RESUMEN
Polarized cells rely on a polarized cytoskeleton to function. Yet, how cortical polarity cues induce cytoskeleton polarization remains elusive. Here, we capitalized on recently established designed 2D protein arrays to ectopically engineer cortical polarity of virtually any protein of interest during mitosis in various cell types. This enables direct manipulation of polarity signaling and the identification of the cortical cues sufficient for cytoskeleton polarization. Using this assay, we dissected the logic of the Par complex pathway, a key regulator of cytoskeleton polarity during asymmetric cell division. We show that cortical clustering of any Par complex subunit is sufficient to trigger complex assembly and that the primary kinetic barrier to complex assembly is the relief of Par6 autoinhibition. Further, we found that inducing cortical Par complex polarity induces two hallmarks of asymmetric cell division in unpolarized mammalian cells: spindle orientation, occurring via Par3, and central spindle asymmetry, depending on aPKC activity.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales , Polaridad Celular , Técnicas Citológicas , Mitosis , Animales , Citoesqueleto/metabolismo , Mamíferos/metabolismo , Microtúbulos/metabolismo , Proteína Quinasa C/metabolismo , Proteínas Adaptadoras Transductoras de Señales/metabolismoRESUMEN
Immune-microbe interactions early in life influence the risk of allergies, asthma, and other inflammatory diseases. Breastfeeding guides healthier immune-microbe relationships by providing nutrients to specialized microbes that in turn benefit the host's immune system. Such bacteria have co-evolved with humans but are now increasingly rare in modern societies. Here we show that a lack of bifidobacteria, and in particular depletion of genes required for human milk oligosaccharide (HMO) utilization from the metagenome, is associated with systemic inflammation and immune dysregulation early in life. In breastfed infants given Bifidobacterium infantis EVC001, which expresses all HMO-utilization genes, intestinal T helper 2 (Th2) and Th17 cytokines were silenced and interferon ß (IFNß) was induced. Fecal water from EVC001-supplemented infants contains abundant indolelactate and B. infantis-derived indole-3-lactic acid (ILA) upregulated immunoregulatory galectin-1 in Th2 and Th17 cells during polarization, providing a functional link between beneficial microbes and immunoregulation during the first months of life.
Asunto(s)
Bifidobacterium/fisiología , Sistema Inmunológico/crecimiento & desarrollo , Sistema Inmunológico/microbiología , Antibacterianos/farmacología , Biomarcadores/metabolismo , Lactancia Materna , Linfocitos T CD4-Positivos/inmunología , Polaridad Celular , Proliferación Celular , Citocinas/metabolismo , Heces/química , Heces/microbiología , Galectina 1/metabolismo , Microbioma Gastrointestinal , Humanos , Indoles/metabolismo , Recién Nacido , Inflamación/sangre , Inflamación/genética , Mucosa Intestinal/inmunología , Metaboloma , Leche Humana/química , Oligosacáridos/metabolismo , Células Th17/inmunología , Células Th2/inmunología , AguaRESUMEN
Polyamine synthesis represents one of the most profound metabolic changes during T cell activation, but the biological implications of this are scarcely known. Here, we show that polyamine metabolism is a fundamental process governing the ability of CD4+ helper T cells (TH) to polarize into different functional fates. Deficiency in ornithine decarboxylase, a crucial enzyme for polyamine synthesis, results in a severe failure of CD4+ T cells to adopt correct subset specification, underscored by ectopic expression of multiple cytokines and lineage-defining transcription factors across TH cell subsets. Polyamines control TH differentiation by providing substrates for deoxyhypusine synthase, which synthesizes the amino acid hypusine, and mice in which T cells are deficient for hypusine develop severe intestinal inflammatory disease. Polyamine-hypusine deficiency caused widespread epigenetic remodeling driven by alterations in histone acetylation and a re-wired tricarboxylic acid (TCA) cycle. Thus, polyamine metabolism is critical for maintaining the epigenome to focus TH cell subset fidelity.
Asunto(s)
Linaje de la Célula , Poliaminas/metabolismo , Linfocitos T Colaboradores-Inductores/citología , Linfocitos T Colaboradores-Inductores/metabolismo , Animales , Diferenciación Celular/efectos de los fármacos , Linaje de la Célula/efectos de los fármacos , Polaridad Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Cromatina/metabolismo , Ciclo del Ácido Cítrico/efectos de los fármacos , Colitis/inmunología , Colitis/patología , Citocinas/metabolismo , Modelos Animales de Enfermedad , Inhibidores Enzimáticos/farmacología , Epigenoma , Histonas/metabolismo , Inflamación/inmunología , Inflamación/patología , Subgrupos Linfocitarios/efectos de los fármacos , Subgrupos Linfocitarios/metabolismo , Lisina/análogos & derivados , Lisina/metabolismo , Ratones , Ratones Endogámicos C57BL , Ornitina Descarboxilasa/metabolismo , Linfocitos T Colaboradores-Inductores/efectos de los fármacos , Células Th17/efectos de los fármacos , Células Th17/inmunología , Factores de Transcripción/metabolismoRESUMEN
A mysterious feature of Crohn's disease (CD) is the extra-intestinal manifestation of "creeping fat" (CrF), defined as expansion of mesenteric adipose tissue around the inflamed and fibrotic intestine. In the current study, we explore whether microbial translocation in CD serves as a central cue for CrF development. We discovered a subset of mucosal-associated gut bacteria that consistently translocated and remained viable in CrF in CD ileal surgical resections, and identified Clostridium innocuum as a signature of this consortium with strain variation between mucosal and adipose isolates, suggesting preference for lipid-rich environments. Single-cell RNA sequencing characterized CrF as both pro-fibrotic and pro-adipogenic with a rich milieu of activated immune cells responding to microbial stimuli, which we confirm in gnotobiotic mice colonized with C. innocuum. Ex vivo validation of expression patterns suggests C. innocuum stimulates tissue remodeling via M2 macrophages, leading to an adipose tissue barrier that serves to prevent systemic dissemination of bacteria.
Asunto(s)
Tejido Adiposo/microbiología , Traslocación Bacteriana , Microbioma Gastrointestinal , Mesenterio/microbiología , Tejido Adiposo/patología , Animales , Biodiversidad , Biomarcadores/metabolismo , Polaridad Celular , Células Cultivadas , Colitis Ulcerosa/patología , Enfermedad de Crohn/microbiología , Enfermedad de Crohn/patología , Microbioma Gastrointestinal/genética , Regulación de la Expresión Génica , Vida Libre de Gérmenes , Humanos , Íleon/microbiología , Íleon/patología , Lipopolisacáridos/metabolismo , Macrófagos/metabolismo , Metagenoma , Metagenómica , Ratones , Ratones Endogámicos C57BL , Fenotipo , ARN Ribosómico 16S/genética , Células Madre/metabolismoRESUMEN
Cell polarity is fundamental for tissue morphogenesis in multicellular organisms. Plants and animals evolved multicellularity independently, and it is unknown whether their polarity systems are derived from a single-celled ancestor. Planar polarity in animals is conferred by Wnt signaling, an ancient signaling pathway transduced by Dishevelled, which assembles signalosomes by dynamic head-to-tail DIX domain polymerization. In contrast, polarity-determining pathways in plants are elusive. We recently discovered Arabidopsis SOSEKI proteins, which exhibit polar localization throughout development. Here, we identify SOSEKI as ancient polar proteins across land plants. Concentration-dependent polymerization via a bona fide DIX domain allows these to recruit ANGUSTIFOLIA to polar sites, similar to the polymerization-dependent recruitment of signaling effectors by Dishevelled. Cross-kingdom domain swaps reveal functional equivalence of animal and plant DIX domains. We trace DIX domains to unicellular eukaryotes and thus show that DIX-dependent polymerization is an ancient mechanism conserved between kingdoms and central to polarity proteins.
Asunto(s)
Arabidopsis/química , Arabidopsis/citología , Polaridad Celular/fisiología , Células Vegetales/fisiología , Polimerizacion , Dominios Proteicos , Animales , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Proteína Axina/química , Proteína Axina/metabolismo , Bryopsida/química , Bryopsida/citología , Bryopsida/genética , Bryopsida/crecimiento & desarrollo , Células COS , Chlorocebus aethiops , Proteínas Dishevelled/metabolismo , Células HEK293 , Humanos , Marchantia/química , Marchantia/citología , Marchantia/genética , Marchantia/crecimiento & desarrollo , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Plantas Modificadas Genéticamente , Proteínas Represoras/metabolismo , Vía de Señalización WntRESUMEN
Epithelial cells are the most common cell type in all animals, forming the sheets and tubes that compose most organs and tissues. Apical-basal polarity is essential for epithelial cell form and function, as it determines the localization of the adhesion molecules that hold the cells together laterally and the occluding junctions that act as barriers to paracellular diffusion. Polarity must also target the secretion of specific cargoes to the apical, lateral or basal membranes and organize the cytoskeleton and internal architecture of the cell. Apical-basal polarity in many cells is established by conserved polarity factors that define the apical (Crumbs, Stardust/PALS1, aPKC, PAR-6 and CDC42), junctional (PAR-3) and lateral (Scribble, DLG, LGL, Yurt and RhoGAP19D) domains, although recent evidence indicates that not all epithelia polarize by the same mechanism. Research has begun to reveal the dynamic interactions between polarity factors and how they contribute to polarity establishment and maintenance. Elucidating these mechanisms is essential to better understand the roles of apical-basal polarity in morphogenesis and how defects in polarity contribute to diseases such as cancer.
Asunto(s)
Polaridad Celular , Proteínas de Drosophila , Animales , Polaridad Celular/fisiología , Proteínas de Drosophila/metabolismo , Células Epiteliales , Epitelio/metabolismo , MorfogénesisRESUMEN
Segregation of maternal determinants within the oocyte constitutes the first step in embryo patterning. In zebrafish oocytes, extensive ooplasmic streaming leads to the segregation of ooplasm from yolk granules along the animal-vegetal axis of the oocyte. Here, we show that this process does not rely on cortical actin reorganization, as previously thought, but instead on a cell-cycle-dependent bulk actin polymerization wave traveling from the animal to the vegetal pole of the oocyte. This wave functions in segregation by both pulling ooplasm animally and pushing yolk granules vegetally. Using biophysical experimentation and theory, we show that ooplasm pulling is mediated by bulk actin network flows exerting friction forces on the ooplasm, while yolk granule pushing is achieved by a mechanism closely resembling actin comet formation on yolk granules. Our study defines a novel role of cell-cycle-controlled bulk actin polymerization waves in oocyte polarization via ooplasmic segregation.
Asunto(s)
Actinas/metabolismo , Ciclo Celular/fisiología , Oocitos/metabolismo , Actinas/fisiología , Animales , Polaridad Celular/fisiología , Citoplasma/metabolismo , Yema de Huevo/fisiología , Polimerizacion , Pez Cebra/embriología , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismo , CigotoRESUMEN
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
Cells have the ability to respond to various types of environmental cues, and in many cases these cues induce directed cell migration towards or away from these signals. How cells sense these cues and how they transmit that information to the cytoskeletal machinery governing cell translocation is one of the oldest and most challenging problems in biology. Chemotaxis, or migration towards diffusible chemical cues, has been studied for more than a century, but information is just now beginning to emerge about how cells respond to other cues, such as substrate-associated cues during haptotaxis (chemical cues on the surface), durotaxis (mechanical substrate compliance) and topotaxis (geometric features of substrate). Here we propose four common principles, or pillars, that underlie all forms of directed migration. First, a signal must be generated, a process that in physiological environments is much more nuanced than early studies suggested. Second, the signal must be sensed, sometimes by cell surface receptors, but also in ways that are not entirely clear, such as in the case of mechanical cues. Third, the signal has to be transmitted from the sensing modules to the machinery that executes the actual movement, a step that often requires amplification. Fourth, the signal has to be converted into the application of asymmetric force relative to the substrate, which involves mostly the cytoskeleton, but perhaps other players as well. Use of these four pillars has allowed us to compare some of the similarities between different types of directed migration, but also to highlight the remarkable diversity in the mechanisms that cells use to respond to different cues provided by their environment.
Asunto(s)
Movimiento Celular/fisiología , Animales , Polaridad Celular , Quimiotaxis , Citoesqueleto/metabolismo , Humanos , Transducción de SeñalRESUMEN
Endocytosis allows cells to transport particles and molecules across the plasma membrane. In addition, it is involved in the termination of signalling through receptor downmodulation and degradation. This traditional outlook has been substantially modified in recent years by discoveries that endocytosis and subsequent trafficking routes have a profound impact on the positive regulation and propagation of signals, being key for the spatiotemporal regulation of signal transmission in cells. Accordingly, endocytosis and membrane trafficking regulate virtually every aspect of cell physiology and are frequently subverted in pathological conditions. Two key aspects of endocytic control over signalling are coming into focus: context-dependency and long-range effects. First, endocytic-regulated outputs are not stereotyped but heavily dependent on the cell-specific regulation of endocytic networks. Second, endocytic regulation has an impact not only on individual cells but also on the behaviour of cellular collectives. Herein, we will discuss recent advancements in these areas, highlighting how endocytic trafficking impacts complex cell properties, including cell polarity and collective cell migration, and the relevance of these mechanisms to disease, in particular cancer.
Asunto(s)
Membrana Celular/metabolismo , Endocitosis/fisiología , Endosomas/metabolismo , Animales , Transporte Biológico , Movimiento Celular , Polaridad Celular , Humanos , Morfogénesis , Transducción de SeñalRESUMEN
In multicellular systems, oriented cell divisions are essential for morphogenesis and homeostasis as they determine the position of daughter cells within the tissue and also, in many cases, their fate. Early studies in invertebrates led to the identification of conserved core mechanisms of mitotic spindle positioning centred on the Gαi-LGN-NuMA-dynein complex. In recent years, much has been learnt about the way this complex functions in vertebrate cells. In particular, studies addressed how the Gαi-LGN-NuMA-dynein complex dynamically crosstalks with astral microtubules and the actin cytoskeleton, and how it is regulated to orient the spindle according to cellular and tissue-wide cues. We have also begun to understand how dynein motors and actin regulators interact with mechanosensitive adhesion molecules sensing extracellular mechanical stimuli, such as cadherins and integrins, and with signalling pathways so as to respond to extracellular cues instructing the orientation of the division axis in vivo. In this Review, with the focus on epithelial tissues, we discuss the molecular mechanisms of mitotic spindle orientation in vertebrate cells, and how this machinery is regulated by epithelial cues and extracellular signals to maintain tissue cohesiveness during mitosis. We also outline recent knowledge of how spindle orientation impacts tissue architecture in epithelia and its emerging links to the regulation of cell fate decisions. Finally, we describe how defective spindle orientation can be corrected or its effects eliminated in tissues under physiological conditions, and the pathological implications associated with spindle misorientation.
Asunto(s)
Huso Acromático/metabolismo , Citoesqueleto de Actina/metabolismo , Animales , Diferenciación Celular , Polaridad Celular , Células Epiteliales/citología , Células Epiteliales/metabolismo , Epitelio/metabolismo , Humanos , Mitosis , Transducción de SeñalRESUMEN
Cell polarity in plants operates across a broad range of spatial and temporal scales to control processes from acute cell growth to systemic hormone distribution. Similar to other eukaryotes, plants generate polarity at both the subcellular and tissue levels, often through polarization of membrane-associated protein complexes. However, likely due to the constraints imposed by the cell wall and their extremely plastic development, plants possess novel polarity molecules and mechanisms highly tuned to environmental inputs. Considerable progress has been made in identifying key plant polarity regulators, but detailed molecular understanding of polarity mechanisms remains incomplete in plants. Here, we emphasize the striking similarities in the conceptual frameworks that generate polarity in both animals and plants. To this end, we highlight how novel, plant-specific proteins engage in common themes of positive feedback, dynamic intracellular trafficking, and posttranslational regulation to establish polarity axes in development. We end with a discussion of how environmental signals control intrinsic polarity to impact postembryonic organogenesis and growth.
Asunto(s)
Polaridad Celular , Células Vegetales/fisiología , Animales , División Celular , Pared Celular/química , Células Eucariotas/citología , Células Vegetales/química , Células Vegetales/enzimología , Proteínas de Plantas/metabolismo , Proteínas de Unión al GTP rho/metabolismoRESUMEN
Polarization along an apico-basolateral axis is a hallmark of epithelial cells and is essential for their selective barrier and transporter functions, as well as for their ability to provide mechanical resiliency to organs. Loss of polarity along this axis perturbs development and is associated with a wide number of diseases. We describe three steps involved in polarization: symmetry breaking, polarity establishment, and polarity maintenance. While the proteins involved in these processes are highly conserved among epithelial tissues and species, the execution of these steps varies widely and is context dependent. We review both theoretical principles underlying these steps and recent work demonstrating how apico-basolateral polarity is established in vivo in different tissues, highlighting how developmental and physiological contexts play major roles in the execution of the epithelial polarity program.
Asunto(s)
Membrana Basal/metabolismo , Polaridad Celular , Células Epiteliales/citología , Epitelio/metabolismo , Animales , Membrana Basal/citología , Comunicación Celular , Matriz Extracelular/metabolismo , Humanos , Proteínas de la Membrana/metabolismo , Transducción de SeñalRESUMEN
Microtubules are core components of the cytoskeleton and serve as tracks for motor protein-based intracellular transport. Microtubule networks are highly diverse across different cell types and are believed to adapt to cell type-specific transport demands. Here we review how the spatial organization of different subsets of microtubules into higher-order networks determines the traffic rules for motor-based transport in different animal cell types. We describe the interplay between microtubule network organization and motor-based transport within epithelial cells, oocytes, neurons, cilia, and the spindle apparatus.
Asunto(s)
Microtúbulos/metabolismo , Animales , Polaridad Celular , Citoesqueleto/química , Citoesqueleto/metabolismo , Humanos , Proteínas Asociadas a Microtúbulos/metabolismo , Microtúbulos/química , Proteínas Motoras Moleculares/metabolismo , Transporte de Proteínas , Huso Acromático/química , Huso Acromático/metabolismoRESUMEN
Blood platelets are critical for hemostasis and thrombosis and play diverse roles during immune responses. Despite these versatile tasks in mammalian biology, their skills on a cellular level are deemed limited, mainly consisting in rolling, adhesion, and aggregate formation. Here, we identify an unappreciated asset of platelets and show that adherent platelets use adhesion receptors to mechanically probe the adhesive substrate in their local microenvironment. When actomyosin-dependent traction forces overcome substrate resistance, platelets migrate and pile up the adhesive substrate together with any bound particulate material. They use this ability to act as cellular scavengers, scanning the vascular surface for potential invaders and collecting deposited bacteria. Microbe collection by migrating platelets boosts the activity of professional phagocytes, exacerbating inflammatory tissue injury in sepsis. This assigns platelets a central role in innate immune responses and identifies them as potential targets to dampen inflammatory tissue damage in clinical scenarios of severe systemic infection.
Asunto(s)
Infecciones Bacterianas/inmunología , Plaquetas/inmunología , Animales , Bacterias/clasificación , Plaquetas/citología , Vasos Sanguíneos/lesiones , Vasos Sanguíneos/patología , Calcio/metabolismo , Movimiento Celular , Polaridad Celular , Humanos , Inflamación/inmunología , Integrinas/metabolismo , Ratones , Miosinas/metabolismo , Neutrófilos/citologíaRESUMEN
P granules are non-membrane-bound RNA-protein compartments that are involved in germline development in C. elegans. They are liquids that condense at one end of the embryo by localized phase separation, driven by gradients of polarity proteins such as the mRNA-binding protein MEX-5. To probe how polarity proteins regulate phase separation, we combined biochemistry and theoretical modeling. We reconstitute P granule-like droplets in vitro using a single protein PGL-3. By combining in vitro reconstitution with measurements of intracellular concentrations, we show that competition between PGL-3 and MEX-5 for mRNA can regulate the formation of PGL-3 droplets. Using theory, we show that, in a MEX-5 gradient, this mRNA competition mechanism can drive a gradient of P granule assembly with similar spatial and temporal characteristics to P granule assembly in vivo. We conclude that gradients of polarity proteins can position RNP granules during development by using RNA competition to regulate local phase separation.
Asunto(s)
Caenorhabditis elegans/metabolismo , ARN Mensajero/metabolismo , Animales , Proteínas de Caenorhabditis elegans/análisis , Proteínas de Caenorhabditis elegans/metabolismo , Polaridad Celular , Embrión no Mamífero , Espacio Intracelular/química , Espacio Intracelular/metabolismo , Modelos Teóricos , Unión Proteica , Proteínas de Unión al ARN/análisis , Proteínas de Unión al ARN/metabolismoRESUMEN
Cell polarization is crucial for the functioning of all organisms. The cytoskeleton is central to the process but its role in symmetry breaking is poorly understood. We study cell polarization when fission yeast cells exit starvation. We show that the basis of polarity generation is de novo sterol biosynthesis, cell surface delivery of sterols, and their recruitment to the cell poles. This involves four phases occurring independent of the polarity factor cdc42p. Initially, multiple, randomly distributed sterol-rich membrane (SRM) domains form at the plasma membrane, independent of the cytoskeleton and cell growth. These domains provide platforms on which the growth and polarity machinery assembles. SRM domains are then polarized by the microtubule-dependent polarity factor tea1p, which prepares for monopolar growth initiation and later switching to bipolar growth. SRM polarization requires F-actin but not the F-actin organizing polarity factors for3p and bud6p. We conclude that SRMs are key to cell polarization.
Asunto(s)
Membrana Celular/química , Schizosaccharomyces/química , Schizosaccharomyces/citología , Actinas/metabolismo , Polaridad Celular , Citoesqueleto/metabolismo , Microdominios de Membrana , Proteínas Asociadas a Microtúbulos/metabolismo , Schizosaccharomyces/crecimiento & desarrollo , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Proteína de Unión al GTP cdc42/metabolismoRESUMEN
A conserved molecular machinery centered on the Cdc42 GTPase regulates cell polarity in diverse organisms. Here we review findings from budding and fission yeasts that reveal both a conserved core polarity circuit and several adaptations that each organism exploits to fulfill the needs of its lifestyle. The core circuit involves positive feedback by local activation of Cdc42 to generate a cluster of concentrated GTP-Cdc42 at the membrane. Species-specific pathways regulate the timing of polarization during the cell cycle, as well as the location and number of polarity sites.