The balance of serine and tyrosine phosphorylation of signal transducer and activator of transcription 3 (STAT3) in Jeg-3 choriocarcinoma cells

2007 ◽  
Vol 75 (1) ◽  
pp. A14
Author(s):  
J. Roediger ◽  
S. Busch ◽  
A. Enkelmann ◽  
T.G. Poehlmann ◽  
E. Schleussner ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Signal Transducer ◽  
Choriocarcinoma Cells ◽  
Transcription 3

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.

scholarly journals Midkine Is an Autocrine Activator of Signal Transducer and Activator of Transcription 3 in 3T3-L1 Cells

Endocrinology ◽  
2007 ◽  
Vol 148 (4) ◽  
pp. 1598-1604 ◽  
Author(s):  
Erin R. Cernkovich ◽  
Jianbei Deng ◽  
Kunjie Hua ◽  
Joyce B. Harp
Keyword(s):  
Tyrosine Phosphorylation ◽  
Neutralizing Antibodies ◽  
Clonal Expansion ◽  
Dependent Manner ◽  
Signal Transducer ◽  
Heparin Binding ◽  
Paracrine Factor ◽  
Signaling Protein ◽  
Mitotic Clonal Expansion ◽  
Transcription 3

Mitotic clonal expansion is believed to be necessary for 3T3-L1 adipocyte formation. Signal transducer and activator of transcription 3 (STAT3), a mitogenic signaling protein, is activated through tyrosine phosphorylation during the proliferative phases of adipogenesis. We hypothesize that this signaling protein plays a key role in mitotic clonal expansion and differentiation. Here we determined that the adipocyte differentiation cocktail containing isobutylmethylxanthine, dexamethasone, and insulin (MDI) induced STAT3 tyrosine phosphorylation indirectly through the synthesis of an autocrine/paracrine factor. We further determined that the factor has heparin binding properties and identified the factor as midkine, a pleiotrophic growth factor previously associated with neuronal development and oncogenesis. Recombinant midkine induced STAT3 tyrosine phosphorylation in a time- and dose-dependent manner and stimulated the proliferation of postconfluent 3T3-L1 cells. Midkine neutralizing antibodies inhibited differentiation-induced STAT3 tyrosine phosphorylation as well as adipogenesis. These results show that MDI-induced synthesis and release of midkine explains the delayed activation of STAT3 during adipogenesis and that the midkine-STAT3 signaling pathway plays a necessary role in mitotic clonal expansion and differentiation.

scholarly journals Chronic Tumor Necrosis Factor-α Treatment Causes Insulin Resistance via Insulin Receptor Substrate-1 Serine Phosphorylation and Suppressor of Cytokine Signaling-3 Induction in 3T3-L1 Adipocytes

Endocrinology ◽  
2007 ◽  
Vol 148 (6) ◽  
pp. 2994-3003 ◽  
Author(s):  
Ken Ishizuka ◽  
Isao Usui ◽  
Yukiko Kanatani ◽  
Agussalim Bukhari ◽  
Jianying He ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Tyrosine Phosphorylation ◽  
Insulin Signaling ◽  
Serine Phosphorylation ◽  
Cytokine Signaling ◽  
Insulin Receptor Substrate ◽  
Signal Transducer ◽  
Suppressor Of Cytokine Signaling ◽  
Transcription 3

