Ets1 and Ets2 are required for endothelial cell survival during embryonic angiogenesis

Abstract

The ras/Raf/Mek/Erk pathway plays a central role in coordinating endothelial cell activities during angiogenesis. Transcription factors Ets1 and Ets2 are targets of ras/Erk signaling pathways that have been implicated in endothelial cell function in vitro, but their precise role in vascular formation and function in vivo remains ill-defined. In this work, mutation of both Ets1 and Ets2 resulted in embryonic lethality at midgestation, with striking defects in vascular branching having been observed. The action of these factors was endothelial cell autonomous as demonstrated using Cre/loxP technology. Analysis of Ets1/Ets2 target genes in isolated embryonic endothelial cells demonstrated down-regulation of Mmp9, Bcl-X L , and cIAP2 in double mutants versus controls, and chromatin immunoprecipitation revealed that both Ets1 and Ets2 were loaded at target promoters. Consistent with these observations, endothelial cell apoptosis was significantly increased both in vivo and in vitro when both Ets1 and Ets2 were mutated. These results establish essential and overlapping functions for Ets1 and Ets2 in coordinating endothelial cell functions with survival during embryonic angiogenesis. (Blood. 2009;114:1123-1130) IntroductionAngiogenesis, the biologic process by which endothelial cells (ECs) form new blood vessels from an existing vascular network, is a critical process in normal vertebrate embryonic development, as well as in processes like wound healing and inflammation in adults. Angiogenesis is also an essential element in many pathologic conditions, including cancer. 1,2 Angiogenesis is regulated by a balance of both positive and negative signaling events mediated by growth factors and their receptors as well as by cell adhesion to the extracellular matrix. [1][2][3][4] These complex signaling and cell adhesion interactions alter the growth, migration, survival, and differentiation of ECs through modulation of the intracellular signaling pathways that control these processes. [1][2][3][4][5] Among these pathways, the ras/Raf/Mek/Erk pathway has been proposed to play a central role in coordinating these cellular activities during development and tumor angiogenesis. For example, gene knockouts of B-raf and Mek-1 point to their role in placental vascular formation during extraembryonic development, although their action in embryonic development is redundant. 6,7 Expression of dominant-negative Raf in the tumor vasculature in a transplantation model increases EC apoptosis and decreases tumor growth, 8 and sustained Erk activity is critical for EC migration and angiogenesis in the chick chorioallantoic membrane assay. 9 In cell culture studies, Erk signaling has been implicated in EC survival. [10][11][12] ECs are especially sensitive to apoptotic signals during angiogenesis, and the sustained activation of Erk signaling by the combination of growth factor receptors and integrin adhesion may be important in preventing cell death during this process. 9,10 The downstream targets of Erks that mediate these effects on ECs re...

Cdk5 controls lymphatic vessel development and function by phosphorylation of Foxc2

“…4), Ets transcription factors Ets1 and Ets2 (ref. 30). The transcription factors Ets1, Ets2 and Foxc2 are regulated by phosphorylation at serine/threonine residues 30,31 and therefore might be of special interest as potential Cdk5 targets.…”

“…30). The transcription factors Ets1, Ets2 and Foxc2 are regulated by phosphorylation at serine/threonine residues 30,31 and therefore might be of special interest as potential Cdk5 targets. However, we did not find obvious changes in expression of Foxc2, Prox1, Ets1 and Ets2, podoplanin or VEGFR3 (Supplementary Fig.…”

Differential expression of ETS family members in prostate cancer tissues and androgen-sensitive and insensitive prostate cancer cell lines

“…Although, the dNA-binding properties of ETS proteins are similar, different ETS proteins may exhibit preference for distinct flanking sequences in regulatory gene regions that could facilitate specificity and explain their unique biological functions (13). Redundant occupancy of ETS family members at proximal regulatory gene regions as well as overlapping functions have already been reported (13,14). The specificity and degree of transactivation for given target genes could result from dynamic binding equilibrium as well as from ternary complex formation of different ETS members with other transcription factors (15).…”

“…Nonetheless, binding preferences for distinct flanking sequences could facilitate specificity of ETS-factor binding and help to explain unique biological functions of different ETS proteins (13). Furthermore, redundant occupancy of ETS family members at proximal regulatory gene regions and overlapping functions for ETS factors have been reported (13,14 …”

The Role of the Transcription Factor Ets1 in Melanocyte Development

“…Murine thymocytes and T cells derived from Ets1 null mutant mice display higher apoptotic rates compared to those derived from wild type mice (Muthusamy et al, 1995 is caused by impaired angiogenesis as a result of decreased endothelial cell survival (Wei et al, 2009).…”