Toxoplasma gondiistabilises tetrameric complexes of tyrosine-phosphorylated signal transducer and activator of transcription-1 and leads to its sustained and promiscuous DNA binding

2018 ◽  
Vol 20 (11) ◽  
pp. e12887 ◽  
Author(s):  
Roswitha Nast ◽  
Julia Staab ◽  
Thomas Meyer ◽  
Carsten G.K. Lüder
Keyword(s):  
Dna Binding ◽  
Signal Transducer ◽  
Promiscuous Dna

scholarly journals Intranuclear Crosstalk between Extracellular Regulated Kinase1/2 and Signal Transducer and Activator of Transcription 3 Regulates JEG-3 Choriocarcinoma Cell Invasion and Proliferation

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Diana M. Morales-Prieto ◽  
Stephanie Ospina-Prieto ◽  
Wittaya Chaiwangyen ◽  
Maja Weber ◽  
Sebastian Hölters ◽  
...  
Keyword(s):  
Dna Binding ◽  
Binding Capacity ◽  
Mapk Signaling ◽  
Signaling Molecules ◽  
Signal Transducer ◽  
Stat3 Phosphorylation ◽  
Functional Implications ◽  
Choriocarcinoma Cells ◽  
Cell Invasiveness ◽  
Transcription 3

Invasiveness of trophoblast and choriocarcinoma cells is in part mediated via leukemia inhibitory factor- (LIF-) induced activation of signal transducer and activator of transcription 3 (STAT3). The regulation of STAT3 phosphorylation at its ser727 binding site, possible crosstalk with intracellular MAPK signaling, and their functional implications are the object of the present investigation. JEG-3 choriocarcinoma cells were cultured in presence/absence of LIF and the specific ERK1/2 inhibitor (U0126). Phosphorylation of signaling molecules (p-STAT3 (ser727 and tyr705) and p-ERK1/2 (thr 202/tyr 204)) was assessed per Western blot. Immunocytochemistry confirmed results, but also pinpointed the location of phosphorylated signaling molecules. STAT3 DNA-binding capacity was studied with a colorimetric ELISA-based assay. Cell viability and invasion capability were assessed by MTS and Matrigel assays. Our results demonstrate that LIF-induced phosphorylation of STAT3 (tyr705 and ser727) is significantly increased after blocking ERK1/2. STAT3 DNA-binding capacity and cell invasiveness are enhanced after LIF stimulation and ERK1/2 blockage. In contrast, proliferation is enhanced by LIF but reduced after ERK1/2 inhibition. The findings herein show that blocking ERK1/2 increases LIF-induced STAT3 phosphorylation and STAT3 DNA-binding capacity by an intranuclear crosstalk, which leads to enhanced invasiveness and reduced proliferation.

Oncostatin M and leukaemia inhibitory factor trigger signal transducer and activator of transcription 3 and extracellular signal-regulated kinase 1/2 pathways but result in heterogeneous cellular responses in trophoblast cells

2016 ◽  
Vol 28 (5) ◽  
pp. 608 ◽  
Author(s):  
Wittaya Chaiwangyen ◽  
Stephanie Ospina-Prieto ◽  
Diana M. Morales-Prieto ◽  
Francisco Lazaro Pereira de Sousa ◽  
Jana Pastuschek ◽  
...  
Keyword(s):  
Dna Binding ◽  
Cell Lines ◽  
Binding Capacity ◽  
Binding Activity ◽  
Oncostatin M ◽  
Inhibitory Factor ◽  
Therapeutic Interventions ◽  
Leukaemia Inhibitory Factor ◽  
Tetrazolium Salt ◽  
Signal Transducer

Leukaemia inhibitory factor (LIF) and oncostatin M (OSM) are pleiotropic cytokines present at the implantation site that are important for the normal development of human pregnancy. These cytokines share the cell membrane receptor subunit gp130, resulting in similar functions. The aim of this study was to compare the response to LIF and OSM in several trophoblast models with particular regard to intracellular mechanisms and invasion. Four trophoblast cell lines with different characteristics were used: HTR-8/SVneo, JEG-3, ACH-3P and AC1-M59 cells. Cells were incubated with LIF, OSM (both at 10 ng mL–1) and the signal transducer and activator of transcription (STAT) 3 inhibitor S3I-201 (200 µM). Expression and phosphorylation of STAT3 (tyr705) and extracellular regulated kinase (ERK) 1/2 (thr202/204) and the STAT3 DNA-binding capacity were analysed by Western blotting and DNA-binding assays, respectively. Cell viability and invasiveness were assessed by the methylthiazole tetrazolium salt (MTS) and Matrigel assays. Enzymatic activity of matrix metalloproteinase (MMP)-2 and MMP-9 was investigated by zymography. OSM and LIF triggered phosphorylation of STAT3 and ERK1/2, followed by a significant increase in STAT3 DNA-binding activity in all tested cell lines. Stimulation with LIF but not OSM significantly enhanced invasion of ACH-3P and JEG-3 cells, but not HTR-8/SVneo or AC1-M59 cells. Similarly, STAT3 inhibition significantly decreased the invasiveness of only ACH-3P and JEG-3 cells concomitant with decreases in secreted MMP-2 and MMP-9. OSM shares with LIF the capacity to activate ERK1/2 and STAT3 pathways in all cell lines tested, but their resulting effects are dependent on cell type. This suggests that LIF and OSM may partially substitute for each other in case of deficiencies or therapeutic interventions.

scholarly journals Epstein-Barr Virus Regulates STAT1 through Latent Membrane Protein 1

2003 ◽  
Vol 77 (7) ◽  
pp. 4439-4443 ◽  
Author(s):  
Ciarán Richardson ◽  
Ceri Fielding ◽  
Martin Rowe ◽  
Paul Brennan
Keyword(s):  
Dna Binding ◽  
Membrane Protein ◽  
Epstein Barr Virus ◽  
Transcriptional Activity ◽  
Latent Membrane Protein ◽  
Latent Membrane Protein 1 ◽  
Signal Transducer ◽  
Barr Virus ◽  
Immortalized Cells ◽  
Epstein Barr

ABSTRACT This study shows a mechanism for the increase of signal transducer and activator of transcription 1 (STAT1) in Epstein-Barr virus-immortalized cells. Latent membrane protein 1 (LMP-1) expression was sufficient to induce STAT1 expression, DNA binding, and transcriptional activity. LMP-1-expressing cells can induce an increase in STAT1 expression in LMP-negative cells in the same culture, suggesting an indirect regulation of STAT1 expression. The increase in STAT1 expression is mediated by the C-terminal activating region 1 (CTAR-1) and/or CTAR-2 domains of LMP-1 and is inhibited by mutant IκB, demonstrating a role for NFκB in LMP-1-mediated STAT1 expression.

scholarly journals The Positively Charged Termini of L2 Minor Capsid Protein Required for Bovine Papillomavirus Infection Function Separately in Nuclear Import and DNA Binding

2004 ◽  
Vol 78 (24) ◽  
pp. 13447-13454 ◽  
Author(s):  
Alyson Fay ◽  
William H. Yutzy ◽  
Richard B. S. Roden ◽  
Junona Moroianu
Keyword(s):  
Dna Binding ◽  
Capsid Protein ◽  
Nuclear Import ◽  
Bovine Papillomavirus ◽  
Sequence Specificity ◽  
Viral Dna ◽  
Minor Capsid Protein ◽  
Nuclear Localization Signals ◽  
Promiscuous Dna ◽  
Positively Charged

ABSTRACT During the papillomavirus (PV) life cycle, the L2 minor capsid protein enters the nucleus twice: in the initial phase after entry of virions into cells and in the productive phase to mediate encapsidation of the newly replicated viral genome. Therefore, we investigated the interactions of the L2 protein of bovine PV type 1 (BPV1) with the nuclear import machinery and the viral DNA. We found that BPV1 L2 bound to the karyopherin α2 (Kap α2) adapter and formed a complex with Kap α2β1 heterodimers. Previous data have shown that the positively charged termini of BPV1 L2 are required for BPV1 infection after the binding of the virions to the cell surface. We determined that these BPV1 L2 termini function as nuclear localization signals (NLSs). Both the N-terminal NLS (nNLS) and the C-terminal NLS (cNLS) interacted with Kap α2, formed a complex with Kap α2β1 heterodimers, and mediated nuclear import via a Kap α2β1 pathway. Interestingly, the cNLS was also the major DNA binding site of BPV1 L2. Consistent with the promiscuous DNA encapsidation by BPV1 pseudovirions, this DNA binding occurred without nucleotide sequence specificity. Moreover, an L2 mutant encoding a scrambled version of the cNLS, which supports production of virions, rescued the DNA binding but not the Kap α2 interaction. These data support a model in which BPV1 L2 functions as an adapter between the viral DNA via the cNLS and the Kaps via the nNLS and facilitates nuclear import of the DNA during infection.

scholarly journals Astaxanthin Ameliorates Lipopolysaccharide-Induced Neuroinflammation, Oxidative Stress and Memory Dysfunction through Inactivation of the Signal Transducer and Activator of Transcription 3 Pathway

Marine Drugs ◽  
2019 ◽  
Vol 17 (2) ◽  
pp. 123 ◽  
Author(s):  
Ji Han ◽  
Yong Lee ◽  
Jun Im ◽  
Young Ham ◽  
Hee Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dna Binding ◽  
Inflammatory Responses ◽  
Memory Loss ◽  
Signal Transducer ◽  
Mice Model ◽  
Neuroinflammatory Response ◽  
Transcription 3

Astaxanthin (AXT), a xanthophyll carotenoid compound, has potent antioxidant, anti-inflammatory and neuroprotective properties. Neuroinflammation and oxidative stress are significant in the pathogenesis and development of Alzheimer’s disease (AD). Here, we studied whether AXT could alleviate neuroinflammation, oxidative stress and memory loss in lipopolysaccharide (LPS) administered mice model. Additionally, we investigated the anti-oxidant activity and the anti-neuroinflammatory response of AXT in LPS-treated BV-2 microglial cells. The AXT administration ameliorated LPS-induced memory loss. This effect was associated with the reduction of LPS-induced expression of inflammatory proteins, as well as the production of reactive oxygen species (ROS), nitric oxide (NO), cytokines and chemokines both in vivo and in vitro. AXT also reduced LPS-induced β-secretase and Aβ1–42 generation through the down-regulation of amyloidogenic proteins both in vivo and in vitro. Furthermore, AXT suppressed the DNA binding activities of the signal transducer and activator of transcription 3 (STAT3). We found that AXT directly bound to the DNA- binding domain (DBD) and linker domain (LD) domains of STAT3 using docking studies. The oxidative stress and inflammatory responses were not downregulated in BV-2 cells transfected with DBD-null STAT3 and LD-null STAT3. These results indicated AXT inhibits LPS-induced oxidant activity, neuroinflammatory response and amyloidogenesis via the blocking of STAT3 activity through direct binding.

scholarly journals S-Glutathionylation Impairs Signal Transducer and Activator of Transcription 3 Activation and Signaling

Endocrinology ◽  
2008 ◽  
Vol 150 (3) ◽  
pp. 1122-1131 ◽  
Author(s):  
Yi Xie ◽  
Sutapa Kole ◽  
Patricia Precht ◽  
Michael J. Pazin ◽  
Michel Bernier
Keyword(s):  
Dna Binding ◽  
Oxidative Modification ◽  
Nuclear Accumulation ◽  
Regulatory Function ◽  
Cysteine Residues ◽  
Pyrrolidine Dithiocarbamate ◽  
Signal Transducer ◽  
Free System ◽  
Stat3 Signaling ◽  
Thiol Reactivity

S-glutathionylation is a physiological, reversible protein modification of cysteine residues with glutathione in response to mild oxidative stress. Because the key cell growth regulator signal transducer and activator of transcription (STAT) 3 is particularly susceptible to redox regulation, we hypothesized that oxidative modification of cysteine residues of STAT3 by S-glutathionylation may occur. Herein, we show that the cysteine residues of STAT3 are modified by a thiol-alkylating agent and are the targets of S-glutathionylation. STAT3 protein thiol reactivity was reversibly attenuated with concomitant increase in the S-glutathionylation of STAT3 upon treatment of human HepG2 hepatoma cells with pyrrolidine dithiocarbamate, glutathione disulfide, or diamide. Under these conditions there was a marked reduction in IL-6-dependent STAT3 signaling, including decreased STAT3 tyrosine phosphorylation, loss in nuclear accumulation of STAT3, and impaired expression of target genes, such as fibrinogen-γ. In a cell-free system, diamide induced glutathionylation of STAT3, which was decreased upon addition of glutaredoxin (GRX)-1, a deglutathionylation enzyme, or the reducing agent, dithiothreitol. Glutathionylated STAT3 was a poor Janus protein tyrosine kinase 2 substrate in vitro, and it exhibited low DNA-binding activity. Cellular GRX-1 activity was inhibited by diamide and pyrrolidine dithiocarbamate treatment; however, ectopic expression of GRX-1 was accompanied by a modest increase in phosphorylation, nuclear translocation, and DNA-binding ability of STAT3 in response to IL-6. These results are the first to show S-glutathionylation of STAT3, a modification that may exert regulatory function in STAT3 signaling. Reversible S-glutathionylation of STAT3 regulates its activity as transcription factor.

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