title: Targeted disruption of the activating transcription factor 4 gene results in severe fetal anemia in mice.
abstract: Activating transcription factor (ATF) 4 is a ubiquitous basic leucine-zipper transcription factor that is a member of the ATF/cyclic adenosine monophosphate responsive element-binding (CREB) protein family. To determine the in vivo function of ATF4, the ATF4 gene in murine embryonic stem cells was deleted and homozygous mutant mice were generated. ATF4 null fetuses were severely anemic because of an impairment in fetal-liver definitive hematopoiesis; the hematocrit in 15.5-day mutant fetuses was 0.15, whereas that in controls was 0.35. The fetal livers in homozygous ATF4 mutants were pale and hypoplastic. In vitro culture of fetal-liver cells showed fewer hematopoietic progenitors per embryo and a dramatic decrease in the size of progenitor colonies. Culture of primary murine embryonic fibroblasts showed a proliferative defect. These results suggest that ATF4 is critical, in a cell-autonomous manner, for normal cellular proliferation, especially for the high-level proliferation required during fetal-liver hematopoiesis.
authors.affiliation: Department of Biochemistry, University of Alabama at Birmingham, 720 20th St S, Birmingham, AL 35294, USA.
authors.forename: Howard C
authors.initials: HC
authors.lastname: Masuoka
authors.forename: Tim M
authors.initials: TM
authors.lastname: Townes
mesh_terms: D051701:Activating Transcription Factor 4; D000740:Anemia / Q000097:blood / Q000196:embryology* / Q000209:etiology*; D000818:Animals; D002455:Cell Division; D004906:Erythrocyte Count; D005312:Fetal Blood / Q000737:chemistry / Q000166:cytology; D005315:Fetal Diseases / Q000097:blood* / Q000235:genetics; D005347:Fibroblasts / Q000166:cytology; D006128:Growth; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000473:pathology; D008099:Liver / Q000737:chemistry / Q000196:embryology / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000502:physiology*
chemical_list: D014157:Transcription Factors; D051701:Activating Transcription Factor 4