scholarly journals A Role for Dictyostelium RacE in Cortical Tension and Cleavage Furrow Progression

1998 ◽  
Vol 141 (2) ◽  
pp. 483-492 ◽  
Author(s):  
Noel Gerald ◽  
Jianwu Dai ◽  
H. Ping Ting-Beall ◽  
Arturo De Lozanne
Keyword(s):  
Signaling Pathways ◽  
Small Gtpase ◽  
Cleavage Furrow ◽  
Wild Type ◽  
Contractile Ring ◽  
Cortical Tension ◽  
Low Level ◽  
Cortical Cytoskeleton

The small GTPase racE is essential for cytokinesis in Dictyostelium. We found that this requirement is restricted to cells grown in suspension. When attached to a substrate, racE null cells form an actomyosin contractile ring and complete cytokinesis normally. Nonetheless, racE null cells fail completely in cytokinesis when in suspension. To understand this conditional requirement for racE, we developed a method to observe cytokinesis in suspension. Using this approach, we found that racE null cells attempt cytokinesis in suspension by forming a contractile ring and cleavage furrow. However, the cells form multiple blebs and fail in cytokinesis by regression of the cleavage furrow. We believe this phenotype is caused by the extremely low level of cortical tension found in racE null cells compared to wild-type cells. The reduced cortical tension of racE null cells is not caused by a decrease in their content of F-actin. Instead, mitotic racE null cells contain abnormal F-actin aggregates. These results suggest that racE is essential for the organization of the cortical cytoskeleton to maintain proper cortical integrity. This function of racE is independent of attachment to a substrate, but can be bypassed by other signaling pathways induced by adhesion to a substrate.

scholarly journals PLK1 plays dual roles in centralspindlin regulation during cytokinesis

2019 ◽  
Vol 218 (4) ◽  
pp. 1250-1264 ◽  
Author(s):  
Ingrid E. Adriaans ◽  
Angika Basant ◽  
Bas Ponsioen ◽  
Michael Glotzer ◽  
Susanne M.A. Lens
Keyword(s):  
Small Gtpase ◽  
The Other ◽  
Aurora B ◽  
Cleavage Furrow ◽  
Contractile Ring ◽  
Dual Roles ◽  
Early Step ◽  
Rhoa Activation ◽  
Anaphase Onset ◽  
Spindle Midzone

Cytokinesis begins upon anaphase onset. An early step involves local activation of the small GTPase RhoA, which triggers assembly of an actomyosin-based contractile ring at the equatorial cortex. Here, we delineated the contributions of PLK1 and Aurora B to RhoA activation and cytokinesis initiation in human cells. Knock-down of PRC1, which disrupts the spindle midzone, revealed the existence of two pathways that can initiate cleavage furrow ingression. One pathway depends on a well-organized spindle midzone and PLK1, while the other depends on Aurora B activity and centralspindlin at the equatorial cortex and can operate independently of PLK1. We further show that PLK1 inhibition sequesters centralspindlin onto the spindle midzone, making it unavailable for Aurora B at the equatorial cortex. We propose that PLK1 activity promotes the release of centralspindlin from the spindle midzone through inhibition of PRC1, allowing centralspindlin to function as a regulator of spindle midzone formation and as an activator of RhoA at the equatorial cortex.

scholarly journals PLK1 plays dual roles in centralspindlin regulation during cytokinesis

2018 ◽  
Author(s):  
Ingrid E. Adriaans ◽  
Angika Basant ◽  
Bas Ponsioen ◽  
Michael Glotzer ◽  
Susanne M. A. Lens
Keyword(s):  
Small Gtpase ◽  
Human Cells ◽  
The Other ◽  
Aurora B ◽  
Cleavage Furrow ◽  
Contractile Ring ◽  
Dual Roles ◽  
Local Activation ◽  
Rhoa Activation ◽  
Spindle Midzone

