Questo lavoro è stato sostenuto dal National Institutes of Health (DP1CA174426 di Carlos F. Barbas) e ShanghaiTech University di Shanghai, in Cina (a JL). Grafici molecolari sono stati generati utilizzando PyMol.

1. Clonazione <ol><li> Ottenere domini Zif due dita alanina-sostituiti che sono stati sub-clonati nel sistema vettore di espressione pET-28 e sono disponibili su richiesta (PET-2F-ZIF). 34 </li><li> PCR amplifica EmGFP dal plasmide Emerald-pBAD con primer 5 &#39;XmaI-EmGFP (5&#39;-GGAAATTG CCCGGG ATGGTGAGCAAGGGCGAGGAGCTGTTCAC-3&#39;; Xma sito ho in grassetto) e 3 &#39;SacI-EmGFP (5&#39;-CGGATCT GAGCTC TTACTTGTACAGCTCGTCCATGCCGAG-3&#39; ; Sac sito che ho in grassetto). <ol><li> Utilizzare 5 ng di DNA stampo, 10 microlitri di tampone 10x polimerasi, 1 unità (U) di DNA polimerasi Taq, 0,2 mM ciascun dNTP e 0,2 mM di ciascun primer in una soluzione di 100 microlitri con il volume rimanente costituiti di acqua distillata / deionizzata . Utilizzare le condizioni di ciclismo: 95 ° C per 5 minuti; 30 cicli di 95 ° C per 30 sec, 55 ° C per 30 sec e 72 ° C per 1 min; 72 ° C per 10 min. Purificare il prodotto PCR gel extraction e determinare la concentrazione di DNA utilizzando uno spettrofotometro misura Abs 260 x 50 ug / ml. </li></ol></li><li> Digest pET-2F-ZIF e l&#39;inserto codifica EmGFP con gli enzimi di restrizione Xma I e Sac I in tampone raccomandato per 3 ore a 37 ° C utilizzando 10 U di enzima per 1 mg di DNA. Visualizza DNA mediante elettroforesi su gel di agarosio utilizzando un colorante fluorescente intercalante, come bromuro di etidio. </li><li> Purificare il DNA digerito dalla kit estrazione gel e determinare la concentrazione di DNA da uno spettrofotometro misurando Abs 260 x 50 mg / ml. </li><li> Legare il DNA EmGFP-codifica purificato in 50-100 ng di PET-2F-ZIF con 1 U di T4 DNA Ligase per almeno 1 ora a temperatura ambiente. Per ottenere i migliori risultati, effettuare la reazione di ligazione utilizzando un 6: rapporto molare 1 inserto a vettoriale. </li><li> Scongelare 50 ml di eventuali chimicamente competenti XL-1 blu Escherichia coli su ghiaccio e mescolare delicatamente con 10-20 ng di legatura PET-2F-ZIF-EmGFP. </li><li> Tenere in ghiaccio per 30 min. Urti Riscaldare la miscela a 42 ° C per 90 sec e recuperare le cellule in 2 ml di brodo con Super Optimal Cataboliti rimozione (SOC) per 1 ora a 37 ° C con agitazione. </li><li> Stendere 100 ml di cultura recupero su un brodo lisogenia (LB) piastra di agar con 50 mg / ml kanamicina e incubare O / N a 37 ° C. </li><li> Il giorno seguente, inoculare 6 ml di Super Broth (SB) o di coltura LB contenente 50 ug / ml kanamicina con una colonia dalla piastra di agar LB e cultura O / N a 37 ° C. Nota: Colony PCR utilizzando i primer 5 &#39;XmaI-EmGFP e 3&#39; SacI-EmGFP potrebbe essere utilizzata per identificare cloni positivi prima miniprep. </li><li> Purificare pET-2F-ZIF-EmGFP da miniprep e confermare plasmide dal sequenziamento del DNA utilizzando promotore T7 (5&#39;-TAATACGACTCACTATAGGG-3 &#39;). </li></ol> 2. Espressione e purificazione <ol><li> Scongelare 50 ml di chimicamente competente BL21 E. coli su ghiaccio e mescolare delicatamente con 100 ng di PET-2F-ZIF-EmGFP plasmid. Trasforma come descritto nei passaggi 1,7-1,8. </li><li> Il giorno seguente, inoculare 10 ml di terreno LB contenente 50 mg / ml kanamicina con una singola colonia e crescere O / N a 37 ° C con agitazione. </li><li> Il giorno seguente, diluire i 10 ml di O / N cultura in 1 l di terreno LB integrata con 50 mg / ml kanamicina, 0,2% di glucosio e 100 micron ZnCl 2. Crescere la coltura a 37 ° C con agitazione ad una densità ottica a 600 nm (OD 600) di 0,8 e indurre l&#39;espressione di proteine ​​con 2 mM isopropil-β-D-1-thiogalactopyranoside (IPTG). Dopo 6 ore di crescita a 37 ° C, le cellule raccolto per centrifugazione a 5.000 xg per 10 min a 4 ° C. Nota: Le condizioni induzione sono molto variabili e dipendono dalla stabilità delle proteine ​​espressi. Monitorare l&#39;OD 600 ogni 30 minuti fino a quando un OD 600 di 0,8 è raggiunto. </li><li> Risospendere il pellet di cellule in 5 ml di tampone di lisi (50 mM Tris-HCl, NaCl 500 mM, 100 mM ZnCl 2, 1 mM ditiotreitolo (DTT), 1 mM MgCl 2, 1 mM phenylmethylsulfonyl fluoruro (PMSF) e imidazolo 10 mM, pH 8,0). Lisare le cellule sul ghiaccio di ultrasuoni con la seguente impostazione: uscita di potenza del 50%, 4 min di tempo di processo con 5 sec su / 10 sec off intervalli. Evitare il surriscaldamento della soluzione. </li><li> Centrifugare il lisato cellulare a 25.000 xg per 30 min a 4 ° C e trasferire il surnatante in una provetta di raccolta fresco. Per ottenere i migliori risultati, eseguire le seguenti operazioni a 4 ° C. </li><li> Eseguire il surnatante con una colonna pre-compresso con 1 ml di equilibrata liquami Ni-NTA. Lavare la resina con 20 ml di tampone di lavaggio (50 mM Tris-HCl, NaCl 500 mM, 100 mM ZnCl 2, 1 mM DTT, 1 mM MgCl 2 e imidazolo 30 mM, pH 8,0). </li><li> Eluire la proteina con 5 ml di tampone di eluizione (50 mM Tris-HCl, NaCl 500 mM, 100 mM ZnCl 2, 1 mM DTT, 1 mM MgCl 2, e imidazolo 300 mM, pH 8,0). </li><li> Buffer scambiare la proteina eluita con tampone di stoccaggio (50 mMTris-HCl, NaCl 500 mM, 100 mM ZnCl 2, 1 mM DTT, 1 mM MgCl 2 e 10% glicerolo, pH 8,0) e concentrare la proteina di almeno 40 mM usando un concentratore rotazione mediante centrifugazione secondo le istruzioni del produttore. </li><li> Determinare la concentrazione di proteine ​​da BCA o saggio Bradford. Mescolare 2 ml di proteine ​​purificate con 2 ml 2 × SDS-PAGE loading dye, ebollizione a 95 ° C per 10 minuti e poi risolvere il 4% -20% Tris-Glycine SDS-PAGE per valutare la proteina purezza (Figura 2). </li></ol> 3. Protein bagagli <ol><li> Aliquota la proteina concentrata, flash congelare in azoto liquido e conservare a -80 ° C. Per proteine ​​di fusione EmGFP, coprire il tubo con un foglio di alluminio per proteggere la proteina dalla luce. </li><li> Evitare congelamenti e scongelamenti ripetuti della soluzione proteica. Nota: le proteine ​​Zif-fuse sono stabili in queste condizioni per almeno 1 mese. O&gt; 4 stoccaggio inappropriato mese può portarealle proteine ​​precipitazione o photobleaching di EmGFP. </li></ol> 4. proteina di trasduzione <ol><li> Mantenere cellule HeLa in terreno Eagle modificato di Dulbecco (DMEM) contenente 10% (v / v) di siero fetale bovino (FBS) e 1% di antibiotico-antimicotico a 37 ° C in un ambiente completamente umidificata con 5% di CO 2. Nota: Le celle diversi passaggi più di 30 volte non sono raccomandati per la proteina di trasduzione. </li><li> Pre-coat una piastra a 24 pozzetti con 500 ml di 50 mg / ml di poli-lisina per 30 a 60 minuti a 25 ° C. Cellule Seed su una piastra da 24 pozzetti ad una densità di 2 x 10 5 cellule per pozzetto. A 24 ore dopo la semina, o una volta cellule sono tra l&#39;80% -90% confluenti, rimuovere i supporti da ciascun pozzetto e lavare con 500 ml di pre-riscaldato DMEM senza siero (SFM). </li><li> Per ogni bene, aggiungere 250 ml di SFM contenente 2 mM di proteine ​​Zif-EmGFP e 100 micron ZnCl 2. Incubare le cellule a 37 ° C per 1 ora. Nota: i domini ZIF entrano nelle cellule primarily attraverso macropinocitosi, 34 che è un meccanismo di energia-dipendente. Pertanto, le cellule devono essere incubate a 37 ° C per un efficiente internalizzazione proteine. </li><li> Rimuovere supporti dalle cellule e lavare tre volte con 500 ml di calcio-magnesio e senza tampone fosfato salino di Dulbecco (DPBS) supplementato con 0,5 mg / ml di eparina. Nota: L&#39;eparina è necessario rimuovere legato alle proteine ​​di superficie che potrebbe complicare le analisi a valle. </li><li> (Opzionale) Ripetere i trattamenti fino a tre volte per la consegna maggiore. </li><li> Isolare cellule trattate immediatamente dopo eparina lavaggio mediante digestione con 0,05% tripsina-EDTA a 37 ° C per 2 min. Risospendere le cellule staccate in 0,5 ml di DPBS addizionato con 1% FBS. </li><li> Misurare l&#39;intensità di fluorescenza di ciascun campione mediante citometria di flusso 35 utilizzando il canale di isotiocianato di fluoresceina (FITC) (Figura 3). Regolare il forward scatter (FSC) e side scatter (SSC) per posizionare la popolazioneinteressi su scala, assicurando che le popolazioni con proprietà differenti vengono risolte tra loro. </li><li> Raccogliere 10.000 eventi live per ogni campione e analizzare i dati in citometria a flusso di analisi dei dati del software. 36 Normalizzare fluorescenza da cellule HeLa trattate con ZIF EmGFP a quelle cellule trattate solo con SFM. </li></ol>

