Wir möchten Andrea Kremsreiter für hervorragende technische Unterstützung danken. Madison - Die Arbeit in unserem Labor wird von NIH GM096088 und Vilas Vertrauen der Universität von Wisconsin unterstützt.

1. Hefe Luminometrie Methoden Verwenden BYYT Stamm von Saccharomyces cerevisiae. Es ist ein yvc1-TOK1-Derivat von BY4741 (Mata, ura3D0, his3D1, leu2D0, lys2D0, yvc1 :: HIS3, TOK1 :: kanMX4). Trans Zellen mit den leu-wählbar Aequorin-exprimierenden Plasmid pEVP1/Aeq und ura wählbare rat-TRPV4-exprimierenden Plasmid p416GPDV4, wie in Batiza et al. Loukin 26 und et al. Beschrieben 24 Verwenden Sie Standard-Methoden von Plasmid-Bau und Umbau 27 . Hefestamm und Plasmide sind auf Anfrage erhältlich. <ol><li> 2 ml Kultur von Hefe-Zellen über Nacht auf post-logarithmischen Phase in ein 30 º C-Schüttler in leu-ura-&quot;DCD&quot; Dropout-Medium 28 (a Sulfat abgereicherte Variante der CMD-Leu-ura-Medium 29), ergänzt mit 1 M Sorbitol . Beimpfen von 200 &amp;mgr; l dieser Kultur in 1,8 ml frisches Medium mit 2 &amp;mgr; M des luciferi ergänztn Coelenterazins. Wachsen in der Dunkelheit bei Raumtemperatur für weitere 24 h ohne Schütteln. </li><li> Messung der Osmolarität der Kultur (typischerweise bei 1400 mOsM) und andere Lösungen (unten) mit Hilfe eines Dampfdruck-Osmometer. </li><li> Aliquot 20 ml frisches Kultur in ein 12 mm Luminometerröhrchen für ein einzelnes Rohr Luminometer. </li><li> Für die hypotonischen Schock, 200 ul einer Lösung, enthaltend 25 mM NaEGTA (pH 7,2) oder Namen (pH 7,2) und 500-100 mM NaCl (insgesamt Osmolarität 1,200-400 mOsM), je nach dem Grad der gewünschten Schlag. Die Lumineszenz vor kontinuierlich zu überwachen und mindestens 120 Sekunden nach dem osmotischen downshock, unterbrochen nur von der kurzen Verdünnungsbetrieb. Registrieren Luminometer Ausgang auf einem Desktop-Computer als relative Lumineszenz-Einheiten (RUL). </li></ol> Obwohl nicht für die Untersuchung von transgenen TRPV4 haben wir eine Variante des obigen Protokolls in einem automatisierten System verwendet werden, um die Antworten von einer Vielzahl von Hefestämmen zu untersuchen. Studie of die Antworten auf die hypo-30 oder 31 hyperosmotische Reize der Hefe deletome (die Sammlung von 4.906 Hefe-Single-Gen Deletanten) mit Hilfe eines Mikroplatten-Luminometer und mit entsprechender Software ausgewertet war erfolgreich. 2. und 3. Eizellenelektrophysiologie Methoden Elektrophysiologie hat grundlegende Methoden 32. PCR verstärken die offenen Leserahmen von Wildtyp-oder mutierten TRPV4 mit High-Fidelity-Polymerase und PfuUtra in pGH19 33 integriert. Dies erfordert eine genaue Insertion des ORFs zwischen den 5 &#39;und 3&#39;-UTR des Xenopus-β-Globin-Gens und stromabwärts von einem T7-RNA-Polymerase-Promotor. Linearisieren der Konstruktion stromabwärts der 3&#39;-UTR und als Template in einem in vitro T7-RNA-Polymerase-Reaktion verwendet. Verwenden Sie Standard-molekularbiologische Techniken 34. Verwenden Stadium V-VI Oozyten von X. laevis. Tierhaltung, Teil ovariectomy, defolliculation und Dotter Umschlag Entfernung folgen Standardverfahren 32,33,35. Inject 2-40 ng cRNA-Lösung pro Eizelle mit einem Drummond Nanoinject II Automatik Mikroinjektor. Injizieren ~ 30 Oozyten für jeden Satz von Experimenten. Nach TRPV4-cRNA Injektion, Inkubation der Oozyten in der ND96 Medium mit Gentamicin (100 ug / ml) und 1 uM Ruthenium Red 14. 2. Zweielektroden-Spannungsklemmen <ol><li> Ziehen Borosilikatglas Aufnahme Präzisionspipetten von Einweg-Mikropipetten 100 ul einzeln mit einer Pipette Magnet. </li><li> Ziehen sowohl Spannungs-Mess-und Strominjektionspipette Elektroden werden gezogen, um eine Spitzenöffnung von ~ 1 Mikrometer Durchmesser haben. </li><li> Backfill-Elektroden mit 2 M KCl was 0,1-0,2 mOhm Widerstand. Montieren Sie sie auf HS2A headstages, die zusammen mit einem VG-2Ax100 virtuelle geerdete Bad Klemme, werden zu einem Verstärker Geneclamp 500 Schnittstelle über eine Digidata 1440 Digitalisierer verbunden. Erwerben<html> Daten mit pClamp10 Software. </li><li> Zeigen die Eizelle in einem 1 ml Bad in einer vorgefertigten Kunststoffkammer auf der Stufe eines Binokular mit 20-facher Vergrößerung montiert getestet werden. Die Badlösung virtuell geerdet durch eine 3 M KCl-Agar-Brücke und einem chlorierten Silberdraht in der Nähe der Eizelle eingebracht und an einem VG-2A virtuellen Masse Stufe verbunden. </li><li> Konstruieren Sie die Kammer für die kontinuierliche Perfusion mit Kunststoffschläuche als Ein-und Auslauf Lösung. Verbinden der Einlaßleitung ist mit einem vorgefertigten Perfusionssystem, die eine Mannigfaltigkeit von sechs 50-ml-Spritze Schalen, jede mit einer anderen Lösung gefüllt ist, verbunden. Gravity Feed Raten einer beliebigen Lösung gesteuert wird, um ~ 3.2 ml / min mit &quot;Keck&quot; Rampe Schellen an den Schläuchen. </li><li> Montieren Sie beide Elektroden mit ihren headstages auf Mikromanipulatoren. Führen Elektrodendurchführungen der Eizelle durch Mikromanipulation. </li></ol> 3. Patch-Clamp-Untersuchung der Direkt Mechanosensitivität &quot;&gt; Die grundlegenden Methoden der Patch-Clamp-Pipette einschließlich Vorbereitung, GOhm-Dichtung Bildung und die Bildung von Ein-Zelle herausgeschnitten oder Betriebsarten sind die in Hamill et al. Conn 36 und 32. <ol><li> Füllen Borosilikat-Glaspipetten mit einem ~ 1 um Durchmesser Öffnung an der Spitze (Blasenzahl 5-6) mit 98 mM KCl, 1 mM MgCl 2 und 10 mM K +-HEPES, pH 7,2. </li><li> Befestigen der Patch-Clamp-Pipette durch einen Kunststoffschlauch mit einer 5 ml Spritze durch eine T-Verbindung, die auch mit einem Manometer. Verwenden Sie einen Computer, um sowohl die Elektrode und die Manometer Ausgänge verarbeiten. Erwerben Daten bei 10 kHz, und spielen dann wieder durch einen achtpoligen Bessel-Filter bei 1 kHz für die Analyse. </li><li> Verschiedenen Patches aus demselben Eizelle wiederholt ausgeschnitten werden. Diese Praxis macht die Untersuchung der molekularen TRPV4 Tätigkeit effizienter und zuverlässiger. </li></ol>

<ol>
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Die Autoren erklären, dass sie keine finanziellen Interessen konkurrieren.

Wie in der Einleitung erwähnt, die häufig verwendet, um Funktionen zu studieren TRPV4 Methoden führte manchmal in Widersprüche und Kontroversen. Die zwei Sätze von hier beschriebenen Methoden bieten einige Vorteile und kann die vorhandenen Methoden zu ergänzen. Während wir nur die Studien zu TRPV4 beschreiben, können die Verfahren auch auf andere Ionenkanäle als auch studieren. 1. Hefe Luminometrie Methoden Angehende Hefe hat eine native Ca 2 +-Einstr...

TRP (transient receptor Potenziale) aus sieben Unterfamilien der Kationenkanäle, 1,2 sensorischen Funktionen dienen. Bei Säugetieren TRPV die Vanilloid Unterfamilie der TRP, sechs Sorten. TRPV4 (Typ 4) 3,4 reagiert auf Wärme, bestimmte Chemikalien, osmotische Schwellung oder Scherbeanspruchung. Das TRPV4-Gens wurde wiederholt von Kandidaten-Gen und / oder Expression Klonen 5-8 isoliert. Die letztere Methode folgte die Antwort des Genprodukts zu Hypo-Osmolarität. TRPV4 in fast allen Organen und Funktionen in der Entwicklung, Physiologie und Pathologie von vielen unterschiedlichen Zelltypen 3,4 ausgedrückt. Auffällig sind die&gt; 50 menschliche autosomal dominant TRPV4 Mutationen, wodurch periphere Neuropathien und / oder Skelettdysplasien (Anomalien in der Skelettentwicklung) 11.09. Die Skelettdysplasien reichen von leichten brachyomia Typ 3 (Typ-3-Zwergwuchs), Dysplasie, spondylometaphysäre Kozlowski-Typ, um SeveWieder Dysplasien, einige verursachen neonatalen oder embryonale Tod. Obwohl alle Arten der Mechanismen möglich scheint, erklärt keiner die Vielfalt, Komplexität, Variabilität und gelegentliche Überschneidungen dieser Krankheiten 4. Wie andere TRP-Kanäle 1, ist TRPV4 ein Tetramer. In Ratten-oder Menschen TRPV4 wird jede Untereinheit von 871 Resten bestand. Zentrales Element ist ein sechs Transmembran-Helices (S1-S6), die geeignet in einer Weise ähnlich zu spannungsabhängigen K +-Kanäle angeordnet sind. Dort S1 bis S4 bilden eine Umfangs Domäne und die S5 und S6 bilden die Permeation Porendomäne. Zwischen S5 und S6 von TRPV4 ist eine kurze Porenhelix gefolgt von der Sequenz LDLFKLTIGMGDL, von denen vier vermutlich konvergieren, um die Kationenfilter bilden. Die 470-Rest N-terminalen cytoplasmatischen Segment enthält 6 Ankyrin Wiederholungen bekannt, Proteine ​​oder kleine Liganden zu binden. Die C-terminale 152-Rückstand cytoplasmatischen Segment eine Calmodulin-Bindungssequenz unter anderen möglichen Seiten, ot bindenihr Elemente 3. TRPV4 ist ein Kationenkanal, der im Wesentlichen schließt Anionen ein. Während seiner physiologischen Funktion ist um Stimuli an Ca 2 +-Einstrom zu transduzieren, ist es auch durchlässig für andere Kationen mit einer Eisenman-Sequenz IV Durchlässigkeit, bei einer Begünstigung zweiwertiger P Ca: P Na ~ 7 12. Einzelkanalleitfähigkeit richtet bei ~ 90 pS nach außen und nach innen ~ 40 pS 6,13,14. Heterolog exprimiert Strom (unten) kann durch hypo-osmotischen Schwellung, Schubspannung, Wärme oder 15 aktiviert werden. Es wird auch von mehrfach ungesättigten Fettsäuren 16,17 und das synthetische Ester phorbal 4αPDD 18 aktiviert. Derzeit ist die potenter Agonist GSK1016790A 19 und Antagonist GSK2193874, wirksam bei 10 -9 bis 10 -8 M-20, die beide von Hochdurchsatz-, Kleinmolekülbild entdeckt. Zwei Schlüsselbereiche der Forschung zu bleiben verwirrend TRPV4: (1) Schon als TRPV4 ist weitgehend für seine Mechanosensitivität studiert, ist seine molekulare Basis umstritten. Ein Modell beschreibt Hypo-Osmolarität irgendwie aktiviert Phospholipase A2 (PLA2), die mehrfach ungesättigte Fettsäure (PUFA) Arachidonsäure (AA), die umgewandelt Säure (EET) von einem Epoxygenase Epoxyeicosatrienoide ist zu produzieren, und die Bindung von EET aktiviert TRPV4 16, 17. Doch selbst TRPV4 wurde gezeigt, direkt an Membran Strecke 14 (unten) zu reagieren, um eine einfachere Erklärung. (2) Die TRPV4 Mutante Pathologien sind verwirrend. Die Grundlage, muss man wissen, ob die Erkrankungen, die durch den Verlust, der Verringerung oder die Erhöhung der Kanalaktivitäten. Auch hier ist die Literatur alles andere als klar. Während mehrere Skelett-Dysplasie-Allele wurde berichtet, dass höhere Aktivitäten haben, (Gain-of-function, GOF) 4,21, mehrere wurden gemeldet, Aktivitäten (Loss-of-function, LOF) 10,22 reduziert. Eine systematische Untersuchung von 14 Allele gefunden, sie zuAlle GOF werden Mutationen (unten) 23. Die Behauptung, dass einige sind LOFs scheint den Phänotyp des TRPV4-/ widersprechen - Knockout-Maus, die lebensfähig oder fruchtbar sind, mit nur geringfügigen Mängeln, trotz einem vollständigen Verlust des TRPV4-Funktion. Ein Teil dieser Kontroversen methodische Herkunft. Laboratories verwenden unterschiedliche Methoden oder Varianten einer Methode und verwenden unterschiedliche Beurteilungsstandards. Am häufigsten wird TRPV4 transient in kultivierten Säugerzellen exprimiert (HEK, CHO, HeLa) und der Anstieg des Innen [Ca 2 +] auf Agonisten oder hypotonen Stimulation mit Ca 2 +-sensitiven Fluoreszenzfarbstoff Fura-2 eingetragen. Die übermäßige Abhängigkeit von dieser fluorimetrischen Test ist kritisiert worden, ein. Das Expressionsniveau in verschiedenen Populationen, die Verteilung darin sowie die wirksame Farbstoffkonzentration, müssen kontrolliert und dokumentiert werden. Zuverlässiger ist die direkte elektrophysiologische Untersuchungen. Auch dieser, wie commonly praktiziert wird, ist auch nicht ohne Probleme. Da die Expressionsmengen in einzelnen kultivierten Zellen sind schwierig zu steuern, Ganzzellströme großen Schwankungen. Da ferner die Ströme klein sind, werden zuverlässige Statistiken müssen auf große Stichproben, die oft nicht praktisch verlassen. Patch-Clamp-Untersuchungen nur selten durchgeführt. Einige dieser Aufnahmen zeigen Gruppen von Aktivität Bursts statistische Auswertung anspruchs 16,17 zu machen. Um die molekularen Mechanosensitivität besser zu verstehen, haben wir zwei weitere Systeme entwickelt, um TRPV4 zu untersuchen. (1) Um TRPV4 weg von seiner üblichen Säugetier Partner zu isolieren, haben wir Ratten TRPV4 in Bäckerhefe 24 ausgedrückt. Die funktionelle Expression von TRPV4 in diesem evolutionär entfernten Zusammenhang zeigte, dass es noch osmotische Kraft zu reagieren, ohne seinen üblichen Partnern. Da Hefe macht keine PUFA wie AA oder EET, und sein Genom hat keine PLA2 oder Epoxygenase Gene, die diese expression zeigt auch, dass sie nicht erforderlich sind, um für TRPV4 Kraft zu spüren. Mit TRPV4 in den molekularbiologisch am ehesten zugänglich Eukaryonten ermöglicht auch eine effiziente zukunfts oder Reverse-25 genetische Manipulationen. (2) Für umfassende Analysen der biophysikalischen TRPV4, ausgedrückt wir TRPV4 in Xenopus-Oozyten. Anders als kultivierte Zellen, die Unter nA nA (10 -10 bis 10 -9 A) Ströme ergeben, eine Oozyte exprimiert Ströme in uA ist (10 -6 bis 10 -4 A). Viel größere Rauschsignal über eine bessere Quantifizierung und selbstbewusster Vergleich. TRPV4, so ausgedrückt, kann auch als Einzelmoleküle unter Verwendung eines Patch-Clamp sucht werden. Eine einzige Eizelle ermöglicht wiederholte Patch Probenahme, wieder machen Quantifizierung zuverlässiger. Solche Studien haben gezeigt, dass TRPV4 Kanal selbst kann direkt durch Membran Strecke Kraft 14 aktiviert werden. Die Analysen zeigten, dass 14-Dysplasie repräsentativen Skelett Allele sind alle gain-of-function-Mutationen. Ferner ist die degree des konstitutiven Ca 2 + Leck Parallelen der Schwere der Erkrankungen der Skelett 23. Aufgrund ihrer Neuheit und Nützlichkeit sind die detaillierten Verfahren dieser beiden Methoden hier versammelt, um Wiederholungen in Zukunft Forschung auf TRPV4 oder ähnliche Kanäle ermöglichen.

<table border="0" cellpadding="0" cellspacing="0" width="595">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Vapor Pressure Osmometer</td>
			<td style="width:93px;">Wescor</td>
			<td style="width:119px;">Wescor 5500</td>
			<td style="width:167px;">Logan, UT, USA</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Sirius Single Tube Luminometer </td>
			<td style="width:93px;">Titertek-Berhold</td>
			<td style="width:119px;">Sirius </td>
			<td>Huntsville, LA, USA</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Microplate luminometer</td>
			<td style="width:93px;">Titertek-Berthold </td>
			<td style="width:119px;">Mithras LB940</td>
			<td>Huntsville, LA, USA</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Luminometry software</td>
			<td style="width:93px;">Titertek-Berthold</td>
			<td style="width:119px;">MikroWin2000</td>
			<td>Huntsville, LA, USA</td>
		</tr>
		<tr height="210">
			<td height="210" style="height:210px;width:216px;">Patch clamp and software</td>
			<td style="width:93px;">Axon Instrument</td>
			<td style="width:119px;">HS2A headstage, VG-2Ax100 virtual grounded bath clamp, GeneClamp 500 amplifier, digidata 1440 digitizer, pClamp10 software </td>
			<td>Union City, CA, USA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">manometer</td>
			<td style="width:93px;">Bio-Tec</td>
			<td style="width:119px;"> </td>
			<td>Winooski, VT, USA</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Pipet puller</td>
			<td style="width:93px;">Sutter Instrument Co</td>
			<td style="width:119px;">Model P-97</td>
			<td>Novata, CA, USA</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Microinjector</td>
			<td style="width:93px;">Drummond Scientific</td>
			<td style="width:119px;">Nanoinject II</td>
			<td>Broomall, PA, USA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Material:</td>
			<td style="width:93px;"> </td>
			<td style="width:119px;"> </td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">luciferin coelenterazine</td>
			<td style="width:93px;">Invitrogen</td>
			<td style="width:119px;"> </td>
			<td>Carlsbad, CA, USA</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">T7 RNA polymerase reaction</td>
			<td style="width:93px;">Ambion</td>
			<td style="width:119px;">mMessage mMachine</td>
			<td>Austin, TX, USA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">gentamicin</td>
			<td style="width:93px;">Sigma</td>
			<td style="width:119px;"> </td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">ruthenium red </td>
			<td style="width:93px;">Sigma</td>
			<td style="width:119px;"> </td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">micropipets </td>
			<td style="width:93px;">Drummond</td>
			<td style="width:119px;">100 microliter micropipets</td>
			<td>Broomall, PA, USA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">high-fidelity PfuUtra polymerase </td>
			<td style="width:93px;">Stratagene</td>
			<td style="width:119px;"> </td>
			<td>La Jolla, CA, USA</td>
		</tr>
	</tbody>
</table>

yeast luminometric and xenopus oocyte electrophysiological examinations of the molecular mechanosensitivity of trpv4

TRPV4 (Transient Receptor Potentiale, Vanilloid-Familie, Typ 4) ist weit verbreitet in Wirbel Geweben exprimiert und wird von mehreren Stimuli, unter anderem durch mechanische Kräfte aktiviert. Bestimmte Mutationen verursachen TRPV4 komplexe erbliche Knochen oder neuronalen Erkrankungen in Menschen. Wildtyp-oder mutierten TRPV4 Transgene werden üblicherweise in kultivierten Säugerzellen exprimiert und durch Fura-2-Fluorometrie und Elektroden untersucht. In Bezug auf den Mechanismus der Mechanosensitivität und der molekularen Grundlagen von Krankheiten, ist die gegenwärtige Literatur verwirrend und umstritten. Um bestehende Methoden zu ergänzen, beschreiben wir zwei zusätzliche Methoden, um die molekularen Eigenschaften des TRPV4 zu untersuchen. (1) Rat TRPV4 und ein Aequorin Transgen in Hefezellen transformiert. Ein Hypo-osmtic Schock der Trans Bevölkerung ergibt eine luminometrische Signal aufgrund der Kombination von Aequorin mit Ca 2 + durch die TRPV4 Kanal veröffentlicht. Hier TRPV4 wird von seiner üblichen Säugetierpartnerproteine ​​isoliertund offenbart seine eigene Mechanosensitivität. (2) von TRPV4 cRNA in Xenopus-Oozyten injiziert. Nach einer geeigneten Inkubationszeit wird die makroskopische TRPV4 Strom mit einer Zwei-Elektroden-Spannungsklemme sucht. Der aktuelle Anstieg bei der Entfernung von inerten Osmotikums aus der Eizelle Bad ist bezeichnend für Mechanosensitivität. Die Mikroampere (10 -6 bis 10 -4 A) Ströme von Oozyten sind viel größer als die subnano zu Nanoampere (10 -10 bis 10 -9 A) Ströme aus kultivierten Zellen, was zu klareren und Quantifizierungen sicherer Abschätzungen. Mikroskopische Ströme reflektieren die Aktivitäten der einzelnen Kanalproteine ​​können auch direkt unter einer Patch-Clamp-registriert werden, auf der Zelle herausgeschnitten oder-Modus. Das gleiche Eizelle bietet mehrere Patch-Proben, die eine bessere Datenreplikation. Ansaugung zu den Patches können TRPV4 aktivieren, um direkt beurteilen Mechanosensitivität. Diese Verfahren sollten auch bei der Untersuchung anderer Arten von TRP-Kanälen sein.

In einem typischen Experiment Luminometrie, wird ein Bereich von 400-1200 mOsM hypotone unten Schocks durch Zugabe von 200 ul von Schock-Lösungen unterschiedlicher niedrigen Osmolarität zu 20 ul Kultur bei 1.400 mOsM erreicht. Die TRPV4 Aktivität ist offensichtlich, wenn die RLU der experimentellen wird, daß von zwei negativen Kontrollen verglichen: Hefezellen mit leeren p416GPDV4 Plasmid oder eine, die die TRPV4 Gen mit einer Mutation an der Ionenfilter (Fig. 1) 24 enthält, tra...

Watch this Scientific Journal Video about Yeast Luminometric and Xenopus Oocyte Electrophysiological Examinations of the Molecular Mechanosensitivity of TRPV4 at JoVE.com

Yeast Luminometric and Xenopus Oocyte Electrophysiological Examinations of the Molecular Mechanosensitivity of TRPV4

Um häufigsten verwendeten Methoden, um zu studieren TRPV4 ergänzen, werden zwei Methoden beschrieben: Seine Mechanosensitivität kann durch Ca 2 +-Aequorin Luminometrie in transgenen Hefe auf hypo-osmotischen Herausforderung untersucht werden. Es kann auch in TRPV4-RNA untersucht werden injizierten Xenopus Oocyten durch Ganzzell-Zweielektroden-Spannungsklemmen-oder Patch-Clamp in Ein-Zelle oder entfernten Modus.

Hefe und luminometrischer<em&gt; Xenopus</em&gt; Eizelle Elektrophysiologische Untersuchungen des Molecular Mechanosensitivität von TRPV4

TRPV4 (Transient Receptor Potentials, vanilloid family, type 4) is widely expressed in vertebrate tissues and is activated by several stimuli, including ...

yeast-luminometric-xenopus-oocyte-electrophysiological-examinations

Research

JoVE Journal

Biology

Yeast Luminometric and Xenopus Oocyte Electrophysiological Examinations of the Molecular Mechanosensitivity of TRPV4

10.0K Aufrufe.  University of Wisconsin – Madison.  Um häufigsten verwendeten Methoden, um zu studieren TRPV4 ergänzen, werden zwei Methoden beschrieben: Seine Mechanosensitivität kann durch Ca 2 +-Aequorin Luminometrie in transgenen Hefe auf hypo-osmotischen Herausforderung untersucht werden. Es kann auch in TRPV4-RNA untersucht werden injizierten Xenopus Oocyten durch Ganzzell-Zweielektroden-Spannungsklemmen-oder Patch-Clamp in Ein-Zelle oder entfernten Modus. 

Serie: Yeast Luminometric and Xenopus Oocyte Electrophysiological Examinations of the Molecular Mechanosensitivity of TRPV4

A Rapid Technique for the Visualization of Live Immobilized Yeast Cells

We present here a simple, rapid, and extremely flexible technique for the immobilization and visualization of growing yeast cells by epifluorescence microscopy. The technique is equally suited for visualization of static yeast populations, or time courses experiments up to ten hours in length. My microscopy investigates epigenetic inheritance at the silent mating loci in S. cerevisiae. There are two silent mating loci, HML and HMR, which are normally not expressed as they are packaged in heterochromatin. In the sir1 mutant background silencing is weakened such that each locus can either be in the expressed or silenced epigenetic state, so in the population as a whole there is a mix of cells of different epigenetic states for both HML and HMR. My microscopy demonstrated that there is no relationship between the epigenetic state of HML and HMR in an individual cell. sir1 cells stochastically switch epigenetic states, establishing silencing at a previously expressed locus or expressing a previously silenced locus. My time course microscopy tracked individual sir1 cells and their offspring to score the frequency of each of the four possible epigenetic switches, and thus the stability of each of the epigenetic states in sir1 cells. See also  Xu et al., Mol. Cell 2006.

A rapid technique for the visualization of growing immobilized yeast cells, here applied to fluorescent reporters at the silent mating loci HML and HMR

Ein schnelles Verfahren für die Visualisierung von Live-immobilisierten Hefezellen

We present here a simple, rapid, and extremely flexible technique for the immobilization and visualization of growing yeast cells by epifluorescence ...

Forschung

Biologie

Patch Clamp Recording of Ion Channels Expressed in  Xenopus Oocytes

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological measurement of single or multiple ion channels in cells. This technique can be applied to ion channels in both their native environment and expressed in heterologous cells, such as oocytes harvested from the African clawed frog, Xenopus laevis. Here, we describe the well-established technique of patch clamp recording from Xenopus oocytes. This technique is used to measure the properties of expressed ion channels either in populations (macropatch) or individually (single-channel recording). We focus on techniques to maximize the quality of oocyte preparation and seal generation. With all factors optimized, this technique gives a probability of successful seal generation over 90 percent. The process may be optimized differently by every researcher based on the factors he or she finds most important, and we present the approach that have lead to the greatest success in our hands.

This is intended as an introduction to patch clamp recording from Xenopus laevis oocytes. It covers vitelline membrane removal, formation of a gigaohm seal (gigaseal), and the optional conversion of the patch to the outside-out topology.

Patch Clamp Recording von Ionenkanälen in Xenopus Oozyten exprimiert

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological ...

Visualizing RNA Localization in Xenopus Oocytes

RNA localization is a conserved mechanism of establishing cell polarity. Vg1 mRNA localizes to the vegetal pole of Xenopus laevis oocytes and acts to spatially restrict gene expression of Vg1 protein. Tight control of Vg1 distribution in this manner is required for proper germ layer specification in the developing embryo. RNA sequence elements in the 3' UTR of the mRNA, the Vg1 localization element (VLE) are required and sufficient to direct transport. To study the recognition and transport of Vg1 mRNA in vivo, we have developed an imaging technique that allows extensive analysis of trans-factor directed transport mechanisms via a simple visual readout. 
To visualize RNA localization, we synthesize fluorescently labeled VLE RNA and microinject this transcript into individual oocytes. After oocyte culture to allow transport of the injected RNA, oocytes are fixed and dehydrated prior to imaging by confocal microscopy. Visualization of mRNA localization patterns provides a readout for monitoring the complete pathway of RNA transport and for identifying roles in directing RNA transport for cis-acting elements within the transcript and trans-acting factors that bind to the VLE (Lewis et al., 2008, Messitt et al., 2008). We have extended this technique through co-localization with additional RNAs and proteins (Gagnon and Mowry, 2009, Messitt et al., 2008), and in combination with disruption of motor proteins and the cytoskeleton (Messitt et al., 2008) to probe mechanisms underlying mRNA localization.

Visualizing RNA Localization in Xenopus Oocytes

Visualization of in vivo RNA transport is accomplished by microinjection of fluorescently labeled RNA transcripts into Xenopus oocytes, followed by confocal microscopy.

Visualizing RNA Localization in Xenopus Oozyten

RNA localization is a conserved mechanism of establishing cell polarity.  Vg1 mRNA localizes to the vegetal pole of Xenopus laevis oocytes and acts to ...

A Fluorescence Microscopy Assay for Monitoring Mitophagy in the Yeast Saccharomyces cerevisiae

Autophagy is important for turnover of cellular components under a range of different conditions. It serves an essential homeostatic function as well as a quality control mechanism that can target and selectively degrade cellular material including organelles1-4. For example, damaged or redundant mitochondria (Fig. 1), not disposed of by autophagy, can represent a threat to cellular homeostasis and cell survival. In the yeast, Saccharomyces cerevisiae, nutrient deprivation (e.g., nitrogen starvation) or damage can promote selective turnover of mitochondria by autophagy in a process termed mitophagy 5-9.
We describe a simple fluorescence microscopy approach to assess autophagy. For clarity we restrict our description here to show how the approach can be used to monitor mitophagy in yeast cells. The assay makes use of a fluorescent reporter, Rosella, which is a dual-emission biosensor comprising a relatively pH-stable red fluorescent protein linked to a pH-sensitive green fluorescent protein. The operation of this reporter relies on differences in pH between the vacuole (pH ~ 5.0-5.5) and mitochondria (pH ~ 8.2) in living cells. Under growing conditions, wild type cells exhibit both red and green fluorescence distributed in a manner characteristic of the mitochondria. Fluorescence emission is not associated with the vacuole. When subjected to nitrogen starvation, a condition which induces mitophagy, in addition to red and green fluorescence labeling the mitochondria, cells exhibit the accumulation of red, but not green fluorescence, in the acidic vacuolar lumen representing the delivery of mitochondria to the vacuole. Scoring cells with red, but not green fluorescent vacuoles can be used as a measure of mitophagic activity in cells5,10-12.

A Fluorescence Microscopy Assay for Monitoring Mitophagy in the Yeast Saccharomyces cerevisiae

A robust approach to monitor the delivery of organelles to the acidic lumen of the yeast vacuole for degradation and recycling is described. The method relies on the specific labeling of target organelles with a genetically encoded dual-emission fluorescence pH-biosensor, and visualization of individual cells using fluorescence microscopy.

Eine Fluoreszenz-Mikroskopie Assay zur Überwachung Mitophagy in der Hefe Saccharomyces cerevisiae

Autophagy is important for turnover of cellular components under a range of different conditions. It serves an essential homeostatic function as well as a ...

Mouse Oocyte Microinjection, Maturation and Ploidy Assessment

Mistakes in chromosome segregation lead to aneuploid cells. In somatic cells, aneuploidy is associated with cancer but in gametes, aneuploidy leads to infertility, miscarriages or developmental disorders like Down syndrome. Haploid gametes form through species-specific developmental programs that are coupled to meiosis. The first meiotic division (MI) is unique to meiosis because sister chromatids remain attached while homologous chromosomes are segregated. For reasons not fully understood, this reductional division is prone to errors and is more commonly the source of aneuploidy than errors in meiosis II (MII) or than errors in male meiosis 1,2. 
In mammals, oocytes arrest at prophase of MI with a large, intact germinal vesicle (GV; nucleus) and only resume meiosis when they receive ovulatory cues. Once meiosis resumes, oocytes complete MI and undergo an asymmetric cell division, arresting again at metaphase of MII. Eggs will not complete MII until they are fertilized by sperm. Oocytes also can undergo meiotic maturation using established in vitro culture conditions 3. Because generation of transgenic and gene-targeted mouse mutants is costly and can take long periods of time, manipulation of female gametes in vitro is a more economical and time-saving strategy. 
Here, we describe methods to isolate prophase-arrested oocytes from mice and for microinjection. Any material of choice may be introduced into the oocyte, but because meiotically-competent oocytes are transcriptionally silent 4,5 cRNA, and not DNA, must be injected for ectopic expression studies. To assess ploidy, we describe our conditions for in vitro maturation of oocytes to MII eggs. Historically, chromosome-spreading techniques are used for counting chromosome number 6. This method is technically challenging and is limited to only identifying hyperploidies. Here, we describe a method to determine hypo-and hyperploidies using intact eggs 7-8. This method uses monastrol, a kinesin-5 inhibitor, that collapses the bipolar spindle into a monopolar spindle 9 thus separating chromosomes such that individual kinetochores can readily be detected and counted by using an anti-CREST autoimmune serum. Because this method is performed in intact eggs, chromosomes are not lost due to operator error.

Oocytes are prone to aneuploidy due to errors in chromosome segregation during meiotic maturation. Aneuploid eggs can cause infertility, miscarriages or developmental disorders like Down syndrome. Here, we describe methods to introduce materials of choice into oocytes and methods to study meiotic maturation and assess ploidy.

Maus Oocyte Mikroinjektion, Reifung und Ploidie Beurteilung

Mistakes in chromosome segregation lead to aneuploid cells.  In somatic cells, aneuploidy is associated with cancer but in gametes, aneuploidy leads to ...

Competitive Genomic Screens of Barcoded Yeast Libraries

By virtue of advances in next generation sequencing technologies, we have access to new genome sequences almost daily. The tempo of these advances is accelerating, promising greater depth and breadth. In light of these extraordinary advances, the need for fast, parallel methods to define gene function becomes ever more important. Collections of genome-wide deletion mutants in yeasts and E. coli have served as workhorses for functional characterization of gene function, but this approach is not scalable, current gene-deletion approaches require each of the thousands of genes that comprise a genome to be deleted and verified. Only after this work is complete can we pursue high-throughput phenotyping. Over the past decade, our laboratory has refined a portfolio of competitive, miniaturized, high-throughput genome-wide assays that can be performed in parallel. This parallelization is possible because of the inclusion of DNA 'tags', or 'barcodes,' into each mutant, with the barcode serving as a proxy for the mutation and one can measure the barcode abundance to assess mutant fitness. In this study, we seek to fill the gap between DNA sequence and barcoded mutant collections. To accomplish this we introduce a combined transposon disruption-barcoding approach that opens up parallel barcode assays to newly sequenced, but poorly characterized microbes. To illustrate this approach we present a new Candida albicans barcoded disruption collection and describe how both microarray-based and next generation sequencing-based platforms can be used to collect 10,000 - 1,000,000 gene-gene and drug-gene interactions in a single experiment.

We have developed comprehensive, unbiased genome-wide screens to understand gene-drug and gene-environment interactions. Methods for screening these mutant collections are presented.

Competitive Genomic Screens von Barcoded Hefe Bibliotheken

By virtue of advances in next generation sequencing technologies, we have access to new genome sequences almost daily.  The tempo of these advances is ...

Chromatographic Purification of Highly Active Yeast Ribosomes

Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers. Particularly troublesome is the fact that lysis of cells releases a large number of proteases and nucleases which can degrade ribosomes. Thus, it is important to separate ribosomes from these enzymes as quickly as possible. Unfortunately, conventional differential ultracentrifugation methods leaves ribosomes exposed to these enzymes for unacceptably long periods of time, impacting their structural integrity and functionality. To address this problem, we utilize a chromatographic method using a cysteine charged Sulfolink resin. This simple and rapid application significantly reduces co-purifying proteolytic and nucleolytic activities, producing high yields of intact, highly biochemically active yeast ribosomes. We suggest that this method should also be applicable to mammalian ribosomes. The simplicity of the method, and the enhanced purity and activity of chromatographically purified ribosome represents a significant technical advancement for the study of eukaryotic ribosomes.

Contamination of preparations of eukaryotic ribosomes purified by traditional methods by co-purifying nucleases and proteases negatively impacts on downstream biochemical and structural analyses. A rapid and simple chromatographic purification method is used to solve this problem using yeast ribosomes as a model system.

Chromatographische Reinigung von hoch aktiven Hefe Ribosomen

Eukaryotic ribosomes are much more labile as compared to their eubacterial and archael counterparts, thus posing a significant challenge to researchers.  ...

The Green Monster Process for the Generation of Yeast Strains Carrying Multiple Gene Deletions

Phenotypes for a gene deletion are often revealed only when the mutation is tested in a particular genetic background or environmental condition1,2. There are examples where many genes need to be deleted to unmask hidden gene functions3,4. Despite the potential for important discoveries, genetic interactions involving three or more genes are largely unexplored. Exhaustive searches of multi-mutant interactions would be impractical due to the sheer number of possible combinations of deletions. However, studies of selected sets of genes, such as sets of paralogs with a greater a priori chance of sharing a common function, would be informative.
In the yeast Saccharomyces cerevisiae, gene knockout is accomplished by replacing a gene with a selectable marker via homologous recombination. Because the number of markers is limited, methods have been developed for removing and reusing the same marker5,6,7,8,9,10. However, sequentially engineering multiple mutations using these methods is time-consuming because the time required scales linearly with the number of deletions to be generated.
Here we describe the Green Monster method for routinely engineering multiple deletions in yeast11. In this method, a green fluorescent protein (GFP) reporter integrated into deletions is used to quantitatively label strains according to the number of deletions contained in each strain (Figure 1). Repeated rounds of assortment of GFP-marked deletions via yeast mating and meiosis coupled with flow-cytometric enrichment of strains carrying more of these deletions lead to the accumulation of deletions in strains (Figure 2). Performing multiple processes in parallel, with each process incorporating one or more deletions per round, reduces the time required for strain construction.
The first step is to prepare haploid single-mutants termed 'ProMonsters,' each of which carries a GFP reporter in a deleted locus and one of the 'toolkit' loci&#x2014;either Green Monster GMToolkit-a or GMToolkit-&alpha; at the can1&Delta; locus (Figure 3). Using strains from the yeast deletion collection12, GFP-marked deletions can be conveniently generated by replacing the common KanMX4 cassette existing in these strains with a universal GFP-URA3 fragment. Each GMToolkit contains: either the a- or &alpha;-mating-type-specific haploid selection marker1 and exactly one of the two markers that, when both GMToolkits are present, collectively allow for selection of diploids.
The second step is to carry out the sexual cycling through which deletion loci can be combined within a single cell by the random assortment and/or meiotic recombination that accompanies each cycle of mating and sporulation.

The Green Monster method enables the rapid assembly of multiple deletions marked with a reporter gene encoding green fluorescent protein. This method is based on driving yeast strains through repeated cycles of sexual assortment of deletions and fluorescence-based enrichment of cells carrying more deletions.

The Green Monster Verfahren zur Erzeugung von Hefestämmen Buchwert Multiple Deletionen

Phenotypes  for a gene deletion are often revealed only when the mutation is tested in a  particular genetic background or environmental condition1,2. ...

The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

The cut-open oocyte Vaseline gap (COVG) voltage clamp technique allows for analysis of electrophysiological and kinetic properties of heterologous ion channels in oocytes. Recordings from the cut-open setup are particularly useful for resolving low magnitude gating currents, rapid ionic current activation, and deactivation. The main benefits over the two-electrode voltage clamp (TEVC) technique include increased clamp speed, improved signal-to-noise ratio, and the ability to modulate the intracellular and extracellular milieu.
Here, we employ the human cardiac sodium channel (hNaV1.5), expressed in Xenopus oocytes, to demonstrate the cut-open setup and protocol as well as modifications that are required to add voltage clamp fluorometry capability.
The properties of fast activating ion channels, such as hNaV1.5, cannot be fully resolved near room temperature using TEVC, in which the entirety of the oocyte membrane is clamped, making voltage control difficult. However, in the cut-open technique, isolation of only a small portion of the cell membrane allows for the rapid clamping required to accurately record fast kinetics while preventing channel run-down associated with patch clamp techniques.
In conjunction with the COVG technique, ion channel kinetics and electrophysiological properties can be further assayed by using voltage clamp fluorometry, where protein motion is tracked via cysteine conjugation of extracellularly applied fluorophores, insertion of genetically encoded fluorescent proteins, or the incorporation of unnatural amino acids into the region of interest1. This additional data yields kinetic information about voltage-dependent conformational rearrangements of the protein via changes in the microenvironment surrounding the fluorescent molecule.

The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

The cut-open Vaseline gap approach is used to obtain low noise recordings of ionic and gating currents from voltage-dependent ion channels expressed in Xenopus oocytes with high resolution of fast channel kinetics. With minor modification, voltage clamp fluorometry can be coupled to the cut-open oocyte protocol.

Die<em&gt; Xenopus</em&gt; Eizelle Cut-open Vaseline Gap Voltage-Clamp-Technik Mit Fluorometrie

The cut-open oocyte Vaseline gap (COVG) voltage clamp technique allows for analysis of electrophysiological and kinetic properties of heterologous ion ...

Surface Spreading and Immunostaining of Yeast Chromosomes

The small size of nuclei of the budding yeast Saccharomyces cerevisiae limits the utility of light microscopy for analysis of the subnuclear distribution of chromatin-bound proteins. Surface spreading of yeast nuclei results in expansion of chromatin without loss of bound proteins. A method for surface spreading balances fixation of DNA bound proteins with detergent treatment. The method demonstrated is slightly modified from that described by Josef Loidl and Franz Klein1,2. The method has been used to characterize the localization of many chromatin-bound proteins at various stages of the mitotic cell cycle, but is especially useful for the study of meiotic chromosome structures such as meiotic recombinosomes and the synaptonemal complex. We also describe a modification that does not require use of Lipsol, a proprietary detergent, which was called for in the original procedure, but no longer commercially available. An immunostaining protocol that is compatible with the chromosome spreading method is also described.

A method for surface-spreading chromosomes from budding yeast is presented. This method is derived from a method previously described by Loidl and Klein. In addition, we demonstrate a procedure for immunostaining of spread chromosomes.

Oberfläche Verbreitung und Immunfärbung von Hefechromosomen

The small size of nuclei of the budding yeast Saccharomyces cerevisiae limits the utility of light microscopy for analysis of the subnuclear distribution ...