AbstractCytokinesis starts in anaphase with the formation of an actomyosin-based contractile ring at the equatorial cortex, which is governed by the local activation of the small GTPase RhoA. Here we delineated the contributions of PLK1 and Aurora B to RhoA activation and cytokinesis initiation in human cells. Knock-down of PRC1, which disrupts the spindle midzone, revealed the existence of two pathways that can initiate cleavage furrow ingression. One pathway depends on a well-organized spindle midzone and PLK1, while the other depends on Aurora B activity and centralspindlin oligomerization at the equatorial cortex and can operate independently of PLK1. We further show that PLK1 inhibition sequesters centralspindlin onto the spindle midzone making it unavailable for Aurora B-dependent oligomerization at the equatorial cortex. We propose that PLK1 activity promotes the release of centralspindlin from the spindle midzone through inhibition of PRC1, allowing centralspindlin to function as a regulator of spindle midzone formation and as an activator of RhoA at the equatorial cortex.

The role of anillin in meiotic cytokinesis of Drosophila males

1999 ◽  
Vol 112 (14) ◽  
pp. 2323-2334 ◽  
Author(s):  
M.G. Giansanti ◽  
S. Bonaccorsi ◽  
M. Gatti
Keyword(s):  
Narrow Band ◽  
Actin Binding ◽  
Cleavage Furrow ◽  
Ph Domain ◽  
Wild Type ◽  
Contractile Ring ◽  
Ring Assembly ◽  
Actin Binding Domain ◽  
Carboxy Terminal

Anillin is a 190 kDa actin-binding protein that concentrates in the leading edges of furrow canals during Drosophila cellularization and in the cleavage furrow of both somatic and meiotic cells. We analyzed anillin behavior during D. melanogaster spermatogenesis, and focused on the relationships between this protein and the F-actin enriched structures. In meiotic anaphases anillin concentrates in a narrow band around the cell equator. Cytological analysis of wild-type meiosis and examination of mutants defective in contractile ring assembly (chickadee and KLP3A), revealed that the formation of the anillin cortical band occurs before, and does not require the assembly of the F-actin based contractile ring. However, once the acto-myosin ring is assembled, the anillin band precisely colocalizes with this cytokinetic structure, accompanying its contraction throughout anaphase and telophase. In chickadee and KLP3A mutant ana-telophases the cortical anillin band fails to constrict, indicating that its contraction is normally driven by the cytokinetic ring. These findings, coupled with the analysis of anillin behavior in twinstar mutants, suggested a model on the role of anillin during cytokinesis. During anaphase anillin would concentrate in the cleavage furrow before the assembly of the contractile ring, binding the equatorial cortex, perhaps through its carboxy-terminal pleckstrin homology (PH) domain. Anillin would then interact with the actin filaments of the acto-myosin ring through its actin-binding domain, anchoring the contractile ring to the plasma membrane throughout cytokinesis.

scholarly journals Novel Myosin Heavy Chain Kinase Involved in Disassembly of Myosin II Filaments and Efficient Cleavage in MitoticDictyostelium Cells

2002 ◽  
Vol 13 (12) ◽  
pp. 4333-4342 ◽  
Author(s):  
Akira Nagasaki ◽  
Go Itoh ◽  
Shigehiko Yumura ◽  
Taro Q.P. Uyeda
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Myosin Ii ◽  
Kinase Domain ◽  
Cleavage Furrow ◽  
Wild Type ◽  
Daughter Cells ◽  
Cleavage Process ◽  
Interphase Cells ◽  
Myosin Heavy Chain Kinase

We have cloned a full-length cDNA encoding a novel myosin II heavy chain kinase (mhckC) from Dictyostelium. Like other members of the myosin heavy chain kinase family, themhckC gene product, MHCK C, has a kinase domain in its N-terminal half and six WD repeats in the C-terminal half. GFP-MHCK C fusion protein localized to the cortex of interphase cells, to the cleavage furrow of mitotic cells, and to the posterior of migrating cells. These distributions of GFP-MHCK C always corresponded with that of myosin II filaments and were not observed in myosin II-null cells, where GFP-MHCK C was diffusely distributed in the cytoplasm. Thus, localization of MHCK C seems to be myosin II-dependent. Cells lacking the mhckC gene exhibited excessive aggregation of myosin II filaments in the cleavage furrows and in the posteriors of the daughter cells once cleavage was complete. The cleavage process of these cells took longer than that of wild-type cells. Taken together, these findings suggest MHCK C drives the disassembly of myosin II filaments for efficient cytokinesis and recycling of myosin II that occurs during cytokinesis.

