scholarly journals p38 Mitogen-Activated Protein Kinase Mediates Lipopolysaccharide and Tumor Necrosis Factor Alpha Induction of Shiga Toxin 2 Sensitivity in Human Umbilical Vein Endothelial Cells

2007 ◽  
Vol 76 (3) ◽  
pp. 1115-1121 ◽  
Author(s):  
Matthew K. Stone ◽  
Glynis L. Kolling ◽  
Matthew H. Lindner ◽  
Tom G. Obrig

ABSTRACTEscherichia coliO157:H7 Shiga toxin 2 (Stx2), one of the causative agents of hemolytic-uremic syndrome, is toxic to endothelial cells, including primary cultured human umbilical vein endothelial cells (HUVEC). This sensitivity of cells to Stx2 can be increased with either lipopolysaccharide (LPS) or tumor necrosis factor alpha (TNF-α). The goal of the present study was to identify the intracellular signaling pathway(s) by which LPS and TNF-α sensitize HUVEC to the cytotoxic effects of Stx2. To identify these pathways, specific pharmacological inhibitors and small interfering RNAs were tested with cell viability endpoints. A time course and dose response experiment for HUVEC exposure to LPS and TNF-α showed that a relatively short exposure to either agonist was sufficient to sensitize the cells to Stx2 and that both agonists stimulated intracellular signaling pathways within a short time. Cell viability assays indicated that the p38 mitogen-activated protein kinase (MAPK) inhibitors SB202190 and SB203580 and the general protein synthesis inhibitor cycloheximide inhibited both the LPS and TNF-α sensitization of HUVEC to Stx2, while all other inhibitors tested did not inhibit this sensitization. Additionally, SB202190 reduced the cellular globotriaosylceramide content under LPS- and TNF-α-induced conditions. In conclusion, our results show that LPS and TNF-α induction of Stx2 sensitivity in HUVEC is mediated through a pathway that includes p38 MAPK. These results indicate that inhibition of p38 MAPK in endothelial cells may protect a host from the deleterious effects of Stx2.

Blood ◽  
2005 ◽  
Vol 106 (10) ◽  
pp. 3423-3431 ◽  
Author(s):  
Ahmad Salameh ◽  
Federico Galvagni ◽  
Monia Bardelli ◽  
Federico Bussolino ◽  
Salvatore Oliviero

AbstractVascular endothelial growth factor receptor-3 (VEGFR-3) plays a key role for the remodeling of the primary capillary plexus in the embryo and contributes to angiogenesis and lymphangiogenesis in the adult. However, VEGFR-3 signal transduction pathways remain to be elucidated. Here we investigated VEGFR-3 signaling in primary human umbilical vein endothelial cells (HUVECs) by the systematic mutation of the tyrosine residues potentially involved in VEGFR-3 signaling and identified the tyrosines critical for its function. Y1068 was shown to be essential for the kinase activity of the receptor. Y1063 signals the receptor-mediated survival by recruiting CRKI/II to the activated receptor, inducing a signaling cascade that, via mitogen-activated protein kinase kinase-4 (MKK4), activates c-Jun N-terminal kinase-1/2 (JNK1/2). Inhibition of JNK1/2 function either by specific peptide inhibitor JNKI1 or by RNA interference (RNAi) demonstrated that activation of JNK1/2 is required for a VEGFR-3–dependent prosurvival signaling. Y1230/Y1231 contributes, together with Y1337, to proliferation, migration, and survival of endothelial cells. Phospho-Y1230/Y1231 directly recruits growth factor receptor–bonus protein (GRB2) to the receptor, inducing the activation of both AKT and extracellular signal–related kinase 1/2 (ERK1/2) signaling. Finally, we observed that Y1063 and Y1230/Y1231 signaling converge to induce c-JUN expression, and RNAi experiments demonstrated that c-JUN is required for growth factor–induced prosurvival signaling in primary endothelial cells.


