Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.084
Filtrar
1.
Nat Commun ; 12(1): 5462, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34526503

RESUMO

Salicylic acid is a phenolic phytohormone which controls plant growth and development. A methyl ester (MSA) derivative thereof is volatile and involved in plant-insect or plant-plant communication. Here we show that the nematode-trapping fungus Duddingtonia flagrans uses a methyl-salicylic acid isomer, 6-MSA as morphogen for spatiotemporal control of trap formation and as chemoattractant to lure Caenorhabditis elegans into fungal colonies. 6-MSA is the product of a polyketide synthase and an intermediate in the biosynthesis of arthrosporols. The polyketide synthase (ArtA), produces 6-MSA in hyphal tips, and is uncoupled from other enzymes required for the conversion of 6-MSA to arthrosporols, which are produced in older hyphae. 6-MSA and arthrosporols both block trap formation. The presence of nematodes inhibits 6-MSA and arthrosporol biosyntheses and thereby enables trap formation. 6-MSA and arthrosporols are thus morphogens with some functions similar to quorum-sensing molecules. We show that 6-MSA is important in interkingdom communication between fungi and nematodes.


Assuntos
Ascomicetos/fisiologia , Caenorhabditis elegans/fisiologia , Hifas/fisiologia , Comportamento Predatório/fisiologia , Ácido Salicílico/metabolismo , Animais , Ascomicetos/genética , Ascomicetos/metabolismo , Quimiotaxia/fisiologia , Proteínas Fúngicas/metabolismo , Hifas/genética , Hifas/metabolismo , Policetídeo Sintases/metabolismo , Ácido Salicílico/química , Esporos Fúngicos/genética , Esporos Fúngicos/metabolismo
2.
Int J Mol Sci ; 22(16)2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34445739

RESUMO

Environmental changes trigger the continuous adaptation of bacteria to ensure their survival. This is possible through a variety of signal transduction pathways involving chemoreceptors known as methyl-accepting chemotaxis proteins (MCP) that allow the microorganisms to redirect their mobility towards favorable environments. MCP are two-component regulatory (or signal transduction) systems (TCS) formed by a sensor and a response regulator domain. These domains synchronize transient protein phosphorylation and dephosphorylation events to convert the stimuli into an appropriate cellular response. In this review, the variability of TCS domains and the most common signaling mechanisms are highlighted. This is followed by the description of the overall cellular topology, classification and mechanisms of MCP. Finally, the structural and functional properties of a new family of MCP found in Geobacter sulfurreducens are revisited. This bacterium has a diverse repertoire of chemosensory systems, which represents a striking example of a survival mechanism in challenging environments. Two G. sulfurreducens MCP-GSU0582 and GSU0935-are members of a new family of chemotaxis sensor proteins containing a periplasmic PAS-like sensor domain with a c-type heme. Interestingly, the cellular location of this domain opens new routes to the understanding of the redox potential sensing signaling transduction pathways.


Assuntos
Quimiotaxia/fisiologia , Geobacter/fisiologia , Proteínas Quimiotáticas Aceptoras de Metil/fisiologia , Transdução de Sinais
3.
Int J Mol Sci ; 22(13)2021 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-34203411

RESUMO

Non-genetic phenotypic diversity plays a significant role in the chemotactic behavior of bacteria, influencing how populations sense and respond to chemical stimuli. First, we review the molecular mechanisms that generate phenotypic diversity in bacterial chemotaxis. Next, we discuss the functional consequences of phenotypic diversity for the chemosensing and chemotactic performance of single cells and populations. Finally, we discuss mechanisms that modulate the amount of phenotypic diversity in chemosensory parameters in response to changes in the environment.


