Direct stimulation by tyrosine phosphorylation of microtubule-associated protein (MAP) kinase activity by granulocyte-macrophage colony-stimulating factor in human neutrophils

摘要: Human polymorphonuclear neutrophils exhibit a low level of the microtubule-associated protein kinase (MAPK) activity. This enzymic activity is enhanced up to 3-fold upon cell stimulation with human haematopoietic hormone granulocyte-macrophage colony-stimulating factor (GM-CSF). demonstrated both in whole-cell lysates and DEAE-anion-exchange semi-purified fractions prepared from GM-CSF-stimulated neutrophils, by assaying against either myelin basic or phosphoacceptor peptide that bears specific phosphorylation site MAPK natural substrate. Similarly, tyrosine residues, as found immunoblots using anti-phosphotyrosine antibodies, follows similar time- dose-response curves activation. Pretreatment cells inhibitor genistein abrogates above-mentioned effect, whereas phosphatase okadaic acid enhances basal activities. Likewise, diminished genistein-treated acid-treated cells. We conclude present it stimulated GM-CSF. most likely due residues triggered binding GM-CSF its receptors.