Activation and mitogen-activated protein kinase regulation of transcription factors Ets and NF-kappaB in Mycobacterium-infected macrophages and role of these factors in tumor necrosis factor alpha and nitric oxide synthase 2 promoter function.
Previous studies have shown that primary murine macrophages infected with Mycobacterium avium produced lower levels of tumor necrosis factor alpha (TNF-alpha) and inducible nitric oxide synthase 2 (NOS2) compared to cells infected with nonpathogenic Mycobacterium smegmatis. TNF-alpha and NOS2 levels correlated with and were dependent on the activation of mitogen-activated protein kinases (MAPKs) p38 and extracellular signal-regulated kinase 1/2 (ERK1/2). To define the macrophage transcriptional responses dependent on ERK1/2 activation following a mycobacterial infection, we used RAW 264.7 cells transfected with a TNF-alpha or NOS2 promoter vector. We determined that macrophages infected with M. avium compared to M. smegmatis showed diminished TNF-alpha and NOS2 promoter activity. A more pronounced difference in promoter activity was observed when only the consensus ETS and NF-kappaB binding sites were used as promoters. Mutational analysis of the ETS and NF-kappaB binding sites present on the TNF-alpha and NOS2 promoters, respectively, showed that these sites were essential for a functional promoter. Moreover, the Ets/Elk but not the NF-kappaB transcriptional response was dependent on ERK1/2. This correlated with the requirement for ERK1/2 in TNF-alpha but not NOS2 promoter activity. Our data indicate that the increased Ets/Elk and NF-kappaB promoter activities associated with M. smegmatis-infected macrophages are responsible, at least in part, for the increased TNF-alpha and NOS2 production observed in these infected cells and that ERK1/2 is required for Ets/Elk activity and full TNF-alpha production.
Lee
Seong-Beom
SB
Department of Biological Sciences, Center for Tropical Disease Research and Training, University of Notre Dame, IN 46556, USA.
Schorey
Jeffrey S
JS
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009154:Mutation; D009162:Mycobacterium avium / Q000472:pathogenicity*; D020102:Mycobacterium smegmatis / Q000502:physiology; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D051996:Transcription Factor RelA / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D051996:Transcription Factor RelA; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3