Constitutively active RAS in S. pombe causes persistent Cdc42 signalling but only transient MAPK activation

The small GTPase RAS is a signalling hub for many pathways and oncogenic human RAS mutations are assumed to over-activate all of its downstream pathways. We tested this assumption in fission yeast, where, RAS-mediated pheromone signalling (PS) activates the MAPKSpk1 and Cdc42 pathways. Unexpectedly, we found that constitutively active Ras1.G17V induced immediate but only transient MAPKSpk1 activation, whilst Cdc42 activation persisted. Immediate but transient MAPKSpk1 activation was also seen in the deletion mutant of Cdc42-GEFScd1, a Cdc42 activator. We built a mathematical model using PS negative-feedback circuits and competition between the two Ras1 effectors, MAPKKKByr2 and Cdc42-GEFScd1. The model robustly predicted the MAPKSpk1 activation dynamics of an additional 21 PS mutants. Supporting the model, we showed that a recombinant Cdc42-GEFScd1 fragment competes with MAPKKKByr2 for Ras1 binding. Our study has established a concept that the constitutively active RAS propagates differently to downstream pathways where the system prevents MAPK overactivation.

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Constitutively Active 1 RAS in S. Pombe Causes Persistent Cdc42 Signalling But Only Transient MAPK Activation

SSRN Electronic Journal ◽

10.2139/ssrn.3237000 ◽

2018 ◽

Author(s):

Emma J. Kelsall ◽

Ábel Vértesy ◽

Kees Straatman ◽

Mishal Tariq ◽

Raquel Gadea ◽

...

Keyword(s):

Mapk Activation ◽

Constitutively Active

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Activation of Cdc42 GTPase upon CRY2-Induced Cortical Recruitment Is Antagonized by GAPs in Fission Yeast

Cells ◽

10.3390/cells9092089 ◽

2020 ◽

Vol 9 (9) ◽

pp. 2089 ◽

Cited By ~ 1

Author(s):

Iker Lamas ◽

Nathalie Weber ◽

Sophie G. Martin

Keyword(s):

Fission Yeast ◽

Positive Feedback ◽

Antagonistic Activity ◽

Cell Polarization ◽

Small Gtpase ◽

Nucleotide Exchange ◽

Gtpase Activating Protein ◽

Guanine Nucleotide Exchange ◽

Nucleotide Exchange Factor ◽

Cell Architecture

The small GTPase Cdc42 is critical for cell polarization in eukaryotic cells. In rod-shaped fission yeast Schizosaccharomyces pombe cells, active GTP-bound Cdc42 promotes polarized growth at cell poles, while inactive Cdc42-GDP localizes ubiquitously also along cell sides. Zones of Cdc42 activity are maintained by positive feedback amplification involving the formation of a complex between Cdc42-GTP, the scaffold Scd2, and the guanine nucleotide exchange factor (GEF) Scd1, which promotes the activation of more Cdc42. Here, we use the CRY2-CIB1 optogenetic system to recruit and cluster a cytosolic Cdc42 variant at the plasma membrane and show that this leads to its moderate activation also on cell sides. Surprisingly, Scd2, which binds Cdc42-GTP, is still recruited to CRY2-Cdc42 clusters at cell sides in individual deletion of the GEFs Scd1 or Gef1. We show that activated Cdc42 clusters at cell sides are able to recruit Scd1, dependent on the scaffold Scd2. However, Cdc42 activity is not amplified by positive feedback and does not lead to morphogenetic changes, due to antagonistic activity of the GTPase activating protein Rga4. Thus, the cell architecture is robust to moderate activation of Cdc42 at cell sides.

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Phosphatidylinositol 3-kinase mediates integrin-dependent NF-(κ)B and MAPK activation through separate signaling pathways

Journal of Cell Science ◽

10.1242/jcs.114.8.1579 ◽

2001 ◽

Vol 114 (8) ◽

pp. 1579-1589 ◽

Cited By ~ 2

Author(s):

M. Reyes-Reyes ◽

N. Mora ◽

A. Zentella ◽

C. Rosales

Keyword(s):