scholarly journals TRAF6-Dependent Mitogen-Activated Protein Kinase Activation Differentially Regulates the Production of Interleukin-12 by Macrophages in Response to Toxoplasma gondii

2004 ◽  
Vol 72 (10) ◽  
pp. 5662-5667 ◽  
Author(s):  
Nicola J. Mason ◽  
Jim Fiore ◽  
Takashi Kobayashi ◽  
Katherine S. Masek ◽  
Yongwon Choi ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Toxoplasma Gondii ◽  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Interleukin 12 ◽  
Wild Type ◽  
Kinase Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT The production of interleukin-12 (IL-12) is critical to the development of innate and adaptive immune responses required for the control of intracellular pathogens. Many microbial products signal through Toll-like receptors (TLR) and activate NF-κB family members that are required for the production of IL-12. Recent studies suggest that components of the TLR pathway are required for the production of IL-12 in response to the parasite Toxoplasma gondii; however, the production of IL-12 in response to this parasite is independent of NF-κB activation. The adaptor molecule TRAF6 is involved in TLR signaling pathways and associates with serine/threonine kinases involved in the activation of both NF-κB and mitogen-activated protein kinase (MAPK). To elucidate the intracellular signaling pathways involved in the production of IL-12 in response to soluble toxoplasma antigen (STAg), wild-type and TRAF6−/− mice were inoculated with STAg, and the production of IL-12(p40) was determined. TRAF6−/− mice failed to produce IL-12(p40) in response to STAg, and TRAF6−/− macrophages stimulated with STAg also failed to produce IL-12(p40). Studies using Western blot analysis of wild-type and TRAF6−/− macrophages revealed that stimulation with STAg resulted in the rapid TRAF6-dependent phosphorylation of p38 and extracellular signal-related kinase, which differentially regulated the production of IL-12(p40). The studies presented here demonstrate for the first time that the production of IL-12(p40) in response to toxoplasma is dependent upon TRAF6 and p38 MAPK.

scholarly journals The Small GTPase Rap1b: A Bidirectional Regulator of Platelet Adhesion Receptors

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Gianni Francesco Guidetti ◽  
Mauro Torti
Keyword(s):  
Cell Adhesion ◽  
Signaling Pathways ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Complex Pattern ◽  
Adhesive Properties ◽  
Adhesion Receptors ◽  
Inside Out

Integrins and other families of cell adhesion receptors are responsible for platelet adhesion and aggregation, which are essential steps for physiological haemostasis, as well as for the development of thrombosis. The modulation of platelet adhesive properties is the result of a complex pattern of inside-out and outside-in signaling pathways, in which the members of the Rap family of small GTPases are bidirectionally involved. This paper focuses on the regulation of the main Rap GTPase expressed in circulating platelets, Rap1b, downstream of adhesion receptors, and summarizes the most recent achievements in the investigation of the function of this protein as regulator of platelet adhesion and thrombus formation.

scholarly journals Mice with Deficiency of G Protein γ3 Are Lean and Have Seizures

2004 ◽  
Vol 24 (17) ◽  
pp. 7758-7768 ◽  
Author(s):  
William F. Schwindinger ◽  
Kathryn E. Giger ◽  
Kelly S. Betz ◽  
Anna M. Stauffer ◽  
Elaine M. Sunderlin ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
G Protein ◽  
Gene Targeting ◽  
Wild Type ◽  
Phenotypic Changes ◽  
Reduced Body ◽  
Γ Subunit ◽  
Body Weights ◽  
The Brain ◽  
Increased Susceptibility

