scholarly journals Nuclear translocation of tagged endogenous MPK-1/ERK denotes a subset of activation events in C. elegans development

2021 ◽  
Author(s):  
Neal R. Rasmussen ◽  
David J. Reiner
Keyword(s):  
Nuclear Translocation ◽  
Cultured Cells ◽  
Intercellular Signaling ◽  
Erk Activation ◽  
C Elegans ◽  
Extracellular Signal ◽  
Vulval Precursor Cells ◽  
Elevated Expression ◽  
Necessary And Sufficient

The extracellular signal-regulated kinase (ERK) MAP kinase is utilized downstream of Ras>Raf>MEK signaling to control activation of a wide array of targets. Activation of ERK is elevated in Ras-driven tumors and RASopathies, and is thus a target for pharmacological inhibition. Regulatory mechanisms of ERK activation have been studied extensively in vitro and in cultured cells but little in living animals. We tagged the C. elegans ERK-encoding gene, mpk-1. MPK-1 is ubiquitously expressed with elevated expression in certain contexts. We detected cytosol-to-nuclear translocation of MPK-1 in maturing oocytes and hence validated nuclear translocation as a reporter of some activation events. During patterning of vulval precursor cells, MPK-1 is necessary and sufficient for the central cell, P6.p, to assume 1˚ fate. Yet MPK-1 translocates to the nuclei of all six VPCs in a temporal and concentration gradient centered on P6.p. This observation contrasts with previous results using the ERK-nKTR reporter of substrate activation, raising questions about mechanisms and indicators of MPK-1 activation. This system and reagent promise to provide critical insights into regulation of MPK-1 activation within a complex intercellular signaling network.

scholarly journals Nuclear translocation of tagged endogenous ERK/MPK-1 MAP Kinase denotes a subset of activation events in C. elegans development

2021 ◽  
Author(s):  
Neal R. Rasmussen ◽  
David J. Reiner
Keyword(s):  
Map Kinase ◽  
Nuclear Translocation ◽  
Cultured Cells ◽  
Intercellular Signaling ◽  
Erk Activation ◽  
C Elegans ◽  
Extracellular Signal ◽  
Elevated Expression ◽  
Necessary And Sufficient

ABSTRACTThe extracellular signal-regulated kinase (ERK) MAP kinase is utilized downstream of Ras>Raf>MEK signaling to control activation of a wide array of targets. Activation of ERK is elevated in Ras-driven tumors and RASopathies, and is thus a target for pharmacological inhibition. Regulatory mechanisms of ERK activation has been studied extensively in vitro and in cultured cells but little in living animals. We used CRISPR to tag the 3’ end of the C. elegans ERK-encoding gene, mpk-1. Endogenous MPK-1 protein is ubiquitously expressed with elevated expression in certain tissues. We detected cytosol-to-nuclear translocation of MPK-1 in maturing oocytes and hence validated nuclear translocation as a reporter of some activation events. During developmental patterning of the six vulval precursor cells, MPK-1 is necessary and sufficient for the central cell, P6.p, to assume 1° fate. We observed MPK-1 to be recruited to the nuclei of all six VPCs in a temporal and concentration gradient centered on P6.p. This observation contrasts with previous results using the ERK-nKTR reporter of substrate activation, raising questions about mechanisms and indicators of MPK-1 activation. This system and reagent promise to provide critical insights into regulation of MPK-1 activation within a complex intercellular signaling network.

scholarly journals PDCD4–MAPK–NF-κB Positive Loop Simultaneously Promotes Microglia Activation and Neuron Apoptosis During Neuroinflammation

2021 ◽  
Author(s):  
Quan Chen ◽  
Hongjian Lu ◽  
Chengwei Duan ◽  
Xiangyang Zhu ◽  
Yi Zhang ◽  
...  
Keyword(s):  
Nuclear Translocation ◽  
Inflammatory Diseases ◽  
Damage Model ◽  
Pdcd4 Expression ◽  
Proapoptotic Protein ◽  
Inflammatory Activation ◽  
Elevated Expression ◽  
The Central Nervous System ◽  
Signaling Activation

Abstract Neuroinflammation and neuron injury are common features of the central nervous system (CNS) diseases. It is of great significance to identify their shared regulatory mechanisms and explore the potential therapeutic targets. Programmed cell death factor 4 (PDCD4), an apoptosis-related molecule, extensively participates in tumorigenesis and inflammatory diseases, but its expression and biological function during CNS neuroinflammation remain unclear. In the present study, utilizing the lipopolysaccharide (LPS)-induced neuroinflammation model in mice, we reported an elevated expression of PDCD4 both in injured neurons and activated microglia of the inflamed brain. A similar change in PDCD4 expression was observed in vitro in the microglial activation model. Silencing PDCD4 by shRNA significantly inhibited the phosphorylation of MAPKs (p38, ERK, and JNK), prevented the phosphorylation and nuclear translocation of NF-κB p65, and thus attenuated the LPS-induced microglial inflammatory activation. Interestingly, LPS also required the MAPK/NF-κB signaling activation to boost PDCD4 expression in microglia, indicating the presence of a positive loop. Moreover, a persistent elevation of PDCD4 expression was detected in the H2O2-induced neuronal oxidative damage model. Knocking down PDCD4 significantly inhibited the expression of proapoptotic protein BAX, suggesting the proapoptotic activity of PDCD4 in neurons. Taken together, our data indicated that PDCD4 may serve as a hub regulatory molecule that simultaneously promotes the microglial inflammatory activation and the oxidative stress-induced neuronal apoptosis within CNS. The microglial PDCD4–MAPK–NF-κB positive feedback loop may exaggerate the vicious cycle of neuroinflammation and neuronal injury and thus may become a potential therapeutic target for neuroinflammatory diseases.

Fibronectin maintains survival of mouse natural killer (NK) cells via CD11b/Src/β-catenin pathway

Blood ◽  
2009 ◽  
Vol 114 (19) ◽  
pp. 4081-4088 ◽  
Author(s):  
Ting Zhang ◽  
Shuxun Liu ◽  
Pengyuan Yang ◽  
Chaofeng Han ◽  
Jianli Wang ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Nuclear Translocation ◽  
Nk Cell ◽  
Ex Vivo ◽  
Interleukin 12 ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
B Cell Leukemia

Abstract Tissue microenvironment and stroma-derived extracellular matrix (ECM) molecules play important roles in the survival and differentiation of cells. Mouse natural killer (NK) cells usually die within 24 hours once isolated ex vivo. Exogenous cytokines such as interleukin-12 (IL-12) and IL-15 are required to maintain the survival and activity of mouse NK cells cultured in vitro. Whether and how ECM molecules such as fibronectin can support the survival of NK cells remain unknown. We demonstrate that fibronectin, just like IL-15, can maintain survival of mouse NK cells in vitro. Furthermore, we show that fibronectin binds to the CD11b on NK cells, and then CD11b recruits and activates Src. Src can directly interact with β-catenin and trigger nuclear translocation of β-catenin. The activation of β-catenin promotes extracellular signal-related kinase (ERK) phosphorylation, resulting in the increased expression of antiapoptotic protein B-cell leukemia 2 (Bcl-2), which may contribute to the maintenance of NK-cell survival. Consistently, fibronectin cannot maintain the survival of CD11b− NK cells and β-catenin–deficient NK cells in vitro, and the number of NK cells is dramatically decreased in the β-catenin–deficient mice. Therefore, fibronectin can maintain survival of mouse NK cells by activating ERK and up-regulating Bcl-2 expression via CD11b/Src/β-catenin pathway.

scholarly journals LY6K promotes glioblastoma tumorigenicity via CAV-1–mediated ERK1/2 signaling enhancement

2020 ◽  
Vol 22 (9) ◽  
pp. 1315-1326 ◽  
Author(s):  
Namratha G Sastry ◽  
Xuechao Wan ◽  
Tianzhi Huang ◽  
Angel A Alvarez ◽  
Rajendra P Pangeni ◽  
...  
Keyword(s):  
Radiation Treatment ◽  
Tumor Biology ◽  
Immunofluorescent Staining ◽  
Caveolin 1 ◽  
Extracellular Signal ◽  
Elevated Expression ◽  
Membrane Target ◽  
Patient Prognosis

