We thank Lowell Cochran for expert videography assistance. The financial assistance of the Canadian Institutes of Health Research (CIHR), the Canadian Breast Cancer Foundation (CBCF, Ontario Chapter), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Breast Cancer Research Alliance, the Ontario Centers of Excellence, the Breast Cancer Action Kingston and the Clare Nelson bequest fund through grants to LR is gratefully acknowledged. SG was the recipient of an NSERC studentship. MG was supported by a postdoctoral fellowship from the US Army Breast Cancer Program, the Ministry of Research and Innovation of the Province of Ontario and the Advisory Research Committee of Queen&#8217;s University.

1. Ausplattieren der Zellen in der Elektroporation Chambers <ol><li> In einer Laminar-Flow-Haube, trypsinieren die Zellen unter Verwendung von sterilen Technik wie gewohnt. HINWEIS: Es ist sehr wichtig, um durch Zentrifugation beseitigt alle Spuren von Trypsin, weil sie verhindern Ausbreitung der Zellen auf dem Glas, damit die Bildung von adherens und Gap Junctions. </li><li> Pipette 1 ml der Zellsuspension in sterilen Kammern Elektroporation mit dem in-situ-Elektroporator (Figur 1), und in ein 37 ° C, CO 2-Inkubator gestellt. HINWEIS: Die Zelladhäsion durch Plattieren auf Fibronektin, Kollagen, Poly-Lysin oder Zell-und Gewebekleber (siehe Materialien Table) verbessert werden. </li><li> Wenn die Zellen eine konfluente Schicht gebildet sie sind bereit für GJIC Prüfung. </li></ol> 2. Verfahren der Elektroporation Elektroporation für GJIC Prüfung kann außerhalb einer Laminar-Flow-Haube durchgeführt werden,da es dauert nur ein paar Minuten. Wenn längere Inkubationszeiten für ein bestimmtes Experiment erforderlich ist, dann kann es vollständig in einem Abzug mit laminarer Strömung durchgeführt werden. In allen Fällen müssen die Kammern, in denen die Zellen gezüchtet steril sein. <ol><li> Bereiten Sie eine 5 mg / ml Lucifer gelb Lösung: 10 mg LY-Pulver (mit dem Elektroporator vorgesehen) in 2 ml calciumfreien Wachstumsmedium. Für Experimente, die längere Inkubationszeiten erfordert, Filter-Lösung sterilisieren und bei 4 o C </li><li> Saugen Sie das Wachstumsmedium und waschen Sie die Zellen mit Calcium-freiem Medium, man aufpassen, nicht auf die Monoschicht zerkratzen oder trocknen die Zellen. Wenn die Zellen getrocknet haben sie meist dunkler Kerne und abholen LY ohne Elektroporation. Die Wirkung ist stärker ausgeprägt in der Mitte des Schiebers das mehr Luftzug (4F) ausgesetzt ist. </li><li> Mit einer Eppendorf-Pipette pipettiert die Farbstofflösung auf die Zellen (400 ul für die ganze Kammer), am Rand der Kammer, being darauf, nicht die Zellschicht zu berühren. </li><li> Legen Sie die Kammer, in der mit dem mitgelieferten Halter Elektroporator und wenden Sie einen Impuls von der entsprechenden Stärke (siehe Diskussion). </li><li> Sorgfältig absaugen einige der LY-Lösung. Es kann ein zweites Mal für weniger wichtige Experimente verwendet werden. </li><li> Zusatz von Calcium-freiem DMEM mit 10% dialysierten Serum. </li><li> Die