Lyn tyrosine kinase regulates thrombopoietin-induced proliferation of hematopoietic cell lines and primary megakaryocytic progenitors

Blood ◽  
2004 ◽  
Vol 103 (10) ◽  
pp. 3736-3743 ◽  
Author(s):  
Brian J. Lannutti ◽  
Jonathan G. Drachman
Keyword(s):  
Cellular Proliferation ◽  
Kinase Inhibitors ◽  
Dominant Negative ◽  
Janus Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Mapk Activity ◽  
Targeted Mutation ◽  
Mitogen Activated Protein ◽  
Nuclear Ploidy

Abstract In this study we demonstrate that thrombopoietin (TPO)–stimulated Src family kinases (SFKs) inhibit cellular proliferation and megakaryocyte differentiation. Using the Src kinase inhibitors pyrolopyrimidine 1 and 2 (PP1, PP2), we show that TPO-dependent proliferation of BaF3/Mpl cells was enhanced at concentrations that are specific for SFKs. Similarly, proliferation is increased after introducing a dominant-negative form of Lyn into BaF3/Mpl cells. Murine marrow cells from Lyn-deficient mice or wild-type mice cultured in the presence of the Src inhibitor, PP1, yielded a greater number of mature megakaryocytes and increased nuclear ploidy. Truncation and targeted mutation of the Mpl cytoplasmic domain indicate that Y112 is critical for Lyn activation. Examining the molecular mechanism for this antiproliferative effect, we determined that SFK inhibitors did not affect tyrosine phosphorylation of Janus kinase 2 (JAK2), Shc, signal transducer and activator of transcription (STAT)5, or STAT3. In contrast, pretreatment of cells with PP2 increased Erk1/2 (mitogen-activated protein kinase [MAPK]) phosphorylation and in vitro kinase activity, particularly after prolonged TPO stimulation. Taken together, our results show that Mpl stimulation results in the activation of Lyn kinase, which appears to limit the proliferative response through a signaling cascade that regulates MAPK activity. These data suggest that SFKs modify the rate of TPO-induced proliferation and are likely to affect cell cycle regulation during megakaryocytopoiesis.

scholarly journals Regulation of PDGFR-α in rat pulmonary myofibroblasts by staurosporine

2001 ◽  
Vol 280 (2) ◽  
pp. L354-L362 ◽  
Author(s):  
Pamela M. Lindroos ◽  
Yi-Zhe Wang ◽  
Annette B. Rice ◽  
James C. Bonner
Keyword(s):  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Protein A ◽  
Nuclear Factor Κb ◽  
Mitogen Activated Protein Kinase ◽  
Specific Gene ◽  
Autocrine Loop ◽  
P38 Inhibitor ◽  
Mitogen Activated Protein

Upregulation of the platelet-derived growth factor (PDGF) receptor-α (PDGFR-α) is a mechanism of myofibroblast hyperplasia during pulmonary fibrosis. We previously identified interleukin (IL)-1β as a major inducer of the PDGFR-α in rat pulmonary myofibroblasts in vitro. In this study, we report that staurosporine, a broad-spectrum kinase inhibitor, upregulates PDGFR-α gene expression and protein. A variety of other kinase inhibitors did not induce PDGFR-α expression. Staurosporine did not act via an IL-1β autocrine loop because the IL-1 receptor antagonist protein did not block staurosporine-induced PDGFR-α expression. Furthermore, staurosporine did not activate a variety of signaling molecules that were activated by IL-1β, including nuclear factor-κB, extracellular signal-regulated kinase, and c-Jun NH2-terminal kinase. However, both staurosporine- and IL-1β-induced phosphorylation of p38 mitogen-activated protein kinase and upregulation of PDGFR-α by these two agents was inhibited by the p38 inhibitor SB-203580. Finally, staurosporine inhibited basal and PDGF-stimulated mitogenesis over the same concentration range that induced PDGFR-α expression. Collectively, these data demonstrate that staurosporine is a useful tool for elucidating the signaling mechanisms that regulate PDGFR expression in lung connective tissue cells and possibly for evaluating the role of the PDGFR-α as a growth arrest-specific gene.

