title: Regulatory elements of the EKLF gene that direct erythroid cell-specific expression during mammalian development.
abstract: Erythroid Krüppel-like factor (EKLF) plays an essential role in enabling beta-globin expression during erythroid ontogeny. It is first expressed in the extraembryonic mesoderm of the yolk sac within the morphologically unique cells that give rise to the blood islands, and then later within the hepatic primordia. The BMP4/Smad pathway plays a critical role in the induction of EKLF, and transient transfection analyses demonstrate that sequences located within less than 1 kb of its transcription initiation site are sufficient for high-level erythroid-specific transcription. We have used transgenic analyses to verify that 950 bp located adjacent to the EKLF start site of transcription is sufficient to generate lacZ expression within the blood islands as well as the fetal liver during embryonic development. Of particular importance are 3 regions, 2 of which overlap endogenous erythroid-specific DNase hypersensitive sites, and 1 of which includes the proximal promoter region. The onset of transgene expression mimics that of endogenous EKLF as it begins by day 7.5 (d7.5) to d8.0. In addition, it exhibits a strict hematopoietic specificity, localized only to these cells and not to the adjacent vasculature at all stages examined. Finally, expression is heterocellular, implying that although these elements are sufficient for tissue-specific expression, they do not shield against the position effects of adjacent chromatin. These analyses demonstrate that a surprisingly small DNA segment contains all the information needed to target a linked gene to the hematopoietic compartment at both early and later stages of development, and may be a useful cassette for this purpose.
authors.affiliation: Mount Sinai School of Medicine, Brookdale Department of Molecular, Cell, and Developmental Biology, Box 1020, One Gustave L. Levy Pl, New York, NY 10029, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Xue
authors.forename: Xiaoyong
authors.initials: X
authors.lastname: Chen
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Chang
authors.forename: James J
authors.initials: JJ
authors.lastname: Bieker
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics*; D003851:Deoxyribonucleases; D004912:Erythrocytes / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D006410:Hematopoiesis / Q000502:physiology*; D051741:Kruppel-Like Transcription Factors; D008099:Liver / Q000196:embryology; D008322:Mammals; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D019076:Transgenes / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D051741:Kruppel-Like Transcription Factors; D014157:Transcription Factors; C080774:erythroid Kruppel-like factor; D003851:Deoxyribonucleases