Activation of the neutrophil by calcium-mobilizing ligands. I. A chemotactic peptide and the lectin concanavalin A stimulate superoxide anion generation but elicit different calcium movements and phosphoinositide remodeling.
The relevance of phosphoinositide remodeling to calcium movements and to the physiological response of superoxide anion (O2-) generation was probed in neutrophils stimulated by the chemotactic peptide fMet-Leu-Phe and the lectin concanavalin A. fMet-Leu-Phe and concanavalin A triggered O2- generation but elicited different patterns of calcium mobilization and phosphoinositide remodeling. fMet-Leu-Phe (10(-7) M) triggered a rise in cytosolic calcium by mobilization of intracellular calcium (fura-2) and increased calcium permeability (45Ca uptake), while concanavalin A (100 micrograms/ml) elicited a rise in cytosolic calcium, primarily by uptake of extracellular calcium (45Ca uptake). fMet-Leu-Phe triggered rapid breakdown of phosphatidylinositol 4,5-bisphosphate (PIP2), phosphatidylinositol 4-phosphate and phosphatidylinositol, and generation of inositol 1,4,5-trisphosphate (IP3). In contrast concanavalin A triggered breakdown of phosphatidylinositol, but not PIP2, nor was there a significant increase in IP3. However, both fMet-Leu-Phe and concanavalin A triggered a rapid biphasic increase in levels of labeled diacylglycerol (in [3H]arachidonate or [14C]glycerol prelabeled cells) and a 3-fold increase in [32P] phosphatidic acid. These results are concordant with a role for PIP2 breakdown and generation of IP3 specifically in intracellular calcium mobilization but not for other aspects of the signaling pathway for O2- generation. Calcium permeability changes were associated with elevated diacylglycerol and [32P]phosphatidic acid, although a cause and effect relationship is not apparent. Ligands such as concanavalin A enhance cytosolic calcium and trigger generation of O2- without significant PIP2 remodeling; elevated diacylglycerol and cytosolic calcium are the common events associated with ligand-induced O2- generation.
Korchak
H M
HM
Department of Medicine, New York University Medical Center, New York 10016.
Vosshall
L B
LB
Zagon
G
G
Ljubich
P
P
Rich
A M
AM
Weissmann
G
G
D001572:Benzofurans; D002118:Calcium / Q000097:blood*; D003208:Concanavalin A / Q000494:pharmacology*; D016257:Fura-2; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010539:Permeability; D010716:Phosphatidylinositols / Q000097:blood*; D013481:Superoxides / Q000097:blood*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013997:Time Factors
D001572:Benzofurans; D010716:Phosphatidylinositols; D003208:Concanavalin A; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D016257:Fura-2