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1.
J Neuroinflammation ; 21(1): 167, 2024 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-38956605

RESUMEN

BACKGROUND: Deposition of amyloid ß, which is produced by amyloidogenic cleavage of APP by ß- and γ-secretase, is one of the primary hallmarks of AD pathology. APP can also be processed by α- and γ-secretase sequentially, to generate sAPPα, which has been shown to be neuroprotective by promoting neurite outgrowth and neuronal survival, etc. METHODS: The global expression profiles of miRNA in blood plasma samples taken from 11 AD patients as well as from 14 age and sex matched cognitively normal volunteers were analyzed using miRNA-seq. Then, overexpressed miR-140 and miR-122 both in vivo and in vitro, and knock-down of the endogenous expression of miR-140 and miR-122 in vitro. Used a combination of techniques, including molecular biology, immunohistochemistry, to detect the impact of miRNAs on AD pathology. RESULTS: In this study, we identified that two miRNAs, miR-140-3p and miR-122-5p, both targeting ADAM10, the main α-secretase in CNS, were upregulated in the blood plasma of AD patients. Overexpression of these two miRNAs in mouse brains induced cognitive decline in wild type C57BL/6J mice as well as exacerbated dyscognition in APP/PS1 mice. Although significant changes in APP and total Aß were not detected, significantly downregulated ADAM10 and its non-amyloidogenic product, sAPPα, were observed in the mouse brains overexpressing miR-140/miR-122. Immunohistology analysis revealed increased neurite dystrophy that correlated with the reduced microglial chemotaxis in the hippocampi of these mice, independent of the other two ADAM10 substrates (neuronal CX3CL1 and microglial TREM2) that were involved in regulating the microglial immunoactivity. Further in vitro analysis demonstrated that both the reduced neuritic outgrowth of mouse embryonic neuronal cells overexpressing miR-140/miR-122 and the reduced Aß phagocytosis in microglia cells co-cultured with HT22 cells overexpressing miR-140/miR-122 could be rescued by overexpressing the specific inhibitory sequence of miR-140/miR-122 TuD as well as by addition of sAPPα, rendering these miRNAs as potential therapeutic targets. CONCLUSIONS: Our results suggested that neuroprotective sAPPα was a key player in the neuropathological progression induced by dysregulated expression of miR-140 and miR-122. Targeting these miRNAs might serve as a promising therapeutic strategy in AD treatment.


Asunto(s)
Enfermedad de Alzheimer , Quimiotaxis , Ratones Endogámicos C57BL , MicroARNs , Microglía , MicroARNs/metabolismo , MicroARNs/genética , Animales , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Enfermedad de Alzheimer/genética , Ratones , Humanos , Microglía/metabolismo , Microglía/patología , Masculino , Quimiotaxis/fisiología , Femenino , Proteína ADAM10/metabolismo , Proteína ADAM10/genética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Secretasas de la Proteína Precursora del Amiloide/genética , Ratones Transgénicos , Anciano , Regulación de la Expresión Génica
2.
Elife ; 132024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38949655

RESUMEN

Secreted chemokines form concentration gradients in target tissues to control migratory directions and patterns of immune cells in response to inflammatory stimulation; however, how the gradients are formed is much debated. Heparan sulfate (HS) binds to chemokines and modulates their activities. In this study, we investigated the roles of HS in the gradient formation and chemoattractant activity of CCL5 that is known to bind to HS. CCL5 and heparin underwent liquid-liquid phase separation and formed gradient, which was confirmed using CCL5 immobilized on heparin-beads. The biological implication of HS in CCL5 gradient formation was established in CHO-K1 (wild-type) and CHO-677 (lacking HS) cells by Transwell assay. The effect of HS on CCL5 chemoattractant activity was further proved by Transwell assay of human peripheral blood cells. Finally, peritoneal injection of the chemokines into mice showed reduced recruitment of inflammatory cells either by mutant CCL5 (lacking heparin-binding sequence) or by addition of heparin to wild-type CCL5. Our experimental data propose that co-phase separation of CCL5 with HS establishes a specific chemokine concentration gradient to trigger directional cell migration. The results warrant further investigation on other heparin-binding chemokines and allows for a more elaborate insight into disease process and new treatment strategies.