Assuntos
Fatores Quimiotáticos/metabolismo , Quimiotaxia/fisiologia , Animais , Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Fatores Quimiotáticos/genética , Quimiotaxia/genética , Humanos , Transdução de Sinais/genética , Transdução de Sinais/fisiologia
4.
Int J Mol Sci ; 22(14)2021 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-34299284

RESUMO

Forkhead box E1 (FOXE1) is a lineage-restricted transcription factor involved in thyroid cancer susceptibility. Cancer-associated polymorphisms map in regulatory regions, thus affecting the extent of gene expression. We have recently shown that genetic reduction of FOXE1 dosage modifies multiple thyroid cancer phenotypes. To identify relevant effectors playing roles in thyroid cancer development, here we analyse FOXE1-induced transcriptional alterations in thyroid cells that do not express endogenous FOXE1. Expression of FOXE1 elicits cell migration, while transcriptome analysis reveals that several immune cells-related categories are highly enriched in differentially expressed genes, including several upregulated chemokines involved in macrophage recruitment. Accordingly, FOXE1-expressing cells induce chemotaxis of co-cultured monocytes. We then asked if FOXE1 was able to regulate macrophage infiltration in thyroid cancers in vivo by using a mouse model of cancer, either wild type or with only one functional FOXE1 allele. Expression of the same set of chemokines directly correlates with FOXE1 dosage, and pro-tumourigenic M2 macrophage infiltration is decreased in tumours with reduced FOXE1. These data establish a novel link between FOXE1 and macrophages recruitment in the thyroid cancer microenvironment, highlighting an unsuspected function of this gene in the crosstalk between neoplastic and immune cells that shape tumour development and progression.


Assuntos
Quimiotaxia/fisiologia , Fatores de Transcrição Forkhead/genética , Macrófagos/patologia , Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/patologia , Animais , Células Cultivadas , Modelos Animais de Doenças , Fatores de Transcrição Forkhead/biossíntese , Fatores de Transcrição Forkhead/metabolismo , Humanos , Técnicas In Vitro , Macrófagos/citologia , Camundongos , Camundongos Knockout , Ratos , Ratos Endogâmicos F344 , Glândula Tireoide/metabolismo , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/metabolismo
5.
Commun Biol ; 4(1): 669, 2021 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-34083715

RESUMO

How motile bacteria navigate environmental chemical gradients has implications ranging from health to climate science, but the underlying behavioral mechanisms are unknown for most species. The well-studied navigation strategy of Escherichia coli forms a powerful paradigm that is widely assumed to translate to other bacterial species. This assumption is rarely tested because of a lack of techniques capable of bridging scales from individual navigation behavior to the resulting population-level chemotactic performance. Here, we present such a multiscale 3D chemotaxis assay by combining high-throughput 3D bacterial tracking with microfluidically created chemical gradients. Large datasets of 3D trajectories yield the statistical power required to assess chemotactic performance at the population level, while simultaneously resolving the underlying 3D navigation behavior for every individual. We demonstrate that surface effects confound typical 2D chemotaxis assays, and reveal that, contrary to previous reports, Caulobacter crescentus breaks with the E. coli paradigm.


Assuntos
Algoritmos , Quimiotaxia/fisiologia , Escherichia coli/fisiologia , Ensaios de Triagem em Larga Escala/métodos , Técnicas Analíticas Microfluídicas/métodos , Modelos Biológicos , Caulobacter crescentus/fisiologia , Especificidade da Espécie
6.
Biomolecules ; 11(4)2021 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-33806045

RESUMO

Chemotactic responses in motile bacteria are the result of sophisticated signal transduction by large, highly organized arrays of sensory proteins. Despite tremendous progress in the understanding of chemosensory array structure and function, a structural basis for the heightened sensitivity of networked chemoreceptors is not yet complete. Here, we present cryo-electron tomography visualisations of native-state chemosensory arrays in E. coli minicells. Strikingly, these arrays appear to exhibit a p2-symmetric array architecture that differs markedly from the p6-symmetric architecture previously described in E. coli. Based on this data, we propose molecular models of this alternative architecture and the canonical p6-symmetric assembly. We evaluate our observations and each model in the context of previously published data, assessing the functional implications of an alternative architecture and effects for future studies.


