scholarly journals PP2Acα promotes macrophage accumulation and activation to exacerbate tubular cell death and kidney fibrosis through activating Rap1 and TNFα production

2021 ◽  
Author(s):  
Yan Liang ◽  
Xiaoli Sun ◽  
Mingjie Wang ◽  
Qingmiao Lu ◽  
Mengru Gu ◽  
...  
Keyword(s):  
Cell Death ◽  
Tubular Cell ◽  
Kidney Fibrosis ◽  
Tubular Cells ◽  
Ureter Obstruction ◽  
Underlying Mechanisms ◽  
Factor Α ◽  
Rap1 Activation ◽  
Necrosis Factor ◽  
Macrophage Accumulation

AbstractMacrophage accumulation and activation play an essential role in kidney fibrosis; however, the underlying mechanisms remain to be explored. By analyzing the kidney tissues from patients and animal models with kidney fibrosis, we found a large induction of PP2Acα in macrophages. We then generated a mouse model with inducible macrophage ablation of PP2Acα. The knockouts developed less renal fibrosis, macrophage accumulation, or tubular cell death after unilateral ureter obstruction or ischemic reperfusion injury compared to control littermates. In cultured macrophages, PP2Acα deficiency resulted in decreased cell motility by inhibiting Rap1 activity. Moreover, co-culture of PP2Acα−/− macrophages with tubular cells resulted in less tubular cell death attributed to downregulated Stat6-mediated tumor necrosis factor α (TNFα) production in macrophages. Together, this study demonstrates that PP2Acα promotes macrophage accumulation and activation, hence accelerates tubular cell death and kidney fibrosis through regulating Rap1 activation and TNFα production.

scholarly journals Tumor Necrosis Factor-α Increases ATP Content in Metabolically Inhibited L929 Cells Preceding Cell Death

1997 ◽  
Vol 272 (48) ◽  
pp. 30167-30177 ◽  
Author(s):  
José A. Sánchez-Alcázar ◽  
Jesús Ruı́z-Cabello ◽  
Inmaculada Hernández-Muñoz ◽  
Pilar Sánchez Pobre ◽  
Paz de la Torre ◽  
...  
Keyword(s):  
Cell Death ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Atp Content ◽  
L929 Cells ◽  
Factor Α ◽  
Necrosis Factor ◽  
Preceding Cell

Increased cytochrome P-450 2E1 expression sensitizes hepatocytes to c-Jun-mediated cell death from TNF-α

2002 ◽  
Vol 282 (2) ◽  
pp. G257-G266 ◽  
Author(s):  
Hailing Liu ◽  
Brett E. Jones ◽  
Cynthia Bradham ◽  
Mark J. Czaja
Keyword(s):  
Cell Death ◽  
Oxidant Stress ◽  
Nuclear Factor Κb ◽  
Dominant Negative ◽  
Tnf Α ◽  
Cyp2e1 Expression ◽  
Factor Α ◽  
Jnk Activation ◽  
Cytochrome P 450 ◽  
Necrosis Factor

The mechanisms underlying hepatocyte sensitization to tumor necrosis factor-α (TNF-α)-mediated cell death remain unclear. Increases in hepatocellular oxidant stress such as those that occur with hepatic overexpression of cytochrome P-450 2E1 (CYP2E1) may promote TNF-α death. TNF-α treatment of hepatocyte cell lines with differential CYP2E1 expression demonstrated that overexpression of CYP2E1 converted the hepatocyte TNF-α response from proliferation to apoptotic and necrotic cell death. Death occurred despite the presence of increased levels of nuclear factor-κB transcriptional activity and was associated with increased lipid peroxidation and GSH depletion. CYP2E1-overexpressing hepatocytes had increased basal and TNF-α-induced levels of c-Jun NH2-terminal kinase (JNK) activity, as well as prolonged JNK activation after TNF-α stimulation. Sensitization to TNF-α-induced cell death by CYP2E1 overexpression was inhibited by antioxidants or adenoviral expression of a dominant-negative c-Jun. Increased CYP2E1 expression sensitized hepatocytes to TNF-α toxicity mediated by c-Jun and overwhelming oxidative stress. The chronic increase in intracellular oxidant stress created by CYP2E1 overexpression may serve as a mechanism by which hepatocytes are sensitized to TNF-α toxicity in liver disease.

scholarly journals Yersinia enterocolitica Impairs Activation of Transcription Factor NF-κB: Involvement in the Induction of Programmed Cell Death and in the Suppression of the Macrophage Tumor Necrosis Factor α Production

1998 ◽  
Vol 187 (7) ◽  
pp. 1069-1079 ◽  
Author(s):  
Klaus Ruckdeschel ◽  
Suzanne Harb ◽  
Andreas Roggenkamp ◽  
Mathias Hornef ◽  
Robert Zumbihl ◽  
...  
Keyword(s):  
Cell Death ◽  
Transcription Factor ◽  
Tumor Necrosis Factor ◽  
Programmed Cell Death ◽  
Proteasome Inhibitor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Tnf Α ◽  
Factor Α ◽  
Necrosis Factor

In this study, we investigated the activity of transcription factor NF-κB in macrophages infected with Yersinia enterocolitica. Although triggering initially a weak NF-κB signal, Y. enterocolitica inhibited NF-κB activation in murine J774A.1 and peritoneal macrophages within 60 to 90 min. Simultaneously, Y. enterocolitica prevented prolonged degradation of the inhibitory proteins IκB-α and IκB-β observed by treatment with lipopolysaccharide (LPS) or nonvirulent, plasmid-cured yersiniae. Analysis of different Y. enterocolitica mutants revealed a striking correlation between the abilities of these strains to inhibit NF-κB and to suppress the tumor necrosis factor α (TNF-α) production as well as to trigger macrophage apoptosis. When NF-κB activation was prevented by the proteasome inhibitor MG-132, nonvirulent yersiniae as well as LPS became able to trigger J774A.1 cell apoptosis and inhibition of the TNF-α secretion. Y. enterocolitica also impaired the activity of NF-κB in epithelial HeLa cells. Although neither Y. enterocolitica nor TNF-α could induce HeLa cell apoptosis alone, TNF-α provoked apoptosis when activation of NF-κB was inhibited by Yersinia infection or by the proteasome inhibitor MG-132. Together, these data demonstrate that Y. enterocolitica suppresses cellular activation of NF-κB, which inhibits TNF-α release and triggers apoptosis in macrophages. Our results also suggest that Yersinia infection confers susceptibility to programmed cell death to other cell types, provided that the appropriate death signal is delivered.

scholarly journals Tumor necrosis factor-α suppresses angiotensinogen expression through formation of a p50/p50 homodimer in human renal proximal tubular cells

2010 ◽  
Vol 299 (4) ◽  
pp. C750-C759 ◽  
Author(s):  
Ryousuke Satou ◽  
Kayoko Miyata ◽  
Akemi Katsurada ◽  
L. Gabriel Navar ◽  
Hiroyuki Kobori
Keyword(s):  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Proximal Tubular Cells ◽  
Tubular Cells ◽  
Tnf Α ◽  
Proximal Tubular ◽  
Renal Proximal Tubular Cells ◽  
Renal Proximal Tubular ◽  
Factor Α ◽  
Necrosis Factor

Angiotensinogen (AGT) expression in renal proximal tubular cells (RPTCs) and intrarenal tumor necrosis factor-α (TNF-α) levels are increased in hypertension and renal diseases However, the contribution of TNF-α to AGT expression in RPTCs has not been established. Therefore, the objective of the present study was to determine influence of TNF-α on AGT expression in RPTCs. Human kidney-2 (HK-2) cells, immortalized human RPTCs, were treated with several concentrations of TNF-α up to 24 h. AGT mRNA and protein expression were evaluated by RT-PCR and ELISA, respectively. Activation of nuclear factor-κB (NF-κB) by TNF-α was evaluated by Western blot analysis, immunocytochemistry, and electrophoretic mobility shift assay (EMSA). TNF-α suppressed AGT mRNA expression in a dose- and time-dependent manner. Maximum AGT mRNA reduction was caused by 40 ng/ml of TNF-α (0.52 ± 0.09, ratio to control, at 24 h) and at 24 h (0.66 ± 0.05, ratio to control, by 10 ng/ml TNF-α). TNF-α reduced AGT protein accumulation in the medium between 8 and 24 h (0.62 ± 0.13 by 40 ng/ml TNF-α, ratio to control). TNF-α activated and induced translocalization of p50 and p65, which are NF-κB subunits. Elevated formation of p50/p65 and p50/p50 dimers by TNF-α were observed by EMSA and supershift assay. Gene silencing of p50, but not p65, attenuated the effect of TNF-α on reduction of AGT expression in RPTCs. These results indicate that TNF-α suppresses AGT expression through p50/p50 homodimer formation in human RPTCs, suggesting a possible counteracting mechanism that limits excessive intrarenal AGT production.

Tumor necrosis factor-α and ceramide induce cell death through different mechanisms in rat mesangial cells

1999 ◽  
Vol 276 (3) ◽  
pp. F390-F397 ◽  
Author(s):  
Yan-Lin Guo ◽  
Baobin Kang ◽  
Li-Jun Yang ◽  
John R. Williamson
Keyword(s):  
Cell Death ◽  
Protein Kinase ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Mesangial Cells ◽  
Tnf Α ◽  
Induced Apoptosis ◽  
Factor Α ◽  
Necrosis Factor

It has been proposed that ceramide acts as a cellular messenger to mediate tumor necrosis factor-α (TNF-α)-induced apoptosis. Based on this hypothesis, it was postulated that resistance of some cells to TNF-α cytotoxicity was due to an insufficient production of ceramide on stimulation by TNF-α. The present study was initiated to investigate whether this was the case in mesangial cells, which normally are insensitive to TNF-α-induced apoptosis. Our results indicate that although C2ceramide was toxic to mesangial cells, the cell death it induced differed both morphologically and biochemically from that induced by TNF-α in the presence of cycloheximide (CHX). The most apparent effect of C2ceramide was to cause cells to swell, followed by disruption of the cell membrane. It is evident that C2ceramide caused cell death by necrosis, whereas TNF-α in the presence of CHX killed the cells by apoptosis. C2ceramide did not mimic the effects of TNF-α on the activation of c-Jun NH2-terminal protein kinase and nuclear factor-κB transcription factor. Although mitogen-activated protein kinase [extracellular signal-related kinase (ERK)] was activated by both C2ceramide and TNF-α, such activation appeared to be mediated by different mechanisms as judged from the kinetics of ERK activation. Furthermore, the cleavage of cytosolic phospholipase A2during cell death induced by C2ceramide and by TNF-α in the presence of CHX showed distinctive patterns. The present study provides evidence that apoptosis and necrosis use distinctive signaling machinery to cause cell death.

scholarly journals Tumor-Induced Oxidative Stress Perturbs Nuclear Factor-κB Activity-Augmenting Tumor Necrosis Factor-α–Mediated T-Cell Death: Protection by Curcumin

2007 ◽  
Vol 67 (1) ◽  
pp. 362-370 ◽  
Author(s):  
Sankar Bhattacharyya ◽  
Debaprasad Mandal ◽  
Gouri Sankar Sen ◽  
Suman Pal ◽  
Shuvomoy Banerjee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Death ◽  
T Cell ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Nuclear Factor Κb ◽  
Nuclear Factor ◽  
Factor Α ◽  
Necrosis Factor
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