scholarly journals hnRNP K plays a protective role in TNF-α-induced apoptosis in podocytes

2018 ◽  
Vol 38 (3) ◽  
Author(s):  
Shili Zhao ◽  
Junxia Feng ◽  
Qi Wang ◽  
Lu Tian ◽  
Yunfang Zhang ◽  
...  

Apoptosis of podocytes contributes to proteinuria in many chronic kidney diseases. The cytokine, tumor necrosis factor-α (TNF-α) is thought to be involved in podocyte apoptosis, but the underlying mechanism is not understood. In our study, we established a model of TNF-α-induced apoptosis by isolating primary podocytes from mice. After exposing cells to TNF-α, we determined the expression levels of heterogeneous nuclear ribonucleoprotein K (hnRNP K) and cellular FLICE-inhibitory protein (c-FLIP) and the phosphorylation levels of glycogen synthase kinase β (GSK3β) and extracellular signal-regulated kinase (ERK). We then knocked down or overexpressed the levels of hnRNP K and observed its effects on the expressions of c-FLIP, caspase-8, caspase-3, and the phosphorylation of GSK3β and ERK. In addition, we examined the percentage of cells undergoing apoptosis and studied cell cycle distribution. We found that TNF-α induced apoptosis in podocytes and that the expressions of hnRNP K and c-FLIP were significantly decreased, whereas the phosphorylations of GSK3β and ERK were significantly increased. Both gene knockdown and overexpression of hnRPN K resulted in varied expressions/phosphorylations of c-FLIP, GSK3β, and ERK. Moreover, decreased hnRPN K expression contributed to increased levels of caspase-8 and capase-3, as well as an increase in cell apoptosis and G0/G1 arrest. In conclusion, down-regulated expression of hnRNP K by TNF-α resulted in a decrease in the expression of c-FLIP as well as increases in phosphorylated GSK3β, ERK, caspase-8, and caspase-3, and then critically contributed to the podocyte apoptosis.

Blood ◽  
2002 ◽  
Vol 99 (11) ◽  
pp. 4079-4086 ◽  
Author(s):  
Nicholas Mitsiades ◽  
Constantine S. Mitsiades ◽  
Vassiliki Poulaki ◽  
Dharminder Chauhan ◽  
Paul G. Richardson ◽  
...  

The transcription factor nuclear factor–κB (NF-κB) confers significant survival potential in a variety of tumors. Several established or novel anti–multiple myeloma (anti-MM) agents, such as dexamethasone, thalidomide, and proteasome inhibitors (PS-341), inhibit NF-κB activity as part of their diverse actions. However, studies to date have not delineated the effects of specific inhibition of NF-κB activity in MM. We therefore investigated the effect of SN50, a cell-permeable specific inhibitor of NF-κB nuclear translocation and activity, on MM cells. SN50 induced apoptosis in MM cell lines and patient cells; down-regulated expression of Bcl-2, A1, X-chromosome–linked inhibitor-of-apoptosis protein (XIAP), cellular inhibitor-of-apoptosis protein 1 (cIAP-1), cIAP-2, and survivin; up-regulated Bax; increased mitochondrial cytochromec release into the cytoplasm; and activated caspase-9 and caspase-3, but not caspase-8. We have previously demonstrated that tumor necrosis factor–α (TNF-α) is present locally in the bone marrow microenvironment and induces NF-κB–dependent up-regulation of adhesion molecules on both MM cells and bone marrow stromal cells, with resultant increased adhesion. In this study, TNF-α alone induced NF-κB nuclear translocation, cIAP-1 and cIAP-2 up-regulation, and MM cell proliferation; in contrast, SN50 pretreatment sensitized MM cells to TNF-α–induced apoptosis and cleavage of caspase-8 and caspase-3, similar to our previous finding of SN50-induced sensitization to apoptosis induced by the TNF-α family member TNF-related apoptosis-inducing ligand (TRAIL)/Apo2L. Moreover, SN50 inhibited TNF-α–induced expression of another NF-κB target gene, intercellular adhesion molecule–1. Although the p38 inhibitor PD169316 did not directly kill MM cells, it potentiated the apoptotic effect of SN50, suggesting an interaction between the p38 and NF-κB pathways. Our results therefore demonstrate that NF-κB activity in MM cells promotes tumor-cell survival and protects against apoptotic stimuli. These studies provide the framework for targeting NF-κB activity in novel biologically based therapies for MM.


2006 ◽  
Vol 291 (5) ◽  
pp. G820-G829 ◽  
Author(s):  
Mantej S. Bharhani ◽  
Rajka Borojevic ◽  
Shibesh Basak ◽  
Edwin Ho ◽  
Pengfei Zhou ◽  
...  

We have previously shown that the absence of Fas/Fas ligand significantly reduced tissue damage and intestinal epithelial cell (IEC) apoptosis in an in vivo model of T cell-mediated enteropathy. This enteropathy was more severe in IL-10-deficient mice, and this was associated with increased serum levels of IFN-γ and TNF-α and an increase in Fas expression on IECs. In this study, we investigated the potential of IL-10 to directly influence Fas expression and Fas-induced IEC apoptosis. Mouse intestinal epithelial cell lines MODE-K and IEC4.1 were cultured with IFN-γ, TNF-α, or anti-Fas monoclonal antibody (mAb) in the presence or absence of IL-10. Fas expression and apoptosis were determined by FACScan analysis of phycoerythrin-anti-Fas mAb staining and annexin V staining, respectively. Treatment with a combination of IFN-γ and TNF-α induced significant apoptosis. Anti-Fas mAb alone did not induce much apoptosis unless cells were pretreated with IFN-γ and TNF-α. These IECs constitutively expressed low levels of Fas, which significantly increased by preincubation of the cells with IFN-γ and TNF-α. Treatment with cytokine or cytokine plus anti-Fas mAb increased apoptosis, which correlated with a decreased Fas-associated death domain IL-1-converting enzyme-like inhibitory protein (FLIP) level, increased caspase-8 activity, and subsequently increased caspase-3 activity. IL-10 diminished both cytokine- and anti-Fas mAb-induced apoptosis, and this was correlated with decreased cytokine-induced Fas expression, increased FLIP, and decreased caspase-8 and caspase-3 activity. In conclusion, IL-10 modulated cytokine induction of Fas expression on IEC cell lines and regulated IEC susceptibility to TNF-α, IFN-γ, and Fas-mediated apoptosis. These findings suggest that IL-10 directly modulates IEC responses to T cell-mediated apoptotic signals.


Blood ◽  
2011 ◽  
Vol 117 (22) ◽  
pp. 5953-5962 ◽  
Author(s):  
Barbara Geering ◽  
Ursina Gurzeler ◽  
Elena Federzoni ◽  
Thomas Kaufmann ◽  
Hans-Uwe Simon

Abstract The most common form of neutrophil death is apoptosis. In the present study, we report surprising differences in the molecular mechanisms used for caspase activation between FAS/CD95-stimulated and TNF receptor 1 (TNFR1)–stimulated neutrophils. Whereas FAS-induced apoptosis was followed by caspase-8 activation and required Bid to initiate the mitochondrial amplification loop, TNF-α–induced apoptosis involved class IA PI3Ks, which were activated by MAPK p38. TNF-α–induced PI3K activation resulted in the generation of reactive oxygen species, which activated caspase-3, a mechanism that did not operate in neutrophils without active NADPH oxidase. We conclude that in neutrophils, proapoptotic pathways after TNFR1 stimulation are initiated by p38 and PI3K, but not by caspase-8, a finding that should be considered in anti-inflammatory drug-development strategies.