Zellen für 3-5 min im Brutschrank inkubieren, um die Farbstoffübertragung durch Gap Junctions ermöglichen. HINWEIS: Die Einbeziehung der dialysierten Serum an dieser Stelle hilft Porenverschluss. </li><li> Mit Calcium-freiem DMEM für Live Cell Beobachtung waschen Sie die nicht rechtsfähige Farbstoff. Alternativ können die Zellen in diesem Stadium durch Zugabe von 4% Formaldehyd zu der gut fixiert werden kann, und dann mit PBS (Phosphat-gepufferte Salzlösung) gewaschen. In allen Fällen muss die Wasch alle Hintergrund zu entfernen. HINWEIS: In Vorversuchen die optimalen Bedingungen zu bestimmen, wenn die Spannung zu niedrig ist, dann ist es möglich, die Zellen zu gewinnen in der incubato zu lassenr für ein paar Minuten und elektroporieren derselben Folie ein zweites Mal, um in den Kosten der Folien zu speichern. </li></ol> 3. Die mikroskopische Untersuchung <ol><li> Beachten Sie die Zellen unter Fluoreszenzbeleuchtung mit einem inversen Mikroskop mit dem geeigneten Filter für die verwendeten Farbstoffs ausgestattet. Lucifer gelb, Anregung 423nm, 555nm Emissions, WBV Filter für eine Nikon IX70 Mikroskop. </li><li> Beseitigen Meniskus Effekte, indem Sie ein Glas Deckglas auf der Oberseite des Kunststoff Nun, nach an die Spitze mit Flüssigkeit zu füllen, um die Zellmorphologie unter dem Phasenkontrast zu untersuchen. Für bessere Bilder kann das auch von der Folie abgenommen werden, und das Deckglas auf dem Rahmen angeordnet. Für feste Zellen, die gut mit Glycerin zur mikroskopischen Beobachtung gefüllt werden, während für lebende Zellen ist es mit Wachstumsmedium gefüllt werden. HINWEIS: Waschen und Fotografieren ist einfacher, wenn die Zellen mit Formaldehyd nach der Übertragung des Farbstoffes (Schritt 2.7 oben) festgelegt. Wenn die Zellen nichtt festgelegt ist, die Fluoreszenz von den Zellen innerhalb von etwa 60 min, je nach Zelltyp, die Spannung und den LY eingeführt, während in fixierten Zellen Fluoreszenz wird für mehrere Stunden beibehalten eliminiert. Allerdings verblasst oder Fluoreszenz verliert sich nach O / N Inkubation, auch in fixierten Zellen. Aus diesem Grund muss Fotografien bald nach der Elektroporation (Figur 2) entnommen werden. </li></ol> 4. Quantifizierung der interzellulären Kommunikation <ol><li> Fotografieren Sie die Zellen mit einem 20x-Objektiv unter Fluoreszenz-und Phasenkontrast (Abbildung 3). </li><li> Identifizieren und markieren mit einem Sternchen die elektroporiert Zellen an der Grenze zu den nicht-elektroporiert Bereich (Abbildung 2, Pfeil, Elektroporation Flanke). </li><li> Identifizieren und Markieren mit einem Punkt auf der fluoreszierenden Zellen nicht elektroporiert Seite, wo der Farbstoff durch Gap Junctions übertragen (3A und 3B). </li><li> Teilen Sie die Gesamtzahl derfluoreszierenden Zellen auf der nicht elektroporiert Bereich durch die Anzahl der elektroporierten Zellen entlang der Kante (3A und 3B). HINWEIS: Der Transfer von mindestens 200 zusammenhängenden elektroporiert Grenzzellen für jedes Experiment berechnet. Die erhaltene Zahl ist der Wert GJIC. </li></ol>

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The corresponding author is the inventor in a patent held by Queen&#8217;s University, which has been licensed to Cell Projects Inc. The company or the University had no influence upon the contents of the paper.

Kritische Schritte in dem Protokoll Elektroporiert Material Die Reinheit des Materials, elektroporiert werden, ist sehr wichtig. Wenn die Zellen sehr flach sind, müssen dann höhere Konzentrationen des Tracking-Farbstoff verwendet werden (bis zu 20 mg / ml für LY) und in solchen Fällen ist die Reinheit noch wichtiger als in Zellen, die mit einer kugelförmigen Form 1. Neben LY eine große Vielzahl von anderen Farbstoffen oder nonpermeant Moleküle eingeset...

Das Anlegen von elektrischem Strom an eine Zelle die Bildung von Poren in der Zellmembran durch ein Verfahren, genannt Elektroporation. Die Poren ermöglichen den Durchgang von einer Vielzahl von nonpermeant Moleküle durch die Membran. Das elektrische Feld kann präzise gesteuert werden, so daß die gebildeten Poren sind sehr klein und schnell wieder zu schließen, mit minimaler Störung der Zellphysiologie. Interessanterweise können anhaftende Zellen auf einem Objektträger mit einer leitfähigen und transparenten Indium-Zinn-Oxid (ITO) beschichtet und in situ elektroporiert, die auf der Oberfläche, wo sie wachsen angebaut werden, ohne abgelöst zu Suspension elektroporiert werden. Zellen können sehr gut auf dieser Fläche wachsen und wie sie gebunden sind, und erweiterte detaillierte mikroskopische Beobachtung möglich ist. Mit dieser Technik können kleine Moleküle nonpermeant sofort und eingeführt werden, in im wesentlichen 100% der Zellen, die diese Technik besonders für Studien über die Aktivierung comp machtonents eines Weges folgenden Liganden Stimulation eines Rezeptors (Übersicht in 1). Elektroporation wurde hauptsächlich für die Einführung von DNA (auch Elektrotransfektion) verwendet. Jedoch kann die Elektroporation in situ wertvoll für die Einführung einer großen Vielfalt von Molekülen, wie Peptiden 2-4, Oligonukleotide, wie Antisense-RNA, Doppelstrang-DNA-Decoy-Oligonukleotide zur Hemmung der Bindung von Transkriptionsfaktoren oder siRNA 3,5, 6, radioaktive Nukleotide 7-10, Proteine ​​11 12 oder 13 Pro-Drugs. Nach der Elektroporation können Zellen für biochemische Analysen lysiert oder fixiert und mit Antikörpern gefärbt. Die leitfähige ITO-Beschichtung ist sehr dünn, 800-1,000Å, so dass das Zellwachstum wird durch die Höhendifferenz der beiden Oberflächen gestört, da die Zellen wachsen über die Kante der leitenden Beschichtung. Dies bietet den Vorteil, dass nicht-electroporated Zellen elektroporiert mit denen gezüchtet werden Seite an Seite, um als Kontrollen dienen. Der gleiche Ansatz kann für die Prüfung von Gap Junction, interzelluläre Kommunikation (GJIC) verwendet werden, wie im Video beschrieben. Gap junctions sind Kanäle, welche die Innenräume von benachbarten Zellen 14. Gap Junction, spielt der interzellulären Kommunikation eine wichtige Rolle bei der Tumorentstehung und Metastasierung, während Onkogene wie Src unterdrücken GJIC 15,16. Zu prüfen GJIC einen fluoreszierenden Farbstoff, wie Lucifer Gelb (Ly) wird oft in kultivierte Zellen durch Mikroinjektion eingeführt oder kratzen Lade 17 und der Diffusion des Farbstoffs in die benachbarte Zellen mikroskopisch unter Fluoreszenzbeleuchtung beobachtet. Diese Techniken führen jedoch unweigerlich Zellschäden. Wir beschreiben nun ein Verfahren, bei dem Zellen auf einem Objektträger, der teilweise mit ITO beschichtet 18 gewachsen. Ein elektrischer Impuls wurde in Gegenwart von LY (oder anderen Farbstoffen) eingesetzt camit ihr Eindringen in die Zellen wachsen auf dem leitfähigen Teil des Schlittens, während die Farbstoffwanderung zu den benachbarten, nicht-elektroporierten Zellen wurde mikroskopisch durch Fluoreszenz-Beleuchtung beobachtet. Um störende empfindlichen Zellen, die dazu neigen, von der Monoschicht trennen zu vermeiden, um eine Anordnung entworfen, die nicht eine Elektrode erforderlich war oben auf die Zellen, um den elektrischen Strom 19 gelten platziert werden. Dieser Ansatz bietet die Möglichkeit, GJIC in einer großen Anzahl von Zellen zu quantifizieren, ohne nachweisbare Störungen der Zellstoffwechsel, da durch das Fehlen einer Wirkung auf die Länge der G1-Phase nach der Serumstimulation 12 angedeutet, Erhöhung des Niveaus der fos Protoonkogen Protein (Raptis, unveröffentlicht) oder zwei Kinasen mit zellulären Stress, der p38-Schwein oder JNK / SAPK-Kinase-1 verbunden. Dieser Ansatz ermöglicht die Untersuchung des Zusammenhangs zwischen den Ebenen der Onkogenexpression, Transformation und GJIC 18, sowie die Wirkung von Src und STAT3 auf GJIC in einer Vielzahl von Zelltypen, einschließlich Zellen aus Lungentumorproben 20-23 frisch kultiviert. Zusätzlich wird in situ Elektroporation mit dem beschriebenen Aufbau, der eine obere Elektrode wurde erfolgreich für den Nachweis der Gap-junction-Verschluss auf Adipozyten Differentiation eingesetzt fehlt, wobei die Zellanhaftung an das Substrat ist in diesem Stadium 19,24 verringert.

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			<td height="42" style="height:42px;width:179px;">Name of Material/ Equipment</td>
			<td style="width:428px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
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			<td height="21" style="height:21px;width:179px;">DMEM</td>
			<td style="width:428px;">Cellgro http://www.cellgro.com/</td>
			<td style="width:119px;">50-013-PB</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:179px;">DMEM without Calcium</td>
			<td style="width:428px;">Hyclone (Thermo scientific: http://www.thermoscientific.com)</td>
			<td style="width:119px;">SH30319-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Donor Calf Serum&#160;</td>
			<td style="width:428px;">PAA: http://www.paa.com/</td>
			<td style="width:119px;">Cat.# B15-008</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Fetal Bovine Serum</td>
			<td style="width:428px;">PAA: http://www.paa.com/</td>
			<td style="width:119px;">Cat.# A15-751</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Electroporation apparatus</td>
			<td style="width:428px;">Cell Projects Ltd UK: http://www.cellprojects.com/</td>
			<td style="width:119px;">ACE-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Chambers</td>
			<td style="width:428px;">Cell Projects Ltd UK</td>
			<td style="width:119px;">ACE-04-CC</td>
			<td>4-wells</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Chambers</td>
			<td style="width:428px;">Cell Projects Ltd UK</td>
			<td style="width:119px;">ACE-08-CC</td>
			<td>8-wells</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Lucifer Yellow</td>
			<td style="width:428px;">Cell Projects Ltd UK</td>
			<td style="width:119px;">ACE-25-LY</td>
			<td>High purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:179px;">CelTak</td>
			<td style="width:428px;">BD Biosciences</td>
			<td style="width:119px;">354240</td>
			<td>Cell and tissue adhesive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Fibronectin</td>
			<td style="width:428px;">Sigma Aldrich</td>
			<td style="width:119px;">F1141</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Collagen</td>
			<td style="width:428px;">BD Biosciences</td>
			<td style="width:119px;">354236</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Poly-Lysine</td>
			<td style="width:428px;">Sigma Aldrich</td>
			<td style="width:119px;">P8920</td>
			<td></td>
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a functional assay for gap junctional examination; electroporation of adherent cells on indium-tin oxide

In this technique, cells are cultured on a glass slide that is partly coated with indium-tin oxide (ITO), a transparent, electrically conductive material. A variety of molecules, such as peptides or oligonucleotides can be introduced into essentially 100% of the cells in a non-traumatic manner.&#160; Here, we describe how it can be used to study intercellular, gap junctional communication. Lucifer yellow penetrates into the cells when an electric pulse, applied to the conductive surface on which they are growing, causes pores to form through the cell membrane. This is electroporation. Cells growing on the nonconductive&#160;glass surface immediately adjacent to the electroporated region do not take up Lucifer yellow by electroporation but do acquire the fluorescent dye as it is passed to them via gap junctions that link them to the electroporated cells. The results of the transfer of dye from cell to cell can be observed microscopically under fluorescence illumination. This technique allows for precise quantitation of gap junctional communication. In addition, it can be used for the introduction of peptides or other non-permeant molecules, and the transfer of small electroporated peptides via gap junctions to inhibit the signal in the adjacent, non-electroporated cells is a powerful demonstration of signal inhibition.

Abbildung 2 zeigt Rattenleberzellen epithelialen T51B 22, mit LY elektroporiert und unter Fluoreszenz (Panel A und B) fotografiert oder Phasenkontrast-(C) Beleuchtung, nach Fixierung und Waschen. In Abbildung A ist die Kante des elektroporiert Bereich rot markiert. Die Steigung der Fluoreszenz rechts von der roten Linie zeigt Übertragung über Gap Junctions. In 3A und 3B ist die Quantifizierung von Gap Junction-Kommunikation gezeigt: Die Zellen auf den Rand ...

Watch this Scientific Journal Video about A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide at JoVE.com

A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide

This presentation demonstrates a method whereby electroporation of adherent, cultured cells is used for the study of intercellular, junctional communication, while the cells grow on a slide coated with conductive and transparent indium-tin oxide.

Ein Funktionstest für Gap Junction-Prüfung; Elektroporation von adhärenten Zellen auf Indium-Zinn-Oxid

In this technique, cells are cultured on a glass slide that is partly coated with indium-tin oxide (ITO), a transparent, electrically conductive material. ...

a-functional-assay-for-gap-junctional-examination-electroporation

Research

JoVE Journal

Biology

9.8K Aufrufe.  Queen's University. This presentation demonstrates a method whereby electroporation of adherent, cultured cells is used for the study of intercellular, junctional communication, while the cells grow on a slide coated with conductive and transparent indium-tin oxide.

Serie: A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide

Patterning Cells on Optically Transparent Indium Tin Oxide Electrodes

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular constructs serving as in vitro mimics of native tissues.  In this study, photolithography and wet etching techniques were used to fabricate individually addressable indium tin oxide (ITO) electrodes on glass substrates.  The glass substrates containing ITO microelectrodes were modified with poly(ethylene glycol) (PEG) silane to make them protein and cell resistive.  Presence of insulating PEG molecules on the electrode surface was verified by cyclic voltammetry employing potassium ferricyanide as a redox reporter molecule.  Importantly, the application of reductive potential caused desorption of the PEG layer, resulting in regeneration of the conductive electrode surface and appearance of typical ferricyanide redox peaks.    Application of reductive potential also corresponded to switching of ITO electrode properties from cell non-adhesive to cell-adhesive. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.  Micropatterning of several cell types was demonstrated on these substrates.   In the future, the control of the biointerfacial properties afforded by this method will allow to engineer cellular microenvironments through the assembly of three or more cell types into a precise geometric configuration on an optically transparent substrate.

Non-fouling PEG silane monolayer was desorbed from individually addressable ITO electrodes on glass by application of a reductive potential. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.

Patterning Cells auf optisch transparenten Indium-Zinn-Oxid-Elektroden

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular ...

Forschung

Biologie

Labeling hESCs and hMSCs with Iron Oxide Nanoparticles for Non-Invasive in vivo Tracking with MR Imaging

In recent years, stem cell research has led to a better understanding of developmental biology, various diseases and its potential impact on regenerative medicine. A non-invasive method to monitor the transplanted stem cells repeatedly in vivo would greatly enhance our ability to understand the mechanisms that control stem cell death and identify trophic factors and signaling pathways that improve stem cell engraftment. MR imaging has been proven to be an effective tool for the in vivo depiction of stem cells with near microscopic anatomical resolution. In order to detect stem cells with MR, the cells have to be labeled with cell specific MR contrast agents. For this purpose, iron oxide nanoparticles, such as superparamagnetic iron oxide particles (SPIO), are applied, because of their high sensitivity for cell detection and their excellent biocompatibility. SPIO particles are composed of an iron oxide core and a dextran, carboxydextran or starch coat, and function by creating local field inhomogeneities, that cause a decreased signal on T2-weighted MR images. This presentation will demonstrate techniques for labeling of stem cells with clinically applicable MR contrast agents for subsequent non-invasive in vivo tracking of the labeled cells with MR imaging.

For the evaluation of new stem cell therapies it is important to non-invasively track the injected cells in vivo. This video will show you how to label human mesenchymal and embryonic stem cells with iron oxide based contrast agents in vivo for subsequent MR imaging in vivo.

Labeling hESCs und hMSCs mit Eisenoxid-Nanopartikel für Non-Invasive in vivo-Tracking mit MR-Bildgebung

In recent years, stem cell research has led to a better understanding of developmental biology, various diseases and its potential impact on regenerative ...

In utero and ex vivo Electroporation for Gene Expression in Mouse Retinal Ganglion Cells

The retina and its sole output neuron, the retinal ganglion cell (RGC), comprise an excellent model in which to examine biological questions such as cell differentiation, axon guidance, retinotopic organization and synapse formation[1]. One drawback is the inability to efficiently and reliably manipulate gene expression in RGCs in vivo, especially in the otherwise accessible murine visual pathways. Transgenic mice can be used to manipulate gene expression, but this approach is often expensive, time consuming, and can produce unwanted side effects. In chick, in ovo electroporation is used to manipulate gene expression in RGCs for examining retina and RGC development. Although similar electroporation techniques have been developed in neonatal mouse pups[2], adult rats[3], and embryonic murine retinae in vitro[4], none of these strategies allow full characterization of RGC development and axon projections in vivo. To this end, we have developed two applications of electroporation, one in utero and the other ex vivo, to specifically target embryonic murine RGCs[5, 6]. 
With in utero retinal electroporation, we can misexpress or downregulate specific genes in RGCs and follow their axon projections through the visual pathways in vivo, allowing examination of guidance decisions at intermediate targets, such as the optic chiasm, or at target regions, such as the lateral geniculate nucleus. Perturbing gene expression in a subset of RGCs in an otherwise wild-type background facilitates an understanding of gene function throughout the retinal pathway. Additionally, we have developed a companion technique for analyzing RGC axon growth in vitro. We electroporate embryonic heads ex vivo, collect and incubate the whole retina, then prepare explants from these retinae several days later. Retinal explants can be used in a variety of in vitro assays in order to examine the response of electroporated RGC axons to guidance cues or other factors. In sum, this set of techniques enhances our ability to misexpress or downregulate genes in RGCs and should greatly aid studies examining RGC development and axon projections.

In utero and ex vivo Electroporation for Gene Expression in Mouse Retinal Ganglion Cells

Here we present two techniques for manipulating gene expression in murine retinal ganglion cells (RGCs) by in utero and ex vivo electroporation. These techniques enable one to examine how alterations in gene expression affect RGC development, axon guidance, and functional properties.

In utero und ex vivo Elektroporation für die Genexpression in Maus retinalen Ganglienzellen

The retina and its sole output neuron, the retinal ganglion cell (RGC), comprise an excellent model in which to examine biological questions such as cell ...

In situ Subcellular Fractionation of Adherent and Non-adherent Mammalian Cells

Protein function is intimately coupled to protein localization. Although some proteins are restricted to a specific location or subcellular compartment, many proteins are present as a freely diffusing population in free exchange with a sub-population that is tightly associated with a particular subcellular domain or structure. In situ subcellular fractionation allows the visualization of protein compartmentalization and can also reveal protein sub-populations that localize to specific structures. For example, removal of soluble cytoplasmic proteins and loosely held nuclear proteins can reveal the stable association of some transcription factors with chromatin. Subsequent digestion of DNA can in some cases reveal association with the network of proteins and RNAs that is collectively termed the nuclear scaffold or nuclear matrix. 
Here we describe the steps required during the in situ fractionation of adherent and non-adherent mammalian cells on microscope coverslips. Protein visualization can be achieved using specific antibodies or fluorescent fusion proteins and fluorescence microscopy. Antibodies and/or fluorescent dyes that act as markers for specific compartments or structures allow protein localization to be mapped in detail. In situ fractionation can also be combined with western blotting to compare the amounts of protein present in each fraction. This simple biochemical approach can reveal associations that would otherwise remain undetected.

In situ Subcellular Fractionation of Adherent and Non-adherent Mammalian Cells

In situ subcellular fractionation of mammalian cells on microscope coverslips allows the visualisation of protein localisation.

In situ subzelluläre Fraktionierung von adhärenten und nicht adhärenten Säugetierzellen

Protein function is intimately coupled to protein localization. Although some proteins are restricted to a specific location or subcellular compartment, ...

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying potassium (referred to as GIRK) channels, which are important for regulating the excitability of neurons. There are four different mammalian GIRK channel subunits (GIRK1-GIRK4) - we focus on GIRK2 because it forms a homotetramer. Stimulation of different types of G protein-coupled receptors (GPCRs), such as the muscarinic receptor (M2R), leads to activation of GIRK channels. Alcohol also directly activates GIRK channels. We will show how to mutate one amino acid by specifically changing one or more nucleotides in the cDNA for the GIRK channel. This mutated cDNA sequence will be amplified in bacteria, purified, and the presence of the point mutation will be confirmed by DNA sequencing. The cDNAs for the mutated and wild-type GIRK channels will be transfected into human embryonic kidney HEK293T cells cultured in vitro. Lastly, whole-cell patch-clamp electrophysiology will be used to study the macroscopic potassium currents through the ectopically expressed wild-type or mutated GIRK channels. In this experiment, we will examine the effect of a L257W mutation in GIRK2 channels on M2R-dependent and alcohol-dependent activation.

We will demonstrate how to study the effect of a single point mutation on the function of an ion channel.

Mutagenese und funktionale Analyse von Ionenkanälen heterolog in Säugerzellen exprimierten

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying ...

Clonogenic Assay: Adherent Cells

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. Apart from documenting the method, the initial landmark study generated the first radiation-dose response curve for X-ray irradiated mammalian (HeLa) cells in culture1. Basically, the clonogenic assay enables an assessment of the differences in reproductive viability (capacity of cells to produce progeny; i.e. a single cell to form a colony of 50 or more cells) between control untreated cells and cells that have undergone various treatments such as exposure to ionising radiation, various chemical compounds (e.g. cytotoxic agents) or in other cases genetic manipulation. The assay has become the most widely accepted technique in radiation biology and has been widely used for evaluating the radiation sensitivity of different cell lines. Further, the clonogenic assay is commonly used for monitoring the efficacy of radiation modifying compounds and for determining the effects of cytotoxic agents and other anti-cancer therapeutics on colony forming ability, in different cell lines. A typical clonogenic survival experiment using adherent cells lines involves three distinct components, 1) treatment of the cell monolayer in tissue culture flasks, 2) preparation of single cell suspensions and plating an appropriate number of cells in petri dishes and 3) fixing and staining colonies following a relevant incubation period, which could range from 1-3 weeks, depending on the cell line. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cell lines with the use of an immortalized human keratinocyte cell line (FEP-1811)2. Also, our aims are to describe common features of clonogenic assays including calculation of the plating efficiency and survival fractions after exposure of cells to radiation, and to exemplify modification of radiation-response with the use of a natural antioxidant formulation.

The applicability of the clonogenic assay for evaluating reproductive viability has been established for more than 50 years. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cells.

Klonogene Test: adhärenter Zellen

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. ...

Identifying Targets of Human microRNAs with the LightSwitch Luciferase Assay System using 3'UTR-reporter Constructs and a microRNA Mimic in Adherent Cells

MicroRNAs (miRNAs) are important regulators of gene expression and play a role in many biological processes. More than 700 human miRNAs have been identified so far with each having up to hundreds of unique target mRNAs. Computational tools, expression and proteomics assays, and chromatin-immunoprecipitation-based techniques provide important clues for identifying mRNAs that are direct targets of a particular miRNA. In addition, 3'UTR-reporter assays have become an important component of thorough miRNA target studies because they provide functional evidence for and quantitate the effects of specific miRNA-3'UTR interactions in a cell-based system. To enable more researchers to leverage 3'UTR-reporter assays and to support the scale-up of such assays to high-throughput levels, we have created a genome-wide collection of human 3'UTR luciferase reporters in the highly-optimized LightSwitch Luciferase Assay System. The system also includes synthetic miRNA target reporter constructs for use as positive controls, various endogenous 3'UTR reporter constructs, and a series of standardized experimental protocols.
Here we describe a method for co-transfection of individual 3'UTR-reporter constructs along with a miRNA mimic that is efficient, reproducible, and amenable to high-throughput analysis.

Identifying Targets of Human microRNAs with the LightSwitch Luciferase Assay System using 3&#039;UTR-reporter Constructs and a microRNA Mimic in Adherent Cells

MicroRNAs (miRNAs) are important regulators of gene expression and have been shown to play a role in numerous biological processes. To better understand miRNA-UTR interactions, we have created a genome-wide collection of 3 UTR luciferase reporters paired with a novel luciferase gene and assay reagent, the LightSwitch system.

Identifizierung von Zielen für Menschenrechte microRNAs mit dem LightSwitch Luciferase Assay System mit 3&#39;UTR-Reporter-Konstrukte und eine microRNA Mimic in adhärenter Zellen

MicroRNAs (miRNAs) are important regulators of gene expression and play a role in many biological processes.  More than 700 human miRNAs have been ...

Examination of Drosophila Larval Tracheal Terminal Cells by Light Microscopy

Cell shape is critical for cell function. However, despite the importance of cell morphology, little is known about how individual cells generate specific shapes. Drosophila tracheal terminal cells have become a powerful genetic model to identify and elucidate the roles of genes required for generating cellular morphologies. Terminal cells are a component of a branched tubular network, the tracheal system that functions to supply oxygen to internal tissues. Terminal cells are an excellent model for investigating questions of cell shape as they possess two distinct cellular architectures. First, terminal cells have an elaborate branched morphology, similar to complex neurons; second, terminal cell branches are formed as thin tubes and contain a membrane-bound intracellular lumen. Quantitative analysis of terminal cell branch number, branch organization and individual branch shape, can be used to provide information about the role of specific genetic mechanisms in the making of a branched cell. Analysis of tube formation in these cells can reveal conserved mechanisms of tubulogenesis common to other tubular networks, such as the vertebrate vasculature. Here we describe techniques that can be used to rapidly fix, image, and analyze both branching patterns and tube formation in terminal cells within Drosophila larvae. These techniques can be used to analyze terminal cells in wild-type and mutant animals, or genetic mosaics. Because of the high efficiency of this protocol, it is also well suited for genetic, RNAi-based, or drug screens in the Drosophila tracheal system.

Examination of Drosophila Larval Tracheal Terminal Cells by Light Microscopy

Here, we present a method for light microscopy analysis of tracheal terminal cells in Drosophila larvae. This method allows for quick examination of branch and lumen morphology in whole animals and would be useful for analysis of individual mutants or screens for mutations affecting terminal cell development.

Prüfung der<em&gt; Drosophila</em&gt; Larven Tracheal Terminal-Cells durch Lichtmikroskopie

Cell shape is critical for cell function. However, despite the importance of cell morphology, little is known about how individual cells generate specific ...

Measurement and Analysis of Extracellular Acid Production to Determine Glycolytic Rate

Extracellular measurement of oxygen consumption and acid production is a simple and powerful way to monitor rates of respiration and glycolysis1. Both mitochondrial (respiration) and non-mitochondrial (other redox) reactions consume oxygen, but these reactions can be easily distinguished by chemical inhibition of mitochondrial respiration. However, while mitochondrial oxygen consumption is an unambiguous and direct measurement of respiration rate2, the same is not true for extracellular acid production and its relationship to glycolytic rate 3-6. Extracellular acid produced by cells is derived from both lactate, produced by anaerobic glycolysis, and CO2, produced in the citric acid cycle during respiration. For glycolysis, the conversion of glucose to lactate- + H+ and the export of products into the assay medium is the source of glycolytic acidification. For respiration, the export of CO2, hydration to H2CO3 and dissociation to HCO3- + H+ is the source of respiratory acidification. The proportions of glycolytic and respiratory acidification depend on the experimental conditions, including cell type and substrate(s) provided, and can range from nearly 100% glycolytic acidification to nearly 100% respiratory acidification 6. Here, we demonstrate the data collection and calculation methods needed to determine respiratory and glycolytic contributions to total extracellular acidification by whole cells in culture using C2C12 myoblast cells as a model.

Glycolysis is a defining metabolic marker in multiple biological systems. Monitoring glycolysis by measuring the extracellular flux of H+ is common, but requires correction to be quantitative and unambiguous. Here, we demonstrate how to gather and correct extracellular flux data to distinguish between respiratory and glycolytic sources of extracellular acidification.

Messung und Analyse von extrazellulären Säureproduktion zu ermitteln glykolytischen Rate

Extracellular measurement of oxygen consumption and acid production is a simple and powerful way to monitor rates of respiration and glycolysis1. Both ...

Nephrotoxin Microinjection in Zebrafish to Model Acute Kidney Injury

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid decline in renal function and development of the clinical syndrome known as acute kidney injury (AKI). Pharmacological agents used to treat medical circumstances ranging from bacterial infection to cancer, when administered individually or in combination with other drugs, can initiate AKI. Zebrafish are a useful animal model to study the chemical effects on renal function in vivo, as they form an embryonic kidney comprised of nephron functional units that are conserved with higher vertebrates, including humans. Further, zebrafish can be utilized to perform genetic and chemical screens, which provide opportunities to elucidate the cellular and molecular facets of AKI and develop therapeutic strategies such as the identification of nephroprotective molecules. Here, we demonstrate how microinjection into the zebrafish embryo can be utilized as a paradigm for nephrotoxin studies.

Renal injuries incurred from nephrotoxins, which include drugs ranging from antibiotics to chemotherapeutics, can result in complex disorders whose pathogenesis remains incompletely understood. This protocol demonstrates how zebrafish can be used for disease modeling of these conditions, which can be applied to the identification of renoprotective measures.

Nephrotoxin Mikroinjektion in Zebrabärbling akuten Nierenschädigung zu Modell

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid ...