Activation of ERK1/2 and TNF-alpha production are mediated by calcium/calmodulin, and PKA signaling pathways during Mycobacterium bovis infection.
Mycobacterium bovis bacillus Calmette-Guérin (BCG)-induced tumor necrosis factor (TNF)-alpha secretion via an extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase-dependent mechanism is an important host defence mechanism against Mycobacterium tuberculosis in human monocytes. We now define distinct signaling pathways that regulate induction of TNF-alpha and activation of ERK1/2 by intracellular signaling mechanisms during M. bovis infection. We determined that M. bovis BCG-induced ERK 1/2 activation occurs through a mechanism that requires intracellular calcium and likely involves a calmodulin-sensitive step. In contrast, M. bovis BCG can induce p38 mapk activation by a calcium (Ca2+)/calmodulin-independent mechanism. Interestingly, we present evidence that M. bovis BCG activates protein kinase A (PKA), since pretreatment of monocytes with H-89, a inhibitor of PKA activity, blocked the ability of M. bovis BCG to induce ERK1/2 activation. These results were further supported by the fact that treatment of cells with KT5720, another well-described inhibitor of PKA activity, significantly diminished the effect of M. bovis BCG on ERK1/2 activation. Furthermore, secretion of TNF-alpha in M. bovis-infected human monocytes was also dependent on Ca2+/calmodulin, and PKA pathways. Finally, addition of H-89 significantly diminished TNF-alpha mRNA expression in M. bovis-infected human monocytes. These results indicate that the Ca2+/calmodulin, and PKA pathways play important regulatory roles in monocyte signaling upon M. bovis infection.
Méndez-Samperio
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Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, IPN, Carpio y Plan de Ayala, 11340 México, DF, México. pmendezs@bios.encb.ipn.mx
Trejo
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Miranda
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D015153:Blotting, Western / Q000379:methods; D002118:Calcium / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology; D002147:Calmodulin / Q000502:physiology*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000382:microbiology; D009163:Mycobacterium bovis; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013449:Sulfonamides / Q000494:pharmacology; D014376:Tuberculosis / Q000378:metabolism / Q000382:microbiology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
D002147:Calmodulin; D002614:Chelating Agents; D007546:Isoquinolines; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D013449:Sulfonamides; D014409:Tumor Necrosis Factor-alpha; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D004492:Edetic Acid; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D002118:Calcium