Asunto(s)
Quimiocina CCL5 , Quimiotaxis , Cricetulus , Heparitina Sulfato , Quimiocina CCL5/metabolismo , Quimiocina CCL5/genética , Animales , Heparitina Sulfato/metabolismo , Humanos , Células CHO , Ratones , Heparina/metabolismo , Heparina/farmacología , Separación de Fases
3.
Nat Cell Biol ; 26(7): 1062-1076, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38951708

RESUMEN

Ras has been extensively studied as a promoter of cell proliferation, whereas few studies have explored its role in migration. To investigate the direct and immediate effects of Ras activity on cell motility or polarity, we focused on RasGAPs, C2GAPB in Dictyostelium amoebae and RASAL3 in HL-60 neutrophils and macrophages. In both cellular systems, optically recruiting the respective RasGAP to the cell front extinguished pre-existing protrusions and changed migration direction. However, when these respective RasGAPs were recruited uniformly to the membrane, cells polarized and moved more rapidly, whereas targeting to the back exaggerated these effects. These unexpected outcomes of attenuating Ras activity naturally had strong, context-dependent consequences for chemotaxis. The RasGAP-mediated polarization depended critically on myosin II activity and commenced with contraction at the cell rear, followed by sustained mTORC2-dependent actin polymerization at the front. These experimental results were captured by computational simulations in which Ras levels control front- and back-promoting feedback loops. The discovery that inhibiting Ras activity can produce counterintuitive effects on cell migration has important implications for future drug-design strategies targeting oncogenic Ras.


Asunto(s)
Actomiosina , Movimiento Celular , Polaridad Celular , Dictyostelium , Proteínas ras , Dictyostelium/metabolismo , Dictyostelium/genética , Células HL-60 , Actomiosina/metabolismo , Humanos , Proteínas ras/metabolismo , Proteínas ras/genética , Macrófagos/metabolismo , Miosina Tipo II/metabolismo , Miosina Tipo II/genética , Neutrófilos/metabolismo , Proteínas Activadoras de ras GTPasa/metabolismo , Proteínas Activadoras de ras GTPasa/genética , Animales , Quimiotaxis , Proteínas Protozoarias/metabolismo , Proteínas Protozoarias/genética , Actinas/metabolismo , Simulación por Computador , Ratones , Transducción de Señal
4.
Physiol Rep ; 12(14): e16139, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-39016176

RESUMEN

The monocyte-macrophage system plays an important role in phagocytosis of pathogens and cellular debris following infection or tissue injury in several pathophysiological conditions. We examined ENaC/ASIC subunit transcript expression and the importance of select subunits in migration of bone marrow derived monocytes (freshly isolated) and macrophages (monocytes differentiated in culture). We also examined the effect of select subunit deletion on macrophage phenotype. BM monocytes were harvested from the femurs of male and female WT and KO mice (6-12 weeks of age). Our results show that α, ß, γENaC, and ASIC1-5 transcripts are expressed in BM macrophages and monocytes to varying degrees. At least αENaC, ßENaC, and ASIC2 subunits contribute to chemotactic migration responses in BM monocyte-macrophages. Polarization markers (CD86, soluble TNFα) in BM macrophages from mice lacking ASIC2a plus ßENaC were shifted towards the M1 phenotype. Furthermore, select M1 phenotypic markers were recovered with rescue of ßENaC or ASIC2. Taken together, these data suggest that ßENaC and ASIC2 play an important role in BM macrophage migration and loss of ßENaC and/or ASIC2 partially polarizes macrophages to the M1 phenotype. Thus, targeting ENaC/ASIC expression in BM macrophages may regulate their ability to migrate to sites of injury.


Asunto(s)
Canales Iónicos Sensibles al Ácido , Quimiotaxis , Canales Epiteliales de Sodio , Macrófagos , Monocitos , Animales , Canales Epiteliales de Sodio/metabolismo , Canales Epiteliales de Sodio/genética , Macrófagos/metabolismo , Masculino , Ratones , Canales Iónicos Sensibles al Ácido/metabolismo , Canales Iónicos Sensibles al Ácido/genética , Femenino , Monocitos/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Células de la Médula Ósea/metabolismo , Células Cultivadas
5.
Cell Syst ; 15(7): 628-638.e8, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-38981486

RESUMEN

In uncertain environments, phenotypic diversity can be advantageous for survival. However, as the environmental uncertainty decreases, the relative advantage of having diverse phenotypes decreases. Here, we show how populations of E. coli integrate multiple chemical signals to adjust sensory diversity in response to changes in the prevalence of each ligand in the environment. Measuring kinase activity in single cells, we quantified the sensitivity distribution to various chemoattractants in different mixtures of background stimuli. We found that when ligands bind uncompetitively, the population tunes sensory diversity to each signal independently, decreasing diversity when the signal's ambient concentration increases. However, among competitive ligands, the population can only decrease sensory diversity one ligand at a time. Mathematical modeling suggests that sensory diversity tuning benefits E. coli populations by modulating how many cells are committed to tracking each signal proportionally as their prevalence changes.


