scholarly journals Genetic suppression of defective profilin by attenuated Myosin II reveals a potential role for Myosin II in actin dynamics in vivo in fission yeast

2020 ◽  
Vol 31 (19) ◽  
pp. 2107-2114 ◽  
Author(s):  
Paola Zambon ◽  
Saravanan Palani ◽  
Shekhar Sanjay Jadhav ◽  
Pananghat Gayathri ◽  
Mohan K. Balasubramanian
Keyword(s):  
Fission Yeast ◽  
Double Mutant ◽  
Potential Role ◽  
Myosin Ii ◽  
Model Organism ◽  
Actin Dynamics ◽  
Mutant Analysis ◽  
Genetic Suppression

This work reveals an in vivo role for Myosin II in actin dynamics, potentially in its disassembly and turnover. The work uses double mutant analysis to arrive at this conclusion using the fission yeast as a model organism.

scholarly journals Tropomyosin and Myosin-II Cellular Levels Promote Actomyosin Ring Assembly in Fission Yeast

2010 ◽  
Vol 21 (6) ◽  
pp. 989-1000 ◽  
Author(s):  
Benjamin C. Stark ◽  
Thomas E. Sladewski ◽  
Luther W. Pollard ◽  
Matthew Lord
Keyword(s):  
Motor Activity ◽  
Atpase Activity ◽  
Fission Yeast ◽  
Actin Filaments ◽  
Myosin Ii ◽  
Bound State ◽  
Contractile Ring ◽  
Ring Assembly

Myosin-II (Myo2p) and tropomyosin are essential for contractile ring formation and cytokinesis in fission yeast. Here we used a combination of in vivo and in vitro approaches to understand how these proteins function at contractile rings. We find that ring assembly is delayed in Myo2p motor and tropomyosin mutants, but occurs prematurely in cells engineered to express two copies of myo2. Thus, the timing of ring assembly responds to changes in Myo2p cellular levels and motor activity, and the emergence of tropomyosin-bound actin filaments. Doubling Myo2p levels suppresses defects in ring assembly associated with a tropomyosin mutant, suggesting a role for tropomyosin in maximizing Myo2p function. Correspondingly, tropomyosin increases Myo2p actin affinity and ATPase activity and promotes Myo2p-driven actin filament gliding in motility assays. Tropomyosin achieves this by favoring the strong actin-bound state of Myo2p. This mode of regulation reflects a role for tropomyosin in specifying and stabilizing actomyosin interactions, which facilitates contractile ring assembly in the fission yeast system.

scholarly journals Cytokine Production and Function in c-mpl–Deficient Mice: No Physiologic Role for Interleukin-3 in Residual Megakaryocyte and Platelet Production

Blood ◽  
1998 ◽  
Vol 91 (8) ◽  
pp. 2745-2752 ◽  
Author(s):  
Timothy Gainsford ◽  
Andrew W. Roberts ◽  
Shinya Kimura ◽  
Donald Metcalf ◽  
Glenn Dranoff ◽  
...  
Keyword(s):  
Leukemia Inhibitory Factor ◽  
Double Mutant ◽  
Potential Role ◽  
Cytokine Production ◽  
Genetic Defects ◽  
Platelet Production ◽  
And Function ◽  
Physiologic Role ◽  
Deficient Mice

Mice lacking thrombopoietin (TPO), or its receptor c-Mpl, display defective megakaryocyte and platelet development and deficiencies in progenitor cells of multiple hematopoietic lineages. The contribution of alternative cytokines to thrombopoiesis in the absence of TPO signalling was examined in mpl−/− mice. Analysis of serum and organ-conditioned media showed no evidence of a compensatory overproduction of megakaryocytopoietic cytokines. However, consistent with a potential role in vivo, when injected intompl−/− mice, interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) retained the capacity to elevate megakaryocytes and their progenitors in hematopoietic tissues and increase circulating platelet numbers. However, double mutant mice bred to carry genetic defects both in c-Mpl and IL-3 or the alpha chain of the IL-3 receptor, displayed no greater deficiencies in megakaryocytes or platelets than mpl-deficient animals, suggesting absence of a physiologic role for IL-3 in the residual megakaryocytopoiesis and platelet production in these mice.

