scholarly journals Activation and Mitogen-Activated Protein Kinase Regulation of Transcription Factors Ets and NF-κB in Mycobacterium-Infected Macrophages and Role of These Factors in Tumor Necrosis Factor Alpha and Nitric Oxide Synthase 2 Promoter Function

2005 ◽  
Vol 73 (10) ◽  
pp. 6499-6507 ◽  
Author(s):  
Seong-Beom Lee ◽  
Jeffrey S. Schorey

ABSTRACT Previous studies have shown that primary murine macrophages infected with Mycobacterium avium produced lower levels of tumor necrosis factor alpha (TNF-α) and inducible nitric oxide synthase 2 (NOS2) compared to cells infected with nonpathogenic Mycobacterium smegmatis. TNF-α 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-α or NOS2 promoter vector. We determined that macrophages infected with M. avium compared to M. smegmatis showed diminished TNF-α and NOS2 promoter activity. A more pronounced difference in promoter activity was observed when only the consensus ETS and NF-κB binding sites were used as promoters. Mutational analysis of the ETS and NF-κB binding sites present on the TNF-α and NOS2 promoters, respectively, showed that these sites were essential for a functional promoter. Moreover, the Ets/Elk but not the NF-κB transcriptional response was dependent on ERK1/2. This correlated with the requirement for ERK1/2 in TNF-α but not NOS2 promoter activity. Our data indicate that the increased Ets/Elk and NF-κB promoter activities associated with M. smegmatis-infected macrophages are responsible, at least in part, for the increased TNF-α and NOS2 production observed in these infected cells and that ERK1/2 is required for Ets/Elk activity and full TNF-α production.

2006 ◽  
Vol 74 (6) ◽  
pp. 3381-3386 ◽  
Author(s):  
Michelle A. Parent ◽  
Lindsey B. Wilhelm ◽  
Lawrence W. Kummer ◽  
Frank M. Szaba ◽  
Isis K. Mullarky ◽  
...  

ABSTRACT Pulmonary infection by Yersinia pestis causes pneumonic plague, a rapidly progressing and often fatal disease. To aid the development of safe and effective pneumonic plague vaccines, we are deciphering mechanisms used by the immune system to protect against lethal pulmonary Y. pestis infection. In murine pneumonic plague models, passive transfer of convalescent-phase sera confers protection, as does active vaccination with live Y. pestis. Here, we demonstrate that protection by either protocol relies upon both gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) cytokines classically associated with type 1 cellular immunity. In both protocols, abrogating IFN-γ or TNF-α activity significantly decreases survival and increases the bacterial burden in pulmonary, splenic, and hepatic tissues. Neutralization of either cytokine also counteracts challenge-induced, vaccination-dependent upregulation of nitric oxide synthase 2 (NOS2). Moreover, genetic depletion of NOS2 suppresses protection conferred by serotherapy. We conclude that IFN-γ, TNF-α, and NOS2, key elements of cellular immunity, perform critical protective functions during humoral defense against lethal pulmonary Y. pestis challenge. These observations strongly suggest that plague vaccines should strive to maximally prime both cellular and humoral immunity.


2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Xingzhao Ji ◽  
Xiujuan Zhang ◽  
Heqiao Li ◽  
Lina Sun ◽  
Xuexin Hou ◽  
...  

ABSTRACT The mechanism underlying the pathogenesis of Nocardia is not fully known. The Nfa34810 protein of Nocardia farcinica has been predicted to be a virulence factor. However, relatively little is known regarding the interaction of Nfa34810 with host cells, specifically invasion and innate immune activation. In this study, we aimed to determine the role of recombinant Nfa34810 during infection. We demonstrated that Nfa34810 is an immunodominant protein located in the cell wall. Nfa34810 protein was able to facilitate the uptake and internalization of latex beads coated with Nfa34810 protein into HeLa cells. Furthermore, the deletion of the nfa34810 gene in N. farcinica attenuated the ability of the bacteria to infect both HeLa and A549 cells. Moreover, stimulation with Nfa34810 triggered macrophages to produce tumor necrosis factor alpha (TNF-α), and it also activated mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways by inducing the phosphorylation of ERK1/2, p38, JNK, p65, and AKT in macrophages. Specific inhibitors of ERK1/2, JNK, and NF-κB significantly reduced the expression of TNF-α, which demonstrated that Nfa34810-mediated TNF-α production was dependent upon the activation of these kinases. We further found that neutralizing antibodies against Toll-like receptor 4 (TLR4) significantly inhibited TNF-α secretion. Taken together, our results indicated that Nfa34810 is a virulence factor of N. farcinica and plays an important role during infection. Nfa34810-induced production of TNF-α in macrophages also involves ERK, JNK, and NF-κB via the TLR4 pathway.


