RESUMEN
Cellular homeostasis is intricately influenced by stimuli from the microenvironment, including signaling molecules, metabolites, and pathogens. Functioning as a signaling hub within the cell, mitochondria integrate information from various intracellular compartments to regulate cellular signaling and metabolism. Multiple studies have shown that mitochondria may respond to various extracellular signaling events. However, it is less clear how changes in the extracellular matrix (ECM) can impact mitochondrial homeostasis to regulate animal physiology. We find that ECM remodeling alters mitochondrial homeostasis in an evolutionarily conserved manner. Mechanistically, ECM remodeling triggers a TGF-ß response to induce mitochondrial fission and the unfolded protein response of the mitochondria (UPRMT). At the organismal level, ECM remodeling promotes defense of animals against pathogens through enhanced mitochondrial stress responses. We postulate that this ECM-mitochondria crosstalk represents an ancient immune pathway, which detects infection- or mechanical-stress-induced ECM damage, thereby initiating adaptive mitochondria-based immune and metabolic responses.
Asunto(s)
Matriz Extracelular , Homeostasis , Mitocondrias , Respuesta de Proteína Desplegada , Matriz Extracelular/metabolismo , Animales , Mitocondrias/metabolismo , Humanos , Factor de Crecimiento Transformador beta/metabolismo , Dinámicas Mitocondriales , Ratones , Transducción de Señal , Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/inmunologíaRESUMEN
Human brain development involves an orchestrated, massive neural progenitor expansion while a multi-cellular tissue architecture is established. Continuously expanding organoids can be grown directly from multiple somatic tissues, yet to date, brain organoids can solely be established from pluripotent stem cells. Here, we show that healthy human fetal brain in vitro self-organizes into organoids (FeBOs), phenocopying aspects of in vivo cellular heterogeneity and complex organization. FeBOs can be expanded over long time periods. FeBO growth requires maintenance of tissue integrity, which ensures production of a tissue-like extracellular matrix (ECM) niche, ultimately endowing FeBO expansion. FeBO lines derived from different areas of the central nervous system (CNS), including dorsal and ventral forebrain, preserve their regional identity and allow to probe aspects of positional identity. Using CRISPR-Cas9, we showcase the generation of syngeneic mutant FeBO lines for the study of brain cancer. Taken together, FeBOs constitute a complementary CNS organoid platform.
Asunto(s)
Encéfalo , Organoides , Humanos , Encéfalo/citología , Encéfalo/crecimiento & desarrollo , Encéfalo/metabolismo , Sistema Nervioso Central/metabolismo , Matriz Extracelular/metabolismo , Células Madre Pluripotentes/metabolismo , Prosencéfalo/citología , Técnicas de Cultivo de Tejidos , Células Madre/metabolismo , MorfogénesisRESUMEN
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
Alterations in extracellular matrix (ECM) architecture and stiffness represent hallmarks of cancer. Whether the biomechanical property of ECM impacts the functionality of tumor-reactive CD8+ T cells remains largely unknown. Here, we reveal that the transcription factor (TF) Osr2 integrates biomechanical signaling and facilitates the terminal exhaustion of tumor-reactive CD8+ T cells. Osr2 expression is selectively induced in the terminally exhausted tumor-specific CD8+ T cell subset by coupled T cell receptor (TCR) signaling and biomechanical stress mediated by the Piezo1/calcium/CREB axis. Consistently, depletion of Osr2 alleviates the exhaustion of tumor-specific CD8+ T cells or CAR-T cells, whereas forced Osr2 expression aggravates their exhaustion in solid tumor models. Mechanistically, Osr2 recruits HDAC3 to rewire the epigenetic program for suppressing cytotoxic gene expression and promoting CD8+ T cell exhaustion. Thus, our results unravel Osr2 functions as a biomechanical checkpoint to exacerbate CD8+ T cell exhaustion and could be targeted to potentiate cancer immunotherapy.
Asunto(s)
Linfocitos T CD8-positivos , Factores de Transcripción , Animales , Femenino , Humanos , Ratones , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Línea Celular Tumoral , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Matriz Extracelular/metabolismo , Histona Desacetilasas/metabolismo , Ratones Endogámicos C57BL , Neoplasias/inmunología , Neoplasias/metabolismo , Receptores de Antígenos de Linfocitos T/metabolismo , Transducción de Señal , Agotamiento de Células T , Factores de Transcripción/metabolismo , Microambiente Tumoral , Estrés MecánicoRESUMEN
Ductal carcinoma in situ (DCIS) is a pre-invasive lesion that is thought to be a precursor to invasive breast cancer (IBC). To understand the changes in the tumor microenvironment (TME) accompanying transition to IBC, we used multiplexed ion beam imaging by time of flight (MIBI-TOF) and a 37-plex antibody staining panel to interrogate 79 clinically annotated surgical resections using machine learning tools for cell segmentation, pixel-based clustering, and object morphometrics. Comparison of normal breast with patient-matched DCIS and IBC revealed coordinated transitions between four TME states that were delineated based on the location and function of myoepithelium, fibroblasts, and immune cells. Surprisingly, myoepithelial disruption was more advanced in DCIS patients that did not develop IBC, suggesting this process could be protective against recurrence. Taken together, this HTAN Breast PreCancer Atlas study offers insight into drivers of IBC relapse and emphasizes the importance of the TME in regulating these processes.
Asunto(s)
Neoplasias de la Mama/patología , Carcinoma Intraductal no Infiltrante/patología , Diferenciación Celular , Estudios de Cohortes , Progresión de la Enfermedad , Células Epiteliales/patología , Epitelio/patología , Matriz Extracelular/metabolismo , Femenino , Fibroblastos/metabolismo , Fibroblastos/patología , Humanos , Persona de Mediana Edad , Invasividad Neoplásica , Recurrencia Local de Neoplasia/patología , Fenotipo , Análisis de la Célula Individual , Células del Estroma/patología , Microambiente TumoralRESUMEN
The term 'fibroblast' often serves as a catch-all for a diverse array of mesenchymal cells, including perivascular cells, stromal progenitor cells and bona fide fibroblasts. Although phenotypically similar, these subpopulations are functionally distinct, maintaining tissue integrity and serving as local progenitor reservoirs. In response to tissue injury, these cells undergo a dynamic fibroblast-myofibroblast transition, marked by extracellular matrix secretion and contraction of actomyosin-based stress fibres. Importantly, whereas transient activation into myofibroblasts aids in tissue repair, persistent activation triggers pathological fibrosis. In this Review, we discuss the roles of mechanical cues, such as tissue stiffness and strain, alongside cell signalling pathways and extracellular matrix ligands in modulating myofibroblast activation and survival. We also highlight the role of epigenetic modifications and myofibroblast memory in physiological and pathological processes. Finally, we discuss potential strategies for therapeutically interfering with these factors and the associated signal transduction pathways to improve the outcome of dysregulated healing.
Asunto(s)
Fibrosis , Miofibroblastos , Cicatrización de Heridas , Humanos , Miofibroblastos/metabolismo , Miofibroblastos/patología , Animales , Fibrosis/metabolismo , Cicatrización de Heridas/fisiología , Transducción de Señal , Matriz Extracelular/metabolismo , Fibroblastos/metabolismo , Fibroblastos/patología , Epigénesis GenéticaRESUMEN
Biofilms are community architectures adopted by bacteria inclusive of a self-formed extracellular matrix that protects resident bacteria from diverse environmental stresses and, in many species, incorporates extracellular DNA (eDNA) and DNABII proteins for structural integrity throughout biofilm development. Here, we present evidence that this eDNA-based architecture relies on the rare Z-form. Z-form DNA accumulates as biofilms mature and, through stabilization by the DNABII proteins, confers structural integrity to the biofilm matrix. Indeed, substances known to drive B-DNA into Z-DNA promoted biofilm formation whereas those that drive Z-DNA into B-DNA disrupted extant biofilms. Importantly, we demonstrated that the universal bacterial DNABII family of proteins stabilizes both bacterial- and host-eDNA in the Z-form in situ. A model is proposed that incorporates the role of Z-DNA in biofilm pathogenesis, innate immune response, and immune evasion.
Asunto(s)
Bacterias/genética , Biopelículas , ADN Bacteriano/química , Matriz Extracelular/metabolismo , Espacio Extracelular/química , Animales , Especificidad de Anticuerpos , Proteínas Bacterianas/metabolismo , Línea Celular , Chinchilla , ADN Cruciforme , Desoxirribonucleasas/metabolismo , Trampas Extracelulares/metabolismo , Humanos , Acetato de Tetradecanoilforbol/farmacologíaRESUMEN
How tissues acquire complex shapes is a fundamental question in biology and regenerative medicine. Zebrafish semicircular canals form from invaginations in the otic epithelium (buds) that extend and fuse to form the hubs of each canal. We find that conventional actomyosin-driven behaviors are not required. Instead, local secretion of hyaluronan, made by the enzymes uridine 5'-diphosphate dehydrogenase (ugdh) and hyaluronan synthase 3 (has3), drives canal morphogenesis. Charged hyaluronate polymers osmotically swell with water and generate isotropic extracellular pressure to deform the overlying epithelium into buds. The mechanical anisotropy needed to shape buds into tubes is conferred by a polarized distribution of actomyosin and E-cadherin-rich membrane tethers, which we term cytocinches. Most work on tissue morphogenesis ascribes actomyosin contractility as the driving force, while the extracellular matrix shapes tissues through differential stiffness. Our work inverts this expectation. Hyaluronate pressure shaped by anisotropic tissue stiffness may be a widespread mechanism for powering morphological change in organogenesis and tissue engineering.
Asunto(s)
Espacio Extracelular/química , Ácido Hialurónico/farmacología , Morfogénesis , Especificidad de Órganos , Presión , Canales Semicirculares/citología , Canales Semicirculares/embriología , Actomiosina/metabolismo , Animales , Anisotropía , Conducta Animal , Matriz Extracelular/metabolismo , Ácido Hialurónico/biosíntesis , Modelos Biológicos , Morfogénesis/efectos de los fármacos , Especificidad de Órganos/efectos de los fármacos , Presión Osmótica , Canales Semicirculares/diagnóstico por imagen , Conducta Estereotipada , Pez Cebra/embriología , Proteínas de Pez Cebra/metabolismoRESUMEN
Intratumoral heterogeneity is a critical frontier in understanding how the tumor microenvironment (TME) propels malignant progression. Here, we deconvolute the human pancreatic TME through large-scale integration of histology-guided regional multiOMICs with clinical data and patient-derived preclinical models. We discover "subTMEs," histologically definable tissue states anchored in fibroblast plasticity, with regional relationships to tumor immunity, subtypes, differentiation, and treatment response. "Reactive" subTMEs rich in complex but functionally coordinated fibroblast communities were immune hot and inhabited by aggressive tumor cell phenotypes. The matrix-rich "deserted" subTMEs harbored fewer activated fibroblasts and tumor-suppressive features yet were markedly chemoprotective and enriched upon chemotherapy. SubTMEs originated in fibroblast differentiation trajectories, and transitory states were notable both in single-cell transcriptomics and in situ. The intratumoral co-occurrence of subTMEs produced patient-specific phenotypic and computationally predictable heterogeneity tightly linked to malignant biology. Therefore, heterogeneity within the plentiful, notorious pancreatic TME is not random but marks fundamental tissue organizational units.
Asunto(s)
Neoplasias Pancreáticas/patología , Microambiente Tumoral , Adenocarcinoma/genética , Adenocarcinoma/inmunología , Adenocarcinoma/patología , Fibroblastos Asociados al Cáncer/patología , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/inmunología , Carcinoma Ductal Pancreático/patología , Diferenciación Celular , Proliferación Celular , Epitelio/patología , Matriz Extracelular/metabolismo , Femenino , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/inmunología , Fenotipo , Células del Estroma/patología , Análisis de Supervivencia , Microambiente Tumoral/inmunologíaRESUMEN
Fibrosis, defined by the excess deposition of structural and matricellular proteins in the extracellular space, underlies tissue dysfunction in multiple chronic diseases. Approved antifibrotics have proven modest in efficacy, and the immune compartment remains, for the most part, an untapped therapeutic opportunity. Recent single-cell analyses have interrogated human fibrotic tissues, including immune cells. These studies have revealed a conserved profile of scar-associated macrophages, which localize to the fibrotic niche and interact with mesenchymal cells that produce pathological extracellular matrix. Here we review recent advances in the understanding of the fibrotic microenvironment in human diseases, with a focus on immune cell profiles and functional immune-stromal interactions. We also discuss the key role of the immune system in mediating fibrosis regression and highlight avenues for future study to elucidate potential approaches to targeting inflammatory cells in fibrotic disorders.
Asunto(s)
Matriz Extracelular , Humanos , Fibrosis , Matriz Extracelular/metabolismoRESUMEN
Interferon-γ (IFNγ) is an important mediator of cellular immune responses, but high systemic levels of this cytokine are associated with immunopathology. IFNγ binds to its receptor (IFNγR) and to extracellular matrix (ECM) via four positively charged C-terminal amino acids (KRKR), the ECM-binding domain (EBD). Across evolution, IFNγ is not well conserved, but the EBD is highly conserved, suggesting a critical function. Here, we show that IFNγ lacking the EBD (IFNγΔKRKR) does not bind to ECM but still binds to the IFNγR and retains bioactivity. Overexpression of IFNγΔKRKR in tumors reduced local ECM binding, increased systemic levels and induced sickness behavior, weight loss and toxicity. To analyze the function of the EBD during infection, we generated IFNγΔKRKR mice lacking the EBD by using CRISPR-Cas9. Infection with lymphocytic choriomeningitis virus resulted in higher systemic IFNγΔKRKR levels, enhanced sickness behavior, weight loss and fatal toxicity. We conclude that local retention of IFNγ is a pivotal mechanism to protect the organism from systemic toxicity during prolonged immune stimulation.
Asunto(s)
Citocinas , Neoplasias , Ratones , Animales , Citocinas/metabolismo , Interferón gamma/metabolismo , Transducción de Señal , Matriz Extracelular/metabolismoRESUMEN
Mechanical properties of extracellular matrices (ECMs) regulate essential cell behaviours, including differentiation, migration and proliferation, through mechanotransduction. Studies of cell-ECM mechanotransduction have largely focused on cells cultured in 2D, on top of elastic substrates with a range of stiffnesses. However, cells often interact with ECMs in vivo in a 3D context, and cell-ECM interactions and mechanisms of mechanotransduction in 3D can differ from those in 2D. The ECM exhibits various structural features as well as complex mechanical properties. In 3D, mechanical confinement by the surrounding ECM restricts changes in cell volume and cell shape but allows cells to generate force on the matrix by extending protrusions and regulating cell volume as well as through actomyosin-based contractility. Furthermore, cell-matrix interactions are dynamic owing to matrix remodelling. Accordingly, ECM stiffness, viscoelasticity and degradability often play a critical role in regulating cell behaviours in 3D. Mechanisms of 3D mechanotransduction include traditional integrin-mediated pathways that sense mechanical properties and more recently described mechanosensitive ion channel-mediated pathways that sense 3D confinement, with both converging on the nucleus for downstream control of transcription and phenotype. Mechanotransduction is involved in tissues from development to cancer and is being increasingly harnessed towards mechanotherapy. Here we discuss recent progress in our understanding of cell-ECM mechanotransduction in 3D.
Asunto(s)
Matriz Extracelular , Mecanotransducción Celular , Matriz Extracelular/metabolismo , Citoesqueleto de Actina , Diferenciación Celular , Integrinas/metabolismoRESUMEN
Cell invasion into the surrounding extracellular matrix or across tissue boundaries and endothelial barriers occurs in both physiological and pathological scenarios such as immune surveillance or cancer metastasis. Podosomes and invadopodia, collectively called 'invadosomes', are actin-based structures that drive the proteolytic invasion of cells, by forming highly regulated platforms for the localized release of lytic enzymes that degrade the matrix. Recent advances in high-resolution microscopy techniques, in vivo imaging and high-throughput analyses have led to considerable progress in understanding mechanisms of invadosomes, revealing the intricate inner architecture of these structures, as well as their growing repertoire of functions that extends well beyond matrix degradation. In this Review, we discuss the known functions, architecture and regulatory mechanisms of podosomes and invadopodia. In particular, we describe the molecular mechanisms of localized actin turnover and microtubule-based cargo delivery, with a special focus on matrix-lytic enzymes that enable proteolytic invasion. Finally, we point out topics that should become important in the invadosome field in the future.
Asunto(s)
Podosomas , Podosomas/metabolismo , Actinas/metabolismo , Matriz Extracelular/metabolismo , Microtúbulos/metabolismo , ProteolisisRESUMEN
The ability of animal cells to sense, adhere to and remodel their local extracellular matrix (ECM) is central to control of cell shape, mechanical responsiveness, motility and signalling, and hence to development, tissue formation, wound healing and the immune response. Cell-ECM interactions occur at various specialized, multi-protein adhesion complexes that serve to physically link the ECM to the cytoskeleton and the intracellular signalling apparatus. This occurs predominantly via clustered transmembrane receptors of the integrin family. Here we review how the interplay of mechanical forces, biochemical signalling and molecular self-organization determines the composition, organization, mechanosensitivity and dynamics of these adhesions. Progress in the identification of core multi-protein modules within the adhesions and characterization of rearrangements of their components in response to force, together with advanced imaging approaches, has improved understanding of adhesion maturation and turnover and the relationships between adhesion structures and functions. Perturbations of adhesion contribute to a broad range of diseases and to age-related dysfunction, thus an improved understanding of their molecular nature may facilitate therapeutic intervention in these conditions.
Asunto(s)
Adhesión Celular , Citoesqueleto , Matriz Extracelular , Integrinas , Animales , Adhesión Celular/fisiología , Citoesqueleto/metabolismo , Matriz Extracelular/metabolismo , Adhesiones Focales/metabolismo , Integrinas/metabolismo , Transducción de Señal , Adherencias Tisulares/patologíaRESUMEN
Spaceflight is known to impose changes on human physiology with unknown molecular etiologies. To reveal these causes, we used a multi-omics, systems biology analytical approach using biomedical profiles from fifty-nine astronauts and data from NASA's GeneLab derived from hundreds of samples flown in space to determine transcriptomic, proteomic, metabolomic, and epigenetic responses to spaceflight. Overall pathway analyses on the multi-omics datasets showed significant enrichment for mitochondrial processes, as well as innate immunity, chronic inflammation, cell cycle, circadian rhythm, and olfactory functions. Importantly, NASA's Twin Study provided a platform to confirm several of our principal findings. Evidence of altered mitochondrial function and DNA damage was also found in the urine and blood metabolic data compiled from the astronaut cohort and NASA Twin Study data, indicating mitochondrial stress as a consistent phenotype of spaceflight.
Asunto(s)
Genómica , Mitocondrias/patología , Vuelo Espacial , Estrés Fisiológico , Animales , Ritmo Circadiano , Matriz Extracelular/metabolismo , Humanos , Inmunidad Innata , Metabolismo de los Lípidos , Análisis de Flujos Metabólicos , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Músculos/inmunología , Especificidad de Órganos , Olfato/fisiologíaRESUMEN
Synapse remodeling is essential to encode experiences into neuronal circuits. Here, we define a molecular interaction between neurons and microglia that drives experience-dependent synapse remodeling in the hippocampus. We find that the cytokine interleukin-33 (IL-33) is expressed by adult hippocampal neurons in an experience-dependent manner and defines a neuronal subset primed for synaptic plasticity. Loss of neuronal IL-33 or the microglial IL-33 receptor leads to impaired spine plasticity, reduced newborn neuron integration, and diminished precision of remote fear memories. Memory precision and neuronal IL-33 are decreased in aged mice, and IL-33 gain of function mitigates age-related decreases in spine plasticity. We find that neuronal IL-33 instructs microglial engulfment of the extracellular matrix (ECM) and that its loss leads to impaired ECM engulfment and a concomitant accumulation of ECM proteins in contact with synapses. These data define a cellular mechanism through which microglia regulate experience-dependent synapse remodeling and promote memory consolidation.
Asunto(s)
Matriz Extracelular/metabolismo , Microglía/fisiología , Plasticidad Neuronal/fisiología , Envejecimiento , Animales , Miedo , Regulación de la Expresión Génica , Hipocampo/metabolismo , Proteína 1 Similar al Receptor de Interleucina-1/genética , Proteína 1 Similar al Receptor de Interleucina-1/metabolismo , Interleucina-33/genética , Interleucina-33/metabolismo , Memoria , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Neuronas/metabolismo , Transducción de SeñalRESUMEN
Scar tissue size following myocardial infarction is an independent predictor of cardiovascular outcomes, yet little is known about factors regulating scar size. We demonstrate that collagen V, a minor constituent of heart scars, regulates the size of heart scars after ischemic injury. Depletion of collagen V led to a paradoxical increase in post-infarction scar size with worsening of heart function. A systems genetics approach across 100 in-bred strains of mice demonstrated that collagen V is a critical driver of postinjury heart function. We show that collagen V deficiency alters the mechanical properties of scar tissue, and altered reciprocal feedback between matrix and cells induces expression of mechanosensitive integrins that drive fibroblast activation and increase scar size. Cilengitide, an inhibitor of specific integrins, rescues the phenotype of increased post-injury scarring in collagen-V-deficient mice. These observations demonstrate that collagen V regulates scar size in an integrin-dependent manner.
Asunto(s)
Cicatriz/metabolismo , Colágeno Tipo V/deficiencia , Colágeno Tipo V/metabolismo , Lesiones Cardíacas/metabolismo , Contracción Miocárdica/genética , Miofibroblastos/metabolismo , Animales , Cicatriz/genética , Cicatriz/fisiopatología , Colágeno Tipo I/genética , Colágeno Tipo I/metabolismo , Cadena alfa 1 del Colágeno Tipo I , Colágeno Tipo III/genética , Colágeno Tipo III/metabolismo , Colágeno Tipo V/genética , Matriz Extracelular/genética , Matriz Extracelular/metabolismo , Femenino , Fibrosis/genética , Fibrosis/metabolismo , Regulación de la Expresión Génica/genética , Integrinas/antagonistas & inhibidores , Integrinas/genética , Integrinas/metabolismo , Isoproterenol/farmacología , Masculino , Mecanotransducción Celular/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Microscopía de Fuerza Atómica/instrumentación , Microscopía Electrónica de Transmisión , Contracción Miocárdica/efectos de los fármacos , Miofibroblastos/citología , Miofibroblastos/patología , Miofibroblastos/ultraestructura , Análisis de Componente Principal , Proteómica , RNA-Seq , Análisis de la Célula IndividualRESUMEN
Exosomes are small, single-membrane, secreted organelles of â¼30 to â¼200 nm in diameter that have the same topology as the cell and are enriched in selected proteins, lipids, nucleic acids, and glycoconjugates. Exosomes contain an array of membrane-associated, high-order oligomeric protein complexes, display pronounced molecular heterogeneity, and are created by budding at both plasma and endosome membranes. Exosome biogenesis is a mechanism of protein quality control, and once released, exosomes have activities as diverse as remodeling the extracellular matrix and transmitting signals and molecules to other cells. This pathway of intercellular vesicle traffic plays important roles in many aspects of human health and disease, including development, immunity, tissue homeostasis, cancer, and neurodegenerative diseases. In addition, viruses co-opt exosome biogenesis pathways both for assembling infectious particles and for establishing host permissiveness. On the basis of these and other properties, exosomes are being developed as therapeutic agents in multiple disease models.
Asunto(s)
Exosomas/metabolismo , Animales , Transporte Biológico , Exosomas/inmunología , Exosomas/fisiología , Exosomas/ultraestructura , Matriz Extracelular/metabolismo , Humanos , Neoplasias , Enfermedades Neurodegenerativas , Multimerización de Proteína , Transducción de SeñalRESUMEN
Emergent physical properties of tissues are not readily understood by reductionist studies of their constituent cells. Here, we show molecular signals controlling cellular, physical, and structural properties and collectively determine tissue mechanics of lymph nodes, an immunologically relevant adult tissue. Lymph nodes paradoxically maintain robust tissue architecture in homeostasis yet are continually poised for extensive expansion upon immune challenge. We find that in murine models of immune challenge, cytoskeletal mechanics of a cellular meshwork of fibroblasts determine tissue tension independently of extracellular matrix scaffolds. We determine that C-type lectin-like receptor 2 (CLEC-2)-podoplanin signaling regulates the cell surface mechanics of fibroblasts, providing a mechanically sensitive pathway to regulate lymph node remodeling. Perturbation of fibroblast mechanics through genetic deletion of podoplanin attenuates T cell activation. We find that increased tissue tension through the fibroblastic stromal meshwork is required to trigger the initiation of fibroblast proliferation and restore homeostatic cellular ratios and tissue structure through lymph node expansion.
Asunto(s)
Fibroblastos , Ganglios Linfáticos , Animales , Matriz Extracelular/metabolismo , Fibroblastos/metabolismo , Homeostasis , Lectinas Tipo C/metabolismo , RatonesRESUMEN
Cells bend their plasma membranes into highly curved forms to interact with the local environment, but how shape generation is regulated is not fully resolved. Here, we report a synergy between shape-generating processes in the cell interior and the external organization and composition of the cell-surface glycocalyx. Mucin biopolymers and long-chain polysaccharides within the glycocalyx can generate entropic forces that favor or disfavor the projection of spherical and finger-like extensions from the cell surface. A polymer brush model of the glycocalyx successfully predicts the effects of polymer size and cell-surface density on membrane morphologies. Specific glycocalyx compositions can also induce plasma membrane instabilities to generate more exotic undulating and pearled membrane structures and drive secretion of extracellular vesicles. Together, our results suggest a fundamental role for the glycocalyx in regulating curved membrane features that serve in communication between cells and with the extracellular matrix.