title: Phosphorylation of Runx1 at Ser249, Ser266, and Ser276 is dispensable for bone marrow hematopoiesis and thymocyte differentiation.
abstract: Runx1, one of three mammalian runt-domain transcription factor family proteins, is essential for definitive hematopoiesis. Based on transfection assays, phosphorylation of Runx1 at the three serine residues, Ser249, Ser266, and Ser276, was thought to be important for trans-activation activity of Runx1. By using "knock-in" gene targeting, we generated mouse strains expressing mutant Runx1 protein that harbored a combined serine-to-alanine substitution at either of two residues, Ser249/Ser266 or Ser249/Ser276. Either mutation resulted in a lack of major phosphorylated form of Runx1. However, while loss of definitive hematopoiesis and impaired thymocyte differentiation was observed following the loss of Runx1, these phenotypes were rescued in those mice lacking the major phosphorylated form of Runx1. These results not only challenge the predicted regulation of Runx1 activity by phosphorylation at these serine residues, but also reaffirm the effectiveness of "knock-in" mutagenesis as a powerful tool for addressing the physiological relevance of post-translation modifications.
authors.affiliation: Laboratory for Transcriptional Regulation, RIKEN Research Center for Allergy and Immunology, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Tachibana
authors.forename: Chieko
authors.initials: C
authors.lastname: Tezuka
authors.forename: Sawako
authors.initials: S
authors.lastname: Muroi
authors.forename: Sogo
authors.initials: S
authors.lastname: Nishimoto
authors.forename: Takuo
authors.initials: T
authors.lastname: Katsumoto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nakajima
authors.forename: Issay
authors.initials: I
authors.lastname: Kitabayashi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Taniuchi
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D050676:Core Binding Factor Alpha 2 Subunit / Q000737:chemistry / Q000378:metabolism; D006410:Hematopoiesis / Q000502:physiology*; D008214:Lymphocytes / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D012694:Serine / Q000737:chemistry / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism
chemical_list: D050676:Core Binding Factor Alpha 2 Subunit; C493726:Runx1 protein, mouse; D012694:Serine