Lipopolysaccharide-induced biphasic inositol 1,4,5-trisphosphate response and tyrosine phosphorylation of 140-kilodalton protein in mouse peritoneal macrophages.
We previously showed that a relatively high dose of LPS induced the selective translocation of protein kinase C-beta (PKC-beta) in LPS-responsive mouse macrophages. This result suggested that phosphatidylinositol-specific phospholipase C (PLC) might be activated in the upstream of PKC-beta. Stimulation of C3H/HeN mouse macrophages by LPS induced the characteristic phosphatidylinositol-1,4,5-trisphosphate (IP3) response, that is, a biphasic response consisting of a rapid increase occurring within the first 1 min, and another increase beginning at around 1 min after stimulation. Only the first response was disappeared when cells were treated with a platelet-activating factor receptor antagonist. LPS-inducible TNF-alpha gene activation, however, was not suppressed by the same antagonist, but suppressed by PKC inhibitors. LPS-stimulated macrophage lysates showed tyrosine phosphorylation of some proteins, and the strongest phosphorylation was observed at molecular mass of 140 kDa. The phosphorylation of this protein started at 40 s after LPS stimulation and continued to increase. Anti-PLC-gamma2 Ab seemed to recognize the same protein as the tyrosine-phosphorylated 140-kDa protein. A low dose of LPS (1 ng/ml) could not induce the tyrosine phosphorylation of this protein. Furthermore, LPS induced only the first phase change, but not the second phase increase in LPS-hyporesponsive C3H/HeJ mouse macrophages. These results indicate that the first phase rapid IP3 change, which is also seen in HeJ macrophages, is mediated via a platelet-activating factor receptor, and is not responsible for TNF-alpha production, while the second phase change mediated by a molecule other than CD14 is responsible for PKC-beta translocation and TNF-alpha production. The results also suggest that the later IP3 change is considered to be mediated through a gamma2 type of phosphatidylinositol-specific PLC.
Shinji
H
H
Department of Microbiology II, The Jikei University School of Medicine, Tokyo, Japan.
Akagawa
K S
KS
Tsuji
M
M
Maeda
M
M
Yamada
R
R
Matsuura
K
K
Yamamoto
S
S
Yoshida
T
T
D000818:Animals; D016227:Benzoquinones; D004305:Dose-Response Relationship, Drug; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D047029:Lactams, Macrocyclic; D008070:Lipopolysaccharides / Q000494:pharmacology*; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008970:Molecular Weight; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000378:metabolism*; D019000:Phosphotyrosine / Q000378:metabolism*; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011809:Quinones / Q000494:pharmacology; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism
D016227:Benzoquinones; D007527:Isoenzymes; D047029:Lactams, Macrocyclic; D008070:Lipopolysaccharides; D010750:Phosphoproteins; D010980:Platelet Membrane Glycoproteins; D011809:Quinones; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D017828:Rifabutin; D019000:Phosphotyrosine; C020754:herbimycin; D015544:Inositol 1,4,5-Trisphosphate; D011505:Protein-Tyrosine Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma