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Current Biology : CB May 2023Eukaryotic cells can undergo chemorepulsion, but the molecular mechanisms behind this phenomenon have remained unclear. Using Dictyostelium cells, a new study shows that...
Eukaryotic cells can undergo chemorepulsion, but the molecular mechanisms behind this phenomenon have remained unclear. Using Dictyostelium cells, a new study shows that competition of two ligands for the same receptors results in chemorepulsion, thus revealing a simple rule for eukaryotic cells to achieve negative chemotaxis.
Topics: Chemotaxis; Dictyostelium; Eukaryotic Cells
PubMed: 37160099
DOI: 10.1016/j.cub.2023.03.076 -
ELife May 2021Filopodia are thin, actin-based structures that cells use to interact with their environments. Filopodia initiation requires a suite of conserved proteins but the...
Filopodia are thin, actin-based structures that cells use to interact with their environments. Filopodia initiation requires a suite of conserved proteins but the mechanism remains poorly understood. The actin polymerase VASP and a MyTH-FERM (MF) myosin, DdMyo7 in amoeba, are essential for filopodia initiation. DdMyo7 is localized to dynamic regions of the actin-rich cortex. Analysis of VASP mutants and treatment of cells with anti-actin drugs shows that myosin recruitment and activation in requires localized VASP-dependent actin polymerization. Targeting of DdMyo7 to the cortex alone is not sufficient for filopodia initiation; VASP activity is also required. The actin regulator locally produces a cortical actin network that activates myosin and together they shape the actin network to promote extension of parallel bundles of actin during filopodia formation. This work reveals how filopodia initiation requires close collaboration between an actin-binding protein, the state of the actin cytoskeleton and MF myosin activity.
Topics: Actins; Cell Adhesion Molecules; Dictyostelium; Microfilament Proteins; Movement; Myosins; Phosphoproteins; Protozoan Proteins; Pseudopodia; Time Factors
PubMed: 34042588
DOI: 10.7554/eLife.68082 -
Small GTPases Sep 2019Rap1 belongs to the Ras family of small GTPases, which are involved in a multitude of cellular signal transduction pathways and have extensively been linked to cancer... (Review)
Review
Rap1 belongs to the Ras family of small GTPases, which are involved in a multitude of cellular signal transduction pathways and have extensively been linked to cancer biogenesis and metastasis. The small GTPase is activated in response to various extracellular and intracellular cues. Rap1 has conserved functions in amoeba and mammalian cells, which are important for cell polarity, substrate and cell-cell adhesion and other processes that involve the regulation of cytoskeletal dynamics. Moreover, our recent study has shown that Rap1 is required for the formation of the replication-permissive vacuole of an intracellular bacterial pathogen. Here we review the function and regulation of Rap1 in these distinct processes, and we discuss the underlying signal transduction pathways.
Topics: Animals; Bacterial Infections; Cytoskeleton; Dictyostelium; Humans; Neoplasm Metastasis; Neoplasm Proteins; Neoplasms; Protozoan Proteins; Shelterin Complex; Signal Transduction; Telomere-Binding Proteins
PubMed: 28632994
DOI: 10.1080/21541248.2017.1331721 -
Microbiology (Reading, England) Aug 2020Biofilm-associated infections are difficult to eradicate because of their ability to tolerate antibiotics and evade host immune responses. Amoebae and/or their secreted...
Biofilm-associated infections are difficult to eradicate because of their ability to tolerate antibiotics and evade host immune responses. Amoebae and/or their secreted products may provide alternative strategies to inhibit and disperse biofilms on biotic and abiotic surfaces. We evaluated the potential of five predatory amoebae - , , , and - and their cell-free secretions to disrupt biofilms formed by methicillin-resistant (MRSA) and . The biofilm biomass produced by MRSA and was significantly reduced when co-incubated with , and , and their corresponding cell-free supernatants (CFS). spp. generally produced CFS that mediated biofilm dispersal rather than directly killing the bacteria; however, CFS demonstrated active killing of MRSA planktonic cells when the bacteria were present at low concentrations. The active component(s) of the CFS is resistant to freezing, but can be inactivated to differing degrees by mechanical disruption and exposure to heat. and its CFS also reduced preformed biofilms, whereas only decreased biofilm biomass when amoebae were added. These results highlight the potential of using select amoebae species or their CFS to disrupt preformed bacterial biofilms.
