RESUMEN
Hematopoietic stem and progenitor cells (HSPCs) can reconstitute and sustain the entire blood system. We generated a highly specific transgenic reporter of HSPCs in zebrafish. This allowed us to perform high-resolution live imaging on endogenous HSPCs not currently possible in mammalian bone marrow. Using this system, we have uncovered distinct interactions between single HSPCs and their niche. When an HSPC arrives in the perivascular niche, a group of endothelial cells remodel to form a surrounding pocket. This structure appears conserved in mouse fetal liver. Correlative light and electron microscopy revealed that endothelial cells surround a single HSPC attached to a single mesenchymal stromal cell. Live imaging showed that mesenchymal stromal cells anchor HSPCs and orient their divisions. A chemical genetic screen found that the compound lycorine promotes HSPC-niche interactions during development and ultimately expands the stem cell pool into adulthood. Our studies provide evidence for dynamic niche interactions upon stem cell colonization. PAPERFLICK:
Asunto(s)
Endotelio/fisiología , Células Madre Hematopoyéticas/citología , Pez Cebra/embriología , Animales , Animales Modificados Genéticamente , División Celular , Subunidades alfa del Factor de Unión al Sitio Principal/genética , Subunidades alfa del Factor de Unión al Sitio Principal/metabolismo , Embrión no Mamífero/irrigación sanguínea , Embrión no Mamífero/fisiología , Endotelio/citología , Células Madre Hematopoyéticas/fisiología , Mesodermo/citología , Mesodermo/metabolismo , Ratones , Ratones Endogámicos C57BL , Nicho de Células Madre , Células del Estroma/citología , Células del Estroma/metabolismo , Pez Cebra/fisiologíaRESUMEN
Haematopoietic stem and progenitor cells (HSPCs) require a specific microenvironment, the haematopoietic niche, which regulates HSPC behaviour1,2. The location of this niche varies across species, but the evolutionary pressures that drive HSPCs to different microenvironments remain unknown. The niche is located in the bone marrow in adult mammals, whereas it is found in other locations in non-mammalian vertebrates, for example, in the kidney marrow in teleost fish. Here we show that a melanocyte umbrella above the kidney marrow protects HSPCs against ultraviolet light in zebrafish. Because mutants that lack melanocytes have normal steady-state haematopoiesis under standard laboratory conditions, we hypothesized that melanocytes above the stem cell niche protect HSPCs against ultraviolet-light-induced DNA damage. Indeed, after ultraviolet-light irradiation, unpigmented larvae show higher levels of DNA damage in HSPCs, as indicated by staining of cyclobutane pyrimidine dimers and have reduced numbers of HSPCs, as shown by cmyb (also known as myb) expression. The umbrella of melanocytes associated with the haematopoietic niche is highly evolutionarily conserved in aquatic animals, including the sea lamprey, a basal vertebrate. During the transition from an aquatic to a terrestrial environment, HSPCs relocated into the bone marrow, which is protected from ultraviolet light by the cortical bone around the marrow. Our studies reveal that melanocytes above the haematopoietic niche protect HSPCs from ultraviolet-light-induced DNA damage in aquatic vertebrates and suggest that during the transition to terrestrial life, ultraviolet light was an evolutionary pressure affecting the location of the haematopoietic niche.
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Evolución Biológica , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/efectos de la radiación , Melanocitos/citología , Melanocitos/efectos de la radiación , Nicho de Células Madre/efectos de la radiación , Rayos Ultravioleta/efectos adversos , Animales , Organismos Acuáticos/clasificación , Citoprotección/efectos de la radiación , Daño del ADN/efectos de la radiación , Riñón , Mutación , Petromyzon/clasificación , Filogenia , Dímeros de Pirimidina/efectos de la radiación , Nicho de Células Madre/fisiología , Pez Cebra/clasificación , Pez Cebra/genéticaRESUMEN
Studying cancer metabolism gives insight into tumorigenic survival mechanisms and susceptibilities. In melanoma, we identify HEXIM1, a transcription elongation regulator, as a melanoma tumor suppressor that responds to nucleotide stress. HEXIM1 expression is low in melanoma. Its overexpression in a zebrafish melanoma model suppresses cancer formation, while its inactivation accelerates tumor onset in vivo. Knockdown of HEXIM1 rescues zebrafish neural crest defects and human melanoma proliferation defects that arise from nucleotide depletion. Under nucleotide stress, HEXIM1 is induced to form an inhibitory complex with P-TEFb, the kinase that initiates transcription elongation, to inhibit elongation at tumorigenic genes. The resulting alteration in gene expression also causes anti-tumorigenic RNAs to bind to and be stabilized by HEXIM1. HEXIM1 plays an important role in inhibiting cancer cell-specific gene transcription while also facilitating anti-cancer gene expression. Our study reveals an important role for HEXIM1 in coupling nucleotide metabolism with transcriptional regulation in melanoma.
Asunto(s)
Melanoma/metabolismo , Factor B de Elongación Transcripcional Positiva/genética , Pirimidinas/metabolismo , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Animales , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Humanos , Melanoma/genética , Melanoma/patología , Melanoma Experimental , Proteínas Oncogénicas/genética , Factores de Transcripción , Transcripción Genética , Proteínas Supresoras de Tumor/genética , Pez Cebra/genética , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/metabolismoRESUMEN
Invadopodia are specialized membrane protrusions composed of F-actin, actin regulators, signaling proteins, and a dynamically trafficked invadopodial membrane that drive cell invasion through basement membrane (BM) barriers in development and cancer. Due to the challenges of studying invasion in vivo, mechanisms controlling invadopodia formation in their native environments remain poorly understood. We performed a sensitized genome-wide RNAi screen and identified 13 potential regulators of invadopodia during anchor cell (AC) invasion into the vulval epithelium in C. elegans. Confirming the specificity of this screen, we identified the Rho GTPase cdc-42, which mediates invadopodia formation in many cancer cell lines. Using live-cell imaging, we show that CDC-42 localizes to the AC-BM interface and is activated by an unidentified vulval signal(s) that induces invasion. CDC-42 is required for the invasive membrane localization of WSP-1 (N-WASP), a CDC-42 effector that promotes polymerization of F-actin. Loss of CDC-42 or WSP-1 resulted in fewer invadopodia and delayed BM breaching. We also characterized a novel invadopodia regulator, gdi-1 (Rab GDP dissociation inhibitor), which mediates membrane trafficking. We show that GDI-1 functions in the AC to promote invadopodia formation. In the absence of GDI-1, the specialized invadopodial membrane was no longer trafficked normally to the invasive membrane, and instead was distributed to plasma membrane throughout the cell. Surprisingly, the pro-invasive signal(s) from the vulval cells also controls GDI-1 activity and invadopodial membrane trafficking. These studies represent the first in vivo screen for genes regulating invadopodia and demonstrate that invadopodia formation requires the integration of distinct cellular processes that are coordinated by an extracellular cue.
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Proteínas de Caenorhabditis elegans/genética , Proteínas de Ciclo Celular/genética , Proteínas de Unión al GTP/genética , Inhibidores de Disociación de Guanina Nucleótido/genética , Neoplasias/genética , Podosomas/genética , Animales , Membrana Basal/crecimiento & desarrollo , Caenorhabditis elegans/genética , Caenorhabditis elegans/crecimiento & desarrollo , Proteínas de Caenorhabditis elegans/biosíntesis , Proteínas de Ciclo Celular/biosíntesis , Modelos Animales de Enfermedad , Matriz Extracelular/genética , Proteínas de Unión al GTP/biosíntesis , Regulación del Desarrollo de la Expresión Génica , Inhibidores de Disociación de Guanina Nucleótido/biosíntesis , Humanos , Neoplasias/patología , Podosomas/patología , Transducción de SeñalRESUMEN
Rare endothelial cells in the aorta-gonad-mesonephros (AGM) transition into hematopoietic stem cells (HSCs) during embryonic development. Lineage tracing experiments indicate that HSCs emerge from cadherin 5 (Cdh5; vascular endothelial-cadherin)(+) endothelial precursors, and isolated populations of Cdh5(+) cells from mouse embryos and embryonic stem cells can be differentiated into hematopoietic cells. Cdh5 has also been widely implicated as a marker of AGM-derived hemogenic endothelial cells. Because Cdh5(-/-) mice embryos die before the first HSCs emerge, it is unknown whether Cdh5 has a direct role in HSC emergence. Our previous genetic screen yielded malbec (mlb(bw306)), a zebrafish mutant for cdh5, with normal embryonic and definitive blood. Using time-lapse confocal imaging, parabiotic surgical pairing of zebrafish embryos, and blastula transplantation assays, we show that HSCs emerge, migrate, engraft, and differentiate in the absence of cdh5 expression. By tracing Cdh5(-/-)green fluorescent protein (GFP)(+/+) cells in chimeric mice, we demonstrated that Cdh5(-/-)GFP(+/+) HSCs emerging from embryonic day 10.5 and 11.5 (E10.5 and E11.5) AGM or derived from E13.5 fetal liver not only differentiate into hematopoietic colonies but also engraft and reconstitute multilineage adult blood. We also developed a conditional mouse Cdh5 knockout (Cdh5(flox/flox):Scl-Cre-ER(T)) and demonstrated that multipotent hematopoietic colonies form despite the absence of Cdh5. These data establish that Cdh5, a marker of hemogenic endothelium in the AGM, is dispensable for the transition of hemogenic endothelium to HSCs.
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Antígenos CD/metabolismo , Cadherinas/metabolismo , Diferenciación Celular/fisiología , Hemangioblastos/citología , Hematopoyesis/fisiología , Células Madre Hematopoyéticas/citología , Animales , Linaje de la Célula/fisiología , Electroporación , Embrión de Mamíferos , Embrión no Mamífero , Citometría de Flujo , Inmunohistoquímica , Mesonefro/embriología , Ratones , Ratones Noqueados , Microscopía Confocal , Pez CebraRESUMEN
Throughout the lifetime of an individual, hematopoietic stem cells (HSCs) self-renew and differentiate into lineages that include erythrocytes, platelets and all immune cells. HSC transplantation offers a potentially curative treatment for a number of hematopoietic and non-hematopoietic malignancies as well as immune and genetic disorders. Limited availability of immune-matched donors reduces the viable options for many patients in need of HSC transplantation, particularly those of diverse racial and ethnic backgrounds. Due to rapid availability and less stringent immune-matching requirements, umbilical cord blood (UCB) has emerged as a valuable source of transplantable HSCs. A single UCB unit contains a suboptimal number of HSCs for treating larger children or adults and there has thus been great clinical interest in expanding UCB HSCs ex vivo for use in transplantation. In this review we discuss the latest research and future avenues for the therapeutic use of small lipid mediator dmPGE2 to expand HSC numbers for transplantation. Originally identified in a chemical screen in zebrafish, dmPGE2 has now advanced to a phase II clinical trial as a therapy for patients with leukemia and lymphoma who are undergoing UCB transplantation.
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Médula Ósea/metabolismo , Dinoprostona/farmacología , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/efectos de los fármacos , Adulto , Animales , Sangre Fetal/citología , Sangre Fetal/efectos de los fármacos , HumanosRESUMEN
Altered hematopoietic stem cell (HSC) fate underlies primary blood disorders but microenvironmental factors controlling this are poorly understood. Genetically barcoded genome editing of synthetic target arrays for lineage tracing (GESTALT) zebrafish were used to screen for factors expressed by the sinusoidal vascular niche that alter the phylogenetic distribution of the HSC pool under native conditions. Dysregulated expression of protein kinase C delta (PKC-δ, encoded by prkcda) increases the number of HSC clones by up to 80% and expands polyclonal populations of immature neutrophil and erythroid precursors. PKC agonists such as cxcl8 augment HSC competition for residency within the niche and expand defined niche populations. CXCL8 induces association of PKC-δ with the focal adhesion complex, activating extracellular signal-regulated kinase (ERK) signaling and expression of niche factors in human endothelial cells. Our findings demonstrate the existence of reserve capacity within the niche that is controlled by CXCL8 and PKC and has significant impact on HSC phylogenetic and phenotypic fate.
