scholarly journals Ras/MAPK modifier loci revealed by eQTL in C. elegans

2017 ◽  
Author(s):  
Mark G. Sterken ◽  
Linda van Bemmelen van der Plaat ◽  
Joost A. G. Riksen ◽  
Miriam Rodriguez ◽  
Tobias Schmid ◽  
...  
Keyword(s):  
Genetic Background ◽  
Gene Expression Regulation ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
C Elegans ◽  
Oncogenic Ras ◽  
Pathway Gene ◽  
Evolutionarily Conserved ◽  
Transgenic Lines ◽  
Almost All

ABSTRACTThe oncogenic Ras/MAPK pathway is evolutionarily conserved across metazoans. Yet, almost all our knowledge on this pathway comes from studies using single genetic backgrounds, whereas mutational effects can be highly background dependent. Therefore, we lack insight in the interplay between genetic backgrounds and the Ras/MAPK-signaling pathway. Here, we used a Caenorhabditis elegans RIL population containing a gain-of-function mutation in the Ras/MAPK pathway gene let-60 and measured how gene expression regulation is affected by this mutation. We mapped eQTL and found that the majority (~73%) of the 1516 detected cis-eQTL were not specific for the let-60 mutation, whereas most (~76%) of the 898 detected trans-eQTL were associated with the let-60 mutation. We detected 6 eQTL trans-bands specific for the interaction between the genetic background and the mutation, one of which co-localized with the polymorphic Ras/MAPK modifier amx-2. Comparison between transgenic lines expressing allelic variants of amx-2 showed the involvement of amx-2 in 79% of the trans-eQTL for genes mapping to this trans-band. Together, our results have revealed loci hidden loci affecting Ras/MAPK signaling using sensitized backgrounds in C. elegans. These loci harbor putative polymorphic modifier genes that would not have been detected using mutant screens in single genetic backgrounds.

Host-mediated RNAi of a Notch-like receptor gene inMeloidogyne incognitainduces nematode resistance

Parasitology ◽  
2018 ◽  
Vol 145 (14) ◽  
pp. 1896-1906
Author(s):  
Deshika Kohli ◽  
Parameswaran Chidambaranathan ◽  
J. Prasanth Tej Kumar ◽  
Ashish Kumar Singh ◽  
Anil Kumar ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Receptor Gene ◽  
Nematode Resistance ◽  
Receptor Protein ◽  
Binding Motifs ◽  
C Elegans ◽  
Transgenic Lines ◽  
Germline Proliferation ◽  
Epidermal Growth ◽  
Almost All

AbstractGLP-1 (abnormal germline proliferation) is a Notch-like receptor protein that plays an essential role in pharyngeal development. In this study, an orthologue ofCaenorhabditis elegans glp-1was identified inMeloidogyne incognita. A computational analysis revealed that the orthologue contained almost all the domains present in theC. elegansgene: specifically, the LIN-12/Notch repeat, the ankyrin repeat, a transmembrane domain and different ligand-binding motifs were present in orthologue, but the epidermal growth factor-like motif was not observed. An expression analysis showed differential expression ofglp-1throughout the life cycle ofM. incognita, with relatively higher expression in the egg stage. To evaluate the silencing efficacy ofMi-glp-1, transgenicArabidopsisplants carrying double-stranded RNA constructs ofglp-1were generated, and infection of these plants withM. incognitaresulted in a 47–50% reduction in the numbers of galls, females and egg masses. Females obtained from the transgenic RNAi lines exhibited 40–60% reductions in the transcript levels of the targetedglp-1gene compared with females isolated from the control plants. Second-generation juveniles (J2s), which were descendants of the infected females from the transgenic lines, showed aberrant phenotypes. These J2s exhibited a significant decrease in the overall distance from the stylet to the metacorpus region, and this effect was accompanied by disruption around the metacorporeal bulb of the pharynx. The present study suggests a role for this gene in organ (pharynx) development during embryogenesis inM. incognitaand its potential use as a target in the management of nematode infestations in plants.

scholarly journals Oncogenic RAS sensitizes cells to drug-induced replication stress via transcriptional silencing of P53

2021 ◽  
Author(s):  
Hendrika Alida Segeren ◽  
Elsbeth A van Liere ◽  
Frank M Riemers ◽  
Alain de Bruin ◽  
Bart Westendorp
Keyword(s):  
Cancer Cells ◽  
Transcriptional Control ◽  
Target Genes ◽  
Mapk Pathway ◽  
Transcriptional Response ◽  
Replication Stress ◽  
Mapk Signaling ◽  
S Phase ◽  
Drug Induced ◽  
Oncogenic Ras

Cancer cells often experience high basal levels of DNA replication stress (RS), for example due to hyperactivation of oncoproteins like MYC or RAS. Therefore, cancer cells are considered to be sensitive to drugs that exacerbate the level of RS or block the intra S-phase checkpoint. Consequently, RS-inducing drugs including ATR and CHK1 inhibitors are used or evaluated as anti-cancer therapies. However, drug resistance and lack of biomarkers predicting therapeutic efficacy limit efficient use. This raises the question what determines sensitivity of individual cancer cells to RS. Here, we report that oncogenic RAS does not only enhance the sensitivity to ATR/CHK1 inhibitors by directly causing RS. Instead, we observed that HRASG12V dampens the activation of the P53-dependent transcriptional response to drug-induced RS, which in turn confers sensitivity to RS. We demonstrate that inducible expression of HRASG12V sensitized retina pigment epithelial (RPE-hTERT) as well as osteosarcoma (U2OS) cells to ATR and CHK1 inhibitors. Using RNA-sequencing of FACS-sorted cells we discovered that P53 signaling is the sole transcriptional response to RS. However, oncogenic RAS attenuates the transcription of P53 and its target genes. Accordingly, live cell imaging showed that HRASG12V exacerbates RS in S/G2-phase, which could be rescued by stabilization of P53. Thus, our results demonstrate that transcriptional control of P53 is a prime determinant in the response to ATR/CHK1 inhibitors and show that hyperactivation of the MAPK pathway impedes this response. Our findings suggest that the level of oncogenic MAPK signaling could predict sensitivity to intra-S-phase inhibition in cancers with intact P53.

scholarly journals Post-transcriptional Down-regulation of ROCKI/Rho-kinase through an MEK-dependent Pathway Leads to Cytoskeleton Disruption in Ras-transformed Fibroblasts

2002 ◽  
Vol 13 (1) ◽  
pp. 336-347 ◽  
Author(s):  
Geraldine Pawlak ◽  
David M. Helfman
Keyword(s):  
Mapk Pathway ◽  
Rho Kinase ◽  
Mapk Signaling ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Cell Junctions ◽  
Lim Kinase ◽  
Oncogenic Ras ◽  
Cytoskeleton Disruption ◽  
Kinase Expression

Transformation by oncogenic Ras profoundly alters actin cytoskeleton organization. We investigated Ras-dependent signaling pathways involved in cytoskeleton disruption by transfecting normal rat kidney (NRK) cells with different Ras mutants. RasV12S35, a mutant known to activate specifically the Raf/MAPK pathway, led to stress fiber and focal contact disruption, whereas the adherens junctions remained intact. Next, we found that pharmacological inhibition of MEK was sufficient to restore the cytoskeletal defects of ras-transformed NRK cells, including assembly of stress fibers and focal contacts, but it did not induce reorganization of the cell-cell junctions. Investigating the mechanism underlying this phenotypic reversion, we found that the sustained MAPK signaling resulting from Ras-transformation down-regulated the expression of ROCKI and Rho-kinase, two-Rho effectors required for stress fiber formation, at the post-transcriptional level. On MEK inhibition, ROCKI/Rho-kinase expression and cofilin phosphorylation were increased, demonstrating that the Rho-kinase/LIM-kinase/cofilin pathway was functionally restored. Finally, using dominant negative or constitutively active mutants, we demonstrated that expression of ROCKI/Rho-kinase was both necessary and sufficient to promote cytoskeleton reorganization in NRK/ras cells. These findings further establish the Ras/MAPK pathway as the critical pathway involved in cytoskeleton disruption during Ras-transformation, and they suggest a new mechanism, involving alteration in ROCKI/Rho-kinase expression, by which oncogenic Ras can specifically target the actin-based cytoskeleton and achieve morphological transformation of the cells.

scholarly journals Co-occurring alterations in the RAS-MAPK pathway limit response to MET inhibitor treatment in MET exon 14 skipping mutation positive lung cancer