Asunto(s)
Quimiotaxis , Escherichia coli , Transducción de Señal , Escherichia coli/metabolismo , Escherichia coli/fisiología , Quimiotaxis/fisiología , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Factores Quimiotácticos/metabolismo
6.
PLoS Biol ; 22(6): e3002672, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38935621

RESUMEN

Throughout history, humans have relied on plants as a source of medication, flavoring, and food. Plants synthesize large chemical libraries and release many of these compounds into the rhizosphere and atmosphere where they affect animal and microbe behavior. To survive, nematodes must have evolved the sensory capacity to distinguish plant-made small molecules (SMs) that are harmful and must be avoided from those that are beneficial and should be sought. This ability to classify chemical cues as a function of their value is fundamental to olfaction and represents a capacity shared by many animals, including humans. Here, we present an efficient platform based on multiwell plates, liquid handling instrumentation, inexpensive optical scanners, and bespoke software that can efficiently determine the valence (attraction or repulsion) of single SMs in the model nematode, Caenorhabditis elegans. Using this integrated hardware-wetware-software platform, we screened 90 plant SMs and identified 37 that attracted or repelled wild-type animals but had no effect on mutants defective in chemosensory transduction. Genetic dissection indicates that for at least 10 of these SMs, response valence emerges from the integration of opposing signals, arguing that olfactory valence is often determined by integrating chemosensory signals over multiple lines of information. This study establishes that C. elegans is an effective discovery engine for determining chemotaxis valence and for identifying natural products detected by the chemosensory nervous system.


Asunto(s)
Caenorhabditis elegans , Quimiotaxis , Ensayos Analíticos de Alto Rendimiento , Caenorhabditis elegans/fisiología , Caenorhabditis elegans/efectos de los fármacos , Animales , Ensayos Analíticos de Alto Rendimiento/métodos , Olfato/fisiología , Conducta Animal/efectos de los fármacos , Conducta Animal/fisiología , Programas Informáticos
7.
Int J Mol Sci ; 25(12)2024 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-38928010

RESUMEN

The identification of novel drug targets in plant-parasitic nematodes (PPNs) is imperative due to the loss of traditional nematicides and a lack of replacements. Chemosensation, which is pivotal for PPNs in locating host roots, has become a focus in nematode behavioral research. However, its underlying molecular basis is still indistinct in such a diverse group of PPNs. To characterize genes participating in chemosensation in the Javanese root-knot nematode Meloidogyne javanica, RNA-sequencing of the second-stage juveniles (J2s) treated with tomato root exudate (TRE) for 1 h and 6 h was performed. Genes related to chemosensation in M. javanica mainly responded to TRE treatment at 1 h. Moreover, a gene ontology (GO) analysis underscored the significance of the neuropeptide G protein-coupled receptor signaling pathway. Consequently, the repertoire of putative neuropeptides in M. javanica, including FMRFamide-like peptides (FLPs), insulin-like peptides (ILPs), and neuropeptide-like peptides (NLPs), were outlined based on a homology analysis. The gene Mjflp-14a, harboring two neuropeptides, was significantly up-regulated at 1 h TRE treatment. Through peptide synthesis and J2 treatment, one of the two neuropeptides (MjFLP-14-2) was proven to influence the J2 chemotaxis towards tomato root tips. Overall, our study reinforces the potential of nematode neuropeptides as novel targets and tools for root-knot nematode control.


Asunto(s)
Neuropéptidos , Raíces de Plantas , Solanum lycopersicum , Tylenchoidea , Animales , Tylenchoidea/fisiología , Neuropéptidos/metabolismo , Neuropéptidos/genética , Raíces de Plantas/parasitología , Raíces de Plantas/metabolismo , Raíces de Plantas/genética , Solanum lycopersicum/parasitología , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Enfermedades de las Plantas/parasitología , Enfermedades de las Plantas/genética , Quimiotaxis , Proteínas del Helminto/metabolismo , Proteínas del Helminto/genética
8.
Cells ; 13(11)2024 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-38891050

