Abstract A13: Selective role of iNOS reveals its negative regulatory influence on the expression of TNFR1, NF-κB and other cell survival signaling events during a P19-induced apoptosis in HL-60 cells

2010 ◽  
Author(s):  
Fayaz Malik
Keyword(s):  
Cell Survival ◽  
Regulatory Influence ◽  
Signaling Events ◽  
Survival Signaling ◽  
Induced Apoptosis

scholarly journals Dengue activates mTORC2 signaling to counteract apoptosis and maximize viral replication

2020 ◽  
Author(s):  
Christoph C. Carter ◽  
Jean Paul Olivier ◽  
Alexis Kaushansky ◽  
Fred D. Mast ◽  
John D. Aitchison
Keyword(s):  
Viral Replication ◽  
Cell Survival ◽  
Structural Protein ◽  
Protein Protein Interaction ◽  
Mechanistic Target Of Rapamycin ◽  
Promote Cell Survival ◽  
Important Regulator ◽  
Infected Cells ◽  
Induced Apoptosis

ABSTRACTThe mechanistic target of rapamycin (mTOR) functions in at least two distinct complexes: mTORC1, which regulates cellular anabolic-catabolic homeostasis, and mTORC2, which is an important regulator of cell survival and cytoskeletal maintenance. mTORC1 has been implicated in the pathogenesis of flaviviruses including dengue, where it contributes to the establishment of a pro-viral autophagic state. In contrast, the role of mTORC2 in viral pathogenesis is unknown. In this study, we explore the consequences of a physical protein-protein interaction between dengue non-structural protein 5 (NS5) and host cell mTOR proteins during infection. Using shRNA to differentially target mTORC1 and mTORC2 complexes, we show that mTORC2 is required for optimal dengue replication. Furthermore, we show that mTORC2 is activated during viral replication, and that mTORC2 counteracts virus-induced apoptosis, promoting the survival of infected cells. This work reveals a novel mechanism by which the dengue flavivirus can promote cell survival to maximize viral replication.

The Regulation of STAT3 and Its Role in the Adhesion and Migration of Chronic Lymphocytic Leukaemia Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 4347-4347
Author(s):  
Sarah Brophy ◽  
Fiona M Quinn ◽  
David O'Brien ◽  
Paul Browne ◽  
Elisabeth A. Vandenberghe ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Cell Adhesion ◽  
Cell Survival ◽  
Lymphocytic Leukaemia ◽  
Serine Phosphorylation ◽  
Pre Treatment ◽  
And Migration ◽  
Induced Apoptosis ◽  
Stat3 Inhibition

