title: The Notch1 transcriptional activation domain is required for development and reveals a novel role for Notch1 signaling in fetal hematopoietic stem cells.
abstract: Notch1 is required to generate the earliest embryonic hematopoietic stem cells (HSCs); however since Notch-deficient embryos die early in gestation, additional functions for Notch in embryonic HSC biology have not been described. We used two complementary genetic models to address this important biological question. Unlike Notch1-deficient mice, mice lacking the conserved Notch1 transcriptional activation domain (TAD) show attenuated Notch1 function in vivo and survive until late gestation, succumbing to multiple cardiac abnormalities. Notch1 TAD-deficient HSCs emerge and successfully migrate to the fetal liver but are decreased in frequency by embryonic day 14.5. In addition, TAD-deficient fetal liver HSCs fail to compete with wild-type HSCs in bone marrow transplant experiments. This phenotype is independently recapitulated by conditional knockout of Rbpj, a core Notch pathway component. In vitro analysis of Notch1 TAD-deficient cells shows that the Notch1 TAD is important to properly assemble the Notch1/Rbpj/Maml trimolecular transcription complex. Together, these studies reveal an essential role for the Notch1 TAD in fetal development and identify important cell-autonomous functions for Notch1 signaling in fetal HSC homeostasis.
authors.affiliation: Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA;
authors.forename: Dawson M
authors.initials: DM
authors.lastname: Gerhardt
authors.forename: Kostandin V
authors.initials: KV
authors.lastname: Pajcini
authors.forename: Teresa
authors.initials: T
authors.lastname: D'altri
authors.forename: Lili
authors.initials: L
authors.lastname: Tu
authors.forename: Rajan
authors.initials: R
authors.lastname: Jain
authors.forename: Lanwei
authors.initials: L
authors.lastname: Xu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Chen
authors.forename: Stacey
authors.initials: S
authors.lastname: Rentschler
authors.forename: Olga
authors.initials: O
authors.lastname: Shestova
authors.forename: Gerald B
authors.initials: GB
authors.lastname: Wertheim
authors.forename: John W
authors.initials: JW
authors.lastname: Tobias
authors.forename: Michael
authors.initials: M
authors.lastname: Kluk
authors.forename: Antony W
authors.initials: AW
authors.lastname: Wood
authors.forename: Jon C
authors.initials: JC
authors.lastname: Aster
authors.forename: Phyllis A
authors.initials: PA
authors.lastname: Gimotty
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Epstein
authors.forename: Nancy
authors.initials: N
authors.lastname: Speck
authors.forename: Anna
authors.initials: A
authors.lastname: Bigas
authors.forename: Warren S
authors.initials: WS
authors.lastname: Pear
mesh_terms: D000818:Animals; D002460:Cell Line; D053686:Fetal Stem Cells; D018507:Gene Expression Regulation, Developmental; D055879:Gene Knock-In Techniques; D055786:Gene Knockout Techniques; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000502:physiology*; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009154:Mutation; D017434:Protein Structure, Tertiary / Q000235:genetics; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D016019:Survival Analysis
chemical_list: D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; C497571:Rbpj protein, mouse; D051881:Receptor, Notch1
keywords: Notch; hematopoietic stem cell; transcriptional activation domain