Combined genomic and antisense analysis reveals that the transcription factor Erg is implicated in endothelial cell differentiation

It has recently been shown that the transcription factor Erg, an Ets family member, drives constitutive expression of the intercellular adhesion molec ule 2 (ICAM-2) in human umbilical vein endothelial cells (HUVECs) and that its expression is downregulated by the pleiotropic cytokine tumor necrosis factor alpha (TNF-alpha). To identify other Erg target genes and to define its function in the endothelium, a combined approach of antisense oligonucl eotides (GeneBloc) and differential gene expression was used. Treatment of HUVECs with Erg-specific GeneBloc for 24, 48, and 72 hours suppressed Erg m RNA and protein levels at all time points. Total RNA extracted from HUVECs treated with Erg-specific or control GeneBloc was analyzed for differences in gene expression using high-density, sequence-verified cDNA arrays contai ning 482 relevant genes. Inhibition of Erg expression resulted in decreased expression of ICAM-2, as predicted. Four more genes decreased in Erg-defic ient HUVECs were the extracellular matrix proteins SPARC and thrombospondin , the adhesive glycoprotein von Willebrand factor, and the small GTPase Rho A. Each of these molecules has been directly or indirectly linked to angiog enesis because of its role in vascular remodeling, adhesion, or shape chang e. Therefore, the role of Erg in vascular remodeling was tested in an in vi tro model, and the results showed that HUVECs treated with Erg GeneBloc had a decreased ability to form tubulelike structures when grown on Matrigel. These results suggest that Erg may be a mediator of the TNF-alpha effects o n angiogenesis in vivo. (Blood. 2001;98:3332-3339) (C) 2001 by The American Society of Hematology.