RESUMEN

Acute inflammation is a rapid and dynamic process involving the recruitment and activation of multiple cell types in a coordinated and precise manner. Here, we investigate the origin and transcriptional reprogramming of monocytes using a model of acute inflammation, zymosan-induced peritonitis. Monocyte trafficking and adoptive transfer experiments confirmed that monocytes undergo rapid phenotypic change as they exit the blood and give rise to monocyte-derived macrophages that persist during the resolution of inflammation. Single-cell transcriptomics revealed significant heterogeneity within the surface marker-defined CD11b+Ly6G-Ly6Chi monocyte populations within the blood and at the site of inflammation. We show that two major transcriptional reprogramming events occur during the initial six hours of Ly6Chi monocyte mobilisation, one in the blood priming monocytes for migration and a second at the site of inflammation. Pathway analysis revealed an important role for oxidative phosphorylation (OxPhos) during both these reprogramming events. Experimentally, we demonstrate that OxPhos via the intact mitochondrial electron transport chain is essential for murine and human monocyte chemotaxis. Moreover, OxPhos is needed for monocyte-to-macrophage differentiation and macrophage M(IL-4) polarisation. These new findings from transcriptional profiling open up the possibility that shifting monocyte metabolic capacity towards OxPhos could facilitate enhanced macrophage M2-like polarisation to aid inflammation resolution and tissue repair.


Asunto(s)
Antígenos Ly , Diferenciación Celular , Inflamación , Macrófagos , Monocitos , Fosforilación Oxidativa , Monocitos/metabolismo , Animales , Macrófagos/metabolismo , Inflamación/patología , Inflamación/metabolismo , Humanos , Ratones , Antígenos Ly/metabolismo , Quimiotaxis , Ratones Endogámicos C57BL , Peritonitis/metabolismo , Peritonitis/inducido químicamente , Peritonitis/patología , Zimosan/farmacología , Mitocondrias/metabolismo , Reprogramación Celular
9.
PLoS Comput Biol ; 20(6): e1012112, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38861575

RESUMEN

Cell sedimentation in 3D hydrogel cultures refers to the vertical migration of cells towards the bottom of the space. Understanding this poorly examined phenomenon may allow us to design better protocols to prevent it, as well as provide insights into the mechanobiology of cancer development. We conducted a multiscale experimental and mathematical examination of 3D cancer growth in triple negative breast cancer cells. Migration was examined in the presence and absence of Paclitaxel, in high and low adhesion environments and in the presence of fibroblasts. The observed behaviour was modeled by hypothesizing active migration due to self-generated chemotactic gradients. Our results did not reject this hypothesis, whereby migration was likely to be regulated by the MAPK and TGF-ß pathways. The mathematical model enabled us to describe the experimental data in absence (normalized error<40%) and presence of Paclitaxel (normalized error<10%), suggesting inhibition of random motion and advection in the latter case. Inhibition of sedimentation in low adhesion and co-culture experiments further supported the conclusion that cells actively migrated downwards due to the presence of signals produced by cells already attached to the adhesive glass surface.


Asunto(s)
Adhesión Celular , Movimiento Celular , Paclitaxel , Humanos , Adhesión Celular/fisiología , Movimiento Celular/fisiología , Paclitaxel/farmacología , Línea Celular Tumoral , Modelos Biológicos , Técnicas de Cultivo Tridimensional de Células/métodos , Neoplasias de la Mama Triple Negativas/patología , Biología Computacional , Fibroblastos/fisiología , Quimiotaxis/fisiología
11.
Sci Adv ; 10(24): eadk9731, 2024 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-38865458

RESUMEN

Nonlinear biomolecular interactions on membranes drive membrane remodeling crucial for biological processes including chemotaxis, cytokinesis, and endocytosis. The complexity of biomolecular interactions, their redundancy, and the importance of spatiotemporal context in membrane organization impede understanding of the physical principles governing membrane mechanics. Developing a minimal in vitro system that mimics molecular signaling and membrane remodeling while maintaining physiological fidelity poses a major challenge. Inspired by chemotaxis, we reconstructed chemically regulated actin polymerization inside vesicles, guiding membrane self-organization. An external, undirected chemical input induced directed actin polymerization and membrane deformation uncorrelated with upstream biochemical cues, suggesting symmetry breaking. A biophysical model incorporating actin dynamics and membrane mechanics proposes that uneven actin distributions cause nonlinear membrane deformations, consistent with experimental findings. This protocellular system illuminates the interplay between actin dynamics and membrane shape during symmetry breaking, offering insights into chemotaxis and other cell biological processes.


