Selective activation of STAT5 unveils its role in stem cell self-renewal in normal and leukemic hematopoiesis.
Although the concept of a leukemic stem cell system has recently been well accepted, its nature and the underlying molecular mechanisms remain obscure. Constitutive activation of signal transducers and activators of transcription 3 (STAT3) and STAT5 is frequently detected in various hematopoietic tumors. To evaluate their role in normal and leukemic stem cells, we took advantage of constitutively active STAT mutants to activate STAT signaling selectively in hematopoietic stem cells (HSCs). Activation of STAT5 in CD34- c-Kit+ Sca-1+ lineage marker- (CD34- KSL) HSCs led to a drastic expansion of multipotential progenitors and promoted HSC self-renewal ex vivo. In sharp contrast, STAT3 was demonstrated to be dispensable for the HSC maintenance in vivo, and its activation facilitated lineage commitment of HSCs in vitro. In a mouse model of myeloproliferative disease (MPD), sustained STAT5 activation in CD34- KSL HSCs but not in CD34+ KSL multipotential progenitors induced fatal MPD, indicating that the capacity of STAT5 to promote self-renewal of hematopoietic stem cells is crucial to MPD development. Our findings collectively establish a specific role for STAT5 in self-renewal of normal as well as leukemic stem cells.
Laboratory of Stem Cell Therapy, Center for Experimental Medicine, Tokyo, Japan.
Yuko
Y
Kato
Atsushi
A
Iwama
Yuko
Y
Tadokoro
Kazuya
K
Shimoda
Mayu
M
Minoguchi
Shizuo
S
Akira
Minoru
M
Tanaka
Atsushi
A
Miyajima
Toshio
T
Kitamura
Hiromitsu
H
Nakauchi
D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D066298:In Vitro Techniques; D007942:Leukemia, Experimental / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008894:Milk Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009196:Myeloproliferative Disorders / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D008894:Milk Proteins; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators