Activation and Nuclear translocation of p65 NF-kappaB are sufficient for VCAM-1, but insufficient for ICAM-1, expression in TNF-stimulated primary smooth muscle cells: differential requirement for PARP-1 expression and interaction (B73)

Abstract

Abstract Although nuclear translocation of NF-κB and subsequent binding to promoters of ICAM-1 and VCAM-1 have been shown to be decisive for their expression, a number of discrepancies in the expression pattern of these adhesion molecules have been reported in cell culture systems and in disease settings including atherosclerosis, asthma, and auto-immune diseases. Here we show that while p65 NF-κB nuclear translocation in TNF-treated smooth muscle cells (SMC) was sufficient for the expression of VCAM-1, ICAM-1 expression required the expression of PARP-1. I-κBα phosphorylation and subsequent degradation were virtually identical in both TNF-treated wild type and PARP-1−/− SMC. VCAM-1 expression in TNF-treated PARP-1−/− SMC was confirmed to be NF-κB-dependent given that PDTC inhibited its expression. The expression of VCAM-1 and ICAM-1 were associated with a transient interaction between PARP-1 and p65 NF-κB when examined in the airway epithelial cell line A549. Such interaction was confirmed using fluorescence resonance energy transfer (FRET) assay. Protein acetylation activity, mediated by p300/CBP, was required for VCAM-1 and ICAM-1 expression in TNF-treated SMC, however, interaction of PARP-1 with p300 was not required for VCAM-1 expression. These findings indicate that p65 NF-κB translocation can be in some situations insufficient for some genes (e.g. ICAM-1) yet in the same time can induce the expression of others (e.g. VCAM-1), thus providing a new concept on the role of NF-κB in driving its target genes. Further, the data suggest a differential requirement for PARP-1 expression in inflammatory processes. Support: NIH-HL072889 and 1P20RR18766 to HB.