Asunto(s)
Actinas , Células Artificiales , Membrana Celular , Polimerizacion , Actinas/metabolismo , Células Artificiales/metabolismo , Células Artificiales/química , Membrana Celular/metabolismo , Quimiotaxis , Modelos Biológicos
12.
Elife ; 122024 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-38832501

RESUMEN

Bacteria in biofilms secrete potassium ions to attract free swimming cells. However, the basis of chemotaxis to potassium remains poorly understood. Here, using a microfluidic device, we found that Escherichia coli can rapidly accumulate in regions of high potassium concentration on the order of millimoles. Using a bead assay, we measured the dynamic response of individual flagellar motors to stepwise changes in potassium concentration, finding that the response resulted from the chemotaxis signaling pathway. To characterize the chemotactic response to potassium, we measured the dose-response curve and adaptation kinetics via an Förster resonance energy transfer (FRET) assay, finding that the chemotaxis pathway exhibited a sensitive response and fast adaptation to potassium. We further found that the two major chemoreceptors Tar and Tsr respond differently to potassium. Tar receptors exhibit a biphasic response, whereas Tsr receptors respond to potassium as an attractant. These different responses were consistent with the responses of the two receptors to intracellular pH changes. The sensitive response and fast adaptation allow bacteria to sense and localize small changes in potassium concentration. The differential responses of Tar and Tsr receptors to potassium suggest that cells at different growth stages respond differently to potassium and may have different requirements for potassium.


Asunto(s)
Quimiotaxis , Escherichia coli , Potasio , Potasio/metabolismo , Escherichia coli/fisiología , Proteínas de Escherichia coli/metabolismo , Transferencia Resonante de Energía de Fluorescencia , Transducción de Señal , Receptores de Superficie Celular
13.
PLoS One ; 19(6): e0305037, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38837976

RESUMEN

Bacteria use various motility mechanisms to explore their environments. Chemotaxis is the ability of a motile bacterial cell to direct its movement in response to chemical gradients. A number of methods have been developed and widely used to study chemotactic responses to chemoeffectors including capillary, agar plug, microscopic slide, and microfluidic assays. While valuable, these assays are primarily designed to monitor rapid chemotactic responses to chemoeffectors on a small scale, which poses challenges in collecting large quantities of attracted bacteria. Consequently, these setups are not ideal for experiments like forward genetic screens. To overcome this limitation, we developed the Large Scale Bacterial Attraction assay (LSBA), which relies on the use of a Nalgene™ Reusable Filter Unit and other materials commonly found in laboratories. We validate the LSBA by investigating chemoeffector kinetics in the setup and by using chemoattractants to quantify the chemotactic response of wild-type, and motility impaired strains of the plant pathogenic bacterium Xanthomonas campestris pv. campestris and the environmental bacterium Shewanella oneidensis. We show that the LSBA establishes a long lasting chemoeffector gradient, that the setup can be used to quantify bacterial migration over time and that the LSBA offers the possibility to collect high numbers of attracted bacteria, making it suitable for genetic screens.


Asunto(s)
Quimiotaxis , Shewanella , Quimiotaxis/genética , Shewanella/genética , Shewanella/fisiología , Xanthomonas campestris/genética , Pruebas Genéticas/métodos , Factores Quimiotácticos/farmacología , Bioensayo/métodos
14.
mBio ; 15(7): e0087124, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-38899869

RESUMEN

Chemosensory systems allow bacteria to respond and adapt to environmental conditions. Many bacteria contain more than one chemosensory system, but knowledge of their specific roles in regulating different functions remains scarce. Here, we address this issue by analyzing the function of the F6, F8, and alternative (non-motility) cellular functions (ACF) chemosensory systems of the model plant pathogen Pseudomonas syringae pv. tomato. In this work, we assign PsPto chemoreceptors to each chemosensory system, and we visualize for the first time the F6 and F8 chemosensory systems of PsPto using cryo-electron tomography. We confirm that chemotaxis and swimming motility are controlled by the F6 system, and we demonstrate how different components from the F8 and ACF systems also modulate swimming motility. We also determine how the kinase and response regulators from the F6 and F8 chemosensory systems do not work together in the regulation of biofilm, whereas both components from the ACF system contribute together to regulate these traits. Furthermore, we show how the F6, F8, and ACF kinases interact with the ACF response regulator WspR, supporting crosstalk among chemosensory systems. Finally, we reveal how all chemosensory systems play a role in regulating virulence. IMPORTANCE: Chemoperception through chemosensory systems is an essential feature for bacterial survival, as it allows bacterial interaction with its surrounding environment. In the case of plant pathogens, it is especially relevant to enter the host and achieve full virulence. Multiple chemosensory systems allow bacteria to display a wider plasticity in their response to external signals. Here, we perform a deep characterization of the F6, F8, and alternative (non-motility) cellular functions chemosensory systems in the model plant pathogen Pseudomonas syringae pv. tomato DC3000. These chemosensory systems regulate key virulence-related traits, like motility and biofilm formation. Furthermore, we unveil an unexpected crosstalk among these chemosensory systems at the level of the interaction between kinases and response regulators. This work shows novel results that contribute to the knowledge of chemosensory systems and their role in functions alternative to chemotaxis.


Asunto(s)
Proteínas Bacterianas , Biopelículas , Quimiotaxis , Pseudomonas syringae , Solanum lycopersicum , Pseudomonas syringae/genética , Pseudomonas syringae/patogenicidad , Pseudomonas syringae/metabolismo , Pseudomonas syringae/fisiología , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Biopelículas/crecimiento & desarrollo , Solanum lycopersicum/microbiología , Virulencia , Enfermedades de las Plantas/microbiología , Regulación Bacteriana de la Expresión Génica
15.
Appl Environ Microbiol ; 90(6): e0076024, 2024 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-38775579

RESUMEN

Motile plant-associated bacteria use chemotaxis and dedicated chemoreceptors to navigate gradients in their surroundings and to colonize host plant surfaces. Here, we characterize a chemoreceptor that we named Tlp2 in the soil alphaproteobacterium Azospirillum brasilense. We show that the Tlp2 ligand-binding domain is related to the 4-helix bundle family and is conserved in chemoreceptors found in the genomes of many soil- and sediment-dwelling alphaproteobacteria. The promoter of tlp2 is regulated in an NtrC- and RpoN-dependent manner and is most upregulated under conditions of nitrogen fixation or in the presence of nitrate. Using fluorescently tagged Tlp2 (Tlp2-YFP), we show that this chemoreceptor is present in low abundance in chemotaxis-signaling clusters and is prone to degradation. We also obtained evidence that the presence of ammonium rapidly disrupts Tlp2-YFP localization. Behavioral experiments using a strain lacking Tlp2 and variants of Tlp2 lacking conserved arginine residues suggest that Tlp2 mediates chemotaxis in gradients of nitrate and nitrite, with the R159 residue being essential for Tlp2 function. We also provide evidence that Tlp2 is essential for root surface colonization of some plants (teff, red clover, and cowpea) but not others (wheat, sorghum, alfalfa, and pea). These results highlight the selective role of nitrate sensing and chemotaxis in plant root surface colonization and illustrate the relative contribution of chemoreceptors to chemotaxis and root surface colonization.IMPORTANCEBacterial chemotaxis mediates host-microbe associations, including the association of beneficial bacteria with the roots of host plants. Dedicated chemoreceptors specify sensory preferences during chemotaxis. Here, we show that a chemoreceptor mediating chemotaxis to nitrate is important in the beneficial soil bacterium colonization of some but not all plant hosts tested. Nitrate is the preferred nitrogen source for plant nutrition, and plants sense and tightly control nitrate transport, resulting in varying nitrate uptake rates depending on the plant and its physiological state. Nitrate is thus a limiting nutrient in the rhizosphere. Chemotaxis and dedicated chemoreceptors for nitrate likely provide motile bacteria with a competitive advantage to access this nutrient in the rhizosphere.


Asunto(s)
Azospirillum brasilense , Proteínas Bacterianas , Quimiotaxis , Nitratos , Raíces de Plantas , Azospirillum brasilense/genética , Azospirillum brasilense/metabolismo , Azospirillum brasilense/fisiología , Nitratos/metabolismo , Raíces de Plantas/microbiología , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo
16.
J Med Entomol ; 61(4): 869-876, 2024 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-38781574

RESUMEN

Phlebotomine sand flies are important vectors of medical and veterinary importance, transmitting pathogens, such as the Leishmania parasites, responsible for 700,000 to 1 million new cases of leishmaniasis every year. The vast majority of the current sand fly surveillance and control tools are tailored against the adult stages, due to the limited knowledge on the ecology of the larval stages. Since vector control is primarily an ecological problem, an in-depth understanding of the behavior of the target insect pests across all the different life stages of their development is required prior to the development of effective control strategies. It is well known that chemical cues play an important role in insect behavior. While there are numerous studies investigating the behavior of adult sand flies in response to chemical sources, there is currently no information available on the response of their larval stages. In this study, novel bioassays were constructed to investigate the effect of chemical cues (gustatory and olfactory) on the behavior of Phlebotomus papatasi (Scopoli) sand fly larvae. The larvae exhibited a clear food preference within a few hours of exposure in a 2-choice bioassay, while, also, demonstrated positive chemotaxis in response to volatile stimuli emitted from their preferred food source. Identification of the specific chemical compounds (or the combination thereof) eliciting attractance response to sand fly immature stages could lead to the development of innovative, and targeted (larval-specific) tools for the surveillance, and management of these important public health pests.


Asunto(s)
Quimiotaxis , Larva , Phlebotomus , Animales , Phlebotomus/fisiología , Larva/crecimiento & desarrollo , Larva/fisiología , Prueba de Estudio Conceptual , Señales (Psicología) , Femenino
17.
Biophys J ; 123(12): 1654-1667, 2024 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-38815587

RESUMEN

To survive in ever-changing environments, living organisms need to continuously combine the ongoing external inputs they receive, representing present conditions, with their dynamical internal state, which includes influences of past experiences. It is still unclear in general, however 1) how this happens at the molecular and cellular levels and 2) how the corresponding molecular and cellular processes are integrated with the behavioral responses of the organism. Here, we address these issues by modeling mathematically a particular behavioral paradigm in a minimal model organism, namely chemotaxis in the nematode C. elegans. Specifically, we use a long-standing collection of elegant experiments on salt chemotaxis in this animal, in which the migration direction varies depending on its previous experience. Our model integrates the molecular, cellular, and organismal levels to reproduce the experimentally observed experience-dependent behavior. The model proposes specific molecular mechanisms for the encoding of current conditions and past experiences in key neurons associated with this response, predicting the behavior of various mutants associated with those molecular circuits.


Asunto(s)
Caenorhabditis elegans , Quimiotaxis , Caenorhabditis elegans/fisiología , Animales , Modelos Biológicos , Conducta Animal , Modelos Neurológicos
18.
Nat Commun ; 15(1): 3984, 2024 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-38734736

RESUMEN

Greenbeard genetic elements encode rare perceptible signals, signal recognition ability, and altruism towards others that display the same signal. Putative greenbeards have been described in various organisms but direct evidence for all the properties in one system is scarce. The tgrB1-tgrC1 allorecognition system of Dictyostelium discoideum encodes two polymorphic membrane proteins which protect cells from chimerism-associated perils. During development, TgrC1 functions as a ligand-signal and TgrB1 as its receptor, but evidence for altruism has been indirect. Here, we show that mixing wild-type and activated tgrB1 cells increases wild-type spore production and relegates the mutants to the altruistic stalk, whereas mixing wild-type and tgrB1-null cells increases mutant spore production and wild-type stalk production. The tgrB1-null cells cheat only on partners that carry the same tgrC1-allotype. Therefore, TgrB1 activation confers altruism whereas TgrB1 inactivation causes allotype-specific cheating, supporting the greenbeard concept and providing insight into the relationship between allorecognition, altruism, and exploitation.


Asunto(s)
Altruismo , Dictyostelium , Proteínas de la Membrana , Proteínas Protozoarias , Quimiotaxis/genética , Dictyostelium/genética , Dictyostelium/metabolismo , Dictyostelium/fisiología , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/genética , Mutación , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Transducción de Señal , Esporas Protozoarias/genética , Esporas Protozoarias/metabolismo
19.
Int Immunopharmacol ; 136: 112264, 2024 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-38810308

