha degradation within 30 min and the concomitant appear ance of p65 in the nucleus, consistent with rapid cytosolic activation of N F kappaB and subsequent nuclear translocation of the activated p65 subunit, inhibition of PKC blocked I kappaB alpha degradation and p65 translocation in A/R-challenged, but not redox-altered, endothelial cells. However, both A/R- and redox-induced NF kappaB activation was blocked by inhibition of P TK. Similarly, AIR-induced E-selectin expression and neutrophil-endothelial cell adhesion were blocked by inhibition of PKC or PTK, while only PTK inh ibited the redox-induced adhesion response. Pretreatment of cells with N-ac etyl cysteine effectively blocked A/R- or redox-induced I kappaB degradatio n and significantly attenuated the respective neutrophil adhesion responses . Collectively, these findings indicate that AIR-induced E-selectin express ion and neutrophil-endothelial cell adhesion are mediated by both PKC and P TK, which signal rapid activation of NF kappaB. This A/R-induced NF kappaB signaling response appears to be mediated, at least in part, by intracellul ar redox imbalance. Copyright (C) 2001 S. Karger AG. Basel.