Signaling Pathways ◽

Mapk Pathway ◽

Mek Inhibitor ◽

Small Gtpase ◽

Dominant Negative ◽

Dominant Negative Mutant ◽

Dependent Manner ◽

Monocytic Leukemia ◽

Monocytic Cells ◽

Mapk Activation

Integrin-mediated signals play an important but poorly understood role in regulating many leukocyte functions. In monocytes and monocytic leukemia cells, (β)1 integrin-mediated adhesion results in a strong induction of immediate-early genes that are important in inflammation. To investigate the signaling pathways from integrins in monocytic cells, THP-1 cells were stimulated via (β)1 integrins by binding to fibronectin and by crosslinking the integrins with specific monoclonal antibodies. The involvement of MAPK and PI 3-K on nuclear factor (κ)B (NF-(κ)B) activation was then analyzed. We found that integrins activated both NF-(κ)B and MAPK in a PI 3-K-dependent manner, as wortmannin and LY294002 blocked these responses. However, the specific MEK inhibitor PD98059 did not prevent integrin-mediated NF-(κ)B activation. In contrast, a dominant negative mutant of Rac completely prevented NF-(κ)B activation, but it did not affect MAPK activation. These results indicate that integrin signaling to NF-(κ)B is not mediated by the MAPK pathway, but rather by the small GTPase Rac. In addition, a dominant negative form of Ρ augmented NF-(κ)B activation and blocked MAPK activation, implying that these two pathways are in competition with each other. These data suggest that integrins activate different signaling pathways in monocytic cells. One uses PI 3-K and Rac to activate NF-(κ)B, while the other uses PI 3-K, MEK, and MAPK to activate other nuclear factors, such as Elk-1.

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Mathematical model of the cell division cycle of fission yeast

Chaos An Interdisciplinary Journal of Nonlinear Science ◽

10.1063/1.1345725 ◽

2001 ◽

Vol 11 (1) ◽

pp. 277 ◽

Cited By ~ 121

Author(s):

Bela Novak ◽

Zsuzsa Pataki ◽

Andrea Ciliberto ◽

John J. Tyson

Keyword(s):

Mathematical Model ◽

Cell Division ◽

Fission Yeast ◽

Cell Division Cycle

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A Mathematical Model of Neonatal Rat Atrial Monolayers with Constitutively Active Acetylcholine-Mediated K+ Current

PLoS Computational Biology ◽

10.1371/journal.pcbi.1004946 ◽

2016 ◽

Vol 12 (6) ◽

pp. e1004946 ◽

Cited By ~ 7

Author(s):

Rupamanjari Majumder ◽

Wanchana Jangsangthong ◽

Iolanda Feola ◽

Dirk L. Ypey ◽

Daniël A. Pijnappels ◽

...

Keyword(s):

Mathematical Model ◽

Neonatal Rat ◽

K Current ◽

Constitutively Active

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The small GTPase Rho4 is involved in controlling cell morphology and septation in fission yeast

Genes to Cells ◽

10.1046/j.1365-2443.2003.00639.x ◽

2003 ◽

Vol 8 (4) ◽

pp. 357-370 ◽

Cited By ~ 43

Author(s):

Kentaro Nakano ◽

Tadashi Mutoh ◽

Ritsuko Arai ◽

Issei Mabuchi

Keyword(s):

Fission Yeast ◽

Cell Morphology ◽

Small Gtpase

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Synthetic negative feedback circuits using engineered small RNAs

Nucleic Acids Research ◽

10.1093/nar/gky828 ◽

2018 ◽

Vol 46 (18) ◽

pp. 9875-9889 ◽

Cited By ~ 24

Author(s):

Ciarán L Kelly ◽

Andreas W K Harris ◽

Harrison Steel ◽

Edward J Hancock ◽

John T Heap ◽

...

Keyword(s):

Negative Feedback ◽

Small Rnas ◽

Feedback Circuits

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Scw1p Antagonizes the Septation Initiation Network To Regulate Septum Formation and Cell Separation in the Fission Yeast Schizosaccharomyces pombe

Eukaryotic Cell ◽

10.1128/ec.2.3.510-520.2003 ◽

2003 ◽

Vol 2 (3) ◽

pp. 510-520 ◽

Cited By ~ 13

Author(s):

Quan-Wen Jin ◽

Dannel McCollum

Keyword(s):

Schizosaccharomyces Pombe ◽

Fission Yeast ◽

Cell Separation ◽

Deletion Mutant ◽

Temperature Sensitive ◽

Growth Defects ◽

Septum Formation ◽

Primary Septum ◽

Septation Initiation Network ◽

Ring Constriction

ABSTRACT Cytokinesis in the fission yeast Schizosaccharomyces pombe is regulated by a signaling pathway termed the septation initiation network (SIN). The SIN is essential for initiation of actomyosin ring constriction and septum formation. In a screen to search for mutations that can rescue the sid2-250 SIN mutant, we obtained scw1-18. Both the scw1-18 mutant and the scw1 deletion mutant (scw1Δ mutant), have defects in cell separation. Both the scw1-18 and scw1Δ mutations rescue the growth defects of not just the sid2-250 mutant but also the other temperature-sensitive SIN mutants. Other cytokinesis mutants, such as those defective for actomyosin ring formation, are not rescued by scw1Δ. scw1Δ does not seem to rescue the SIN by restoring SIN signaling defects. However, scw1Δ may function downstream of the SIN to promote septum formation, since scw1Δ can rescue the septum formation defects of the cps1-191β-1,3-glucan synthase mutant, which is required for synthesis of the primary septum.

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