title: Etv2 is expressed in the yolk sac hematopoietic and endothelial progenitors and regulates Lmo2 gene expression.
abstract: During embryogenesis, the endothelial and the hematopoietic lineages first appear during gastrulation in the blood island of the yolk sac. We have previously reported that an Ets variant gene 2 (Etv2/ER71) mutant embryo lacks hematopoietic and endothelial lineages; however, the precise roles of Etv2 in yolk sac development remains unclear. In this study, we define the role of Etv2 in yolk sac blood island development using the Etv2 mutant and a novel Etv2-EYFP reporter transgenic line. Both the hematopoietic and the endothelial lineages are absent in the Etv2 mutant yolk sac. In the Etv2-EYFP transgenic mouse, the EYFP reporter is activated in the nascent mesoderm, expressed in the endothelial and blood progenitors, and in the Tie2(+), c-kit(+), and CD41(+) hematopoietic population. The hematopoietic activity in the E7.75 yolk sac was exclusively localized to the Etv2-EYFP(+) population. In the Etv2 mutant yolk sac, Tie2(+) cells are present but do not express hematopoietic or endothelial markers. In addition, these cells do not form hematopoietic colonies, indicating an essential role of Etv2 in the specification of the hematopoietic lineage. Forced overexpression of Etv2 during embryoid body differentiation induces the hematopoietic and the endothelial lineages, and transcriptional profiling in this context identifies Lmo2 as a downstream target. Using electrophoretic mobility shift assay, chromatin immunoprecipitation, transcriptional assays, and mutagenesis, we demonstrate that Etv2 binds to the Lmo2 enhancer and transactivates its expression. Collectively, our studies demonstrate that Etv2 is expressed during and required for yolk sac hematoendothelial development, and that Lmo2 is one of the downstream targets of Etv2.
authors.affiliation: Lillehei Heart-Institute, Department of Medicine, Medical School, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Naoko
authors.initials: N
authors.lastname: Koyano-Nakagawa
authors.forename: Junghun
authors.initials: J
authors.lastname: Kweon
authors.forename: Michelina
authors.initials: M
authors.lastname: Iacovino
authors.forename: Xiaozhong
authors.initials: X
authors.lastname: Shi
authors.forename: Tara L
authors.initials: TL
authors.lastname: Rasmussen
authors.forename: Luciene
authors.initials: L
authors.lastname: Borges
authors.forename: Katie M
authors.initials: KM
authors.lastname: Zirbes
authors.forename: Tongbin
authors.initials: T
authors.lastname: Li
authors.forename: Rita C R
authors.initials: RC
authors.lastname: Perlingeiro
authors.forename: Michael
authors.initials: M
authors.lastname: Kyba
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Garry
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D015870:Gene Expression; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D060588:LIM Domain Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D015017:Yolk Sac / Q000166:cytology / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C503994:ER71 protein, mouse; D060588:LIM Domain Proteins; C513188:Lmo2 protein, mouse; D014157:Transcription Factors