title: Conditional deletion of STAT5 in adult mouse hematopoietic stem cells causes loss of quiescence and permits efficient nonablative stem cell replacement.
abstract: Currently, there is a major need in hematopoietic stem cell (HSC) transplantation to develop reduced-intensity regimens that do not cause DNA damage and associated toxicities and that allow a wider range of patients to receive therapy. Cytokine receptor signals through c-Kit and c-Mpl can modulate HSC quiescence and engraftment, but the intracellular signals and transcription factors that mediate these effects during transplantation have not been defined. Here we show that loss of one allele of signal transducer and activator of transcription 5 (STAT5) in nonablated adult mutant mice permitted engraftment with wild-type HSC. Conditional deletion of STAT5 using Mx1-Cre caused maximal reduction in STAT5 mRNA (> 97%) and rapidly decreased quiescence-associated c-Mpl downstream targets (Tie-2, p57), increased HSC cycling, and gradually reduced survival and depleted the long-term HSC pool. Host deletion of STAT5 was persistent and permitted efficient donor long-term HSC engraftment in primary and secondary hosts in the absence of ablative conditioning. Overall, these studies establish proof of principle for targeting of STAT5 as novel transplantation conditioning and demonstrate, for the first time, that STAT5, a mitogenic factor in most cell types, including hematopoietic progenitors, is a key transcriptional regulator that maintains quiescence of HSC during steady-state hematopoiesis.
authors.affiliation: Department of Medicine, Hematology-Oncology, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Zhengqi
authors.initials: Z
authors.lastname: Wang
authors.forename: Geqiang
authors.initials: G
authors.lastname: Li
authors.forename: William
authors.initials: W
authors.lastname: Tse
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Bunting
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D053687:Adult Stem Cells / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D049109:Cell Proliferation; D017353:Gene Deletion; D018628:Gene Dosage / Q000502:physiology; D006410:Hematopoiesis / Q000235:genetics; D019650:Hematopoietic Stem Cell Mobilization / Q000379:methods; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000502:physiology*; D007108:Immune Tolerance / Q000235:genetics; D017493:Leukocyte Common Antigens / Q000235:genetics / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010750:Phosphoproteins / Q000235:genetics; D050799:STAT5 Transcription Factor / Q000235:genetics*; D019172:Transplantation Conditioning
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C490894:Gab2 protein, mouse; D010750:Phosphoproteins; D050799:STAT5 Transcription Factor; D017493:Leukocyte Common Antigens