title: Growth promotion of genetically modified hematopoietic progenitors using an antibody/c-Mpl chimera.
abstract: Thrombopoietin is a potent cytokine that exerts proliferation of hematopoietic stem cells (HSCs) through its cognate receptor, c-Mpl. Therefore, mimicry of c-Mpl signaling by a receptor recognizing an artificial ligand would be attractive to attain specific expansion of genetically modified HSCs. Here we propose a system enabling selective expansion of genetically modified cells using an antibody/receptor chimera that can be activated by a specific antigen. We constructed an antibody/c-Mpl chimera, in which single-chain Fv (ScFv) of an anti-fluorescein antibody was tethered to the extracellular D2 domain of the erythropoietin receptor and transmembrane/cytoplasmic domains of c-Mpl. When the chimera was expressed in interleukin (IL)-3-dependent pro-B cell line Ba/F3, genetically modified cells were selectively expanded in the presence of fluorescein-conjugated BSA (BSA-FL) as a specific antigen. Furthermore, highly purified mouse HSCs transduced with the retrovirus carrying antibody/c-Mpl chimera gene proliferated in vitro in response to BSA-FL, and the cells retained in vivo long-term repopulating abilities. These results demonstrate that the antibody/c-Mpl chimera is capable of signal transduction that mimics wild-type c-Mpl signaling.
authors.affiliation: Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. kawahara@bio.t.u-tokyo.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kawahara
authors.forename: Jianhong
authors.initials: J
authors.lastname: Chen
authors.forename: Takahiro
authors.initials: T
authors.lastname: Sogo
authors.forename: Jinying
authors.initials: J
authors.lastname: Teng
authors.forename: Makoto
authors.initials: M
authors.lastname: Otsu
authors.forename: Masafumi
authors.initials: M
authors.lastname: Onodera
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Nakauchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueda
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Nagamune
mesh_terms: D000818:Animals; D000906:Antibodies / Q000378:metabolism; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019793:Fluorescein; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007377:Interleukin-3 / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D017467:Receptors, Erythropoietin / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D053628:Receptors, Thrombopoietin / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D057127:Single-Chain Antibodies / Q000378:metabolism*
chemical_list: D000906:Antibodies; D007377:Interleukin-3; C481270:Mpl protein, mouse; D017467:Receptors, Erythropoietin; D053628:Receptors, Thrombopoietin; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; D019793:Fluorescein