Clinical efficacy with dabrafenib and trametinib in a T599_V600insT poorly differentiated metastatic thyroid carcinoma

2021 ◽  
Vol 14 (8) ◽  
pp. e243264
Author(s):  
Chung-Shien Lee ◽  
Emily Miao ◽  
Kasturi Das ◽  
Nagashree Seetharamu
Keyword(s):  
Thyroid Carcinoma ◽  
Kinase Inhibitors ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Braf Mutations ◽  
Effective Treatment Option ◽  
Mitogen Activated Protein ◽  
Treatment Data ◽  
Poorly Differentiated

BRAF (v-raf murine sarcoma viral oncogene homolog B1) and MEK (mitogen-activated protein kinase kinase) inhibitors have been shown to improve clinical outcomes in tumours presenting with mutations in the BRAF gene. The most common form of BRAF mutation is V600E/K and has been shown to occur in thyroid cancers. Treatment data for patients harbouring less frequent BRAF mutations are limited. In vitro studies have shown that mutations in codons 599–601 increase kinase activity similar to that in V600E mutations, which suggests that BRAF and MEK inhibitors could be an effective treatment option. Here, we report a case of a patient with thyroid carcinoma harbouring a rare amino acid insertion in codon 599 of the BRAF gene (T599_V600insT) treated with a BRAF and MEK inhibitor.

scholarly journals Positive and negative selection invoke distinct signaling pathways.

1996 ◽  
Vol 184 (1) ◽  
pp. 9-18 ◽  
Author(s):  
J Alberola-Ila ◽  
K A Hogquist ◽  
K A Swan ◽  
M J Bevan ◽  
R M Perlmutter
Keyword(s):  
T Cell ◽  
Positive Selection ◽  
Negative Selection ◽  
Mapk Pathway ◽  
Cell Receptor ◽  
Dominant Negative ◽  
Mapk Cascade ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein

During T cell development, interaction of the T cell receptor (TCR) with cognate ligands in the thymus may result in either maturation (positive selection) or death (negative selection). The intracellular pathways that control these opposed outcomes are not well characterized. We have generated mice expressing dominant-negative Ras (dnRas) and Mek-1 (dMek) transgenes simultaneously, either in otherwise normal animals, or in animals expressing a transgenic TCR, thereby permitting a comprehensive analysis of peptide-specific selection. In this system, thymocyte maturation beyond the CD4+8+ stage is blocked almost completely, whereas negative selection, assessed using an in vitro deletion protocol, is quantitatively intact. This suggests that activation of the mitogen-activated protein kinase (MAPK) cascade is necessary for positive selection, but irrelevant for negative selection. Generation of gamma/delta and of CD4-8- alpha/beta T cells proceeds normally despite blockade of the MAPK cascade. Hence, only cells that mature via conventional, TCR-mediated repertoire selection require activation of the MAPK pathway to complete their maturation.

scholarly journals Mitogen-activated protein kinase-mediated phosphorylation of peroxiredoxin 6 regulates its phospholipase A2 activity

2009 ◽  
Vol 419 (3) ◽  
pp. 669-679 ◽  
Author(s):  
Yongzheng Wu ◽  
Sheldon I. Feinstein ◽  
Yefim Manevich ◽  
Ibrul Chowdhury ◽  
Jhang Ho Pak ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Phospholipase A2 ◽  
Kinase Inhibitors ◽  
Phosphorylation Site ◽  
Protein Kinase Inhibitors ◽  
Mitogen Activated Protein Kinase ◽  
Alveolar Type ◽  
Peroxiredoxin 6 ◽  
Mitogen Activated Protein

Prdx6 (peroxiredoxin 6), a bifunctional protein with both GSH peroxidase and PLA2 (phospholipase A2) [aiPLA2 (acidic calcium-independent PLA2)] activities, is responsible for the metabolism of lung surfactant phospholipids. We propose that the aiPLA2 activity of the enzyme is regulated through phosphorylation. Incubation of isolated rat alveolar type II cells (AECII) with PMA, a PKC (protein kinase C) agonist, had no effect on Prdx6 expression but led to ∼75% increase in aiPLA2 activity that was abolished by pretreatment of cells with the MAPK (mitogen-activated protein kinase) inhibitors, SB202190 or PD98059. Prdx6 phosphorylation after incubation of AECII with PMA was demonstrated by autoradiography after immunoprecipitation with either anti-phosphothreonine o-phosphoserine antibodies. in vitro, several active isoforms of ERK (extracellular-signal-regulated kinase) and p38 phosphorylated Prdx6, resulting in an 11-fold increase in aiPLA2 activity. The increased activity was calcium-independent and was abolished by the aiPLA2 inhibitors, surfactant protein A and hexadecyl-3-trifluorethylglycero-sn-2-phospho-methanol (MJ33). The peroxidase activity of Prdx6 was unaffected by phosphorylation. Mass spectroscopic analysis of in vitro phosphorylated Prdx6 showed a unique phosphorylation site at Thr-177 and mutation of this residue abolished protein phosphorylation and the increase in MAPK-mediated activity. These results show that the MAPKs can mediate phosphorylation of Prdx6 at Thr-177 with a consequent marked increase in its aiPLA2 activity.

scholarly journals Identification of RAS-Mitogen-Activated Protein Kinase Signaling Pathway Modulators in an ERF1 Redistribution® Screen

2006 ◽  
Vol 11 (4) ◽  
pp. 423-434 ◽  
Author(s):  
Charlotta Grånäs ◽  
Betina Kerstin Lundholt ◽  
Frosty Loechel ◽  
Hans-Christian Pedersen ◽  
Sara Petersen Bjørn ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Kinase Inhibitors ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
A Cell ◽  
Protein Kinase Signaling

The RAS-mitogen-activated protein kinase (MAPK) signaling pathway has a central role in regulating the proliferation and survival of both normal and tumor cells. This pathway has been 1 focus area for the development of anticancer drugs, resulting in several compounds, primarily kinase inhibitors, in clinical testing. The authors have undertaken a cell-based, high-throughput screen using a novel ERF1 Redistribution® assay to identify compounds that modulate the signaling pathway. The hit compounds were subsequently tested for activity in a functional cell proliferation assay designed to selectively detect compounds inhibiting the proliferation of MAPK pathway-dependent cancer cells. The authors report the identification of 2 cell membrane-permeable compounds that exhibit activity in the ERF1 Redistribution® assay and selectively inhibit proliferation of MAPK pathway-dependent malignant melanoma cells at similar potencies (IC50 =< 5 μM). These compounds have drug-like structures and are negative in RAF, MEK, and ERK in vitro kinase assays. Drugs belonging to these compound classes may prove useful for treating cancers caused by excessive MAPK pathway signaling. The results also show that cell-based, high-content Redistribution® screens can detect compounds with different modes of action and reveal novel targets in a pathway known to be disease relevant.

scholarly journals Ob receptor in rabbit ovary and leptin in vitro regulation of corpora lutea

2004 ◽  
Vol 183 (2) ◽  
pp. 279-288 ◽  
Author(s):  
Massimo Zerani ◽  
Cristiano Boiti ◽  
Danilo Zampini ◽  
Gabriele Brecchia ◽  
Cecilia Dall’Aglio ◽  
...  
Keyword(s):  
Leptin Receptor ◽  
Prostaglandin F2α ◽  
Janus Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Corpora Lutea ◽  
Positive Staining ◽  
Mitogen Activated Protein ◽  
Oxide Synthase ◽  
Camp And Cgmp

We studied leptin involvement in rabbit corpora lutea (CL) activity, and its post-transcriptional signalling pathway. The expression of leptin receptor (Ob-R) in rabbit ovary at day 9 of pseudopregnancy was evaluated by immunohistochemistry and Western blot analysis. The specificity of the Ob-R receptor antibodies was characterised by immunoprecipitation and competition with blocking peptide. Day 9 CL were incubated in vitro with leptin alone or with inhibitors of PLC (phospholipase C), PLD (phospholipase D), AC (adenylate cyclase), JAK (janus kinase), MAPK (mitogen-activated protein kinase) and both cAMP- and cGMP-specific PDE (phosphodiesterase). Prostaglandin F2α(PGF2α), PGE2 and progesterone levels were measured in the culture medium, while NOS (nitric oxide synthase) and cAMP- and cGMP- specific PDE activities were measured in CL tissue. Positive staining for Ob-R was found within the cytoplasm of large luteal cells of CL as well as in granulosa cells of follicles and oocytes. Immunoblots detected a band of about 99 kDa size in Ob-R immunoprecipitates from CL homogenates. This band was not detectable after pre-incubation of the primary antibody with the immunising leptin peptide. Leptin increased PGF2αand cAMP-specific PDE, decreased basal progesterone and did not affect PGE2 and NOS levels. Leptin used the JAK pathway in increasing PGF2α, and MAPK and cAMP-specific PDE in decreasing progesterone. This study supports a permissive luteolytic role for leptin in rabbit CL.

scholarly journals p38 Mitogen-Activated Protein Kinase Is Critical for Synergistic Induction of the FSHβ Gene by Gonadotropin-Releasing Hormone and Activin through Augmentation of c-Fos Induction and Smad Phosphorylation

2007 ◽  
Vol 21 (12) ◽  
pp. 3071-3086 ◽  
Author(s):  
Djurdjica Coss ◽  
Cameron M. Hand ◽  
Karen K. J. Yaphockun ◽  
Heather A. Ely ◽  
Pamela L. Mellon
Keyword(s):  
P38 Mapk ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Limiting Factor ◽  
Activator Protein 1 ◽  
Mapk Activity ◽  
C Terminus ◽  
Smad Phosphorylation ◽  
Mitogen Activated Protein ◽  
Smad 3

Abstract GnRH and activin independently and synergistically activate transcription of the FSH β-subunit gene, the subunit that provides specificity and is the limiting factor in the synthesis of the mature hormone. This synergistic interaction, as determined by two-way ANOVA, is specific for FSHβ and may, therefore, contribute to differential expression of the two gonadotropin hormones, which is critical for the reproductive cycle. We find that the cross-talk between the GnRH and activin signaling pathways occurs at the level of p38 MAPK, because the synergy is dependent on p38 MAPK activity, which is activated by GnRH, and activin cotreatment augments p38 activation by GnRH. Both the Smad and activator protein-1 binding sites on the FSHβ promoter are necessary and sufficient for synergy. After cotreatment, Smad 3 proteins are more highly phosphorylated on the activin-receptor signaling-dependent residues on the C terminus than with activin treatment alone, and c-Fos is more highly expressed than with GnRH treatment alone. Inhibition of p38 by either of two different inhibitors or a dominant-negative p38 kinase abrogates synergy on FSHβ expression, reduces c-Fos induction by GnRH, and prevents the further increase in c-Fos levels that occurs with cotreatment. Additionally, p38 is necessary for maximal Smad 3 C-terminal phosphorylation by activin treatment alone and for the further increase caused by cotreatment. Thus, p38 is the pivotal signaling molecule that integrates GnRH and activin interaction on the FSHβ promoter through higher induction of c-Fos and elevated Smad phosphorylation.

scholarly journals ERK Dephosphorylation through MKP1 Deacetylation by SIRT1 Attenuates RAS-Driven Tumorigenesis

Cancers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 909 ◽  
Author(s):  
Ok-Seon Kwon ◽  
Haeseung Lee ◽  
Yun-Jeong Kim ◽  
Hyuk-Jin Cha ◽  
Na-Young Song ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Cellular Proliferation ◽  
Ectopic Expression ◽  
Direct Interaction ◽  
Mitogen Activated Protein Kinase ◽  
Erk Activation ◽  
Wide Range ◽  
Mitogen Activated Protein ◽  
Dual Specific Phosphatase

The role of Situin 1 (SIRT1) in tumorigenesis is still controversial due to its wide range of substrates, including both oncoproteins and tumor suppressors. A recent study has demonstrated that SIRT1 interferes in the Kirsten rat sarcoma viral oncogene homolog (KRAS)-driven activation of the Raf-mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK pathway, thereby inhibiting tumorigenesis. However, the molecular mechanism of SIRT1 as a tumor suppressor in RAS-driven tumorigenesis has been less clearly determined. This study presents evidence that the ectopic expression of SIRT1 attenuates RAS- or MEK-driven ERK activation and reduces cellular proliferation and transformation in vitro. The attenuation of ERK activation by SIRT1 results from prompt dephosphorylation of ERK, while MEK activity remains unchanged. We identified that MKP1, a dual specific phosphatase for MAPK, was deacetylated by SIRT1. Deacetylation of MKP1 by direct interaction with SIRT1 increased the binding affinity to ERK which in turn facilitated inactivation of ERK. Taken together, these results suggest that SIRT1 would act as a tumor suppressor by modulating RAS-driven ERK activity through MKP1 deacetylation.

scholarly journals Transcriptional Repressor ERF Is a Ras/Mitogen-Activated Protein Kinase Target That Regulates Cellular Proliferation

1999 ◽  
Vol 19 (6) ◽  
pp. 4121-4133 ◽  
Author(s):  
Lionel le Gallic ◽  
Dionyssios Sgouras ◽  
Gregory Beal ◽  
George Mavrothalassitis
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Cellular Proliferation ◽  
Transcriptional Repressor ◽  
Mitogen Activated Protein Kinase ◽  
Ras Signaling ◽  
Mitogen Activated Protein ◽  
Ets Family

ABSTRACT A limited number of transcription factors have been suggested to be regulated directly by Erks within the Ras/mitogen-activated protein kinase signaling pathway. In this paper we demonstrate that ERF, a ubiquitously expressed transcriptional repressor that belongs to the Ets family, is physically associated with and phosphorylated in vitro and in vivo by Erks. This phosphorylation determines the ERF subcellular localization. Upon mitogenic stimulation, ERF is immediately phosphorylated and exported to the cytoplasm. The export is blocked by specific Erk inhibitors and is abolished when residues undergoing phosphorylation are mutated to alanine. Upon growth factor deprivation, ERF is rapidly dephosphorylated and transported back into the nucleus. Phosphorylation-defective ERF mutations suppress Ras-induced tumorigenicity and arrest the cells at the G0/G1 phase of the cell cycle. Our findings strongly suggest that ERF may be important in the control of cellular proliferation during the G0/G1 transition and that it may be one of the effectors in the mammalian Ras signaling pathway.

31 PROTOCOL OPTIMIZATION AND EVALUATION OF MATURATION PROMOTING FACTOR AND MITOGEN-ACTIVATED PROTEIN KINASE ACTIVITIES IN BOVINE CYTOPLASTS OBTAINED BY CHEMICAL ENUCLEATION TECHNIQUES

2014 ◽  
Vol 26 (1) ◽  
pp. 130
Author(s):  
N. Z. Saraiva ◽  
C. S. Oliveira ◽  
M. del Collado ◽  
M. R. de Lima ◽  
R. Vantini ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Mapk Activity ◽  
Significant Difference ◽  
Mitogen Activated Protein ◽  
Chi Squared ◽  
High Concentrations ◽  
Bovine Oocytes ◽  
Maturation Promoting Factor

Chemical enucleation using microtubule-depolymerizing drugs is an attractive procedure to simplify the enucleation process in nuclear transfer. The aim of this study was to optimize chemically assisted (CA) and chemically induced (CI) enucleation protocols using metaphase II (MII) and pre-activated bovine oocytes, respectively, and to evaluate the activity of maturation promoting factor (MPF) and mitogen-activated protein kinase (MAPK) in cytoplasts generated by these techniques. Initially, we determined the shortest effective treatment of MII and activated oocytes with 0.05 μg mL–1 demecolcine. Bovine oocytes in vitro matured (IVM) for 19 h (MII) or activated artificially with 5 μM ionomycin (5 min) and 10 μg mL–1 cycloheximide (5 h) after 26 h IVM were treated with demecolcine and samples were collected at 0, 0.25, 0.5, 1.0, 1.5, and 2.0 h of treatment. Oocytes were then stained with 10 μg mL–1 Hoechst 33342 and the protrusion or enucleation rates were determined. Next, we evaluated histone H1 and myelin basic protein (MBP) kinases, reflecting MPF and MAPK activities, respectively, in oocytes obtained from these treatments, and for that we used the method described by Kubelka et al. (2000 Biol. Reprod. 62, 292–302). Protrusion and enucleation rates were evaluated by the chi-squared (χ2) test, and MPF and MAPK activities were submitted to ANOVA and Tukey's test at 5% significance. For MII oocytes, effects of demecolcine were observed as early as 15 min, with a significant difference (P < 0.05) between control (12/112, 10.7%) and treated (33/114, 28.9%) groups in relation to protrusion rates. The largest number of protrusions was observed after 1.0 h of treatment (control: 15/113, 13.3%a; treated: 45/111, 40.5%b). In pre-activated oocytes, effects of demecolcine were also observed after 15 min, and in both techniques there were no significant differences between groups treated with demecolcine for 1.0, 1.5, or 2.0 h (CA: 40.5 to 52.5% of protrusion; CI: 35.2 to 46.7% of enucleation). In contrast to previous reports in which high concentrations of demecolcine for CA enucleation increased MPF activity, we observed no alterations in the activity of this factor at a demecolcine concentration of 0.05 μg mL–1. Activity of MAPK also did not differ significantly between the control and treated groups throughout evaluation. In the CI technique, a significant difference in MPF activity was observed after 0.5 h (70.3%) and 2.0 h of activation (39.1%), considering that the activity was 100% at the beginning of the evaluation. However, we observed no significant difference between the control and treated groups at any of the time points studied, as verified for MAPK activity. The exact effect of MPF on the nucleus in mammals is not well established. We believe that the use of low concentrations of demecolcine for short periods is less damaging to embryonic development and, until we have a better understanding of the effect of these kinases on the transferred nucleus, we recommend its use for chemical enucleation protocols in bovine. Financial support: FAPESP 2010/20744-6 and 2011/12983-3.

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