Wir danken James Clark für die Bereitstellung Figuren von Tieren in verschiedenen Entwicklungs-Zeitpunkten. C. elegans-Stämme in dieser Studie wurden vom Caenorhabditis Genetics Center, das durch die NIH National Center for Research Resources (NCRR) getragen wird erhalten. Diese Arbeit wurde von CIRG 1817 vom CUNY JL und CSD unterstützt und durch NIH 1R15GM073678-01 und 1R15GM097692-01 bis CSD Wir danken Dr. William J Rice, Dr. Nathalia Holtzman und Melissa Silvestrini für Kommentare zum Manuskript. Diese Arbeit wurde in teilweiser Erfüllung der Anforderungen für eine Promotion an der Graduate Center der City University of New York (S. Xiong) durchgeführt.

Ein. Vorbereiten RNAi Feeding Plates Tragen Zielgensequenz <ol><li> Bei der Verwendung von kommerziell erhältlichen RNAi-Bibliotheken (zB von Quelle BioScience LifeSciences), fahren Sie mit Schritt 1.4. Alternativ klonen Target-Gensequenzen in Vektor L4440, ein häufig verwendetes Wurm RNAi Plasmid 8, Standard-Klonen Protokoll. </li><li> Verwandeln Sie das rekombinante Plasmid in Bakterienstamm HT115 (DE3), Kultur sie auf LB-Agar-Platten mit 25 ug / ml Carbenicillin und 12,5 pg / ml Tetracyclin, und wählen Sie einen einzigen Klon für die zukünftige Verwendung. </li><li> Unterdessen transformieren Leervektor L4440 in Bakterienstamm HT115 als Kontrolle für die Experimente verwendet. </li><li> Kultur sowohl rekombinante und leer L4440-tragenden Bakterien in 1 ml LB-Medium mit 100 ug / ml Ampicillin über Nacht bei 37 ° C. Tetracyclin nicht hinzugefügt wird aufgrund der Tatsache, dass es RNAi Effizienz abnimmt. </li><li> Weitere 5 ml LB-Medium mit 100 ug / ml Ampicillin in die Nacht culture, für etwa 4-6 h bei 37 ° C. </li><li> Seed 0,5 ml rekombinanten oder leer L4440 tragenden Bakterienkultur auf die RNAi-Wurm Platten. Beschriften Sie alle Platten mit Klon Namen. </li><li> Markieren Sie die Platten und Inkubation über Nacht bei 37 ° C bis Bakterienrasen wachsen, das sind die RNAi Platten mit oder ohne Ziel Gensequenz. Mindestens 2 Platten sollten für jede Bedingung vorbereitet werden. </li></ol> 2. Kultur Worms auf den RNAi Feeding Plates <ol><li> Flamme sterilisieren die Spitze eines Platin Drahtwurm Wahl. Verwenden Sie den Wurm holen zu holen 6-10 vierten Larvenstadium (L4) Zwitter jedem RNAi Platte, die entweder rekombinante oder leer L4440 enthält; die Tiere werden die Bakterien als Nahrungsquelle zu nutzen. </li><li> Lassen Hermaphroditen bei 20 ° C (ein Standard-Kulturbedingungen für C. elegans) über Nacht wachsen, werden sie als junge Erwachsene am nächsten Tag. </li><li> Übertragen 6-10 jungen Erwachsenen in einer neuen entsprechend gekennzeichnet und vorbereitet RNAi Platte. </li><li> Lassen Sie dieErwachsene legen Eier für 4-6 Stunden, dann entfernen Sie alle Erwachsenen von der Platte; dieser Schritt ist, um die Nachkommenschaft zu synchronisieren. Sobald die Mütter entfernt werden, beginnen zu zählen. Dies ist zeit Null. </li><li> Die Inkubation bei 20 ° C zu lassen Tieren zu bestimmten Entwicklungsstadium wachsen; in diesem Protokoll, wählen wir junge Erwachsene für phänotypische Analyse. Für Niederschlägen, die in einem normalen Tempo zu entwickeln, ist 72-stündigen Inkubation ausreichend für die Tiere zu jungen Erwachsenen geworden. Allerdings wirken sich verschiedene Gene tierischen Entwicklung anders. Wenn RNAi verursacht Tiere mit einer anderen Rate wachsen, können junge Erwachsene wie die nicht mehr als 24 Stunden letzten L4 werden mit abgeschlossener Vulva Entwicklung und 2-6 Embryonen in die Gebärmutter (wenn fruchtbaren) identifiziert. Um andere Entwicklungsstadien zu erkennen, sollte der Prüfer Gonaden und Vulva Entwicklung als Leitfaden verwenden. </li></ol> 3. Ergebnis Body Size Phänotypen der RNAi behandelt Worms <ol><li> Zeigen zwei Schichten von farbigen Etikettenbänder auf einem Glasträger. Machen Sie zwei derse Glasträger. Dann legen Sie eine neue Glasplatte zwischen den beiden Folien mit Klebeband. Melt 2% Agarose in Wasser; einen Tropfen in die Mitte des neuen Glasträger; drücken Sie dann die zweite Glasplatte auf der Oberseite eine dünne Schicht von 2% Agarose wie zuvor beschrieben 9 machen. </li><li> Sobald Agarose verfestigt wird, entfernen Sie die obere Glasplatte; der Schlitten mit Agarose-Pad ist bereit, Würmer zu laden. Label slide mit Klon Namen. </li><li> Fügen Sie 10 ul 25 mM NaN 3 zu dem Agarose-Pad; holen 30-40 Tiere in die NaN 3-Lösung, um sie zu immobilisieren; dann legte Deckglas auf der Oberseite; wiederholen sowohl für rekombinante und leer L4440 tragenden RNAi-behandelten Tieren. </li><li> Bild die Würmer unter Binokular mit 2.5x Objektiv; hier benutzen wir Leica Digitalkamera mit unterstützender Software Qcapture. </li><li> Zur Kalibrierung ersten Aufnehmen eines Bildes eines Standard-Mikrometer-Herrscher. Dann öffnen Sie das Bild in Image-Pro Software, die auf &quot;Messen&quot; klicken und wählen Sie &quot;Kalibrierung&quot; und wählen Sie dann&quot;Spatial Calibration Wizard&quot;. Mit &quot;kalibrieren das aktive Bild&quot; gewählt haben, auf &quot;weiter&quot; klicken. Geben Sie den Namen für die Kalibrierung und sicherzustellen, dass die Raumbezug Einheiten Mikrometer eingestellt sind. Dann überprüfen Sie die &quot;eine Referenz Kalibrierung&quot; und klicken Sie auf &quot;weiter&quot;. Klicken Sie auf &quot;draw Bezugslinie.&quot; Ein Verweis Maßstab erscheint. Neupositionierung des Maßstabsbalken, um die Enden des Mikrometers übereinstimmen, dann zeigen, dass die Referenz 1.000 Einheiten anzeigt. Klicken Sie auf &quot;OK&quot;, &quot;Weiter&quot; und &quot;Fertigstellen&quot;. </li><li> Sobald die Software kalibriert ist, öffnet sich ein Wurm Bild. Dann, unter dem Menü &quot;Messen&quot;, wählen Sie &quot;Kalibrierung&quot; und klicken Sie auf &quot;select räumliche&quot;. In dem Pull-Down-Menü wählen Sie den Dateinamen für die Mikrometerkalibriervorrichtung erstellt. Dann, unter dem Menü &quot;Messen&quot;, wählen Sie &quot;Messungen.&quot; In dem sich öffnenden Fenster wählen Sie die freie Zeichnen Werkzeug und eine Linie durch die Mitte des tierischen Körpers von Kopf bis Schwanz mit Computer-Maus (Abbildung 1). Die Länge wird im Fenster anzuzeigen. JetztSie haben zwei Gruppen von Daten: Rumpflänge von Tieren mit Zielgen RNAi und Kontrolltieren mit leeren L4440 Vektor behandelt wurden. </li><li> Exportieren Sie die Längenmessung in eine Microsoft Excel-Datei, oder einem anderen geeigneten statistischen Software. Analyse der Daten durch die Berechnung der Mittelwert und die Standardabweichung für jede Probe. Dann vergleichen Sie Proben mittels Student-t-Test. </li></ol>

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	<li>Melnyk, C. W., Molnar, A., Baulcombe, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intercellular+and+systemic+movement+of+RNA+silencing+signals.">Intercellular and systemic movement of RNA silencing signals.</a> Embo J. 30, 3553-3563 (2011).</li><li>Wall, N. R., Shi, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+RNA:+can+RNA+interference+be+exploited+for+therapy.">Small RNA: can RNA interference be exploited for therapy.</a> Lancet. 362, 1401-1403 (2003).</li><li>Kalantidis, K., Schumacher, H. T., Alexiadis, T., Helm, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+silencing+movement+in+plants.">RNA silencing movement in plants.</a> Biol. Cell. 100, 13-26 (2008).</li><li>Shim, M. 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S., Ahringer, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome-wide+RNAi+screening+in+Caenorhabditis+elegans.">Genome-wide RNAi screening in Caenorhabditis elegans.</a> Methods. 30, 313-321 (2003).</li><li>Savage-Dunn, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+screen+for+small+body+size+mutants+in+C.+elegans+reveals+many+TGFb+pathway+components.">Genetic screen for small body size mutants in C. elegans reveals many TGFb pathway components.</a> Genesis. 35, 239-247 (2003).</li><li>Timmons, L., Fire, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specific+interference+by+ingested+dsRNA.">Specific interference by ingested dsRNA.</a> Nature. 395, 854 (1998).</li><li>Sulston, J. 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Biol. 56, 110-156 (1977).</li><li>Wang, J., Tokarz, R., Savage-Dunn, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+expression+of+TGF&#946;+signal+transducers+in+the+hypodermis+regulates+body+size+in+C.+elegans.">The expression of TGF&#946; signal transducers in the hypodermis regulates body size in C. elegans.</a> Development. 129, 4989-4998 (2002).</li><li>Liang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Caenorhabditis+elegans+schnurri+homolog+sma-9+mediates+stage-+and+cell+type-specific+responses+to+DBL-1+BMP-related+signaling.">The Caenorhabditis elegans schnurri homolog sma-9 mediates stage- and cell type-specific responses to DBL-1 BMP-related signaling.</a> Development. 130, 6453-6464 (2003).</li><li>Savage-Dunn, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TGF-&#946;+signaling.">TGF-&#946; signaling.</a> WormBook. , 1-12 (2005).</li><li>Simmer, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loss+of+the+putative+RNA-directed+RNA+polymerase+RRF-3+makes+C.+elegans+hypersensitive+to+RNAi.">Loss of the putative RNA-directed RNA polymerase RRF-3 makes C. elegans hypersensitive to RNAi.</a> Curr. Biol. 12, 1317-1319 (2002).</li><li>Wang, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Somatic+misexpression+of+germline+P+granules+and+enhanced+RNA+interference+in+retinoblastoma+pathway+mutants.">Somatic misexpression of germline P granules and enhanced RNA interference in retinoblastoma pathway mutants.</a> Nature. 436, 593-597 (2005).</li><li>De Robertis, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evo-devo:+variations+on+ancestral+themes.">Evo-devo: variations on ancestral themes.</a> Cell. 132, 185-195 (2008).</li><li>Timmons, L., Court, D. L., Fire, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ingestion+of+bacterially+expressed+dsRNAs+can+produce+specific+and+potent+genetic+interference+in+Caenorhabditis+elegans.">Ingestion of bacterially expressed dsRNAs can produce specific and potent genetic interference in Caenorhabditis elegans.</a> Gene. 263, 103-112 (2001).</li></ol>

Keine Interessenskonflikte erklärt.

In diesem Protokoll beschreiben wir unsere Methode zur Identifizierung von Körpergröße Defektmutanten von C. elegans durch RNAi Fütterung. Dieses Verfahren ist anwendbar auf die Identifizierung von TGF-β-Signalisierung Komponenten. Da diese Komponenten stark durch Evolution 15 konserviert sind, sind solche Bildschirme relevant zur Aufklärung der molekularen Mechanismen der TGF-β-Signalisierung in allen Metazoen. Eine wichtige Überlegung bei der Gestaltung eines solchen Bildschirms ist der Aus...

<table border="1"><tbody><tr><td></td><td></td><td></td><td> RNAi-Wurm Platten 17,7 g Worm Medium Mix 60 g Agar Hinzufügen H 2 O bis 3 Liter. Autoklavieren. 3 ml 1M IPTG (steril) und 3 ml 25 mg / ml Carbenicillin (steril), dann gießen Sie in 60 mm Petrischalen. Worm Platten 17,7 g Worm Medium Mix 0,6 g Streptomycinsulfat 60 g Agar Hinzufügen H 2 O bis 3 Liter. Autoklavieren. Gießen Sie in 60 mm Petrischalen. Worm Medium Mix 55 g Tris-Cl 24 g Tris-OH 310 g Bacto Peptone 800 mg Cholesterin 200 g NaCl Gründlich mischen und achten Sie darauf, Stücke zu vermeiden, das pulverisierte Mischung kann für viele Monate vor der Verwendung gelagert werden. 2% Agarose 0,5 g Agarose Anzeiged 25 ml dH 2 O. Hitze in der Mikrowelle bis zur Auflösung. 1M Isopropyl β-D-1-thiogalactopyranosid (IPTG) 2 g IPTG Lösen in10 ml dH 2 O 1M NaN 3 6,5 g NaN 3 Hinzufügen dH 2 O auf 100 ml 25 mM NaN 3 2,5 ml 1M NaN 3 Hinzufügen dH 2 O auf 100 ml Caenorhabditis elegans aus Caenorhabditis Genetics Center L4440 Plasmid (trägt Ampicillinresistenzgen) Bakterien-Stamm HT115 (DE3) (enthält IPTG induzierbaren T7-Polymerase; defizient für RNAse III-Gen (a dsRNAse), das auch für Tetracyclin-Resistenz-Gen) 16 60 mm Petrischalen 100 mm Petrischalen 14 ml Rundkolben Falcon Kulturröhrchen Glasobjektträger Deckgläschen 1-20 ul Pipette 20-200 ul Pipette 200-1000 ulPipette 1-200 ul Pipettenspitzen 200-1000 ul Pipettenspitzen 1,5 ml Eppendorf-Röhrchen Platindraht Wurm Pick </td></tr></tbody></table>

using rna-mediated interference feeding strategy to screen for genes involved in body size regulation in the nematode c. elegans

Doppel-Strang-RNA-Interferenz (RNAi) ist eine effektive Strategie, um knock down Zielgenexpression 1-3. Es wurde in viele Modellsysteme einschließlich Pflanzen, Wirbellosen und Wirbeltieren angewendet worden. Es gibt verschiedene Methoden, um RNAi in vivo 4,5 zu erreichen. Zum Beispiel kann das Ziel-Gen kann in einen RNAi Vektor transformiert werden und dann entweder dauerhaft oder transient in Zelllinien oder primäre Zellen nach Gens Knockdown Effekte zu erzielen transformiert, alternativ synthetisierte doppelsträngige Oligonukleotide aus spezifischer Zielgene (RNAi Oligos) kann transient sein transformiert, in Zelllinien oder primäre Zellen nach Zielgene Schweigen; oder synthetisierten Doppelstrang-RNA-Moleküle können in einen Organismus mikroinjiziert werden. Seit dem Fadenwurm C. elegans verwendet Bakterien als Nahrungsquelle, die Fütterung der Tiere mit Bakterien, die doppelsträngige RNA gegen Zielgene bietet eine tragfähige Strategie 6. Hier präsentieren wir eine RNAi FütterungMethode punkten Körpergröße Phänotyp. Körpergröße in C. elegans primär durch die TGF-β reguliert wird - wie Ligand DBL-1, so dass dieser Assay geeignet ist zur Identifizierung von TGF-β Signalkomponenten 7. Wir verwendeten verschiedene Stämme, darunter zwei RNAi überempfindlich Stämme, die RNAi Fütterungsversuche wiederholen. Unsere Ergebnisse zeigten, dass rrf-3-Stamm gab uns die besten erwarteten RNAi Phänotyp. Die Methode ist einfach durchzuführen, reproduzierbar und leicht zu quantifizieren. Darüber hinaus minimiert unser Protokoll die Verwendung von Spezialgeräten, so ist es für kleinere Laboratorien oder jenen an überwiegend Bachelor-Institutionen.

In unserer Forschung konzentrieren wir uns auf die Körpergröße der Regulierung durch die DBL-1/TGF-β Weg. Der Verlust der Funktion der DBL-1-Weg führt zu geringe Körpergröße, einschließlich einer kürzeren Körper Länge im Vergleich mit Wildtyp-Tieren 7,10,11. So Bildschirme für C. elegans Körpergröße Mutanten, imstande sind, TGF-β-Signalisierung Komponenten und Modifikatoren. DBL-1-Signalisierung wird durch eine konservierte TGF-β Signalübertragungswegs, die Zelloberflächen-Rezepto...

Watch this Scientific Journal Video about Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans at JoVE.com

Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans

Wir zeigen, wie die RNAi Fütterung Technik nutzen, um knock down Zielgene und Gäste Körpergröße Phänotyp<em&gt; C. elegans</em&gt;. Dieses Verfahren könnte für eine großtechnische Bildschirm verwendet werden, um potenzielle genetische Komponenten von Interesse, wie sie beispielsweise in der Körpergröße Regulierung durch DBL-1/TGF-β Signalgebung beteiligt sind.

Mit RNA-Interferenz Feeding Strategy to Screen for Genes in Body Größe der Rechtsetzung in der Nematode Beteiligte<em&gt; C. elegans</em

Double-strand RNA-mediated interference (RNAi) is an effective strategy to knock down target gene expression1-3. It has been applied to many model systems ...

using-rna-mediated-interference-feeding-strategy-to-screen-for-genes

Research

JoVE Journal

Biology

Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans

12.2K Aufrufe.  Borough of Manhattan Community College, City Universtiy of New York (CUNY). Wir zeigen, wie die RNAi Fütterung Technik nutzen, um knock down Zielgene und Gäste Körpergröße Phänotyp C. elegans. Dieses Verfahren könnte für eine großtechnische Bildschirm verwendet werden, um potenzielle genetische Komponenten von Interesse, wie sie beispielsweise in der Körpergröße Regulierung durch DBL-1/TGF-β Signalgebung beteiligt sind.

Serie: Using RNA-mediated Interference Feeding Strategy to Screen for Genes Involved in Body Size Regulation in the Nematode C. elegans

Application of a C. elegans Dopamine Neuron Degeneration Assay for the Validation of Potential Parkinson's Disease Genes

Improvements to the diagnosis and treatment of Parkinson's disease (PD) are dependent upon knowledge about susceptibility factors that render populations at risk. In the process of attempting to identify novel genetic factors associated with PD, scientists have generated many lists of candidate genes, polymorphisms, and proteins that represent important advances, but these leads remain mechanistically undefined. Our work is aimed toward significantly narrowing such lists by exploiting the advantages of a simple animal model system. While humans have billions of neurons, the microscopic roundworm Caenorhabditis elegans has precisely 302, of which only eight produce dopamine (DA) in hemaphrodites. Expression of a human gene encoding the PD-associated protein, alpha-synuclein, in C. elegans DA neurons results in dosage and age-dependent neurodegeneration.
Worms expressing human alpha-synuclein in DA neurons are isogenic and express both GFP and human alpha-synuclein under the DA transporter promoter (Pdat-1). The presence of GFP serves as a readily visualized marker for following DA neurodegeneration in these animals. We initially demonstrated that alpha-synuclein-induced DA neurodegeneration could be rescued in these animals by torsinA, a protein with molecular chaperone activity 1. Further, candidate PD-related genes identified in our lab via large-scale RNAi screening efforts using an alpha-synuclein misfolding assay were then over-expressed in C. elegans DA neurons. We determined that five of seven genes tested represented significant candidate modulators of PD as they rescued alpha-synuclein-induced DA neurodegeneration 2. Additionally, the Lindquist Lab (this issue of JoVE) has performed yeast screens whereby alpha-synuclein-dependent toxicity is used as a readout for genes that can enhance or suppress cytotoxicity. We subsequently examined the yeast candidate genes in our C. elegans alpha-synuclein-induced neurodegeneration assay and successfully validated many of these targets 3, 4.
Our methodology involves generation of a C. elegans DA neuron-specific expression vector using recombinational cloning of candidate gene cDNAs under control of the Pdat-1 promoter. These plasmids are then microinjected in wild-type (N2) worms, along with a selectable marker for successful transformation. Multiple stable transgenic lines producing the candidate protein in DA neurons are obtained and then independently crossed into the alpha-synuclein degenerative strain and assessed for neurodegeneration, at both the animal and individual neuron level, over the course of aging.

Application of a C. elegans Dopamine Neuron Degeneration Assay for the Validation of Potential Parkinson&#039;s Disease Genes

This video demonstrates how to use C. elegans to assess dopaminergic neuron neurodegeneration as a model for Parkinson's disease. Furthermore, genetic screens are used to identify factors that either enhance degeneration or are neuroprotective.

Die Anwendung eines C. elegans Dopamin Neuron Degeneration Assay für die Validierung von potenziellen Parkinson Genes

Improvements to the diagnosis and treatment of Parkinson's disease (PD) are dependent upon knowledge about susceptibility factors that render populations ...

Forschung

Biologie

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the messagefor review see 1. However, it's now widely accepted that synonymous codon usage is the primary cause of non-uniform translational elongation rates1. Synonymous codons are not used with identical frequency. A bias exists in the use of synonymous codons with some codons used more frequently than others2. Codon bias is organism as well as tissue specific2,3. Moreover, frequency of codon usage is directly proportional to the concentrations of cognate tRNAs4. Thus, a frequently used codon will have higher multitude of corresponding tRNAs, which further implies that a frequent codon will be translated faster than an infrequent one. Thus, regions on mRNA enriched in rare codons (potential pause sites) will as a rule slow down ribosome movement on the message and cause accumulation of nascent peptides of the respective sizes5-8. These pause sites can have functional impact on the protein expression, mRNA stability and protein foldingfor review see 9. Indeed, it was shown that alleviation of such pause sites can alter ribosome movement on mRNA and subsequently may affect the efficiency of co-translational (in vivo) protein folding1,7,10,11. To understand the process of protein folding in vivo, in the cell, that is ultimately coupled to the process of protein synthesis it is essential to gain comprehensive insights into the impact of codon usage/tRNA content on the movement of ribosomes along mRNA during translational elongation.
Here we describe a simple technique that can be used to locate major translation pause sites for a given mRNA translated in various cell-free systems6-8. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA. The rationale is that at low-frequency codons, the increase in the residence time of the ribosomes results in increased amounts of nascent peptides of the corresponding sizes. In vitro transcribed mRNA is used for in vitro translational reactions in the presence of radioactively labeled amino acids to allow the detection of the nascent chains. In order to isolate ribosome bound nascent polypeptide complexes the translation reaction is layered on top of 30% glycerol solution followed by centrifugation. Nascent polypeptides in polysomal pellet are further treated with ribonuclease A and resolved by SDS PAGE. This technique can be potentially used for any protein and allows analysis of ribosome movement along mRNA and the detection of the major pause sites. Additionally, this protocol can be adapted to study factors and conditions that can alter ribosome movement and thus potentially can also alter the function/conformation of the protein.

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

A technique to identify translational pause sites on mRNA is described. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA, followed by the size analysis of the nascent chains using a denaturing gel electrophoresis.

Isolierung von Ribosom gebunden Nascent Polypeptide<em&gt; In-vitro-</em&gt; Identifizieren Translational Pause Standorten entlang mRNA

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the ...

Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway that polypeptide chain follows during co-translational folding to achieve its functional form is still an enigma. In order to understand this process and to determine the exact conformation of the co-translational folding intermediates, it is essential to develop techniques that allow the isolation of RNCs carrying nascent chains of predetermined sizes to allow their further structural analysis.
SecM (secretion monitor) is a 170 amino acid E. coli protein that regulates expression of the downstream SecA (secretion driving) ATPase in the secM-secA operon6. Nakatogawa and Ito originally found that a 17 amino acid long sequence (150-FSTPVWISQAQGIRAGP-166) in the C-terminal region of the SecM protein is sufficient and necessary to cause stalling of SecM elongation at Gly165, thereby producing peptidyl-glycyl-tRNA stably bound to the ribosomal P-site7-9. More importantly, it was found that this 17 amino acid long sequence can be fused to the C-terminus of virtually any full-length and/or truncated protein thus allowing the production of RNCs carrying nascent chains of predetermined sizes7. Thus, when fused or inserted into the target protein, SecM stalling sequence produces arrest of the polypeptide chain elongation and generates stable RNCs both in vivo in E. coli cells and in vitro in a cell-free system. Sucrose gradient centrifugation is further utilized to isolate RNCs.
The isolated RNCs can be used to analyze structural and functional features of the co-translational folding intermediates. Recently, this technique has been successfully used to gain insights into the structure of several ribosome bound nascent chains10,11. Here we describe the isolation of bovine Gamma-B Crystallin RNCs fused to SecM and generated in an in vitro translation system.

