Interferon-gamma induces phosphorylation of multiple small-molecular-weight proteins in U937 cells.
This study examines the hypothesis that interferon-gamma (IFN-gamma) induces protein phosphorylation as part of the signal transduction pathway used to activate U937 cells. U937 cells labeled with 32Pi were treated with IFN-gamma, proteins were separated by two-dimensional polyacrylamide gel electrophoresis, and the pattern of protein phosphorylation was determined by autoradiography and computer-assisted two-dimensional densitometry. IFN-gamma (100 U/ml) induced phosphorylation of multiple proteins between 15 and 60 min, and the proteins were all dephosphorylated by 120 min. The pattern of proteins phosphorylated in the presence of ionomycin or PMA differed from that of IFN-gamma. Inhibition of protein kinase C activity by 1-(5-isoquinolinesulfonyl)2-methyl piperazine (H-7), inhibition of calcium-calmodulin-dependent protein kinase by N-(6-aminohexyl)-5-chloro-naphthalenesulfonamide (W-7), and inhibition of calcium redistribution by 8-(diethylamino)-octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8) did not inhibit the majority of IFN-gamma-induced protein phosphorylation. These data indicate that IFN-gamma induces protein phosphorylation in U937 cells by activation of a kinase different from, or in addition to, protein kinase C or calcium-calmodulin-dependent kinase.
Schepers
T M
TM
Department of Biochemistry, University of Louisville School of Medicine, KY.
Klein
J B
JB
Feldhoff
P W
PW
Dean
W L
WL
McLeish
K R
KR
D001798:Blood Proteins / Q000187:drug effects* / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002460:Cell Line; D015180:Electrophoresis, Gel, Two-Dimensional; D007371:Interferon-gamma / Q000494:pharmacology*; D008970:Molecular Weight; D010766:Phosphorylation; D011494:Protein Kinases / Q000502:physiology*; D011994:Recombinant Proteins; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors
D001798:Blood Proteins; D011994:Recombinant Proteins; D007371:Interferon-gamma; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases