Essential role of signal transducer and activator of transcription (Stat)5a but not Stat5b for Flt3-dependent signaling

Shuli Zhang, Seiji Fukuda, Younghee Lee, Giao Hangoc, Scott Cooper, Rosanne Spolski, Warren J. Leonard, Hal E. Broxmeyer

Research output: Contribution to journalArticle

169 Scopus citations


The receptor tyrosine kinase Flt3 plays an important role in proliferation and survival of hematopoietic stem and progenitor cells. Although some post-receptor signaling events of Flt3 have been characterized, the involvement of the Janus kinase/signal transducer and activator of transcription (Jak/Stat) pathway in Flt3 signaling has not been thoroughly evaluated. To this aim, we examined whether Flt3 activates the Jak/Stat pathway in Baf3/Flt3 cells, a line stably expressing human Flt3 receptor. Stat5a, but not Stats 1-4, 5b, or 6, was potently activated by Flt3 ligand (FL) stimulation. Interestingly, FL did not activate any Jaks. Activation of Stat5a required the kinase activity of Flt3. A selective role for Stat5a in the proliferative response of primary hematopoietic progenitor cells to FL was documented, as FL did not act on progenitors from marrows of Stat5a(-/-) mice, but did stimulate/costimulate proliferation of these cells from Stat5a(+/+), Stat5b(-/-), and Stat5b(+/+) mice. Thus, Stat5a is essential for at least certain effects of FL. Moreover, our data confirm that Stat5a and Stat5b are not redundant, but rather are at least partially distinctive in their function.

Original languageEnglish (US)
Pages (from-to)719-728
Number of pages10
JournalJournal of Experimental Medicine
Issue number5
StatePublished - Sep 4 2000


  • Flt3
  • Gene knockout
  • Hematopoiesis
  • Signal transducer and activator of transfection 5
  • Signal transduction

ASJC Scopus subject areas

  • Immunology

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