scholarly journals Thrombopoietin induces tyrosine phosphorylation and activation of the Janus kinase, JAK2

Blood ◽  
1995 ◽  
Vol 85 (12) ◽  
pp. 3444-3451 ◽  
Author(s):  
PJ Tortolani ◽  
JA Johnston ◽  
CM Bacon ◽  
DW McVicar ◽  
A Shimosaka ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Cell Line ◽  
Tyrosine Phosphorylation ◽  
Molecular Mechanisms ◽  
Janus Kinase ◽  
Janus Kinases ◽  
Differentiation Factor ◽  
Megakaryocytic Cell

Thrombopoietin (TPO) is a recently characterized growth and differentiation factor for megakaryocytes and platelets that exerts its effects via the receptor, c-MpI. This receptor is a member of the hematopoietin receptor superfamily and is essential for megakaryocyte maturation; however, the molecular mechanisms of TPO and c-MpI action have not been elucidated. Recently, the Janus kinases have emerged as important elements in signaling via this family of receptors. In this report, we show that, in the M07e megakaryocytic cell line, which expresses c-MpI and proliferates in response to TPO, TPO induces phosphorylation of a number of substrates between 80 and 140 kD. Specifically, we show that stimulation with TPO induces the rapid tyrosine phosphorylation of a 130-kD protein that we identify as the Janus kinase, JAK2. However, no detectable tyrosine phosphorylation of JAK1, JAK3, or TYK2 was observed. TPO also induced activation of JAK2 phosphotransferase activity in vitro. Taken together, these data indicate that JAK2 likely plays a key role in TPO-mediated signal transduction.

scholarly journals Stat1 associates with c-kit and is activated in response to stem cell factor

1997 ◽  
Vol 327 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Candy DeBERRY ◽  
Sherry MOU ◽  
Diana LINNEKIN
Keyword(s):  
Signal Transduction ◽  
Stem Cell ◽  
Cell Line ◽  
Progenitor Cells ◽  
Fusion Proteins ◽  
Stem Cell Factor ◽  
Sh2 Domain ◽  
Janus Kinase ◽  
Mobility Shift

Interaction of stem cell factor (SCF), a haematopoietic growth factor, with the receptor tyrosine kinase c-kit leads to autophosphorylation of c-kit as well as tyrosine phosphorylation of various substrates. Little is known about the role of the JAK/STAT pathway in signal transduction via receptor tyrosine kinases, although this pathway has been well characterized in cytokine receptor signal transduction. We recently found that the Janus kinase Jak2 associates with c-kit and that SCF induces rapid and transient phosphorylation of Jak2. Here we present evidence that SCF activates the transcription factor Stat1. Phosphorylated c-kit co-immunoprecipitates with Stat1 within 1 min of SCF stimulation of the human cell line MO7e. Co-precipitation experiments using glutathione S-transferase fusion proteins indicate that association with c-kit is mediated by the Stat1 SH2 domain. Stat1 is rapidly tyrosine-phosphorylated in response to SCF in MO7e cells, the murine cell line FDCP-1 and normal progenitor cells. SCF-induced phosphorylation of Jak2 and Stat1 was also observed in murine 3T3 fibroblasts stably transfected with full-length human c-kit receptor. Furthermore c-kit directly phosphorylates Stat1 fusion proteins in in vitro kinase assays. Electrophoretic mobility-shift assays with nuclear extracts from SCF-stimulated cell lines and normal progenitor cells indicate that activated Stat1 binds the m67 oligonucleotide, a high-affinity SIE promoter sequence. These results demonstrate that Stat1 is activated in response to SCF, and suggest that Stat1 is a component of the SCF signal-transduction pathway.

scholarly journals Anti-Fibrosis Effects of Magnesium Lithospermate B in Experimental Pulmonary Fibrosis: By Inhibiting TGF-βRI/Smad Signaling

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1715
Author(s):  
Xin Luo ◽  
Qiangqiang Deng ◽  
Yaru Xue ◽  
Tianwei Zhang ◽  
Zhitao Wu ◽  
...  
Keyword(s):  
Pulmonary Fibrosis ◽  
Cell Line ◽  
Molecular Mechanisms ◽  
Transforming Growth Factor ◽  
Salvia Miltiorrhiza ◽  
A549 Cells ◽  
Epithelial Cell Line ◽  
Human Lung Fibroblast ◽  
Magnesium Lithospermate B

Pulmonary fibrosis is a severe and irreversible interstitial pulmonary disease with high mortality and few treatments. Magnesium lithospermate B (MLB) is a hydrosoluble component of Salvia miltiorrhiza and has been reported to have antifibrotic effects in other forms of tissue fibrosis. In this research, we studied the effects of MLB on pulmonary fibrosis and the underlying mechanisms. Our results indicated that MLB treatment (50 mg/kg) for seven days could attenuate bleomycin (BLM)-induced pulmonary fibrosis by reducing the alveolar structure disruption and collagen deposition in the C57 mouse model. MLB was also found to inhibit transforming growth factor-beta (TGF-β)-stimulated myofibroblastic transdifferentiation of human lung fibroblast cell line (MRC-5) cells and collagen production by human type II alveolar epithelial cell line (A549) cells, mainly by decreasing the expression of TGF-β receptor I (TGF-βRI) and regulating the TGF-β/Smad pathway. Further studies confirmed that the molecular mechanisms of MLB in BLM-induced pulmonary fibrosis mice were similar to those observed in vitro. In summary, our results demonstrated that MLB could alleviate experimental pulmonary fibrosis both in vivo and in vitro, suggesting that MLB has great potential for pulmonary fibrosis treatment.

scholarly journals Analysis of a Preliminary microRNA Expression Signature in a Human Telangiectatic Osteogenic Sarcoma Cancer Cell Line

2021 ◽  
Vol 22 (3) ◽  
pp. 1163
Author(s):  
Gaia Palmini ◽  
Cecilia Romagnoli ◽  
Simone Donati ◽  
Roberto Zonefrati ◽  
Gianna Galli ◽  
...  
Keyword(s):  
Cell Line ◽  
Molecular Mechanisms ◽  
Osteogenic Sarcoma ◽  
Cancer Cell Line ◽  
Microscopic Features ◽  
In Vitro Establishment ◽  
Profile Characteristic ◽  
First Time

Telangiectatic osteosarcoma (TOS) is an aggressive variant of osteosarcoma (OS) with distinctive radiographic, gross, microscopic features, and prognostic implications. Despite several studies on OS, we are still far from understanding the molecular mechanisms of TOS. In recent years, many studies have demonstrated not only that microRNAs (miRNAs) are involved in OS tumorigenesis, development, and metastasis, but also that the presence in high-grade types of OS of cancer stem cells (CSCs) plays an important role in tumor progression. Despite these findings, nothing has been described previously about the expression of miRNAs and the presence of CSCs in human TOS. Therefore, we have isolated/characterized a putative CSC cell line from human TOS (TOS-CSCs) and evaluated the expression levels of several miRNAs in TOS-CSCs using real-time quantitative assays. We show, for the first time, the existence of CSCs in human TOS, highlighting the in vitro establishment of this unique stabilized cell line and an identification of a preliminary expression of the miRNA profile, characteristic of TOS-CSCs. These findings represent an important step in the study of the biology of one of the most aggressive variants of OS and the role of miRNAs in TOS-CSC behavior.

scholarly journals In vitro expression of long and short ovine prolactin receptors: activation of Jak2/STAT5 pathway is not sufficient to account for prolactin signal transduction to the ovine beta-lactoglobulin gene promoter

1999 ◽  
Vol 23 (2) ◽  
pp. 125-136 ◽  
Author(s):  
C Bignon ◽  
N Daniel ◽  
L Belair ◽  
J Djiane
Keyword(s):  
Tyrosine Phosphorylation ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Gene Promoter ◽  
Janus Kinase ◽  
Prolactin Receptors ◽  
Milk Protein Gene ◽  
Prolactin Signaling ◽  
Beta Lactoglobulin

