Involvement of the early growth response protein 1 in vascular pathophysiology: an overview.

Hyperactivation of proliferative and growth promoting pathways underlies the progression of vessel remodeling, leading to vascular dysfunction. An upregulation of early growth response protein 1 (Egr-1), a zinc finger transcription factor has been observed in several models of vascular diseases. In the vasculature, Egr-1 expression can be induced by multiple hormonal, metabolic and external stimuli, such as growth factors, cytokines, reactive oxygen species, hyperglycaemia and stretch-induced stress. The structure of the Egr-1 promoter allows both its auto-regulation and its binding with several regulatory transcription cofactors like the serum response factor and the cAMP response element binding protein. Pharmacological and genetic studies have revealed the involvement of several signaling pathways that contribute to the expression of Egr-1. Among them, the mitogen-activated protein kinase pathway has emerged as a predominant signaling cascade that regulates Egr-1 transcription in response to various stimuli. Moreover, targeted deletion of Egr-1 by DNAzymes, antisense oligonucleotides or RNA interference has also helped in defining the importance of Egr-1 in the pathophysiology of vascular diseases. Neointimal formation and expression of genes directly linked with proinflammatory processes have been demonstrated to be enhanced by Egr-1 expression and activity. This review provides an overview on the signaling components implicated in Egr-1 expression and discusses its potential involvement in vascular pathophysiology.