scholarly journals Phagocytic 'teeth' and myosin-II 'jaw' power target constriction during phagocytosis

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Daan Vorselen ◽  
Sarah R Barger ◽  
Yifan Wang ◽  
Wei Cai ◽  
Julie A Theriot ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Traction Force ◽  
Light Sheet ◽  
Force Generation ◽  
Actin Dynamics ◽  
Force Microscopy ◽  
Light Sheet Microscopy ◽  
Macrophage Phagocytosis ◽  
Actin Protrusions

Phagocytosis requires rapid actin reorganization and spatially controlled force generation to ingest targets ranging from pathogens to apoptotic cells. How actomyosin activity directs membrane extensions to engulf such diverse targets remains unclear. Here, we combine lattice light-sheet microscopy (LLSM) with microparticle traction force microscopy (MP-TFM) to quantify actin dynamics and subcellular forces during macrophage phagocytosis. We show that spatially localized forces leading to target constriction are prominent during phagocytosis of antibody-opsonized targets. This constriction is largely driven by Arp2/3-mediated assembly of discrete actin protrusions containing myosin 1e and 1f ('teeth') that appear to be interconnected in a ring-like organization. Contractile myosin-II activity contributes to late-stage phagocytic force generation and progression, supporting a specific role in phagocytic cup closure. Observations of partial target eating attempts and sudden target release via a popping mechanism suggest that constriction may be critical for resolving complex in vivo target encounters. Overall, our findings present a phagocytic cup-shaping mechanism that is distinct from cytoskeletal remodeling in 2D cell motility and may contribute to mechanosensing and phagocytic plasticity.

scholarly journals Tol1, a Fission Yeast Phosphomonoesterase, Is an In Vivo Target of Lithium, and Its Deletion Leads to Sulfite Auxotrophy

2000 ◽  
Vol 182 (13) ◽  
pp. 3619-3625 ◽  
Author(s):  
Rumi Miyamoto ◽  
Reiko Sugiura ◽  
Shinya Kamitani ◽  
Tomoko Yada ◽  
Yabin Lu ◽  
...  
Keyword(s):  
Cell Growth ◽  
Fission Yeast ◽  
Bipolar Affective Disorder ◽  
Model Organism ◽  
Yeast Cells ◽  
Growth Defect ◽  
Inositol Polyphosphate ◽  
Functional Conservation ◽  
High Concentrations

ABSTRACT Lithium is the drug of choice for the treatment of bipolar affective disorder. The identification of an in vivo target of lithium in fission yeast as a model organism may help in the understanding of lithium therapy. For this purpose, we have isolated genes whose overexpression improved cell growth under high LiCl concentrations. Overexpression of tol1 +, one of the isolated genes, increased the tolerance of wild-type yeast cells for LiCl but not for NaCl. tol1 + encodes a member of the lithium-sensitive phosphomonoesterase protein family, and it exerts dual enzymatic activities, 3′(2′),5′-bisphosphate nucleotidase and inositol polyphosphate 1-phosphatase. tol1 +gene-disrupted cells required high concentrations of sulfite in the medium for growth. Consistently, sulfite repressed the sulfate assimilation pathway in fission yeast. However,tol1 + gene-disrupted cells could not fully recover from their growth defect and abnormal morphology even when the medium was supplemented with sulfite, suggesting the possible implication of inositol polyphosphate 1-phosphatase activity for cell growth and morphology. Given the remarkable functional conservation of the lithium-sensitive dual-specificity phosphomonoesterase between fission yeast and higher-eukaryotic cells during evolution, it may represent a likely in vivo target of lithium action across many species.

scholarly journals Phagocytic 'teeth' and myosin-II 'jaw' power target constriction during phagocytosis

2021 ◽  
Author(s):  
Daan Vorselen ◽  
Sarah R. Barger ◽  
Yifan Wang ◽  
Wei Cai ◽  
Julie A. Theriot ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Traction Force ◽  
Light Sheet ◽  
Force Generation ◽  
Actin Dynamics ◽  
Force Microscopy ◽  
Light Sheet Microscopy ◽  
Macrophage Phagocytosis ◽  
Actin Protrusions