ABSTRACT Emerging evidence suggests that the γ subunit composition of an individual G protein contributes to the specificity of the hundreds of known receptor signaling pathways. Among the twelve γ subtypes, γ3 is abundantly and widely expressed in the brain. To identify specific functions and associations for γ3, a gene-targeting approach was used to produce mice lacking the Gng3 gene (Gng3 −/−). Confirming the efficacy and specificity of gene targeting, Gng3 −/− mice show no detectable expression of the Gng3 gene, but expression of the divergently transcribed Bscl2 gene is not affected. Suggesting unique roles for γ3 in the brain, Gng3 −/− mice display increased susceptibility to seizures, reduced body weights, and decreased adiposity compared to their wild-type littermates. Predicting possible associations for γ3, these phenotypic changes are associated with significant reductions in β2 and αi3 subunit levels in certain regions of the brain. The finding that the Gng3 −/− mice and the previously reported Gng7 −/− mice display distinct phenotypes and different αβγ subunit associations supports the notion that even closely related γ subtypes, such as γ3 and γ7, perform unique functions in the context of the organism.

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

2001 ◽  
Vol 114 (8) ◽  
pp. 1579-1589 ◽  
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.

MO332THE IRRADIATION-INDUCED RENAL ISCHEMIC PRECONDITIONING IS BLUNTED BY THE ORAL ADMINISTRATION OF THE ANTI-ANGIOGENIC AGENT, SUNITINIB

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Badr Khbouz ◽  
François Lallemand ◽  
Pascal Rowart ◽  
Laurence Poma ◽  
Agnès Noel ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Real Time ◽  
Ischemic Preconditioning ◽  
Functional Enrichment ◽  
Whole Body ◽  
Control Group ◽  
Mrna Levels ◽  
Wild Type ◽  
Post Irradiation ◽  
Real Time Qpcr

Abstract Background and Aims Whole-body irradiation has been suggested to induce renal ischemic preconditioning (RIP) in rodent models, possibly via neo-angiogenesis. First, we comprehensively investigate the pathways involved in kidney-centered irradiation. Next, we assess the functional and structural impact of kidney-centered irradiation applied before ischemia/reperfusion (I/R) injury. Finally, we test whether Sunitinib-mediated inhibition of the neo-angiogenesis prevents irradiation-associated RIP. Method Experiment 1: Unilateral irradiation of the left kidney (8.56 Gy) was performed in male 10-week-old wild-type C57bl/6 mice (n=10). One month later, total kidney RNA was extracted from irradiated and control (n=5) mice for comparative high-throughput RNA-Seq (using BaseSpace Sequence Hub Illumina). Functional enrichment analysis was performed using Database for Annotation, Visualization and Integrated Discovery (DAVID). Experiment 2: Two x-ray beams (225Kv, 13mA) specifically targeted both kidneys for a total dose of 8.56Gy. The right kidneys were removed and harvested, and the left kidneys undergo 30-minute ischemia followed by 48-hour reperfusion (n=8) at Days 7-14-21-28 post irradiation. Experiment 3: Following the same protocol of renal I/R at Day14, 3 groups of male 10-week-old wild-type C57bl/6 mice were compared (n=8 per group): 1/ bilateral pre-irradiation; 2/ bilateral pre-irradiation and gavage with Sunitinib from Day2 to Day13; 3/ control group without irradiation or gavage. Results Experiment 1: Comparative transcriptomics showed a significant up-regulation of various signaling pathways, including angiogenesis (HMOX1) and stress response (HSPA1A, HSPA1B). Expressions of angiogenesis markers (CD31, TGFb1, HMOX1) showed an increase at both mRNA (real-time qPCR) and protein (immuno-staining) levels in irradiated kidneys compared to controls (p<0.01). Experiment 2: Following I/R, the blood urea nitrogen (BUN) and serum creatinine (SCr) levels were significantly lower in the irradiated animals compared to controls: (BUN: 86.2±6.8 vs. 454.5±27.2mg/dl; SCr: 0.1±0.01 vs. 1.7±0.2mg/dl, p<0.01). The renal infiltration by CD11b-positive cells (187±32 vs. 477±20/mm²) and F4-80 macrophages (110±22 vs. 212±25/mm²) was significantly reduced in the irradiated group. The real-time qPCR mRNA levels of the angiogenic markers, TGFb1 and CD31, were significantly increased in the irradiated group compared to controls (p<0,01). The CD31-immunostating (quantified by FiJi) was increased in irradiated mice compared to controls (p<0.01). Experiment 3: One-way analysis of variance followed by Tukey’s test showed that, following I/R, the serum levels of BUN and SCr were lower in irradiated group compared to controls (BUN: 106.1±33.6 vs. 352.2±54.3mg/dl; SCr: 0.3±0.13 vs. 1±0.2mg/dl), and in irradiated group compared to the irradiated-exposed group to Sunitinib (BUN: 106.1±33.6 vs. 408.4±54.9mg/dl; SCr: 0.3±0.12 vs. 1.5±0.3mg/dl; p<0.01). No difference was observed between the irradiated-exposed mice to Sunitinib and the controls. Conclusion Renal irradiation induces the activation of signaling pathways involved in angiogenesis in mice. Renal pre-irradiation leads to RIP, with preserved renal function and attenuated inflammation post I/R. Exposure to the anti-angiogenic drug Sunitinib post-irradiation prevents the irradiation-induced RIP.

Interactions Between Leukotriene C4 and Interleukin 13 Signaling Pathways in a Mouse Model of Airway Disease

2006 ◽  
Vol 130 (4) ◽  
pp. 440-446
Author(s):  
Jaime Chavez ◽  
Hays W. J. Young ◽  
David B. Corry ◽  
Michael W. Lieberman
Keyword(s):  
Signaling Pathways ◽  
Airway Disease ◽  
Lavage Fluid ◽  
Airway Responsiveness ◽  
Leukotriene C4 ◽  
Wild Type ◽  
Transcript Levels ◽  
Interleukin 13 ◽  
Deficient Mice ◽  
Intranasal Instillation

Abstract Context.—During an asthmatic episode, leukotriene C4 (LTC4) and interleukin 13 (IL-13) are released into the airways and are thought to be central mediators of the asthmatic response. However, little is known about how these molecules interact or affect each other's signaling pathway. Objective.—To determine if the LTC4 and IL-13 signaling pathways interact with each other's pathways. Design.—We examined airway responsiveness, cysteinyl LTs (Cys-LTs), and Cys-LT and IL-13 receptor transcript levels in wild-type mice and in mice that were deficient in γ-glutamyl leukotrienase (an enzyme that converts LTC4 to LTD4), STAT6 (signal transducer and activator of transcription 6 [a critical molecule in IL-13 signaling]), and IL-4Rα (a subunit of the IL-13 receptor). Results.—Wild-type (C57BL/129SvEv) and γ-glutamyl leukotrienase–deficient mice showed increased airway responsiveness after intranasal instillation of IL-13; similar results were observed after intranasal instillation of IL-13 or LTC4 in a second wild-type strain (BALB/c). Interleukin 13 treatment reduced levels of Cys-LTs in bronchoalveolar lavage fluid. This change was unaccompanied by changes in other arachidonic acid metabolites or in RNA transcript levels of enzymes associated with Cys-LT synthesis. Interleukin 13 treatment also increased transcript levels of the Cys-LT 1 and Cys-LT 2 receptors, while LTC4 increased transcript levels of the α1 chain of the IL-13 receptor. Furthermore, IL-4Rα–deficient mice had increased airway responsiveness to LTC4 but not to IL-13, whereas STAT6-deficient mice failed to respond to either agonist. Conclusions.—These findings indicate that LTC4 and IL-13 are dependent on or signal through STAT6 to increase airway responsiveness and that both agonists regulate expression of each other's receptors.

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