Topics: Amoebida; Antibiosis; Biofilms; Cell Survival; Culture Media, Conditioned; Methicillin-Resistant Staphylococcus aureus; Mycobacterium bovis; Species Specificity
PubMed: 32459167
DOI: 10.1099/mic.0.000933 -
Cells Nov 2021The social amoeba provides an excellent model for research across a broad range of disciplines within biology. The organism diverged from the plant, yeast, fungi and... (Review)
Review
The social amoeba provides an excellent model for research across a broad range of disciplines within biology. The organism diverged from the plant, yeast, fungi and animal kingdoms around 1 billion years ago but retains common aspects found in these kingdoms. has a low level of genetic complexity and provides a range of molecular, cellular, biochemical and developmental biology experimental techniques, enabling multidisciplinary studies to be carried out in a wide range of areas, leading to research breakthroughs. Numerous laboratories within the United Kingdom employ as their core research model. This review introduces and then highlights research from several leading British research laboratories, covering their distinct areas of research, the benefits of using the model, and the breakthroughs that have arisen due to the use of as a tractable model system.
Topics: Animals; Biology; Dictyostelium; Drug Discovery; Models, Biological; Protein Processing, Post-Translational; Research; United Kingdom
PubMed: 34831258
DOI: 10.3390/cells10113036 -
Glycobiology Apr 2023O-GlcNAcylation is a prominent modification of nuclear and cytoplasmic proteins in animals and plants and is mediated by a single O-GlcNAc transferase (OGT). Spindly...
O-GlcNAcylation is a prominent modification of nuclear and cytoplasmic proteins in animals and plants and is mediated by a single O-GlcNAc transferase (OGT). Spindly (Spy), a paralog of OGT first discovered in higher plants, has an ortholog in the apicomplexan parasite Toxoplasma gondii, and both enzymes are now recognized as O-fucosyltransferases (OFTs). Here we investigate the evolution of spy-like genes and experimentally confirm OFT activity in the social amoeba Dictyostelium-a protist that is more related to fungi and metazoa. Immunofluorescence probing with the fucose-specific Aleuria aurantia lectin (AAL) and biochemical cell fractionation combined with western blotting suggested the occurrence of nucleocytoplasmic fucosylation. The absence of reactivity in mutants deleted in spy or gmd (unable to synthesize GDP-Fuc) suggested monofucosylation mediated by Spy. Genetic ablation of the modE locus, previously predicted to encode a GDP-fucose transporter, confirmed its necessity for fucosylation in the secretory pathway but not for the nucleocytoplasmic proteins. Affinity capture of these proteins combined with mass spectrometry confirmed monofucosylation of Ser and Thr residues of several known nucleocytoplasmic proteins. As in Toxoplasma, the Spy OFT was required for optimal proliferation of Dictyostelium under laboratory conditions. These findings support a new phylogenetic analysis of OGT and OFT evolution that indicates their occurrence in the last eukaryotic common ancestor but mostly complementary presence in its eukaryotic descendants with the notable exception that both occur in red algae and plants. Their generally exclusive expression, high degree of conservation, and shared monoglycosylation targets suggest overlapping roles in physiological regulation.
