Activation of Akt kinase by granulocyte colony-stimulating factor (G-CSF): evidence for the role of a tyrosine kinase activity distinct from the janus kinases

Blood ◽  
2000 ◽  
Vol 95 (5) ◽  
pp. 1656-1662 ◽  
Author(s):  
Fan Dong ◽  
Andrew C. Larner
Keyword(s):  
Amino Acids ◽  
Tyrosine Kinases ◽  
Cell Surface Receptor ◽  
Signaling Cascades ◽  
Granulocyte Colony Stimulating Factor ◽  
Colony Stimulating Factor ◽  
Cytokine Activation ◽  
Stimulating Factor ◽  
Stimulation Of ◽  
Factor G

Activation of the serine/threonine kinase Akt has been shown to be a critical component for growth factor and cytokine stimulation of cell survival. Although some of the immediate upstream activators of Akt have been defined, the roles of tyrosine kinases in the activation of Akt are not well delineated. Granulocyte colony-stimulating factor (G-CSF) regulates the proliferation, differentiation, and survival of neutrophilic granulocytes. G-CSF exerts its actions by stimulating several signaling cascades after binding its cell surface receptor. Both Jak (Janus) and Src families of tyrosine kinases are stimulated by incubation of cells with G-CSF. In this report, we show that G-CSF stimulation of cells leads to activation of Akt. The membrane-proximal 55 amino acids of the G-CSF receptor cytoplasmic domain are sufficient for mediating Akt activation. However, activation of Akt appears to be downregulated by the receptor's carboxy-terminal region of 98 amino acids, a region that has been shown to be truncated in some patients with acute myeloid leukemia associated with severe congenital neutropenia. Furthermore, we demonstrate that G-CSF–induced activation of Akt requires the activities of Src family kinases but can be clearly dissociated from G-CSF–stimulated activation of Stats (signal transducers and activators of transcripton) by the Jak kinases. Thus, cytokine activation of the Jak/Stat and other signaling cascades can be functionally separated.

scholarly journals Distinct regions of the granulocyte colony-stimulating factor receptor are required for tyrosine phosphorylation of the signaling molecules JAK2, Stat3, and p42, p44MAPK

Blood ◽  
1995 ◽  
Vol 86 (10) ◽  
pp. 3698-3704 ◽  
Author(s):  
SE Nicholson ◽  
U Novak ◽  
SF Ziegler ◽  
JE Layton
Keyword(s):  
Amino Acids ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Transmembrane Domain ◽  
Cytoplasmic Domain ◽  
Signaling Molecules ◽  
Granulocyte Colony Stimulating Factor ◽  
Colony Stimulating Factor ◽  
Kinase Activation ◽  
Stimulating Factor

The protein tyrosine kinases JAK1 and JAK2 are phosphorylated tyrosine after the interaction of granulocyte colony-stimulating factor (G-CSF) with its transmembrane receptor. So too is Stat3, a member of the STAT family of transcriptional activators thought to be activated by the JAK kinases. Truncated G-CSF receptor (G-CSF-R) mutants were used to determine the different regions of the cytoplasmic domain necessary for tyrosine phosphorylation of the signaling molecules JAK2, Stat3, and p42, p44MAPK. We have shown that G-CSF-induced tyrosine phosphorylation and kinase activation of JAK2 requires the membrane proximal 57 amino acids of the cytoplasmic domain. In contrast, maximal Stat3 tyrosine phosphorylation required amino acids 96 to 183 of the G-CSF-R cytoplasmic domain, Stat3 DNA binding could occur with a receptor truncated 96 amino acids from the transmembrane domain and containing a single tyrosine residue, but was reduced in comparison with the full- length receptor. Together with the tyrosine phosphorylation of Stat3, this finding suggests that additional Stat3 does not appear to be required for proliferation. MAP kinase tyrosine phosphorylation correlated with both the proliferative response and JAK2 activation.

scholarly journals Tryptophan 650 of human granulocyte colony-stimulating factor (G-CSF) receptor, implicated in the activation of JAK2, is also required for G- CSF-mediated activation of signaling complexes of the p21ras route

Blood ◽  
1996 ◽  
Vol 87 (6) ◽  
pp. 2148-2153 ◽  
Author(s):  
RM Barge ◽  
JP de Koning ◽  
K Pouwels ◽  
F Dong ◽  
B Lowenberg ◽  
...  
Keyword(s):  
Amino Acids ◽  
Distal Region ◽  
Proximal Region ◽  
Granulocyte Colony Stimulating Factor ◽  
Colony Stimulating Factor ◽  
Tyrosine Residues ◽  
Membrane Proximal Region ◽  
Stimulating Factor ◽  
Proliferative Signaling ◽  
Factor G