Assuntos
Proteínas de Escherichia coli/química , Escherichia coli/metabolismo , Histidina Quinase/química , Proteínas Quimiotáticas Aceptoras de Metil/química , Quimiotaxia/fisiologia , Microscopia Crioeletrônica , Dimerização , Modelos Moleculares
7.
Phys Rev Lett ; 126(12): 128102, 2021 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-33834835

RESUMO

The chemotactic network of Escherichia coli has been studied extensively both biophysically and information theoretically. Nevertheless, connection between these two aspects is still elusive. In this work, we report such a connection. We derive an optimal filtering dynamics under the assumption that E. coli's sensory system optimally infers the binary information whether it is swimming up or down along an exponential ligand gradient from noisy sensory signals. Then we show that a standard biochemical model of the chemotactic network is mathematically equivalent to this information-theoretically optimal dynamics. Moreover, we demonstrate that an experimentally observed nonlinear response relation can be reproduced from the optimal dynamics. These results suggest that the biochemical network of E. coli chemotaxis is designed to optimally extract the binary information along an exponential gradient in a noisy condition.


Assuntos
Quimiotaxia/fisiologia , Escherichia coli/fisiologia , Modelos Biológicos
8.
Nat Commun ; 12(1): 1990, 2021 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-33790272

RESUMO

A crucial phase in the infection process, which remains poorly understood, is the localization of suitable host cells by bacteria. It is often assumed that chemotaxis plays a key role during this phase. Here, we report a quantitative study on how Salmonella Typhimurium search for T84 human colonic epithelial cells. Combining time-lapse microscopy and mathematical modeling, we show that bacteria can be described as chiral active particles with strong active speed fluctuations, which are of biological, as opposed to thermal, origin. We observe that there exists a giant range of inter-individual variability of the bacterial exploring capacity. Furthermore, we find Salmonella Typhimurium does not exhibit biased motion towards the cells and show that the search time statistics is consistent with a random search strategy. Our results indicate that in vitro localization of host cells, and also cell infection, are random processes, not involving chemotaxis, that strongly depend on bacterial motility parameters.


Assuntos
Algoritmos , Aderência Bacteriana/fisiologia , Células Epiteliais/metabolismo , Salmonella typhimurium/metabolismo , Linhagem Celular Tumoral , Quimiotaxia/fisiologia , Células Epiteliais/microbiologia , Interações Hospedeiro-Patógeno , Humanos , Locomoção/fisiologia , Microscopia/métodos , Movimento (Física) , Salmonella typhimurium/fisiologia , Imagem com Lapso de Tempo/métodos
9.
PLoS Comput Biol ; 17(4): e1008826, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33844682

RESUMO

Sperm of marine invertebrates have to find eggs cells in the ocean. Turbulent flows mix sperm and egg cells up to the millimeter scale; below this, active swimming and chemotaxis become important. Previous work addressed either turbulent mixing or chemotaxis in still water. Here, we present a general theory of sperm chemotaxis inside the smallest eddies of turbulent flow, where signaling molecules released by egg cells are spread into thin concentration filaments. Sperm cells 'surf' along these filaments towards the egg. External flows make filaments longer, but also thinner. These opposing effects set an optimal flow strength. The optimum predicted by our theory matches flow measurements in shallow coastal waters. Our theory quantitatively agrees with two previous fertilization experiments in Taylor-Couette chambers and provides a mechanistic understanding of these early experiments. 'Surfing along concentration filaments' could be a paradigm for navigation in complex environments in the presence of turbulent flow.


Assuntos
Organismos Aquáticos/fisiologia , Quimiotaxia/fisiologia , Motilidade Espermática , Espermatozoides/fisiologia , Animais , Masculino
10.
Microbiol Mol Biol Rev ; 85(1)2021 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-33441490

RESUMO

Bacteria have evolved a variety of signal transduction mechanisms that generate different outputs in response to external stimuli. Chemosensory pathways are widespread in bacteria and are among the most complex signaling mechanisms, requiring the participation of at least six proteins. These pathways mediate flagellar chemotaxis, in addition to controlling alternative functions such as second messenger levels or twitching motility. The human pathogen Pseudomonas aeruginosa has four different chemosensory pathways that carry out different functions and are stimulated by signal binding to 26 chemoreceptors. Recent research employing a diverse range of experimental approaches has advanced enormously our knowledge on these four pathways, establishing P. aeruginosa as a primary model organism in this field. In the first part of this article, we review data on the function and physiological relevance of chemosensory pathways as well as their involvement in virulence, whereas the different transcriptional and posttranscriptional regulatory mechanisms that govern pathway function are summarized in the second part. The information presented will be of help to advance the understanding of pathway function in other organisms.


Assuntos
Quimiotaxia/fisiologia , Pseudomonas aeruginosa/metabolismo , Transdução de Sinais/fisiologia , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/genética , Histidina Quinase/metabolismo , Proteínas Quimiotáticas Aceptoras de Metil/metabolismo , Metilação , Metiltransferases/metabolismo
11.
Nat Commun ; 12(1): 348, 2021 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-33441540

RESUMO

In the enteric pathogen Salmonella enterica serovar Typhimurium, invasion and motility are coordinated by the master regulator HilD, which induces expression of the type III secretion system 1 (T3SS1) and motility genes. Methyl-accepting chemotaxis proteins (MCPs) detect specific ligands and control the direction of the flagellar motor, promoting tumbling and changes in direction (if a repellent is detected) or smooth swimming (in the presence of an attractant). Here, we show that HilD induces smooth swimming by upregulating an uncharacterized MCP (McpC), and this is important for invasion of epithelial cells. Remarkably, in vitro assays show that McpC can suppress tumbling and increase smooth swimming in the absence of exogenous ligands. Expression of mcpC is repressed by the universal regulator H-NS, which can be displaced by HilD. Our results highlight the importance of smooth swimming for Salmonella Typhimurium invasiveness and indicate that McpC can act via a ligand-independent mechanism when incorporated into the chemotactic receptor array.


Assuntos
Proteínas de Bactérias/metabolismo , Quimiotaxia/fisiologia , Proteínas Quimiotáticas Aceptoras de Metil/metabolismo , Salmonella typhimurium/metabolismo , Fatores de Transcrição/metabolismo , Animais , Proteínas de Bactérias/genética , Células CACO-2 , Bovinos , Células Cultivadas , Quimiotaxia/genética , Regulação Bacteriana da Expressão Gênica , Células HeLa , Humanos , Proteínas Quimiotáticas Aceptoras de Metil/genética , Camundongos Endogâmicos C57BL , Movimento/fisiologia , Mutação , Infecções por Salmonella/microbiologia , Salmonella typhimurium/genética , Salmonella typhimurium/fisiologia , Fatores de Transcrição/genética
12.
Theranostics ; 11(6): 2770-2787, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33456572

RESUMO

Aims: Extracellular vesicles (EVs) are membrane-derived vesicles that mediate intercellular communications. Neutrophils produce different subtypes of EVs during inflammatory responses. Neutrophil-derived trails (NDTRs) are generated by neutrophils migrating toward inflammatory foci, whereas neutrophil-derived microvesicles (NDMVs) are thought to be generated by neutrophils that have arrived at the inflammatory foci. However, the physical and functional characteristics of neutrophil-derived EVs are incompletely understood. In this study, we aimed to investigate the differences between NDTRs and NDMVs. Methods: The generation of neutrophil-derived EVs were visualized by live-cell fluorescence images and the physical characteristics were further analyzed using nanotracking analysis assay, scanning electron microscopic analysis, and marker expressions. Functional characteristics of neutrophil-derived EVs were analyzed using assays for bactericidal activity, monocyte chemotaxis, phenotype polarization of macrophages, and miRNA sequencing. Finally, the effects of neutrophil-derived EVs on the acute and chronic inflammation were examined in vivo. Results: Both EVs share similar characteristics including stimulators, surface marker expression, bactericidal activity, and chemoattractive effect on monocytes via MCP-1. However, the integrin-mediated physical interaction was required for generation of NDTRs whereas NDMV generation was dependent on PI3K pathway. Interestingly, NDTRs contained proinflammatory miRNAs such as miR-1260, miR-1285, miR-4454, and miR-7975, while NDMVs contained anti-inflammatory miRNAs such as miR-126, miR-150, and miR-451a. Although both EVs were easily uptaken by monocytes, NDTRs enhanced proinflammatory macrophage polarization whereas NDMVs induced anti-inflammatory macrophage polarization. Moreover, NDTRs showed protective effects against lethality in a murine sepsis model and pathological changes in a murine chronic colitis model. Conclusion: These results suggest that NDTR is a proinflammatory subtype of neutrophil-derived EVs distinguished from NDMV.


Assuntos
Vesículas Extracelulares/metabolismo , Inflamação/metabolismo , Neutrófilos/metabolismo , Animais , Biomarcadores/metabolismo , Comunicação Celular/fisiologia , Células Cultivadas , Quimiotaxia/fisiologia , Colite/metabolismo , Modelos Animais de Doenças , Humanos , Ativação de Macrófagos/fisiologia , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , MicroRNAs/metabolismo , Monócitos/metabolismo , Sepse/metabolismo , Células THP-1/metabolismo
13.
Sci Rep ; 11(1): 778, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436661

RESUMO

The human leukemia cell line (HL-60) is an alternative to primary neutrophils in research studies. However, because HL-60 cells proliferate in an incompletely differentiated state, they must undergo differentiation before they acquire the functional properties of neutrophils. Here we provide evidence of swarming and chemotaxis in differentiated HL-60 neutrophil-like cells (dHL-60) using precise microfluidic assays. We found that dimethyl sulfoxide differentiated HL-60 cells (DdHL-60) have a larger size, increased length, and lower ability to squeeze through narrow channels compared to primary neutrophils. They migrate through tapered microfluidic channels slower than primary neutrophils, but faster than HL-60s differentiated by other protocols, e.g., using all-trans retinoic acid. We found that dHL-60 can swarm toward zymosan particle clusters, though they display disorganized migratory patterns and produce swarms of smaller size compared to primary neutrophils.


Assuntos
Fatores Quimiotáticos/farmacologia , Quimiotaxia/fisiologia , Dimetil Sulfóxido/farmacologia , Neutrófilos/fisiologia , Tretinoína/farmacologia , Antineoplásicos/farmacologia , Diferenciação Celular/fisiologia , Crioprotetores/farmacologia , Células HL-60 , Humanos , Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/fisiologia , Neutrófilos/citologia , Neutrófilos/efeitos dos fármacos
14.
J Neuroinflammation ; 18(1): 21, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-33423699

RESUMO

Microglia react to danger signals by rapid and targeted extension of cellular processes towards the source of the signal. This positive chemotactic response is accompanied by a hyperpolarization of the microglia membrane. Here, we show that optogenetic depolarization of microglia has little effect on baseline motility, but significantly slows down the chemotactic response. Reducing the extracellular Ca2+ concentration mimics the effect of optogenetic depolarization. As the membrane potential sets the driving force for Ca2+ entry, hyperpolarization is an integral part of rapid stimulus-response coupling in microglia. Compared to typical excitable cells such as neurons, the sign of the activating response is inverted in microglia, leading to inhibition by depolarizing channelrhodopsins.


Assuntos
Sinalização do Cálcio/fisiologia , Quimiotaxia/fisiologia , Potenciais da Membrana/fisiologia , Microglia/fisiologia , Animais , Feminino , Hipocampo/química , Hipocampo/citologia , Hipocampo/fisiologia , Masculino , Camundongos , Camundongos Transgênicos , Microglia/química , Microscopia de Fluorescência por Excitação Multifotônica/métodos , Optogenética/métodos , Técnicas de Cultura de Órgãos
15.
Math Med Biol ; 38(1): 83-105, 2021 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-33338217

RESUMO

The aim of this article is to study the stability of a non-local kinetic model proposed by Loy & Preziosi (2020a) in which the cell speed is affected by the cell population density non-locally measured and weighted according to a sensing kernel in the direction of polarization and motion. We perform the analysis in a $d$-dimensional setting. We study the dispersion relation in the one-dimensional case and we show that the stability depends on two dimensionless parameters: the first one represents the stiffness of the system related to the cell turning rate, to the mean speed at equilibrium and to the sensing radius, while the second one relates to the derivative of the mean speed with respect to the density evaluated at the equilibrium. It is proved that for Dirac delta sensing kernels centered at a finite distance, corresponding to sensing limited to a given distance from the cell center, the homogeneous configuration is linearly unstable to short waves. On the other hand, for a uniform sensing kernel, corresponding to uniformly weighting the information collected up to a given distance, the most unstable wavelength is identified and consistently matches the numerical solution of the kinetic equation.


