RESUMEN
Pediatric cardiomyopathy (CM) represents a group of rare, severe disorders that affect the myocardium. To date, the etiology and mechanisms underlying pediatric CM are incompletely understood, hampering accurate diagnosis and individualized therapy development. Here, we identified biallelic variants in the highly conserved flightless-I (FLII) gene in 3 families with idiopathic, early-onset dilated CM. We demonstrated that patient-specific FLII variants, when brought into the zebrafish genome using CRISPR/Cas9 genome editing, resulted in the manifestation of key aspects of morphological and functional abnormalities of the heart, as observed in our patients. Importantly, using these genetic animal models, complemented with in-depth loss-of-function studies, we provided insights into the function of Flii during ventricular chamber morphogenesis in vivo, including myofibril organization and cardiomyocyte cell adhesion, as well as trabeculation. In addition, we identified Flii function to be important for the regulation of Notch and Hippo signaling, crucial pathways associated with cardiac morphogenesis and function. Taken together, our data provide experimental evidence for a role for FLII in the pathogenesis of pediatric CM and report biallelic variants as a genetic cause of pediatric CM.
Asunto(s)
Cardiomiopatías , Proteínas de Microfilamentos , Animales , Adhesión Celular/genética , Proteínas de Microfilamentos/genética , Miocitos Cardíacos/metabolismo , Miofibrillas/metabolismo , Pez Cebra/genética , Transactivadores , Cardiomiopatías/genéticaRESUMEN
Restoring damaged ß-cells in diabetic patients by harnessing the plasticity of other pancreatic cells raises the questions of the efficiency of the process and of the functionality of the new Insulin-expressing cells. To overcome the weak regenerative capacity of mammals, we used regeneration-prone zebrafish to study ß-cells arising following destruction. We show that most new insulin cells differ from the original ß-cells as they coexpress Somatostatin and Insulin. These bihormonal cells are abundant, functional and able to normalize glycemia. Their formation in response to ß-cell destruction is fast, efficient, and age-independent. Bihormonal cells are transcriptionally close to a subset of δ-cells that we identified in control islets and that are characterized by the expression of somatostatin 1.1 (sst1.1) and by genes essential for glucose-induced Insulin secretion in ß-cells such as pdx1, slc2a2 and gck. We observed in vivo the conversion of monohormonal sst1.1-expressing cells to sst1.1+ ins + bihormonal cells following ß-cell destruction. Our findings support the conclusion that sst1.1 δ-cells possess a pro-ß identity enabling them to contribute to the neogenesis of Insulin-producing cells during regeneration. This work unveils that abundant and functional bihormonal cells benefit to diabetes recovery in zebrafish.
Asunto(s)
Diabetes Mellitus Experimental/metabolismo , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Células Secretoras de Somatostatina/metabolismo , Animales , Femenino , Masculino , Páncreas/citología , Somatostatina/metabolismo , Pez CebraRESUMEN
Lung epithelial progenitors differentiate into alveolar type 1 (AT1) and type 2 (AT2) cells. These cells form the air-blood interface and secrete surfactant, respectively, and are essential for lung maturation and function. Current protocols to derive and culture alveolar cells do not faithfully recapitulate the architecture of the distal lung, which influences cell fate patterns in vivo. Here, we report serum-free conditions that allow for growth and differentiation of mouse distal lung epithelial progenitors. We find that Collagen I promotes the differentiation of flattened, polarized AT1 cells. Using these organoids, we performed a chemical screen to investigate WNT signaling in epithelial differentiation. We identify an association between Casein Kinase activity and maintenance of an AT2 expression signature; Casein Kinase inhibition leads to an increase in AT1/progenitor cell ratio. These organoids provide a simplified model of alveolar differentiation and constitute a scalable screening platform to identify and analyze cell differentiation mechanisms.
Asunto(s)
Diferenciación Celular , Alveolos Pulmonares/citología , Células Madre/citología , Animales , Caseína Quinasas/antagonistas & inhibidores , Caseína Quinasas/metabolismo , Células Cultivadas , Colágeno Tipo I/metabolismo , Medio de Cultivo Libre de Suero , Células Epiteliales/citología , Células Epiteliales/metabolismo , Marcadores Genéticos , Ratones , Ratones Endogámicos C57BL , Alveolos Pulmonares/embriología , Alveolos Pulmonares/enzimología , Alveolos Pulmonares/metabolismo , Transcripción Genética , Vía de Señalización WntRESUMEN
To investigate the role of the vasculature in pancreatic ß-cell regeneration, we crossed a zebrafish ß-cell ablation model into the avascular npas4l mutant (i.e. cloche). Surprisingly, ß-cell regeneration increased markedly in npas4l mutants owing to the ectopic differentiation of ß-cells in the mesenchyme, a phenotype not previously reported in any models. The ectopic ß-cells expressed endocrine markers of pancreatic ß-cells, and also responded to glucose with increased calcium influx. Through lineage tracing, we determined that the vast majority of these ectopic ß-cells has a mesodermal origin. Notably, ectopic ß-cells were found in npas4l mutants as well as following knockdown of the endothelial/myeloid determinant Etsrp. Together, these data indicate that under the perturbation of endothelial/myeloid specification, mesodermal cells possess a remarkable plasticity enabling them to form ß-cells, which are normally endodermal in origin. Understanding the restriction of this differentiation plasticity will help exploit an alternative source for ß-cell regeneration.
Asunto(s)
Diferenciación Celular , Células Secretoras de Insulina/fisiología , Mesodermo/embriología , Regeneración , Pez Cebra/embriología , Animales , Endotelio/fisiología , Insulinas/metabolismo , Pez Cebra/fisiologíaRESUMEN
The transcription factor Snai1, a well-known regulator of epithelial-to-mesenchymal transition, has been implicated in early cardiac morphogenesis as well as in cardiac valve formation. However, a role for Snai1 in regulating other aspects of cardiac morphogenesis has not been reported. Using genetic, transcriptomic, and chimeric analyses in zebrafish, we find that Snai1b is required in cardiomyocytes for myocardial wall integrity. Loss of snai1b increases the frequency of cardiomyocyte extrusion away from the cardiac lumen. Extruding cardiomyocytes exhibit increased actomyosin contractility basally as revealed by enrichment of p-myosin and α-catenin epitope α-18, as well as disrupted intercellular junctions. Transcriptomic analysis of wild-type and snai1b mutant hearts revealed the dysregulation of intermediate filament genes, including desmin b (desmb) upregulation. Cardiomyocyte-specific desmb overexpression caused increased cardiomyocyte extrusion, recapitulating the snai1b mutant phenotype. Altogether, these results indicate that Snai1 maintains the integrity of the myocardial epithelium, at least in part by repressing desmb expression.
Asunto(s)
Regulación de la Expresión Génica , Corazón/fisiología , Filamentos Intermedios/genética , Factores de Transcripción de la Familia Snail/genética , Proteínas de Pez Cebra/genética , Pez Cebra/fisiología , Animales , Miocardio/metabolismo , Factores de Transcripción de la Familia Snail/metabolismo , Pez Cebra/genética , Proteínas de Pez Cebra/metabolismoRESUMEN
Ankyrin repeat domain 1 (ANKRD1) is a functionally pleiotropic protein found in the nuclei and sarcomeres of cardiac and skeletal muscles, with a proposed role in linking myofibrilar stress and transcriptional regulation. Rapid upregulation of its expression in response to both physiological and pathological stress supports the involvement of ANKRD1 in muscle tissue adaptation and remodeling. However, the exact role of ANKRD1 remains poorly understood. To begin to investigate its function at higher resolution, we have generated and characterized a TgBAC(ankrd1a:EGFP) zebrafish line. This reporter line displays transgene expression in slow skeletal muscle fibers during development and exercise responsiveness in adult cardiac muscle. To better understand the role of Ankrd1a in pathological conditions in adult zebrafish, we assessed ankrd1a expression after cardiac ventricle cryoinjury and observed localized upregulation in cardiomyocytes in the border zone. We show that this expression in injured hearts is recapitulated by the TgBAC(ankrd1a:EGFP) reporter. Our results identify novel expression domains of ankrd1a and suggest an important role for Ankrd1a in the early stress response and regeneration of cardiac tissue. This new reporter line will help decipher the role of Ankrd1a in striated muscle stress response, including after cardiac injury.
Asunto(s)
Proteínas de Unión al ADN/genética , Proteínas Musculares/genética , Miocitos Cardíacos/metabolismo , Proteínas Nucleares/genética , Estrés Fisiológico/genética , Proteínas de Pez Cebra/genética , Pez Cebra/genética , Animales , Animales Modificados Genéticamente , Proteínas de Unión al ADN/metabolismo , Embrión no Mamífero , Regulación del Desarrollo de la Expresión Génica , Genes Reporteros , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Ventrículos Cardíacos/crecimiento & desarrollo , Ventrículos Cardíacos/lesiones , Ventrículos Cardíacos/metabolismo , Desarrollo de Músculos/genética , Proteínas Musculares/metabolismo , Músculo Esquelético/crecimiento & desarrollo , Músculo Esquelético/metabolismo , Miocardio/metabolismo , Miocitos Cardíacos/patología , Proteínas Nucleares/metabolismo , Pez Cebra/crecimiento & desarrollo , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismoRESUMEN
To form new blood vessels (angiogenesis), endothelial cells (ECs) must be activated and acquire highly migratory and proliferative phenotypes. However, the molecular mechanisms that govern these processes are incompletely understood. Here, we show that Apelin signaling functions to drive ECs into such an angiogenic state. Zebrafish lacking Apelin signaling exhibit defects in endothelial tip cell morphology and sprouting. Using transplantation experiments, we find that in mosaic vessels, wild-type ECs leave the dorsal aorta (DA) and form new vessels while neighboring ECs defective in Apelin signaling remain in the DA. Mechanistically, Apelin signaling enhances glycolytic activity in ECs at least in part by increasing levels of the growth-promoting transcription factor c-Myc. Moreover, APELIN expression is regulated by Notch signaling in human ECs, and its function is required for the hypersprouting phenotype in Delta-like 4 (Dll4) knockdown zebrafish embryos. These data provide new insights into fundamental principles of blood vessel formation and Apelin signaling, enabling a better understanding of vascular growth in health and disease.
Asunto(s)
Vasos Sanguíneos/crecimiento & desarrollo , Quimiocinas/genética , Morfogénesis/genética , Transducción de Señal/genética , Proteínas de Pez Cebra/genética , Pez Cebra/genética , Animales , Vasos Sanguíneos/metabolismo , Quimiocinas/metabolismo , Células Endoteliales/metabolismo , Proteínas de Pez Cebra/metabolismoRESUMEN
The development of the cardiac outflow tract (OFT), which connects the heart to the great arteries, relies on a complex crosstalk between endothelial (ECs) and smooth muscle (SMCs) cells. Defects in OFT development can lead to severe malformations, including aortic aneurysms, which are frequently associated with impaired TGF-ß signaling. To better understand the role of TGF-ß signaling in OFT formation, we generated zebrafish lacking the TGF-ß receptor Alk5 and found a strikingly specific dilation of the OFT: alk5-/- OFTs exhibit increased EC numbers as well as extracellular matrix (ECM) and SMC disorganization. Surprisingly, endothelial-specific alk5 overexpression in alk5-/- rescues the EC, ECM, and SMC defects. Transcriptomic analyses reveal downregulation of the ECM gene fibulin-5, which when overexpressed in ECs ameliorates OFT morphology and function. These findings reveal a new requirement for endothelial TGF-ß signaling in OFT morphogenesis and suggest an important role for the endothelium in the etiology of aortic malformations.
Asunto(s)
Endotelio Vascular/metabolismo , Miocitos del Músculo Liso/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Animales , Aorta/citología , Aorta/metabolismo , Endotelio Vascular/citología , Ventrículos Cardíacos/citología , Ventrículos Cardíacos/metabolismo , Receptor Tipo I de Factor de Crecimiento Transformador beta/metabolismo , Proteína smad3/metabolismo , Pez Cebra , Proteínas de Pez Cebra/metabolismoRESUMEN
Cardiac metabolism plays a crucial role in producing sufficient energy to sustain cardiac function. However, the role of metabolism in different aspects of cardiomyocyte regeneration remains unclear. Working with the adult zebrafish heart regeneration model, we first find an increase in the levels of mRNAs encoding enzymes regulating glucose and pyruvate metabolism, including pyruvate kinase M1/2 (Pkm) and pyruvate dehydrogenase kinases (Pdks), especially in tissues bordering the damaged area. We further find that impaired glycolysis decreases the number of proliferating cardiomyocytes following injury. These observations are supported by analyses using loss-of-function models for the metabolic regulators Pkma2 and peroxisome proliferator-activated receptor gamma coactivator 1 alpha. Cardiomyocyte-specific loss- and gain-of-function manipulations of pyruvate metabolism using Pdk3 as well as a catalytic subunit of the pyruvate dehydrogenase complex (PDC) reveal its importance in cardiomyocyte dedifferentiation and proliferation after injury. Furthermore, we find that PDK activity can modulate cell cycle progression and protrusive activity in mammalian cardiomyocytes in culture. Our findings reveal new roles for cardiac metabolism and the PDK-PDC axis in cardiomyocyte behavior following cardiac injury.
Asunto(s)
Miocitos Cardíacos , Pez Cebra , Animales , Proliferación Celular , Glucólisis , Miocitos Cardíacos/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Pez Cebra/metabolismoRESUMEN
Transcriptional adaptation is a recently described phenomenon by which a mutation in one gene leads to the transcriptional modulation of related genes, termed adapting genes. At the molecular level, it has been proposed that the mutant mRNA, rather than the loss of protein function, activates this response. While several examples of transcriptional adaptation have been reported in zebrafish embryos and in mouse cell lines, it is not known whether this phenomenon is observed across metazoans. Here we report transcriptional adaptation in C. elegans, and find that this process requires factors involved in mutant mRNA decay, as in zebrafish and mouse. We further uncover a requirement for Argonaute proteins and Dicer, factors involved in small RNA maturation and transport into the nucleus. Altogether, these results provide evidence for transcriptional adaptation in C. elegans, a powerful model to further investigate underlying molecular mechanisms.
Asunto(s)
Adaptación Biológica/genética , Caenorhabditis elegans/genética , Regulación de la Expresión Génica/genética , Transcripción Genética/genética , Animales , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , ARN Helicasas DEAD-box/genética , ARN Helicasas DEAD-box/metabolismo , Mutación/genética , Estabilidad del ARN/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ribonucleasa III/genética , Ribonucleasa III/metabolismoRESUMEN
The vertebral column or spine assembles around the notochord rod which contains a core made of large vacuolated cells. Each vacuolated cell possesses a single ï¬uid-ï¬lled vacuole, and loss or fragmentation of these vacuoles in zebrafish leads to spine kinking. Here, we identified a mutation in the kinase gene dstyk that causes fragmentation of notochord vacuoles and a severe congenital scoliosis-like phenotype in zebrafish. Live imaging revealed that Dstyk regulates fusion of membranes with the vacuole. We find that localized disruption of notochord vacuoles causes vertebral malformation and curving of the spine axis at those sites. Accordingly, in dstyk mutants the spine curves increasingly over time as vertebral bone formation compresses the notochord asymmetrically, causing vertebral malformations and kinking of the axis. Together, our data show that notochord vacuoles function as a hydrostatic scaffold that guides symmetrical growth of vertebrae and spine formation.
Asunto(s)
Notocorda/metabolismo , Columna Vertebral/crecimiento & desarrollo , Vacuolas/metabolismo , Pez Cebra/embriología , Animales , Regulación del Desarrollo de la Expresión Génica , Mutación , Proteína Serina-Treonina Quinasas de Interacción con Receptores/genética , Proteínas de Pez Cebra/genéticaRESUMEN
During cardiac development, cardiomyocytes form complex inner wall structures called trabeculae. Despite significant investigation into this process, the potential role of metabolism has not been addressed. Using single cell resolution imaging in zebrafish, we find that cardiomyocytes seeding the trabecular layer actively change their shape while compact layer cardiomyocytes remain static. We show that Erbb2 signaling, which is required for trabeculation, activates glycolysis to support changes in cardiomyocyte shape and behavior. Pharmacological inhibition of glycolysis impairs cardiac trabeculation, and cardiomyocyte-specific loss- and gain-of-function manipulations of glycolysis decrease and increase trabeculation, respectively. In addition, loss of the glycolytic enzyme pyruvate kinase M2 impairs trabeculation. Experiments with rat neonatal cardiomyocytes in culture further support these observations. Our findings reveal new roles for glycolysis in regulating cardiomyocyte behavior during cardiac wall morphogenesis.
Asunto(s)
Corazón/embriología , Corazón/crecimiento & desarrollo , Morfogénesis/fisiología , Miocitos Cardíacos/metabolismo , Pez Cebra/embriología , Pez Cebra/crecimiento & desarrollo , Pez Cebra/metabolismo , Animales , Animales Modificados Genéticamente , Proliferación Celular , Regulación del Desarrollo de la Expresión Génica , Genes erbB-2/genética , Glucólisis , Corazón/fisiología , Modelos Animales , Morfogénesis/genética , Organogénesis/genética , Organogénesis/fisiología , Ratas , Transducción de Señal/fisiología , Pez Cebra/genética , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/metabolismoRESUMEN
In recent years, there has been increasing interest in the role of lymphatics in organ repair and regeneration, due to their importance in immune surveillance and fluid homeostasis. Experimental approaches aimed at boosting lymphangiogenesis following myocardial infarction in mice, were shown to promote healing of the heart. Yet, the mechanisms governing cardiac lymphatic growth remain unclear. Here, we identify two distinct lymphatic populations in the hearts of zebrafish and mouse, one that forms through sprouting lymphangiogenesis, and the other by coalescence of isolated lymphatic cells. By tracing the development of each subset, we reveal diverse cellular origins and differential response to signaling cues. Finally, we show that lymphatic vessels are required for cardiac regeneration in zebrafish as mutants lacking lymphatics display severely impaired regeneration capabilities. Overall, our results provide novel insight into the mechanisms underlying lymphatic formation during development and regeneration, opening new avenues for interventions targeting specific lymphatic populations.
Asunto(s)
Corazón/fisiología , Linfangiogénesis/fisiología , Vasos Linfáticos/fisiología , Miocardio/metabolismo , Regeneración/fisiología , Transducción de Señal/fisiología , Animales , Animales Modificados Genéticamente , Corazón/embriología , Corazón/crecimiento & desarrollo , Linfangiogénesis/genética , Sistema Linfático/citología , Sistema Linfático/metabolismo , Sistema Linfático/fisiología , Vasos Linfáticos/metabolismo , Ratones Noqueados , Ratones Transgénicos , Mutación , Infarto del Miocardio/fisiopatología , Regeneración/genética , Transducción de Señal/genética , Pez CebraRESUMEN
Pathways modulating glucose homeostasis independently of insulin would open new avenues to combat insulin resistance and diabetes. Here, we report the establishment, characterization, and use of a vertebrate 'insulin-free' model to identify insulin-independent modulators of glucose metabolism. insulin knockout zebrafish recapitulate core characteristics of diabetes and survive only up to larval stages. Utilizing a highly efficient endoderm transplant technique, we generated viable chimeric adults that provide the large numbers of insulin mutant larvae required for our screening platform. Using glucose as a disease-relevant readout, we screened 2233 molecules and identified three that consistently reduced glucose levels in insulin mutants. Most significantly, we uncovered an insulin-independent beneficial role for androgen receptor antagonism in hyperglycemia, mostly by reducing fasting glucose levels. Our study proposes therapeutic roles for androgen signaling in diabetes and, more broadly, offers a novel in vivo model for rapid screening and decoupling of insulin-dependent and -independent mechanisms.
Asunto(s)
Glucosa/metabolismo , Hiperglucemia/genética , Insulina/genética , Receptores Androgénicos/genética , Antagonistas de Receptores Androgénicos/química , Antagonistas de Receptores Androgénicos/metabolismo , Animales , Modelos Animales de Enfermedad , Técnicas de Inactivación de Genes , Homeostasis , Hiperglucemia/metabolismo , Hiperglucemia/patología , Resistencia a la Insulina/genética , Receptores Androgénicos/química , Transducción de Señal/genética , Pez Cebra/genéticaRESUMEN
Pitx2c, a homeodomain transcription factor, is classically known for its left-right patterning role. However, an early wave of pitx2 expression occurs at the onset of gastrulation in several species, indicating a possible earlier role that remains relatively unexplored. Here we show that in zebrafish, maternal-zygotic (MZ) pitx2c mutants exhibit a shortened body axis indicative of convergence and extension (CE) defects. Live imaging reveals that MZpitx2c mutants display less persistent mesendodermal migration during late stages of gastrulation. Transplant data indicate that Pitx2c functions cell non-autonomously to regulate this cell behavior by modulating cell shape and protrusive activity. Using transcriptomic analyses and candidate gene approaches, we identify transcriptional changes in components of the chemokine-ECM-integrin dependent mesendodermal migration network. Together, our results define pathways downstream of Pitx2c that are required during early embryogenesis and reveal novel functions for Pitx2c as a regulator of morphogenesis.
Asunto(s)
Movimiento Celular/genética , Desarrollo Embrionario/genética , Células Epiteliales/metabolismo , Regulación del Desarrollo de la Expresión Génica , Factores de Transcripción/genética , Proteínas de Pez Cebra/genética , Pez Cebra/genética , Animales , Animales Modificados Genéticamente , Tipificación del Cuerpo/genética , Forma de la Célula , Quimiocinas/genética , Quimiocinas/metabolismo , Embrión no Mamífero , Endodermo/citología , Endodermo/metabolismo , Células Epiteliales/citología , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , Gastrulación/genética , Integrinas/genética , Integrinas/metabolismo , Mutación , Notocorda/citología , Notocorda/metabolismo , Imagen de Lapso de Tiempo , Factores de Transcripción/metabolismo , Transcriptoma , Pez Cebra/crecimiento & desarrollo , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismo , Cigoto/citología , Cigoto/crecimiento & desarrollo , Cigoto/metabolismoRESUMEN
Pancreatic islets are innervated by autonomic and sensory nerves that influence their function. Analyzing the innervation process should provide insight into the nerve-endocrine interactions and their roles in development and disease. Here, using in vivo time-lapse imaging and genetic analyses in zebrafish, we determined the events leading to islet innervation. Comparable neural density in the absence of vasculature indicates that it is dispensable for early pancreatic innervation. Neural crest cells are in close contact with endocrine cells early in development. We find these cells give rise to neurons that extend axons toward the islet as they surprisingly migrate away. Specific ablation of these neurons partly prevents other neurons from migrating away from the islet resulting in diminished innervation. Thus, our studies establish the zebrafish as a model to interrogate mechanisms of organ innervation, and reveal a novel mode of innervation whereby neurons establish connections with their targets before migrating away.
Asunto(s)
Células Endocrinas/fisiología , Islotes Pancreáticos/inervación , Red Nerviosa/fisiología , Cresta Neural/fisiología , Sistema Nervioso Parasimpático/fisiología , Transmisión Sináptica/fisiología , Animales , Animales Modificados Genéticamente , Biomarcadores/metabolismo , Comunicación Celular , Diferenciación Celular , Movimiento Celular , Embrión no Mamífero , Células Endocrinas/citología , Expresión Génica , Insulina/genética , Insulina/metabolismo , Islotes Pancreáticos/citología , Islotes Pancreáticos/fisiología , Red Nerviosa/citología , Cresta Neural/citología , Sistema Nervioso Parasimpático/citología , Somatostatina/genética , Somatostatina/metabolismo , Tubulina (Proteína)/genética , Tubulina (Proteína)/metabolismo , Pez CebraRESUMEN
The ultimate formation of a four-chambered heart allowing the separation of the pulmonary and systemic circuits was key for the evolutionary success of tetrapods. Complex processes of cell diversification and tissue morphogenesis allow the left and right cardiac compartments to become distinct but remain poorly understood. Here, we describe an unexpected laterality in the single zebrafish atrium analogous to that of the two atria in amniotes, including mammals. This laterality appears to derive from an embryonic antero-posterior asymmetry revealed by the expression of the transcription factor gene meis2b. In adult zebrafish hearts, meis2b expression is restricted to the left side of the atrium where it controls the expression of pitx2c, a regulator of left atrial identity in mammals. Altogether, our studies suggest that the multi-chambered atrium in amniotes arose from a molecular blueprint present before the evolutionary emergence of cardiac septation and provide insights into the establishment of atrial asymmetry.
Asunto(s)
Corazón/embriología , Organogénesis , Pez Cebra/embriología , Animales , Tipificación del Cuerpo , Regulación del Desarrollo de la Expresión Génica , Proteínas de Homeodominio/biosíntesis , Proteínas de Pez Cebra/biosíntesisRESUMEN
The vertebrate embryo undergoes a series of dramatic morphological changes as the body extends to form the complete anterior-posterior axis during the somite-forming stages. The molecular mechanisms regulating these complex processes are still largely unknown. We show that the Hippo pathway transcriptional coactivators Yap1 and Wwtr1 are specifically localized to the presumptive epidermis and notochord, and play a critical and unexpected role in posterior body extension by regulating Fibronectin assembly underneath the presumptive epidermis and surrounding the notochord. We further find that Yap1 and Wwtr1, also via Fibronectin, have an essential role in the epidermal morphogenesis necessary to form the initial dorsal and ventral fins, a process previously thought to involve bending of an epithelial sheet, but which we now show involves concerted active cell movement. Our results reveal how the Hippo pathway transcriptional program, localized to two specific tissues, acts to control essential morphological events in the vertebrate embryo.
Asunto(s)
Epidermis/embriología , Regulación del Desarrollo de la Expresión Génica , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Morfogénesis , Notocorda/embriología , Transactivadores/metabolismo , Proteínas de Pez Cebra/metabolismo , Pez Cebra/embriología , Animales , Fibronectinas/metabolismo , Proteínas Coactivadoras Transcripcionales con Motivo de Unión a PDZ , Proteínas Señalizadoras YAPRESUMEN
Zebrafish display a distinct ability to regenerate their heart following injury. However, this ability is not shared by another teleost, the medaka. In order to identify cellular and molecular bases for this difference, we performed comparative transcriptomic analyses following cardiac cryoinjury. This comparison points to major differences in immune cell dynamics between these models. Upon closer examination, we observed delayed and reduced macrophage recruitment in medaka, along with delayed neutrophil clearance. To investigate the role of immune responses in cardiac regeneration, we delayed macrophage recruitment in zebrafish and observed compromised neovascularization, neutrophil clearance, cardiomyocyte proliferation and scar resolution. In contrast, stimulating Toll-like receptor signaling in medaka enhanced immune cell dynamics and promoted neovascularization, neutrophil clearance, cardiomyocyte proliferation and scar resolution. Altogether, these data provide further insight into the complex role of the immune response during regeneration, and serve as a platform to identify and test additional regulators of cardiac repair.
Asunto(s)
Lesiones Cardíacas/patología , Inmunidad Celular , Regeneración , Animales , Proliferación Celular , Perfilación de la Expresión Génica , Macrófagos/inmunología , Miocitos Cardíacos/fisiología , Neutrófilos/inmunología , Oryzias , Pez CebraRESUMEN
Vascular networks surrounding individual organs are important for their development, maintenance, and function; however, how these networks are assembled remains poorly understood. Here we show that CNS progenitors, referred to as radial glia, modulate vascular patterning around the spinal cord by acting as negative regulators. We found that radial glia ablation in zebrafish embryos leads to excessive sprouting of the trunk vessels around the spinal cord, and exclusively those of venous identity. Mechanistically, we determined that radial glia control this process via the Vegf decoy receptor sFlt1: sflt1 mutants exhibit the venous over-sprouting observed in radial glia-ablated larvae, and sFlt1 overexpression rescues it. Genetic mosaic analyses show that sFlt1 function in trunk endothelial cells can limit their over-sprouting. Together, our findings identify CNS-resident progenitors as critical angiogenic regulators that determine the precise patterning of the vasculature around the spinal cord, providing novel insights into vascular network formation around developing organs.