RESUMEN

BACKGROUND: Chemotaxis and trafficking of dendritic cells (DCs) induced by cytokine receptors are crucial steps in rheumatoid arthritis (RA) pathogenesis. C-C chemokine receptor type 5 (CCR5) plays a key role in DC movement and has been implicated in multitudinous inflammatory and immunology diseases. Thus, targeting CCR5 to suppress DC chemotaxis is considered as a potential strategy for the management of RA. METHODS: Herein, we first synthesized a new hybrid named CT3-1 which based on artesunate and isatin. Besides, we studied the regulating effectiveness of CT3-1 on bone marrow-derived DCs (BMDCs) and on collagen-induced arthritis (CIA) through RNA-seq analysis, cell function experiments in vitro and mice model in vivo. RESULTS: The results shown that CT3-1 mainly reduced CCR5 expression of immature BMDCs and importantly inhibited immature BMDC migration induced by CCR5 in vitro, with no or minor influence on other functions of DCs, such as phagocytosis and maturation. In the mouse model, CT3-1 relieved arthritis severity and inhibited CIA development. Furthermore, CT3-1 intervention decreased the expression of CCR5 in DCs and reduced the proportion of DCs in the peripheral blood of CIA mice. CONCLUSIONS: Our findings suggest that CCR5-induced chemotaxis and trafficking of immature DCs are important in RA. Targeting CCR5 and inhibiting immature DC chemotaxis may provide a novel choice for the treatment of RA and other similar autoimmune diseases. Moreover, we synthesized a new hybrid compound CT3-1 that could inhibit immature DC trafficking and effectively relieve RA by directly reducing the CCR5 expression of immature DCs.


Asunto(s)
Artesunato , Artritis Experimental , Artritis Reumatoide , Quimiotaxis , Células Dendríticas , Receptores CCR5 , Animales , Células Dendríticas/efectos de los fármacos , Células Dendríticas/inmunología , Receptores CCR5/metabolismo , Artritis Experimental/tratamiento farmacológico , Artritis Experimental/inmunología , Quimiotaxis/efectos de los fármacos , Artesunato/farmacología , Artesunato/uso terapéutico , Ratones , Artritis Reumatoide/tratamiento farmacológico , Artritis Reumatoide/inmunología , Ratones Endogámicos DBA , Masculino , Células Cultivadas , Humanos
20.
J Biosci ; 492024.
Artículo en Inglés | MEDLINE | ID: mdl-38726826

RESUMEN

Lung cancer (LC) is the leading cause of cancer-associated deaths worldwide, among which non-small-cell lung cancer (NSCLC) accounts for 80%. Stromal cell-derived factor-1 (SDF-1) inhibition results in a significant depletion of NSCLC metastasis. Additionally, SDF-1 is the only natural chemokine known to bind and activate the receptor CXCR4. Thus, we attempted to clarify the molecular mechanism of SDF-1 underlying NSCLC progression. Transwell migration, adhesion, and G-LISA assays were used to assess megakaryocytic chemotaxis in vitro and in vivo in terms of megakaryocytic migration, adherence, and RhoA activation, respectively. Western blotting was used to assess PI3K/Akt-associated protein abundances in MEG-01 cells and primary megakaryocytes under the indicated treatment. A hematology analyzer and flow cytometry were used to assess platelet counts in peripheral blood and newly formed platelet counts in Lewis LC mice under different treatments. Immunochemistry and flow cytometry were used to measure CD41+ megakaryocyte numbers in Lewis LC mouse tissue under different treatments. ELISA was used to measure serum TPO levels, and H&E staining was used to detect NSCLC metastasis.SDF-1 receptor knockdown suppressed megakaryocytic chemotaxis in Lewis LC mice. SDF-1 receptor inhibition suppressed megakaryocytic chemotaxis via the PI3K/Akt pathway. SDF-1 receptor knockdown suppressed CD41+ megakaryocyte numbers in vivo through PI3K/Akt signaling. SDF-1 receptor inhibition suppressed CD41+ megakaryocytes to hinder NSCLC metastasis. SDF-1 facilitates NSCLC metastasis by enhancing the chemoattraction of megakaryocytes via the PI3K/Akt signaling pathway, which may provide a potential new direction for seeking therapeutic plans for NSCLC.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas , Quimiocina CXCL12 , Quimiotaxis , Neoplasias Pulmonares , Megacariocitos , Transducción de Señal , Animales , Humanos , Ratones , Carcinoma de Pulmón de Células no Pequeñas/patología , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Carcinoma de Pulmón de Células no Pequeñas/genética , Línea Celular Tumoral , Movimiento Celular/genética , Quimiocina CXCL12/metabolismo , Quimiocina CXCL12/genética , Regulación Neoplásica de la Expresión Génica , Neoplasias Pulmonares/patología , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/secundario , Megacariocitos/metabolismo , Megacariocitos/patología , Metástasis de la Neoplasia , Fosfatidilinositol 3-Quinasas/metabolismo , Fosfatidilinositol 3-Quinasas/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-akt/genética , Receptores CXCR4/metabolismo , Receptores CXCR4/genética
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