2005 ◽  
Vol 79 (16) ◽  
pp. 10147-10154 ◽  
Author(s):  
Davy C. W. Lee ◽  
Chung-Yan Cheung ◽  
Anna H. Y. Law ◽  
Chris K. P. Mok ◽  
Malik Peiris ◽  
...  

ABSTRACT Avian influenza A virus subtype H5N1 can infect humans to cause a severe viral pneumonia with mortality rates of more than 30%. The biological basis for this unusual disease severity is not fully understood. We previously demonstrated that in contrast to human influenza A virus subtypes including H1N1 or H3N2, the H5N1 virus associated with the “bird flu” outbreak in Hong Kong in 1997 (H5N1/97) hyperinduces proinflammatory cytokines, including tumor necrosis factor alpha (TNF-α), in primary human macrophages in vitro. To delineate the molecular mechanisms involved, we analyzed the role of transcription factor NF-κB and cellular kinases in TNF-α dysregulation. H5N1 and H1N1 viruses did not differ in the activation of NF-κB or degradation of IκB-α in human macrophages. However, we demonstrated that unlike H1N1 virus, H5N1/97 strongly activates mitogen-activated protein kinase (MAPK), including p38 MAPK and extracellular signal-regulated kinases 1 and 2. Specific inhibitors of p38 MAPK significantly reduced the H5N1/97-induced TNF-α expression in macrophages. Taken together, our findings suggest that H5N1/97-mediated hyperinduction of cytokines involves the p38 MAPK signaling pathway. These results may provide insights into the pathogenesis of H5N1 disease and rationales for the development of novel therapeutic strategies.


2018 ◽  
Vol 18 (4) ◽  
pp. 305-312 ◽  
Author(s):  
Jing Zhou ◽  
Gang Cheng ◽  
Hua Pang ◽  
Qian Liu ◽  
Ying Liu

Accumulating evidence has shown that hypothyroidism affects the cardiovascular system, significantly increasing the incidence of cardiovascular diseases. In the present study we investigated the effect of radioactive iodine (I-131)-induced hypothyroidism on several parameters of vascular function, such as nitric oxide (NO), total nitric oxide synthase (NOS) activity and expression of NOS isoforms, as well as on interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) as indicators of inflammation, in rats. A dose of 150 µCi of 131-I was determined as optimal for establishing the model of hypothyroidism in rats. After administration of 131-I, at the end of month 1, 2, and 4 (n = 3 for each time point), NO, IL-6, and TNF-α in the serum and total NOS activity in the aorta were determined in 150 µCi group, compared to controls. The mRNA and protein expression of endothelial, neuronal, and inducible NOS (eNOS, nNOS, and iNOS) in the rat aorta was also estimated, using quantitative reverse transcription polymerase chain reaction and Western blot, respectively. The levels of IL-6 and TNF-α increased in 150 µCi group; the results were significant at the end of month 2 and 4 for IL-6, and at all time points for TNF-α. The levels of NO decreased significantly at the end of month 2 and 4 in 150 µCi group. The total NOS activity increased significantly in 150 µCi group, at all three time points. Significant changes in the mRNA and protein expression of all three NOS isoforms were observed in 150 µCi group compared to controls. NO, IL-6, TNF-α levels and NOS activity and expression are altered in hypothyroid state, and the underlying mechanism should be further investigated.


2002 ◽  
Vol 70 (12) ◽  
pp. 7165-7168 ◽  
Author(s):  
Bruce W. Jarvis ◽  
Tajie H. Harris ◽  
Nilofer Qureshi ◽  
Gary A. Splitter

ABSTRACT The intracellular, gram-negative pathogen Brucella abortus establishes chronic infections in host macrophages while downregulating cytokines such as tumor necrosis factor alpha (TNF-α). When producing TNF-α, Brucella abortus rough lipopolysaccharide (LPS) activates the same mitogen-activated protein kinase signaling pathways (ERK and JNK) as Escherichia coli LPS, but Brucella LPS is a much less potent agonist.


2006 ◽  
Vol 74 (11) ◽  
pp. 6100-6107 ◽  
Author(s):  
Daniel Engel ◽  
Ulrich Dobrindt ◽  
André Tittel ◽  
Petra Peters ◽  
Juliane Maurer ◽  
...  

ABSTRACT The role of dendritic cells (DC) in urinary tract infections (UTI) is unknown. These cells contribute directly to the innate defense against various viral and bacterial infections. Here, we studied their role in UTI using an experimental model induced by transurethral instillation of the uropathogenic Escherichia coli (UPEC) strain 536 into C57BL/6 mice. While few DC were found in the uninfected bladder, many had been recruited after 24 h, mostly to the submucosa and uroepithelium. They expressed markers of activation and maturation and exhibited the CD11b+ F4/80+ CD8− Gr-1− myeloid subtype. Also, tumor necrosis factor alpha (TNF-α)- and inducible nitric oxide synthase (iNOS)-producing CD11bINT DC (Tip-DC) were detected, which recently were proposed to be critical in the defense against bacterial infections. However, Tip-DC-deficient CCR2−/− mice did not show reduced clearance of UPEC from the infected bladder. Moreover, clearance was also unimpaired in CD11c-DTR mice depleted of all DC by injection of diphtheria toxin. This may be explained by the abundance of granulocytes and of iNOS- and TNF-α-producing non-DC that were able to replace Tip-DC functionality. These findings demonstrate that some of the abundant DC recruited in UTI contributed innate immune effector functions, which were, however, dispensable in the microenvironment of the bladder.


