Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 35
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Cell Biol ; 223(6)2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38506714

RESUMO

The extracellular matrix (ECM) serves as a scaffold for cells and plays an essential role in regulating numerous cellular processes, including cell migration and proliferation. Due to limitations in specimen preparation for conventional room-temperature electron microscopy, we lack structural knowledge on how ECM components are secreted, remodeled, and interact with surrounding cells. We have developed a 3D-ECM platform compatible with sample thinning by cryo-focused ion beam milling, the lift-out extraction procedure, and cryo-electron tomography. Our workflow implements cell-derived matrices (CDMs) grown on EM grids, resulting in a versatile tool closely mimicking ECM environments. This allows us to visualize ECM for the first time in its hydrated, native context. Our data reveal an intricate network of extracellular fibers, their positioning relative to matrix-secreting cells, and previously unresolved structural entities. Our workflow and results add to the structural atlas of the ECM, providing novel insights into its secretion and assembly.


Assuntos
Tomografia com Microscopia Eletrônica , Matriz Extracelular , Transporte Biológico , Movimento Celular , Citosol , Tomografia com Microscopia Eletrônica/métodos , Matriz Extracelular/ultraestrutura
2.
Development ; 151(4)2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38372390

RESUMO

Embryogenesis results from the coordinated activities of different signaling pathways controlling cell fate specification and morphogenesis. In vertebrate gastrulation, both Nodal and BMP signaling play key roles in germ layer specification and morphogenesis, yet their interplay to coordinate embryo patterning with morphogenesis is still insufficiently understood. Here, we took a reductionist approach using zebrafish embryonic explants to study the coordination of Nodal and BMP signaling for embryo patterning and morphogenesis. We show that Nodal signaling triggers explant elongation by inducing mesendodermal progenitors but also suppressing BMP signaling activity at the site of mesendoderm induction. Consistent with this, ectopic BMP signaling in the mesendoderm blocks cell alignment and oriented mesendoderm intercalations, key processes during explant elongation. Translating these ex vivo observations to the intact embryo showed that, similar to explants, Nodal signaling suppresses the effect of BMP signaling on cell intercalations in the dorsal domain, thus allowing robust embryonic axis elongation. These findings suggest a dual function of Nodal signaling in embryonic axis elongation by both inducing mesendoderm and suppressing BMP effects in the dorsal portion of the mesendoderm.


Assuntos
Padronização Corporal , Peixe-Zebra , Animais , Padronização Corporal/genética , Proteína Nodal/genética , Proteína Nodal/metabolismo , Morfogênese/genética , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismo , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismo , Regulação da Expressão Gênica no Desenvolvimento
3.
Faraday Discuss ; 248(0): 175-189, 2024 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-37750344

RESUMO

Singlet oxygen (1O2) formation is now recognised as a key aspect of non-aqueous oxygen redox chemistry. For identifying 1O2, chemical trapping via 9,10-dimethylanthracene (DMA) to form the endoperoxide (DMA-O2) has become the main method due to its sensitivity, selectivity, and ease of use. While DMA has been shown to be selective for 1O2, rather than forming DMA-O2 with a wide variety of potentially reactive O-containing species, false positives might hypothetically be obtained in the presence of previously overlooked species. Here, we first provide unequivocal direct spectroscopic proof via the 1O2-specific near-infrared (NIR) emission at 1270 nm for the previously proposed 1O2 formation pathways, which centre around superoxide disproportionation. We then show that peroxocarbonates, common intermediates in metal-O2 and metal carbonate electrochemistry, do not produce false-positive DMA-O2. Moreover, we identify a previously unreported 1O2-forming pathway through the reaction of CO2 with superoxide. Overall, we provide unequivocal proof for 1O2 formation in non-aqueous oxygen redox chemistry and show that chemical trapping with DMA is a reliable method to assess 1O2 formation.

4.
EMBO J ; 42(24): e114557, 2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-37987147

RESUMO

Motile cells encounter microenvironments with locally heterogeneous mechanochemical composition. Individual compositional parameters, such as chemokines and extracellular matrix pore sizes, are well known to provide guidance cues for pathfinding. However, motile cells face diverse cues at the same time, raising the question of how they respond to multiple and potentially competing signals on their paths. Here, we reveal that amoeboid cells require nuclear repositioning, termed nucleokinesis, for adaptive pathfinding in heterogeneous mechanochemical micro-environments. Using mammalian immune cells and the amoeba Dictyostelium discoideum, we discover that frequent, rapid and long-distance nucleokinesis is a basic component of amoeboid pathfinding, enabling cells to reorientate quickly between locally competing cues. Amoeboid nucleokinesis comprises a two-step polarity switch and is driven by myosin-II forces that readjust the nuclear to the cellular path. Impaired nucleokinesis distorts path adaptions and causes cellular arrest in the microenvironment. Our findings establish that nucleokinesis is required for amoeboid cell navigation. Given that many immune cells, amoebae, and some cancer cells utilize an amoeboid migration strategy, these results suggest that nucleokinesis underlies cellular navigation during unicellular biology, immunity, and disease.


Assuntos
Amoeba , Dictyostelium , Animais , Movimento Celular , Matriz Extracelular , Mamíferos
5.
J Cell Biol ; 221(12)2022 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-36214847

RESUMO

Centrosomes play a crucial role during immune cell interactions and initiation of the immune response. In proliferating cells, centrosome numbers are tightly controlled and generally limited to one in G1 and two prior to mitosis. Defects in regulating centrosome numbers have been associated with cell transformation and tumorigenesis. Here, we report the emergence of extra centrosomes in leukocytes during immune activation. Upon antigen encounter, dendritic cells pass through incomplete mitosis and arrest in the subsequent G1 phase leading to tetraploid cells with accumulated centrosomes. In addition, cell stimulation increases expression of polo-like kinase 2, resulting in diploid cells with two centrosomes in G1-arrested cells. During cell migration, centrosomes tightly cluster and act as functional microtubule-organizing centers allowing for increased persistent locomotion along gradients of chemotactic cues. Moreover, dendritic cells with extra centrosomes display enhanced secretion of inflammatory cytokines and optimized T cell responses. Together, these results demonstrate a previously unappreciated role of extra centrosomes for regular cell and tissue homeostasis.


Assuntos
Centrossomo , Células Dendríticas , Pontos de Checagem do Ciclo Celular , Movimento Celular , Centrossomo/metabolismo , Quimiotaxia , Citocinas/metabolismo , Células Dendríticas/metabolismo , Humanos , Centro Organizador dos Microtúbulos , Mitose , Proteínas Serina-Treonina Quinases/metabolismo , Linfócitos T/metabolismo
6.
Nat Immunol ; 23(8): 1246-1255, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35817845

RESUMO

Lymph nodes (LNs) comprise two main structural elements: fibroblastic reticular cells that form dedicated niches for immune cell interaction and capsular fibroblasts that build a shell around the organ. Immunological challenge causes LNs to increase more than tenfold in size within a few days. Here, we characterized the biomechanics of LN swelling on the cellular and organ scale. We identified lymphocyte trapping by influx and proliferation as drivers of an outward pressure force, causing fibroblastic reticular cells of the T-zone (TRCs) and their associated conduits to stretch. After an initial phase of relaxation, TRCs sensed the resulting strain through cell matrix adhesions, which coordinated local growth and remodeling of the stromal network. While the expanded TRC network readopted its typical configuration, a massive fibrotic reaction of the organ capsule set in and countered further organ expansion. Thus, different fibroblast populations mechanically control LN swelling in a multitier fashion.


Assuntos
Linfonodos , Células Estromais , Animais , Fibroblastos , Linfócitos , Camundongos , Camundongos Endogâmicos C57BL
7.
Dev Cell ; 57(1): 47-62.e9, 2022 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-34919802

RESUMO

When crawling through the body, leukocytes often traverse tissues that are densely packed with extracellular matrix and other cells, and this raises the question: How do leukocytes overcome compressive mechanical loads? Here, we show that the actin cortex of leukocytes is mechanoresponsive and that this responsiveness requires neither force sensing via the nucleus nor adhesive interactions with a substrate. Upon global compression of the cell body as well as local indentation of the plasma membrane, Wiskott-Aldrich syndrome protein (WASp) assembles into dot-like structures, providing activation platforms for Arp2/3 nucleated actin patches. These patches locally push against the external load, which can be obstructing collagen fibers or other cells, and thereby create space to facilitate forward locomotion. We show in vitro and in vivo that this WASp function is rate limiting for ameboid leukocyte migration in dense but not in loose environments and is required for trafficking through diverse tissues such as skin and lymph nodes.


Assuntos
Actinas/fisiologia , Leucócitos/fisiologia , Proteína da Síndrome de Wiskott-Aldrich/metabolismo , Complexo 2-3 de Proteínas Relacionadas à Actina/metabolismo , Complexo 2-3 de Proteínas Relacionadas à Actina/fisiologia , Proteína 3 Relacionada a Actina/metabolismo , Actinas/metabolismo , Animais , Fenômenos Biomecânicos/fisiologia , Linhagem Celular , Movimento Celular/fisiologia , Proteínas do Citoesqueleto/metabolismo , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ligação Proteica/fisiologia , Proteína da Síndrome de Wiskott-Aldrich/genética
8.
Science ; 373(6550): 82-88, 2021 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-34210881

RESUMO

A semiconducting nanowire fully wrapped by a superconducting shell has been proposed as a platform for obtaining Majorana modes at small magnetic fields. In this study, we demonstrate that the appearance of subgap states in such structures is actually governed by the junction region in tunneling spectroscopy measurements and not the full-shell nanowire itself. Short tunneling regions never show subgap states, whereas longer junctions always do. This can be understood in terms of quantum dots forming in the junction and hosting Andreev levels in the Yu-Shiba-Rusinov regime. The intricate magnetic field dependence of the Andreev levels, through both the Zeeman and Little-Parks effects, may result in robust zero-bias peaks-features that could be easily misinterpreted as originating from Majorana zero modes but are unrelated to topological superconductivity.

9.
ACS Appl Mater Interfaces ; 13(30): 35545-35560, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34283577

RESUMO

Attachment of adhesive molecules on cell culture surfaces to restrict cell adhesion to defined areas and shapes has been vital for the progress of in vitro research. In currently existing patterning methods, a combination of pattern properties such as stability, precision, specificity, high-throughput outcome, and spatiotemporal control is highly desirable but challenging to achieve. Here, we introduce a versatile and high-throughput covalent photoimmobilization technique, comprising a light-dose-dependent patterning step and a subsequent functionalization of the pattern via click chemistry. This two-step process is feasible on arbitrary surfaces and allows for generation of sustainable patterns and gradients. The method is validated in different biological systems by patterning adhesive ligands on cell-repellent surfaces, thereby constraining the growth and migration of cells to the designated areas. We then implement a sequential photopatterning approach by adding a second switchable patterning step, allowing for spatiotemporal control over two distinct surface patterns. As a proof of concept, we reconstruct the dynamics of the tip/stalk cell switch during angiogenesis. Our results show that the spatiotemporal control provided by our "sequential photopatterning" system is essential for mimicking dynamic biological processes and that our innovative approach has great potential for further applications in cell science.


Assuntos
Adesão Celular/efeitos dos fármacos , Técnicas de Cultura de Células/métodos , Movimento Celular/fisiologia , Corantes Fluorescentes/química , Neovascularização Fisiológica/fisiologia , Animais , Adesão Celular/fisiologia , Linhagem Celular Tumoral , Química Click , Reagentes de Ligações Cruzadas/química , Corantes Fluorescentes/efeitos da radiação , Humanos , Proteínas Imobilizadas/química , Ligantes , Camundongos , Células NIH 3T3 , Peptídeos/química , Estudo de Prova de Conceito , Propriedades de Superfície , Peixe-Zebra
10.
Curr Biol ; 31(9): 1918-1930.e5, 2021 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-33705718

RESUMO

Polar subcellular localization of the PIN exporters of the phytohormone auxin is a key determinant of directional, intercellular auxin transport and thus a central topic of both plant cell and developmental biology. Arabidopsis mutants lacking PID, a kinase that phosphorylates PINs, or the MAB4/MEL proteins of unknown molecular function display PIN polarity defects and phenocopy pin mutants, but mechanistic insights into how these factors convey PIN polarity are missing. Here, by combining protein biochemistry with quantitative live-cell imaging, we demonstrate that PINs, MAB4/MELs, and AGC kinases interact in the same complex at the plasma membrane. MAB4/MELs are recruited to the plasma membrane by the PINs and in concert with the AGC kinases maintain PIN polarity through limiting lateral diffusion-based escape of PINs from the polar domain. The PIN-MAB4/MEL-PID protein complex has self-reinforcing properties thanks to positive feedback between AGC kinase-mediated PIN phosphorylation and MAB4/MEL recruitment. We thus uncover the molecular mechanism by which AGC kinases and MAB4/MEL proteins regulate PIN localization and plant development.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Polaridade Celular , Regulação da Expressão Gênica de Plantas , Ácidos Indolacéticos , Proteínas de Membrana Transportadoras/genética , Células Vegetais/metabolismo , Raízes de Plantas/metabolismo
11.
Front Immunol ; 12: 630002, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33717158

RESUMO

Gradients of chemokines and growth factors guide migrating cells and morphogenetic processes. Migration of antigen-presenting dendritic cells from the interstitium into the lymphatic system is dependent on chemokine CCL21, which is secreted by endothelial cells of the lymphatic capillary, binds heparan sulfates and forms gradients decaying into the interstitium. Despite the importance of CCL21 gradients, and chemokine gradients in general, the mechanisms of gradient formation are unclear. Studies on fibroblast growth factors have shown that limited diffusion is crucial for gradient formation. Here, we used the mouse dermis as a model tissue to address the necessity of CCL21 anchoring to lymphatic capillary heparan sulfates in the formation of interstitial CCL21 gradients. Surprisingly, the absence of lymphatic endothelial heparan sulfates resulted only in a modest decrease of CCL21 levels at the lymphatic capillaries and did neither affect interstitial CCL21 gradient shape nor dendritic cell migration toward lymphatic capillaries. Thus, heparan sulfates at the level of the lymphatic endothelium are dispensable for the formation of a functional CCL21 gradient.


Assuntos
Quimiocina CCL21/metabolismo , Células Dendríticas/imunologia , Derme/imunologia , Endotélio Linfático/imunologia , Heparitina Sulfato/metabolismo , Vasos Linfáticos/patologia , Animais , Células Cultivadas , Quimiotaxia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores CCR7/genética
12.
J Cell Biol ; 220(4)2021 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-33533935

RESUMO

Dendritic cells (DCs) are crucial for the priming of naive T cells and the initiation of adaptive immunity. Priming is initiated at a heterologous cell-cell contact, the immunological synapse (IS). While it is established that F-actin dynamics regulates signaling at the T cell side of the contact, little is known about the cytoskeletal contribution on the DC side. Here, we show that the DC actin cytoskeleton is decisive for the formation of a multifocal synaptic structure, which correlates with T cell priming efficiency. DC actin at the IS appears in transient foci that are dynamized by the WAVE regulatory complex (WRC). The absence of the WRC in DCs leads to stabilized contacts with T cells, caused by an increase in ICAM1-integrin-mediated cell-cell adhesion. This results in lower numbers of activated and proliferating T cells, demonstrating an important role for DC actin in the regulation of immune synapse functionality.


Assuntos
Actinas/imunologia , Comunicação Celular/imunologia , Células Dendríticas/imunologia , Sinapses Imunológicas/imunologia , Linfócitos T/imunologia , Actinas/genética , Animais , Adesão Celular/genética , Adesão Celular/imunologia , Comunicação Celular/genética , Proliferação de Células/genética , Feminino , Sinapses Imunológicas/genética , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/imunologia , Masculino , Camundongos , Camundongos Knockout
13.
Plant Sci ; 303: 110750, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33487339

RESUMO

Auxin is a major plant growth regulator, but current models on auxin perception and signaling cannot explain the whole plethora of auxin effects, in particular those associated with rapid responses. A possible candidate for a component of additional auxin perception mechanisms is the AUXIN BINDING PROTEIN 1 (ABP1), whose function in planta remains unclear. Here we combined expression analysis with gain- and loss-of-function approaches to analyze the role of ABP1 in plant development. ABP1 shows a broad expression largely overlapping with, but not regulated by, transcriptional auxin response activity. Furthermore, ABP1 activity is not essential for the transcriptional auxin signaling. Genetic in planta analysis revealed that abp1 loss-of-function mutants show largely normal development with minor defects in bolting. On the other hand, ABP1 gain-of-function alleles show a broad range of growth and developmental defects, including root and hypocotyl growth and bending, lateral root and leaf development, bolting, as well as response to heat stress. At the cellular level, ABP1 gain-of-function leads to impaired auxin effect on PIN polar distribution and affects BFA-sensitive PIN intracellular aggregation. The gain-of-function analysis suggests a broad, but still mechanistically unclear involvement of ABP1 in plant development, possibly masked in abp1 loss-of-function mutants by a functional redundancy.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/crescimento & desenvolvimento , Proteínas de Plantas/fisiologia , Receptores de Superfície Celular/fisiologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Hipocótilo/crescimento & desenvolvimento , Hipocótilo/metabolismo , Ácidos Indolacéticos/metabolismo , Microscopia Confocal , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/fisiologia , Proteínas de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Protoplastos/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Superfície Celular/metabolismo
14.
J Struct Biol ; 212(3): 107633, 2020 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-32987119

RESUMO

Cryo-electron microscopy (cryo-EM) of cellular specimens provides insights into biological processes and structures within a native context. However, a major challenge still lies in the efficient and reproducible preparation of adherent cells for subsequent cryo-EM analysis. This is due to the sensitivity of many cellular specimens to the varying seeding and culturing conditions required for EM experiments, the often limited amount of cellular material and also the fragility of EM grids and their substrate. Here, we present low-cost and reusable 3D printed grid holders, designed to improve specimen preparation when culturing challenging cellular samples directly on grids. The described grid holders increase cell culture reproducibility and throughput, and reduce the resources required for cell culturing. We show that grid holders can be integrated into various cryo-EM workflows, including micro-patterning approaches to control cell seeding on grids, and for generating samples for cryo-focused ion beam milling and cryo-electron tomography experiments. Their adaptable design allows for the generation of specialized grid holders customized to a large variety of applications.


Assuntos
Técnicas de Cultura de Células/métodos , Microscopia Crioeletrônica/métodos , Manejo de Espécimes/métodos , Impressão Tridimensional , Reprodutibilidade dos Testes , Fluxo de Trabalho
15.
Nature ; 582(7813): 582-585, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32581372

RESUMO

Eukaryotic cells migrate by coupling the intracellular force of the actin cytoskeleton to the environment. While force coupling is usually mediated by transmembrane adhesion receptors, especially those of the integrin family, amoeboid cells such as leukocytes can migrate extremely fast despite very low adhesive forces1. Here we show that leukocytes cannot only migrate under low adhesion but can also transmit forces in the complete absence of transmembrane force coupling. When confined within three-dimensional environments, they use the topographical features of the substrate to propel themselves. Here the retrograde flow of the actin cytoskeleton follows the texture of the substrate, creating retrograde shear forces that are sufficient to drive the cell body forwards. Notably, adhesion-dependent and adhesion-independent migration are not mutually exclusive, but rather are variants of the same principle of coupling retrograde actin flow to the environment and thus can potentially operate interchangeably and simultaneously. As adhesion-free migration is independent of the chemical composition of the environment, it renders cells completely autonomous in their locomotive behaviour.


Assuntos
Citoesqueleto de Actina/metabolismo , Movimento Celular , Microambiente Celular , Linfócitos T/citologia , Actinas/metabolismo , Animais , Adesão Celular , Linhagem Celular , Humanos , Camundongos , Linfócitos T/metabolismo , Talina/deficiência
16.
J Cell Biol ; 219(6)2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32379884

RESUMO

Cells navigating through complex tissues face a fundamental challenge: while multiple protrusions explore different paths, the cell needs to avoid entanglement. How a cell surveys and then corrects its own shape is poorly understood. Here, we demonstrate that spatially distinct microtubule dynamics regulate amoeboid cell migration by locally promoting the retraction of protrusions. In migrating dendritic cells, local microtubule depolymerization within protrusions remote from the microtubule organizing center triggers actomyosin contractility controlled by RhoA and its exchange factor Lfc. Depletion of Lfc leads to aberrant myosin localization, thereby causing two effects that rate-limit locomotion: (1) impaired cell edge coordination during path finding and (2) defective adhesion resolution. Compromised shape control is particularly hindering in geometrically complex microenvironments, where it leads to entanglement and ultimately fragmentation of the cell body. We thus demonstrate that microtubules can act as a proprioceptive device: they sense cell shape and control actomyosin retraction to sustain cellular coherence.


Assuntos
Actomiosina/metabolismo , Movimento Celular/fisiologia , Células Dendríticas/citologia , Centro Organizador dos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Fatores de Troca de Nucleotídeo Guanina Rho/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo , Animais , Adesão Celular/fisiologia , Forma Celular/fisiologia , Células Cultivadas , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/metabolismo , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Centro Organizador dos Microtúbulos/efeitos dos fármacos , Microtúbulos/efeitos dos fármacos , Nocodazol/farmacologia , Ligação Proteica , Fatores de Troca de Nucleotídeo Guanina Rho/deficiência , Fatores de Troca de Nucleotídeo Guanina Rho/genética
17.
Elife ; 92020 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-32250246

RESUMO

Embryonic stem cell cultures are thought to self-organize into embryoid bodies, able to undergo symmetry-breaking, germ layer specification and even morphogenesis. Yet, it is unclear how to reconcile this remarkable self-organization capacity with classical experiments demonstrating key roles for extrinsic biases by maternal factors and/or extraembryonic tissues in embryogenesis. Here, we show that zebrafish embryonic tissue explants, prepared prior to germ layer induction and lacking extraembryonic tissues, can specify all germ layers and form a seemingly complete mesendoderm anlage. Importantly, explant organization requires polarized inheritance of maternal factors from dorsal-marginal regions of the blastoderm. Moreover, induction of endoderm and head-mesoderm, which require peak Nodal-signaling levels, is highly variable in explants, reminiscent of embryos with reduced Nodal signals from the extraembryonic tissues. Together, these data suggest that zebrafish explants do not undergo bona fide self-organization, but rather display features of genetically encoded self-assembly, where intrinsic genetic programs control the emergence of order.


Assuntos
Desenvolvimento Embrionário/fisiologia , Peixe-Zebra/embriologia , Animais , Blastoderma/transplante , Padronização Corporal , Desenvolvimento Embrionário/genética , Mesoderma/embriologia , Morfogênese , Proteína Nodal/fisiologia , Transdução de Sinais/fisiologia
18.
Nature ; 568(7753): 546-550, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30944468

RESUMO

During metazoan development, immune surveillance and cancer dissemination, cells migrate in complex three-dimensional microenvironments1-3. These spaces are crowded by cells and extracellular matrix, generating mazes with differently sized gaps that are typically smaller than the diameter of the migrating cell4,5. Most mesenchymal and epithelial cells and some-but not all-cancer cells actively generate their migratory path using pericellular tissue proteolysis6. By contrast, amoeboid cells such as leukocytes use non-destructive strategies of locomotion7, raising the question how these extremely fast cells navigate through dense tissues. Here we reveal that leukocytes sample their immediate vicinity for large pore sizes, and are thereby able to choose the path of least resistance. This allows them to circumnavigate local obstacles while effectively following global directional cues such as chemotactic gradients. Pore-size discrimination is facilitated by frontward positioning of the nucleus, which enables the cells to use their bulkiest compartment as a mechanical gauge. Once the nucleus and the closely associated microtubule organizing centre pass the largest pore, cytoplasmic protrusions still lingering in smaller pores are retracted. These retractions are coordinated by dynamic microtubules; when microtubules are disrupted, migrating cells lose coherence and frequently fragment into migratory cytoplasmic pieces. As nuclear positioning in front of the microtubule organizing centre is a typical feature of amoeboid migration, our findings link the fundamental organization of cellular polarity to the strategy of locomotion.


Assuntos
Movimento Celular/fisiologia , Núcleo Celular/metabolismo , Polaridade Celular/fisiologia , Animais , Linhagem Celular , Células Cultivadas , Quimiotaxia/fisiologia , Feminino , Humanos , Masculino , Camundongos Endogâmicos C57BL , Centro Organizador dos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Porosidade
19.
Nat Immunol ; 19(6): 606-616, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29777221

RESUMO

Although much is known about the physiological framework of T cell motility, and numerous rate-limiting molecules have been identified through loss-of-function approaches, an integrated functional concept of T cell motility is lacking. Here, we used in vivo precision morphometry together with analysis of cytoskeletal dynamics in vitro to deconstruct the basic mechanisms of T cell migration within lymphatic organs. We show that the contributions of the integrin LFA-1 and the chemokine receptor CCR7 are complementary rather than positioned in a linear pathway, as they are during leukocyte extravasation from the blood vasculature. Our data demonstrate that CCR7 controls cortical actin flows, whereas integrins mediate substrate friction that is sufficient to drive locomotion in the absence of considerable surface adhesions and plasma membrane flux.


Assuntos
Actinas/imunologia , Quimiotaxia de Leucócito/imunologia , Antígeno-1 Associado à Função Linfocitária/imunologia , Receptores CCR7/imunologia , Linfócitos T/imunologia , Actinas/metabolismo , Animais , Quimiocinas/imunologia , Quimiocinas/metabolismo , Fricção , Integrinas/imunologia , Integrinas/metabolismo , Linfonodos , Antígeno-1 Associado à Função Linfocitária/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores CCR7/metabolismo , Linfócitos T/metabolismo
20.
J Cell Biol ; 217(6): 2205-2221, 2018 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-29650776

RESUMO

Lymphatic endothelial cells (LECs) release extracellular chemokines to guide the migration of dendritic cells. In this study, we report that LECs also release basolateral exosome-rich endothelial vesicles (EEVs) that are secreted in greater numbers in the presence of inflammatory cytokines and accumulate in the perivascular stroma of small lymphatic vessels in human chronic inflammatory diseases. Proteomic analyses of EEV fractions identified >1,700 cargo proteins and revealed a dominant motility-promoting protein signature. In vitro and ex vivo EEV fractions augmented cellular protrusion formation in a CX3CL1/fractalkine-dependent fashion and enhanced the directional migratory response of human dendritic cells along guidance cues. We conclude that perilymphatic LEC exosomes enhance exploratory behavior and thus promote directional migration of CX3CR1-expressing cells in complex tissue environments.


Assuntos
Movimento Celular , Células Dendríticas/citologia , Células Dendríticas/metabolismo , Exossomos/metabolismo , Vasos Linfáticos/metabolismo , Animais , Linhagem Celular Tumoral , Extensões da Superfície Celular/metabolismo , Microambiente Celular , Quimiocina CX3CL1/metabolismo , Colágeno/metabolismo , Sinais (Psicologia) , Células Endoteliais/metabolismo , Células Endoteliais/ultraestrutura , Exossomos/ultraestrutura , Humanos , Inflamação/patologia , Rim/metabolismo , Rim/patologia , Masculino , Camundongos , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Proteômica , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Fator de Necrose Tumoral alfa/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...