Blood ◽  
2003 ◽  
Vol 101 (4) ◽  
pp. 1324-1328 ◽  
Author(s):  
Ik-Joo Chung ◽  
Chunhua Dai ◽  
Sanford B. Krantz

Interferon γ (IFNγ) acts on human erythroid colony-forming cells (ECFCs) to up-regulate Fas, without a demonstrable change of Fas ligand (FasL) or Fas-associated DD-containing protein (FADD) expression and activates caspase-8 plus caspase-3, which produce apoptosis. Our previous data showed that stem cell factor (SCF) reduced the inhibitory effect of IFNγ on human ECFCs when both factors were present in the cultures. However, the mechanism by which SCF prevents IFNγ-induced apoptosis in ECFCs is unclear. In this study we used highly purified human ECFCs to investigate the mechanism of the effect of SCF on IFNγ-induced apoptosis. Because the binding of FasL to Fas is the first step of the apoptosis cascade and IFNγ strongly up-regulates Fas expression, we added FasL (50 ng/mL) to the cultures with IFNγ to accentuate the IFNγ-induced activation of caspase-8 and caspase-3 plus subsequent apoptosis. SCF (100 ng/mL) clearly inhibited the activation of caspase-8 and caspase-3 induced by IFNγ and/or FasL, and it also reduced apoptosis as measured by the terminal dUTP nick-end labeling (TUNEL) assay. SCF did not decrease the surface expression of Fas on the ECFCs. FADD-like interleukin 1 β (IL-1β)–converting enzyme (FLICE)–inhibitory protein (FLIP) has been reported to interact with FADD and/or caspase-8 at the death-inducing signaling complex (DISC) level following Fas stimulation and acts as a dominant-negative caspase-8. SCF increased FLIP mRNA and protein expression, concomitant with reduced apoptosis, whereas IFNγ and/or FasL did not change FLIP expression. Reduction of FLIP expression with antisense oligonucleotides decreased the capacity of SCF to inhibit IFNγ-induced apoptosis, demonstrating a definite role for FLIP in the SCF-induced protection of ECFCs from IFNγ-initiated apoptosis.


2019 ◽  
Vol 39 (4) ◽  
Author(s):  
Wei Su ◽  
Xiaojie Jiang ◽  
Mingyuan Chen ◽  
Maotuan Huang ◽  
Nanhong Tang ◽  
...  

Abstract Gallbladder cancer (GBC) is a demanding fatal disease with no ideal treatment for inoperable patients. Recent reports have determined TNF-α associated lymphatic metastasis in GBC, while its resistance to TNF-α-killing remains largely unexplored. In this assay, we first found cellular inhibitor of apoptosis (cIAP1) overexpressed in GBC tissues and the roles in promoting the proliferation and migration of GBC in vitro as its homology cIAP2 does. Then how GBC cell survives TNF-α toxicity and TNF-α-induced apoptosis first prevail as follows. The reduction in cIAP1 does not give rise to apoptosis even with the stimulation of TNF-α. Importantly, the loss of cIAP1 enhanced TNF-α/cycloheximide-induced apoptosis in higher activation statuses of Caspase-8, Caspase-3 without the induction of Complex Ⅱ. In response to TNF-α, the reduction in cIAP1 caused the suppression in nuclear factor-κB (NF-κB) pathway and inhibition of transcription of cell death regulator cellular FLICE-like Inhibitory Protein (c-FLIP) instead. To conclude, cIAP1 is an oncological protein abundant in GBC tissues, which enhances proliferation and immigration and blocks TNF-α from apoptosis through NF-κB pathway in vitro.


2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Tingting Meng ◽  
Ying Zhou ◽  
Jingkun Li ◽  
Meilin Hu ◽  
Xiaomeng Li ◽  
...  

Background and Objective. This study investigated the effects and underlying mechanisms of azithromycin (AZM) treatment on the osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) after their stimulation with TNF-α in vitro. Methods. PDLSCs were isolated from periodontal ligaments from extracted teeth, and MTS assay was used to evaluate whether AZM and TNF-α had toxic effects on PDLSCs viability and proliferation. After stimulating PDLSCs with TNF-α and AZM, we analyzed alkaline phosphatase staining, alkaline phosphatase activity, and alizarin red staining to detect osteogenic differentiation. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis was performed to detect the mRNA expression of osteogenic-related genes, including RUNX2, OCN, and BSP. Western blotting was used to measure the NF-κB signaling pathway proteins p65, phosphorylated p65, IκB-α, phosphorylated IκB-α, and β-catenin as well as the apoptosis-related proteins caspase-8 and caspase-3. Annexin V assay was used to detect PDLSCs apoptosis. Results. TNF-α stimulation of PDLSCs decreased alkaline phosphatase and alizarin red staining, alkaline phosphatase activity, and mRNA expression of RUNX2, OCN, and BSP in osteogenic-conditioned medium. AZM enhanced the osteogenic differentiation of PDLSCs that were stimulated with TNF-α. Western blot analysis showed that β-catenin, phosphorated p65, and phosphorylated IκB-α protein expression decreased in PDLSCs treated with AZM. In addition, pretreatment of PDLSCs with AZM (10 μg/ml, 20 μg/ml) prevented TNF-α-induced apoptosis by decreasing caspase-8 and caspase-3 expression. Conclusions. Our results showed that AZM promotes PDLSCs osteogenic differentiation in an inflammatory microenvironment by inhibiting the WNT and NF-κB signaling pathways and by suppressing TNF-α-induced apoptosis. This suggests that AZM has potential as a clinical therapeutic for periodontitis.


BMC Cancer ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Fanling Hong ◽  
Yujun Zhang ◽  
Wenjin Cheng ◽  
Xiuli Sun ◽  
Jianliu Wang

Abstract Background β-arrestin-2(Arr2) functions as an anti-apoptotic factor and affects cell proliferation, but its downstream molecular pathway in endometrial carcinoma (EC) is still unclear. This study aimed to investigate the effects of the stable overexpression of Arr2 on the proliferation and apoptosis of human EC heterotransplants and the expression of associated molecules, including Toll-like receptor 2(TLR2), serine-threonine kinase Akt (Akt), glycogen synthase kinase-3β(GSK3β) and some typical inflammatory cytokines such as NF-κB p56, TNF-α and IL-6 & IL-8. Methods Human EC cell line Ishikawa, stably transfected with Arr2 full-length plasmid, was injected subcutaneously into nude mice. They were treated with 0, 10, 20 mg/kg paclitaxel and the volume and weight of the tumor tissue were measured and calculated. The necrotic index were assessed by H&E staining and microscopic observation. The levels of caspase-3, caspase-9, TLR2, NF-κB p56, Akt, GSK3β were measured by western blot, and the levels of TNF-α, IL-6, IL-8 were measured by real-time PCR. Results We found that Arr2 overexpression promoted the growth of human EC heterotransplants. Arr2 attenuated the promotion of caspase-3 and caspase-9 by paclitaxel and mediated the increase of TLR2 and several inflammatory cytokines. The levels of Akt and GSK3β were not affected. Conclusion Arr2 overexpression was associated with the increase of TLR2 and several inflammatory factors, meanwhile inhibited paclitaxel-induced anti-tumor effect on human EC heterotransplants.


2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Yu Wang ◽  
Chunhui Xia ◽  
Wei Chen ◽  
Yuhang Chen ◽  
Yiyi Wang ◽  
...  

Photodynamic therapy (PDT) is a novel and promising antitumor treatment. Our previous study showed that hydrophilic/lipophilic tetra-α-(4-carboxyphenoxy) phthalocyanine zinc- (TαPcZn-) mediated PDT (TαPcZn-PDT) inhibits the proliferation of human hepatocellular carcinoma Bel-7402 cells by triggering apoptosis and arresting cell cycle. However, mechanisms of TαPcZn-PDT-induced apoptosis of Bel-7402 cells have not been fully clarified. In the present study, therefore, effect of TαPcZn-PDT on apoptosis, P38MAPK, p-P38MAPK, Caspase-8, Caspase-3, Bcl-2, Bid, Cytochrome c, and mitochondria membrane potential in Bel-7402 cells without or with P38MAPK inhibitor SB203580 or Caspase-8 inhibitor Ac-IEFD-CHO was investigated by haematoxylin and eosin (HE) staining assay, flow cytometry analysis of annexin V-FITC/propidium iodide (PI) double staining cells and 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolylcarbocyanine iodide (JC-1), and immunoblot assay. We found that TαPcZn-PDT resulted in apoptosis induction, activation of P38MAPK, Caspase-8, Caspase-3, and Bid, downregulation of Bcl-2, release of Cytochrome c from mitochondria, and disruption of mitochondrial membrane potential in TαPcZn-PDT-treated Bel-7402 cells. In contrast, SB203580 or Ac-IEFD-CHO attenuated induction of apoptosis, activation of P38MAPK, Caspase-8, Caspase-3, and Bid, downregulation of Bcl-2, release of Cytochrome c from mitochondria, and disruption of mitochondrial membrane potential in TαPcZn-PDT-treated Bel-7402 cells. Taken together, we conclude that Caspase-3, Bcl-2, Bid, and mitochondria are involved in autoregulatory feedback of P38MAPK/Caspase-8 during TαPcZn-PDT-induced apoptosis of Bel-7402 cells.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2177-2177
Author(s):  
Duncan H Mak ◽  
Christa Manton ◽  
Michael Andreeff ◽  
Bing Z Carter

Abstract Abstract 2177 The antiapoptotic function of the inhibitors of apoptosis family of proteins (IAPs) is antagonized by mitochondria-released SMAC protein. The IAP-member XIAP suppresses apoptosis by directly binding and inhibiting caspase-9 and caspase-3, while cIAP1, a component of the cytoplasmic signaling complex containing TNF receptor associated factors, suppresses apoptosis via the caspase-8-mediated pathway. BV-6 (Genentech) is a bivalent SMAC-mimetic and has been shown to promote cell death by inducing cIAP autoubiquitination, NF-κB activation, and TNFα-dependent apoptosis. We examined its effect on leukemic cells and found that BV-6 only moderately induced apoptosis. The EC50 was found to be 15.3±5.1 μM at 48 hours in OCI-AML3 cells which are relatively sensitive. We then determined whether BV-6 sensitizes leukemic cells to the HDM2-inhibitor nutlin-3a and to Ara-C. p53 modulates the expression and activity of Bcl-2 family proteins and promotes the mitochondrial-mediated apoptosis. We showed previously that activation of p53 by nutlin-3a sensitizes AML cells to XIAP inhibition induced-death in part by promoting the release of SMAC from mitochondrion (Carter BZ et al., Blood 2010). We treated OCI-AML3 cells with BV-6, nutlin-3a or Ara-C, and BV-6+nutlin-3a or BV-6+Ara-C and found that the combination of BV-6 and nutlin-3a or BV-6 and Ara-C synergistically induced cell death in OCI-AML3 cells with a combination index (CI) of 0.27±0.11 and 0.22±0.05 (48 hours), respectively. To demonstrate that p53 activation is essential for the synergism of BV-6+nutlin-3a combination, we treated OCI-AML3 vector control and p53 knockdown cells with these two agents and found that the combination synergistically promoted cell death in the vector control (CI=0.47±0.15) but not in the p53 knockdown cells, as expected, while BV6+Ara-C was synergistic in both vector control and p53 knockdown cells (CI=0.15±0.03 and 0.08±0.03, respectively, 48 hours). BV-6 induced activation of caspase-8, caspase-9, and caspase-3 and decreased XIAP levels, but did not cause rapid cIAP1 degradation, as reported by others. To assess the contribution of death receptor-mediated apoptosis in BV-6-induced cell death, we treated Jurkat and caspase-8 mutated Jurkat cells (JurkatI9.2) with BV-6 and found that BV-6 induced cell death and significantly potentiated TRAIL-induced apoptosis in Jurkat cells (CI=0.14±0.08, 48 hours). Caspase-8 mutated JurkatI9.2 cells were significantly less sensitive to BV-6 than Jurkat cells and as expected, JurkatI9.2 was completely resistant to TRAIL. Collectively, we showed that the bivalent SMAC-mimetic BV-6 potentiates p53 activation-, chemotherapy-, and TRAIL-induced cell death, but has only minimal activity by itself in leukemic cells. SMAC-mimetics could be useful in enhancing the efficacy of different classes of therapeutic agents used in AML therapy. Disclosures: No relevant conflicts of interest to declare.


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