Granulocyte colony-stimulating factor (G-CSF) induces rapid phosphorylation of JAK kinases as well as activation of the p21ras route through interaction with its specific receptor (G-CSF-R). The cytoplasmic membrane-proximal region of G-CSF-R (amino acids 631 to 684) is necessary for proliferation induction and activation of JAK2. In contrast, activation of Shc and Syp, signaling molecules implicated in the p21ras signaling route, depends on the phosphorylation of tyrosine residues located in the membrane-distal region (amino acids 685 to 813) of G-CSF-R. We investigated whether G-CSF-induced activation of signaling complexes of the p21ras route depends on the function of the membrane-proximal cytoplasmic region of G-CSF-R. A G- CSF-R mutant was constructed in which tryptophan 650 was replaced by arginine and expressed in BAF3 cells (BAF/W650R). In contrast to BAF3 cell transfectants expressing wild-type G-CSF-R, BAF/W650-R cells did not proliferate and did not show activation of JAK2, STAT1, or STAT3 in response to G-CSF. Immunoprecipitations with anti-Shc and anti-Grb2 antisera showed that mutant W650R also failed to activate Syp and Shc. These data indicate that the membrane-proximal cytoplasmic domain of G- CSF-R is not only crucial for proliferative signaling and activation of JAK2 and STATs, but is also required for activation of the p21ras route, which occurs via the membrane-distal region of G-CSF-R.

scholarly journals Can granulocyte colony stimulating factor (G-CSF) ameliorate acetaminophen-induced hepatotoxicity?

2021 ◽  
pp. 096032712110085
Author(s):  
EA Ahmed ◽  
AM Abd-Eldayem ◽  
E Ahmed
Keyword(s):  
Liver Damage ◽  
Liver Toxicity ◽  
Serum Levels ◽  
Hepatic Tissue ◽  
Granulocyte Colony Stimulating Factor ◽  
Colony Stimulating Factor ◽  
Oxidative Markers ◽  
Stimulating Factor ◽  
New Strategies ◽  
Factor G

Acetaminophen (APAP) is often used as an antipyretic and analgesic agent. Overdose hepatotoxicity, which often results in liver cell failure and liver transplantation, is a severe complication of APAP usage. To save the liver and save lives from acute liver damage caused by APAP, the search for new strategies for liver defense is important. Wistar rats have been used for the induction of APAP hepatotoxicity. Elevated levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were evaluated for liver toxicity. In addition, the levels of hepatic tissue oxidative markers such as malondialdehyde (MDA), nitric oxide (NO) increased while glutathione (GSH) was depleted and catalase (CAT) activity was curtailed. The biochemical findings were consistent with the changes in histology that suggested liver damage and inflammation. Treated rats with N-acetylcysteine (N-AC) and granulocyte colony stimulating factor (G-CSF) showed a decrease in serum levels of ALT, AST and LDH, while the level of ALP in the G-CSF group was still high. After administration of APAP, treatment with N-AC or G-CSF substantially reduced the level of MDA and NO while maintaining the GSH content and CAT activity. Treatment with N-AC and G-CSF after administration of APAP has also attenuated inflammation and hepatocytes necrosis. The results of this study showed that G-CSF could be viewed as an alternative hepatoprotective agent against APAP-induced acute liver injury compared to N-AC.

scholarly journals G-CSF receptor activation of the Src kinase Lyn is mediated by Gab2 recruitment of the Shp2 phosphatase

Blood ◽  
2011 ◽  
Vol 118 (4) ◽  
pp. 1077-1086 ◽  
Author(s):  
Muneyoshi Futami ◽  
Quan-sheng Zhu ◽  
Zakary L. Whichard ◽  
Ling Xia ◽  
Yuehai Ke ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Src Kinase ◽  
Receptor Activation ◽  
Phosphorylation Sites ◽  
Granulocyte Colony Stimulating Factor ◽  
Colony Stimulating Factor ◽  
Stimulating Factor ◽  
In Cells

Abstract Src activation involves the coordinated regulation of positive and negative tyrosine phosphorylation sites. The mechanism whereby receptor tyrosine kinases, cytokine receptors, and integrins activate Src is not known. Here, we demonstrate that granulocyte colony-stimulating factor (G-CSF) activates Lyn, the predominant Src kinase in myeloid cells, through Gab2-mediated recruitment of Shp2. After G-CSF stimulation, Lyn dynamically associates with Gab2 in a spatiotemporal manner. The dephosphorylation of phospho-Lyn Tyr507 was abrogated in Shp2-deficient cells transfected with the G-CSF receptor but intact in cells expressing phosphatase-defective Shp2. Auto-phosphorylation of Lyn Tyr396 was impaired in cells treated with Gab2 siRNA. The constitutively activated Shp2E76A directed the dephosphorylation of phospho-Lyn Tyr507 in vitro. Tyr507 did not undergo dephosphorylation in G-CSF–stimulated cells expressing a mutant Gab2 unable to bind Shp2. We propose that Gab2 forms a complex with Lyn and after G-CSF stimulation, Gab2 recruits Shp2, which dephosphorylates phospho-Lyn Tyr507, leading to Lyn activation.

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