Inhibition of granulocyte colony-stimulating factor–mediated myeloid maturation by low level expression of the differentiation-defective class IV granulocyte colony-stimulating factor receptor isoform

Blood ◽  
2000 ◽  
Vol 95 (11) ◽  
pp. 3335-3340 ◽  
Author(s):  
Scott M. White ◽  
Mark H. Alarcon ◽  
David J. Tweardy

In acute myeloid leukemia (AML), granulocyte colony-stimulating factor receptor (G-CSFR) proliferative and maturational signaling pathways are uncoupled. Seven human G-CSFR mRNA isoforms exist, named class I through class VII. The 183-amino acid cytosolic domain of the class I isoform provides all signaling activities. The class IV isoform is “differentiation defective” because the carboxy-terminal 87 amino acids are replaced with 34 amino acids of novel sequence. In more than 50% of AML samples, the class IV/class I G-CSFR mRNA ratio is aberrantly elevated compared to normal CD34+ bone marrow cells. We hypothesized that the increased relative expression of class IV G-CSFR in AML uncouples proliferative and maturational G-CSFR signaling pathways. To test this, we transfected the G-CSF–responsive murine cell line 32Dcl3 with class IV G-CSFR cDNA. After 10 days of G-CSF stimulation, clones expressing class IV G-CSFR had greater percentages of myeloblasts and promyelocytes than controls (53% ± 13% versus 3% ± 2%). Differential counts over time demonstrated delayed G-CSF–driven maturation in 5 class IV-expressing clones, with 2 clones demonstrating a subpopulation that completely failed to differentiate. Heterologous class IV expression did not affect G-CSF–dependent proliferation. Class IV/murine G-CSFR mRNA ratios after 24 hours of G-CSF stimulation for 3 of the 5 clones (range, 0.090 to 0.245; mean, 0.152 ± 0.055) are within the range of class IV/class I mRNA ratios seen in patients with AML. This indicates that aberrantly increased relative class IV G-CSFR expression seen in AML can uncouple G-CSFR proliferative and maturational signaling pathways.

Blood ◽  
2000 ◽  
Vol 95 (11) ◽  
pp. 3335-3340 ◽  
Author(s):  
Scott M. White ◽  
Mark H. Alarcon ◽  
David J. Tweardy

Abstract In acute myeloid leukemia (AML), granulocyte colony-stimulating factor receptor (G-CSFR) proliferative and maturational signaling pathways are uncoupled. Seven human G-CSFR mRNA isoforms exist, named class I through class VII. The 183-amino acid cytosolic domain of the class I isoform provides all signaling activities. The class IV isoform is “differentiation defective” because the carboxy-terminal 87 amino acids are replaced with 34 amino acids of novel sequence. In more than 50% of AML samples, the class IV/class I G-CSFR mRNA ratio is aberrantly elevated compared to normal CD34+ bone marrow cells. We hypothesized that the increased relative expression of class IV G-CSFR in AML uncouples proliferative and maturational G-CSFR signaling pathways. To test this, we transfected the G-CSF–responsive murine cell line 32Dcl3 with class IV G-CSFR cDNA. After 10 days of G-CSF stimulation, clones expressing class IV G-CSFR had greater percentages of myeloblasts and promyelocytes than controls (53% ± 13% versus 3% ± 2%). Differential counts over time demonstrated delayed G-CSF–driven maturation in 5 class IV-expressing clones, with 2 clones demonstrating a subpopulation that completely failed to differentiate. Heterologous class IV expression did not affect G-CSF–dependent proliferation. Class IV/murine G-CSFR mRNA ratios after 24 hours of G-CSF stimulation for 3 of the 5 clones (range, 0.090 to 0.245; mean, 0.152 ± 0.055) are within the range of class IV/class I mRNA ratios seen in patients with AML. This indicates that aberrantly increased relative class IV G-CSFR expression seen in AML can uncouple G-CSFR proliferative and maturational signaling pathways.


2006 ◽  
Vol 26 (21) ◽  
pp. 8052-8060 ◽  
Author(s):  
Ewa Sicinska ◽  
Young-Mi Lee ◽  
Judith Gits ◽  
Hirokazu Shigematsu ◽  
Qunyan Yu ◽  
...  