Topics: Animals; Fucosyltransferases; Dictyostelium; Fucose; Phylogeny; Bacteria; N-Acetylglucosaminyltransferases
PubMed: 36250576
DOI: 10.1093/glycob/cwac071 -
Frontiers in Physiology 2022
PubMed: 36237534
DOI: 10.3389/fphys.2022.1038793 -
Frontiers in Physiology 2024I am often asked by students and younger colleagues and now by the editors of this issue to tell the history of the development of the motility assay and the dual-beam... (Review)
Review
I am often asked by students and younger colleagues and now by the editors of this issue to tell the history of the development of the motility assay and the dual-beam single-molecule laser trap assay for myosin-driven actin filament movement, used widely as key assays for understanding how both muscle and nonmuscle myosin molecular motors work. As for all discoveries, the history of the development of the myosin assays involves many people who are not authors of the final publications, but without whom the assays would not have been developed as they are. Also, early experiences shape how one develops ideas and experiments, and influence future discoveries in major ways. I am pleased here to trace my own path and acknowledge the many individuals involved and my early science experiences that led to the work I and my students, postdoctoral fellows, and sabbatical visitors did to develop these assays. Mentors are too often overlooked in historical descriptions of discoveries, and my story starts with those who mentored me.
PubMed: 38827995
DOI: 10.3389/fphys.2024.1390186 -
Physical Review. E Apr 2021Nonlinear oscillator systems are ubiquitous in biology and physics, and their control is a practical problem in many experimental systems. Here we study this problem in...
Nonlinear oscillator systems are ubiquitous in biology and physics, and their control is a practical problem in many experimental systems. Here we study this problem in the context of the two models of spatially coupled oscillators: the complex Ginzburg-Landau equation (CGLE) and a generalization of the CGLE in which oscillators are coupled through an external medium (emCGLE). We focus on external control drives that vary in both space and time. We find that the spatial distribution of the drive signal controls the frequency ranges over which oscillators synchronize to the drive and that boundary conditions strongly influence synchronization to external drives for the CGLE. Our calculations also show that the emCGLE has a low density regime in which a broad range of frequencies can be synchronized for low drive amplitudes. We study the bifurcation structure of these models and find that they are very similar to results for the driven Kuramoto model, a system with no spatial structure. We conclude by discussing qualitative implications of our results for controlling coupled oscillator systems such as the social amoebae Dictyostelium and populations of Belousov Zhabotinsky (BZ) catalytic particles using spatially structured external drives.
PubMed: 34005969
DOI: 10.1103/PhysRevE.103.042211 -
Frontiers in Genetics 2022Small GTPases are the key to actin cytoskeleton signaling, which opens the lock of effector proteins to forward the signal downstream in several cellular pathways. Actin... (Review)
Review
Small GTPases are the key to actin cytoskeleton signaling, which opens the lock of effector proteins to forward the signal downstream in several cellular pathways. Actin cytoskeleton assembly is associated with cell polarity, adhesion, movement and other functions in eukaryotic cells. Rho proteins, specifically Cdc42 and Rac, are the primary regulators of actin cytoskeleton dynamics in higher and lower eukaryotes. Effector proteins, present in an inactive state gets activated after binding to the GTP bound Cdc42/Rac to relay a signal downstream. Cdc42/Rac interactive binding (CRIB) motif is an essential conserved sequence found in effector proteins to interact with Cdc42 or Rac. A diverse range of Cdc42/Rac and their effector proteins have evolved from lower to higher eukaryotes. The present study has identified and further classified CRIB containing effector proteins in lower eukaryotes, focusing on parasitic protozoans causing neglected tropical diseases and taking human proteins as a reference point to the highest evolved organism in the evolutionary trait. Lower eukaryotes' CRIB containing proteins fall into conventional effector molecules, PAKs (p21 activated kinase), Wiskoit-Aldrich Syndrome proteins family, and some have unique domain combinations unlike any known proteins. We also highlight the correlation between the effector protein isoforms and their selective specificity for Cdc42 or Rac proteins during evolution. Here, we report CRIB containing effector proteins; ten in and , fourteen in , one in and . CRIB containing effector proteins that have been studied so far in humans are potential candidates for drug targets in cancer, neurological disorders, and others. Conventional CRIB containing proteins from protozoan parasites remain largely elusive and our data provides their identification and classification for further in-depth functional validations. The tropical diseases caused by protozoan parasites lack combinatorial drug targets as effective paradigms. Targeting signaling mechanisms operative in these pathogens can provide greater molecules in combatting their infections.
PubMed: 35186026
DOI: 10.3389/fgene.2022.781885