Los autores agradecen a Christa Haase, Doris Weber y Brigitte Korte para la asistencia técnica. El trabajo en el laboratorio Weidinger el apoyo de subvenciones de la Deutsche Forschungsgemeinschaft WE 4223 / 3-1, WE 4223 / 4-1 y por la Deutsche Gesellschaft für Kardiologie través de un Oskar-Lapp-Stipendium y Klaus-Georg-und-Sigrid- Hengstberger-Forschungsstipendium.

<ol>
	<li>Fang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Translational+profiling+of+cardiomyocytes+identifies+an+early+Jak1/Stat3+injury+response+required+for+zebrafish+heart+regeneration.">Translational profiling of cardiomyocytes identifies an early Jak1/Stat3 injury response required for zebrafish heart regeneration.</a> Proceedings of the National Academy of Sciences of the United States of America. 110 (33), 13416-13421 (2013).</li><li>Tryon, R. C., Johnson, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clonal+analysis+of+kit+ligand+a+functional+expression+reveals+lineage-specific+competence+to+promote+melanocyte+rescue+in+the+mutant+regenerating+caudal+fin.">Clonal analysis of kit ligand a functional expression reveals lineage-specific competence to promote melanocyte rescue in the mutant regenerating caudal fin.</a> PloS one. 9 (7), e102317 (2014).</li><li>Wehner, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wnt/beta-catenin+signaling+defines+organizing+centers+that+orchestrate+growth+and+differentiation+of+the+regenerating+zebrafish+caudal+fin.">Wnt/beta-catenin signaling defines organizing centers that orchestrate growth and differentiation of the regenerating zebrafish caudal fin.</a> Cell Rep. 6 (3), 467-481 (2014).</li><li>Huang, C. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conditional+expression+of+a+myocardium-specific+transgene+in+zebrafish+transgenic+lines.">Conditional expression of a myocardium-specific transgene in zebrafish transgenic lines.</a> Dev Dyn. 233 (4), 1294-1303 (2005).</li><li>Knopf, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dually+inducible+TetON+systems+for+tissue-specific+conditional+gene+expression+in+zebrafish.">Dually inducible TetON systems for tissue-specific conditional gene expression in zebrafish.</a> Proceedings of the National Academy of Sciences of the United States of America. 107 (46), 19933-19938 (2010).</li><li>Provost, E., Rhee, J., Leach, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viral+2A+peptides+allow+expression+of+multiple+proteins+from+a+single+ORF+in+transgenic+zebrafish+embryos.">Viral 2A peptides allow expression of multiple proteins from a single ORF in transgenic zebrafish embryos.</a> Genesis. 45 (10), 625-629 (2007).</li><li>Suster, M. L., Abe, G., Schouw, A., Kawakami, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transposon-mediated+BAC+transgenesis+in+zebrafish.">Transposon-mediated BAC transgenesis in zebrafish.</a> Nat Protoc. 6 (12), 1998-2021 (2011).</li><li>Bussmann, J., Schulte-Merker, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+BAC+selection+for+tol2-mediated+transgenesis+in+zebrafish.">Rapid BAC selection for tol2-mediated transgenesis in zebrafish.</a> Development. 138 (19), 4327-4332 (2011).</li><li>Yuan, S., Sun, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microinjection+of+mRNA+and+morpholino+antisense+oligonucleotides+in+zebrafish+embryos.">Microinjection of mRNA and morpholino antisense oligonucleotides in zebrafish embryos.</a> J Vis Exp. (27), (2009).</li><li>Kim, J. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+cleavage+efficiency+of+a+2A+peptide+derived+from+porcine+teschovirus-1+in+human+cell+lines,+zebrafish+and+mice.">High cleavage efficiency of a 2A peptide derived from porcine teschovirus-1 in human cell lines, zebrafish and mice.</a> PloS one. 6 (4), e18556 (2011).</li><li>Matthews, M., Varga, Z. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anesthesia+and+euthanasia+in+zebrafish.">Anesthesia and euthanasia in zebrafish.</a> ILAR journal / National Research Council, Institute of Laboratory Animal Resources. 53 (2), 192-204 (2012).</li><li>Hyde, D. R., Godwin, A. R., Thummel, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+electroporation+of+morpholinos+into+the+regenerating+adult+zebrafish+tail+fin.">In vivo electroporation of morpholinos into the regenerating adult zebrafish tail fin.</a> J Vis Exp. (61), (2012).</li><li>Meeker, N. D., Hutchinson, S. A., Ho, L., Trede, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+for+isolation+of+PCR-ready+genomic+DNA+from+zebrafish+tissues.">Method for isolation of PCR-ready genomic DNA from zebrafish tissues.</a> Biotechniques. 43 (5), 610 (2007).</li><li>Thermes, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=I-SceI+meganuclease+mediates+highly+efficient+transgenesis+in+fish.">I-SceI meganuclease mediates highly efficient transgenesis in fish.</a> Mech Dev. 118 (1-2), 91-98 (2002).</li><li>Suster, M. L., Kikuta, H., Urasaki, A., Asakawa, K., Kawakami, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transgenesis+in+zebrafish+with+the+tol2+transposon+system.">Transgenesis in zebrafish with the tol2 transposon system.</a> Methods Mol Biol. , 56141-56163 (2009).</li><li>Grabher, C., Wittbrodt, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Meganuclease+and+transposon+mediated+transgenesis+in+medaka.">Meganuclease and transposon mediated transgenesis in medaka.</a> Genome Biol. 8, (2007).</li></ol>

Los autores no tienen nada que revelar.

El pez cebra adulto tiene una asombrosa capacidad para regenerar con éxito a muchos órganos y apéndices internos. Un conocimiento profundo de los mecanismos moleculares y celulares implicados requiere un análisis específico de tejido de las funciones de genes y vías de señalización. Hacia esto, el sistema de Teton ofrece una herramienta eficaz para la expresión génica espaciotemporalmente controlada en el pez cebra embrionarias y adultas. Las construcciones del sistema de Teton y la metodología descritos en e...

El pez cebra es un organismo vertebrado modelo bien establecido para estudiar muchos aspectos del desarrollo, fisiología, la enfermedad, y la regeneración. Con la creciente adopción de pez cebra como modelo para los procesos biológicos post-embrionarias, herramientas experimentales para la manipulación inducible, específico de tejido de la expresión génica o vías de señalización se han convertido cada vez más importante. En particular, los estudios sobre la regeneración de órganos y apéndice en el pez cebra adultos han sufrido de una falta de herramientas para la disección de los requisitos de espacio-temporales de las vías de señalización durante estos procesos regenerativos. Actualmente, tres sistemas diferentes se han utilizado para lograr condicional, expresión específica de tejido del gen en la regeneración de órganos del pez cebra adultos: el sistema Cre-lox, la expresión mosaico de choque térmico transgenes inducibles utilizando transgénesis somática mediada por transposón, y el sistema de téton 1 -3. Téton refiere a una variante de una tetraciclina-contsistema de activación transcripcional laminado, donde se activa la expresión en presencia del antibiótico tetraciclina o un derivado, por ejemplo, doxiciclina. El sistema Cre-lox, ya que hasta ahora se ha utilizado en peces adultos, se basa en una recombinasa Cre controlada por tamoxifeno (CreERT2), cuya expresión está restringida espacialmente por elementos reguladores específicos de tejido. Eliminación impulsado por Cre de un casete de STOP facilita la expresión del gen de interés dirigido por un promotor que debe ser activo en todos los tipos celulares 1. Creación transposón mediada de transgenes somáticas mosaically expresadas proporciona un sistema para la expresión del transgén inducible en linajes de células individuales. La inyección de embriones de pez cebra con un transposón Tol2 que lleva un gen de interés bajo el control transcripcional de un promotor de choque térmico resultados en individuos quiméricos típicamente llevan el transgén sólo en linajes de células discretas de un órgano de regeneración 2. Mientras que ambos sistemas permiten condicional tejido-spela expresión génica especí-, el sistema Cre-lox no es reversible, y la estrategia de etiquetado usando clonal basado en transposón sufre de su naturaleza estocástica. Por lo tanto, nosotros y otros han adaptado recientemente sistemas Teton transgénicas para su uso en el pez cebra, que facilitan temporal y la expresión génica controlada espacialmente que está en sintonizable Además y reversible 3-5. El sistema de Teton utilizado aquí comprende una línea piloto transgénico (TetActivator) en el que un doxiciclina (DOX) activador transcripcional inducible (mejoró transactivador de tetraciclina inversa, irtTA, corta TETA) está bajo el control de secuencias reguladoras genómicas específicas de tejido. En segundo lugar, se requiere una línea transgénica respondedor (TetResponder) que alberga un gen de interés bajo el control transcripcional del operador de tetraciclina (Tet elemento de respuesta; Tetre) (Figura 1A). Por lo tanto, el uso de combinaciones específicas de TetActivator y TetResponder líneas permite condicional tejido-específicaFIC manipulación de la expresión génica. Hemos utilizado recientemente el sistema téton para sondar para las funciones específicas de tejido de señalización Wnt / beta-catenina en el adulto regeneración de cola de pez cebra de la aleta 3. En el protocolo descrito aquí se describe un flujo de trabajo para la puesta a punto y la utilización del sistema de Teton en el pez cebra, en particular, para el estudio de la regeneración de la aleta. Esto incluye instrucciones detalladas sobre cómo generar líneas TetActivator y TetResponder transgénicas estables y un protocolo para la inducción del transgen en embriones de pez cebra y adulto. Además, se describen técnicas para la verificación de la expresión génica específica de tejido en los regenerados aleta, incluyendo un protocolo para la preparación de criosecciones de aletas de pez cebra adultos. Adicionalmente, se discuten consideraciones para el diseño del transgén TetActivator, la elección de un método de transgénesis, y detección de la expresión TetResponder. Por lo tanto, el objetivo general de este protocolo es la de servir como modelopara el establecimiento de un sistema de seguimiento téton funcional en el pez cebra para lograr la expresión de genes condicional específica de tejido, que se puede aplicar a cualquier tejido de interés. Hemos creado un vector TetActivator permitiendo I-SCE o la generación mediada Tol2 de líneas TetActivator estables utilizando secuencias reguladoras genómicas cortas (fragmentos potenciador; Weidinger base de datos plásmido laboratorio no 1247;. Figura 1B). Este constructo contiene un casete TetActivator que consiste en la variante mutante M2 del dominio inverso represor Tet fusionado con el virus Herpes simplex VP16 transactivación-dominio derivado 3F [irtTAM2 (3F)]. Expresión de la TetActivator (TETA) se puede monitorizar fácilmente ya que es co-expresada con la AmCyan fluoróforo desde el mismo marco de lectura abierto; un péptido p2a media saltar ribosomal, que debería dar lugar a la producción de la Teta y AmCyan como proteínas separadas en una relación 1: 5,6 1. El constructo también contiene un poylinker 5 &#39;de la TetActivator casete para facilitar la inserción de secuencias reguladoras genómicas de interés usando métodos de clonación convencionales. Además, hemos creado un constructo que consiste en el casete descrito anteriormente TetActivator además de un casete de selección de kanamicina (Weidinger base de datos plásmido laboratorio no 1180;. Figura 1C), que puede ser recombinado en un cromosoma artificial bacteriano (BAC) que contiene una gran región genómica ( por lo general en el codón de inicio de un gen cuya expresión patrón es para ser imitado por el transgén). Ambas construcciones están disponibles en el laboratorio de Weidinger bajo petición.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Breeding boxes</td>
			<td>Aqua Schwarz</td>
			<td>AquaBox 1</td>
			<td></td>
		</tr>
		<tr>
			<td>Compound fluorescent microscope</td>
			<td>e.g. Leica, Zeiss</td>
			<td>varies with the manufacturer</td>
			<td>to image fluorescent tissue sections</td>
		</tr>
		<tr>
			<td>Confocal microscope</td>
			<td>e.g. Leica, Zeiss</td>
			<td>varies with the manufacturer</td>
			<td>to image fluorescent tissue sections</td>
		</tr>
		<tr>
			<td>Cryostat</td>
			<td>e.g. Leica, Thermo-Scientific</td>
			<td>varies with the manufacturer</td>
			<td>for cryosectioning</td>
		</tr>
		<tr>
			<td>4&#8217;, 6- diamidino-2-phenylinodole (Dapi)</td>
			<td>Sigma-Aldrich</td>
			<td>D9542</td>
			<td>use 1/5000 in PBS 
			for visualization of nuclei</td>
		</tr>
		<tr>
			<td>Doxycycline</td>
			<td>Sigma-Aldrich</td>
			<td>D9891</td>
			<td>prepare stocks in 50% EtOH at 50 mg/ml (97 mM) 
			for TetResponder induction</td>
		</tr>
		<tr>
			<td>E3 embryo medium&#160;</td>
			<td></td>
			<td></td>
			<td>5 mM NaCl, 0.17 mM KCl, 0.33 mM CaCl2&#903; 2 H2O, 0.33 mM MgSO4&#903;7 H2O, 0.2 &#8240; (w/v) methylene blue, pH 6.5 
			for embryo/larvae husbandry</td>
		</tr>
		<tr>
			<td>Paraformaldehyde (PFA)</td>
			<td>Sigma-Aldrich</td>
			<td>P6148</td>
			<td>4 % (w/v) paraformaldehyde in PBS, pH 7.5 
			for fixation</td>
		</tr>
		<tr>
			<td>1x Phosphat-buffer saline (PBS)</td>
			<td></td>
			<td></td>
			<td>1.7 mM KH2PO4, 5.2 mM Na2HPO4, 150 mM NaCl, pH 7.5</td>
		</tr>
		<tr>
			<td>1x Phosphat-buffer saline + Tween 20 (PBT)</td>
			<td></td>
			<td></td>
			<td>1x PBS with 0.1 % Tween 20</td>
		</tr>
		<tr>
			<td>Superfrost Ultra Plus adhesion microscope slides</td>
			<td>Thermo Scientific&#160;</td>
			<td>1014356190</td>
			<td>for collection of tissue sections</td>
		</tr>
		<tr>
			<td>Stereo fluorescent microscope</td>
			<td>e.g. Leica, Zeiss</td>
			<td>varies with the manufacturer</td>
			<td>for fluorescence-based genotyping</td>
		</tr>
		<tr>
			<td>Thermocycler</td>
			<td>e.g. Biorad, Applied Biosystems</td>
			<td>varies with the manufacturer</td>
			<td>for PCR-based genotyping</td>
		</tr>
		<tr>
			<td>Tissue freezing medium (TFM)</td>
			<td>Triangel Biomedical Sciences</td>
			<td>TFM-C</td>
			<td>for embedding of tissue samples</td>
		</tr>
		<tr>
			<td>Tricaine (L-Ethyl-m-amino-benzoate-methane sulfonate/MS-222)</td>
			<td>Sigma-Aldrich</td>
			<td>E10521</td>
			<td>for anesthesia 
			use at 1 mg/ml in E3 embryo medium</td>
		</tr>
	</tbody>
</table>