2001 ◽  
Vol 69 (3) ◽  
pp. 1273-1279 ◽  
Author(s):  
Hubertus P. A. Jersmann ◽  
Charles S. T. Hii ◽  
Judith V. Ferrante ◽  
Antonio Ferrante

ABSTRACT One of the recognized associations of bacterial infection with cardiovascular events is the activation of endothelium and upregulation of adhesion molecules. The two major proinflammatory mediators implicated in the causation of cardiovascular events, bacterial lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF), were found to cooperate to enhance the adhesive properties of endothelial cells. These caused synergistic upregulation of intercellular adhesion molecule-1, E-selectin, and vascular cell adhesion molecule-1 in human umbilical vein endothelial cells as determined by flow cytometry analysis and enzyme-linked immunosorbent assay. This synergism was not due to TNF causing an upregulation of CD14 expression. Treatment with both LPS and TNF resulted in a marked increase in the translocation of NF-κB into the nucleus. The activity of p38 mitogen-activated protein kinase was also synergistically enhanced, while the activity of c-jun N-terminal kinase was increased in an additive manner. The results demonstrate that LPS and TNF act synergistically to upregulate the expression of endothelial cell adhesion molecules, possibly by amplification of signaling pathways upstream of transcription. These findings have implications for the understanding of the acceleration of atherosclerotic events seen in low-grade infections with gram-negative organisms.


2017 ◽  
Vol 49 (7) ◽  
pp. 339-345 ◽  
Author(s):  
Tse-Shun Huang ◽  
Kuei-Chun Wang ◽  
Sara Quon ◽  
Phu Nguyen ◽  
Ting-Yu Chang ◽  
...  

The long noncoding RNAs (lncRNAs), which constitute a large portion of the transcriptome, have gained intense research interest because of their roles in regulating physiological and pathophysiological functions in the cell. We identified from RNA-Seq profiling a set of lncRNAs in cultured human umbilical vein endothelial cells (HUVECs) that are differentially regulated by atheroprotective vs. atheroprone shear flows. Among the comprehensively annotated lncRNAs, including both known and novel transcripts, LINC00341 is one of the most abundant lncRNAs in endothelial cells. Moreover, its expression level is enhanced by atheroprotective pulsatile shear flow and atorvastatin. Overexpression of LINC00341 suppresses the expression of vascular cell adhesion molecule 1 (VCAM1) and the adhesion of monocytes induced by atheroprone flow and tumor necrosis factor-alpha. Underlying this anti-inflammatory role, LINC00341 guides enhancer of zest homolog 2, a core histone methyltransferase of polycomb repressive complex 2, to the promoter region of the VCAM1 gene to suppress VCAM1. Network analysis reveals that the key signaling pathways (e.g., Rho and PI3K/AKT) are co-regulated with LINC00341 in endothelial cells in response to pulsatile shear. Together, these findings suggest that LINC00341, as an example of lncRNAs, plays important roles in modulating endothelial function in health and disease.


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.


2012 ◽  
Vol 80 (7) ◽  
pp. 2570-2576 ◽  
Author(s):  
Toshinori Komatsu ◽  
Keiji Nagano ◽  
Shinsuke Sugiura ◽  
Makoto Hagiwara ◽  
Naomi Tanigawa ◽  
...  

ABSTRACTPorphyromonas gingivalis, a major periodontal pathogen, may contribute to atherogenesis and other inflammatory cardiovascular diseases. However, little is known about interactions betweenP. gingivalisand endothelial cells. E-selectin is a membrane protein on endothelial cells that initiates recruitment of leukocytes to inflamed tissue, and it may also play a role in pathogen attachment. In the present study, we examined the role of E-selectin inP. gingivalisadherence to endothelial cells. Human umbilical vein endothelial cells (HUVECs) were stimulated with tumor necrosis factor alpha (TNF-α) to induce E-selectin expression. Adherence ofP. gingivalisto HUVECs was measured by fluorescence microscopy. TNF-α increased adherence of wild-typeP. gingivalisto HUVECs. Antibodies to E-selectin and sialyl Lewis X suppressedP. gingivalisadherence to stimulated HUVECs.P. gingivalismutants lacking OmpA-like proteins Pgm6 and -7 had reduced adherence to stimulated HUVECs, but fimbria-deficient mutants were not affected. E-selectin-mediatedP. gingivalisadherence activated endothelial exocytosis. These results suggest that the interaction between host E-selectin and pathogen Pgm6/7 mediatesP. gingivalisadherence to endothelial cells and may trigger vascular inflammation.


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.


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