Ligation of the alpha2M* signaling receptor regulates synthesis of cytosolic phospholipase A2.
We have studied the regulation of cytosolic phospholipase A2 (cPLA2) synthesis in macrophages stimulated with receptor-recognized forms of alpha2-macroglobulin (alpha2M*). [35S]methionine-labeled cells were stimulated with alpha2M* and [35S]cPLA2 was immunoprecipitated with a monoclonal antibody directed against cPLA2. The precipitates were electrophoresed, immunoblotted, cPLA2 detected by Enhanced Chemifluorescence, and its radioactivity determined. Stimulation of cells with alpha2M* caused a two- to threefold increase in cPLA2 synthesis compared to buffer-treated cells which was consistently maximal at 200 pM of alpha2M*. Actinomycin D or cycloheximide treatment of cells drastically reduced alpha2M*-induced cPLA2 synthesis. Likewise, inhibition of protein kinase C with chelerythrin, farnesyl transferase with manumycin A, MEK kinase with U0126, Erk1/2 kinases with PD98059, p38MAPK with SB203580, PI 3-kinase with wortmannin or LY294002, p70s6k with rapamycin, or depletion of [Ca2+]i with either BAPTA/AM or EGTA drastically reduced alpha2M* induction of cPLA2. Inhibition of NFKB activation with BAY11-7182 or PGA1 also abolished alpha2M* induction of cPLA2. We conclude that alpha2M*-induced cPLA2 synthesis is controlled by [Ca2+]i levels, tyrosine kinase activity, the p21ras-dependent MAPK and PI 3-kinase downstream signaling pathways, and regulation of NFkappaB.
Misra
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UK
Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Pizzo
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D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D051231:Farnesyltranstransferase; D008024:Ligands; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010741:Phospholipases A / Q000096:biosynthesis*; D054467:Phospholipases A2; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism*; D019893:Ribosomal Protein S6 Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D000511:alpha-Macroglobulins / Q000494:pharmacology
D019883:Alkyl and Aryl Transferases; D002118:Calcium; D003513:Cycloheximide; D003609:Dactinomycin; D051231:Farnesyltranstransferase; D008024:Ligands; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010741:Phospholipases A; D054467:Phospholipases A2; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D016283:Proto-Oncogene Proteins p21(ras); D011971:Receptors, Immunologic; D019893:Ribosomal Protein S6 Kinases; D000511:alpha-Macroglobulins; C482127:Map2k1 protein, mouse