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Qui, un protocollo di step-by-step per la consegna delle proteine ​​usando zinc-finger (ZIF) domini cellulari permeabili è presentato. Il dominio ZIF non riduce l&#39;attività del fuso carico enzimatica 34; consente la produzione e purificazione di proteine ​​dei rendimenti quasi identici a quelli osservati con proteine ​​non modificato; e può trasportare proteine ​​ed enzimi in una vasta gamma di tipi di cellule con efficienze superiori peptide o proteina sistemi tradizionali dominio trasd...

Altamente strategie consegna proteine ​​efficienti e versatili sono fondamentali per molti la ricerca di base e applicazioni terapeutiche. La consegna diretta di proteine ​​purificate in cellule rappresenta uno dei metodi più sicuri e più semplici per raggiungere questo. 1,2 differenza strategie che si basano su espressione genica da acidi nucleici, proteine ​​3-5 consegna non comporta alcun rischio di mutagenesi inserzionale, è indipendente dal cellular trascrizione macchinari e / definizione permette un effetto immediato. Tuttavia, la mancanza di metodi semplici e generalizzabili per dotare l&#39;attività delle cellule-penetrante su proteine ​​confonde regolarmente il loro ingresso diretto nelle cellule. Gli attuali metodi per facilitare la consegna proteina intracellulare si basano sull&#39;uso di naturalmente 6-8 o progettati peptidi cellula-penetranti, 9-12 domini di trasduzione sovralimentati, 13,14 nanoparticelle 15 e liposomi, 16 particelle simili al virus 17,18 </sup&gt; materiali polimerici microsfere. 19 Purtroppo, molti di questi approcci sono ostacolati da bassi tassi di assorbimento cellulare, 20,21 scarsa stabilità, 22 involontaria tipo cellulare specificità, 23 basso endosomali proprietà di fuga di 24 e la tossicità. 25 Inoltre, molti proteine ​​e tecnologie di trasduzione riducono la bioattività delle proteine ​​consegnati. 14 Il nostro laboratorio in precedenza dimostrato che zinc-finger nucleasi (ZFN) proteine ​​- restrizione endonucleasi chimerico costituito da una Cys 2 -Il suo 2 zinc-finger proteina-DNA-binding programmabile e il dominio scissione del FokI endonucleasi di restrizione 26-28 - sono intrinsecamente cell- permeabile. 29 L&#39;attività delle cellule-penetrante sorprendente ha dimostrato di essere una proprietà intrinseca del dominio zinc-finger design personalizzato, una piattaforma di legame al DNA che è emersa come un potente strumento per la mirata del genoma enEngineering, 30-32 e considerato il risultato della costellazione di sei residui carichi positivamente sulla superficie della proteina. Infatti, diverse proteine ​​che legano il DNA, tra cui c-Jun e N-DEK hanno dimostrato di possedere una capacità innata di attraversare le membrane cellulari. 33 Più recentemente, il nostro laboratorio espanso su questi risultati e dimostrato che l&#39;attività delle cellule-penetrante di zinco finger (ZIF) domini potrebbero essere sfruttate per la consegna delle proteine ​​intracellulari. La fusione genetica di entrambi i domini ZIF uno o due dita per uno specifico carico di proteine ​​portato ad assorbimento di efficienza che hanno superato molti sistemi di consegna di peptidi cellula-penetranti convenzionali. 34 In particolare, la consegna Zif-mediata non ha compromesso l&#39;attività di carico enzimatica fuso e facilitato alti livelli di consegna citosolico. Collettivamente, questi risultati dimostrano il potenziale del dominio ZIF per facilitare la consegna efficiente e facile delle proteine, e potenzialmente più diversi tipi di macromolecole, nelle cellule. Qui, un protocollo dettagliato passo-passo su come implementare la tecnologia ZIF per la consegna delle proteine ​​in cellule di mammifero è presentato. Abbiamo già costruito una suite di uno, due, tre, quattro, cinque e sei dita domini ZIF che non hanno la capacità di legare il DNA, a causa della sostituzione di ciascuno dei DNA-binding residui α-elica, ma sono in grado di fornire proteine ​​in cellule 34 (Figura 1). La produzione e la trasduzione di Emerald GFP (EmGFP) in cellule HeLa utilizzando una Zif dominio a due dita è descritto. Questo protocollo è estensibile a quasi qualsiasi proteina in grado di espressione solubile in Escherichia coli e quasi ogni tipo di cellula di mammifero. I risultati attesi sono forniti e strategie per massimizzare le prestazioni di questo sistema vengono anche discussi.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>XmaI</td>
			<td>New England Biolabs</td>
			<td>R0180L</td>
			<td></td>
		</tr>
		<tr>
			<td>SacI</td>
			<td>New England Biolabs</td>
			<td>R0156L</td>
			<td></td>
		</tr>
		<tr>
			<td>Expand High Fidelity PCR system</td>
			<td>Roche</td>
			<td>11759078001</td>
			<td></td>
		</tr>
		<tr>
			<td>dNTPs</td>
			<td>New England Biolabs</td>
			<td>N0446S</td>
			<td></td>
		</tr>
		<tr>
			<td>4-20% Tris-Glycine Mini protein gels, 1.5 mm, 10 wells</td>
			<td>Life Technologies</td>
			<td>EC6028BOX</td>
			<td></td>
		</tr>
		<tr>
			<td>2x Laemmli Sample Buffer</td>
			<td>BioRad</td>
			<td>161-0737</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA Ligase</td>
			<td>Life Technologies</td>
			<td>15224-017</td>
			<td></td>
		</tr>
		<tr>
			<td>BL21 (DE3) Competent E. coli</td>
			<td>New England Biolabs</td>
			<td>C2527I</td>
			<td></td>
		</tr>
		<tr>
			<td>IPTG</td>
			<td>Thermo Scientific</td>
			<td>R0391</td>
			<td></td>
		</tr>
		<tr>
			<td>Zinc Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>208086-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Kanamycin Sulfate</td>
			<td>Fisher Scientific</td>
			<td>BP906-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G8270-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Fisher Scientific</td>
			<td>BP152-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>S9888-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>DTT</td>
			<td>Fisher Scientific</td>
			<td>PR-V3151&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>PMSF</td>
			<td>Thermo Scientific</td>
			<td>36978</td>
			<td></td>
		</tr>
		<tr>
			<td>Ni-NTA Agarose Resin</td>
			<td>QIAGEN</td>
			<td>30210</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma-Aldrich</td>
			<td>G5516-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Imidazole</td>
			<td>Sigma-Aldrich</td>
			<td>I5513-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Amicon Ultra-15 Centrifugal Filter Units</td>
			<td>EMO Millipore</td>
			<td>UFC900324</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Life Technologies</td>
			<td>11966-025</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Life Technologies</td>
			<td>10437-028</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic&#160;</td>
			<td>Life Technologies</td>
			<td>15240-062</td>
			<td></td>
		</tr>
		<tr>
			<td>24-Well Flat Bottom Plate</td>
			<td>Sigma-Aldrich</td>
			<td>CLS3527-100EA</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-Lysine</td>
			<td>Sigma-Aldrich</td>
			<td>P7280</td>
			<td></td>
		</tr>
		<tr>
			<td>DPBS, No Calcium, No Magnesium</td>
			<td>Life Technologies</td>
			<td>21600010</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparan Sulfate</td>
			<td>Sigma-Aldrich</td>
			<td>H4777</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Life Technologies</td>
			<td>25300054</td>
			<td></td>
		</tr>
		<tr>
			<td>Hela cells</td>
			<td>ATCC</td>
			<td>CCL-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Nano Drop ND-1000 spectrophotometer&#160;</td>
			<td>Thermo Fisher Scientific</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAquick PCR Purification Kit</td>
			<td>QIAGEN</td>
			<td>28104</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAquick Gel Extraction Kit</td>
			<td>QIAGEN</td>
			<td>28704</td>
			<td></td>
		</tr>
	</tbody>
</table>

direct protein delivery to mammalian cells using cell-permeable cys2-his2 zinc-finger domains