2002 ◽  
Vol 22 (8) ◽  
pp. 2620-2631 ◽  
Author(s):  
Alla V. Tsytsykova ◽  
Anne E. Goldfeld

ABSTRACT We present evidence that the inducer-specific regulation of the human tumor necrosis factor alpha (TNF-α) gene in T cells involves the assembly of distinct higher-order transcription enhancer complexes (enhanceosomes), which is dependent upon inducer-specific helical phasing relationships between transcription factor binding sites. While ATF-2, c-Jun, and the coactivator proteins CBP/p300 play a central role in TNF-α gene activation stimulated by virus infection or intracellular calcium flux, different sets of activators including NFATp, Sp1, and Ets/Elk are recruited to a shared set of transcription factor binding sites depending upon the particular stimulus. Thus, these studies demonstrate that the inducer-specific assembly of unique enhanceosomes is a general mechanism by which a single gene is controlled in response to different extracellular stimuli.


2000 ◽  
Vol 20 (16) ◽  
pp. 6084-6094 ◽  
Author(s):  
Eunice Y. Tsai ◽  
James V. Falvo ◽  
Alla V. Tsytsykova ◽  
Amy K. Barczak ◽  
Andreas M. Reimold ◽  
...  

ABSTRACT The tumor necrosis factor alpha (TNF-α) gene is rapidly activated by lipopolysaccharide (LPS). Here, we show that extracellular signal-regulated kinase (ERK) kinase activity but not calcineurin phosphatase activity is required for LPS-stimulated TNF-α gene expression. In LPS-stimulated macrophages, the ERK substrates Ets and Elk-1 bind to the TNF-α promoter in vivo. Strikingly, Ets and Elk-1 bind to two TNF-α nuclear factor of activated T cells (NFAT)-binding sites, which are required for calcineurin and NFAT-dependent TNF-α gene expression in lymphocytes. The transcription factors ATF-2, c-jun, Egr-1, and Sp1 are also inducibly recruited to the TNF-α promoter in vivo, and the binding sites for each of these activators are required for LPS-stimulated TNF-α gene expression. Furthermore, assembly of the LPS-stimulated TNF-α enhancer complex is dependent upon the coactivator proteins CREB binding protein and p300. The finding that a distinct set of transcription factors associates with a fixed set of binding sites on the TNF-α promoter in response to LPS stimulation lends new insights into the mechanisms by which complex patterns of gene regulation are achieved.


2003 ◽  
Vol 23 (22) ◽  
pp. 8377-8385 ◽  
Author(s):  
Thomas H. Lee ◽  
Qiaojia Huang ◽  
Sarah Oikemus ◽  
Jennifer Shank ◽  
Juan-Jose Ventura ◽  
...  

ABSTRACT The cytokine tumor necrosis factor alpha (TNF-α) stimulates the NF-κB, SAPK/JNK, and p38 mitogen-activated protein (MAP) kinase pathways by recruiting RIP1 and TRAF2 proteins to the tumor necrosis factor receptor 1 (TNFR1). Genetic studies have revealed that RIP1 links the TNFR1 to the IκB kinase (IKK) complex, whereas TRAF2 couples the TNFR1 to the SAPK/JNK cascade. In transfection studies, RIP1 and TRAF2 stimulate p38 MAP kinase activation, and dominant-negative forms of RIP1 and TRAF2 inhibit TNF-α-induced p38 MAP kinase activation. We found TNF-α-induced p38 MAP kinase activation and interleukin-6 (IL-6) production impaired in rip1 −/− murine embryonic fibroblasts (MEF) but unaffected in traf2−/− MEF. Yet, both rip1 −/− and traf2 −/− MEF exhibit a normal p38 MAP kinase response to inducers of osmotic shock or IL-1α. Thus, RIP1 is a specific mediator of the p38 MAP kinase response to TNF-α. These studies suggest that TNF-α-induced activation of p38 MAP kinase and SAPK/JNK pathways bifurcate at the level of RIP1 and TRAF2. Moreover, endogenous RIP1 associates with the MAP kinase kinase kinase (MAP3K) MEKK3 in TNF-α-treated cells, and decreased TNF-α-induced p38 MAP kinase activation is observed in Mekk3 −/− cells. Taken together, these studies suggest a mechanism whereby RIP1 may mediate the p38 MAP kinase response to TNF-α, by recruiting the MAP3K MEKK3.


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