Synergistic Action of Flt3 and gp130 Signalings in Human Hematopoiesis

Abstract

We recently showed that c-kit signal synergizes with glycoprotein (gp)130 signal mediated by a complex of interleukin (IL)-6 and soluble IL-6 receptor (IL-6/sIL-6R) to stimulate the expansion of human primitive hematopoietic progenitor cells and erythropoietin-independent erythropoiesis. In the present study, we examined the effect of a ligand for Flt3 (FL), whose receptor tyrosine kinase is closely related to c-kit, in combination with IL-6/sIL-6R on human hematopoiesis in vitro. In serum-containing methylcellulose clonal culture of cord blood CD34+ cells, whereas FL alone stimulated only granulocyte-macrophage (GM) colony formation, erythroid bursts and mixed colonies in addition to GM colonies were induced by FL with IL-6/sIL-6R, but not IL-6/sIL-6R alone. In suspension culture, CD34+ cells generated a small number of myeloid cells in the presence of FL or IL-6/sIL-6R alone. However, the addition of IL-6/sIL-6R to the culture with FL induced the generation of a significant number of erythroid cells and megakaryocytes in addition to myeloid cells. The combination of FL and IL-6/sIL-6R also induced a remarkable expansion of GM colony- and erythroid burst-forming cells and multipotential progenitors, although FL or IL-6/sIL-6R alone induced the generation of only a small number of progenitors for GM colonies. The synergistic effects of FL and IL-6/sIL-6R were confirmed in serum-free clonal and suspension cultures. In addition, the addition of anti-human gp130 monoclonal antibodies abrogated the synergistic action. These results indicate that Flt3 signal, as well as c-kit signal, synergizes with gp130 signal to stimulate human myelopoiesis, erythropoiesis and megakaryopoiesis, and the expansion of primitive multipotential hematopoietic progenitor cells.

Multilevel Regulation of IL‐6R by IL‐6–sIL‐6R Fusion Protein According to the Primitiveness of Peripheral Blood‐Derived CD133+Cells

“…This inhibition must be time-limited because of the short half-life of SOCS proteins [10]. gp130 activation is an important signal for expansion of hematopoietic stem/progenitor cells [1][2][3][4][5][6][7][8], and the new gp130 ϩ mIL-6R ϩ cells can now respond directly to an IL-6 stimulation. sIL-6R resulting from ADAM protease activation stimulates cells lacking mIL-6R by trans-signaling process.…”

“…Over the last few years, numerous studies have suggested that the stimulation of glycoprotein 130 (gp130) is required for maintenance of hematopoietic stem cells (HSCs) [1][2][3][4][5][6][7][8]. This signaling receptor is activated by the cytokines belonging to the family of interleukin-6 (IL-6), including IL-6, IL-11, leukemia inhibitory factor (LIF), oncostatin-M (OSM), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), and cardiotrophin-1-like cytokine (CIC).…”

Concanavalin A simultaneously primes liver hematopoietic and epithelial progenitor cells for parallel expansion during liver regeneration after partial hepatectomy in mice

“…In any event, the parallel expansion of LHPC and LEPC is likely attributable to sharing of cytokine and growth factors/receptors between the two systems. [15][16][17][18][19][20][21][22][23][24][25][26] Examples include c-kit, 7,15,16,18 gp130, 17,60,61 FLT-3, 16,21,61,62 and met 20,63 ; stem cell factor, 15 IL-6, 45 leukemia inhibitory factor (LIF), 64 Flt3L, and HGF. 65 The combination of Con A and PH most effectively elicits LHPC and LEPC expansion in this model and illustrates the role of IL-6.…”

Low‐dose doxorubicin‐induced necrosis in Jurkat cells and its acceleration and conversion to apoptosis by antioxidants

“…Clonal cell culture for doxorubicin-treated cells. Methylcellulose cell culture was carried out in a 35-mm suspension culture dish (Nalge Nunc, Rochester, NY, USA) using Methocult H4230 (Stem Cell Technologies, Vancouver, Canada; Ebihara et al, 1997). Aliquots of rapidly growing or doxorubicin-treated cell cultures were further incubated under the same conditions except for the presence or absence of antioxidants.…”