use of the teton system to study molecular mechanisms of zebrafish regeneration

The zebrafish has become a very important model organism for studying vertebrate development, physiology, disease, and tissue regeneration. A thorough understanding of the molecular and cellular mechanisms involved requires experimental tools that allow for inducible, tissue-specific manipulation of gene expression or signaling pathways. Therefore, we and others have recently adapted the TetON system for use in zebrafish. The TetON system facilitates temporally and spatially-controlled gene expression and we have recently used this tool to probe for tissue-specific functions of Wnt/beta&#8211;catenin signaling during zebrafish tail fin regeneration. Here we describe the workflow for using the TetON system to achieve inducible, tissue-specific gene expression in the adult regenerating zebrafish tail fin. This includes the generation of stable transgenic TetActivator and TetResponder lines, transgene induction and techniques for verification of tissue-specific gene expression in the fin regenerate. Thus, this protocol serves as blueprint for setting up a functional TetON system in zebrafish and its subsequent use, in particular for studying fin regeneration.

Establecer un sistema de Teton funcional para la expresión génica inducible específico de tejido, TetActivator transgénicos y líneas TetResponder necesitar ser generado (Figura 1A). Esto se logra mediante la microinyección de TetActivator (Figura 1B - C) o TetResponder (Figura 1E) constructos en embriones de pez cebra temprana y posterior integración de la línea germinal. Construcciones TetActivator funcionales pueden ser generados ya sea por cl...

Watch this Scientific Journal Video about Use of the TetON System to Study Molecular Mechanisms of Zebrafish Regeneration at JoVE.com

Use of the TetON System to Study Molecular Mechanisms of Zebrafish Regeneration

Here we outline the workflow for using the TetON system to achieve tissue-specific gene expression in the adult regenerating zebrafish tail fin.

El uso del Sistema de Teton para estudiar los mecanismos moleculares de la regeneración de pez cebra

The zebrafish has become a very important model organism for studying vertebrate development, physiology, disease, and tissue regeneration. A thorough ...

use-teton-system-to-study-molecular-mechanisms-zebrafish

Research

JoVE Journal

Developmental Biology

10.6K vistas.  Ulm University. Here we outline the workflow for using the TetON system to achieve tissue-specific gene expression in the adult regenerating zebrafish tail fin.

Video: Use of the TetON System to Study Molecular Mechanisms of Zebrafish Regeneration

Hepatocyte-specific Ablation in Zebrafish to Study Biliary-driven Liver Regeneration

The liver has a great capacity to regenerate. Hepatocytes, the parenchymal cells of the liver, can regenerate in one of two ways: hepatocyte- or biliary-driven liver regeneration. In hepatocyte-driven liver regeneration, regenerating hepatocytes are derived from preexisting hepatocytes, whereas, in biliary-driven regeneration, regenerating hepatocytes are derived from biliary epithelial cells (BECs). For hepatocyte-driven liver regeneration, there are excellent rodent models that have significantly contributed to the current understanding of liver regeneration. However, no such rodent model exists for biliary-driven liver regeneration. We recently reported on a zebrafish liver injury model in which BECs extensively give rise to hepatocytes upon severe hepatocyte loss. In this model, hepatocytes are specifically ablated by a pharmacogenetic means. Here we present in detail the methods to ablate hepatocytes and to analyze the BEC-driven liver regeneration process. This hepatocyte-specific ablation model can be further used to discover the underlying molecular and cellular mechanisms of biliary-driven liver regeneration. Moreover, these methods can be applied to chemical screens to identify small molecules that augment or suppress liver regeneration.

To help assess the molecular mechanisms underlying zebrafish biliary-driven liver regeneration, we established a liver injury model in which the nitroreductase-expressing hepatocytes are genetically ablated upon metronidazole treatment. In this protocol, we describe how to adeptly manipulate, monitor and analyze hepatocyte ablation and biliary-driven liver regeneration.

Ablación específico de hepatocitos en pez cebra para estudiar biliar impulsada regeneración hepática

The liver has a great capacity to regenerate. Hepatocytes, the parenchymal cells of the liver, can regenerate in one of two ways: hepatocyte- or ...

Investigación

Biología del Desarrollo

Tracking Cells in GFP-transgenic Zebrafish Using the Photoconvertible PSmOrange System

The rapid development of transparent zebrafish embryos (Danio rerio) in combination with fluorescent labelings of cells and tissues allows visualizing developmental processes as they happen in the living animal. Cells of interest can be labeled by using a tissue specific promoter to drive the expression of a fluorescent protein (FP) for the generation of transgenic lines. Using fluorescent photoconvertible proteins for this purpose additionally allows to precisely follow defined structures within the expression domain. Illuminating the protein in the region of interest, changes its emission spectrum and highlights a particular cell or cell cluster leaving other transgenic cells in their original color. A major limitation is the lack of known promoters for a large number of tissues in the zebrafish. Conversely, gene- and enhancer trap screens have generated enormous transgenic resources discretely labeling literally all embryonic structures mostly with GFP or to a lesser extend red or yellow FPs. An approach to follow defined structures in such transgenic backgrounds would be to additionally introduce a ubiquitous photoconvertible protein, which could be converted in the cell(s) of interest. However, the photoconvertible proteins available involve a green and/or less frequently a red emission state1 and can therefore often not be used to track cells in the FP-background of existing transgenic lines. To circumvent this problem, we have established the PSmOrange system for the zebrafish2,3. Simple microinjection of synthetic mRNA encoding a nuclear form of this protein labels all cell nuclei with orange/red fluorescence. Upon targeted photoconversion of the protein, it switches its emission spectrum to far red. The quantum efficiency and stability of the protein makes PSmOrange a superb cell-tracking tool for zebrafish and possibly other teleost species.

We established the photoconvertible PSmOrange system as a powerful, straight-forward and cost inexpensive tool for in vivo cell tracking in GFP transgenic backgrounds. This protocol describes its application in the zebrafish model system.

El seguimiento de las células en el pez cebra transgénico GFP-Uso del sistema de fotoconvertible PSmOrange

The rapid development of transparent zebrafish embryos (Danio rerio) in combination with fluorescent labelings of cells and tissues allows visualizing ...

Development of an Ethanol-induced Fibrotic Liver Model in Zebrafish to Study Progenitor Cell-mediated Hepatocyte Regeneration

Sustained liver fibrosis with continuation of extracellular matrix (ECM) protein build-up results in the loss of cellular competency of the liver, leading to cirrhosis with hepatocellular dysfunction. Among multiple hepatic insults, alcohol abuse can lead to significant health problems including liver failure and hepatocellular carcinoma. Nonetheless, the identity of endogenous cellular sources that regenerate hepatocytes in response to alcohol has not been properly investigated. Moreover, few studies have effectively modeled hepatocyte regeneration upon alcohol-induced injury. We recently reported on establishing an ethanol (EtOH)-induced fibrotic liver model in zebrafish in which hepatic progenitor cells (HPCs) gave rise to hepatocytes upon near-complete hepatocyte loss in the presence of fibrogenic stimulus. Furthermore, through chemical screens using this model, we identified multiple small molecules that enhance hepatocyte regeneration. Here we describe in detail the procedures to develop an EtOH-induced fibrotic liver model and to perform chemical screens using this model in zebrafish. This protocol will be a critical tool to delineate the molecular and cellular mechanisms of how hepatocyte regenerates in the fibrotic liver. Furthermore, these methods will facilitate potential discovery of novel therapeutic strategies for chronic liver disease in vivo.

Sustained fibrosis with deposition of excessive extracellular matrix proteins leads to cirrhosis. Alcohol abuse is one of the main causes of severe liver disease. We established an ethanol-induced zebrafish fibrotic liver model to study the mechanisms and strategies of promoting hepatocyte regeneration upon alcohol-induced injury.

Desarrollo de un Modelo de hígado fibrótico inducida por etanol en el pez cebra para el Estudio de células progenitoras mediada por la regeneración de hepatocitos

Sustained liver fibrosis with continuation of extracellular matrix (ECM) protein build-up results in the loss of cellular competency of the liver, leading ...

Use of Immunolabeling to Analyze Stable, Dynamic, and Nascent Microtubules in the Zebrafish Embryo

Microtubules (MTs) are dynamic and fragile structures that are challenging to image in vivo, particularly in vertebrate embryos. Immunolabeling methods are described here to analyze distinct populations of MTs in the developing neural tube of the zebrafish embryo. While the focus is on neural tissue, this methodology is broadly applicable to other tissues. The procedures are optimized for early to mid-somitogenesis-stage embryos (1 somite to 12 somites), however they can be adapted to a range of other stages with relatively minor adjustments. The first protocol provides a method to assess the spatial distribution of stable and dynamic MTs and perform a quantitative analysis of these populations with image-processing software. This approach complements existing tools to image microtubule dynamics and distribution in real-time, using transgenic lines or transient expression of tagged constructs. Indeed, such tools are very useful, however they do not readily distinguish between dynamic and stable MTs. The ability to image and analyze these distinct microtubule populations has important implications for understanding mechanisms underlying cell polarization and morphogenesis. The second protocol outlines a technique to analyze nascent MTs specifically. This is accomplished by capturing the de novo growth properties of MTs over time, following microtubule depolymerization with the drug nocodazole and a recovery period after drug washout. This technique has not yet been applied to the study of MTs in zebrafish embryos, but is a valuable assay for investigating the in vivo function of proteins implicated in microtubule assembly.

Immunolabeling methods to analyze distinct populations of microtubules in the developing zebrafish brain are described here, which are broadly applicable to other tissues. The first protocol outlines an optimized method for immunolabeling stable and dynamic microtubules. The second protocol provides a method to image and quantify nascent microtubules specifically.

Uso de inmunomarcación para analizar microtúbulos estables, dinámicos y emergente en el embrión de pez cebra

Microtubules (MTs) are dynamic and fragile structures that are challenging to image in vivo, particularly in vertebrate embryos. Immunolabeling methods ...

Methods for the Study of Regeneration in Stentor

Cells need to be able to regenerate their parts to recover from external perturbations. The unicellular ciliate Stentor coeruleus is an excellent model organism to study wound healing and subsequent cell regeneration. The Stentor genome became available recently, along with modern molecular biology methods, such as RNAi. These tools make it possible to study single-cell regeneration at the molecular level. The first section of the protocol covers establishing Stentor cell cultures from single cells or cell fragments, along with general guidelines for maintaining Stentor cultures. Culturing Stentor in large quantities allows for the use of valuable tools like biochemistry, sequencing, and mass spectrometry. Subsequent sections of the protocol cover different approaches to inducing regeneration in Stentor. Manually cutting cells with a glass needle allows studying the regeneration of large cell parts, while treating cells with either sucrose or urea allows studying the regeneration of specific structures located at the anterior end of the cell. A method for imaging individual regenerating cells is provided, along with a rubric for staging and analyzing the dynamics of regeneration. The entire process of regeneration is divided in three stages. By visualizing the dynamics of the progression of a population of cells through the stages, the heterogeneity in regeneration timing is demonstrated.

Methods for the Study of Regeneration in Stentor

The giant ciliate, Stentor coeruleus, is an excellent system to study regeneration and wound healing. We present procedures for establishing Stentor cell cultures from single cells or cell fragments, inducing regeneration by cutting cells, chemically inducing the regeneration of membranellar band and oral apparatus, imaging, and analysis of cell regeneration.

Métodos para el estudio de la regeneración en Stentor

Cells need to be able to regenerate their parts to recover from external perturbations. The unicellular ciliate Stentor coeruleus is an excellent model ...

Whole-Mount In Situ Hybridization in Zebrafish Embryos and Tube Formation Assay in iPSC-ECs to Study the Role of Endoglin in Vascular Development

Vascular development is determined by the sequential expression of specific genes, which can be studied by performing in situ hybridization assays in zebrafish during different developmental stages. To investigate the role of endoglin(eng) in vessel formation during the development of hereditary hemorrhagic telangiectasia&#160;(HHT), morpholino-mediated targeted knockdown of eng in zebrafish are used to study its temporal expression and associated functions. Here, whole-mount in situ RNA hybridization (WISH) is employed for the analysis of eng and its downstream genes in zebrafish embryos. Also, tube formation assays are performed in HHT patient-derived induced pluripotent stem cell-differentiated&#160;endothelial cells (iPSC-ECs; with eng mutations). A specific signal amplifying system using the whole amount In Situ Hybridization &#8211; WISH provides higher resolution and lower background results compared to traditional methods. To obtain a better signal, the post-fixation time is adjusted to 30 min after probe hybridization. Because fluorescence staining is not sensitive in zebrafish embryos, it is replaced with diaminobezidine (DAB) staining here. In this protocol, HHT&#160;patient-derived iPSC lines containing an eng mutation are differentiated into endothelial cells. After coating a plate with basement membrane matrix for 30 min at 37 &#176;C, iPSC-ECs are seeded as a monolayer into wells and kept at 37 &#176;C for 3 h. Then, the tube length and number of branches are calculated using microscopic images. Thus, with this improved WISH protocol, it is shown that reduced eng expression affects endothelial progenitor formation in zebrafish embryos. This is further confirmed by tube formation assays using iPSC-ECs derived from a patient with HHT. These assays confirm the role for eng in early vascular development.

Presented here is a protocol for whole-mount in situ RNA hybridization analysis in zebrafish and tube formation assay in patient-derived induced pluripotent stem cell-derived endothelial cells to study the role of endoglin in vascular formation.

Hibridación en situ de montaje completo en embriones de pez cebra y ensayo de formación de tubos en iPSC-CE para estudiar el papel de la endoglina en el desarrollo vascular

Vascular development is determined by the sequential expression of specific genes, which can be studied by performing in situ hybridization assays in ...

Examining Muscle Regeneration in Zebrafish Models of Muscle Disease

Skeletal muscle has a remarkable ability to regenerate following injury, which is driven by obligate tissue resident muscle stem cells. Following injury, the muscle stem cell is activated and undergoes cell proliferation to generate a pool of myoblasts, which subsequently differentiate to form new muscle fibers. In many muscle wasting conditions, including muscular dystrophy and ageing, this process is impaired resulting in the inability of muscle to regenerate. The process of muscle regeneration in zebrafish is highly conserved with mammalian systems providing an excellent system to study muscle stem cell function and regeneration, in muscle wasting conditions such as muscular dystrophy. Here, we present a method to examine muscle regeneration in zebrafish models of muscle disease. The first step involves the use of a genotyping platform that allows the determination of the genotype of the larvae prior to eliciting an injury. Having determined the genotype, the muscle is injured using a needle stab, following which polarizing light microscopy is used to determine the extent of muscle regeneration. We therefore provide a high throughput pipeline which allows the examination of muscle regeneration in zebrafish models of muscle disease.

Skeletal muscle regeneration is driven by tissue resident muscle stem cells, which are impaired in many muscle diseases such as muscular dystrophy, and this results in the inability of muscle to regenerate. Here, we describe a protocol that allows the examination of muscle regeneration in zebrafish models of muscle disease.

Examinando la regeneración muscular en modelos de pez cebra de enfermedad muscular

Skeletal muscle has a remarkable ability to regenerate following injury, which is driven by obligate tissue resident muscle stem cells. Following injury, ...

Light-Induced GFP Expression in Zebrafish Embryos using the Optogenetic TAEL/C120 System

Inducible gene expression systems are an invaluable tool for studying biological processes. Optogenetic expression systems can provide precise control over gene expression timing, location, and amplitude using light as the inducing agent. In this protocol, an optogenetic expression system is used to achieve light-inducible gene expression in zebrafish embryos. This system relies on an engineered transcription factor called TAEL based on a naturally occurring light-activated transcription factor from the bacterium E. litoralis. When illuminated with blue light, TAEL dimerizes, binds to its cognate regulatory element called C120, and activates transcription. This protocol uses transgenic zebrafish embryos that express the TAEL transcription factor under the control of the ubiquitous ubb promoter. At the same time, the C120 regulatory element drives the expression of a fluorescent reporter gene (GFP). Using a simple LED panel to deliver activating blue light, induction of GFP expression can first be detected after 30 min of illumination and reaches a peak of more than 130-fold induction after 3 h of light treatment. Expression induction can be assessed by quantitative real-time PCR (qRT-PCR) and by fluorescence microscopy. This method is a versatile and easy-to-use approach for optogenetic gene expression.

Optogenetics is a powerful tool with wide-ranging applications. This protocol demonstrates how to achieve light-inducible gene expression in zebrafish embryos using the blue light-responsive TAEL/C120 system.

Expresión de GFP inducida por la luz en embriones de pez cebra utilizando el sistema optogenético TAEL/C120

Inducible gene expression systems are an invaluable tool for studying biological processes. Optogenetic expression systems can provide precise control ...

Eye Removal in Living Zebrafish Larvae to Examine Innervation-dependent Growth and Development of the Visual System

Zebrafish exhibit remarkable life-long growth and regenerative abilities. For example, specialized stem cell niches established during embryogenesis support continuous growth of the entire visual system, both in the eye and the brain. Coordinated growth between the retinae and the optic tectum ensures accurate retinotopic mapping as new neurons are added in the eyes and brain. To address whether retinal axons provide crucial information for regulating tectal stem and progenitor cell behaviors such as survival, proliferation, and/or differentiation, it is necessary to be able to compare innervated and denervated tectal lobes within the same animal and across animals. 
Surgical removal of one eye from living larval zebrafish followed by observation of the optic tectum achieves this goal. The accompanying video demonstrates how to anesthetize larvae, electrolytically sharpen tungsten needles, and use them to remove one eye. It next shows how to dissect brains from fixed zebrafish larvae. Finally, the video provides an overview of the protocol for immunohistochemistry and a demonstration of how to mount stained embryos in low-melting-point agarose for microscopy.

The article explains how to surgically remove eyes from living zebrafish larvae as the first step toward investigating how retinal input influences optic tectum growth and development. In addition, the article provides information about larval anesthetization, fixation, and brain dissection, followed by immunohistochemistry and confocal imaging.

Extirpación de ojos en larvas vivas de pez cebra para examinar el crecimiento dependiente de la inervación y el desarrollo del sistema visual

Zebrafish exhibit remarkable life-long growth and regenerative abilities. For example, specialized stem cell niches established during embryogenesis ...

Primary Cell Cultures to Study the Regeneration Potential of Murine M&#252;ller Glia after MicroRNA Treatment

M&#252;ller glia (MG) are the predominant glia in the neural retina and can function as a regenerative source for retinal neurons. In lower vertebrates such as fish, MG-driven regeneration occurs naturally; in mammals, however, stimulation with certain factors or genetic/epigenetic manipulation is required. Since MG comprise only 5% of the retinal cell population, there is a need for model systems that allow the study of this cell population exclusively. One of these model systems is primary MG cultures that are reproducible and can be used for a variety of applications, including molecule/factor screening and identification, testing of compounds or factors, cell monitoring, and/or functional tests. This model is used to study the potential of murine MG to convert into retinal neurons after supplementation or inhibition of microRNAs (miRNAs) via transfection of artificial miRNAs or their inhibitors. The use of MG-specific reporter mice in combination with immunofluorescent labeling and single-cell RNA sequencing (scRNA-seq) confirmed that 80%-90% of the cells found in these cultures are MG. Using this model, it was discovered that miRNAs can reprogram MG into retinal progenitor cells (RPCs), which subsequently differentiate into neuronal-like cells. The advantages of this technique are that miRNA candidates can be tested for their efficiency and outcome before their usage in in vivo applications.

Primary Cell Cultures to Study the Regeneration Potential of Murine M&amp;#252;ller Glia after MicroRNA Treatment

M&#252;ller glia primary cultures obtained from mouse retinas represent a very robust and reliable tool to study the glial conversion into retinal progenitor cells after microRNA treatment. Single molecules or combinations can be tested before their subsequent application of in vivo approaches.

Cultivos celulares primarios para estudiar el potencial de regeneración de la glía murina de Müller después del tratamiento con microARN

M&#252;ller glia (MG) are the predominant glia in the neural retina and can function as a regenerative source for retinal neurons. In lower vertebrates ...