Assuntos
Movimento Celular/fisiologia , Modelos Biológicos , Animais , Contagem de Células/estatística & dados numéricos , Quimiotaxia/fisiologia , Simulação por Computador , Cinética , Modelos Lineares , Conceitos Matemáticos , Fenômenos Microbiológicos , Dinâmica não Linear , Probabilidade
16.
PLoS One ; 15(12): e0243442, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33296414

RESUMO

The trajectory of moving eukaryotic cells depends on the kinetics and direction of extending pseudopods. The direction of pseudopods has been well studied to unravel mechanisms for chemotaxis, wound healing and inflammation. However, the kinetics of pseudopod extension-when and why do pseudopods start and stop- is equally important, but is largely unknown. Here the START and STOP of about 4000 pseudopods was determined in four different species, at four conditions and in nine mutants (fast amoeboids Dictyostelium and neutrophils, slow mesenchymal stem cells, and fungus B.d. chytrid with pseudopod and a flagellum). The START of a first pseudopod is a random event with a probability that is species-specific (23%/s for neutrophils). In all species and conditions, the START of a second pseudopod is strongly inhibited by the extending first pseudopod, which depends on parallel filamentous actin/myosin in the cell cortex. Pseudopods extend at a constant rate by polymerization of branched F-actin at the pseudopod tip, which requires the Scar complex. The STOP of pseudopod extension is induced by multiple inhibitory processes that evolve during pseudopod extension and mainly depend on the increasing size of the pseudopod. Surprisingly, no differences in pseudopod kinetics are detectable between polarized, unpolarized or chemotactic cells, and also not between different species except for small differences in numerical values. This suggests that the analysis has uncovered the fundament of cell movement with distinct roles for stimulatory branched F-actin in the protrusion and inhibitory parallel F-actin in the contractile cortex.


Assuntos
Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Miosinas/metabolismo , Pseudópodes/fisiologia , Citoesqueleto de Actina/química , Citoesqueleto de Actina/fisiologia , Actinas/química , Animais , Movimento Celular/fisiologia , Quimiotaxia/fisiologia , Dictyostelium/química , Dictyostelium/fisiologia , Fungos/química , Fungos/fisiologia , Cinética , Células-Tronco Mesenquimais/química , Células-Tronco Mesenquimais/fisiologia , Miosinas/química , Neutrófilos/química , Neutrófilos/fisiologia , Pseudópodes/metabolismo
17.
Int J Mol Sci ; 21(22)2020 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-33187094

RESUMO

Many bacteria possess multiple chemosensory pathways that are composed of homologous signaling proteins. These pathways appear to be functionally insulated from each other, but little information is available on the corresponding molecular basis. We report here a novel mechanism that contributes to pathway insulation. We show that, of the four CheB paralogs of Pseudomonas aeruginosa PAO1, only CheB2 recognizes a pentapeptide at the C-terminal extension of the McpB (Aer2) chemoreceptor (KD = 93 µM). McpB is the sole chemoreceptor that stimulates the Che2 pathway, and CheB2 is the methylesterase of this pathway. Pectobacterium atrosepticum SCRI1043 has a single CheB, CheB_Pec, and 19 of its 36 chemoreceptors contain a C-terminal pentapeptide. The deletion of cheB_Pec abolished chemotaxis, but, surprisingly, none of the pentapeptides bound to CheB_Pec. To determine the corresponding structural basis, we solved the 3D structure of CheB_Pec. Its structure aligned well with that of the pentapeptide-dependent enzyme from Salmonella enterica. However, no electron density was observed in the CheB_Pec region corresponding to the pentapeptide-binding site in the Escherichia coli CheB. We hypothesize that this structural disorder is associated with the failure to bind pentapeptides. Combined data show that CheB methylesterases can be divided into pentapeptide-dependent and independent enzymes.


Assuntos
Proteínas de Bactérias/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Peptídeos/metabolismo , Sequência de Aminoácidos , Sítios de Ligação/fisiologia , Células Quimiorreceptoras/metabolismo , Quimiotaxia/fisiologia , Escherichia coli/metabolismo , Metiltransferases/metabolismo , Pectobacterium/metabolismo , Pseudomonas aeruginosa/metabolismo , Salmonella enterica/metabolismo , Transdução de Sinais/fisiologia
18.
Int J Mol Sci ; 21(22)2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33182643

