Activation of Ras and mitogen-activated protein kinase pathway by terminal complement complexes is G protein dependent.
Assembly of terminal complement complexes (TCC) C5b-7, C5b-8, and C5b-9 on target cells during acute and chronic inflammation induces hydrolysis of plasma membrane phospholipids and heterotrimeric G protein activation. TCC also stimulate a variety of cellular activities, which include cytokine synthesis, proto-oncogene activation, and mitotic signaling. Now we report that sublytic TCC induced Ras, Raf-1, and extracellular signal-regulated kinase (ERK) 1 activation in JY25 B cell line. When cells were exposed to C5b-9, GTP-bound Ras in anti-C5b-9 immunoprecipitates was increased 3.2-fold at 2 min, while GTP-bound Ras in anti-Ras immunoprecipitates was increased 2-fold at 10 min. Both C5b-9 and C5b-7, but not C5b6, increased Raf-1 kinase activity maximum 3.3-fold at 2 min and 2.8-fold at 5 min, respectively. ERK1 activity was 2-fold increased by C5b-9 at 2 min and by C5b-7 at 10 min, over the C5b6 level. The role of mitogen-activated protein kinase (MAPK) pathway on TCC-inducible mitotic signaling was evaluated by assessing DNA synthesis and activator protein 1 (AP-1) DNA-binding activity. The MAPK/ERK-specific inhibitor PD 098,059 abolished the C5b-9-induced DNA synthesis. Involvement of G protein in the activation of MAPK pathway by TCC was indicated by inhibition of Raf-1 and ERK1 kinase activity, as well as the DNA synthesis by pretreatment of cells with pertussis toxin. Overexpression of beta-adrenergic receptor kinase 1 carboxyl-terminal peptide in JY25 cells also inhibited Raf-1 and ERK1 activity, indicating a direct involvement of G betagamma subunits in the signal transduction generated through activation of MAPK pathway by TCC assembly in the plasma membrane.
Niculescu
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University of Maryland, School of Medicine, Department of Pathology, Baltimore 21201, USA.
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van Biesen
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Shin
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D001402:B-Lymphocytes / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D015938:Complement Membrane Attack Complex / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation; D005419:Flavonoids / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D037342:Pertussis Toxin; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000378:metabolism; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D051552:beta-Adrenergic Receptor Kinases
D015938:Complement Membrane Attack Complex; D005419:Flavonoids; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D018808:Transcription Factor AP-1; D010566:Virulence Factors, Bordetella; D004247:DNA; D037342:Pertussis Toxin; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one