Granulocyte colony-stimulating factor-induced dephosphorylation of a 45 kD cytosolic protein in HL-60 cells differentiating into neutrophils.
Granulocyte colony-stimulating factor (G-CSF)-induced alteration of phosphoprotein during differentiation of HL-60 cells was studied. From the two-dimensional gel electrophoresis analysis of phosphoproteins, a 45 kD phosphoprotein in the cytosolic fraction of DMSO-pretreated HL-60 cells was rapidly dephosphorylated by the addition of G-CSF. This 45 kD phosphoprotein migrated into four or five spots between 4.5 and 5.5 pI. The dephosphorylation of 45 kD protein was observed within at least 10 min and reached a maximum at 60 min. Phosphoamino acid analysis showed that only serine residue of 45 kD phosphoprotein was phosphorylated, suggesting that G-CSF induced an activation of serine phosphatase. Furthermore, Staurosporine and calphostin C inhibited the phosphorylation of 45 kD protein, suggesting that protein kinase C or its downstream kinase(s) is involved in the phosphorylation of 45 kD protein. These results indicate that G-CSF causes dephosphorylation of a 45 kD cytosolic phosphoprotein which may play a role in signal transduction of G-CSF.
National Institute of Health Sciences, Tokyo, Japan.
T
T
Yamaguchi
T
T
Oshizawa
T
T
Yamaguchi
K
K
Suzuki
Y
Y
Yamamoto
T
T
Hayakawa
D002454:Cell Differentiation / Q000502:physiology; D003600:Cytosol / Q000378:metabolism*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D018922:HL-60 Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D009504:Neutrophils / Q000166:cytology*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011994:Recombinant Proteins
D010750:Phosphoproteins; D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor; D004121:Dimethyl Sulfoxide