Stimulus-response coupling in FMLP-stimulated U937 monocytes: effect of differentiation on Gi2 expression.
The effect of differentiation on FMLP-stimulated InsP production and G-protein expression was investigated in U937 monocytes. FMLP (0.01-10 microM) stimulated [3H]InsP production in dimethyl sulphoxide-differentiated, but not in immature, U937 cells. Ionomycin (1 and 10 microM) stimulated [3H]InsP production equally well in both cell types. The FMLP response was blocked by pertussis toxin (100 ng/ml for 4 h) which catalysed [32P]ADP ribosylation of a 40 kDa 'Gi-like' G-protein alpha subunit in these cells. This protein was also identified immunologically using anti-peptide antibodies that detect 'Gi-like' alpha subunits (SG2) or Gi2 alpha specifically (LE2). With LE2 a 5-fold increase in Gi2 alpha levels was seen following differentiation of the cells, suggesting that FMLP receptor expression is accompanied by an increase in the G-protein with which these receptors interact.
Pollock
K
K
Bioscience II, ICI Pharmaceuticals, Alderley Park, Glasgow, U.K.
Creba
J
J
Mitchell
F
F
Milligan
G
G
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D009000:Monocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D037342:Pertussis Toxin; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D007295:Inositol Phosphates; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D015759:Ionomycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins