RESUMEN
The lymphatic vasculature is not considered a formal part of the immune system, but it is critical to immunity. One of its major roles is in the coordination of the trafficking of antigen and immune cells. However, other roles in immunity are emerging. Lymphatic endothelial cells, for example, directly present antigen or express factors that greatly influence the local environment. We cover these topics herein and discuss how other properties of the lymphatic vasculature, such as mechanisms of lymphatic contraction (which immunologists traditionally do not take into account), are nonetheless integral in the immune system. Much is yet unknown, and this nascent subject is ripe for exploration. We argue that to consider the impact of lymphatic biology in any given immunological interaction is a key step toward integrating immunology with organ physiology and ultimately many complex pathologies.
Asunto(s)
Células Endoteliales/inmunología , Sistema Inmunológico , Inmunidad , Sistema Linfático/inmunología , Vasos Linfáticos/fisiología , Animales , Presentación de Antígeno , Humanos , Metabolismo de los LípidosRESUMEN
Tissue folds are structural motifs critical to organ function. In the intestine, bending of a flat epithelium into a periodic pattern of folds gives rise to villi, finger-like protrusions that enable nutrient absorption. However, the molecular and mechanical processes driving villus morphogenesis remain unclear. Here, we identify an active mechanical mechanism that simultaneously patterns and folds the intestinal epithelium to initiate villus formation. At the cellular level, we find that PDGFRA+ subepithelial mesenchymal cells generate myosin II-dependent forces sufficient to produce patterned curvature in neighboring tissue interfaces. This symmetry-breaking process requires altered cell and extracellular matrix interactions that are enabled by matrix metalloproteinase-mediated tissue fluidization. Computational models, together with in vitro and in vivo experiments, revealed that these cellular features manifest at the tissue level as differences in interfacial tensions that promote mesenchymal aggregation and interface bending through a process analogous to the active dewetting of a thin liquid film.
Asunto(s)
Matriz Extracelular , Mucosa Intestinal , Animales , Ratones , Mucosa Intestinal/metabolismo , Mucosa Intestinal/citología , Matriz Extracelular/metabolismo , Miosina Tipo II/metabolismo , Mesodermo/metabolismo , Mesodermo/citología , Células Madre Mesenquimatosas/metabolismo , Células Madre Mesenquimatosas/citología , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/metabolismo , Morfogénesis , Metaloproteinasas de la Matriz/metabolismoRESUMEN
The choroid plexus (ChP) is a vital brain barrier and source of cerebrospinal fluid (CSF). Here, we use longitudinal two-photon imaging in awake mice and single-cell transcriptomics to elucidate the mechanisms of ChP regulation of brain inflammation. We used intracerebroventricular injections of lipopolysaccharides (LPS) to model meningitis in mice and observed that neutrophils and monocytes accumulated in the ChP stroma and surged across the epithelial barrier into the CSF. Bi-directional recruitment of monocytes from the periphery and, unexpectedly, macrophages from the CSF to the ChP helped eliminate neutrophils and repair the barrier. Transcriptomic analyses detailed the molecular steps accompanying this process and revealed that ChP epithelial cells transiently specialize to nurture immune cells, coordinating their recruitment, survival, and differentiation as well as regulation of the tight junctions that control the permeability of the ChP brain barrier. Collectively, we provide a mechanistic understanding and a comprehensive roadmap of neuroinflammation at the ChP brain barrier.
RESUMEN
Olfactory sensory neurons (OSNs) convert the stochastic choice of one of >1,000 olfactory receptor (OR) genes into precise and stereotyped axon targeting of OR-specific glomeruli in the olfactory bulb. Here, we show that the PERK arm of the unfolded protein response (UPR) regulates both the glomerular coalescence of like axons and the specificity of their projections. Subtle differences in OR protein sequences lead to distinct patterns of endoplasmic reticulum (ER) stress during OSN development, converting OR identity into distinct gene expression signatures. We identify the transcription factor Ddit3 as a key effector of PERK signaling that maps OR-dependent ER stress patterns to the transcriptional regulation of axon guidance and cell-adhesion genes, instructing targeting precision. Our results extend the known functions of the UPR from a quality-control pathway that protects cells from misfolded proteins to a sensor of cellular identity that interprets physiological states to direct axon wiring.
Asunto(s)
Axones/metabolismo , Estrés del Retículo Endoplásmico , Receptores Odorantes , Animales , Ratones , Bulbo Olfatorio , Neuronas Receptoras Olfatorias/metabolismo , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Factores de Transcripción/metabolismoRESUMEN
Gasdermins are a family of structurally related proteins originally described for their role in pyroptosis. Gasdermin B (GSDMB) is currently the least studied, and while its association with genetic susceptibility to chronic mucosal inflammatory disorders is well established, little is known about its functional relevance during active disease states. Herein, we report increased GSDMB in inflammatory bowel disease, with single-cell analysis identifying epithelial specificity to inflamed colonocytes/crypt top colonocytes. Surprisingly, mechanistic experiments and transcriptome profiling reveal lack of inherent GSDMB-dependent pyroptosis in activated epithelial cells and organoids but instead point to increased proliferation and migration during in vitro wound closure, which arrests in GSDMB-deficient cells that display hyper-adhesiveness and enhanced formation of vinculin-based focal adhesions dependent on PDGF-A-mediated FAK phosphorylation. Importantly, carriage of disease-associated GSDMB SNPs confers functional defects, disrupting epithelial restitution/repair, which, altogether, establishes GSDMB as a critical factor for restoration of epithelial barrier function and the resolution of inflammation.
Asunto(s)
Células Epiteliales/metabolismo , Células Epiteliales/patología , Enfermedades Inflamatorias del Intestino/metabolismo , Enfermedades Inflamatorias del Intestino/patología , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Piroptosis , Secuencia de Bases , Estudios de Casos y Controles , Adhesión Celular/efectos de los fármacos , Adhesión Celular/genética , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Movimiento Celular/efectos de los fármacos , Movimiento Celular/genética , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , Células Epiteliales/efectos de los fármacos , Proteína-Tirosina Quinasas de Adhesión Focal/metabolismo , Células HEK293 , Células HT29 , Humanos , Enfermedades Inflamatorias del Intestino/genética , Metotrexato/farmacología , Mutación/genética , Fosforilación/efectos de los fármacos , Polimorfismo de Nucleótido Simple/genética , Piroptosis/efectos de los fármacos , Piroptosis/genética , Reproducibilidad de los Resultados , Transcriptoma/efectos de los fármacos , Transcriptoma/genética , Regulación hacia Arriba/efectos de los fármacos , Cicatrización de Heridas/efectos de los fármacos , Cicatrización de Heridas/genéticaRESUMEN
The uterine lining (endometrium) regenerates repeatedly over the life span as part of its normal physiology. Substantial portions of the endometrium are shed during childbirth (parturition) and, in some species, menstruation, but the tissue is rapidly rebuilt without scarring, rendering it a powerful model of regeneration in mammals. Nonetheless, following some assaults, including medical procedures and infections, the endometrium fails to regenerate and instead forms scars that may interfere with normal endometrial function and contribute to infertility. Thus, the endometrium provides an exceptional platform to answer a central question of regenerative medicine: Why do some systems regenerate while others scar? Here, we review our current understanding of diverse endometrial disruption events in humans, nonhuman primates, and rodents, and the associated mechanisms of regenerative success and failure. Elucidating the determinants of these disparate repair processes promises insights into fundamental mechanisms of mammalian regeneration with substantial implications for reproductive health.
Asunto(s)
Endometrio , Útero , Femenino , Animales , Humanos , Endometrio/patología , Endometrio/fisiología , Útero/patología , Útero/fisiología , Fibrosis , MamíferosRESUMEN
Multicellular organisms generate tissues of diverse shapes and functions from cells and extracellular matrices. Their adhesion molecules mediate cell-cell and cell-matrix interactions, which not only play crucial roles in maintaining tissue integrity but also serve as key regulators of tissue morphogenesis. Cells constantly probe their environment to make decisions: They integrate chemical and mechanical information from the environment via diffusible ligand- or adhesion-based signaling to decide whether to release specific signaling molecules or enzymes, to divide or differentiate, to move away or stay, or even whether to live or die. These decisions in turn modify their environment, including the chemical nature and mechanical properties of the extracellular matrix. Tissue morphology is the physical manifestation of the remodeling of cells and matrices by their historical biochemical and biophysical landscapes. We review our understanding of matrix and adhesion molecules in tissue morphogenesis, with an emphasis on key physical interactions that drive morphogenesis.
RESUMEN
Many embryonic organs undergo epithelial morphogenesis to form tree-like hierarchical structures. However, it remains unclear what drives the budding and branching of stratified epithelia, such as in the embryonic salivary gland and pancreas. Here, we performed live-organ imaging of mouse embryonic salivary glands at single-cell resolution to reveal that budding morphogenesis is driven by expansion and folding of a distinct epithelial surface cell sheet characterized by strong cell-matrix adhesions and weak cell-cell adhesions. Profiling of single-cell transcriptomes of this epithelium revealed spatial patterns of transcription underlying these cell adhesion differences. We then synthetically reconstituted budding morphogenesis by experimentally suppressing E-cadherin expression and inducing basement membrane formation in 3D spheroid cultures of engineered cells, which required ß1-integrin-mediated cell-matrix adhesion for successful budding. Thus, stratified epithelial budding, the key first step of branching morphogenesis, is driven by an overall combination of strong cell-matrix adhesion and weak cell-cell adhesion by peripheral epithelial cells.
Asunto(s)
Uniones Célula-Matriz/metabolismo , Morfogénesis , Animales , Membrana Basal/metabolismo , Adhesión Celular , División Celular , Movimiento Celular , Rastreo Celular , Embrión de Mamíferos/citología , Células Epiteliales/citología , Células Epiteliales/metabolismo , Epitelio , Regulación del Desarrollo de la Expresión Génica , Células HEK293 , Humanos , Integrinas/metabolismo , Ratones , Modelos Biológicos , Glándulas Salivales/citología , Glándulas Salivales/embriología , Glándulas Salivales/metabolismo , Transcriptoma/genéticaRESUMEN
We have produced gene expression profiles of all 302 neurons of the C. elegans nervous system that match the single-cell resolution of its anatomy and wiring diagram. Our results suggest that individual neuron classes can be solely identified by combinatorial expression of specific gene families. For example, each neuron class expresses distinct codes of â¼23 neuropeptide genes and â¼36 neuropeptide receptors, delineating a complex and expansive "wireless" signaling network. To demonstrate the utility of this comprehensive gene expression catalog, we used computational approaches to (1) identify cis-regulatory elements for neuron-specific gene expression and (2) reveal adhesion proteins with potential roles in process placement and synaptic specificity. Our expression data are available at https://cengen.org and can be interrogated at the web application CengenApp. We expect that this neuron-specific directory of gene expression will spur investigations of underlying mechanisms that define anatomy, connectivity, and function throughout the C. elegans nervous system.
Asunto(s)
Caenorhabditis elegans/metabolismo , Sistema Nervioso/metabolismo , Animales , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Colorantes Fluorescentes/metabolismo , Regulación del Desarrollo de la Expresión Génica , Genes Reporteros , Larva/metabolismo , Neuronas/metabolismo , Neuropéptidos/genética , Neuropéptidos/metabolismo , Motivos de Nucleótidos/genética , RNA-Seq , Secuencias Reguladoras de Ácidos Nucleicos/genética , Transducción de Señal/genética , Factores de Transcripción/metabolismo , Transcripción GenéticaRESUMEN
We describe an approach to study the conformation of individual proteins during single particle tracking (SPT) in living cells. "Binder/tag" is based on incorporation of a 7-mer peptide (the tag) into a protein where its solvent exposure is controlled by protein conformation. Only upon exposure can the peptide specifically interact with a reporter protein (the binder). Thus, simple fluorescence localization reflects protein conformation. Through direct excitation of bright dyes, the trajectory and conformation of individual proteins can be followed. Simple protein engineering provides highly specific biosensors suitable for SPT and FRET. We describe tagSrc, tagFyn, tagSyk, tagFAK, and an orthogonal binder/tag pair. SPT showed slowly diffusing islands of activated Src within Src clusters and dynamics of activation in adhesions. Quantitative analysis and stochastic modeling revealed in vivo Src kinetics. The simplicity of binder/tag can provide access to diverse proteins.
Asunto(s)
Técnicas Biosensibles , Péptidos/química , Imagen Individual de Molécula , Animales , Adhesión Celular , Línea Celular , Supervivencia Celular , Embrión de Mamíferos/citología , Activación Enzimática , Fibroblastos/metabolismo , Transferencia Resonante de Energía de Fluorescencia , Humanos , Cinética , Ratones , Nanopartículas/química , Conformación Proteica , Familia-src Quinasas/metabolismoRESUMEN
Embryo morphogenesis is impacted by dynamic changes in tissue material properties, which have been proposed to occur via processes akin to phase transitions (PTs). Here, we show that rigidity percolation provides a simple and robust theoretical framework to predict material/structural PTs of embryonic tissues from local cell connectivity. By using percolation theory, combined with directly monitoring dynamic changes in tissue rheology and cell contact mechanics, we demonstrate that the zebrafish blastoderm undergoes a genuine rigidity PT, brought about by a small reduction in adhesion-dependent cell connectivity below a critical value. We quantitatively predict and experimentally verify hallmarks of PTs, including power-law exponents and associated discontinuities of macroscopic observables. Finally, we show that this uniform PT depends on blastoderm cells undergoing meta-synchronous divisions causing random and, consequently, uniform changes in cell connectivity. Collectively, our theoretical and experimental findings reveal the structural basis of material PTs in an organismal context.
Asunto(s)
Embrión no Mamífero/fisiología , Desarrollo Embrionario , Animales , Blastodermo/citología , Blastodermo/fisiología , Cadherinas/antagonistas & inhibidores , Cadherinas/genética , Cadherinas/metabolismo , Adhesión Celular , Embrión no Mamífero/citología , Morfolinos/metabolismo , Reología , Viscosidad , Pez Cebra/crecimiento & desarrolloRESUMEN
RTN4-binding proteins were widely studied as "NoGo" receptors, but their physiological interactors and roles remain elusive. Similarly, BAI adhesion-GPCRs were associated with numerous activities, but their ligands and functions remain unclear. Using unbiased approaches, we observed an unexpected convergence: RTN4 receptors are high-affinity ligands for BAI adhesion-GPCRs. A single thrombospondin type 1-repeat (TSR) domain of BAIs binds to the leucine-rich repeat domain of all three RTN4-receptor isoforms with nanomolar affinity. In the 1.65 Å crystal structure of the BAI1/RTN4-receptor complex, C-mannosylation of tryptophan and O-fucosylation of threonine in the BAI TSR-domains creates a RTN4-receptor/BAI interface shaped by unusual glycoconjugates that enables high-affinity interactions. In human neurons, RTN4 receptors regulate dendritic arborization, axonal elongation, and synapse formation by differential binding to glial versus neuronal BAIs, thereby controlling neural network activity. Thus, BAI binding to RTN4/NoGo receptors represents a receptor-ligand axis that, enabled by rare post-translational modifications, controls development of synaptic circuits.
Asunto(s)
Inhibidores de la Angiogénesis/metabolismo , Encéfalo/metabolismo , Neurogénesis , Neuronas/metabolismo , Proteínas Nogo/metabolismo , Receptores Nogo/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Adipoquinas/metabolismo , Secuencia de Aminoácidos , Animales , Axones/metabolismo , Adhesión Celular , Moléculas de Adhesión Celular Neuronal/metabolismo , Complemento C1q/metabolismo , Dendritas/metabolismo , Glicosilación , Células HEK293 , Células Madre Embrionarias Humanas/metabolismo , Humanos , Ligandos , Ratones Endogámicos C57BL , Red Nerviosa/metabolismo , Polisacáridos/metabolismo , Unión Proteica , Dominios Proteicos , Eliminación de Secuencia , Sinapsis/metabolismo , Transmisión Sináptica/fisiologíaRESUMEN
Since the proposal of the differential adhesion hypothesis, scientists have been fascinated by how cell adhesion mediates cellular self-organization to form spatial patterns during development. The search for molecular tool kits with homophilic binding specificity resulted in a diverse repertoire of adhesion molecules. Recent understanding of the dominant role of cortical tension over adhesion binding redirects the focus of differential adhesion studies to the signaling function of adhesion proteins to regulate actomyosin contractility. The broader framework of differential interfacial tension encompasses both adhesion and nonadhesion molecules, sharing the common function of modulating interfacial tension during cell sorting to generate diverse tissue patterns. Robust adhesion-based patterning requires close coordination between morphogen signaling, cell fate decisions, and changes in adhesion. Current advances in bridging theoretical and experimental approaches present exciting opportunities to understand molecular, cellular, and tissue dynamics during adhesion-based tissue patterning across multiple time and length scales.
Asunto(s)
Citoesqueleto de Actina , Actomiosina , Adhesión CelularRESUMEN
Teneurins are ancient metazoan cell adhesion receptors that control brain development and neuronal wiring in higher animals. The extracellular C terminus binds the adhesion GPCR Latrophilin, forming a trans-cellular complex with synaptogenic functions. However, Teneurins, Latrophilins, and FLRT proteins are also expressed during murine cortical cell migration at earlier developmental stages. Here, we present crystal structures of Teneurin-Latrophilin complexes that reveal how the lectin and olfactomedin domains of Latrophilin bind across a spiraling beta-barrel domain of Teneurin, the YD shell. We couple structure-based protein engineering to biophysical analysis, cell migration assays, and in utero electroporation experiments to probe the importance of the interaction in cortical neuron migration. We show that binding of Latrophilins to Teneurins and FLRTs directs the migration of neurons using a contact repulsion-dependent mechanism. The effect is observed with cell bodies and small neurites rather than their processes. The results exemplify how a structure-encoded synaptogenic protein complex is also used for repulsive cell guidance.
Asunto(s)
Proteínas del Tejido Nervioso/ultraestructura , Receptores de Péptidos/metabolismo , Tenascina/metabolismo , Animales , Adhesión Celular/fisiología , Cristalografía por Rayos X/métodos , Células HEK293 , Humanos , Células K562 , Proteínas Repetidas Ricas en Leucina , Glicoproteínas de Membrana/metabolismo , Glicoproteínas de Membrana/ultraestructura , Proteínas de la Membrana/metabolismo , Proteínas de la Membrana/ultraestructura , Ratones , Ratones Endogámicos C57BL/embriología , Proteínas del Tejido Nervioso/metabolismo , Neuritas/metabolismo , Neurogénesis/fisiología , Neuronas/metabolismo , Complejo GPIb-IX de Glicoproteína Plaquetaria/metabolismo , Complejo GPIb-IX de Glicoproteína Plaquetaria/ultraestructura , Unión Proteica/fisiología , Proteínas/metabolismo , Proteínas/ultraestructura , Receptores de Superficie Celular/metabolismo , Receptores de Péptidos/ultraestructura , Sinapsis/metabolismo , Tenascina/ultraestructuraRESUMEN
Arthritogenic alphaviruses, such as Chikungunya virus (CHIKV), cause severe and debilitating rheumatic diseases worldwide, resulting in severe morbidity and economic costs. Recently, MXRA8 was reported as an entry receptor. Here, we present the crystal structures of the mouse MXRA8, human MXRA8 in complex with the CHIKV E protein, and the cryo-electron microscopy structure of human MXRA8 and CHIKV virus-like particle. MXRA8 has two Ig-like domains with unique structural topologies. This receptor binds in the "canyon" between two protomers of the E spike on the surface of the virion. The atomic details at the interface between the two binding entities reveal that both the two domains and the hinge region of MXRA8 are involved in interaction with CHIKV E1-E2 residues from two protomers. Notably, the stalk region of MXRA8 is critical for CHIKV virus entry. This finding provides important information regarding the development of therapeutic countermeasures against those arthritogenic alphaviruses.
Asunto(s)
Virus Chikungunya/química , Proteínas de la Membrana/química , Proteínas del Envoltorio Viral/química , Internalización del Virus , Animales , Virus Chikungunya/metabolismo , Chlorocebus aethiops , Células HEK293 , Humanos , Proteínas de la Membrana/metabolismo , Dominios Proteicos , Células Vero , Proteínas del Envoltorio Viral/metabolismoRESUMEN
A hallmark feature of inflammation is the orchestrated recruitment of neutrophils from the bloodstream into inflamed tissue. Although selectins and integrins mediate recruitment in many tissues, they have a minimal role in the lungs and liver. Exploiting an unbiased in vivo functional screen, we identified a lung and liver homing peptide that functionally abrogates neutrophil recruitment to these organs. Using biochemical, genetic, and confocal intravital imaging approaches, we identified dipeptidase-1 (DPEP1) as the target and established its role as a physical adhesion receptor for neutrophil sequestration independent of its enzymatic activity. Importantly, genetic ablation or functional peptide blocking of DPEP1 significantly reduced neutrophil recruitment to the lungs and liver and provided improved survival in models of endotoxemia. Our data establish DPEP1 as a major adhesion receptor on the lung and liver endothelium and identify a therapeutic target for neutrophil-driven inflammatory diseases of the lungs.
Asunto(s)
Dipeptidasas/metabolismo , Neutrófilos/fisiología , Complejo GPIb-IX de Glicoproteína Plaquetaria/metabolismo , Animales , Cilastatina/farmacología , Cilastatina/uso terapéutico , Dipeptidasas/antagonistas & inhibidores , Dipeptidasas/genética , Modelos Animales de Enfermedad , Endotoxemia/mortalidad , Endotoxemia/patología , Endotoxemia/prevención & control , Proteínas Ligadas a GPI/antagonistas & inhibidores , Proteínas Ligadas a GPI/genética , Proteínas Ligadas a GPI/metabolismo , Humanos , Lipopolisacáridos/farmacología , Hígado/efectos de los fármacos , Hígado/inmunología , Hígado/metabolismo , Pulmón/efectos de los fármacos , Pulmón/inmunología , Pulmón/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones SCID , Infiltración Neutrófila/efectos de los fármacos , Péptidos/síntesis química , Péptidos/química , Péptidos/farmacología , Tasa de SupervivenciaRESUMEN
Tight junctions are cell-adhesion complexes that seal tissues and are involved in cell polarity and signaling. Supra-molecular assembly and positioning of tight junctions as continuous networks of adhesion strands are dependent on the membrane-associated scaffolding proteins ZO1 and ZO2. To understand how zona occludens (ZO) proteins organize junction assembly, we performed quantitative cell biology and in vitro reconstitution experiments. We discovered that ZO proteins self-organize membrane-attached compartments via phase separation. We identified the multivalent interactions of the conserved PDZ-SH3-GuK supra-domain as the driver of phase separation. These interactions are regulated by phosphorylation and intra-molecular binding. Formation of condensed ZO protein compartments is sufficient to specifically enrich and localize tight-junction proteins, including adhesion receptors, cytoskeletal adapters, and transcription factors. Our results suggest that an active-phase transition of ZO proteins into a condensed membrane-bound compartment drives claudin polymerization and coalescence of a continuous tight-junction belt.
Asunto(s)
Uniones Estrechas/genética , Proteínas de la Zonula Occludens/genética , Proteína de la Zonula Occludens-1/genética , Proteína de la Zonula Occludens-2/genética , Animales , Sitios de Unión/genética , Adhesión Celular/genética , Polaridad Celular/genética , Perros , Células HEK293 , Humanos , Células de Riñón Canino Madin Darby , Proteínas de la Membrana/genética , Dominios PDZ/genética , Fosfoproteínas/genética , Fosforilación/genética , Unión Proteica/genética , Transducción de Señal/genética , Uniones Estrechas/metabolismo , Proteínas de la Zonula Occludens/química , Proteínas de la Zonula Occludens/ultraestructura , Proteína de la Zonula Occludens-1/química , Proteína de la Zonula Occludens-1/ultraestructura , Proteína de la Zonula Occludens-2/química , Proteína de la Zonula Occludens-2/ultraestructura , Dominios Homologos src/genéticaRESUMEN
Focal adhesions (FAs) are protein machineries essential for cell adhesion, migration, and differentiation. Talin is an integrin-activating and tension-sensing FA component directly connecting integrins in the plasma membrane with the actomyosin cytoskeleton. To understand how talin function is regulated, we determined a cryoelectron microscopy (cryo-EM) structure of full-length talin1 revealing a two-way mode of autoinhibition. The actin-binding rod domains fold into a 15-nm globular arrangement that is interlocked by the integrin-binding FERM head. In turn, the rod domains R9 and R12 shield access of the FERM domain to integrin and the phospholipid PIP2 at the membrane. This mechanism likely ensures synchronous inhibition of integrin, membrane, and cytoskeleton binding. We also demonstrate that compacted talin1 reversibly unfolds to an â¼60-nm string-like conformation, revealing interaction sites for vinculin and actin. Our data explain how fast switching between active and inactive conformations of talin could regulate FA turnover, a process critical for cell adhesion and signaling.
Asunto(s)
Adhesiones Focales/metabolismo , Dominios y Motivos de Interacción de Proteínas , Talina/química , Talina/metabolismo , Actinas/metabolismo , Actomiosina/metabolismo , Sitios de Unión , Adhesión Celular/fisiología , Microscopía por Crioelectrón , Citoesqueleto/metabolismo , Dimerización , Escherichia coli/metabolismo , Humanos , Integrinas/metabolismo , Modelos Moleculares , Unión Proteica , Transducción de Señal/fisiología , Vinculina/metabolismoRESUMEN
Tumors weakly infiltrated by T lymphocytes poorly respond to immunotherapy. We aimed to unveil malignancy-associated programs regulating T cell entrance, arrest, and activation in the tumor environment. Differential expression of cell adhesion and tissue architecture programs, particularly the presence of the membrane tetraspanin claudin (CLDN)18 as a signature gene, demarcated immune-infiltrated from immune-depleted mouse pancreatic tumors. In human pancreatic ductal adenocarcinoma (PDAC) and non-small cell lung cancer, CLDN18 expression positively correlated with more differentiated histology and favorable prognosis. CLDN18 on the cell surface promoted accrual of cytotoxic T lymphocytes (CTLs), facilitating direct CTL contacts with tumor cells by driving the mobilization of the adhesion protein ALCAM to the lipid rafts of the tumor cell membrane through actin. This process favored the formation of robust immunological synapses (ISs) between CTLs and CLDN18-positive cancer cells, resulting in increased T cell activation. Our data reveal an immune role for CLDN18 in orchestrating T cell infiltration and shaping the tumor immune contexture.
Asunto(s)
Carcinoma Ductal Pancreático , Claudinas , Activación de Linfocitos , Neoplasias Pancreáticas , Linfocitos T Citotóxicos , Animales , Humanos , Ratones , Carcinoma de Pulmón de Células no Pequeñas/inmunología , Carcinoma de Pulmón de Células no Pequeñas/patología , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Carcinoma Ductal Pancreático/inmunología , Carcinoma Ductal Pancreático/patología , Carcinoma Ductal Pancreático/metabolismo , Línea Celular Tumoral , Claudinas/metabolismo , Claudinas/genética , Regulación Neoplásica de la Expresión Génica/inmunología , Sinapsis Inmunológicas/metabolismo , Sinapsis Inmunológicas/inmunología , Neoplasias Pulmonares/inmunología , Neoplasias Pulmonares/patología , Activación de Linfocitos/inmunología , Linfocitos Infiltrantes de Tumor/inmunología , Microdominios de Membrana/metabolismo , Microdominios de Membrana/inmunología , Ratones Endogámicos C57BL , Neoplasias Pancreáticas/inmunología , Neoplasias Pancreáticas/patología , Linfocitos T Citotóxicos/inmunología , Microambiente Tumoral/inmunologíaRESUMEN
Teneurins (TENs) are cell-surface adhesion proteins with critical roles in tissue development and axon guidance. Here, we report the 3.1-Å cryoelectron microscopy structure of the human TEN2 extracellular region (ECR), revealing a striking similarity to bacterial Tc-toxins. The ECR includes a large ß barrel that partially encapsulates a C-terminal domain, which emerges to the solvent through an opening in the mid-barrel region. An immunoglobulin (Ig)-like domain seals the bottom of the barrel while a ß propeller is attached in a perpendicular orientation. We further show that an alternatively spliced region within the ß propeller acts as a switch to regulate trans-cellular adhesion of TEN2 to latrophilin (LPHN), a transmembrane receptor known to mediate critical functions in the central nervous system. One splice variant activates trans-cellular signaling in a LPHN-dependent manner, whereas the other induces inhibitory postsynaptic differentiation. These results highlight the unusual structural organization of TENs giving rise to their multifarious functions.