Abstract Background Lymphocyte antigen 6 complex, locus K (LY6K) is a putative oncogene in various cancers. Elevated expression of LY6K is correlated with poor patient prognosis in glioblastoma (GBM). The aim of this study is to advance our understanding of the mechanism by which LY6K contributes to GBM tumor biology. Methods Bioinformatic data mining was used to investigate LY6K expression in relation to GBM clinical outcome. To understand the role of LY6K in GBM, we utilized patient-derived glioma stemlike cells (GSCs) and U87 cells and employed immunoblotting, immunofluorescent staining, radiation treatment, and orthotopic GBM xenograft models. Results Our results show that increased expression of LY6K inversely correlates with GBM patient survival. LY6K promotes tumorigenicity in GBM cells both in vitro and in vivo. The mechanism underlying this tumorigenic behavior is enhancement of extracellular signal-regulated kinase 1 and 2 (ERK1/2) signaling. Interestingly, we observed that tumor-promoting LY6K-ERK1/2 signaling is mediated by the interaction of LY6K with caveolin-1, rather than through oncogenic receptor tyrosine kinase–mediated signaling. Moreover, association of LY6K with the cell membrane is crucial for its tumorigenic functions. Finally, DNA methylation maintains LY6K silencing, and hypomethylation of the LY6K promoter increases its expression. In GSCs, ionizing radiation leads to demethylation of the LY6K promoter, thereby increasing LY6K expression and GSC resistance to radiation. Conclusions Our study highlights the importance of the contribution of LY6K to GBM tumor biology and suggests LY6K as a potential membrane target for treating GBM.

scholarly journals Mutational Analysis of an RNA Polymerase II Elongation Factor in Drosophila melanogaster

2005 ◽  
Vol 25 (17) ◽  
pp. 7803-7811 ◽  
Author(s):  
Mark A. Gerber ◽  
Ali Shilatifard ◽  
Joel C. Eissenberg
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Cultured Cells ◽  
Mutational Analysis ◽  
Elongation Factor ◽  
Regulatory Function ◽  
Polymerase Binding ◽  
Necessary And Sufficient ◽  
Elongation Activity

ABSTRACT The ELL family of proteins function in vitro as elongation factors for RNA polymerase II. Deletion studies have defined domains in mammalian ELL required for transcription elongation activity and RNA polymerase binding in vitro, for transformation of cultured cells when overexpressed, and for leukemogenesis and cell proliferation as part of a leukemic fusion protein. The goal of this study was to identify domains required for chromosome targeting and viability in the unique Drosophila ELL (dELL) protein. Here, we show that an N-terminal domain of dELL is necessary and sufficient for targeting to transcriptionally active puff sites in chromatin, supporting a role for this domain in recruiting dELL to elongating RNA polymerase II. We demonstrate that a central domain of dELL is required for rapid mobilization of ELL during the heat shock response, suggesting a regulatory function for this domain. Unexpectedly, transgenic dELL in which the N-terminal chromosome binding domain is deleted can complement the recessive lethality of mutations in ELL, suggesting that Drosophila ELL has an essential activity in development distinct from its role as an RNA polymerase II elongation factor.

scholarly journals Identification of phenolic secondary metabolites from Schotia brachypetala Sond. (Fabaceae) and demonstration of their antioxidant activities in Caenorhabditis elegans

2016 ◽  
Author(s):  
Mansour Sobeh ◽  
Esraa A ElHawary ◽  
Herbenya Peixoto ◽  
Rola M Labib ◽  
Heba Handoussa ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Caenorhabditis Elegans ◽  
Nuclear Translocation ◽  
Antioxidant Activities ◽  
In Vitro Assays ◽  
Flavonoid Glycosides ◽  
Alcoholic Extract ◽  
C Elegans

Background: Schotia brachypetala Sond. (Fabaceae) is an endemic tree of Southern Africa whose phytochemistry and pharmacology were slightly studied.The present work aimed at profiling the major phenolics compounds present in the hydro-alcoholic extract from S. brachypetala leaves (SBE) using LC/HRESI/MS/MS and NMR and prove their antioxidant capabilities using novel methods. Methods: In vitro assays; DPPH, TEAC persulfate decolorizing kinetic and FRAP assays, and in vivo assays: Caenorhabditis elegans strains maintenance, Intracellular ROS in C. elegans, Survival assay, GFP expression and Subcellular DAF-16 localization were employed to evaluate the antioxidant activity. Results: More than forty polyphenols ,including flavonoid glycosides, galloylated flavonoid glycosides, isoflavones, dihydrochalcones, procyanidins, anthocyanins, hydroxybenzoic acid derivatives, hydrolysable tannins, and traces of methylated and acetylated flavonoid derivatives were identified. Three compounds were isolated and identified from the genus Schotia for the first time, namely gallic acid, myricetin-3-O-α-L-1C4-rhamnoside and quercetin-3-O-L-1C4-rhamnoside.The tested extract was able to protect the worms against juglone induced oxidative stress and attenuate the reactive oxygen species (ROS) accumulation. SBE was also able to attenuate the levels of heat shock protein (HSP) expression. Discussion: A pronounced antioxidant activity in vivo, which can be attributed to its ability to promote the nuclear translocation of DAF-16/FOXO, the main transcription factor regulating the expression of stress response genes. The remarkable antioxidant activity in vitro and in vivo correlates to SBE rich phenolic profile.

