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1.
Development ; 148(4)2021 02 17.
Artículo en Inglés | MEDLINE | ID: mdl-33531430

RESUMEN

Hedgehog (Hh) ligands act as morphogens to direct patterning and proliferation during embryonic development. Protein kinase A (PKA) is a central negative regulator of Hh signalling, and in the absence of Hh ligands, PKA activity prevents inappropriate expression of Hh target genes. The orphan G-protein-coupled receptor Gpr161 contributes to the basal Hh repression machinery by activating PKA. Gpr161 acts as an A-kinase-anchoring protein, and is itself phosphorylated by PKA, but the functional significance of PKA phosphorylation of Gpr161 in the context of Hh signalling remains unknown. Here, we show that loss of Gpr161 in zebrafish leads to constitutive activation of medium and low, but not maximal, levels of Hh target gene expression. Furthermore, we find that PKA phosphorylation-deficient forms of Gpr161, which we show directly couple to Gαs, display an increased sensitivity to Shh, resulting in excess high-level Hh signalling. Our results suggest that PKA feedback-mediated phosphorylation of Gpr161 may provide a mechanism for fine-tuning Gpr161 ciliary localisation and PKA activity.


Asunto(s)
Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Retroalimentación Fisiológica , Proteínas Hedgehog/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transducción de Señal , Pez Cebra/fisiología , Animales , Evolución Biológica , Cilios/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/genética , Desarrollo Embrionario/genética , Proteínas Hedgehog/genética , Mutación , Fenotipo , Receptores Acoplados a Proteínas G/genética
2.
Proc Natl Acad Sci U S A ; 113(28): 7786-91, 2016 07 12.
Artículo en Inglés | MEDLINE | ID: mdl-27357676

RESUMEN

Scaffolding proteins organize the information flow from activated G protein-coupled receptors (GPCRs) to intracellular effector cascades both spatially and temporally. By this means, signaling scaffolds, such as A-kinase anchoring proteins (AKAPs), compartmentalize kinase activity and ensure substrate selectivity. Using a phosphoproteomics approach we identified a physical and functional connection between protein kinase A (PKA) and Gpr161 (an orphan GPCR) signaling. We show that Gpr161 functions as a selective high-affinity AKAP for type I PKA regulatory subunits (RI). Using cell-based reporters to map protein-protein interactions, we discovered that RI binds directly and selectively to a hydrophobic protein-protein interaction interface in the cytoplasmic carboxyl-terminal tail of Gpr161. Furthermore, our data demonstrate that a binary complex between Gpr161 and RI promotes the compartmentalization of Gpr161 to the plasma membrane. Moreover, we show that Gpr161, functioning as an AKAP, recruits PKA RI to primary cilia in zebrafish embryos. We also show that Gpr161 is a target of PKA phosphorylation, and that mutation of the PKA phosphorylation site affects ciliary receptor localization. Thus, we propose that Gpr161 is itself an AKAP and that the cAMP-sensing Gpr161:PKA complex acts as cilium-compartmentalized signalosome, a concept that now needs to be considered in the analyzing, interpreting, and pharmaceutical targeting of PKA-associated functions.


Asunto(s)
Proteínas de Anclaje a la Quinasa A/metabolismo , Proteína Quinasa Tipo I Dependiente de AMP Cíclico/metabolismo , AMP Cíclico/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Células HEK293 , Humanos , Luciferasas de Renilla , Ratones , Fosforilación , Pez Cebra
3.
Development ; 139(15): 2711-20, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22782722

RESUMEN

The Hedgehog (Hh) pathway plays dual roles in proliferation and patterning during embryonic development, but the mechanism(s) that distinguish the mitogenic and patterning activities of Hh signalling are not fully understood. An additional level of complexity is provided by the observation that Hh signalling can both promote and inhibit cell proliferation. One model to account for this apparent paradox is that Hh signalling primarily regulates cell cycle kinetics, such that activation of Hh signalling promotes fast cycling and an earlier cell cycle exit. Here we report that activation of Hh signalling promotes endodermal cell proliferation but inhibits proliferation in neighbouring non-endodermal cells, suggesting that the cell cycle kinetics model is insufficient to account for the opposing proliferative responses to Hh signalling. We show that expression of the chemokine receptor Cxcr4a is a critical parameter that determines the proliferative response to Hh signalling, and that loss of Cxcr4a function attenuates the transcription of cell cycle regulator targets of Hh signalling without affecting general transcriptional targets. We show that Cxcr4a inhibits PKA activity independently of Hh signalling, and propose that Cxcr4a enhances Hh-dependent proliferation by promoting the activity of Gli1. Our results indicate that Cxcr4a is required for Hh-dependent cell proliferation but not for Hh-dependent patterning, and suggest that the parallel activation of Cxcr4a is required to modulate the Hh pathway to distinguish between patterning and proliferation.


Asunto(s)
Endodermo/metabolismo , Receptores CXCR4/fisiología , Proteínas de Pez Cebra/fisiología , Alelos , Animales , Tipificación del Cuerpo , Proliferación Celular , Cruzamientos Genéticos , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Endodermo/citología , Proteínas Fluorescentes Verdes/metabolismo , Proteínas Hedgehog/metabolismo , Cinética , Ratones , Cresta Neural/citología , ARN Mensajero/metabolismo , Receptores CXCR4/metabolismo , Transducción de Señal , Transcripción Genética , Pez Cebra , Proteínas de Pez Cebra/metabolismo
4.
Nature ; 437(7061): 1018-21, 2005 Oct 13.
Artículo en Inglés | MEDLINE | ID: mdl-16136078

RESUMEN

The unanticipated involvement of several intraflagellar transport proteins in the mammalian Hedgehog (Hh) pathway has hinted at a functional connection between cilia and Hh signal transduction. Here we show that mammalian Smoothened (Smo), a seven-transmembrane protein essential for Hh signalling, is expressed on the primary cilium. This ciliary expression is regulated by Hh pathway activity; Sonic hedgehog or activating mutations in Smo promote ciliary localization, whereas the Smo antagonist cyclopamine inhibits ciliary localization. The translocation of Smo to primary cilia depends upon a conserved hydrophobic and basic residue sequence homologous to a domain previously shown to be required for the ciliary localization of seven-transmembrane proteins in Caenorhabditis elegans. Mutation of this domain not only prevents ciliary localization but also eliminates Smo activity both in cultured cells and in zebrafish embryos. Thus, Hh-dependent translocation to cilia is essential for Smo activity, suggesting that Smo acts at the primary cilium.


Asunto(s)
Cilios/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Vertebrados/metabolismo , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Caenorhabditis elegans/química , Línea Celular , Cilios/efectos de los fármacos , Perros , Proteínas de Drosophila/química , Embrión de Mamíferos/metabolismo , Embrión no Mamífero , Genes Reporteros/genética , Ratones , Mutación/genética , Señales de Clasificación de Proteína/genética , Señales de Clasificación de Proteína/fisiología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Receptores Acoplados a Proteínas G/química , Receptores Acoplados a Proteínas G/genética , Transducción de Señal , Receptor Smoothened , Alcaloides de Veratrum/farmacología , Vertebrados/embriología , Vertebrados/genética , Pez Cebra/embriología , Pez Cebra/genética , Pez Cebra/metabolismo
5.
Cells ; 9(1)2020 01 03.
Artículo en Inglés | MEDLINE | ID: mdl-31947770

RESUMEN

Compartmentalization of diverse types of signaling molecules contributes to the precise coordination of signal propagation. The primary cilium fulfills this function by acting as a spatiotemporally confined sensory signaling platform. For the integrity of ciliary signaling, it is mandatory that the ciliary signaling pathways are constantly attuned by alterations in both oscillating small molecules and the presence or absence of their sensor/effector proteins. In this context, ciliary G protein-coupled receptor (GPCR) pathways participate in coordinating the mobilization of the diffusible second messenger molecule 3',5'-cyclic adenosine monophosphate (cAMP). cAMP fluxes in the cilium are primarily sensed by protein kinase A (PKA) complexes, which are essential for the basal repression of Hedgehog (Hh) signaling. Here, we describe the dynamic properties of underlying signaling circuits, as well as strategies for second messenger compartmentalization. As an example, we summarize how receptor-guided cAMP-effector pathways control the off state of Hh signaling. We discuss the evidence that a macromolecular, ciliary-localized signaling complex, composed of the orphan GPCR Gpr161 and type I PKA holoenzymes, is involved in antagonizing Hh functions. Finally, we outline how ciliary cAMP-linked receptor pathways and cAMP-sensing signalosomes may become targets for more efficient combinatory therapy approaches to counteract dysregulation of Hh signaling.