We describe here a technique that is now routinely used to isolate stably bound ribosome nascent chain complexes (RNCs). This technique takes advantage of the discovery that a 17 amino acid long SecM "arrest sequence" can halt translation elongation in a prokaryotic (E. coli) system, when inserted into (or fused to the C-terminus) of virtually any protein.

Mit SECM Arrest Sequenz als Werkzeug zum Ribosom gebunden Polypeptide isolieren

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway ...

Antibody Staining in C. Elegans Using &quot;Freeze-Cracking&quot;

To stain C. elegans with antibodies, the relatively impermeable cuticle must be bypassed by chemical or mechanical methods. "Freeze-cracking" is one method used to physically pull the cuticle from nematodes by compressing nematodes between two adherent slides, freezing them, and pulling the slides apart. Freeze-cracking provides a simple and rapid way to gain access to the tissues without chemical treatment and can be used with a variety of fixatives. However, it leads to the loss of many of the specimens and the required compression mechanically distorts the sample. Practice is required to maximize recovery of samples with good morphology. Freeze-cracking can be optimized for specific fixation conditions, recovery of samples, or low non-specific staining, but not for all parameters at once. For antibodies that require very hard fixation conditions and tolerate the chemical treatments needed to chemically permeabilize the cuticle, treatment of intact nematodes in solution may be preferred. If the antibody requires a lighter fix or if the optimum fixation conditions are unknown, freeze-cracking provides a very useful way to rapidly assay the antibody and can yield specific subcellular and cellular localization information for the antigen of interest.

Antibody Staining in C. Elegans Using &quot;Freeze-Cracking&quot;

"Freeze-cracking," a method for exposing the inner tissues of the nematode C. elegans to antibodies for protein localization, is demonstrated.

Antikörperfärbung in<em&gt; C. Elegans</em&gt; Mit der &quot;Freeze--Cracking&quot;

To stain C.  elegans with antibodies, the relatively impermeable cuticle must be  bypassed by chemical or mechanical methods.  "Freeze-cracking" is one ...

Large-scale Gene Knockdown in C. elegans Using dsRNA Feeding Libraries to Generate Robust Loss-of-function Phenotypes

RNA interference by feeding worms bacteria expressing dsRNAs has been a useful tool to assess gene function in C. elegans. While this strategy works well when a small number of genes are targeted for knockdown, large scale feeding screens show variable knockdown efficiencies, which limits their utility. We have deconstructed previously published RNAi knockdown protocols and found that the primary source of the reduced knockdown can be attributed to the loss of dsRNA-encoding plasmids from the bacteria fed to the animals. Based on these observations, we have developed a dsRNA feeding protocol that greatly reduces or eliminates plasmid loss to achieve efficient, high throughput knockdown. We demonstrate that this protocol will produce robust, reproducible knock down of C. elegans genes in multiple tissue types, including neurons, and will permit efficient knockdown in large scale screens. This protocol uses a commercially available dsRNA feeding library and describes all steps needed to duplicate the library and perform dsRNA screens. The protocol does not require the use of any sophisticated equipment, and can therefore be performed by any C. elegans lab.

Large-scale Gene Knockdown in C. elegans Using dsRNA Feeding Libraries to Generate Robust Loss-of-function Phenotypes

While dsRNA feeding in C. elegans is a powerful tool to assess gene function, current protocols for large scale feeding screens result in variable knockdown efficiencies. We describe an improved protocol for performing large scale RNAi feeding screens that results in highly efficacious and reproducible knockdown of gene expression.

Groß Gene Knockdown in<em&gt; C. elegans</em&gt; Verwenden dsRNA Fütterung Bibliotheken zu Robust Loss-of-function Phänotypen generieren

RNA interference by feeding worms bacteria expressing dsRNAs has been a useful tool to assess gene function in C. elegans. While this strategy works well ...