scholarly journals Reevaluation of the role of LIP-1 as an ERK/MPK-1 dual specificity phosphatase in the C. elegans germline

2022 ◽  
Vol 119 (3) ◽  
pp. e2113649119
Author(s):  
Debabrata Das ◽  
Jacob Seemann ◽  
David Greenstein ◽  
Tim Schedl ◽  
Swathi Arur
Keyword(s):  
Failure To Rescue ◽  
Gain Of Function ◽  
Erk Activation ◽  
C Elegans ◽  
Cellular Processes ◽  
Dual Specificity ◽  
Extracellular Signal ◽  
Dual Specificity Phosphatases ◽  
Organismal Development

The fidelity of a signaling pathway depends on its tight regulation in space and time. Extracellular signal-regulated kinase (ERK) controls wide-ranging cellular processes to promote organismal development and tissue homeostasis. ERK activation depends on a reversible dual phosphorylation on the TEY motif in its active site by ERK kinase (MEK) and dephosphorylation by DUSPs (dual specificity phosphatases). LIP-1, a DUSP6/7 homolog, was proposed to function as an ERK (MPK-1) DUSP in the Caenorhabditis elegans germline primarily because of its phenotype, which morphologically mimics that of a RAS/let-60 gain-of-function mutant (i.e., small oocyte phenotype). Our investigations, however, reveal that loss of lip-1 does not lead to an increase in MPK-1 activity in vivo. Instead, we show that loss of lip-1 leads to 1) a decrease in MPK-1 phosphorylation, 2) lower MPK-1 substrate phosphorylation, 3) phenocopy of mpk-1 reduction-of-function (rather than gain-of-function) allele, and 4) a failure to rescue mpk-1–dependent germline or fertility defects. Moreover, using diverse genetic mutants, we show that the small oocyte phenotype does not correlate with increased ectopic MPK-1 activity and that ectopic increase in MPK-1 phosphorylation does not necessarily result in a small oocyte phenotype. Together, these data demonstrate that LIP-1 does not function as an MPK-1 DUSP in the C. elegans germline. Our results caution against overinterpretation of the mechanistic underpinnings of orthologous phenotypes, since they may be a result of independent mechanisms, and provide a framework for characterizing the distinct molecular targets through which LIP-1 may mediate its several germline functions.

scholarly journals Cooperative Regulation of Extracellular Signal-Regulated Kinase Activation and Cell Shape Change by Filamin A and β-Arrestins

2006 ◽  
Vol 26 (9) ◽  
pp. 3432-3445 ◽  
Author(s):  
Mark G. H. Scott ◽  
Vincenzo Pierotti ◽  
Hélène Storez ◽  
Erika Lindberg ◽  
Alain Thuret ◽  
...  
Keyword(s):  
Shape Change ◽  
Receptor Activation ◽  
Dominant Negative ◽  
Scaffolding Protein ◽  
Actin Binding ◽  
Filamin A ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal

ABSTRACT β-Arrestins (βarr) are multifunctional adaptor proteins that can act as scaffolds for G protein-coupled receptor activation of mitogen-activated protein kinases (MAPK). Here, we identify the actin-binding and scaffolding protein filamin A (FLNA) as a βarr-binding partner using Son of sevenless recruitment system screening, a classical yeast two-hybrid system, coimmunoprecipitation analyses, and direct binding in vitro. In FLNA, the βarr-binding site involves tandem repeat 22 in the carboxyl terminus. βarr binds FLNA through both its N- and C-terminal domains, indicating the presence of multiple binding sites. We demonstrate that βarr and FLNA act cooperatively to activate the MAPK extracellular signal-regulated kinase (ERK) downstream of activated muscarinic M1 (M1MR) and angiotensin II type 1a (AT1AR) receptors and provide experimental evidence indicating that this phenomenon is due to the facilitation of βarr-ERK2 complex formation by FLNA. In Hep2 cells, stimulation of M1MR or AT1AR results in the colocalization of receptor, βarr, FLNA, and active ERK in membrane ruffles. Reduction of endogenous levels of βarr or FLNA and a catalytically inactive dominant negative MEK1, which prevents ERK activation, inhibit membrane ruffle formation, indicating the functional requirement for βarr, FLNA, and active ERK in this process. Our results indicate that βarr and FLNA cooperate to regulate ERK activation and actin cytoskeleton reorganization.

