Continuous phosphorylation of both the 47 and the 49 kDa proteins occurs during superoxide production by neutrophils.
Neutrophils stimulated with 4 beta-phorbol 12-myristate 13-acetate release large quantities of superoxide (O2-) and exhibit an intense phosphorylation of two proteins with molecular masses of approx. 47 and 49 kDa. Treatment of unstimulated cells with antagonists of protein kinase C (e.g., staurosporine; 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7)) is known to inhibit both of these phenomena upon stimulation. These antagonists of PKC also cause a rapid cessation of O2- release when added to cells that are already stimulated. In this paper, we report that the addition of staurosporine or H-7 to stimulated neutrophils resulted in a rapid loss of 32P from both the 47 and the 49 kDa phosphoprotein bands, as detected by autoradiography. This suggests that these two proteins may be regulated by a continual cycle of phosphorylation and dephosphorylation in the stimulated cell, with the phosphorylation reactions predominating, or undergo a rapid degradation subsequent to phosphorylation. Either explanation is consistent with the view that protein kinase C activity is necessary to both initiate and maintain O2- production in neutrophils stimulated with tumor promoters.
Heyworth
P G
PG
Department of Cell Physiology, Boston Biomedical Research Institute, MA 02114.
Badwey
J A
JA
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D006168:Guinea Pigs; D007546:Isoquinolines / Q000494:pharmacology; D008970:Molecular Weight; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D019311:Staurosporine; D013481:Superoxides / Q000378:metabolism*
D000470:Alkaloids; D007546:Isoquinolines; D010879:Piperazines; D013481:Superoxides; D010758:Phosphorus; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D019311:Staurosporine; D010100:Oxygen