ABSTRACT The proliferation of neutrophil granulocyte lineage is driven largely by granulocyte colony-stimulating factor (G-CSF) acting via the G-CSF receptors. In this study, we show that mice lacking cyclin D3, a component of the core cell cycle machinery, are refractory to stimulation by the G-CSF. Consequently, cyclin D3-null mice display deficient maturation of granulocytes in the bone marrow and have reduced levels of neutrophil granulocytes in their peripheral blood. The mutant mice are unable to mount a normal response to bacterial challenge and succumb to microbial infections. In contrast, the expansion of hematopoietic stem cells and lineage-committed myeloid progenitors proceeds relatively normally in mice lacking cyclin D3, revealing that the requirement for cyclin D3 function operates at later stages of neutrophil development. Importantly, we verified that this requirement is specific to cyclin D3, as mice lacking other G1 cyclins (D1, D2, E1, or E2) display normal granulocyte counts. Our analyses revealed that in the bone marrow cells of wild-type mice, activation of the G-CSF receptor leads to upregulation of cyclin D3. Collectively, these results demonstrate that cyclin D3 is an essential cell cycle recipient of G-CSF signaling, and they provide a molecular link of how G-CSF-dependent signaling triggers cell proliferation.


Blood ◽  
1990 ◽  
Vol 76 (10) ◽  
pp. 1956-1961 ◽  
Author(s):  
H Ema ◽  
T Suda ◽  
K Nagayoshi ◽  
Y Miura ◽  
CI Civin ◽  
...  

Abstract To study the relationship between hematopoietic factors and their responsive hematopoietic progenitors in the differentiation process, both purified factors and enriched progenitors are required. We isolated total CD34+ cells, CD34+,CD33+ cells, and CD34+,CD33- cells individually from normal human bone marrow cells by fluorescence- activated cell sorter (FACS), and examined the effects of granulocyte colony-stimulating factor (G-CSF), interleukin-3 (IL-3), and IL-5 on in vitro colony formation of these cells. CD34+,CD33+ cells formed granulocyte colonies in the presence of G-CSF. Both CD34+,CD33+ cells and CD34+,CD33- cells formed granulocyte/macrophage colonies in the presence of IL-3. Eosinophil (Eo) colonies were only formed by CD34+,CD33- cells in response to IL-3, but scarcely formed by CD34+ cells in the presence of IL-5. We performed the two-step cultures consisting of the primary liquid culture for 6 days and the secondary methylcellulose culture, and serially examined changes in phenotypes of ,he cells cultured in the primary culture. CD34-,CD33+ cells derived from CD34+,CD33+ cells by preincubation with G-CSF or IL-3 formed Eo colonies in the presence of IL-5 but not IL-3. CD34-,CD33+ cells derived from CD34+,CD33- cells by preincubation with IL-3 also formed Eo colonies by support of IL-5 as well as IL-3. Both CD34+ cells gradually lost the CD34 antigen by day 6 of incubation with G-CSF or IL- 3. Loss of this antigen was well-correlated with acquisition of susceptibility to IL-5. It was concluded that G-CSF supported the neutrophil differentiation of committed colony-forming cells, IL-3 supported that of both committed and multipotent colony-forming cells. G-CSF and IL-3 also supported the early stage of E. differentiation; IL- 5 supported the late stage of that.


Blood ◽  
1999 ◽  
Vol 93 (1) ◽  
pp. 113-124 ◽  
Author(s):  
Alister C. Ward ◽  
Mirjam H.A. Hermans ◽  
Louise Smith ◽  
Yvette M. van Aesch ◽  
Anita M. Schelen ◽  
...  

Abstract The granulocyte colony-stimulating factor receptor (G-CSF-R) activates multiple STAT proteins. Although the membrane-proximal cytoplasmic region of the G-CSF-R is necessary and sufficient for activation of STAT1 and STAT5, activation of STAT3 requires the membrane distal region that contains four tyrosines. Although one of these (Y704) has previously been shown to be involved in STAT3 activation from a truncated G-CSF-R derived from a patient with severe chronic neutropenia (SCN), this tyrosine is not required for STAT3 activation by the full-length G-CSF-R. To investigate possible alternative mechanisms of STAT3 activation, we generated a series of Ba/F3 cell transfectants expressing the wild-type G-CSF-R or mutant receptors that either completely lack tyrosines or retain just one of the four cytoplasmic tyrosines of the G-CSF-R. We show that, at saturating G-CSF concentrations, STAT3 activation from the full-length G-CSF-R is efficiently mediated by the C-terminal domain in a manner independent of receptor tyrosines. In contrast, at low G-CSF concentrations, Y704 and Y744 of the G-CSF-R play a major role in STAT3 activation. Both tyrosine-dependent and -independent mechanisms of STAT3 activation are sensitive to the Jak2 inhibitor AG-490, follow similar kinetics, and lead to transactivation of a STAT3 reporter construct, indicating functional equivalence. STAT3 activation is also impaired, particularly at nonsaturating G-CSF concentrations, in bone marrow cells from mice expressing a truncated G-CSF-R (gcsfr-▵715). These findings suggest that G-CSF–induced STAT3 activation during basal granulopoiesis (low G-CSF) and “emergency” granulopoiesis (high G-CSF) are differentially controlled. In addition, the data establish the importance of the G-CSF-R C-terminus in STAT3 activation in primary cells, which has implications for understanding why truncated G-CSF-R derived from SCN patients are defective in maturation signaling.


Blood ◽  
2001 ◽  
Vol 98 (12) ◽  
pp. 3309-3314 ◽  
Author(s):  
S. Bradley Forlow ◽  
Jill R. Schurr ◽  
Jay K. Kolls ◽  
Gregory J. Bagby ◽  
Paul O. Schwarzenberger ◽  
...  

Abstract Many mutant mice deficient in leukocyte adhesion molecules display altered hematopoiesis and neutrophilia. This study investigated whether peripheral blood neutrophil concentrations in these mice are elevated as a result of accumulation of neutrophils in the circulation or altered hematopoiesis mediated by a disrupted regulatory feedback loop. Chimeric mice were generated by transplanting various ratios of CD18+/+ and CD18−/− unfractionated bone marrow cells into lethally irradiated wild-type mice, resulting in approximately 0%, 10%, 50%, 90%, or 100% CD18 null neutrophils in the blood. The presence of only 10% CD18+/+ neutrophils was sufficient to prevent the severe neutrophilia seen in mice reconstituted with CD18−/− bone marrow cells. These data show that the neutrophilia in CD18−/− mice is not caused by enhanced neutrophil survival or the inability of neutrophils to leave the vascular compartment. In CD18−/−, CD18−/−E−/−, CD18−/−P−/−, EP−/−, and EPI−/− mice, levels of granulocyte colony-stimulating factor (G-CSF) and interleukin-17 (IL-17) were elevated in proportion to the neutrophilia seen in these mice, regardless of the underlying mutation. Antibiotic treatment or the propensity to develop skin lesions did not correlate with neutrophil counts. Blocking IL-17 or G-CSF function in vivo significantly reduced neutrophil counts in severely neutrophilic mice by approximately 50% (P < .05) or 70% (P < .01), respectively. These data show that peripheral blood neutrophil numbers are regulated by a feedback loop involving G-CSF and IL-17 and that this feedback loop is disrupted when neutrophils cannot migrate into peripheral tissues.


1993 ◽  
Vol 13 (12) ◽  
pp. 7774-7781
Author(s):  
F Dong ◽  
C van Buitenen ◽  
K Pouwels ◽  
L H Hoefsloot ◽  
B Löwenberg ◽  
...  

The granulocyte colony-stimulating factor receptor (G-CSF-R) transduces signals important for the proliferation and maturation of myeloid progenitor cells. To identify functionally important regions in the cytoplasmic domain of the G-CSF-R, we compared the actions of the wild-type receptor, two mutants, and a natural splice variant in transfectants of the mouse pro-B cell line BAF3 and two myeloid cell lines, 32D and L-GM. A region of 55 amino acids adjacent to the transmembrane domain was found to be sufficient for generating a growth signal. The immediate downstream sequence of 30 amino acids substantially enhanced the growth signaling in the three cell lines. In contrast, the carboxy-terminal part of 98 amino acids strongly inhibited growth signaling in the two myeloid cell lines but not in BAF3 cells. Truncation of this region lead to an inability of the G-CSF-R to transduce maturation signals in L-GM cells. An alternative carboxy tail present in a splice variant of the G-CSF-R also inhibited growth signaling, notably in both the myeloid cells and BAF3 cells, but appeared not to be involved in maturation.


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