Transcription regulation of TNF- -early response genes by poly(ADP-ribose) polymerase-1 in murine heart endothelial cells

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Abstract
Poly(ADP-ribose) polymerase-1 (PARP-1) has been involved in endothelial cell dysfunction associated with various pathophysiological conditions. The intrinsic mechanism of PARP-1-mediated endothelial cell dysfunction could be related to PARP-1 overactivation, NAD(+) consumption and ATP depletion. An alternative way could involve transcription regulation. By using high-density microarrays, we examined early tumor necrosis factor alpha (TNF-alpha)-stimulated gene expression profiles in PARP-1(+/+) and PARP-1(-/-) murine heart endothelial cells. TNF-alpha modulated a significant number of genes in both cell types. We have identified a set of genes whose expression in response to TNF-alpha is modulated by PARP-1, whereas the expression of others is PARP-1-independent. Up-regulation of several genes involved in the inflammatory response is hampered in the absence of PARP-1. Moreover, NF-kappaB-dependent transcriptional activation is partially inhibited in PARP-1(-/-) compared to PARP-1(+/+) cells. However, we found that PARP-1 might also silence transcription of several NF-kappaB target genes. Overall, our results show that PARP-1 is regulating the expression of genes by the endothelial cells both in a positive and a negative fashion, with the final effects depending on the gene. Individual studies of these genes are now necessary to clarify the intrinsic mechanism by which PARP-1 is controlling transcription and thereby finding out different therapeutic approaches involving PARP-1.