Abstract The bone marrow and lymph node microenvironments are important in promoting cell proliferation, survival and protection from drug induced apoptosis in chronic lymphocytic leukaemia (CLL). Chemokine networks, such as the CXCR4/CXCL12 axis, in combination with selectins, such as CD62L and integrins allow the migration of CLL cells to these protective niches. The B-cell receptor (BCR) signalling pathway is the most important pathway involved in micro-environmental crosstalk and CLL cell survival. Further, it has been shown to interact with the signal transducer and activator of transcription 3 (STAT3) signalling pathway. The role of the STAT3 in CLL pathogenesis is unclear; however, it is constitutively phosphorylated on serine residue 727 (serine pSTAT3) in CLL cells. Here, we investigate the role of STAT3 in CLL cell survival and migration, using pharmacological inhibition and siRNA knockdown. Phospho-tyrosine and phospho-serine STAT3 were assessed by flow cytometry and western blotting. Apoptosis was assessed by Annexin V/Propidium Iodide staining by flow cytometry. The expression of cell surface markers involved in cell adhesion and homing was determined by multicolour flow cytometry. Stimulation of the BCR using immunoglobulin F(ab´)2 fragments induced tyrosine phosphorylation of STAT3 in CLL cells with unmutated immunoglobulin (IgVH) genes (n=7) but not mutated IgVH genes (n=5). This induced tyrosine phosphorylation was abrogated by pre-treatment with the Janus kinase (JAK) inhibitor Ruxolitinib and the BCR inhibitors Ibrutinib and Idelalisib (p<0.05, n=5). Gene expression studies using Taqman Assays showed BCR stimulation resulted in an upregulation of STAT3 regulated genes in CLL cells with unmutated IgVH genes. Interestingly, stimulation of BCR resulted in a significant increase in CD62L expression, which was inhibited by pre-treatment with Ibrutinib and Ruxolitinib (p<0.05, n=5). STAT3 inhibition was shown to have a divergent effect on CLL cell survival: In patient samples with >70% positive serine pSTAT3 cells, the STAT3 inhibitor cucurbitacin I induced apoptosis with a concurrent downregulation in serine phosphorylation (n=3); while in patient samples with <70% positive serine pSTAT3 cells, treatment with cucurbitacin I resulted in a decrease in apoptosis and a concurrent increase in serine phosphorylation (n=3). The STAT3 inhibitor S3I-201 had a similar effect but the upstream JAK inhibitor Ruxolitinib had no effect on serine phosphorylation and no effect on the apoptosis of CLL cells. In addition, siRNA mediated STAT3 knockdown and treatment with cucurbitacin I and S31-201, resulted in a significant decrease in CD62L positive CLL cells (p<0.0001, n=29). The role of STAT3 in CLL cell adhesion under shear flow conditions was investigated using a microfluidics system including a neMESYS Low Pressure syringe pump system and Human Umbilical Vein Endothelial Cells (HUVEC) coated biochips. Treatment of CLL cells with cucurbitacin I resulted in a significant decrease in adhesion to endothelial cells (p<0.001, n=4). The effect of STAT3 inhibition on the chemotaxis of CLL cells was investigated using Neuroprobe 96-well ChemoTx plates. Treatment with cucurbitacin I resulted in a significant decrease in CLL cells migrated in response to the chemokine CXCL12 compared to control (p=0.0001, n=8). In addition, treatment of CLL cells with CXCL12 resulted in an increase in serine pSTAT3 that was downregulated by pretreatment with cucurbitacin I. This study has shown: 1. Activation of STAT3 by BCR stimulation occurs in poor prognostic unmutated IgVH genes 2. Serine pSTAT3 has a role in cell survival in response to STAT3 inhibition 3. A role for STAT3 in CLL cell adhesion and migration, in particular in the regulation of the expression of CD62L. In conclusion, this study shows a role for the STAT3 pathway in cell survival and CLL cell-microenvironment crosstalk, suggesting therapeutic potential by interfering with the migration and homing of CLL cells to the lymph node and bone marrow microenvironments. Disclosures No relevant conflicts of interest to declare.

The role of the glucocorticoid receptor (GR) in inhibiting chemotherapy-induced apoptosis in high-grade serous ovarian carcinoma (HGS-OvCa).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 11101-11101
Author(s):  
Erica Michelle Stringer ◽  
Maxwell N. Skor ◽  
Gini F. Fleming ◽  
Suzanne D. Conzen
Keyword(s):  
Ovarian Cancer ◽  
Glucocorticoid Receptor ◽  
Tumor Cell ◽  
Cell Survival ◽  
Cell Lines ◽  
High Grade ◽  
Induced Apoptosis ◽  
Er Alpha ◽  
Ovca Cell

11101 Background: Ovarian cancer is the leading cause of death from gynecologic malignancies. High-grade serous ovarian cancer (HGS-OvCa) is often initially sensitive to platinum-based therapy, but relapse rates remain high. The TCGA recently found that HGS-OvCas have a gene expression and mutational profile similar to that of triple negative breast cancer (TNBC). Previously, our group demonstrated that dexamethasone treatment decreased chemotherapy-induced tumor cell apoptosis in TNBC and HGS-OvCa cell lines. We have also shown that glucocorticoid receptor (GR) activation induces expression of anti-apoptotic genes SGK1 and MKP1/DUSP1 in both HGS-OvCa and TNBC cell lines and in primary human ovarian and TNBC tumors. Methods: We examined glucocorticoid receptor (GR), estrogen receptor (ER), and progesterone receptor (PR) expression in a panel of HGS-OvCa cell lines by Western analysis and qRT-PCR. We also performed apoptosis assays with and without mifepristone, glucocorticoid and/or chemotherapy treatment using IncuCyte live-cell imaging technology in order to measure the effect of GR modulation of chemotherapy sensitivity. Results: HGS-OvCa cell lines (including CAOV3, HeyA8, SKOV3, Monty-1) all had detectable GR expression; HeyA8, SKOV3, and Monty-1 cell lines expressed very low levels of ER-alpha while all other HGS-OvCa cell lines did not express any detectable ER-alpha. Furthermore, none of the HGS-OvCa cell lines tested expressed PR.Apoptosis assays revealed that GR activation significantly inhibited gemcitabine/carboplatin-induced apoptosis in HGS-OvCa cell lines and that mifepristone could reverse this cell survival effect, presumably through GR antagonism. Conclusions: These results suggest that treatment with mifepristone, a GR antagonist, reverses GR-mediated cell survival signaling in HGS-OvCa and increases chemotherapy-induced tumor cell death. To further investigate the role of GR activity in HGS-OvCa, we are currently performing xenograft experiments with chemotherapy +/- mifepristone treatment.

scholarly journals Maintaining proton homeostasis is an essential role of glucose metabolism in cell survival

2016 ◽  
Author(s):  
Yanfen Cui ◽  
Yuanyuan Wang ◽  
Pan Xing ◽  
Li Qiu ◽  
Miao Liu ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Cell Survival ◽  
Aerobic Glycolysis ◽  
Critical Role ◽  
Glucose Deprivation ◽  
Proliferating Cells ◽  
Cellular Apoptosis ◽  
Induced Apoptosis ◽  
Apoptosis And Necrosis

AbstractAerobic glycolysis, termed “the Warburg Effect”, supports cell proliferation, and glucose deprivation directly elicits necrosis or shifts stimuli-induced apoptosis to necrosis. However, how glucose metabolism regulates cell survival or death choice remains largely unclear. Here we use our recently developed method to monitor in real-time cellular apoptosis and necrosis, and uncover a metabolic homeostasis linked to cell death control. We show that glucose metabolism is the major source to maintain both intracellular and extracellular proton homeostasis. Glucose deficiency leads to lack of proton provision, which provokes a compensatory lysosomal proton efflux and resultant increased lysosomal pH. This lysosomal alkalinization can trigger necrosis. Furthermore, artificial proton supplement enables cells to survive glucose deprivation. Taken together, our results reveal a critical role of glucose metabolism in maintaining cellular microenvironment, and provide a better understanding of the essential requirement of aerobic glycolysis for proliferating cells whose active anabolism consumes a great many protons.

scholarly journals The Dual Role of Calcium as Messenger and Stressor in Cell Damage, Death, and Survival

2010 ◽  
Vol 2010 ◽  
pp. 1-14 ◽  
Author(s):  
Claudia Cerella ◽  
Marc Diederich ◽  
Lina Ghibelli
Keyword(s):  
Cell Survival ◽  
Cell Damage ◽  
Second Messenger ◽  
Dual Role ◽  
Cell Stress ◽  
The Other ◽  
Signaling Events ◽  
The One

is an important second messenger participating in many cellular activities; when physicochemical insults deregulate its delicate homeostasis, it acts as an intrinsic stressor, producing/increasing cell damage. Damage elicits both repair and death responses; intriguingly, in those responses also participates as second messenger. This delineates a dual role for in cell stress, making difficult to separate the different and multiple mechanisms required for -mediated control of cell survival and apoptosis. Here we attempt to disentangle the two scenarios, examining on the one side, the events implicated in deregulated toxicity and the mechanisms through which this elicits reparative or death pathways; on the other, reviewing the role of as a messenger in the transduction of these same signaling events.

scholarly journals Bcl-3 Expression Promotes Cell Survival following Interleukin-4 Deprivation and Is Controlled by AP1 and AP1-Like Transcription Factors

2000 ◽  
Vol 20 (10) ◽  
pp. 3407-3416 ◽  
Author(s):  
Angelita Rebollo ◽  
Laure Dumoutier ◽  
Jean-Christophe Renauld ◽  
Angel Zaballos ◽  
Verónica Ayllón ◽  
...  
Keyword(s):  
Cell Death ◽  
Transcription Factors ◽  
Cell Survival ◽  
Binding Sites ◽  
Apoptotic Cell ◽  
Binding Activity ◽  
Interleukin 4 ◽  
Survival Factor ◽  
Induced Apoptosis

