Isoquinolinesulfonamide protein kinase inhibitors H7 and H8 enhance the effects of granulocyte-macrophage colony-stimulating factor (GM-CSE) on neutrophil function and inhibit GM-CSF receptor internalization.
Human granulocyte-macrophage colony-stimulating factor (GM-CSF) increases neutrophil surface expression of the cellular adhesion molecule CD11b and primes the respiratory burst stimulated by the bacterial peptide f-met-leuphe (FMLP). We have examined the effects of the isoquinolinesulfonamide protein kinase inhibitors H7 and H8 on these functions of GM-CSF using whole blood assays. Concentrations of H7 and H8 that inhibited the 12-O-tetradecanoyl-phorbol-13-acetate (TPA) stimulated upregulation of CD11b expression and activation of the respiratory burst, both augmented the effects of GM-CSF. H7 and H8 enhanced the GM-CSF-stimulated increase in CD11b expression to 215% +/- 10% (P less than .05) and 233% +/- 45% (P less than .05), respectively, of the value obtained with GM-CSF alone. The GM-CSF priming of the FMLP-stimulated oxidative burst was increased to 190% +/- 44% (P less than .01) by preincubation with H7 and to 172% +/- 25% (P less than .01) with H8. Preincubation with H8 did not affect overall binding of 125I-GM-CSF to neutrophils, but inhibited GM-CSF receptor internalization after ligand binding (P less than .05). These data indicate that the effects of GM-CSF are not mediated by protein kinase C and that a phosphorylation event down-modulates the neutrophil response to GM-CSF. It suggests that internalization of the receptor-ligand complex is not a rate-limiting step in signal transduction, and that regulation of the rate of internalization may be an important level of control of the activity of GM-CSF.
Khwaja
A
A
Department of Haematology, University College Middlesex School of Medicine, London, UK.
Roberts
P J
PJ
Jones
H M
HM
Yong
K
K
Jaswon
M S
MS
Linch
D C
DC
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D003115:Colony-Stimulating Factors / Q000378:metabolism / Q000494:pharmacology*; D005434:Flow Cytometry; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D006133:Growth Substances / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000097:blood; D007546:Isoquinolines / Q000494:pharmacology*; D007700:Kinetics; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000502:physiology*; D016184:Receptors, Colony-Stimulating Factor; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology
D015703:Antigens, CD; D003115:Colony-Stimulating Factors; D006133:Growth Substances; D007546:Isoquinolines; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011956:Receptors, Cell Surface; D016184:Receptors, Colony-Stimulating Factor; D011994:Recombinant Proteins; D009240:N-Formylmethionine Leucyl-Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; D006861:Hydrogen Peroxide