The transcription factor Erg regulates expression of histone deacetylase 6 and multiple pathways involved in endothelial cell migration and angiogenesis

Abstract

The endothelial ETS transcription factor Erg plays an important role in homeostasis and angiogenesis by regulating many endothelial functions including survival and junction stability. Here we show that Erg regulates endothelial cell (EC) migration. Transcriptome profiling of Ergdeficient ECs identified ϳ 80 genes involved in cell migration as candidate Erg targets, including many regulators of RhoGTPases. Inhibition of Erg expression in HUVECs resulted in decreased migration in vitro, while Erg overexpression using adenovirus caused increased migration. Live-cell imaging of Erg-deficient HUVECs showed a reduction in lamellipodia, in line with decreased motility. Both actin and tubulin cytoskeletons were disrupted in Erg-deficient ECs, with a dramatic increase in tubulin acetylation. Among the most significant microarray hits was the cytosolic histone deacetylase 6 (HDAC6), a regulator of cell migration. Chromatin immunoprecipitation (ChIP) and transactivation studies demonstrated that Erg regulates HDAC6 expres- IntroductionAngiogenesis is a tightly controlled process that involves a cascade of events. A breakthrough in understanding the cellular and molecular mechanisms underlying angiogenesis has been the identification of highly motile, polarized endothelial cells (ECs), named tip cells, which lead the growth of the developing sprout. 1 Dynamic reorganization of the cytoskeleton in tip cells supports the projection of lamellipodia and filopodia, which allow the cell to sense the microenvironment for migration cues and guide the sprouting vessel toward an angiogenic stimulus. The functional cross-talk between the actin and tubulin cytoskeletal systems is essential for cell motility. 2 Several families of intracellular regulators control these pathways. Among the most studied are the small GTPases of the Rho family, with Rac as the main regulator of lamellipodia and CDC42 as the regulator of filopodia; both of these GTPases have been shown to be involved in angiogenesis. 3 The class II histone deacetylase 6 (HDAC6), a known regulator of cell motility, 4 has been recently shown to be involved in EC migration and to support angiogenesis. 5 HDAC6 is expressed in many cells (including ECs) and localizes predominantly to the cytoplasm, binding to microtubules and deacetylating several cytosolic proteins, including ␣-tubulin 4,6 and cortactin. 7 Acetylation of tubulin, characteristic of stabilized microtubules, is thought to contribute to regulating microtubule dynamics, 8 while acetylation of cortactin is thought to modulate actin dynamics by regulating the interaction of cortactin with F-actin. 7 HDAC6 modulation of both cytoskeletons mediates its role in regulating endothelial migration, cytoskeletal dynamics, and angiogenesis. 4,8 We have been interested in the transcriptional regulation of endothelial gene expression and angiogenesis, and have focused on the ETS transcription factor Erg (ETS-related gene). Erg is the most abundantly expressed ETS factor in resting ECs and its expression, although not uniquely ...

Dynamic regulation of VEGF-inducible genes by an ERK-ERG-p300 transcriptional network

“…Knockdown of ERG resulted in the downregulation of 202 genes, including CLDN5, RASIP1 and ARHGAP28 in serumstarved cells (Fig. S4A), consistent with previous studies (Birdsey et al, 2012;Yuan et al, 2012), and the upregulation of 68 genes. Gene ontology (GO) analysis revealed that the most frequent functional categories altered following loss of ERG were: response to wounding, inflammation, cell migration, cell motility and cell adhesion (Fig.…”

“…Crucially, mutation of S215 to alanine, an amino acid refractory to phosphorylation (a so-called 'phospho mutant'), abolishes ERG function in prostate cancer cells (Selvaraj et al, 2015). Although several studies have implicated ERG as a mediator of EC survival, proliferation, motility and vascular integrity (Birdsey et al, 2008(Birdsey et al, , 2012(Birdsey et al, , 2015Liu and Patient, 2008;Yuan et al, 2011), whether ERG acts as a hub, integrating signals downstream of VEGF to control these diverse EC behaviors is not known.…”

Expression of ERG, an Ets family transcription factor, identifies ERG-rearranged Ewing sarcoma

“…16,17 It is also constitutively expressed in normal endothelial cells and regulates angiogenesis and endothelial apoptosis. [18][19][20] Several studies have shown anti-ERG antibody useful for prostate carcinoma, metastatic and primary, and prostatic intraepithelial neoplasias. [10][11][12]21,22 The detection of ERG is highly correlated with both ERG rearrangement by fluorescence in-situ hybridization and with ERG mRNA overexpression.…”

IL-25 induces airways angiogenesis and expression of multiple angiogenic factors in a murine asthma model

“…vWF is a common marker for evaluating angiogenesis in vivo and ex vivo [12], while ERG is a member of the ETS (erythroblast transformation-specific) family of transcription factors which is selectively expressed by endothelial cells, specific haematopoetic cells and pre-cartilage cells. It has been shown that ERG plays an important role in blood vessel homeostasis and angiogenesis by regulating a variety of endothelial cellular functions including survival, junctional stability and migration [26]. Physiologically, airways blood vessel homeostasis likely reflects a balance between the production of endogenous angiogenic activators and inhibitors.…”