Identification of immediate early response protein 2 as a regulator of angiogenesis through the modulation of endothelial cell motility and adhesion.

ABSTRACT

Human immediate early response 2 (IER2) has been characterized as a putative nuclear protein that functions as a transcription factor or transcriptional co­activator in the regulation of cellular responses, and may be involved in the regulation of tumor progression and metastasis. Data from our previous gene expression profile of the human microvascular endothelial cells during capillary morphogenesis showed a significant alteration of IER2 expression, suggesting that IER2 may participate in the regulation of the endothelial cell morphogenesis and angiogenesis. The aim of the present study was to investigate the role of IER2 in cell motility, cell­matrix adhesion and in vitro capillary­like structures formation of the human umbilical vein endothelium cells (HUVECs). IER2 was constitutively expressed in HUVECs, and lentiviral­mediated depletion of IER2 significantly reduced the cell motility, cell­matrix adhesion and capillary­like structures formation of HUVECs. Results also showed that depletion and overexpression of IER2 altered the actin cytoskeleton rearrangement in HUVECs. Furthermore, results from western blot analysis showed that the activity of the focal adhesion kinase (FAK) can be regulated by IER2. These results indicated that IER2 regulates endothelial cell motility, adhesion on collagen type I matrix and the capillary tube formation, as the result of the regulation of the actin cytoskeleton rearrangement presumably via a FAK­dependent mechanism.