Phagocytosis requires rapid actin reorganization and spatially controlled force generation to ingest targets ranging from pathogens to apoptotic cells. How actomyosin activity directs membrane extensions to engulf such diverse targets remains unclear. Here, we combine lattice light-sheet microscopy (LLSM) with microparticle traction force microscopy (MP-TFM) to quantify actin dynamics and subcellular forces during macrophage phagocytosis. We show that spatially localized forces leading to target constriction are prominent during phagocytosis of antibody-opsonized targets. This constriction is largely mediated by Arp2/3-mediated assembly of discrete actin protrusions containing myosin 1e and 1f ('teeth') that are interconnected in a ring-like organization. Contractile myosin-II activity contributes to late-stage phagocytic force generation and progression, suggesting a specific role in phagocytic cup closure. Observations of partial target eating attempts and sudden target release via a popping mechanism suggest that constriction may be critical for resolving complex in vivo target encounters. Overall, our findings suggest a phagocytic cup-shaping mechanism that is distinct from cytoskeletal remodeling in 2D cell motility and may contribute to mechanosensing and phagocytic plasticity.

scholarly journals Hsp90 Protein in Fission Yeast Swo1p and UCS Protein Rng3p Facilitate Myosin II Assembly and Function

2005 ◽  
Vol 4 (3) ◽  
pp. 567-576 ◽  
Author(s):  
Mithilesh Mishra ◽  
Ventris M. D'souza ◽  
Kai Chen Chang ◽  
Yinyi Huang ◽  
Mohan K. Balasubramanian
Keyword(s):  
Fission Yeast ◽  
Fluorescent Protein ◽  
Myosin Head ◽  
Genetic Interaction ◽  
Synthetic Lethality ◽  
Myosin Ii ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Domain Protein

ABSTRACT The F-actin-based molecular motor myosin II is involved in a variety of cellular processes such as muscle contraction, cell motility, and cytokinesis. In recent years, a family of myosin II-specific cochaperones of the UCS family has been identified from work with yeasts, fungi, worms, and humans. Biochemical analyses have shown that a complex of Hsp90 and the Caenorhabditis elegans UCS domain protein UNC-45 prevent myosin head aggregation, thereby allowing it to assume a proper structure. Here we demonstrate that a temperature-sensitive mutant of the fission yeast Hsp90 (Swo1p), swo1-w1, is defective in actomyosin ring assembly at the restrictive temperature. Two alleles of swo1, swo1-w1 and swo1-26, showed synthetic lethality with a specific mutant allele of the fission yeast type II myosin head, myo2-E1, but not with two other mutant alleles of myo2 or with mutations affecting 14 other genes important for cytokinesis. swo1-w1 also showed a strong genetic interaction with rng3-65, a gene encoding a mutation in the fission yeast UCS domain protein Rng3p, which has previously been shown to be important for myosin II assembly. A similar deleterious effect was found when myo2-E1, swo1-w1, and rng3-65 were pharmacologically treated with geldanamycin to partially inhibit Hsp90 function. Interestingly, Swo1p-green fluorescent protein is detected at the improperly assembled actomyosin rings in myo2-E1 but not in a wild-type strain. Yeast two-hybrid and coimmunoprecipitation analyses verified interactions between Rng3p and the myosin head domain as well as interactions between Rng3p and Swo1p. Our analyses of Myo2p, Swo1p, and the UCS domain protein Rng3p establish that Swo1p and Rng3p collaborate in vivo to modulate myosin II function.

Magnesium Chloride is an Effective Therapeutic Agent for Prostate Cancer

2018 ◽  
Vol 8 (1) ◽  
pp. 62 ◽  
Author(s):  
Julianna Maria Santos ◽  
Fazle Hussain
Keyword(s):  
Prostate Cancer ◽  
Magnesium Chloride ◽  
Epithelial Mesenchymal Transition ◽  
Chromatin Condensation ◽  
Myosin Ii ◽  
In Vivo Studies ◽  
Migration Speed ◽  
Mesenchymal Transition

