RESUMEN
Collective alignment of cell populations is a commonly observed phenomena in biology. An important example are aligning fibroblasts in healthy or scar tissue. In this work we derive and simulate a mechanistic agent-based model of the collective behaviour of actively moving and interacting cells, with a focus on understanding collective alignment. The derivation strategy is based on energy minimisation. The model ingredients are motivated by data on the behaviour of different populations of aligning fibroblasts and include: Self-propulsion, overlap avoidance, deformability, cell-cell junctions and cytoskeletal forces. We find that there is an optimal ratio of self-propulsion speed and overlap avoidance that maximises collective alignment. Further we find that deformability aids alignment, and that cell-cell junctions by themselves hinder alignment. However, if cytoskeletal forces are transmitted via cell-cell junctions we observe strong collective alignment over large spatial scales.
Asunto(s)
Simulación por Computador , Citoesqueleto , Uniones Intercelulares , Modelos Biológicos , Citoesqueleto/fisiología , Uniones Intercelulares/fisiología , Humanos , Fibroblastos/fisiología , Fibroblastos/citología , Movimiento Celular/fisiología , Biología Computacional , Animales , Comunicación Celular/fisiologíaAsunto(s)
Células Epiteliales , Homeostasis , Riñón , Uréter , Proteínas de Unión al GTP rab , Animales , Uréter/embriología , Ratones , Riñón/embriología , Células Epiteliales/metabolismo , Células Epiteliales/fisiología , Proteínas de Unión al GTP rab/metabolismo , Proteínas de Unión al GTP rab/genética , Proteínas de Unión al GTP rab/fisiología , Desarrollo Embrionario , Uniones Intercelulares/fisiologíaRESUMEN
Biological tissues acquire reproducible shapes during development through dynamic cell behaviors. Most of these behaviors involve the remodeling of cell-cell contacts. During epithelial morphogenesis, contractile actomyosin networks remodel cell-cell contacts by shrinking and extending junctions between lateral cell surfaces. However, actomyosin networks not only generate mechanical stresses but also respond to them, confounding our understanding of how mechanical stresses remodel cell-cell contacts. Here, we develop a two-point optical manipulation method to impose different stress patterns on cell-cell contacts in the early epithelium of the Drosophila embryo. The technique allows us to produce junction extension and shrinkage through different push and pull manipulations at the edges of junctions. We use these observations to expand classical vertex-based models of tissue mechanics, incorporating negative and positive mechanosensitive feedback depending on the type of remodeling. In particular, we show that Myosin-II activity responds to junction strain rate and facilitates full junction shrinkage. Altogether our work provides insight into how stress produces efficient deformation of cell-cell contacts in vivo and identifies unanticipated mechanosensitive features of their remodeling.
Asunto(s)
Comunicación Celular , Epitelio , Uniones Intercelulares , Mecanotransducción Celular , Estrés Mecánico , Animales , Actomiosina/fisiología , Comunicación Celular/fisiología , Drosophila , Embrión no Mamífero , Epitelio/fisiología , Uniones Intercelulares/fisiología , Miosina Tipo I/fisiología , Pinzas ÓpticasRESUMEN
BACKGROUND: HAVcR-1 has been linked to cancer aetiology and may regulate junctional complexes, with its role in prostate cancer still unexplored. This study aims to investigate the expression of HAVcR-1 in prostate cancer samples and the exploration of the cellular/molecular impact of HAVcR-1. METHODS: Levels of HAVcR-1 ectodomain in the serum of prostate cancer patients were compared to healthy controls, and assessed as the total protein and gene expression of HAVcR-1 and tissues sections. The manipulation of HAVcR-1 levels within prostate cancer cell lines determined changes in cell behaviour using in vitro cell models and barrier function assays. Protein/phosphoprotein levels were assessed using Western blotting. RESULTS: Levels of HAVcR-1 ectodomain from serum were decreased in patients with prostate cancer. Ectodomain levels correlated with the Gleason score. Histologically, the total protein/gene expression of HAVcR-1 was overexpressed in prostate cancer. The overexpression of HAVcR-1 in prostate cancer cell lines resulted in key changes in cell behaviour and the phosphorylation of ß-catenin with a concurrent decrease in membranous E-cadherin, increased nuclear ß-catenin and increased cyclin D1 protein expression, which were associated with HGF-promoted changes in the barrier function. CONCLUSIONS: HAVcR-1 expression and ectodomain release coincides with the presence of prostate cancer; thus, indicating HAVcR-1 as a potential biomarker to aid in diagnostics, and implicating HAVcR-1 in the dysregulation of junctional complexes.
Asunto(s)
Receptor Celular 1 del Virus de la Hepatitis A , Factor de Crecimiento de Hepatocito , Uniones Intercelulares , Neoplasias de la Próstata , Cadherinas , Línea Celular Tumoral , Humanos , Uniones Intercelulares/fisiología , Masculino , Neoplasias de la Próstata/genética , Receptores Virales , beta CateninaRESUMEN
The human endometrium is characterized by exceptional plasticity, as evidenced by rapid growth and differentiation during the menstrual cycle and fast tissue remodeling during early pregnancy. Past work has rarely addressed the role of cellular mechanics in these processes. It is becoming increasingly clear that sensing and responding to mechanical forces are as significant for cell behavior as biochemical signaling. Here, we provide an overview of experimental evidence and concepts that illustrate how mechanical forces influence endometrial cell behavior during the hormone-driven menstrual cycle and prepare the endometrium for embryo implantation. Given the fundamental species differences during implantation, we restrict the review to the human situation. Novel technologies and devices such as 3D multifrequency magnetic resonance elastography, atomic force microscopy, organ-on-a-chip microfluidic systems, stem-cell-derived organoid formation, and complex 3D co-culture systems have propelled the understanding how endometrial receptivity and blastocyst implantation are regulated in the human uterus. Accumulating evidence has shown that junctional adhesion, cytoskeletal rearrangement, and extracellular matrix stiffness affect the local force balance that regulates endometrial differentiation and blastocyst invasion. A focus of this review is on the hormonal regulation of endometrial epithelial cell mechanics. We discuss potential implications for embryo implantation.
Asunto(s)
Blastocisto/fisiología , Implantación del Embrión , Endometrio/fisiología , Células Epiteliales/fisiología , Mecanotransducción Celular , Ciclo Menstrual/fisiología , Blastocisto/metabolismo , Comunicación Celular , Diferenciación Celular , Proliferación Celular , Endometrio/metabolismo , Células Epiteliales/metabolismo , Matriz Extracelular/fisiología , Femenino , Humanos , Uniones Intercelulares/fisiología , Ciclo Menstrual/metabolismo , Embarazo , Estrés MecánicoRESUMEN
Mechanical forces acting on cell-cell adhesion modulate the barrier function of endothelial cells. The actively remodeled actin cytoskeleton impinges on cell-cell adhesion to counteract external forces. We applied stress on endothelial monolayers by mechanical stretch to uncover the role of BRAF in the stress-induced response. Control cells responded to external forces by organizing and stabilizing actin cables in the stretched cell junctions. This was accompanied by an increase in intercellular gap formation, which was prevented in BRAF knockdown monolayers. In the absence of BRAF, there was excess stress fiber formation due to the enhanced reorganization of actin fibers. Our findings suggest that stretch-induced intercellular gap formation, leading to a decrease in barrier function of blood vessels, can be reverted by BRAF RNAi. This is important when the endothelium experiences changes in external stresses caused by high blood pressure, leading to edema, or by immune or cancer cells in inflammation or metastasis.
Asunto(s)
Células Endoteliales/metabolismo , Uniones Comunicantes/fisiología , Proteínas Proto-Oncogénicas B-raf/metabolismo , Actinas/fisiología , Adhesión Celular/fisiología , Células Cultivadas , Citoesqueleto/fisiología , Células Endoteliales/fisiología , Endotelio Vascular/citología , Humanos , Uniones Intercelulares/fisiología , Fenómenos Mecánicos , Proteínas Proto-Oncogénicas B-raf/fisiologíaRESUMEN
Organ morphogenesis is driven by a wealth of tightly orchestrated cellular behaviors, which ensure proper organ assembly and function. Many of these cell activities involve cell-cell interactions and remodeling of the F-actin cytoskeleton. Here, we analyze the requirement for Rasip1 (Ras-interacting protein 1), an endothelial-specific regulator of junctional dynamics, during blood vessel formation. Phenotype analysis of rasip1 mutants in zebrafish embryos reveals distinct functions of Rasip1 during sprouting angiogenesis, anastomosis and lumen formation. During angiogenic sprouting, loss of Rasip1 causes cell pairing defects due to a destabilization of tricellular junctions, indicating that stable tricellular junctions are essential to maintain multicellular organization within the sprout. During anastomosis, Rasip1 is required to establish a stable apical membrane compartment; rasip1 mutants display ectopic, reticulated junctions and the apical compartment is frequently collapsed. Loss of Ccm1 and Heg1 function mimics the junctional defects of rasip1 mutants. Furthermore, downregulation of ccm1 and heg1 leads to a delocalization of Rasip1 at cell junctions, indicating that junctional tethering of Rasip1 is required for its function in junction formation and stabilization during sprouting angiogenesis.
Asunto(s)
Péptidos y Proteínas de Señalización Intracelular/metabolismo , Neovascularización Fisiológica/fisiología , Proteínas de Pez Cebra/metabolismo , Pez Cebra/metabolismo , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Animales , Comunicación Celular/fisiología , Células Endoteliales/metabolismo , Células Endoteliales/fisiología , Uniones Intercelulares/metabolismo , Uniones Intercelulares/fisiología , Proteínas de la Membrana/metabolismo , Morfogénesis/fisiología , Pez Cebra/fisiologíaRESUMEN
The migration of neutrophils from the blood circulation to sites of infection or injury is a key immune response and requires the breaching of endothelial cells (ECs) that line the inner aspect of blood vessels. Unregulated neutrophil transendothelial cell migration (TEM) is pathogenic, but the molecular basis of its physiological termination remains unknown. Here, we demonstrated that ECs of venules in inflamed tissues exhibited a robust autophagic response that was aligned temporally with the peak of neutrophil trafficking and was strictly localized to EC contacts. Genetic ablation of EC autophagy led to excessive neutrophil TEM and uncontrolled leukocyte migration in murine inflammatory models, while pharmacological induction of autophagy suppressed neutrophil infiltration into tissues. Mechanistically, autophagy regulated the remodeling of EC junctions and expression of key EC adhesion molecules, facilitating their intracellular trafficking and degradation. Collectively, we have identified autophagy as a modulator of EC leukocyte trafficking machinery aimed at terminating physiological inflammation.
Asunto(s)
Autofagia/fisiología , Células Endoteliales/fisiología , Infiltración Neutrófila/fisiología , Migración Transendotelial y Transepitelial/fisiología , Animales , Quimiotaxis de Leucocito/fisiología , Células Endoteliales/patología , Células Endoteliales de la Vena Umbilical Humana/inmunología , Células Endoteliales de la Vena Umbilical Humana/patología , Humanos , Inflamación/inmunología , Inflamación/patología , Uniones Intercelulares/fisiología , Ratones , Ratones Endogámicos C57BL , Neutrófilos/fisiologíaRESUMEN
Complex anatomical form is regulated in part by endogenous physiological communication between cells; however, the dynamics by which gap junctional (GJ) states across tissues regulate morphology are still poorly understood. We employed a biophysical modeling approach combining different signaling molecules (morphogens) to qualitatively describe the anteroposterior and lateral morphology changes in model multicellular systems due to intercellular GJ blockade. The model is based on two assumptions for blocking-induced patterning: (i) the local concentrations of two small antagonistic morphogens diffusing through the GJs along the axial direction, together with that of an independent, uncoupled morphogen concentration along an orthogonal direction, constitute the instructive patterns that modulate the morphological outcomes, and (ii) the addition of an external agent partially blocks the intercellular GJs between neighboring cells and modifies thus the establishment of these patterns. As an illustrative example, we study how the different connectivity and morphogen patterns obtained in presence of a GJ blocker can give rise to novel head morphologies in regenerating planaria. We note that the ability of GJs to regulate the permeability of morphogens post-translationally suggests a mechanism by which different anatomies can be produced from the same genome without the modification of gene-regulatory networks. Conceptually, our model biosystem constitutes a reaction-diffusion information processing mechanism that allows reprogramming of biological morphologies through the external manipulation of the intercellular GJs and the resulting changes in instructive biochemical signals.
Asunto(s)
Uniones Comunicantes/fisiología , Uniones Intercelulares/fisiología , Morfogénesis/fisiología , Planarias/crecimiento & desarrollo , Transducción de Señal/fisiología , Algoritmos , Animales , Difusión , Iones/metabolismo , Modelos Biológicos , Neurotransmisores/metabolismo , Planarias/anatomía & histologíaRESUMEN
Upon inflammation, leukocytes rapidly transmigrate across the endothelium to enter the inflamed tissue. Evidence accumulates that leukocytes use preferred exit sites, alhough it is not yet clear how these hotspots in the endothelium are defined and how they are recognized by the leukocyte. Using lattice light sheet microscopy, we discovered that leukocytes prefer endothelial membrane protrusions at cell junctions for transmigration. Phenotypically, these junctional membrane protrusions are present in an asymmetric manner, meaning that one endothelial cell shows the protrusion and the adjacent one does not. Consequently, leukocytes cross the junction by migrating underneath the protruding endothelial cell. These protrusions depend on Rac1 activity and by using a photo-activatable Rac1 probe, we could artificially generate local exit-sites for leukocytes. Overall, we have discovered a new mechanism that uses local induced junctional membrane protrusions to facilitate/steer the leukocyte escape/exit from inflamed vessel walls.
Asunto(s)
Regulación de la Expresión Génica/fisiología , Uniones Intercelulares/fisiología , Neutrófilos/fisiología , Animales , Línea Celular , Proteínas Fluorescentes Verdes , Células Endoteliales de la Vena Umbilical Humana , Humanos , Masculino , Ratones , Ratones Transgénicos , Microscopía Electrónica de Transmisión , Músculo Esquelético/fisiología , Músculo Esquelético/ultraestructuraRESUMEN
Different body systems (epidermis, respiratory tract, cornea, oral cavity, and gastrointestinal tract) are in continuous direct contact with innocuous and/or potentially harmful external agents, exhibiting dynamic and highly selective interaction throughout the epithelia, which function as both a physical and chemical protective barrier. Resident immune cells in the epithelia are constantly challenged and must distinguish among antigens that must be either tolerated or those to which a response must be mounted for. When such a decision begins to take place in lymphoid foci and/or mucosa-associated lymphoid tissues, the epithelia network of immune surveillance actively dominates both oral and gastrointestinal compartments, which are thought to operate in the same immune continuum. However, anatomical variations clearly differentiate immune processes in both the mouth and gastrointestinal tract that demonstrate a wide array of independent immune responses. From single vs. multiple epithelia cell layers, widespread cell-to-cell junction types, microbial-associated recognition receptors, dendritic cell function as well as related signaling, the objective of this review is to specifically contrast the current knowledge of oral versus gut immune niches in the context of epithelia/lymphoid foci/MALT local immunity and systemic output. Related differences in 1) anatomy 2) cell-to-cell communication 3) antigen capture/processing/presentation 4) signaling in regulatory vs. proinflammatory responses and 5) systemic output consequences and its relations to disease pathogenesis are discussed.
Asunto(s)
Alostasis , Homeostasis , Inmunidad Mucosa/inmunología , Vigilancia Inmunológica/inmunología , Mucosa Intestinal/inmunología , Mucosa Bucal/inmunología , Inmunidad Adaptativa , Animales , Presentación de Antígeno , Traslocación Bacteriana/inmunología , Moléculas de Adhesión Celular/fisiología , Comunicación Celular , Células Dendríticas/inmunología , Disbiosis/inmunología , Células Epiteliales/inmunología , Humanos , Inflamación , Uniones Intercelulares/fisiología , Mucosa Intestinal/citología , Microbiota , Mucosa Bucal/citología , Moco/fisiología , Especificidad de Órganos , Saliva/inmunología , Transducción de SeñalRESUMEN
Muscarinic acetylcholine receptor (mAChR) antagonists have been reported to decrease male fertility; however, the roles of mAChRs in spermatogenesis and the underlying mechanisms are not understood yet. During spermatogenesis, extensive remodeling between Sertoli cells and/or germ cells interfaces takes place to accommodate the transport of developing germ cells across the blood-testis barrier (BTB) and adluminal compartment. The cell-cell junctions play a vital role in the spermatogenesis process. This study used ICR male mice and spermatogonial cells (C18-4) and Sertoli cells (TM-4). shRNA of control or M5 gene was injected into 5-week-old ICR mice testes. Ten days post-viral grafting, mice were deeply anesthetized with pentobarbital and the testes were collected. One testicle was fresh frozen for RNA-seq analysis or Western blotting (WB). The second testicle was fixed for immunofluorescence staining (IHF). C18-4 or TM-4 cells were treated with shRNA of control or M5 gene. Then, the cells were collected for RNA-seq analysis, WB, or IHF. Knockdown of mAChR M5 disrupted mouse spermatogenesis and damaged the actin-based cytoskeleton and many types of junction proteins in both Sertoli cells and germ cells. M5 knockdown decreased Phldb2 expression in both germ cells and Sertoli cells which suggested that Phldb2 may be involved in cytoskeleton and cell-cell junction formation to regulate spermatogenesis. Our investigation has elucidated a novel role for mAChR M5 in the regulation of spermatogenesis through the interactions of Phldb2 and cell-cell junctions. M5 may be an attractive future therapeutic target in the treatment of male reproductive disorders.
Asunto(s)
Barrera Hematotesticular , Uniones Intercelulares/fisiología , Proteínas de la Membrana/metabolismo , Receptor Muscarínico M5/metabolismo , Células de Sertoli/citología , Espermatogénesis , Testículo/citología , Citoesqueleto de Actina , Animales , Masculino , Proteínas de la Membrana/genética , Ratones , Ratones Endogámicos ICR , Microtúbulos/metabolismo , Receptor Muscarínico M5/genética , Células de Sertoli/metabolismo , Testículo/metabolismoRESUMEN
Transendothelial migration (TEM) of neutrophils under blood flow is critical in the inflammatory cascade. However, the role of endothelial plasticity in this process is not fully understood. Therefore, we used an in vitro model to test the dynamics of human polymorphonuclear neutrophil (PMN) TEM across lipopolysaccharide-treated human umbilical vein endothelial cell (HUVEC) monolayers. Interestingly, shRNA-E-selectin knockdown in HUVECs destabilized endothelial junctional integrity by reducing actin branching and increasing stress fiber at cell-cell junctions. This process is accomplished by downregulating the activation of cortactin and Arp2/3, which in turn alters the adhesive function of VE-cadherin, enhancing PMN transmigration. Meanwhile, redundant P-selectins possess overlapping functions in E-selectin-mediated neutrophil adhesion, and transmigration. These results demonstrate, to our knowledge, for the first time, that E-selectins negatively regulate neutrophil transmigration through alterations in endothelial plasticity. Furthermore, it improves our understanding of the mechanisms underlying actin remodeling, and junctional integrity, in endothelial cells mediating leukocyte TEM.
Asunto(s)
Movimiento Celular , Selectina E/metabolismo , Endotelio Vascular/fisiología , Uniones Intercelulares/fisiología , Neutrófilos/fisiología , Migración Transendotelial y Transepitelial , Proteína 2 Relacionada con la Actina/genética , Proteína 2 Relacionada con la Actina/metabolismo , Proteína 3 Relacionada con la Actina/genética , Proteína 3 Relacionada con la Actina/metabolismo , Células Cultivadas , Selectina E/genética , Endotelio Vascular/citología , Humanos , Neutrófilos/citología , SeudópodosRESUMEN
Recognizing the crucial role of mechanical regulation and forces in tissue development and homeostasis has stirred a demand for in situ measurement of forces and stresses. Among emerging techniques, the use of cell geometry to infer cell junction tensions, cell pressures and tissue stress has gained popularity owing to the development of computational analyses. This approach is non-destructive and fast, and statistically validated based on comparisons with other techniques. However, its qualitative and quantitative limitations, in theory as well as in practice, should be examined with care. In this Primer, we summarize the underlying principles and assumptions behind stress inference, discuss its validity criteria and provide guidance to help beginners make the appropriate choice of its variants. We extend our discussion from two-dimensional stress inference to three dimensional, using the early mouse embryo as an example, and list a few possible extensions. We hope to make stress inference more accessible to the scientific community and trigger a broader interest in using this technique to study mechanics in development.
Asunto(s)
Uniones Intercelulares/fisiología , Animales , Embrión de Mamíferos/fisiología , Fenómenos Mecánicos , Presión , Estrés MecánicoRESUMEN
Epithelia are continuously self-renewed, but how epithelial integrity is maintained during the morphological changes that cells undergo in mitosis is not well understood. Here, we show that as epithelial cells round up when they enter mitosis, they exert tensile forces on neighboring cells. We find that mitotic cell-cell junctions withstand these tensile forces through the mechanosensitive recruitment of the actin-binding protein vinculin to cadherin-based adhesions. Surprisingly, vinculin that is recruited to mitotic junctions originates selectively from the neighbors of mitotic cells, resulting in an asymmetric composition of cadherin junctions. Inhibition of junctional vinculin recruitment in neighbors of mitotic cells results in junctional breakage and weakened epithelial barrier. Conversely, the absence of vinculin from the cadherin complex in mitotic cells is necessary to successfully undergo mitotic rounding. Our data thus identify an asymmetric mechanoresponse at cadherin adhesions during mitosis, which is essential to maintain epithelial integrity while at the same time enable the shape changes of mitotic cells.
Asunto(s)
Uniones Adherentes/fisiología , Células Epiteliales/fisiología , Epitelio/fisiología , Uniones Intercelulares/fisiología , Mitosis/fisiología , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Uniones Adherentes/metabolismo , Animales , Cadherinas/metabolismo , Línea Celular , Perros , Células Epiteliales/metabolismo , Epitelio/metabolismo , Uniones Intercelulares/metabolismo , Células de Riñón Canino Madin Darby , Proteínas de Microfilamentos/metabolismoRESUMEN
The formation of an epithelial tube is a fundamental process for organogenesis. During Drosophila embryonic salivary gland (SG) invagination, Folded gastrulation (Fog)-dependent Rho-associated kinase (Rok) promotes contractile apical myosin formation to drive apical constriction. Microtubules (MTs) are also crucial for this process and are required for forming and maintaining apicomedial myosin. However, the underlying mechanism that coordinates actomyosin and MT networks still remains elusive. Here, we show that MT-dependent intracellular trafficking regulates apical constriction during SG invagination. Key components involved in protein trafficking, such as Rab11 and Nuclear fallout (Nuf), are apically enriched near the SG invagination pit in a MT-dependent manner. Disruption of the MT networks or knockdown of Rab11 impairs apicomedial myosin formation and apical constriction. We show that MTs and Rab11 are required for apical enrichment of the Fog ligand and the continuous distribution of the apical determinant protein Crumbs (Crb) and the key adherens junction protein E-Cadherin (E-Cad) along junctions. Targeted knockdown of crb or E-Cad in the SG disrupts apical myosin networks and results in apical constriction defects. Our data suggest a role of MT- and Rab11-dependent intracellular trafficking in regulating actomyosin networks and cell junctions to coordinate cell behaviors during tubular organ formation.
Asunto(s)
Proteínas de Drosophila/fisiología , Drosophila/embriología , Microtúbulos/fisiología , Glándulas Salivales/embriología , Proteínas de Unión al GTP rab/fisiología , Citoesqueleto de Actina/fisiología , Actomiosina/fisiología , Animales , Transporte Biológico , Cadherinas/fisiología , Proteínas de Drosophila/genética , Dineínas/fisiología , Gastrulación , Técnicas de Silenciamiento del Gen , Uniones Intercelulares/fisiología , Miosinas/fisiología , Proteínas Nucleares/fisiología , Proteínas de Unión al GTP rab/genéticaRESUMEN
How global patterns emerge from individual cell behaviors is poorly understood. In the Xenopus embryonic epidermis, multiciliated cells (MCCs) are born in a random pattern within an inner mesenchymal layer and subsequently intercalate at regular intervals into an outer epithelial layer. Using video microscopy and mathematical modeling, we found that regular pattern emergence involves mutual repulsion among motile immature MCCs and affinity toward outer-layer intercellular junctions. Consistently, Arp2/3-mediated actin remodeling is required for MCC patterning. Mechanistically, we show that the Kit tyrosine kinase receptor, expressed in MCCs, and its ligand Scf, expressed in outer-layer cells, are both required for regular MCC distribution. Membrane-associated Scf behaves as a potent adhesive cue for MCCs, while its soluble form promotes their mutual repulsion. Finally, Kit expression is sufficient to confer order to a disordered heterologous cell population. This work reveals how a single signaling system can implement self-organized large-scale patterning.
Asunto(s)
Complejo 2-3 Proteico Relacionado con la Actina/metabolismo , Cilios/fisiología , Embrión no Mamífero/fisiología , Células Epidérmicas/fisiología , Uniones Intercelulares/fisiología , Proteínas Proto-Oncogénicas c-kit/metabolismo , Factor de Células Madre/metabolismo , Proteínas de Xenopus/metabolismo , Complejo 2-3 Proteico Relacionado con la Actina/genética , Actinas/metabolismo , Animales , Embrión no Mamífero/citología , Células Epidérmicas/citología , Femenino , Regulación del Desarrollo de la Expresión Génica , Proteínas Proto-Oncogénicas c-kit/genética , Transducción de Señal , Factor de Células Madre/genética , Proteínas de Xenopus/genética , Xenopus laevisRESUMEN
Apical-basal polarity is a key feature of most epithelial cells and it is regulated by highly conserved protein complexes. In mammalian podocytes, which emerge from columnar epithelial cells, this polarity is preserved and the tight junctions are converted to the slit diaphragms, establishing the filtration barrier. In Drosophila, nephrocytes show several structural and functional similarities with mammalian podocytes and proximal tubular cells. However, in contrast to podocytes, little is known about the role of apical-basal polarity regulators in these cells. In this study, we used expansion microscopy and found the apical polarity determinants of the PAR/aPKC and Crb-complexes to be predominantly targeted to the cell cortex in proximity to the nephrocyte diaphragm, whereas basolateral regulators also accumulate intracellularly. Knockdown of PAR-complex proteins results in severe endocytosis and nephrocyte diaphragm defects, which is due to impaired aPKC recruitment to the plasma membrane. Similar, downregulation of most basolateral polarity regulators disrupts Nephrin localization but had surprisingly divergent effects on endocytosis. Our findings suggest that morphology and slit diaphragm assembly/maintenance of nephrocytes is regulated by classical apical-basal polarity regulators, which have distinct functions in endocytosis.
Asunto(s)
Polaridad Celular , Proteínas de Drosophila/metabolismo , Endocitosis , Uniones Intercelulares/fisiología , Proteínas de la Membrana/metabolismo , Podocitos/fisiología , Animales , Proteínas de Drosophila/genética , Drosophila melanogaster , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Podocitos/citología , Podocitos/metabolismo , Proteína Quinasa C/genética , Proteína Quinasa C/metabolismoRESUMEN
Epithelial and endothelial cell-cell contacts are established and maintained by several intercellular junctional complexes. These structurally and biochemically differentiated regions on the plasma membrane primarily include tight junctions (TJs), and anchoring junctions. While the adherens junctions (AJs) provide essential adhesive and mechanical properties, TJs hold the cells together and form a near leak-proof intercellular seal by the fusion of adjacent cell membranes. AJs and TJs play essential roles in vascular permeability. Considering their involvement in several key cellular functions such as barrier formation, proliferation, migration, survival, and differentiation, further research is warranted on the composition and signaling pathways regulating cell-cell junctions to develop novel therapeutics for diseases such as organ injuries. The current review article presents our current state of knowledge on various cell-cell junctions, their molecular composition, and mechanisms regulating their expression and function in endothelial and epithelial cells.