Due to their modularity and ability to be reprogrammed to recognize a wide range of DNA sequences, Cys2-His2 zinc-finger DNA-binding domains have emerged as useful tools for targeted genome engineering. Like many other DNA-binding proteins, zinc-fingers also possess the innate ability to cross cell membranes. We recently demonstrated that this intrinsic cell-permeability could be leveraged for intracellular protein delivery. Genetic fusion of zinc-finger motifs leads to efficient transport of protein and enzyme cargo into a broad range of mammalian cell types. Unlike other protein transduction technologies, delivery via zinc-finger domains does not inhibit enzyme activity and leads to high levels of cytosolic delivery. Here a detailed step-by-step protocol is presented for the implementation of zinc-finger technology for protein delivery into mammalian cells. Key steps for achieving high levels of intracellular zinc-finger-mediated delivery are highlighted and strategies for maximizing the performance of this system are discussed.

Due dita proteine ​​di fusione Zif-EmGFP possono essere espressi in E. coli con&gt; 95% omogeneità e rese elevate (&gt; 25 mg / ml) (Figura 2). In generale, a uno o due dita proteine ​​di fusione ZIF possono essere prodotti in quantità quasi identiche a quelle del wild-type di proteine ​​non modificato. Tuttavia, in alcuni contesti, proteine ​​di fusione ZIF cinque e sei dita sono in grado di essere prodotti in rendimenti abbastanza elevati per applicazioni a valle. <p cla...

Watch this Scientific Journal Video about Direct Protein Delivery to Mammalian Cells Using Cell-permeable Cys2-His2 Zinc-finger Domains at JoVE.com

Direct Protein Delivery to Mammalian Cells Using Cell-permeable Cys2-His2 Zinc-finger Domains

Domini zinco-dita sono intrinsecamente cellula-permeabile e capace di mediare consegna proteine ​​in una vasta gamma di tipi di cellule di mammifero. Qui, un protocollo dettagliato passo-passo per l&#39;attuazione tecnologia zinc finger-consegna proteina intracellulare è presentato.

Diretto Protein Consegna a cellule di mammifero Utilizzando Cell-permeabile Cys<sub&gt; 2</sub&gt; -Il suo<sub&gt; 2</sub&gt; domini zinc-finger

Due to their modularity and ability to be reprogrammed to recognize a wide range of DNA sequences, Cys2-His2 zinc-finger DNA-binding domains have emerged ...

direct-protein-delivery-to-mammalian-cells-using-cell-permeable-cys2

Research

JoVE Journal

Biology

Direct Protein Delivery to Mammalian Cells Using Cell-permeable Cys2-His2 Zinc-finger Domains

9.8K Views.  The Scripps Research Institute.  Domini zinco-dita sono intrinsecamente cellula-permeabile e capace di mediare consegna proteine ​​in una vasta gamma di tipi di cellule di mammifero. Qui, un protocollo dettagliato passo-passo per l'attuazione tecnologia zinc finger-consegna proteina intracellulare è presentato. 

Video: Direct Protein Delivery to Mammalian Cells Using Cell-permeable Cys2-His2 Zinc-finger Domains

Long-term Imaging Mammalian Cells using Wide-Field Microscopy

A lungo termine Imaging cellule di mammifero utilizzando Wide-Field Microscopia

Ricerca

Biologia

Trypsinizing and Subculturing Mammalian Cells

As cells reach confluency, they must be subcultured or passaged. Failure to subculture confluent cells results in reduced mitotic index and eventually in cell death. The first step in subculturing is to detach cells from the surface of the primary culture vessel by trypsinization or mechanical means. The resultant cell suspension is then subdivided, or reseeded, into fresh cultures. Secondary cultures are checked for growth and fed periodically, and may be subsequently subcultured to produce tertiary cultures. The time between passaging of cells varies with the cell line and depends on the growth rate.

As cells reach confluency, they must be subcultured or passaged. This video will demonstrate a procedure for subculturing both adherent and suspension cells.

Trypsinizing e Trapianto cellule di mammifero

As cells reach confluency, they must be subcultured or passaged. Failure to subculture confluent cells results in reduced mitotic index and eventually in ...