The recent finding that sheep had long (l-oPRLR) and short (s-oPRLR) prolactin receptors provided new tools to further explore prolactin signaling to target genes. Here we used CHO cells transfected with l-oPRLR or s-oPRLR cDNAs to compare the activation of known key steps of prolactin signaling by the two receptors. We found that prolactin stimulated l-oPRLR tyrosine phosphorylation, although it lacked the last tyrosine residue found in other long prolactin receptors. In addition, l-oPRLR and s-oPRLR both responded to prolactin stimulation by (1) Janus kinase 2 (Jak2) tyrosine phosphorylation, (2) DNA-binding activation of signal transducer and activator of transcription 5 (STAT5), (3) stimulation of transcription from a promoter made of six repeats of STAT5-responsive sequence. However, although it contains STAT5-binding consensus sequences, the ovine beta-lactoglobulin promoter (-4000 to +40) was transactivated by l-oPRLR, but not by s-oPRLR. Taken together, our results indicate that activation of Jak2/STAT5 pathway alone is not sufficient to account for prolactin-induced transcription of this milk protein gene, and that sequences of its promoter, other than STAT5-specific sequences, account for the opposite transcriptional activation capabilities of l-oPRLR and s-oPRLR.

scholarly journals CNPY4 inhibits the Hedgehog pathway by modulating membrane sterol lipids

2021 ◽  
Author(s):  
Megan Lo ◽  
Amnon Sharir ◽  
Michael D Paul ◽  
Hayarpi Torosyan ◽  
Christopher Agnew ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Primary Cilia ◽  
Molecular Mechanisms ◽  
Negative Regulator ◽  
Membrane Composition ◽  
Hh Signaling ◽  
Pathway Regulation ◽  
Patched 1 ◽  
Cancer Signal Transduction

The Hedgehog (HH) pathway is critical for development and adult tissue homeostasis. Aberrant HH signaling can cause congenital malformations, such as digit anomalies and holoprosencephaly, and other diseases, including cancer. Signal transduction is initiated by HH ligand binding to the Patched 1 (PTCH1) receptor on primary cilia, thereby releasing inhibition of Smoothened (SMO), a HH pathway activator. Although cholesterol and several oxysterol lipids, which are enriched in the ciliary membrane, play a crucial role in HH activation, the molecular mechanisms governing the regulation of these lipid molecules remain unresolved. Here, we identify Canopy 4 (CNPY4), a Saposin-like protein, as a regulator of the HH pathway that controls membrane sterol lipid levels. Cnpy4—/— embryos exhibit multiple defects consistent with HH signaling perturbations, most notably changes in digit number. Knockdown of Cnpy4 hyperactivates the HH pathway at the level of SMO in vitro, and elevates membrane levels of accessible sterol lipids such as cholesterol, an endogenous ligand involved in SMO activation. Thus, our data demonstrate that CNPY4 is a negative regulator that fine-tunes the initial steps of HH signal transduction, revealing a previously undescribed facet of HH pathway regulation that operates through control of membrane composition.

scholarly journals Lymphoma regression induced by monoclonal anti-idiotypic antibodies correlates with their ability to induce Ig signal transduction and is not prevented by tumor expression of high levels of bcl-2 protein

Blood ◽  
1994 ◽  
Vol 83 (4) ◽  
pp. 899-906 ◽  
Author(s):  
WM Vuist ◽  
R Levy ◽  
DG Maloney
Keyword(s):  
Signal Transduction ◽  
Tumor Cells ◽  
Tyrosine Phosphorylation ◽  
Tumor Regression ◽  
Cellular Protein ◽  
Protein Tyrosine Phosphorylation ◽  
Custom Made ◽  
Tumor Expression ◽  
Complete Tumor

Abstract Custom-made monoclonal anti-idiotype antibodies (anti-Id MoAbs) have been tested as a treatment modality in 34 non-Hodgkin's lymphoma (NHL) patients. Partial or complete tumor remissions have been induced with this treatment in 68% of these patients. One mechanism by which anti- idiotype antibodies may have induced these tumor responses is via a direct antiproliferative effect on the tumor cells, resulting in apoptosis. Primary NHL cells do not proliferate well enough in vitro to test this hypothesis directly. Therefore, we studied the effect of anti-idiotype antibodies on signal transduction through the surface Ig receptor as measured by the induction of cellular protein tyrosine phosphorylation. To assess whether bcl-2 protein could protect lymphoma cells from death induced by anti-Id MoAb, we also measured the level of bcl-2 protein in the same tumor cells. We found a strong correlation between the ability of an anti-Id MoAb to induce an increase in tyrosine phosphorylation in vitro and its ability to induce a tumor regression in the patient. By contrast, the level of bcl-2 expressed by the tumor cells was not correlated with clinical response to anti-Id MoAb treatment.