scholarly journals Coordination of RNA and protein condensation by the P granule protein MEG-3

2020 ◽  
Author(s):  
Helen Schmidt ◽  
Andrea Putnam ◽  
Dominique Rasoloson ◽  
Geraldine Seydoux
Keyword(s):  
Protein Interactions ◽  
Intrinsically Disordered Protein ◽  
Protein Protein Interactions ◽  
C Elegans ◽  
Intrinsically Disordered ◽  
Disordered Protein ◽  
C Terminus ◽  
Necessary And Sufficient

ABSTRACTGerm granules are RNA-protein condensates in germ cells. The mechanisms that drive germ granule assembly are not fully understood. MEG-3 is an intrinsically-disordered protein required for germ (P) granule assembly in C. elegans. MEG-3 forms gel-like condensates on liquid condensates assembled by PGL proteins. MEG-3 is related to the GCNA family and contains an N-terminal disordered region (IDR) and a predicted ordered C-terminus featuring an HMG-like motif (HMGL). Using in vitro and in vivo experiments, we find the MEG-3 C-terminus is necessary and sufficient to build MEG-3/PGL co-condensates independent of RNA. The HMGL domain is required for high affinity MEG-3/PGL binding in vitro and for assembly of MEG-3/PGL co-condensates in vivo. The MEG-3 IDR binds RNA in vitro and is required but not sufficient to recruit RNA to P granules. Our findings suggest that P granule assembly depends in part on protein-protein interactions that drive condensation independent of RNA.

scholarly journals ERK1/2-p90RSK-mediated Phosphorylation of Na+/H+ Exchanger Isoform 1

2007 ◽  
Vol 282 (38) ◽  
pp. 28274-28284 ◽  
Author(s):  
Jing Luo ◽  
Douglas B. Kintner ◽  
Gary E. Shull ◽  
Dandan Sun
Keyword(s):  
Nuclear Translocation ◽  
Neuronal Damage ◽  
Glucose Deprivation ◽  
Mek Inhibitor ◽  
Oxygen And Glucose Deprivation ◽  
Genetic Ablation ◽  
Extracellular Signal ◽  
Nhe1 Activity ◽  
Ribosomal S6 Kinase

The function and regulation of Na+/H+ exchanger isoform 1 (NHE1) following cerebral ischemia are not well understood. In this study, we demonstrate that extracellular signal-related kinases (ERK1/2) play a role in stimulation of neuronal NHE1 following in vitro ischemia. NHE1 activity was significantly increased during 10-60 min reoxygenation (REOX) after 2-h oxygen and glucose deprivation (OGD). OGD/REOX not only increased the Vmax for NHE1 but also shifted the Km toward decreased [H+]i. These changes in NHE1 kinetics were absent when MAPK/ERK kinase (MEK) was inhibited by the MEK inhibitor U0126. There were no changes in the levels of phosphorylated ERK1/2 (p-ERK1/2) after 2 h OGD. The p-ERK1/2 level was significantly increased during 10-60 min REOX, which was accompanied by nuclear translocation. U0126 abolished REOX-induced elevation and translocation of p-ERK1/2. We further examined the ERK/90-kDa ribosomal S6 kinase (p90RSK) signaling pathways. At 10 min REOX, phosphorylated NHE1 was increased with a concurrent elevation of phosphorylation of p90RSK, a known NHE1 kinase. Inhibition of MEK activity with U0126 abolished phosphorylation of both NHE1 and p90RSK. Moreover, neuroprotection was observed with U0126 or genetic ablation or pharmacological inhibition of NHE1 following OGD/REOX. Taken together, these results suggest that activation of ERK1/2-p90RSK pathways following in vitro ischemia phosphorylates NHE1 and increases its activity, which subsequently contributes to neuronal damage.

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