Engineering Cell-permeable Protein

The protein transduction technique enables the direct delivery of biologically active material into mammalian cells [for review see 1,2]. For this one can make use of the translocating ability of so-called cell penetrating peptides (CPPs), also designated as protein transduction domains (PTDs). The TAT-CPP derived from the human immunodeficiency virus type 1 (HIV-1) Tat (trans-activator of transcription) protein has been widely used. The positively charged TAT promotes cell permeability thereby overcoming the barriers of the cellular membrane by endocytosis or/and direct membrane penetration2. In combination with a nuclear localization signal (NLS) fusion proteins are able to enter the nucleus exhibiting functionality. Our video presentation demonstrates, as an exemplification for the engineering of cell-permeable proteins, the construction, production and application of a cell-permeable version of the DNA-modifying enzyme Cre.
Cre is a site-specific recombinase that is able to recognize and recombine 34 base pair loxP sites in mammalian cells in vitro and in vivo. Therefore the Cre/loxP system is widely used to conditionally induce mutations in the genome of living cells3,4. The delivery of active Cre recombinase to cells, however, represents a limitation.
We describe the pSESAME vector system, which allows a direct insertion of the gene-of-interest and provides a platform to rapidly clone different domains and tags used within the vector in a convenient and standardized manner. Rearranging of the different tags has been shown to modify the biochemical properties of the fusion proteins providing a possibility to achieve higher yield and better solubility. We demonstrate how to express and purify recombinant cell-permeant proteins in and from E. coli. The functionality of the recombinant Cre protein is finally validated in cell culture by assessing its intracellular recombinase activity.

Protein transduction enables the direct delivery of biologically active proteins into cells. In contrast to conventional methods such as DNA transfection or viral transduction this non-invasive paradigm allows highly efficient cellular manipulation in a titratable manner circumventing cellular toxicity and the risk of oncogenic transformation by permanent genetic modification.

Ingegneria Cell-permeabile proteine

The protein transduction technique enables the direct delivery of biologically active material into mammalian cells [for review see 1,2]. For this one can ...

Using the GELFREE 8100 Fractionation System for Molecular Weight-Based Fractionation with Liquid Phase Recovery

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based fractionation. The system is comprised of single-use, 8-sample capacity cartridges and a benchtop GELFREE Fractionation Instrument. During separation, a constant voltage is applied between the anode and cathode reservoirs, and each protein mixture is electrophoretically driven from a loading chamber into a specially designed gel column gel. Proteins are concentrated into a tight band in a stacking gel, and separated based on their respective electrophoretic mobilities in a resolving gel. As proteins elute from the column, they are trapped and concentrated in liquid phase in the collection chamber, free of the gel. The instrument is then paused at specific time intervals, and fractions are collected using a pipette. This process is repeated until all desired fractions have been collected. If fewer than 8 samples are run on a cartridge, any unused chambers can be used in subsequent separations.
This novel technology facilitates the quick and simple separation of up to 8 complex protein mixtures simultaneously, and offers several advantages when compared to previously available fractionation methods. This system is capable of fractionating up to 1mg of total protein per channel, for a total of 8mg per cartridge. Intact proteins over a broad mass range are separated on the basis of molecular weight, retaining important physiochemical properties of the analyte. The liquid phase entrapment provides for high recovery while eliminating the need for band or spot cutting, making the fractionation process highly reproducible1.

The accompanying video describes the use of the GELFREE 8100 Fractionation System, which partitions complex protein samples on the basis of molecular weight and recovers the fractions in liquid phase. The video describes how the technology works, how it is used, and provides resultant data, with polyacrylamide gel electrophoresis analysis of fractionated bovine liver homogenate.

Utilizzando il sistema GELFREE 8100 Frazionamento per peso molecolare basata su Frazionamento con recupero della fase liquida

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based ...

Genome Editing with CompoZr Custom Zinc Finger Nucleases (ZFNs)

Genome editing is a powerful technique that can be used to elucidate gene function and the genetic basis of disease. Traditional gene editing methods such as chemical-based mutagenesis or random integration of DNA sequences confer indiscriminate genetic changes in an overall inefficient manner and require incorporation of undesirable synthetic sequences or use of aberrant culture conditions, potentially confusing biological study. By contrast, transient ZFN expression in a cell can facilitate precise, heritable gene editing in a highly efficient manner without the need for administration of chemicals or integration of synthetic transgenes.
Zinc finger nucleases (ZFNs) are enzymes which bind and cut distinct sequences of double-stranded DNA (dsDNA). A functional CompoZr ZFN unit consists of two individual monomeric proteins that bind a DNA "half-site" of approximately 15-18 nucleotides (see Figure 1). When two ZFN monomers "home" to their adjacent target sites the DNA-cleavage domains dimerize and create a double-strand break (DSB) in the DNA.1 Introduction of ZFN-mediated DSBs in the genome lays a foundation for highly efficient genome editing. Imperfect repair of DSBs in a cell via the non-homologous end-joining (NHEJ) DNA repair pathway can result in small insertions and deletions (indels). Creation of indels within the gene coding sequence of a cell can result in frameshift and subsequent functional knockout of a gene locus at high efficiency.2 While this protocol describes the use of ZFNs to create a gene knockout, integration of transgenes may also be conducted via homology-directed repair at the ZFN cut site.
The CompoZr Custom ZFN Service represents a systematic, comprehensive, and well-characterized approach to targeted gene editing for the scientific community with ZFN technology. Sigma scientists work closely with investigators to 1) perform due diligence analysis including analysis of relevant gene structure, biology, and model system pursuant to the project goals, 2) apply this knowledge to develop a sound targeting strategy, 3) then design, build, and functionally validate ZFNs for activity in a relevant cell line. The investigator receives positive control genomic DNA and primers, and ready-to-use ZFN reagents supplied in both plasmid DNA and in-vitro transcribed mRNA format. These reagents may then be delivered for transient expression in the investigator&#x2019;s cell line or cell type of choice. Samples are then tested for gene editing at the locus of interest by standard molecular biology techniques including PCR amplification, enzymatic digest, and electrophoresis. After positive signal for gene editing is detected in the initial population, cells are single-cell cloned and genotyped for identification of mutant clones/alleles.

Genome Editing with CompoZr Custom Zinc Finger Nucleases ZFNs

The CompoZr Custom Zinc-Finger Nuclease (ZFN) Service enables precise genome editing in any organism or cell line at any locus defined by the user. This article describes the process for the design, manufacture, validation and implementation of the CompoZr Custom ZFN Service.

Genome Editing con nucleasi zinco Finger CompoZr personalizzati (ZFNs)

Genome editing is a powerful technique that can be used to elucidate gene function and the genetic basis of disease. Traditional gene editing methods such ...

siRNA Screening to Identify Ubiquitin and Ubiquitin-like System Regulators of Biological Pathways in Cultured Mammalian Cells

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that regulates diverse biological pathways including the hypoxia response, proteostasis, the DNA damage response and transcription.&#160; To better understand how UBLs regulate pathways relevant to human disease, we have compiled a human siRNA &#8220;ubiquitome&#8221; library consisting of 1,186 siRNA duplex pools targeting all known and predicted components of UBL system pathways. This library can be screened against a range of cell lines expressing reporters of diverse biological pathways to determine which UBL components act as positive or negative regulators of the pathway in question.&#160; Here, we describe a protocol utilizing this library to identify ubiquitome-regulators of the HIF1A-mediated cellular response to hypoxia using a transcription-based luciferase reporter.&#160; An initial assay development stage is performed to establish suitable screening parameters of the cell line before performing the screen in three stages: primary, secondary and tertiary/deconvolution screening. &#160;The use of targeted over whole genome siRNA libraries is becoming increasingly popular as it offers the advantage of reporting only on members of the pathway with which the investigators are most interested.&#160; Despite inherent limitations of siRNA screening, in particular false-positives caused by siRNA off-target effects, the identification of genuine novel regulators of the pathways in question outweigh these shortcomings, which can be overcome by performing a series of carefully undertaken control experiments.

Here, we describe a methodology to perform a targeted siRNA &#8220;ubiquitome&#8221; screen to identify novel ubiquitin and ubiquitin-like regulators of the HIF1A-mediated cellular response to hypoxia.&#160; This can be adapted to any biological pathway where a robust read out of reporter activity is available.

siRNA screening per identificare ubiquitina e ubiquitina-come regolatori del sistema di percorsi biologici in cellule di mammifero coltivate

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that ...

Identification of Protein Interaction Partners in Mammalian Cells Using SILAC-immunoprecipitation Quantitative Proteomics

Quantitative proteomics combined with immuno-affinity purification, SILAC immunoprecipitation, represent a powerful means for the discovery of novel protein:protein interactions. By allowing the accurate relative quantification of protein abundance in both control and test samples, true interactions may be easily distinguished from experimental contaminants. Low affinity interactions can be preserved through the use of less-stringent buffer conditions and remain readily identifiable. This protocol discusses the labeling of tissue culture cells with stable isotope labeled amino acids, transfection and immunoprecipitation of an affinity tagged protein of interest, followed by the preparation for submission to a mass spectrometry facility. This protocol then discusses how to analyze and interpret the data returned from the mass spectrometer in order to identify cellular partners interacting with a protein of interest. As an example this technique is applied to identify proteins binding to the eukaryotic translation initiation factors: eIF4AI and eIF4AII.

SILAC immunoprecipitation experiments represent a powerful means for discovering novel protein:protein interactions. By allowing the accurate relative quantification of protein abundance in both control and test samples, true interactions may be easily distinguished from experimental contaminants, and low affinity interactions preserved through use of less-stringent buffer conditions.

Identificazione delle proteine ​​partner di interazione in cellule di mammifero Uso SILAC-immunoprecipitazione quantitativi Proteomica

Quantitative proteomics combined with immuno-affinity purification, SILAC immunoprecipitation, represent a powerful means for the discovery of novel ...

Zinc-finger Nuclease Enhanced Gene Targeting in Human Embryonic Stem Cells

One major limitation with current human embryonic stem cell (ESC) differentiation protocols is the generation of heterogeneous cell populations.&#160;These cultures contain the cells of interest, but are also contaminated with undifferentiated ESCs, non-neural derivatives and other neuronal subtypes.&#160; This limits their use in in vitro and in vivo applications, such as in vitro modeling for drug discovery or cell replacement therapy. To help overcome this, reporter cell lines, which offer a means to visualize, track and isolate cells of interest, can be engineered.&#160;However, to achieve this in human embryonic stem cells via conventional homologous recombination is extremely inefficient.&#160;This protocol describes targeting of the Pituitary homeobox 3 (PITX3) locus in human embryonic stem cells using custom designed zinc-finger nucleases, which introduce site-specific double-strand DNA breaks, together with a PITX3-EGFP-specific DNA donor vector. Following the generation of the PITX3 reporter cell line, it can then be differentiated using published protocols for use in studies such as in vitro Parkinson&#8217;s disease modeling or cell replacement therapy.

Reporter cell lines offer a means to visualize, track and isolate cells of interest from heterogeneous populations.&#160;However, gene-targeting using conventional homologous recombination in human embryonic stem cells is extremely inefficient. Herein, we describe targeting CNS midbrain specific transcription factor PITX3 locus with EGFP using zinc-finger nuclease enhanced homologous recombination.

Zinc-finger nucleasi avanzata gene targeting in cellule staminali embrionali umane

One major limitation with current human embryonic stem cell (ESC) differentiation protocols is the generation of heterogeneous cell ...

Examination of Proteins Bound to Nascent DNA in Mammalian Cells Using  BrdU-ChIP-Slot-Western Technique

Histone deacetylases 1 and 2 (HDAC1,2) localize to the sites of DNA replication. In the previous study, using a selective inhibitor and a genetic knockdown system, we showed novel functions for HDAC1,2 in replication fork progression and nascent chromatin maintenance in mammalian cells. Additionally, we used a BrdU-ChIP-Slot-Western technique that combines chromatin immunoprecipitation (ChIP) of bromo-deoxyuridine (BrdU)-labeled DNA with slot blot and Western analyses to quantitatively measure proteins or histone modification associated with nascent DNA.
Actively dividing cells were treated with HDAC1,2 selective inhibitor or transfected with siRNAs against Hdac1 and Hdac2 and then newly synthesized DNA was labeled with the thymidine analog bromodeoxyuridine (BrdU). The BrdU labeling was done at a time point when there was no significant cell cycle arrest or apoptosis due to the loss of HDAC1,2 functions. Following labeling of cells with BrdU, chromatin immunoprecipitation (ChIP) of histone acetylation marks or the chromatin-remodeler was performed with specific antibodies. BrdU-labeled input DNA and the immunoprecipitated (or ChIPed) DNA was then spotted onto a membrane using the slot blot technique and immobilized using UV. The amount of nascent DNA in each slot was then quantitatively assessed using Western analysis with an anti-BrdU antibody. The effect of loss of HDAC1,2 functions on the levels of newly synthesized DNA-associated histone acetylation marks and chromatin remodeler was then determined by normalizing the BrdU-ChIP signal obtained from the treated samples to the control samples.

In this protocol, we describe a novel BrdU-ChIP-Slot-Western technique to examine proteins and histone modifications associated with newly synthesized or nascent DNA.

Esame di proteine ​​legate al DNA Nascente in cellule di mammifero utilizzando la tecnica BrdU-chip-Slot-occidentale

Histone deacetylases 1 and 2 (HDAC1,2) localize to the sites of DNA replication. In the previous study, using a selective inhibitor and a genetic ...

A Graphical User Interface for Software-assisted Tracking of Protein Concentration in Dynamic Cellular Protrusions

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex signaling mechanisms underlying filopodial initiation, elongation and subsequent stabilization or retraction, it is crucial to determine the spatio-temporal protein activity in these dynamic structures. To analyze protein function in filopodia, we recently developed a semi-automated tracking algorithm that adapts to filopodial shape-changes, thus allowing parallel analysis of protrusion dynamics and relative protein concentration along the whole filopodial length. Here, we present a detailed step-by-step protocol for optimized cell handling, image acquisition and software analysis. We further provide instructions for the use of optional features during image analysis and data representation, as well as troubleshooting guidelines for all critical steps along the way. Finally, we also include a comparison of the described image analysis software with other programs available for filopodia quantification. Together, the presented protocol provides a framework for accurate analysis of protein dynamics in filopodial protrusions using image analysis software.

We present a software solution for semi-automated tracking of relative protein concentration along the length of dynamic cellular protrusions.

Un&#39;interfaccia utente grafica per il monitoraggio assistito della concentrazione di proteine ​​in protrusioni cellulari dinamiche

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex ...