76 Rasgrp4 expression in rheumatoid synovium plays a critical role via ras- mapk pathway

AbstractGermline mutations in BRAF and other components of the MAPK pathway are associated with the congenital syndromes collectively known as RASopathies. Here, we report the association of Septo-Optic Dysplasia (SOD) including hypopituitarism and Cardio-Facio-Cutaneous (CFC) syndrome in patients harbouring mutations in BRAF. Phosphoproteomic analyses demonstrate that these genetic variants are gain-of-function mutations leading to activation of the MAPK pathway. Activation of the MAPK pathway by conditional expression of the BrafV600E/+ allele, or the knock-in BrafQ241R/+ allele (corresponding to the most frequent human CFC-causing mutation, BRAF p.Q257R), leads to abnormal cell lineage determination and terminal differentiation of hormone-producing cells, causing hypopituitarism. Expression of the BrafV600E/+ allele in embryonic pituitary progenitors leads to an increased expression of cell cycle inhibitors, cell growth arrest and apoptosis, but not tumour formation. Our findings show a critical role of BRAF in hypothalamo-pituitary-axis development both in mouse and human and implicate mutations found in RASopathies as a cause of endocrine deficiencies in humans.

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Critical role of the extracellular signal–regulated kinase–MAPK pathway in osteoblast differentiation and skeletal development

The Journal of Cell Biology ◽

10.1083/jcb.200610046 ◽

2007 ◽

Vol 176 (5) ◽

pp. 709-718 ◽

Cited By ~ 337

Author(s):

Chunxi Ge ◽

Guozhi Xiao ◽

Di Jiang ◽

Renny T. Franceschi

Keyword(s):

Transcriptional Activity ◽

Mapk Pathway ◽

Skeletal Development ◽

Critical Role ◽

Dominant Negative ◽

Mitogen Activated Protein Kinase ◽

Extracellular Signal Regulated Kinase ◽

Extracellular Signal

The extracellular signal–regulated kinase (ERK)–mitogen-activated protein kinase (MAPK) pathway provides a major link between the cell surface and nucleus to control proliferation and differentiation. However, its in vivo role in skeletal development is unknown. A transgenic approach was used to establish a role for this pathway in bone. MAPK stimulation achieved by selective expression of constitutively active MAPK/ERK1 (MEK-SP) in osteoblasts accelerated in vitro differentiation of calvarial cells, as well as in vivo bone development, whereas dominant-negative MEK1 was inhibitory. The involvement of the RUNX2 transcription factor in this response was established in two ways: (a) RUNX2 phosphorylation and transcriptional activity were elevated in calvarial osteoblasts from TgMek-sp mice and reduced in cells from TgMek-dn mice, and (b) crossing TgMek-sp mice with Runx2+/− animals partially rescued the hypomorphic clavicles and undemineralized calvaria associated with Runx2 haploinsufficiency, whereas TgMek-dn; Runx2+/− mice had a more severe skeletal phenotype. This work establishes an important in vivo function for the ERK–MAPK pathway in bone that involves stimulation of RUNX2 phosphorylation and transcriptional activity.

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LncRNA MALAT1 exhibits positive effects on nucleus pulposus cell biology in vivo and in vitro by sponging miR-503

10.21203/rs.2.17571/v2 ◽

2020 ◽

Author(s):

Hongyu Zheng ◽

Tingting Wang ◽

Xiangmin Li ◽

Wei He ◽

Zhiqiang Gong ◽

...

Keyword(s):