Serine phosphorylation of insulin receptor substrate (IRS)-1 and the induction of suppressor of cytokine signaling 3 (SOCS3) is recently well documented as the mechanisms for the insulin resistance. However, the relationship between these two mechanisms is not fully understood. In this study, we investigated the involvement of SOCS3 and IRS-1 serine phosphorylation in TNFα-induced insulin resistance in 3T3-L1 adipocytes. TNFα transiently stimulated serine phosphorylation of IRS-1 from 10 min to 1 h, whereas insulin-stimulated IRS-1 tyrosine phosphorylation was inhibited only after TNFα treatment longer than 4 h. These results suggest that serine phosphorylation of IRS-1 alone is not the major mechanism for the inhibited insulin signaling by TNFα. TNFα stimulation longer than 4 h enhanced the expression of SOCS3 and signal transducer and activator of transcription-3 phosphorylation, concomitantly with the production of IL-6. Anti-IL-6 neutralizing antibody ameliorated suppressed insulin signaling by 24 h TNFα treatment, when it partially decreased SOCS3 induction and signal transducer and activator of transcription-3 phosphorylation. These results suggest that SOCS3 induction is involved in inhibited insulin signaling by TNFα. However, low-level expression of SOCS3 by IL-6 or adenovirus vector did not affect insulin-stimulated IRS-1 tyrosine phosphorylation. Interestingly, when IRS-1 serine phosphorylation was enhanced by TNFα or anisomycin in the presence of low-level SOCS3, IRS-1 degradation was remarkably enhanced. Taken together, both IRS-1 serine phosphorylation and SOCS3 induction are necessary, but one of the pair is not sufficient for the inhibited insulin signaling. Chronic TNFα may inhibit insulin signaling effectively because it causes both IRS-1 serine phosphorylation and the following SOCS3 induction in 3T3-L1 adipocytes.

scholarly journals Analysis of Stat3 (signal transducer and activator of transcription 3) dimerization by fluorescence resonance energy transfer in living cells

2004 ◽  
Vol 377 (2) ◽  
pp. 289-297 ◽  
Author(s):  
Antje K. KRETZSCHMAR ◽  
Michaela C. DINGER ◽  
Christian HENZE ◽  
Katja BROCKE-HEIDRICH ◽  
Friedemann HORN
Keyword(s):  
Energy Transfer ◽  
Tyrosine Phosphorylation ◽  
Fluorescence Resonance Energy Transfer ◽  
Fusion Proteins ◽  
Fluorescent Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Sh2 Domain ◽  
Signal Transducer ◽  
Transcription 3

Signal transducer and activator of transcription 3 (Stat3) dimerization is commonly thought to be triggered by its tyrosine phosphorylation in response to interleukin-6 (IL-6) or other cytokines. Accumulating evidence from in vitro studies, however, suggests that cytoplasmic Stat3 may be associated with high-molecular-mass protein complexes and/or dimerize prior to its activation. To directly study Stat3 dimerization and subcellular localization upon cytokine stimulation, we used live-cell fluorescence spectroscopy and imaging microscopy combined with fluorescence resonance energy transfer (FRET). Stat3 fusion proteins with spectral variants of green fluorescent protein (GFP), cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) were constructed and expressed in human hepatoma cells (HepG2) and human embryonic kidney cells (HEK-293). Like wild-type Stat3, the fusion proteins redistributed from a preferentially cytoplasmic to nuclear localization upon IL-6 stimulation and supported IL-6-dependent target gene expression. FRET studies in cells co-expressing Stat3–CFP and Stat3–YFP demonstrated that Stat3 dimers exist in the absence of tyrosine phosphorylation. IL-6 induced a 2-fold increase of this basal FRET signal, indicating that tyrosine phosphorylation either increases the dimer/monomer ratio of Stat3 or induces a conformational change of the dimer yielding a higher FRET efficiency. Studies using a mutated Stat3 with a non-functional src-homology 2 (SH2) domain showed that the SH2 domain is essential for dimer formation of phosphorylated as well as non-phosphorylated Stat3. Furthermore, our data show that visualization of normalized FRET signals allow insights into the spatiotemporal dynamics of Stat3 signal transduction.

Hypoxia is a potent inducer of the iron masterswitch hepcidin via Signal Transducer and Activator of Transcription 3 (STAT3)

2017 ◽  
Author(s):  
I Silva ◽  
V Rausch ◽  
T Peccerella ◽  
G Millonig ◽  
HK Seitz ◽  
...  
Keyword(s):  
Signal Transducer ◽  
Potent Inducer ◽  
Transcription 3
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