scholarly journals Silencing of lncRNA MIR497HG via CRISPR/Cas13d Induces Bladder Cancer Progression Through Promoting the Crosstalk Between Hippo/Yap and TGF-β/Smad Signaling

2020 ◽  
Vol 7 ◽  
Author(s):  
Changshui Zhuang ◽  
Ying Liu ◽  
Shengqiang Fu ◽  
Chaobo Yuan ◽  
Jingwen Luo ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Cell Line ◽  
Cancer Progression ◽  
Molecular Mechanisms ◽  
Transforming Growth Factor ◽  
Transforming Growth Factor Β ◽  
Pathological Process ◽  
The Cancer Genome Atlas ◽  
Migration And Invasion

A subset of long non-coding RNAs (lncRNAs), categorized as miRNA-host gene lncRNAs (lnc-miRHGs), is processed to produce miRNAs and involved in cancer progression. This work aimed to investigate the influences and the molecular mechanisms of lnc-miRHGs MIR497HG in bladder cancer (BCa). The miR-497 and miR-195 were derived from MIR497HG. We identified that lnc-miRHG MIR497HG and two harbored miRNAs, miR-497 and miR-195, were downregulated in BCa by analyzing The Cancer Genome Atlas and our dataset. Silencing of MIR497HG by CRISPR/Cas13d in BCa cell line 5637 promoted cell growth, migration, and invasion in vitro. Conversely, overexpression of MIR497HG suppressed cell progression in BCa cell line T24. MiR-497/miR-195 mimics rescued significantly the oncogenic roles of knockdown of MIR497HG by CRISPR/Cas13d in BCa. Mechanistically, miR-497 and miR-195 co-ordinately suppressed multiple key components in Hippo/Yap and transforming growth factor β signaling and particularly attenuated the interaction between Yap and Smad3. In addition, E2F4 was proven to be critical for silencing MIR497HG transcription in BCa cells. In short, we propose for the first time to reveal the function and mechanisms of MIR497HG in BCa. Blocking the pathological process may be a potential strategy for the treatment of BCa.

scholarly journals Overexpression of cyclin D1 in the Dami megakaryocytic cell line causes growth arrest

Blood ◽  
1995 ◽  
Vol 86 (1) ◽  
pp. 294-304 ◽  
Author(s):  
CC Wilhide ◽  
C Van Dang ◽  
J Dipersio ◽  
AA Kenedy ◽  
PF Bray
Keyword(s):  
Cyclin D1 ◽  
Cell Line ◽  
Cell Lines ◽  
Northern Blotting ◽  
Mrna Levels ◽  
Cyclin Dependent Kinases ◽  
Megakaryocyte Differentiation ◽  
Megakaryocytic Cell

The maturation of megakaryocytes in vivo requires polyploidization or repeated duplication of DNA without cytokinesis. As DNA replication and cytokinesis are tightly regulated in somatic cells by cyclins and cyclin-dependent kinases, we sought to determine the pattern of cyclin gene expression in cells that undergo megakaryocytic differentiation and polyploidization. The Dami megakaryocytic cell line differentiates and increases ploidy in response to phorbol 12-myristate 13-acetate (PMA) stimulation in vitro. We used Northern blotting to analyze mRNA levels of cyclins A, B, C, D1, and E in PMA-induced Dami cells and found that cyclin D1 mRNA levels increased dramatically (18-fold). Similar increases in cyclin D1 mRNA were obtained for other cell lines (HEL and K562) with megakaryocytic properties, but not in HeLa cells. The increase in cyclin D1 was confirmed by Western immunoblotting of PMA-treated Dami cells. This finding suggested that cyclin D1 might participate in megakaryocyte differentiation by promoting endomitosis and/or inhibiting cell division. To address these possibilities, we constructed two stable Zn+2-inducible, cyclin D1-overexpressing Dami cell lines. Cyclin D1 expression alone was not sufficient to induce polyploidy, but in conjunction with PMA-induced differentiation, polyploidization was slightly enhanced. However, unlike other cell systems, cyclin D1 overexpression caused cessation of cell growth. Although the mechanism by which cyclin D1 may affect megakaryocyte differentiation is not clear, these data demonstrate that cyclin D1 is upregulated in differentiating megakaryocytic cells and may contribute to differentiation by arresting cell proliferation.

scholarly journals Interleukin-2 induces tyrosine phosphorylation of the vav proto-oncogene product in human T cells: lack of requirement for the tyrosine kinase lck

1993 ◽  
Vol 294 (2) ◽  
pp. 339-342 ◽  
Author(s):  
G A Evans ◽  
O M Z Howard ◽  
R Erwin ◽  
W L Farrar
Keyword(s):  
Signal Transduction ◽  
T Cells ◽  
Tyrosine Kinase ◽  
Cell Line ◽  
Tyrosine Phosphorylation ◽  
Interleukin 2 ◽  
Maximum Increase ◽  
Human T Cell ◽  
Human T Cells ◽  
Stimulation Of

The haematopoietic protein, p95vav, has been shown to be a tyrosine kinase substrate and to have tyrosine kinase-modulated guanine-nucleotide-releasing-factor activity. This implies a function in the control of ras or ras-like proteins. Because ras activation has been shown to be a downstream event following stimulation of the interleukin-2 (IL-2) receptor, we investigated the possibility that vav was involved in IL-2 signal transduction pathways, using human T cells as a model. We found rapid tyrosine phosphorylation of vav in response to IL-2 within 1 min, with maximum increase of phosphorylation of 5-fold occurring by 5 min after treatment in normal human T cells. IL-2 stimulation of the human T-cell line YT and a subclone of the YT cell line (YTlck-) that does not express message for the src-family kinase p56lck also results in a rapid rate of tyrosine phosphorylation of vav of more than 5-fold by 5 min. These results suggest that vav may play an important role in IL-2-stimulated signal transduction and that there is not a strict requirement for the tyrosine kinase p56lck.

scholarly journals Effects of Chronic Ethanol on Hepatic and Renal CYP2C11 in the Male Rat: Interactions with the Janus-Kinase 2-Signal Transducer and Activators of Transcription Proteins 5b Pathway

Endocrinology ◽  
2003 ◽  
Vol 144 (9) ◽  
pp. 3969-3976 ◽  
Author(s):  
T. M. Badger ◽  
M. J. J. Ronis ◽  
S. J. Frank ◽  
Y. Chen ◽  
L. He
Keyword(s):  
Signal Transduction ◽  
Signal Transduction Pathway ◽  
Serum Testosterone ◽  
Janus Kinase ◽  
Chronic Ethanol ◽  
Male Rats ◽  
Male Rat ◽  
Signal Transducer ◽  
Transduction Pathway

Abstract Chronic alcohol intake in male rats results in: 1) demasculinization of the GH pulse pattern; 2) reduced serum testosterone concentrations; and 3) decreased expression hepatic CYP2C11. Hepatic CYP2C11 expression is regulated by the male pattern of GH through the Janus-kinase/signal transducer and activators of transcription proteins (JAK/STAT) signal transduction pathway in the male rat. Renal CYP2C11 is regulated by testosterone, not GH. The involvement of the JAK/STAT5b signal transduction pathway in renal CYP2C11 signaling has not been studied. We tested the hypothesis that ethanol reduces CYP2C11 levels by interfering with the JAK/STAT5b pathway. Using a total enteral nutrition (TEN) model to feed rats a well-balanced diet, we have studied the effects of chronic ethanol intake (21 d) on hepatic and renal JAK/STAT pathway of adult male rats (8–10/group). We found decreased hepatic and renal expression of CYP2C11 in ethanol-fed rats with concomitant decreases in STAT5b and phospho-STAT5b, decreased in vitro hepatic STAT5b binding to a CYP2C11 promoter element and no effects on hepatic GHR levels. Ethanol caused tissue specific effects in phospho-JAK2 and JAK2, with increased levels in the liver, but decreased JAK2 expression in the kidney. We conclude that ethanol suppression of CYP2C11 expression is clearly associated with reductions in STAT5b levels, but not necessarily in reductions of JAK2 levels. The mechanisms underlying ethanol-induced suppression of STAT5b is yet to be determined, as is the question of whether this is secondary to hormonal effects or a direct ethanol effect.

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