ABSTRACT We have analyzed the interleukin-4 (IL-4)-triggered mechanisms implicated in cell survival and show here that IL-4 deprivation induces apoptotic cell death but does not modulate Bcl-2 or Bcl-x expression. Since Bcl-x expression is insufficient to ensure cell survival in the absence of IL-4, we speculate that additional molecules replace the antiapoptotic role of Bcl-2 and Bcl-x in an alternative IL-4-triggered pathway. Cell death is associated with Bcl-3 downregulation and Bcl-3 expression blocks IL-4 deprivation-induced apoptosis, suggesting that Bcl-3 acts as a survival factor in the absence of growth factor. To characterize the IL-4-induced regulation of murine Bcl-3 expression, we cloned the promoter of this gene. Sequencing of the promoter showed no TATA box element but did reveal binding sites for AP1, AP1-like, and SP1 transcription factors. Retardation gels showed that IL-4 specifically induces AP1 and AP1-like binding activity and that mutation of these binding sites abolishes the IL-4-induced Bcl-3 promoter activity, suggesting that these transcription factors are important in Bcl-3 promoter transactivation. IL-4 deprivation induces downregulation of Jun expression and upregulation of Fos expression, both of which are proteins involved in the formation of AP1 and AP1-like transcription factors. Overexpression of Jun family proteins transactivates the promoter and restores Bcl-3 expression in the absence of IL-4 stimulation. Taken together, these data describe a new biological role for Bcl-3 and define the regulatory pathway implicated in Bcl-3 expression.

Abstract 148: Mst1 Mediates Cell-protective Mechanisms In The Heart Through Phosphorylation Of FoxO1 And C/EBP-beta

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Yasuhiro Maejima ◽  
Peiyong Zhai ◽  
Mitsuaki Isobe ◽  
Junichi Sadoshima
Keyword(s):  
Cell Survival ◽  
Posttranslational Modifications ◽  
Leucine Zipper ◽  
Ischemia Reperfusion ◽  
Protective Effects ◽  
Area At Risk ◽  
Protective Mechanisms ◽  
Antioxidant Genes ◽  
Induced Apoptosis

Forkhead box O1 (FoxO1) regulates both cell survival and death in the heart. The function of FoxO1 is modulated by posttranslational modifications, including phosphorylation. Mst1 (mammalian sterile 20-like kinase 1), a stress-activated pro-apoptotic kinase, phosphorylates FoxO1 at Ser209/216/231/232. We investigated the molecular mechanism by which FoxO1 regulates both cell survival and death in the heart. Overexpression of FoxO1 significantly suppressed, whereas downregulation of endogenous FoxO1 exacerbated, Mst1 activity and Mst1-induced apoptosis. In the presence of Mst1, FoxO1 downregulated pro-apoptotic genes, including FasL, but upregulated antioxidant genes, including catalase. Chromatin immunoprecipitation assays revealed that Mst1 attenuated FoxO1 binding to the FasL promoter, but it enhanced binding to the catalase promoter. Reporter gene assays showed that C/EBP-β binding elements, but not the FoxO binding ones, in the catalase promoter, are critical for Mst1-mediated upregulation of the catalase gene. FoxO1 interacted with C/EBP-β and their interaction was enhanced in the presence of Mst1. Mass spectrometry analyses revealed that Mst1 phosphorylates C/EBP-β at Thr 299 in its leucine zipper domain. Downregulation of endogenous C/EBP-β reversed the cell-protective effects of FoxO1 expression against Mst1-induced apoptosis. We evaluated the role of Mst1-mediated phosphorylation of FoxO1 and C/EBP-β in mediating survival and death of cardiomyocytes in response to ischemia/reperfusion (I/R). The size of myocardial infarction (MI) in left ventricle (LV) after I/R was significantly greater in cardiac-specific FoxO1 knockout ( c-FoxO1 -/- ) mice than in wild-type mice (MI/area at risk: 59±2, 41±1%, p <0.05, n=6). Injection of a C/EBP-β phospho-mimetic mutant adenovirus into the LV of c-FoxO1 -/- significantly reduced the I/R-induced LV infarct size observed in c-FoxO1 -/- (50±2%, p <0.05, n=6). In summary, Mst1-mediated phosphorylation of FoxO1 inhibits the DNA binding of FoxO1 to the cell death promoting genes whereas it enhances FoxO1-C/EBP-β interaction, Mst1-mediated phosphorylation of C/EBP-β, and C/EBP-β-mediated transcription, which activates cell-protective mechanisms in the heart.

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