2018 ◽  
Author(s):  
Julia K. Rotow ◽  
Philippe Gui ◽  
Wei Wu ◽  
Victoria M. Raymond ◽  
Richard B. Lanman ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Preclinical Model ◽  
Sequencing Analysis ◽  
Advanced Stage ◽  
Acquired Drug Resistance ◽  
Therapy Strategy ◽  
Pathway Gene ◽  
Tki Treatment

AbstractPURPOSEWhile patients with advanced-stage non-small cell lung cancers (NSCLCs) harboring MET exon 14 skipping mutations (METex14) often benefit from MET tyrosine kinase inhibitor (TKI) treatment, clinical benefit is limited by primary and acquired drug resistance. The molecular basis for this resistance remains incompletely understood.METHODSTargeted sequencing analysis was performed on cell-free circulating tumor DNA obtained from 289 patients with advanced-stage METex14-mutated NSCLC.RESULTSProminent co-occurring RAS-MAPK pathway gene alterations (e.g. in KRAS, NF1) were detected in NSCLCs with METex14 skipping alterations as compared to EGFR-mutated NSCLCs. There was an association between decreased MET TKI treatment response and RAS-MAPK pathway co-occurring alterations. In a preclinical model expressing a canonical METex14 mutation, KRAS overexpression or NF1 downregulation hyperactivated MAPK signaling to promote MET TKI resistance. This resistance was overcome by co-treatment with crizotinib and the MEK inhibitor trametinib.CONCLUSIONOur study provides a genomic landscape of co-occurring alterations in advanced-stage METex14-mutated NSCLC and suggests a potential combination therapy strategy targeting MAPK pathway signaling to enhance clinical outcomes.

scholarly journals Physiological starvation increases EGF-Ras-MAPK pathway activity during C. elegans vulval induction

2018 ◽  
Author(s):  
Stéphanie Grimbert ◽  
Amhed Missael Vargas Velazquez ◽  
Christian Braendle
Keyword(s):  
Cell Fate ◽  
Mapk Pathway ◽  
Sensory System ◽  
Notch Pathway ◽  
Past Research ◽  
Mapk Signaling ◽  
Peptide Transporter ◽  
Nutrient Deprivation ◽  
C Elegans ◽  
Mutant Phenotypes

AbstractStudying how molecular pathways respond to ecologically relevant environmental variation is fundamental to understand organismal development and its evolution. Here we characterize how starvation modulates Caenorhabditis elegans vulval cell fate patterning – an environmentally sensitive process, with a nevertheless robust output. Past research has shown many vulval mutants affecting EGF-Ras-MAPK, Delta-Notch and Wnt pathways to be suppressed by environmental factors, such as starvation. Here we aimed to resolve previous, seemingly contradictory, observations on how starvation modulates levels of vulval induction. Using the strong starvation suppression of the Vulvaless phenotype of lin-3/egf reduction-of-function mutations as an experimental paradigm, we first tested for a possible involvement of the sensory system in relaying starvation signals to affect vulval induction: mutation of various sensory inputs, DAF-2/Insulin or DAF-7/TGF-β signaling did not abolish lin-3(rf) starvation suppression. In contrast, nutrient deprivation induced by mutation of the intestinal peptide transporter gene pept-1 or the TOR pathway component rsks-1 (the orthologue of mammalian P70S6K) very strongly suppressed lin-3(rf) mutant phenotypes. Therefore, physiologically starved animals induced by these mutations tightly recapitulated the effects of external starvation on vulval induction. While both starvation and pept-1 RNAi were sufficient to increase Ras and Notch pathway activities in vulval cells, the highly penetrant Vulvaless phenotype of a tissue-specific null allele of lin-3 was not suppressed by either condition. This and additional results indicate that partial lin-3 expression is required for starvation to affect vulval induction. These results suggest a cross-talk between nutrient deprivation, TOR-S6K and EGF-Ras-MAPK signaling during C. elegans vulval induction.

scholarly journals Evolutionarily conserved regulation of immunity by the splicing factor RNP-6/PUF60

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Chun Kew ◽  
Wenming Huang ◽  
Julia Fischer ◽  
Raja Ganesan ◽  
Nirmal Robinson ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Bacterial Pathogen ◽  
Active Role ◽  
Suppressive Effect ◽  
Mapk Signaling ◽  
Splicing Factor ◽  
Dependent Manner ◽  
Loss Of Function ◽  
C Elegans ◽  
Evolutionarily Conserved

Splicing is a vital cellular process that modulates important aspects of animal physiology, yet roles in regulating innate immunity are relatively unexplored. From genetic screens in C. elegans, we identified splicing factor RNP-6/PUF60 whose activity suppresses immunity, but promotes longevity, suggesting a tradeoff between these processes. Bacterial pathogen exposure affects gene expression and splicing in a rnp-6 dependent manner, and rnp-6 gain and loss-of-function activities reveal an active role in immune regulation. Another longevity promoting splicing factor, SFA-1, similarly exerts an immuno-suppressive effect, working downstream or parallel to RNP-6. RNP-6 acts through TIR-1/PMK-1/MAPK signaling to modulate immunity. The mammalian homolog, PUF60, also displays anti-inflammatory properties, and its levels swiftly decrease after bacterial infection in mammalian cells, implying a role in the host response. Altogether our findings demonstrate an evolutionarily conserved modulation of immunity by specific components of the splicing machinery.

scholarly journals Haploinsufficiency of RREB1 causes a Noonan-like RASopathy via epigenetic reprogramming of RAS-MAPK pathway genes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Oliver A. Kent ◽  
Manipa Saha ◽  
Etienne Coyaud ◽  
Helen E. Burston ◽  
Napoleon Law ◽  
...  
Keyword(s):  
Mapk Pathway ◽  
Mapk Signaling ◽  
Epigenetic Reprogramming ◽  
Gene Promoters ◽  
Pathway Gene ◽  
Element Binding Protein ◽  
Molecular Etiology ◽  
The Common ◽  
Spectrum Disorders ◽  
Responsive Element

Abstract RAS-MAPK signaling mediates processes critical to normal development including cell proliferation, survival, and differentiation. Germline mutation of RAS-MAPK genes lead to the Noonan-spectrum of syndromes. Here, we present a patient affected by a 6p-interstitial microdeletion with unknown underlying molecular etiology. Examination of 6p-interstitial microdeletion cases reveals shared clinical features consistent with Noonan-spectrum disorders including short stature, facial dysmorphia and cardiovascular abnormalities. We find the RAS-responsive element binding protein-1 (RREB1) is the common deleted gene in multiple 6p-interstitial microdeletion cases. Rreb1 hemizygous mice display orbital hypertelorism and cardiac hypertrophy phenocopying the human syndrome. Rreb1 haploinsufficiency leads to sensitization of MAPK signaling. Rreb1 recruits Sin3a and Kdm1a to control H3K4 methylation at MAPK pathway gene promoters. Haploinsufficiency of SIN3A and mutations in KDM1A cause syndromes similar to RREB1 haploinsufficiency suggesting genetic perturbation of the RREB1-SIN3A-KDM1A complex represents a new category of RASopathy-like syndromes arising through epigenetic reprogramming of MAPK pathway genes.

scholarly journals Brassinin Inhibits Proliferation in Human Liver Cancer Cells via Mitochondrial Dysfunction

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 332
Author(s):  
Taeyeon Hong ◽  
Jiyeon Ham ◽  
Jisoo Song ◽  
Gwonhwa Song ◽  
Whasun Lim
Keyword(s):  
Mitochondrial Dysfunction ◽  
Cancer Cells ◽  
Cell Lines ◽  
Mapk Pathway ◽  
Mapk Signaling ◽  
Nuclear Antigen ◽  
Cruciferous Vegetable ◽  
Antiproliferative Effects ◽  
Hep3b Cells ◽  
Human Liver Cancer Cells

Brassinin is a phytochemical derived from Chinese cabbage, a cruciferous vegetable. Brassinin has shown anticancer effects on prostate and colon cancer cells, among others. However, its mechanisms and effects on hepatocellular carcinoma (HCC) have not been elucidated yet. Our results confirmed that brassinin exerted antiproliferative effects by reducing proliferating cell nuclear antigen (PCNA) activity, a proliferation indicator and inducing cell cycle arrest in human HCC (Huh7 and Hep3B) cells. Brassinin also increased mitochondrial Ca2+ levels and depolarized the mitochondrial membrane in both Huh7 and Hep3B cells. Moreover, brassinin generated high amounts of reactive oxygen species (ROS) in both cell lines. The ROS scavenger N-acetyl-L-cysteine (NAC) inhibited this brassinin-induced ROS production. Brassinin also regulated the AKT and mitogen-activated protein kinases (MAPK) signaling pathways in Huh7 and Hep3B cells. Furthermore, co-administering brassinin and pharmacological inhibitors for JNK, ERK1/2 and P38 decreased cell proliferation in both HCC cell lines more than the pharmacological inhibitors alone. Collectively, our results demonstrated that brassinin exerts antiproliferative effects via mitochondrial dysfunction and MAPK pathway regulation on HCC cells.

scholarly journals Antimetastatic Effects of Sesamin on Human Head and Neck Squamous Cell Carcinoma through Regulation of Matrix Metalloproteinase-2

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2248 ◽  
Author(s):  
Jian-Ming Chen ◽  
Pei-Yin Chen ◽  
Chia-Chieh Lin ◽  
Ming-Chang Hsieh ◽  
Jen-Tsun Lin
Keyword(s):  
Oral Cancer ◽  
Matrix Metalloproteinase ◽  
Head And Neck ◽  
Mapk Pathway ◽  
Human Head ◽  
Mapk Signaling ◽  
Matrix Metalloproteinase 2 ◽  
Migration And Invasion ◽  
Dependent Manner

Background: Sesamin is a lignin present in sesame oil from the bark of Zanthoxylum spp. Sesamin reportedly has anticarcinogenic potential and exerts anti-inflammatory effects on several tumors. Hypothesis/Purpose: However, the effect of sesamin on metastatic progression in human head and neck squamous carcinoma (HNSCC) remains unknown in vitro and in vivo; hence, we investigated the effect of sesamin on HNSCC cells in vitro. Methods and Results: Sesamin-treated human oral cancer cell lines FaDu, HSC-3, and Ca9-22 were subjected to a wound-healing assay. Furthermore, Western blotting was performed to assess the effect of sesamin on the expression levels of matrix metalloproteinase (MMP)-2 and proteins of the MAPK signaling pathway, including p-ERK1/2, P-p38, and p-JNK1/2. In addition, we investigated the association between MMP-2 expression and the MAPK pathway in sesamin-treated oral cancer cells. Sesamin inhibited cell migration and invasion in FaDu, Ca9-22, and HSC-3 cells and suppressed MMP-2 at noncytotoxic concentrations (0 to 40 μM). Furthermore, sesamin significantly reduced p38 MAPK and JNK phosphorylation in a dose-dependent manner in FaDu and HSC-3 cells. Conclusions: These results indicate that sesamin suppresses the migration and invasion of HNSCC cells by regulating MMP-2 and is thus a potential antimetastatic agent for treating HNSCC.

scholarly journals C. elegans discriminates colors to guide foraging

Science ◽  
2021 ◽  
Vol 371 (6533) ◽  
pp. 1059-1063 ◽  
Author(s):  
D. Dipon Ghosh ◽  
Dongyeop Lee ◽  
Xin Jin ◽  
H. Robert Horvitz ◽  
Michael N. Nitabach
Keyword(s):  
Stress Response ◽  
Cellular Stress ◽  
Color Discrimination ◽  
Cellular Stress Response ◽  
Blue Pigment ◽  
Natural Environments ◽  
C Elegans ◽  
Evolutionarily Conserved ◽  
Foraging Decisions ◽  
Light Guides

Color detection is used by animals of diverse phyla to navigate colorful natural environments and is thought to require evolutionarily conserved opsin photoreceptor genes. We report that Caenorhabditis elegans roundworms can discriminate between colors despite the fact that they lack eyes and opsins. Specifically, we found that white light guides C. elegans foraging decisions away from a blue-pigment toxin secreted by harmful bacteria. These foraging decisions are guided by specific blue-to-amber ratios of light. The color specificity of color-dependent foraging varies notably among wild C. elegans strains, which indicates that color discrimination is ecologically important. We identified two evolutionarily conserved cellular stress response genes required for opsin-independent, color-dependent foraging by C. elegans, and we speculate that cellular stress response pathways can mediate spectral discrimination by photosensitive cells and organisms—even by those lacking opsins.

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