Background: Reduced levels of magnesium can cause several diseases and increase cancer risk. Motivated by magnesium chloride’s (MgCl2) non-toxicity, physiological importance, and beneficial clinical applications, we studied its action mechanism and possible mechanical, molecular, and physiological effects in prostate cancer with different metastatic potentials.Methods: We examined the effects of MgCl2, after 24 and 48 hours, on apoptosis, cell migration, expression of epithelial mesenchymal transition (EMT) markers, and V-H+-ATPase, myosin II (NMII) and the transcription factor NF Kappa B (NFkB) expressions.Results: MgCl2 induces apoptosis, and significantly decreases migration speed in cancer cells with different metastatic potentials.  MgCl2 reduces the expression of V-H+-ATPase and myosin II that facilitates invasion and metastasis, suppresses the expression of vimentin and increases expression of E-cadherin, suggesting a role of MgCl2 in reversing the EMT. MgCl2 also significantly increases the chromatin condensation and decreases NFkB expression.Conclusions: These results suggest a promising preventive and therapeutic role of MgCl2 for prostate cancer. Further studies should explore extending MgCl2 therapy to in vivo studies and other cancer types.Keywords: Magnesium chloride, prostate cancer, migration speed, V-H+-ATPase, and EMT.

The Mechanisms Behind the Biological Activity of Flavonoids

2019 ◽  
Vol 26 (39) ◽  
pp. 6976-6990 ◽  
Author(s):  
Ana María González-Paramás ◽  
Begoña Ayuda-Durán ◽  
Sofía Martínez ◽  
Susana González-Manzano ◽  
Celestino Santos-Buelga
Keyword(s):  
Gene Expression ◽  
Biological Activity ◽  
Phenolic Compounds ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Radical Scavenging ◽  
Model Organism ◽  
Stress Theory ◽  
Radical Scavenging Properties

: Flavonoids are phenolic compounds widely distributed in the human diet. Their intake has been associated with a decreased risk of different diseases such as cancer, immune dysfunction or coronary heart disease. However, the knowledge about the mechanisms behind their in vivo activity is limited and still under discussion. For years, their bioactivity was associated with the direct antioxidant and radical scavenging properties of phenolic compounds, but nowadays this assumption is unlikely to explain their putative health effects, or at least to be the only explanation for them. New hypotheses about possible mechanisms have been postulated, including the influence of the interaction of polyphenols and gut microbiota and also the possibility that flavonoids or their metabolites could modify gene expression or act as potential modulators of intracellular signaling cascades. This paper reviews all these topics, from the classical view as antioxidants in the context of the Oxidative Stress theory to the most recent tendencies related with the modulation of redox signaling pathways, modification of gene expression or interactions with the intestinal microbiota. The use of C. elegans as a model organism for the study of the molecular mechanisms involved in biological activity of flavonoids is also discussed.

scholarly journals The roles and prognostic significance of ABI1-TSV-11 expression in patients with left-sided colorectal cancer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu Zhang ◽  
Zhaohui Zhong ◽  
Mei Li ◽  
Jingyi Chen ◽  
Tingru Lin ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Prognostic Significance ◽  
Growth Factor Receptor ◽  
The Cancer Genome Atlas ◽  
Actin Dynamics ◽  
Elevated Expression ◽  
Sw480 Cells ◽  
And Migration

AbstractAbnormally expressed and/or phosphorylated Abelson interactor 1 (ABI1) participates in the metastasis and progression of colorectal cancer (CRC). ABI1 presents as at least 12 transcript variants (TSVs) by mRNA alternative splicing, but it is unknown which of them is involved in CRC metastasis and prognosis. Here, we firstly identified ABI1-TSV-11 as a key TSV affecting the metastasis and prognosis of left-sided colorectal cancer (LsCC) and its elevated expression is related to lymph node metastasis and shorter overall survival (OS) in LsCC by analyzing data from The Cancer Genome Atlas and TSVdb. Secondly, ABI1-TSV-11 overexpression promoted LoVo and SW480 cells adhesion and migration in vitro, and accelerated LoVo and SW480 cells lung metastasis in vivo. Finally, mechanism investigations revealed that ABI1-isoform-11 interacted with epidermal growth factor receptor pathway substrate 8 (ESP8) and regulated actin dynamics to affect LoVo and SW480 cells biological behaviors. Taken together, our data demonstrated that ABI1-TSV-11 plays an oncogenic role in LsCC, it is an independent risk factor of prognosis and may be a potential molecular marker and therapeutic target in LsCC.

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