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Células Endoteliales , Pez Cebra , Animales , Humanos , Células Endoteliales/metabolismo , Hematopoyesis/genética , Células Madre Hematopoyéticas/metabolismo , Filogenia , Proteína Quinasa C-delta/metabolismo , Nicho de Células Madre , Interleucina-8/metabolismoRESUMEN
The hematopoietic niche is a supportive microenvironment composed of distinct cell types, including specialized vascular endothelial cells that directly interact with hematopoietic stem and progenitor cells (HSPCs). The molecular factors that specify niche endothelial cells and orchestrate HSPC homeostasis remain largely unknown. Using multi-dimensional gene expression and chromatin accessibility analyses in zebrafish, we define a conserved gene expression signature and cis-regulatory landscape that are unique to sinusoidal endothelial cells in the HSPC niche. Using enhancer mutagenesis and transcription factor overexpression, we elucidate a transcriptional code that involves members of the Ets, Sox, and nuclear hormone receptor families and is sufficient to induce ectopic niche endothelial cells that associate with mesenchymal stromal cells and support the recruitment, maintenance, and division of HSPCs in vivo. These studies set forth an approach for generating synthetic HSPC niches, in vitro or in vivo, and for effective therapies to modulate the endogenous niche.
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Nicho de Células Madre , Factores de Transcripción , Animales , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Células Endoteliales/metabolismo , Pez Cebra/genética , Pez Cebra/metabolismo , Regulación de la Expresión GénicaRESUMEN
Tissue-specific stem cells persist for a lifetime and can differentiate to maintain homeostasis or transform to initiate cancer. Despite their importance, there are no described quality assurance mechanisms for newly formed stem cells. We observed intimate and specific interactions between macrophages and nascent blood stem cells in zebrafish embryos. Macrophage interactions frequently led to either removal of cytoplasmic material and stem cell division or complete engulfment and stem cell death. Stressed stem cells were marked by surface Calreticulin, which stimulated macrophage interactions. Using cellular barcoding, we found that Calreticulin knock-down or embryonic macrophage depletion reduced the number of stem cell clones that established adult hematopoiesis. Our work supports a model in which embryonic macrophages determine hematopoietic clonality by monitoring stem cell quality.
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Apoptosis , Calreticulina , Comunicación Celular , Hematopoyesis Clonal , Células Madre Hematopoyéticas , Macrófagos , Animales , Calbindina 2/genética , Calbindina 2/fisiología , Calreticulina/genética , Calreticulina/metabolismo , Hematopoyesis Clonal/genética , Hematopoyesis Clonal/fisiología , Embrión no Mamífero , Células Madre Hematopoyéticas/fisiología , Macrófagos/fisiología , Pez Cebra , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/fisiologíaRESUMEN
We have isolated mutations in the Drosophila melanogaster homologue of auxilin, a J-domain-containing protein known to cooperate with Hsc70 in the disassembly of clathrin coats from clathrin-coated vesicles in vitro. Consistent with this biochemical role, animals with reduced auxilin function exhibit genetic interactions with Hsc70 and clathrin. Interestingly, the auxilin mutations interact specifically with Notch and disrupt several Notch-mediated processes. Genetic evidence places auxilin function in the signal-sending cells, upstream of Notch receptor activation, suggesting that the relevant cargo for this auxilin-mediated endocytosis is the Notch ligand Delta. Indeed, the localization of Delta protein is disrupted in auxilin mutant tissues. Thus, our data suggest that auxilin is an integral component of the Notch signaling pathway, participating in the ubiquitin-dependent endocytosis of Delta. Furthermore, the fact that auxilin is required for Notch signaling suggests that ligand endocytosis in the signal-sending cells needs to proceed past coat disassembly to activate Notch.
Asunto(s)
Auxilinas/fisiología , Drosophila melanogaster/fisiología , Proteínas de la Membrana/metabolismo , Receptores Notch/fisiología , Transducción de Señal/fisiología , Animales , Auxilinas/genética , Tipificación del Cuerpo/genética , Tipificación del Cuerpo/fisiología , Clatrina/genética , Clatrina/metabolismo , Drosophila melanogaster/embriología , Drosophila melanogaster/genética , Endocitosis/genética , Endocitosis/fisiología , Receptores ErbB/genética , Receptores ErbB/fisiología , Anomalías del Ojo/genética , Anomalías del Ojo/ultraestructura , Regulación del Desarrollo de la Expresión Génica , Genotipo , Proteínas del Choque Térmico HSC70/genética , Proteínas del Choque Térmico HSC70/metabolismo , Péptidos y Proteínas de Señalización Intracelular , Proteínas de la Membrana/genética , Microscopía Electrónica de Rastreo , Mutación/genética , Sistema Nervioso/embriología , Sistema Nervioso/metabolismo , Fenotipo , Células Fotorreceptoras de Invertebrados/embriología , Células Fotorreceptoras de Invertebrados/metabolismo , ARN Interferente Pequeño/genética , Receptores Notch/genética , Transducción de Señal/genética , Alas de Animales/embriología , Alas de Animales/metabolismo , Alas de Animales/ultraestructuraRESUMEN
Transcription and metabolism both influence cell function, but dedicated transcriptional control of metabolic pathways that regulate cell fate has rarely been defined. We discovered, using a chemical suppressor screen, that inhibition of the pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase (DHODH) rescues erythroid differentiation in bloodless zebrafish moonshine (mon) mutant embryos defective for transcriptional intermediary factor 1 gamma (tif1γ). This rescue depends on the functional link of DHODH to mitochondrial respiration. The transcription elongation factor TIF1γ directly controls coenzyme Q (CoQ) synthesis gene expression. Upon tif1γ loss, CoQ levels are reduced, and a high succinate/α-ketoglutarate ratio leads to increased histone methylation. A CoQ analog rescues mon's bloodless phenotype. These results demonstrate that mitochondrial metabolism is a key output of a lineage transcription factor that drives cell fate decisions in the early blood lineage.
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Eritropoyesis , Mitocondrias/metabolismo , Factores de Transcripción/metabolismo , Transcripción Genética , Proteínas de Pez Cebra/metabolismo , Animales , Ciclo del Ácido Cítrico , Metilación de ADN , Dihidroorotato Deshidrogenasa , Transporte de Electrón , Embrión no Mamífero/metabolismo , Inhibidores Enzimáticos/farmacología , Regulación de la Expresión Génica , Histonas/metabolismo , Leflunamida/farmacología , Redes y Vías Metabólicas , Metilación , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/antagonistas & inhibidores , Consumo de Oxígeno , Factores de Transcripción/genética , Ubiquinona/metabolismo , Pez Cebra/embriología , Pez Cebra/genética , Proteínas de Pez Cebra/genéticaRESUMEN
The restrictive nature of the blood-brain barrier (BBB) creates a major challenge for brain drug delivery with current nanomedicines lacking the ability to cross the BBB. Extracellular vesicles (EVs) have been shown to contribute to the progression of a variety of brain diseases including metastatic brain cancer and have been suggested as promising therapeutics and drug delivery vehicles. However, the ability of native tumor-derived EVs to breach the BBB and the mechanism(s) involved in this process remain unknown. Here, we demonstrate that tumor-derived EVs can breach the intact BBB in vivo, and by using state-of-the-art in vitro and in vivo models of the BBB, we have identified transcytosis as the mechanism underlying this process. Moreover, high spatiotemporal resolution microscopy demonstrated that the endothelial recycling endocytic pathway is involved in this transcellular transport. We further identify and characterize the mechanism by which tumor-derived EVs circumvent the low physiologic rate of transcytosis in the BBB by decreasing the brain endothelial expression of rab7 and increasing the efficiency of their transport. These findings identify previously unknown mechanisms by which tumor-derived EVs breach an intact BBB during the course of brain metastasis and can be leveraged to guide and inform the development of drug delivery approaches to deliver therapeutic cargoes across the BBB for treatment of a variety of brain diseases including, but not limited to, brain malignancies.
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Barrera Hematoencefálica/metabolismo , Neoplasias de la Mama/metabolismo , Vesículas Extracelulares/metabolismo , Transcitosis , Animales , Neoplasias Encefálicas/secundario , Caveolinas/metabolismo , Línea Celular Tumoral , Regulación hacia Abajo , Endosomas/metabolismo , Endotelio/metabolismo , Vesículas Extracelulares/ultraestructura , Femenino , Humanos , Ratones Desnudos , Transporte de Proteínas , Proteínas SNARE/metabolismo , Proteínas de Unión al GTP rab/metabolismo , Proteínas de Unión a GTP rab7RESUMEN
Xenografts of the hematopoietic system are extremely useful as disease models and for translational research. Zebrafish xenografts have been widely used to monitor blood cancer cell dissemination and homing due to the optical clarity of embryos and larvae, which allow unrestricted in vivo visualization of migratory events. Here, we have developed a xenotransplantation technique that transiently generates hundreds of hematopoietic tissue chimeric embryos by transplanting murine bone marrow cells into zebrafish blastulae. In contrast to previous methods, this procedure allows mammalian cell integration into the fish developmental hematopoietic program, which results in chimeric animals containing distinct phenotypes of murine blood cells in both circulation and the hematopoietic niche. Murine cells in chimeric animals express antigens related to (i) hematopoietic stem and progenitor cells, (ii) active cell proliferation and (iii) myeloid cell lineages. We verified the utility of this method by monitoring zebrafish chimeras during development using in vivo non-invasive imaging to show novel murine cell behaviors, such as homing to primitive and definitive hematopoietic tissues, dynamic hematopoietic cell and hematopoietic niche interactions, and response to bacterial infection. Overall, transplantation into the zebrafish blastula provides a useful method that simplifies the generation of numerous chimeric animals and expands the range of murine cell behaviors that can be studied in zebrafish chimeras. In addition, integration of murine cells into the host hematopoietic system during development suggests highly conserved molecular mechanisms of hematopoiesis between zebrafish and mammals.This article has an associated First Person interview with the first author of the paper.
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Quimera/embriología , Embrión de Mamíferos/fisiología , Embrión no Mamífero/fisiología , Hematopoyesis , Interacciones Huésped-Patógeno , Pez Cebra/embriología , Animales , Infecciones Bacterianas/patología , Blástula/trasplante , Células de la Médula Ósea/citología , Trasplante de Médula Ósea , Fusión Celular , Linaje de la Célula , Movimiento Celular , Rastreo Celular , Colorantes/metabolismo , Femenino , Larva/citología , Masculino , Ratones Endogámicos C57BL , Células Mieloides/citología , Trasplante Heterólogo , Pez Cebra/microbiologíaRESUMEN
Cell invasion through basement membrane (BM) barriers is crucial in development, leukocyte trafficking and the spread of cancer. The mechanisms that direct invasion, despite their importance in normal and disease states, are poorly understood, largely because of the inability to visualize dynamic cell-BM interactions in vivo. This protocol describes multichannel time-lapse confocal imaging of anchor-cell invasion in live Caenorhabditis elegans. Methods presented include outline-slide preparation and worm growth synchronization (15 min), mounting (20 min), image acquisition (20-180 min), image processing (20 min) and quantitative analysis (variable timing). The acquired images enable direct measurement of invasive dynamics including formation of invadopodia and cell-membrane protrusions, and removal of BM. This protocol can be combined with genetic analysis, molecular-activity probes and optogenetic approaches to uncover the molecular mechanisms underlying cell invasion. These methods can also be readily adapted by any worm laboratory for real-time analysis of cell migration, BM turnover and cell-membrane dynamics.
Asunto(s)
Membrana Basal/diagnóstico por imagen , Membrana Basal/metabolismo , Caenorhabditis elegans/citología , Imagenología Tridimensional/métodos , Microscopía Confocal/métodos , Imagen de Lapso de Tiempo/métodos , Animales , Membrana Celular/metabolismoRESUMEN
Hematopoietic stem/progenitor cells (HSPCs) are formed during ontogeny from hemogenic endothelium in the ventral wall of the dorsal aorta (VDA). Critically, the cellular mechanism(s) allowing HSPC egress and migration to secondary niches are incompletely understood. Matrix metalloproteinases (MMPs) are inflammation-responsive proteins that regulate extracellular matrix (ECM) remodeling, cellular interactions, and signaling. Here, inhibition of vascular-associated Mmp2 function caused accumulation of fibronectin-rich ECM, retention of runx1/cmyb+ HSPCs in the VDA, and delayed caudal hematopoietic tissue (CHT) colonization; these defects were absent in fibronectin mutants, indicating that Mmp2 facilitates endothelial-to-hematopoietic transition via ECM remodeling. In contrast, Mmp9 was dispensable for HSPC budding, being instead required for proper colonization of secondary niches. Significantly, these migration defects were mimicked by overexpression and blocked by knockdown of C-X-C motif chemokine-12 (cxcl12), suggesting that Mmp9 controls CHT homeostasis through chemokine regulation. Our findings indicate Mmp2 and Mmp9 play distinct but complementary roles in developmental HSPC production and migration.
Asunto(s)
Movimiento Celular , Células Madre Embrionarias/citología , Células Madre Hematopoyéticas/citología , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Nicho de Células Madre , Animales , Proliferación Celular , Quimiocina CXCL12/metabolismo , Subunidad alfa 2 del Factor de Unión al Sitio Principal/metabolismo , Células Madre Embrionarias/metabolismo , Células Madre Embrionarias/fisiología , Matriz Extracelular/metabolismo , Fibronectinas/metabolismo , Células Madre Hematopoyéticas/metabolismo , Células Madre Hematopoyéticas/fisiología , Metaloproteinasa 2 de la Matriz/genética , Metaloproteinasa 9 de la Matriz/genética , Pez Cebra/embriología , Pez Cebra/metabolismo , Proteínas de Pez Cebra/metabolismoRESUMEN
The microenvironment is an important regulator of hematopoietic stem and progenitor cell (HSPC) biology. Recent advances marking fluorescent HSPCs have allowed exquisite visualization of HSPCs in the caudal hematopoietic tissue (CHT) of the developing zebrafish. Here, we show that the chemokine cxcl8 and its receptor, cxcr1, are expressed by zebrafish endothelial cells, and we identify cxcl8/cxcr1 signaling as a positive regulator of HSPC colonization. Single-cell tracking experiments demonstrated that this is a result of increases in HSPC-endothelial cell "cuddling," HSPC residency time within the CHT, and HSPC mitotic rate. Enhanced cxcl8/cxcr1 signaling was associated with an increase in the volume of the CHT and induction of cxcl12a expression. Finally, using parabiotic zebrafish, we show that cxcr1 acts HSPC nonautonomously to improve the efficiency of donor HSPC engraftment. This work identifies a mechanism by which the hematopoietic niche remodels to promote HSPC engraftment and suggests that cxcl8/cxcr1 signaling is a potential therapeutic target in patients undergoing hematopoietic stem cell transplantation.
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Trasplante de Células Madre Hematopoyéticas , Receptores de Interleucina-8A/fisiología , Animales , Células Cultivadas , Microambiente Celular , Células Madre Hematopoyéticas/fisiología , Interleucina-8/fisiología , Transducción de Señal/fisiología , Pez CebraRESUMEN
We studied three patients with severe skeletal dysplasia, T cell immunodeficiency, and developmental delay. Whole-exome sequencing revealed homozygous missense mutations affecting exostosin-like 3 (EXTL3), a glycosyltransferase involved in heparan sulfate (HS) biosynthesis. Patient-derived fibroblasts showed abnormal HS composition and altered fibroblast growth factor 2 signaling, which was rescued by overexpression of wild-type EXTL3 cDNA. Interleukin-2-mediated STAT5 phosphorylation in patients' lymphocytes was markedly reduced. Interbreeding of the extl3-mutant zebrafish (box) with Tg(rag2:green fluorescent protein) transgenic zebrafish revealed defective thymopoiesis, which was rescued by injection of wild-type human EXTL3 RNA. Targeted differentiation of patient-derived induced pluripotent stem cells showed a reduced expansion of lymphohematopoietic progenitor cells and defects of thymic epithelial progenitor cell differentiation. These data identify EXTL3 mutations as a novel cause of severe immune deficiency with skeletal dysplasia and developmental delay and underline a crucial role of HS in thymopoiesis and skeletal and brain development.
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Enfermedades del Desarrollo Óseo/etiología , Discapacidades del Desarrollo/etiología , Síndromes de Inmunodeficiencia/etiología , Mutación , N-Acetilglucosaminiltransferasas/genética , Animales , Preescolar , Femenino , Heparitina Sulfato/fisiología , Humanos , Células Madre Pluripotentes Inducidas/citología , Lactante , Linfocitos/fisiología , Pez CebraRESUMEN
Surgical parabiosis of two animals of different genetic backgrounds creates a unique scenario to study cell-intrinsic versus cell-extrinsic roles for candidate genes of interest, migratory behaviors of cells, and secreted signals in distinct genetic settings. Because parabiotic animals share a common circulation, any blood or blood-borne factor from one animal will be exchanged with its partner and vice versa. Thus, cells and molecular factors derived from one genetic background can be studied in the context of a second genetic background. Parabiosis of adult mice has been used extensively to research aging, cancer, diabetes, obesity, and brain development. More recently, parabiosis of zebrafish embryos has been used to study the developmental biology of hematopoiesis. In contrast to mice, the transparent nature of zebrafish embryos permits the direct visualization of cells in the parabiotic context, making it a uniquely powerful method for investigating fundamental cellular and molecular mechanisms. The utility of this technique, however, is limited by a steep learning curve for generating the parabiotic zebrafish embryos. This protocol provides a step-by-step method on how to surgically fuse the blastulae of two zebrafish embryos of different genetic backgrounds to investigate the role of candidate genes of interest. In addition, the parabiotic zebrafish embryos are tolerant to heat shock, making temporal control of gene expression possible. This method does not require a sophisticated set-up and has broad applications for studying cell migration, fate specification, and differentiation in vivo during embryonic development.
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Blástula , Animales , Movimiento Celular , Hematopoyesis , Ratones , Parabiosis , Pez CebraRESUMEN
The "cancerized field" concept posits that cancer-prone cells in a given tissue share an oncogenic mutation, but only discreet clones within the field initiate tumors. Most benign nevi carry oncogenic BRAF(V600E) mutations but rarely become melanoma. The zebrafish crestin gene is expressed embryonically in neural crest progenitors (NCPs) and specifically reexpressed in melanoma. Live imaging of transgenic zebrafish crestin reporters shows that within a cancerized field (BRAF(V600E)-mutant; p53-deficient), a single melanocyte reactivates the NCP state, revealing a fate change at melanoma initiation in this model. NCP transcription factors, including sox10, regulate crestin expression. Forced sox10 overexpression in melanocytes accelerated melanoma formation, which is consistent with activation of NCP genes and super-enhancers leading to melanoma. Our work highlights NCP state reemergence as a key event in melanoma initiation.
Asunto(s)
Carcinogénesis/genética , Regulación del Desarrollo de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Melanoma Experimental/genética , Melanoma/genética , Cresta Neural/metabolismo , Neoplasias Cutáneas/genética , Pez Cebra , Animales , Animales Modificados Genéticamente , Células Madre Embrionarias/metabolismo , Elementos de Facilitación Genéticos , Genes Reporteros , Proteínas Fluorescentes Verdes/genética , Melanocitos/metabolismo , Mutación , Proteínas del Tejido Nervioso/genética , Proteínas Proto-Oncogénicas B-raf/genética , Factores de Transcripción SOXE/genética , Proteína p53 Supresora de Tumor/genética , Proteínas de Pez Cebra/genéticaRESUMEN
Angiopoietin-like proteins (angptls) are capable of ex vivo expansion of mouse and human hematopoietic stem and progenitor cells (HSPCs). Despite this intriguing ability, their mechanism is unknown. In this study, we show that angptl2 overexpression is sufficient to expand definitive HSPCs in zebrafish embryos. Angptl1/2 are required for definitive hematopoiesis and vascular specification of the hemogenic endothelium. The loss-of-function phenotype is reminiscent of the notch mutant mindbomb (mib), and a strong genetic interaction occurs between angptls and notch. Overexpressing angptl2 rescues mib while overexpressing notch rescues angptl1/2 morphants. Gene expression studies in ANGPTL2-stimulated CD34(+) cells showed a strong MYC activation signature and myc overexpression in angptl1/2 morphants or mib restored HSPCs formation. ANGPTL2 can increase NOTCH activation in cultured cells and ANGPTL receptor interacted with NOTCH to regulate NOTCH cleavage. Together our data provide insight to the angptl-mediated notch activation through receptor interaction and subsequent activation of myc targets.