Gli autori desiderano ringraziare Glen Slocum (Medical College of Wisconsin) e Colleen A. Lavin (Nikon Instruments Inc) per un&#39;eccellente assistenza tecnica con esperimenti di microscopia. Questo studio è stato sostenuto dal National Institutes of Health concede R01 HL108880 (AS), R01 DK095029 (a OPO) e K99 HL116603 (TSP), National Kidney Foundation IG1724 (TSP), American Heart Association 13GRNT16220002 (a OPO) e Ben J. Lipps Research Fellowship dalla Società Americana di Nefrologia (DVI).

Le procedure sperimentali descritte qui di seguito sono stati approvati dalla cura e l&#39;uso Comitato Animal Istituzionale presso il Medical College del Wisconsin e l&#39;Università del Texas Health Science Center a Houston ed erano in conformità con il National Institutes of Health Guide per la cura e l&#39;uso di animali da laboratorio. Figura 1 illustra le fasi principali di isolamento tessuti e procedura di lavorazione. In breve, reni da PCK o SD ratti sono utilizzati per l&#39;isolamento manuale di monostrati epiteliali di collettori sia da tubuli o cisti non-composto in buona salute. Qui abbiamo studiato reni da 4-16 settimane di età ratti PCK 10,13. 1. Isolamento di renali Cisti e Tubules Collegamento (CNT) / dotti collettori (CD) Segmenti <ol><li> Anestetizzare animale sperimentale con isoflurano (5% di induzione, 1,5-2,5% manutenzione) / medico di grado O 2 o altro metodo riconosciuto. Gli animali devono essere costantemente monitorati per garantire un adeguato level dell&#39;anestesia. Stabile respiratorio reazione votare e punta pizzico vengono utilizzati per confermare l&#39;anestesia corretta. </li><li> Eseguire laparotomia e lavare i reni con tampone fosfato salino (PBS) attraverso l&#39;aorta addominale 17. <ol><li> Preparare un catetere tubo di polietilene (PE50) e collegarlo ad una pompa siringa riempita con PBS. Tagliare la pelle e la parete addominale lungo la linea alba, poi fare una incisione addominale trasversale attraverso l&#39;addome da un lato all&#39;altro e spostare gli organi addominali con tamponi di cotone per ottenere l&#39;accesso alla aorta discendente con ramificazione mesenterica e celiaci arterie. Inumidire gli organi interni con soluzione salina caldo durante ulteriori procedure per impedire la loro secchezza. </li><li> Mettere una legatura (# 1) attorno ai mesenterica e celiaci arterie e un altro legature (# 2) intorno all&#39;aorta sotto il diaframma (non tie). Separare delicatamente a. abdominalis da smussare sezionare tessuti connettivi intorno ad esso con una pinza sottile e mettere due legature ~ 3mm sotto l&#39;arteria renale sinistra (# 3) e al di sopra della biforcazione iliaca (# 4). </li><li> Legare la legatura # 4 e collegare un morsetto nave intorno all&#39;aorta tra l&#39;arteria renale sinistra e legature # 3. Fare un&#39;incisione tra il morsetto e legature # 4 per cateterizzare l&#39;aorta, utilizzare la legatura # 3 per fissare saldamente il catetere. </li><li> Rilasciare il morsetto e fare in modo che l&#39;impulso di sangue è visibile nel catetere per garantire una corretta installazione. Inizia perfusione ad una velocità di 6 ml / min, cravatta legature # 1 e # 2, e tagliare la vena renale sinistra. Continuare a lavare per 1-2 minuti fino a quando gli organi sono completamente scottati. </li><li> Tagliare i vasi sanguigni renali, uretra e circostanti tessuti connettivi adiposi e con le forbici per raccogliere i reni. Poi fare un breve strappo in capsula renale e sbucciare le reni per decapsulate loro. Posizionare i reni in PBS ghiacciato. L&#39;eutanasia è confermata da una toracotomia. </li></ol></li><li> Preparare 5 x 5 mm chip vetro coperchio rivestito con poli-L-lisina. Tagliare una gla copertinass con una matita diamante e posto circa 20 ml di 0,01% sterile soluzione filtrata Poly-L-lisina su ogni chip vetro. Preparare salina e due paia di pinze orologeria per la dissezione. </li><li> Tagliare i reni con una lametta lungo il piano frontale in fette di ~ 1-2 mm di spessore. Mettere una delle fette sotto uno stereomicroscopio. Isolamento di tessuti dovrebbe essere fatto in soluzione salina ghiacciata. </li><li> Individuare cisti allo stereomicroscopio come cavità rotondo-figura (Figura 2A); le loro pareti contengono spesso rete importante di vasi sanguigni proliferato. Uso pinze punta fine sezionano lo strato epiteliale interna di una cisti più sottile possibile per ottenere una zona monostrato. Attaccare ad un chip di vetro rivestito con poli-L-lisina. Appiccicoso superficie Poly-L-lisina permette al ricercatore di posizionare saldamente lo strato cisti interna su vetro. Esporre la cisti con il lato apicale per fornire l&#39;accesso alle pipette (Figura 2B). </li><li> Utilizzare PCK o ratto SD bambinofette centrali ney contenenti papilla per l&#39;isolamento di non dilatate CNT / CCDsegments 18-21. NOTA: i tessuti papillari sono più durevoli di corteccia e tenendo fasce tubolari papillari con una pinza e strappando lungo l&#39;asse radiale fetta può essere scisso in settori sottili. Tubuli individuali sono visibili e possono essere estratte per essere immessi sul chip di vetro di copertura. </li><li> Identificare i segmenti CNT / CCD da biforcazioni, una maggiore trasparenza di tubuli prossimali e grandi cellule prominente visibili (Figura 2C). Posizionare il chip vetro di copertura con tubuli collegati al microscopio equipaggiato con micromanipolatori adatti per micropipette guida. Utilizzando micropipette taglienti tubuli split-aperti e fissare i bordi al vetro per rendere la superficie apicale accessibili (Figura 2D). </li></ol> Elettrofisiologia 2. Single Channel Patch-clamp <ol><li> Riempire la camera del patch-clamp con soluzione del bagno e trasferire il chip vetro di coperturacon tessuti isolati alla camera. Assicurarsi che le micropipette patch-clamp hanno una resistenza di 7-10 MW per misurazioni affidabili (cella-attached) su celle. </li><li> Per le misure di cella-attached, impostare il rapporto di guadagno dell&#39;amplificatore a 20x e passa-basso le correnti a 300 Hz, da un filtro a otto poli Bessel. Per il monitoraggio canali ENaC, utilizzare una soluzione del bagno, in mm: 150 NaCl, 1 CaCl 2, 2 MgCl 2, 10 HEPES (pH 7,4); pipetta: 140 LiCl, 2 MgCl 2 e 10 HEPES (pH 7,4). </li><li> Condurre un esperimento di patch-clamp convenzionale in una modalità cella-attached 10. Selezionare una cella nel monostrato epiteliale e avvicinare la pipetta alla membrana apicale. Formare una guarnizione ad alta resistenza tra la pipetta e la membrana cellulare applicando aspirazione delicata. Una volta che un ad alta resistenza di tenuta gigaohm è formato, un protocollo senza gap ad un potenziale in possesso deve essere avviato un&#39;attività di monitoraggio del canale di interesse. </li><li> Dati del canale unico negozio gap-liberi corrente da gigaGuarnizioni Ohm per successive analisi. Analizzare gli eventi canale utilizzando un pacchetto software generalmente fornito con configurazioni di patch-clamp 18. Calcolare canale attività come NpO dove N indica il numero di canali attivi nella patch e P o è probabilità media aperta dei canali. NOTA: Utilizzare le cisti isolate o tubuli in esperimenti di patch-clamp per non più di 30 min. </li></ol> 3. Raziometrico epifluorescenza misurazioni della concentrazione intracellulare di calcio nelle cellule epiteliali <ol><li> Utilizzare 5 mM Fura-02:00 sciolto in DMSO. Soluzione Aliquota magazzino in tubi conici singoli 500 microlitri (circa 10 ml). Proteggere dalla luce e conservare in freezer a -20 ° C per un massimo di sei mesi. </li><li> Incubare le cisti isolate e tubuli spaccatura-aperto per 30-40 minuti a PSS (in mm: 145 NaCl, KCl 4.5, 2 MgCl 2, 2 CaCl 2 e 10 HEPES a pH 7,35) contenenti 5 mM Fura-02:00 colorante e 0.05% di acido Pluronic per aiutare disperdere le esteri acetossimetil. Per questo, posto tessuti del piatto 3.5 cm contenente loading cocktail, proteggere dalla luce e incubare su un agitatore lento a temperatura ambiente. </li><li> Cambia Fura-02:00 contenenti supporti per pulire PSS dopo l&#39;incubazione e posizionare il tessuto al microscopio per eseguire ulteriori immagini epifluorescenza. </li><li> Accendere camera CCD e luce stabile (sistema monocromatore) dotata di ruota portafiltri (ogni posizione del filtro può essere associato ad un proprio livello di attenuazione, selezionato ogni volta che il filtro è chiamato). </li><li> Trova il tessuto in campo chiaro. Passare il rilevamento del segnale di fluorescenza e regolare l&#39;intensità della sorgente di luce utilizzando filtri a densità neutra e potenza della lampada per evitare la saturazione del segnale. </li><li> Monitor Fura-2 AM fluorescenza nel campione di tessuto con eccitazione a 340/380 nm raziometrico con una frequenza di 0,125 Hz o superiore. Utilizzare un 40 × / NA 1.3 o simile lenti dell&#39;obiettivo per una corretta risoluimmagine zione. </li><li> Per l&#39;elaborazione delle immagini e calcoli importare la sequenza di immagini. Assicurati di dividere i canali e utilizzare una modalità HyperStack scala di grigi. Seleziona più regioni di interesse (cellule singolo cisti o aree selezionate di tessuto cistica) e calcolare i valori di intensità per ciascun canale (340 e 380 nm) in preferito software di analisi dei dati; sottrazione di valori di intensità di fondo da ogni punto di dati. </li><li> Per ogni punto di tempo calcolare il rapporto tra intensità delle 340 a 380 canali Fura-2 AM. Grafico a dispersione / linea point-tempo cambia di Ca 2+ transitoria per ogni regione e calcolare i valori medi / SE. </li></ol>

The authors have nothing to disclose.

Abbiamo descritto qui applicazioni della tradizionale tecnica del patch-clamp e di imaging epifluorescenza calcio per monostrati epiteliali cistica derivate da un modello genetico murino di ARPKD. Il protocollo consiste di tre fasi, di cui la più attenzione deve essere rivolta alla l&#39;isolamento delle cisti (passo 1.5 della sezione di protocolli) e per gli studi elettrofisiologici. Queste procedure chiave richiedono una formazione completa e la pazienza, e il lettore non deve essere frustrato in una volta. <p cl...

Canali ionici svolgono un ruolo significativo in molte funzioni fisiologiche, tra cui la crescita cellulare e la differenziazione. Malattie autosomiche dominanti e recessivi policistiche renali (ADPKD e ARPKD, rispettivamente) sono malattie genetiche caratterizzate dallo sviluppo di cisti renali piene di liquido di origine tubulare delle cellule epiteliali. ADPKD è causata da mutazioni di PKD1 o PKD2 geni che codificano policistine 1 e 2, proteine ​​di membrana coinvolte nella regolazione della proliferazione e differenziazione cellulare. PKD2 da solo o come un complesso con PKD1 funzionare anche come Ca 2+ canale cationico -permeable 1. Le mutazioni del gene che codifica PKHD1 fibrocistina (una proteina recettore simil-cilia associata coinvolte nella tubulogenesi e / o manutenzione di polarità di epitelio) sono l&#39;impulso genetico di ARPKD 2. Crescita delle cisti è un fenomeno complesso accompagnato da proliferazione disturbato 3,4, angiogenesi 5, dedifferenziazione e la perdita di polarilità di cellule tubulari 6-8. Riassorbimento difettoso e la secrezione aumentata in cistico contribuiscono all&#39;accumulo di liquidi nel lume e cisti espansione 9,10. Flusso-dipendente alterata [Ca 2+] i segnalazione è stata anche legata alla cystogenesis durante PKD 11-15. Qui, si descrive un metodo adatto per misure patch-clamp di attività singolo canale e intracellulari di Ca 2+ livelli in monostrati epiteliali cistiche isolati da ratti PCK. Questo metodo è stato applicato con successo da noi per caratterizzare l&#39;attività del canale epiteliale Na + (ENaC) e 10 [Ca 2+] i indotti da processi -dipendente Ca 2+ TRPV4 -permeable e purinergica cascata di segnalazione 13. In questi studi abbiamo utilizzato topi PCK, un modello di ARPKD causata da una mutazione spontanea nel gene PKHD1. Il ceppo PCK era originally derivate da ratti 16 ratti così SD sono utilizzati come controllo appropriato per il confronto con il ceppo Sprague-Dawley PCK (SD). Di conseguenza, entrambi i ratti nefrone SD e condotti non dilatato raccolta isolati da ratti stesso PCK possono servire come due diversi gruppi di confronto per esperimenti su cistico.

<table border="0" cellpadding="0" cellspacing="0" width="1015">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Fura-2 AM</td>
			<td style="width:219px;">Life Technologies</td>
			<td style="width:183px;">F-14185</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Flou-8</td>
			<td style="width:219px;">AAT Bioquest</td>
			<td style="width:183px;">21091</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Poly-L-lysine</td>
			<td style="width:219px;">Sigma-Aldrich</td>
			<td style="width:183px;">P4707</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Pluronic acid</td>
			<td style="width:219px;">Sigma-Aldrich</td>
			<td style="width:183px;">F-68&#160;</td>
			<td style="width:333px;">solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Shaker</td>
			<td style="width:219px;">Boekel Scientific</td>
			<td style="width:183px;">260350</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Light source</td>
			<td style="width:219px;">Sutter Instrument Co</td>
			<td style="width:183px;">Lambda XL</td>
			<td style="width:333px;">with integrated shutter/filter wheel driver</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Neutral density filters</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;"></td>
			<td style="width:333px;">ND4, ND8</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Objective</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;">SFluo&#160;</td>
			<td style="width:333px;">40/1.3 DIC WD 0.22&#160;&#160; oil</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Camera</td>
			<td style="width:219px;">Andor Technologies</td>
			<td style="width:183px;">Zyla sCMOS</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:283px;">Nikon&#160; microscope (inverted)</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;">Nikon Eclipse TE2000-S</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Cover Glass</td>
			<td style="width:219px;">Thermo Scientific</td>
			<td style="width:183px;">6661B52</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Diamond pencil</td>
			<td style="width:219px;">Fisher Scientific</td>
			<td style="width:183px;">22268912</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Image acquisition software</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;">Nikon NIS-Elements&#160;</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:283px;">Image analysis software</td>
			<td style="width:219px;">ImageJ</td>
			<td style="width:183px;">http://imagej.nih.gov/</td>
			<td style="width:333px;">ND Utility plugin allows to import images in the native Nikon Instruments .nd2 format</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Recording/perfusion chamber</td>
			<td style="width:219px;">Warner Instruments</td>
			<td style="width:183px;">RC-26</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;"></td>
			<td style="width:219px;"></td>
			<td style="width:183px;"></td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Patch Clamp amplifier</td>
			<td style="width:219px;">Molecular Devices</td>
			<td style="width:183px;">MultiClamp 700B</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Data Acquisition System</td>
			<td style="width:219px;">Molecular Devices</td>
			<td style="width:183px;">Digidata 1440A</td>
			<td style="width:333px;">Axon Digidata&#174; System</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Low Pass Filter</td>
			<td style="width:219px;">Warner Instruments</td>
			<td style="width:183px;">LPF-8</td>
			<td style="width:333px;">8 pole Bessel</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Borosilicate glass capillaries</td>
			<td style="width:219px;">World Precision Instruments</td>
			<td style="width:183px;">1B150F-4</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="29">
			<td height="29" style="height:29px;width:283px;">Micropipette Puller</td>
			<td style="width:219px;">Sutter Instrument Co</td>
			<td style="width:183px;">P-97</td>
			<td style="width:333px;">Flaming/Brown type micropipette puller</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Microforge</td>
			<td style="width:219px;">Narishige</td>
			<td style="width:183px;">MF-830</td>
			<td style="width:333px;">Japan</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Motorized Micromanipulator</td>
			<td style="width:219px;">Sutter Instrument Co</td>
			<td style="width:183px;">MP-225</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Inverted microscope</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;">Eclipse Ti</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Microvibration isolation table</td>
			<td style="width:219px;">TMC</td>
			<td style="width:183px;"></td>
			<td style="width:333px;">equipped with Faraday cage</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Multichannel valve perfusion system</td>
			<td style="width:219px;">AutoMake Scientific</td>
			<td style="width:183px;">Valve Bank II</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Recording/perfusion chamber</td>
			<td style="width:219px;">Warner Instruments</td>
			<td style="width:183px;">RC-26</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Software</td>
			<td style="width:219px;">Molecular Devices</td>
			<td style="width:183px;">pClamp 10 . 2</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;"></td>
			<td style="width:219px;"></td>
			<td style="width:183px;"></td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Temperature controlled surgical table&#160;</td>
			<td style="width:219px;">MCW core</td>
			<td style="width:183px;"></td>
			<td style="width:333px;">for rodents</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Binocular stereomicroscope</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;">SMZ745</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Syringe pump-based perfusion system</td>
			<td style="width:219px;">Harvard Apparatus</td>
			<td style="width:183px;"></td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">polyethylene tubing</td>
			<td style="width:219px;">Sigma-Aldrich</td>
			<td style="width:183px;">PE50</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Isofluorane anesthesia</td>
			<td style="width:219px;"><a href="http://www.vetequip.com/">http://www.vetequip.com/</a></td>
			<td style="width:183px;">911103</td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;"></td>
			<td style="width:219px;"></td>
			<td style="width:183px;"></td>
			<td style="width:333px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Other basic reagents</td>
			<td style="width:219px;">Sigma-Aldrich</td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

implementing patch clamp and live fluorescence microscopy to monitor functional properties of freshly isolated pkd epithelium

Cisti di iniziazione e di espansione durante la malattia del rene policistico è un processo complesso, caratterizzata da anomalie nella proliferazione delle cellule tubulari, accumulo di liquidi luminale e la formazione della matrice extracellulare. Attività di canali ionici e di segnalazione intracellulare di calcio sono parametri fisiologici fondamentali che determinano le funzioni di epitelio tubolare. Abbiamo sviluppato un metodo adatto per l&#39;osservazione in tempo reale dell&#39;attività canali ionici con la tecnica patch-clamp e registrazione di Ca2 + intracellulare in monostrati epiteliali livello appena isolate da cisti renali. Ratti PCK, un modello genetico di autosomica recessiva rene policistico (ARPKD), sono stati utilizzati qui per ex vivo l&#39;analisi dei canali ionici e del flusso di calcio. Descritto qui è una procedura dettagliata passo-passo progettato per isolare monostrati cistica e tubuli non dilatata da PCK o normali Sprague Dawley (SD) ratti, e monitorare l&#39;attività a canale singolo e intracellulari di Ca 2+ dinamiche.Questo metodo non richiede trattamento enzimatico e consente l&#39;analisi in un ambiente nativo di fresco isolato monostrato epiteliale. Inoltre, questa tecnica è molto sensibile alle variazioni intracellulari di calcio e genera immagini ad alta risoluzione per misurazioni precise. Infine, isolato cistico può essere ulteriormente utilizzato per la colorazione con anticorpi o coloranti, preparazione di colture primarie e di purificazione per i vari saggi biochimici.

Coinvolgimento potenziale ENaC in cystogenesis è stata dimostrata da diversi studi che osservano interrotto fattore di crescita epidermico (EGF) di segnalazione in PKD progressione 22-25 e riassorbimento di sodio anormale ARPKD modelli murini e colture di tessuti 26-28. Ad esempio, Veizis et al. Hanno dimostrato che amiloride-sensibile Na + assorbimento è diminuita nelle cellule CD dal non orthologous modello murino di BPK ARPKD 29. Abbiamo recentemente dimostrato c...

Watch this Scientific Journal Video about Implementing Patch Clamp and Live Fluorescence Microscopy to Monitor Functional Properties of Freshly Isolated PKD Epithelium at JoVE.com

Implementing Patch Clamp and Live Fluorescence Microscopy to Monitor Functional Properties of Freshly Isolated PKD Epithelium

Canali ionici espressi in renale tubulare svolgono un ruolo significativo nella patologia della malattia del rene policistico. Qui si descrive protocolli sperimentali utilizzati per eseguire patch-clamp analisi e di livello di calcio intracellulare misure in cistico appena isolato da reni di roditori.

Implementazione Patch Clamp e vivo microscopia a fluorescenza per il monitoraggio delle proprietà funzionali di recente isolato PKD Epithelium

Cyst initiation and expansion during polycystic kidney disease is a complex process characterized by abnormalities in tubular cell proliferation, luminal ...

implementing-patch-clamp-live-fluorescence-microscopy-to-monitor

Research

JoVE Journal

Biology

9.7K Views.  Medical College of Wisconsin.  Canali ionici espressi in renale tubulare svolgono un ruolo significativo nella patologia della malattia del rene policistico. Qui si descrive protocolli sperimentali utilizzati per eseguire patch-clamp analisi e di livello di calcio intracellulare misure in cistico appena isolato da reni di roditori. 

Video: Implementing Patch Clamp and Live Fluorescence Microscopy to Monitor Functional Properties of Freshly Isolated PKD Epithelium

Methods for Patch Clamp Capacitance Recordings from the Calyx

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal. Electrical recordings from the presynaptic terminal allow the measurement of action potentials, calcium channel currents, vesicle fusion (exocytosis) and subsequent membrane uptake (endocytosis). The fusion of vesicles containing neurotransmitter causes the vesicle membrane to be added to the cell membrane of the calyx. This increase in the amount of cell membrane is measured as an increase in capacitance. The subsequent reduction in capacitance indicates endocytosis, the process of membrane uptake or removal from the calyx membrane. Endocytosis, is necessary to maintain the structure of the calyx and it is also necessary to form vesicles that will be filled with neurotransmitter for future exocytosis events. Capacitance recordings at the calyx of Held have made it possible to directly and rapidly measure vesicular release and subsequent endocytosis in a mammalian CNS nerve terminal. In addition, the corresponding postsynaptic activity can be simultaneously measured by using paired recordings. Thus a complete picture of the presynaptic and postsynaptic electrical activity at a central nervous system synapse is achievable using this preparation. Here, the methods for slice preparation, morphological features for identification of calyces of Held, basic patch clamping techniques, and examples of capacitance recordings to measure exocytosis and endocytosis are presented.

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal.

Metodi per la registrazioni Morsetto capacità patch dal Calyx

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal. ...

Ricerca

Biologia

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 di registrazione pinza dei canali ionici Espressa in ovociti di Xenopus

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

Pressure-polishing Pipettes for Improved Patch-clamp Recording

Pressure-polishing is a method for shaping glass pipettes for patch-clamp recording. We first developed this method for fabricating pipettes suitable for recording from small (&lt;3 m) neuronal cell bodies. The basic principal is similar to glass-blowing and combines air pressure and heat to modify the shape of patch pipettes prepared by a conventional micropipette puller. It can be applied to so-called soft (soda lime) and hard (borosilicate) glasses. Generally speaking, pressure polishing can reduce pipette resistance by 25% without decreasing the diameter of the tip opening (Goodman and Lockery, 2000). It can be applied to virtually any type of glass and requires only the addition of a high-pressure valve and fitting to a microforge. This technique is essential for recording from ultrasmall cells (&lt;5 m) and can also improve single-channel recording by minimizing pipette resistance. The blunt shape is also useful for perforated-patch clamp recording since this tip shape results in a larger membrane bleb available for perforation.

This is a guide to modifying the shape of glass micropipettes. Specifically, by using heat and air pressure the taper is widened without increasing the tip opening, leading to lower pipette resistance. This is critical to obtain low noise recordings of small cells but is useful in many applications.

Pressione lucidatura Pipette per una migliore patch-clamp di registrazione

Pressure-polishing is a method for shaping glass pipettes for patch-clamp recording.  We first developed this method for fabricating pipettes suitable for ...

Time-lapse Imaging of Mitosis After siRNA Transfection

Changes in cellular organization and chromosome dynamics that occur during mitosis are tightly coordinated to ensure accurate inheritance of genomic and cellular content. Hallmark events of mitosis, such as chromosome movement, can be readily tracked on an individual cell basis using time-lapse fluorescence microscopy of mammalian cell lines expressing specific GFP-tagged proteins. In combination with RNAi-based depletion, this can be a powerful method for pinpointing the stage(s) of mitosis where defects occur after levels of a particular protein have been lowered. In this protocol, we present a basic method for assessing the effect of depleting a potential mitotic regulatory protein on the timing of mitosis. Cells are transfected with siRNA, placed in a stage-top incubation chamber, and imaged using an automated fluorescence microscope. We describe how to use software to set up a time-lapse experiment, how to process the image sequences to make either still-image montages or movies, and how to quantify and analyze the timing of mitotic stages using a cell-line expressing mCherry-tagged histone H2B. Finally, we discuss important considerations for designing a time-lapse experiment. This strategy is complementary to other approaches and offers the advantages of 1) sensitivity to changes in kinetics that might not be observed when looking at cells as a population and 2) analysis of mitosis without the need to synchronize the cell cycle using drug treatments. The visual information from such imaging experiments not only allows the sub-stages of mitosis to be assessed, but can also provide unexpected insight that would not be apparent from cell cycle analysis by FACS.

Here we describe a basic protocol to image and quantify the mitotic timing of live mammalian tissue culture cells after siRNA transfection.

Time-lapse imaging di mitosi dopo la trasfezione di siRNA

Changes in cellular organization and chromosome dynamics that occur during mitosis are tightly coordinated to ensure accurate inheritance of genomic and ...

Fluorescence-based Measurement of Store-operated Calcium Entry in Live Cells: from Cultured Cancer Cell to Skeletal Muscle Fiber

Store operated Ca2+ entry (SOCE), earlier termed capacitative Ca2+ entry, is a tightly regulated mechanism for influx of extracellular Ca2+ into cells to replenish depleted endoplasmic reticulum (ER) or sarcoplasmic reticulum (SR) Ca2+ stores1,2. Since Ca2+ is a ubiquitous second messenger, it is not surprising to see that SOCE plays important roles in a variety of cellular processes, including proliferation, apoptosis, gene transcription and motility. Due to its wide occurrence in nearly all cell types, including epithelial cells and skeletal muscles, this pathway has received great interest3,4. However, the heterogeneity of SOCE characteristics in different cell types and the physiological function are still not clear5-7.
The functional channel properties of SOCE can be revealed by patch-clamp studies, whereas a large body of knowledge about this pathway has been gained by fluorescence-based intracellular Ca2+ measurements because of its convenience and feasibility for high-throughput screening. The objective of this report is to summarize a few fluorescence-based methods to measure the activation of SOCE in monolayer cells, suspended cells and muscle fibers5,8-10. The most commonly used of these fluorescence methods is to directly monitor the dynamics of intracellular Ca2+ using the ratio of F340nm and F380nm (510 nm for emission wavelength) of the ratiometric Ca2+ indicator Fura-2. To isolate the activity of unidirectional SOCE from intracellular Ca2+ release and Ca2+ extrusion, a Mn2+ quenching assay is frequently used. Mn2+ is known to be able to permeate into cells via SOCE while it is impervious to the surface membrane extrusion processes or to ER uptake by Ca2+ pumps due to its very high affinity with Fura-2. As a result, the quenching of Fura-2 fluorescence induced by the entry of extracellular Mn2+ into the cells represents a measurement of activity of SOCE9. Ratiometric measurement and the Mn+2 quenching assays can be performed on a cuvette-based spectrofluorometer in a cell population mode or in a microscope-based system to visualize single cells. The advantage of single cell measurements is that individual cells subjected to gene manipulations can be selected using GFP or RFP reporters, allowing studies in genetically modified or mutated cells. The spatiotemporal characteristics of SOCE in structurally specialized skeletal muscle can be achieved in skinned muscle fibers by simultaneously monitoring the fluorescence of two low affinity Ca2+ indicators targeted to specific compartments of the muscle fiber, such as Fluo-5N in the SR and Rhod-5N in the transverse tubules9,11,12.

The extent of store-operated Ca2+ entry (SOCE) can be monitored using fluorescent Ca2+ indicators. Mn2+ quenching of such indicators assays SOCE in cultured cells and skeletal muscle fibers. A technique allowing spatial and temporal resolution of SOCE by confocal imaging of mechanically skinned muscle fibers is also described.

Basato sulla fluorescenza Misura Store-Entry operato di calcio in cellule vive: dal Cancer Cell coltura per fibra muscolare scheletrica

Store operated Ca2+ entry (SOCE), earlier termed capacitative Ca2+ entry, is a tightly regulated mechanism for influx of extracellular Ca2+ into cells to ...

Quantitative Live Cell Fluorescence-microscopy Analysis of Fission Yeast

Several microscopy techniques are available today that can detect a specific protein within the cell. During the last decade live cell imaging using fluorochromes like Green Fluorescent Protein (GFP) directly attached to the protein of interest has become increasingly popular 1. Using GFP and similar fluorochromes the subcellular localisations and movements of proteins can be detected in a fluorescent microscope. Moreover, also the subnuclear localisation of a certain region of a chromosome can be studied using this technique. GFP is fused to the Lac Repressor protein (LacR) and ectopically expressed in the cell where tandem repeats of the lacO sequence has been inserted into the region of interest on the chromosome2. The LacR-GFP will bind to the lacO repeats and that area of the genome will be visible as a green dot in the fluorescence microscope. Yeast is especially suited for this type of manipulation since homologous recombination is very efficient and thereby enables targeted integration of the lacO repeats and engineered fusion proteins with GFP 3. Here we describe a quantitative method for live cell analysis of fission yeast. Additional protocols for live cell analysis of fission yeast can be found, for example on how to make a movie of the meiotic chromosomal behaviour 4. In this particular experiment we focus on subnuclear organisation and how it is affected during gene induction. We have labelled a gene cluster, named Chr1, by the introduction of lacO binding sites in the vicinity of the genes. The gene cluster is enriched for genes that are induced early during nitrogen starvation of fission yeast 5. In the strain the nuclear membrane (NM) is labelled by the attachment of mCherry to the NM protein Cut11 giving rise to a red fluorescent signal. The Spindle Pole body (SPB) compound Sid4 is fused to Red Fluorescent Protein (Sid4-mRFP) 6. In vegetatively growing yeast cells the centromeres are always attached to the SPB that is embedded in the NM 7. The SPB is identified as a large round structure in the NM. By imaging before and 20 minutes after depletion of the nitrogen source we can determine the distance between the gene cluster (GFP) and the NM/SPB. The mean or median distances before and after nitrogen depletion are compared and we can thus quantify whether or not there is a shift in subcellular localisation of the gene cluster after nitrogen depletion.

The fission yeast, Schizosaccharomyces pombe, is a good model system to study basic cellular processes. Here we describe a method to perform quantitative live cell analysis of fission yeast. In this particular experiment we focus on organisation of the genome within the cell nucleus, but the method can also be used to study cytosolic factors.

Quantitativa vivo cellulare-microscopio a fluorescenza Analisi di lievito Fission

Several microscopy techniques are available today that can detect a specific protein within the cell. During the last decade live cell imaging using ...

Giant Liposome Preparation for Imaging and Patch-Clamp Electrophysiology

The reconstitution of ion channels into chemically defined lipid membranes for electrophysiological recording has been a powerful technique to identify and explore the function of these important proteins. However, classical preparations, such as planar bilayers, limit the manipulations and experiments that can be performed on the reconstituted channel and its membrane environment. The more cell-like structure of giant liposomes permits traditional patch-clamp experiments without sacrificing control of the lipid environment.
Electroformation is an efficient mean to produce giant liposomes &gt;10 &mu;m in diameter which relies on the application of alternating voltage to a thin, ordered lipid film deposited on an electrode surface. However, since the classical protocol calls for the lipids to be deposited from organic solvents, it is not compatible with less robust membrane proteins like ion channels and must be modified. Recently, protocols have been developed to electroform giant liposomes from partially dehydrated small liposomes, which we have adapted to protein-containing liposomes in our laboratory.
We present here the background, equipment, techniques, and pitfalls of electroformation of giant liposomes from small liposome dispersions. We begin with the classic protocol, which should be mastered first before attempting the more challenging protocols that follow. We demonstrate the process of controlled partial dehydration of small liposomes using vapor equilibrium with saturated salt solutions. Finally, we demonstrate the process of electroformation itself. We will describe simple, inexpensive equipment that can be made in-house to produce high-quality liposomes, and describe visual inspection of the preparation at each stage to ensure the best results.

Reconstituting functional membrane proteins into giant liposomes of defined composition is a powerful approach when combined with patch-clamp electrophysiology. However, conventional giant liposome production may be incompatible with protein stability. We describe protocols for producing giant liposomes from pure lipids or small liposomes containing ion channels.

Giant Preparazione liposomi per Immagini e di patch-clamp elettrofisiologia

The reconstitution of ion channels into chemically defined lipid membranes for electrophysiological recording has been a powerful technique to identify ...

One-channel Cell-attached Patch-clamp Recording

Ion channel proteins are universal devices for fast communication across biological membranes. The temporal signature of the ionic flux they generate depends on properties intrinsic to each channel protein as well as the mechanism by which it is generated and controlled and represents an important area of current research. Information about the operational dynamics of ion channel proteins can be obtained by observing long stretches of current produced by a single molecule. Described here is a protocol for obtaining one-channel cell-attached patch-clamp current recordings for a ligand gated ion channel, the NMDA receptor, expressed heterologously in HEK293 cells or natively in cortical neurons. Also provided are instructions on how to adapt the method to other ion channels of interest by presenting the example of the mechano-sensitive channel PIEZO1. This method can provide data regarding the channel&#8217;s conductance properties and the temporal sequence of open-closed conformations that make up the channel&#8217;s activation mechanism, thus helping to understand their functions in health and disease.

Described here is a procedure for obtaining long stretches of current recording from one ion channel with the cell-attached patch-clamp technique. This method allows for observing, in real time, the pattern of open-close channel conformations that underlie the biological signal. These data inform about channel properties in undisturbed biological membranes.

Un canale Cell-allegato patch-clamp registrazione

Ion channel proteins are universal devices for fast communication across biological membranes. The temporal signature of the ionic flux they generate ...

Reconstitution of a Transmembrane Protein, the Voltage-gated Ion Channel, KvAP, into Giant Unilamellar Vesicles for Microscopy and Patch Clamp Studies

Giant Unilamellar Vesicles (GUVs) are a popular biomimetic system for studying membrane associated phenomena. However, commonly used protocols to grow GUVs must be modified in order to form GUVs containing functional transmembrane proteins. This article describes two dehydration-rehydration methods &#8212; electroformation and gel-assisted swelling &#8212; to form GUVs containing the voltage-gated potassium channel, KvAP. In both methods, a solution of protein-containing small unilamellar vesicles is partially dehydrated to form a stack of membranes, which is then allowed to swell in a rehydration buffer. For the electroformation method, the film is deposited on platinum electrodes so that an AC field can be applied during film rehydration. In contrast, the gel-assisted swelling method uses an agarose gel substrate to enhance film rehydration. Both methods can produce GUVs in low (e.g., 5 mM) and physiological (e.g., 100 mM) salt concentrations. The resulting GUVs are characterized via fluorescence microscopy, and the function of reconstituted channels measured using the inside-out patch-clamp configuration. While swelling in the presence of an alternating electric field (electroformation) gives a high yield of defect-free GUVs, the gel-assisted swelling method produces a more homogeneous protein distribution and requires no special equipment.

The reconstitution of the transmembrane protein, KvAP, into giant unilamellar vesicles (GUVs) is demonstrated for two dehydration-rehydration methods &#8212; electroformation, and gel-assisted swelling. In both methods, small unilamellar vesicles containing the protein are fused together to form GUVs that can then be studied by fluorescence microscopy and patch-clamp electrophysiology.

Ricostituzione di una proteina transmembrana, la tensione gated canali ionici, KvAP, in Giant unilamellari vescicole per la microscopia e Patch Clamp Studies

Giant Unilamellar Vesicles (GUVs) are a popular biomimetic system for studying membrane associated phenomena. However, commonly used protocols to grow ...

Single-channel Analysis and Calcium Imaging in the Podocytes of the Freshly Isolated Glomeruli

Podocytes (renal glomerular epithelial cells) are known to regulate glomerular permeability and maintain glomerular structure; a key role for these cells in the pathogenesis of various renal diseases has been established since podocyte injury leads to proteinuria and foot process effacement. It was previously reported that various endogenous agents may cause a dramatic overload in intracellular Ca2+ concentration in podocytes, presumably leading to albuminuria, and this likely occurs via calcium-conducting ion channels. Therefore, it appeared important to study calcium handling in the podocytes both under normal conditions and in various pathological states. However, available experimental approaches have remained somewhat limited to cultured and transfected cells. Although they represent a good basic model for such studies, they are essentially extracted from the native environment of the glomerulus. Here we describe the methodology of studying podocytes as a part of the freshly isolated whole glomerulus. This preparation retains the functional potential of the podocytes, which are still attached to the capillaries; therefore, podocytes remain in the environment that conserves the major parts of the glomeruli filtration apparatus. The present manuscript elaborates on two experimental approaches that allow 1) real-time detection of calcium concentration changes with the help of ratiometric confocal fluorescence microscopy, and 2) the recording of the single ion channels activity in the podocytes of the freshly isolated glomeruli. These methodologies utilize the advantages of the native environment of the glomerulus that enable researchers to resolve acute changes in the intracellular calcium handling in response to applications of various agents, measure basal concentration of calcium within the cells (for instance, to evaluate disease progression), and assess and manipulate calcium conductance at the level of single ion channels.

Changes in the intracellular calcium levels in the podocytes are one of the most important means to control the filtration function of glomeruli. Here we explain a high-throughput approach that allows detection of real-time calcium handling and single ion channels activity in the podocytes of the freshly isolated glomeruli.

Monocanale Analisi e Imaging di calcio nei podociti del Freshly Isolato glomeruli

Podocytes (renal glomerular epithelial cells) are known to regulate glomerular permeability and maintain glomerular structure; a key role for these cells ...