title: Single Targeted Exon Mutation Creates a True Congenic Mouse for Competitive Hematopoietic Stem Cell Transplantation: The C57BL/6-CD45.1(STEM) Mouse.
abstract: Defining the molecular regulators of hematopoietic stem and progenitor cells (HSPCs) requires in vivo functional analyses. Competitive bone marrow transplants (BMTs) compare control and test HSPCs to demonstrate the functional role of a genetic change or chemical perturbation. Competitive BMT is enabled by antibodies that specifically recognize hematopoietic cells from congenic mouse strains due to variants of the cell surface protein CD45, designated CD45.1 and CD45.2. The current congenic competitor strain, B6.SJL-Ptprc(a) Pepc(b)/BoyJ (CD45.1), has a substantial inherent disadvantage in competition against the C57BL/6 (CD45.2) strain, confounding experimental interpretation. Despite backcrossing, the congenic interval over which the B6.SJL-Ptprc(a) Pepc(b)/BoyJ strain differs is almost 40 Mb encoding ∼300 genes. Here, we demonstrate that a single amino acid change determines the CD45.1 epitope. Further, we report on the single targeted exon mutant (STEM) mouse strain, CD45.1(STEM), which is functionally equivalent to CD45.2 cells in competitive BMT. This strain will permit the precise definition of functional roles for candidate genes using in vivo HSPC assays.
authors.affiliation: Center for Regenerative Medicine and Cancer Center, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA. Electronic address: fmercier@mgh.harvard.edu.
authors.forename: Francois E
authors.initials: FE
authors.lastname: Mercier
authors.affiliation: Center for Regenerative Medicine and Cancer Center, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA.
authors.forename: David B
authors.initials: DB
authors.lastname: Sykes
authors.affiliation: Center for Regenerative Medicine and Cancer Center, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA. Electronic address: dscadden@mgh.harvard.edu.
authors.forename: David T
authors.initials: DT
authors.lastname: Scadden
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000939:Epitopes / Q000235:genetics* / Q000276:immunology; D005091:Exons; D015870:Gene Expression; D018390:Gene Targeting; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D017493:Leukocyte Common Antigens / Q000235:genetics* / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology
chemical_list: D000939:Epitopes; D020033:Protein Isoforms; D017493:Leukocyte Common Antigens; C516770:Ptprc protein, mouse