RESUMO

Keratinocyte migration is initiated toward the wound skin barrier as a crucial process in wound healing. However, the migratory machinery used by keratinocytes is relatively unknown. Histamine signaling, including an increase in the Ca2+ signal, mediated the enhanced protein expression and chloride/bicarbonate exchange activity of anion exchanger AE2 in keratinocytes. In this study, we applied an agarose spot assay to induce a vectorial motion. The vectorial stimulation of the histamine-containing agarose spot enhanced the HaCaT keratinocyte migration, compared to non-directional stimulation. AE2 is associated with the vectorial movement of HaCaT keratinocytes. Enhanced expression of AE2 was mainly associated with an increase in Ca2+ and was abolished by the treatment with the Ca2+ chelating agent BAPTA-AM. These findings revealed that the directionality of Ca2+-exerted stimulation can play a prominent role in facilitating migration through the involvement of AE2 as a migratory machinery in HaCaT keratinocytes.


Assuntos
Sinalização do Cálcio , Queratinócitos/fisiologia , Cloreto de Cálcio/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Movimento Celular/fisiologia , Células Cultivadas , Quimiotaxia/efeitos dos fármacos , Quimiotaxia/fisiologia , Antiportadores de Cloreto-Bicarbonato/antagonistas & inibidores , Antiportadores de Cloreto-Bicarbonato/genética , Antiportadores de Cloreto-Bicarbonato/metabolismo , Dissulfiram/farmacologia , Histamina/farmacologia , Humanos , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Modelos Biológicos , Pele/lesões , Pele/patologia , Pele/fisiopatologia , Cicatrização/efeitos dos fármacos , Cicatrização/fisiologia
19.
Proc Natl Acad Sci U S A ; 117(41): 25553-25559, 2020 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-32999070

RESUMO

Neutrophils and dendritic cells when migrating in confined environments have been shown to actuate a directional choice toward paths of least hydraulic resistance (barotaxis), in some cases overriding chemotactic responses. Here, we investigate whether this barotactic response is conserved in the more primitive model organism Dictyostelium discoideum using a microfluidic chip design. This design allowed us to monitor the behavior of single cells via live imaging when confronted with bifurcating microchannels, presenting different combinations of hydraulic and chemical stimuli. Under the conditions employed we find no evidence in support of a barotactic response; the cells base their directional choices on the chemotactic cues. When the cells are confronted by a microchannel bifurcation, they often split their leading edge and start moving into both channels, before a decision is made to move into one and retract from the other channel. Analysis of this decision-making process has shown that cells in steeper nonhydrolyzable adenosine- 3', 5'- cyclic monophosphorothioate, Sp- isomer (cAMPS) gradients move faster and split more readily. Furthermore, there exists a highly significant strong correlation between the velocity of the pseudopod moving up the cAMPS gradient to the total velocity of the pseudopods moving up and down the gradient over a large range of velocities. This suggests a role for a critical cortical tension gradient in the directional decision-making process.


Assuntos
Movimento Celular/fisiologia , Tomada de Decisões/fisiologia , Dictyostelium/fisiologia , Modelos Biológicos , Resposta Táctica/fisiologia , Quimiotaxia/fisiologia , Desenho de Equipamento , Técnicas Analíticas Microfluídicas , Pressão , Análise de Célula Única
20.
Elife ; 92020 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-33064078

RESUMO

At the origin of multicellularity, cells may have evolved aggregation in response to predation, for functional specialisation or to allow large-scale integration of environmental cues. These group-level properties emerged from the interactions between cells in a group, and determined the selection pressures experienced by these cells. We investigate the evolution of multicellularity with an evolutionary model where cells search for resources by chemotaxis in a shallow, noisy gradient. Cells can evolve their adhesion to others in a periodically changing environment, where a cell's fitness solely depends on its distance from the gradient source. We show that multicellular aggregates evolve because they perform chemotaxis more efficiently than single cells. Only when the environment changes too frequently, a unicellular state evolves which relies on cell dispersal. Both strategies prevent the invasion of the other through interference competition, creating evolutionary bi-stability. Therefore, collective behaviour can be an emergent selective driver for undifferentiated multicellularity.


Assuntos
Evolução Biológica , Comunicação Celular , Adesão Celular , Comunicação Celular/fisiologia , Quimiotaxia/fisiologia , Modelos Biológicos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...