Asunto(s)
Proteínas Hedgehog/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Cilios/metabolismo , AMP Cíclico/química , AMP Cíclico/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Humanos , Transducción de Señal
6.
Mech Dev ; 113(1): 99-102, 2002 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11900982

RESUMEN

Proteins of the Extramacrochaetae and Id subfamily of Helix-Loop-Helix (HLH) proteins are negative regulators of bHLH transcription factors. We cloned a cDNA from zebrafish which encodes a member of the id3 subfamily. High levels of transcripts accumulated in the germ ring and in the embryonic shield. Towards the end of gastrulation, Id3 was highly expressed in the anterior prechordal plate and hypoblast. At later stages, id3 expression was turned on and off in a large variety of tissues within short periods of time. These include the lateral mesoderm, the cornea, the lens, the brain, the neural crest, the retina and the fins.


Asunto(s)
Proteínas de Unión al ADN/biosíntesis , Embrión no Mamífero/metabolismo , Regulación del Desarrollo de la Expresión Génica , Proteínas de Neoplasias , Factores de Transcripción/biosíntesis , Secuencia de Aminoácidos , Animales , Northern Blotting , ADN Complementario/metabolismo , Proteínas de Unión al ADN/genética , Secuencias Hélice-Asa-Hélice , Inmunohistoquímica , Proteínas Inhibidoras de la Diferenciación , Datos de Secuencia Molecular , Filogenia , ARN Mensajero/metabolismo , Retina/embriología , Homología de Secuencia de Aminoácido , Factores de Tiempo , Distribución Tisular , Factores de Transcripción/genética , Pez Cebra
7.
Sci Rep ; 5: 11133, 2015 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-26099953

RESUMEN

Membrane receptor-sensed input signals affect and modulate intracellular protein-protein interactions (PPIs). Consequent changes occur to the compositions of protein complexes, protein localization and intermolecular binding affinities. Alterations of compartmentalized PPIs emanating from certain deregulated kinases are implicated in the manifestation of diseases such as cancer. Here we describe the application of a genetically encoded Protein-fragment Complementation Assay (PCA) based on the Renilla Luciferase (Rluc) enzyme to compare binary PPIs of the spatially and temporally controlled protein kinase A (PKA) network in diverse eukaryotic model systems. The simplicity and sensitivity of this cell-based reporter allows for real-time recordings of mutually exclusive PPIs of PKA upon activation of selected endogenous G protein-coupled receptors (GPCRs) in cancer cells, xenografts of mice, budding yeast, and zebrafish embryos. This extends the application spectrum of Rluc PCA for the quantification of PPI-based receptor-effector relationships in physiological and pathological model systems.


Asunto(s)
Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Mapeo de Interacción de Proteínas , Receptores Acoplados a Proteínas G/metabolismo , Animales , Técnicas Biosensibles , Línea Celular Tumoral , Embrión no Mamífero/metabolismo , Genes Reporteros , Células HEK293 , Humanos , Ratones , Osteosarcoma/metabolismo , Unión Proteica , Saccharomyces cerevisiae/metabolismo , Ensayos Antitumor por Modelo de Xenoinjerto , Pez Cebra/embriología , Pez Cebra/metabolismo
8.
BMC Bioinformatics ; 3: 29, 2002 Oct 22.
Artículo en Inglés | MEDLINE | ID: mdl-12390683

RESUMEN

BACKGROUND: Gene expression analyses based on complex hybridization measurements have increased rapidly in recent years and have given rise to a huge amount of bioinformatic tools such as image analyses and cluster analyses. However, the amount of work done to integrate and evaluate these tools and the corresponding experimental procedures is not high. Although complex hybridization experiments are based on a data production pipeline that incorporates a significant amount of error parameters, the evaluation of these parameters has not been studied yet in sufficient detail. RESULTS: In this paper we present simulation studies on several error parameters arising in complex hybridization experiments. A general tool was developed that allows the design of exactly defined hybridization data incorporating, for example, variations of spot shapes, spot positions and local and global background noise. The simulation environment was used to judge the influence of these parameters on subsequent data analysis, for example image analysis and the detection of differentially expressed genes. As a guide for simulating expression data real experimental data were used and model parameters were adapted to these data. Our results show how measurement error can be balanced by the analysis tools. CONCLUSIONS: We describe an implemented model for the simulation of DNA-array experiments. This tool was used to judge the influence of critical parameters on the subsequent image analysis and differential expression analysis. Furthermore the tool can be used to guide future experiments and to improve performance by better experimental design. Series of simulated images varying specific parameters can be downloaded from our web-site: http://www.molgen.mpg.de/~lh_bioinf/projects/simulation/biotech/


Asunto(s)
Simulación por Computador , Modelos Genéticos , Hibridación de Ácido Nucleico/métodos , Análisis de Secuencia por Matrices de Oligonucleótidos , Algoritmos , Arabidopsis/embriología , Arabidopsis/genética , Biología Computacional/métodos , Biología Computacional/estadística & datos numéricos , ADN Complementario/análisis , ADN de Plantas/análisis , Perfilación de la Expresión Génica/normas , Perfilación de la Expresión Génica/estadística & datos numéricos , Genoma de Planta , Análisis de Secuencia por Matrices de Oligonucleótidos/normas , Análisis de Secuencia por Matrices de Oligonucleótidos/estadística & datos numéricos , Proyectos de Investigación/normas , Proyectos de Investigación/estadística & datos numéricos
9.
Nat Commun ; 4: 2207, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23884240

RESUMEN

The ever-increasing speed and resolution of modern microscopes make the storage and post-processing of images challenging and prevent thorough statistical analyses in developmental biology. Here, instead of deploying massive storage and computing power, we exploit the spherical geometry of zebrafish embryos by computing a radial maximum intensity projection in real time with a 240-fold reduction in data rate. In our four-lens selective plane illumination microscope (SPIM) setup the development of multiple embryos is recorded in parallel and a map of all labelled cells is obtained for each embryo in <10 s. In these panoramic projections, cell segmentation and flow analysis reveal characteristic migration patterns and global tissue remodelling in the early endoderm. Merging data from many samples uncover stereotypic patterns that are fundamental to endoderm development in every embryo. We demonstrate that processing and compressing raw image data in real time is not only efficient but indispensable for image-based systems biology.


Asunto(s)
Endodermo/citología , Procesamiento de Imagen Asistido por Computador/instrumentación , Microscopía Fluorescente/instrumentación , Pez Cebra/anatomía & histología , Animales , Tipificación del Cuerpo , Diferenciación Celular , Movimiento Celular , Embrión no Mamífero , Endodermo/embriología , Procesamiento de Imagen Asistido por Computador/métodos , Luz , Microscopía Fluorescente/métodos , Pez Cebra/embriología
10.
Curr Biol ; 19(12): 1034-9, 2009 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-19464178

RESUMEN

Members of the Hedgehog (Hh) family of secreted proteins function as morphogens to pattern developing tissues and control cell proliferation. The seven-transmembrane domain (7TM) protein Smoothened (Smo) is essential for the activation of all levels of Hh signaling. However, the mechanisms by which Smo differentially activates low- or high-level Hh signaling are not known. Here we show that a newly identified mutation in the extracellular domain (ECD) of zebrafish Smo attenuates Smo signaling. The Smo agonist purmorphamine induces the stabilization, ciliary translocation, and high-level signaling of wild-type Smo. In contrast, purmorphamine induces the stabilization but not the ciliary translocation or high-level signaling of the Smo ECD mutant protein. Surprisingly, a truncated form of Smo that lacks the cysteine-rich domain of the ECD localizes to the cilium but is unable to activate high-level Hh signaling. We also present evidence that cilia may be required for Hh signaling in early zebrafish embryos. These data indicate that the ECD, previously thought to be dispensable for vertebrate Smo function, both regulates Smo ciliary localization and is essential for high-level Hh signaling.


Asunto(s)
Cilios , Proteínas Hedgehog/metabolismo , Receptores de Superficie Celular/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Transducción de Señal/fisiología , Proteínas de Pez Cebra/metabolismo , Secuencia de Aminoácidos , Animales , Cilios/fisiología , Cilios/ultraestructura , Proteínas Hedgehog/genética , Datos de Secuencia Molecular , Morfolinas/metabolismo , Estructura Terciaria de Proteína , Purinas/metabolismo , Receptores de Superficie Celular/genética , Receptores Acoplados a Proteínas G/genética , Receptor Smoothened , Pez Cebra/anatomía & histología , Pez Cebra/embriología , Pez Cebra/metabolismo , Proteínas de Pez Cebra/genética
11.
Dev Biol ; 304(2): 525-40, 2007 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-17306247

RESUMEN

Nodal signals induce mesodermal and endodermal progenitors during vertebrate development. To determine the role of Nodal signaling at a genomic level, we isolated Nodal-regulated genes by expression profiling using macroarrays and gene expression databases. Putative Nodal-regulated genes were validated by in situ hybridization screening in wild type and Nodal signaling mutants. 46 genes were identified, raising the currently known number of Nodal-regulated genes to 72. Based on their expression patterns along the dorsoventral axis, most of these genes can be classified into two groups. One group is expressed in the dorsal margin, whereas the other group is expressed throughout the margin. In addition to transcription factors and signaling components, the screens identified several new functional classes of Nodal-regulated genes, including cytoskeletal components and molecules involved in protein secretion or endoplasmic reticulum stress. We found that x-box binding protein-1 (xbp1) is a direct target of Nodal signaling and required for the terminal differentiation of the hatching gland, a specialized secretory organ whose specification is also dependent on Nodal signaling. These results indicate that Nodal signaling regulates not only specification genes but also differentiation genes.


Asunto(s)
Gástrula/metabolismo , Factor de Crecimiento Transformador beta/fisiología , Proteínas de Pez Cebra/fisiología , Pez Cebra/embriología , Animales , Diferenciación Celular , Proteínas de Unión al ADN/metabolismo , Regulación del Desarrollo de la Expresión Génica , Proteína Nodal , Análisis de Secuencia por Matrices de Oligonucleótidos , Factores de Transcripción del Factor Regulador X , Transducción de Señal , Factores de Transcripción/metabolismo , Pez Cebra/metabolismo , Proteínas de Pez Cebra/biosíntesis , Proteínas de Pez Cebra/genética
12.
Genome Res ; 14(2): 228-38, 2004 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-14718378

RESUMEN

Differential gene transcription is a fundamental regulatory mechanism of biological systems during development, body homeostasis, and disease. Comparative genomics is believed to be a rapid means for the identification of regulatory sequences in genomes. We tested this approach to identify regulatory sequences that control expression in the midline of the zebrafish embryo. We first isolated a set of genes that are coexpressed in the midline of the zebrafish embryo during somitogenesis stages by gene array analysis and subsequent rescreens by in situ hybridization. We subjected 45 of these genes to Compare and DotPlot analysis to detect conserved sequences in noncoding regions of orthologous loci in the zebrafish and Takifugu genomes. The regions of homology that were scored in nonconserved regions were inserted into expression vectors and tested for their regulatory activity by transient transgenesis in the zebrafish embryo. We identified one conserved region from the connective tissue growth factor gene (ctgf), which was able to drive expression in the midline of the embryo. This region shares sequence similarity with other floor plate/notochord-specific regulatory regions. Our results demonstrate that an unbiased comparative approach is a relevant method for the identification of tissue-specific cis-regulatory sequences in the zebrafish embryo.


Asunto(s)
Secuencia Conservada/genética , Perfilación de la Expresión Génica/métodos , Genómica/métodos , Regiones Promotoras Genéticas/genética , Pez Cebra/embriología , Animales , Animales Modificados Genéticamente , Secuencia de Bases , Factor de Crecimiento del Tejido Conjuntivo , Sondas de ADN/genética , Embrión no Mamífero/química , Embrión no Mamífero/citología , Embrión no Mamífero/metabolismo , Elementos de Facilitación Genéticos/genética , Regulación del Desarrollo de la Expresión Génica/genética , Proteínas Inmediatas-Precoces/genética , Hibridación in Situ/métodos , Péptidos y Proteínas de Señalización Intercelular/genética , Datos de Secuencia Molecular , Notocorda/química , Notocorda/citología , Notocorda/metabolismo , Análisis de Secuencia de ADN/métodos , Homología de Secuencia de Ácido Nucleico , Proteínas de Pez Cebra/genética
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