Nucleus Pulposus ◽

Disc Degeneration ◽

Cell Biology ◽

Mapk Pathway ◽

Critical Role ◽

Mapk Signaling ◽

Positive Effects ◽

Lncrna Malat1

Abstract Background: Intervertebral disc degeneration (IDD) is characterized by the loss of nucleus pulposus cells (NPCs) and phenotypic abnormalities. Accumulating evidence suggests that long noncoding RNAs (lncRNAs) are involved in the pathogenesis of IDD. In this study, we aimed to investigate the functional effects of lncRNA MALAT1 on NPCs in IDD and the possible mechanism governing these effects. Results: We validated the decreased expression of MALAT1 in the IDD tissues, which was associated with decreased Collagen II and Aggrecan expression. In vitro, overexpressed MALAT1 could attenuate the effect of IL-1β on NPC proliferation, apoptosis, and Aggrecan degradation. In vivo, MALAT1 overexpression attenuated the severity of disc degeneration in IDD model rats. Our molecular study further demonstrated that MALAT1 could sponge miR-503, modulate the expression of miR-503, and activate downstream MAPK signaling pathways. The effects of MALAT1 on NPCs were partially reversed/aggregated by miR-503 mimics/inhibitor treatment. Conclusion: Our data suggested that the MALAT1-miR-503-MAPK pathway plays a critical role in NPCs, which may be a potential strategy for alleviating IDD.

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Aggressive Medulloblastoma-Derived Exosomal miRNAs Promote In Vitro Invasion and Migration of Tumor Cells Via Ras/MAPK Pathway

Journal of Neuropathology & Experimental Neurology ◽

10.1093/jnen/nlaa041 ◽

2020 ◽

Vol 79 (7) ◽

pp. 734-745

Author(s):

Liang-Yi Zhu ◽

Xiao-Yu Wu ◽

Xiao-Dan Liu ◽

Dan-Feng Zheng ◽

Hai-Shuang Li ◽

...

Keyword(s):

Tumor Cells ◽

Cell Lines ◽

Mapk Pathway ◽

Critical Role ◽

Sequencing Analysis ◽

Invasion And Migration ◽

In Vitro Invasion ◽

Exosomal Mirnas ◽

Group 3

Abstract Medulloblastomas (MBs) are currently divided into 4 molecular subgroups: WNT, SHH, Group 3, and Group 4. Among them, Group 3 MB has the worst prognosis, and 40%–50% of Group 3 cases are already metastatic at the time of diagnosis. Emerging evidence indicates that exosomes drive tumor invasion, but very little is known about exosomes in MBs. In this study, we initially discovered that exosomes isolated from Group 3 MB cell lines altered in vitro behaviors of a less invasive SHH MB cell line and yielded a much more aggressive phenotype. RNA-sequencing analysis revealed 7 exosomal miRNAs with markedly different expression levels between the SHH and Group 3 MB cell lines. They were all predicted to be related to the Ras/MAPK pathway according to the Kyoto Encyclopedia of Genes and Genomes data analysis. Increased expression of miR-181a-5p, miR-125b-5p, and let-7b-5p was further confirmed in Group 3 MB cells with real-time PCR and was shown to increase in vitro invasion and migratory abilities of tumor cells through the activation of ERK in Ras/MAPK pathway. Collectively, our findings suggest that exosomal miRNAs have a critical role in MB progression in vitro and might serve as diagnostic biomarkers and therapeutic targets.

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FGFR3 Associates with and Tyrosine-Phosphorylates p90RSK2, Leading to RSK2 Activation That Mediates Hematopoietic Transformation

Blood ◽

10.1182/blood.v112.11.3722.3722 ◽

2008 ◽

Vol 112 (11) ◽

pp. 3722-3722

Author(s):

Sumin Kang ◽

Shannon Elf ◽

Shaozhong Dong ◽

Taro Hitosugi ◽

Ailan Guo ◽

...

Keyword(s):

Tyrosine Kinase ◽

Tyrosine Phosphorylation ◽

Tyrosine Kinases ◽

Mapk Pathway ◽

Critical Role ◽

Ectopic Expression ◽

Alpha Helix ◽

Tail Region ◽

Murine Bone Marrow

Abstract Dysregulation of receptor tyrosine kinase FGFR3 has been implicated to play a pathogenic role in a number of human hematopoietic malignancies and solid tumors. These include t(4;14) multiple myeloma associated with ectopic expression of FGFR3 and t(4;12)(p16;p13) acute myeloid leukemia associated with expression of a constitutively activated fusion tyrosine kinase TEL-FGFR3. We recently reported that FGFR3 directly tyrosine phosphorylates p90 Ribosomal S6 Kinase2(RSK2) at Y529, which consequently regulates RSK2 activation [Kang et al, Cancer Cell 2007 Sep;12(3):201–14]. Here we identified Y707 as an additional tyrosine site of RSK2 that is phosphorylated by FGFR3. Phosphorylation at Y707 contributes to RSK2 activation, through a putative disruption of the autoinhibitory αL-helix on the C-terminus of RSK2, unlike Y529 phosphorylation that facilitates ERK binding. To elucidate the role of tyrosine phosphorylation at Y707 induced by FGFR3 in RSK2 activation, we characterized the RSK2 mutants with single Y→A and Y→F substitutions at Y707. RSK2 Y707F demonstrated decreased kinase activity, suggesting substitution of Y707 attenuates activation of RSK2 induced by FGFR3. Tyrosine phosphorylation at Y529 by FGFR3 regulates RSK2 activation by facilitating inactive ERK binding, whereas substitution of Y707 in RSK2 does not similarly attenuate inactive ERK binding to RSK2. Phosphorylation at Y707 may regulate RSK2 activation by affecting the structure of the autoinhibitory C-terminal domain of RSK2 since the Y707 is localized at the C-terminal tail region which represents a conserved putative auto-inhibitory alpha helix. Since other tyrosine kinases including FGFR1 and Src also phosphorylate RSK2 at Y529 and Y707, tyrosine phosphorylation may be a general requirement for RSK2 activation through the ERK/MAPK pathway. Together, our current and previous findings represent a paradigm for tyrosine phosphorylation-dependent regulation of serine-threonine kinases. Moreover, we found that FGFR3 interacts with RSK2 through residue W332 in the linker region of RSK2, and that this association is required for FGFR3-dependent phosphorylation of RSK2 at Y529 and Y707, and subsequent RSK2 activation. Furthermore, in a murine bone marrow transplant assay, genetic deficiency in RSK2 resulted in a significantly delayed and attenuated myeloproliferative syndrome induced by TEL-FGFR3 as compared with wild type cells, suggesting a critical role of RSK2 in FGFR3-induced hematopoietic transformation.

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Targeting Rad51 as a strategy for the treatment of melanoma cells resistant to MAPK pathway inhibition

Cell Death and Disease ◽

10.1038/s41419-020-2702-y ◽

2020 ◽

Vol 11 (7) ◽

Author(s):

Elena Makino ◽

Lisa Marie Fröhlich ◽

Tobias Sinnberg ◽

Corinna Kosnopfel ◽

Birgit Sauer ◽

...

Keyword(s):

Homologous Recombination ◽

Metastatic Melanoma ◽

Mapk Pathway ◽

Critical Role ◽

Melanoma Cells ◽

Mapk Signaling ◽

Transcriptional Level ◽

Mapk Inhibitor

Abstract Rad51 is an essential factor of the homologous recombination DNA repair pathway and therefore plays an important role in maintaining genomic stability. We show that RAD51 and other homologous recombination repair genes are overexpressed in metastatic melanoma cell lines and in melanoma patient samples, which correlates with reduced survival of melanoma patients. In addition, Rad51 expression in melanoma cells was regulated on a transcriptional level by the MAPK signaling pathway with Elk1 as the main downstream transcriptional effector. Most strikingly, melanoma cells which developed resistance towards MAPK inhibitors could be efficiently targeted by Rad51 inhibitors similar to their sensitive counterparts, leading to DNA damage, G2/M arrest and apoptosis. Furthermore, the treatment of MAPK inhibitor resistant cells with Rad51 inhibitors enhances the susceptibility of these cells for MAPK inhibitor treatment in vitro and in vivo. These data indicate that Rad51 plays a critical role in the survival of metastatic melanoma cells and is a promising target for the therapy of melanoma irrespective of its MAPK inhibitor resistance status.

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Activin Inhibits the Human Pit-1 Gene Promoter through the p38 Kinase Pathway in a Smad-Independent Manner

Endocrinology ◽

10.1210/en.2006-0444 ◽

2006 ◽

Vol 147 (9) ◽

pp. 4351-4362 ◽

Cited By ~ 24

Author(s):

Chantal de Guise ◽

Annie Lacerte ◽

Shahrzad Rafiei ◽

Rachel Reynaud ◽

Melanie Roy ◽

...

Keyword(s):

Gene Expression ◽

Pituitary Gland ◽

P38 Mapk ◽

Mapk Pathway ◽

Critical Role ◽

Gene Promoter ◽

Negative Regulator ◽

P38 Kinase ◽

P38 Mapk Pathway ◽

Lactotrope Cells

The pituitary transcription factor Pit-1 regulates hormonal production from the anterior pituitary gland. However, the mechanisms by which Pit-1 gene expression is regulated in humans are poorly understood. Activin, a member of the TGFβ superfamily, acts as a negative regulator of cell growth and prolactin gene expression in lactotrope cells. In this study, we show that activin negatively regulates the human Pit-1 gene promoter. We defined a 117-bp element within the Pit-1 promoter that is sufficient to relay these inhibitory effects. We further investigated the signaling pathways that mediate activin-induced inhibition of Pit-1 gene promoter in pituitary lactotrope cells. We found that the activin effects on Pit-1 gene regulation are Smad independent and require the p38 MAPK pathway. Specifically, blocking p38 kinase activity reverses activin-mediated inhibition of the Pit-1 gene promoter. Together, our results highlight the p38 MAPK pathway as a key regulator of activin function in pituitary lactotrope cells and further emphasizes the critical role played by activin in regulating hormonal production in the pituitary gland.

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Acquired resistance to zoledronic acid and the parallel acquisition of an aggressive phenotype are mediated by p38-MAP kinase activation in prostate cancer cells

Cell Death and Disease ◽

10.1038/cddis.2013.165 ◽

2013 ◽

Vol 4 (5) ◽

pp. e641-e641 ◽

Cited By ~ 43

Author(s):

M R Milone ◽

B Pucci ◽

F Bruzzese ◽

C Carbone ◽

G Piro ◽

...

Keyword(s):

Prostate Cancer ◽

Zoledronic Acid ◽

P38 Mapk ◽

Mapk Pathway ◽

Critical Role ◽

Resistance Index ◽

P38 Map Kinase ◽

Cross Resistance ◽

Mesenchymal Transition ◽

P38 Mapk Pathway

Abstract The nitrogen-containing bisphosphonates (N-BP) zoledronic acid (ZOL) inhibits osteoclast-mediated bone resorption, and it is used to prevent skeletal complications from bone metastases. ZOL has also demonstrated anticancer activities in preclinical models and, recently, in cancer patients, highlighting the interest in determining eventual mechanisms of resistance against this agent. In our study, we selected and characterised a resistant subline of prostate cancer (PCa) cells to better understand the mechanisms, by which tumour cells can escape the antitumour effect of ZOL. DU145R80-resistant cells were selected in about 5 months using stepwise increasing concentrations of ZOL from DU145 parental cells. DU145R80 cells showed a resistance index value of 5.5 and cross-resistance to another N-BP, pamidronate, but not to the non-nitrogen containing BP clodronate. Notably, compared with DU145 parental cells, DU145R80 developed resistance to apoptosis and anoikis, as well as overexpressed the anti-apoptotic protein Bcl-2 and oncoprotein c-Myc. Moreover, DU145R80 cells underwent epithelial to mesenchymal transition (EMT) and showed increased expression of the metalloproteases MMP-2/9, as well as increased invading capability. Interestingly, compared with DU145, DU145R80 cells also increased the gene expression and protein secretion of VEGF and the cytokines Eotaxin-1 and IL-12. At the molecular level, DU145R80 cells showed strong activation of the p38-MAPK-dependent survival pathway compared with parental sensitive cells. Moreover, using the p38-inhibitor SB203580, we completely reversed the resistance to ZOL, as well as EMT marker expression and invasion. Furthermore, SB203580 treatment reduced the expression of VEGF, Eotaxin-1, IL-12, MMP-9, Bcl-2 and c-Myc. Thus, for the first time, we demonstrate that the p38-MAPK pathway can be activated under continuous extensive exposure to ZOL in PCa cells and that the p38-MAPK pathway has a critical role in the induction of resistance, as well as in the acquisition of a more aggressive and invasive phenotype.

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Signalling Pathways Involved in the Mitogenic Effects of cAMP

Clinical Science ◽

10.1042/cs0920445 ◽

1997 ◽

Vol 92 (5) ◽

pp. 445-451 ◽

Cited By ~ 16

Author(s):

D. J. Withers

Keyword(s):

Dna Synthesis ◽

Mapk Pathway ◽

Critical Role ◽

Cell Types ◽

Mapk Cascade ◽

Mitogen Activated Protein Kinase ◽

Signalling Pathways ◽

3T3 Cells ◽

Mitogen Activated Protein ◽

Swiss 3T3

1. Elevation of intracellular cyclic AMP (cAMP) is a potent mitogenic signal for a number of cell types, including Swiss 3T3 cells, thyroid epithelial cells and the somatotroph cells of the anterior pituitary. 2. Activation of the mitogen-activated protein kinase (MAPK) cascade has been shown to underlie the mitogenic effects of many growth factors. However, the precise relationship between the mitogenic effects of cAMP and the MAPK cascade is not fully defined. 3. In Swiss 3T3 cells, elevation of cAMP did not stimulate kinases at all three levels of the MAPK cascade. Additionally, blockade of the MAPK pathway failed to inhibit cAMP-stimulated DNA synthesis. 4. Mitogenic combinations of cAMP strongly stimulated the phosphorylation and activation of the serine/threonine kinase p70 S6 kinase, p70S6K, an effect that was inhibited by rapamycin. This agent markedly inhibited cAMP-stimulated DNA synthesis, suggesting a critical role for p70S6K in cAMP mitogenic signalling. 5. Thus, multiple parallel but distinct signalling pathways may be involved in the action of mitogens. This redundancy has important implications for the pathogenesis and treatment of conditions characterized by inappropriate activation of growth factor signalling pathways.

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Nck-dependent Activation of Extracellular Signal-regulated Kinase-1 and Regulation of Cell Survival during Endoplasmic Reticulum Stress

Molecular Biology of the Cell ◽

10.1091/mbc.e03-11-0851 ◽

2004 ◽

Vol 15 (9) ◽

pp. 4248-4260 ◽

Cited By ~ 107

Author(s):

Duc Thang Nguyên ◽

Sem Kebache ◽

Ali Fazel ◽

Hetty N. Wong ◽

Sarah Jenna ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Protein Kinase ◽

Er Stress ◽

Cell Survival ◽

Mapk Pathway ◽

Critical Role ◽

Extracellular Signal Regulated Kinase ◽

Extracellular Signal

In response to stress, the endoplasmic reticulum (ER) signaling machinery triggers the inhibition of protein synthesis and up-regulation of genes whose products are involved in protein folding, cell cycle exit, and/or apoptosis. We demonstrate that the misfolding agents azetidine-2-carboxylic acid (Azc) and tunicamycin initiate signaling from the ER, resulting in the activation of Jun-N-terminal kinase, p44MAPK/extracellular signal-regulated kinase-1 (ERK-1), and p38MAPK through IRE1α-dependent mechanisms. To characterize the ER proximal signaling events involved, immuno-isolated ER membranes from rat fibroblasts treated with ER stress inducers were used to reconstitute the activation of the stress-activated protein kinase/mitogen-activate protein kinase (MAPK) pathways in vitro. This allowed us to demonstrate a role for the SH2/SH3 domain containing adaptor Nck in ERK-1 activation after Azc treatment. We also show both in vitro and in vivo that under basal conditions ER-associated Nck represses ERK-1 activation and that upon ER stress this pool of Nck dissociates from the ER membrane to allow ERK-1 activation. Moreover, under the same conditions, Nck-null cells elicit a stronger ERK-1 activation in response to Azc stress, thus, correlating with an enhanced survival phenotype. These data delineate a novel mechanism for the regulation of ER stress signaling to the MAPK pathway and demonstrate a critical role for Nck in ER stress and cell survival.

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