Nkx2–5 transactivates the Ets-related protein 71 gene and specifies an endothelial/endocardial fate in the developing embryo

Abstract

Recent studies support the existence of a common progenitor for the cardiac and endothelial cell lineages, but the underlying transcriptional networks responsible for specification of these cell fates remain unclear. Here we demonstrated that Ets-related protein 71 (Etsrp71), a newly discovered ETS family transcription factor, was a novel downstream target of the homeodomain protein, Nkx2-5. Using genetic mouse models and molecular biological techniques, we demonstrated that Nkx2-5 binds to an evolutionarily conserved Nkx2-5 response element in the Etsrp71 promoter and induces the Etsrp71 gene expression in vitro and in vivo. Etsrp71 was transiently expressed in the endocardium/endothelium of the developing embryo (E7.75-E9.5) and was extinguished during the latter stages of development. Using a gene disruption strategy, we found that Etsrp71 mutant embryos lacked endocardial/endothelial lineages and were nonviable. Moreover, using transgenic technologies and transcriptional and chromatin immunoprecipitation (ChIP) assays, we further established that Tie2 is a direct downstream target of Etsrp71. Collectively, our results uncover a novel functional role for Nkx2-5 and define a transcriptional network that specifies an endocardial/endothelial fate in the developing heart and embryo.cardiac progenitor cells ͉ endocardium ͉ Etsrp71 ͉ Tie2 ͉ cardiac development

Forkhead factor FoxO1 is essential for placental morphogenesis in the developing embryo

“…Also, coexpression of FoxO1 and VCAM1 genes was confirmed in endothelial progenitor cells using qRT-PCR analyses of RNA extracted from Tie2-GFP + cells (Fig. S7B) (17). At the same time, significant dysregulation of p21CIP, a known downstream target gene of FoxO1 (26), in FoxO1-null heart (Fig.…”

“…To gain insight into the role of FoxO1 in development, we mated FoxO1 heterozygous mice (6) and isolated FoxO1-WT, -heterozygous, and -null embryos from timed pregnant females at distinct developmental stages (17). Consistent with previously reported studies (6, 9, 11), FoxO1-null embryos were dead at E10.5, and multiple cardiovascular malformations, including looping defects, pericardial edema, and hemorrhage, were ap- parent at E9.5 (Fig.…”

“…1A and 2) was not associated with vascular/cardiovascular malformation. Indeed, early developing embryos deficient of the ER71 gene, a master regulator of the genesis of the cardiovascular system, do not manifest a misshapen allantois (17). On the basis of these data, we hypothesized that FoxO1 plays an essential role in placental development.…”

“…FoxO1 knockout mice were described previously (6). The staging and processing of embryos and genotyping using genomic DNA, extracted either from yolk sacs or embryo proper, were described previously (17). All mice were maintained in the animal facility at University of Texas Southwestern Medical Center according to the guidelines of the institutional animal care and use committee and the Animal Resource Center.…”

“…Histological and immunostaining analyses for α-endomucin and Ki67 were described previously (17). Immunostaining for activated caspase-3 (Cell Signaling; no.…”