TY - JOUR T1 - Depletion of Intracellular GTP Results in Nuclear Factor-κB Activation and Intercellular Adhesion Molecule-1 Expression in Human Endothelial Cells JF - Molecular Pharmacology JO - Mol Pharmacol SP - 453 LP - 462 DO - 10.1124/mol.62.3.453 VL - 62 IS - 3 AU - G. Weigel AU - P. Bertalanffy AU - E. Wolner Y1 - 2002/09/01 UR - http://molpharm.aspetjournals.org/content/62/3/453.abstract N2 - The expression of the intercellular adhesion molecule 1 (ICAM-1) on the surface of endothelial cells plays an important role in immune-mediated processes. The induction by the proinflammatory cytokine interleukin (IL)-1β is regulated by nuclear transcription factor κB (NF-κB). We studied the effect of an inosine-5′-monophosphate dehydrogenase (IMPDH) inhibitor, mycophenolic acid (MPA), on constitutive and IL-1β–induced expression of ICAM-1 in human umbilical vein endothelial cells (HUVECs). Unexpectedly, pretreatment with MPA enhanced the constitutive expression and potentiated the induction of ICAM-1 by IL-1β, as detected by flow cytometry. Northern blot analysis revealed an increase in ICAM-1 mRNA levels in cells treated with MPA. This was associated with an increase in phosphorylation of IκB-α (an inhibitor of NF-κB), nuclear translocation of the NF-κB subunits p50 and p65 and their binding to DNA as detected by Western blotting, confocal microscopy, and electrophoretic mobility shift assay. The up-regulation of ICAM-1 by MPA was prevented by high doses (100 μM) of guanine or guanosine but not by physiological doses (0.1 μM), indicating that guanylates are involved in endothelial responses to IL-1β. Cultivation of HUVECs in the absence of guanine enhanced further ICAM-1 expression during IMPDH inhibition. These results demonstrate that cytokine-mediated endothelial ICAM-1 expression can be modulated by IMPDH inhibition. We believe this represents a novel interaction between endothelial guanylate metabolism, NF-κB activation, and adhesion molecule expression. ER -