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the function and regulation of protein folding was studied in vitro, in isolated tissue culture cells and in unicellular organisms. Recent studies have uncovered links between protein homeostasis (proteostasis), metabolism, development, aging, and temperature-sensing. These findings have led to the development of new tools for monitoring protein folding in the model metazoan organism Caenorhabditis elegans. In our laboratory, we combine behavioral assays, imaging and biochemical approaches using temperature-sensitive or naturally occurring metastable proteins as sensors of the folding environment to monitor protein misfolding. Behavioral assays that are associated with the misfolding of a specific protein provide a simple and powerful readout for protein folding, allowing for the fast screening of genes and conditions that modulate folding. Likewise, such misfolding can be associated with protein mislocalization in the cell. Monitoring protein localization can, therefore, highlight changes in cellular folding capacity occurring in different tissues, at various stages of development and in the face of changing conditions. Finally, using biochemical tools ex vivo, we can directly monitor protein stability and conformation. Thus, by combining behavioral assays, imaging and biochemical techniques, we are able to monitor protein misfolding at the resolution of the organism, the cell, and the protein, respectively.

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

To study the relationship between protein homeostasis, stress and aging, we monitored changes in protein folding by following protein dysfunction, protein localization in the cell and protein stability at the organismal, cellular and protein levels, using the genetically tractable metazoan Caenorhabditis elegans as a model system.

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the ...

Methods to Assess Subcellular Compartments of Muscle in C. elegans

Muscle is a dynamic tissue that responds to changes in nutrition, exercise, and disease state. The loss of muscle mass and function with disease and age are significant public health burdens. We currently understand little about the genetic regulation of muscle health with disease or age. The nematode C. elegans is an established model for understanding the genomic regulation of biological processes of interest. This worm&#8217;s body wall muscles display a large degree of homology with the muscles of higher metazoan species. Since C. elegans is a transparent organism, the localization of GFP to mitochondria and sarcomeres allows visualization of these structures in vivo. Similarly, feeding animals cationic dyes, which accumulate based on the existence of a mitochondrial membrane potential, allows the assessment of mitochondrial function in vivo. These methods, as well as assessment of muscle protein homeostasis, are combined with assessment of whole animal muscle function, in the form of movement assays, to allow correlation of sub-cellular defects with functional measures of muscle performance. Thus, C. elegans provides a powerful platform with which to assess the impact of mutations, gene knockdown, and/or chemical compounds upon muscle structure and function. Lastly, as GFP, cationic dyes, and movement assays are assessed non-invasively, prospective studies of muscle structure and function can be conducted across the whole life course and this at present cannot be easily investigated in vivo in any other organism.

Methods to Assess Subcellular Compartments of Muscle in C. elegans

Skeletal muscle is essential for locomotion and is the bodies&#8217; main protein store. Muscle health measurements within C. elegans are described. Prospective changes to muscle structure and function are assessed using localized GFP and cationic dyes.

Methoden zur subzellulärer Kompartimente der Muskel in Beurteilen<em&gt; C. elegans</em

Muscle is a dynamic tissue that responds to changes in nutrition, exercise, and disease state. The loss of muscle mass and function with disease and age ...

Tracking and Quantifying Developmental Processes in C. elegans Using Open-source Tools

Quantitatively capturing developmental processes is crucial to derive mechanistic models and key to identify and describe mutant phenotypes. Here protocols are presented for preparing embryos and adult C. elegans animals for short- and long-term time-lapse microscopy and methods for tracking and quantification of developmental processes. The methods presented are all based on C. elegans strains available from the Caenorhabditis Genetics Center and on open-source software that can be easily implemented in any laboratory independently of the microscopy system used. A reconstruction of a 3D cell-shape model using the modelling software IMOD, manual tracking of fluorescently-labeled subcellular structures using the multi-purpose image analysis program Endrov, and an analysis of cortical contractile flow using PIVlab (Time-Resolved Digital Particle Image Velocimetry Tool for MATLAB) are shown. It is discussed how these methods can also be deployed to quantitatively capture other developmental processes in different models, e.g., cell tracking and lineage tracing, tracking of vesicle flow.

Tracking and Quantifying Developmental Processes in C. elegans Using Open-source Tools

Here it is shown how to track and quantify developmental processes in C. elegans. The methods presented are based on open-source tools that can be easily implemented. It is demonstrated how to reconstruct 3D cell-shape models, how to manually track subcellular structures, and how to analyze cortical contractile flow.

Tracking und Quantifizierung von Entwicklungsprozessen in<em&gt; C. elegans</em&gt; Verwendung von Open-Source-Werkzeuge

Quantitatively capturing developmental processes is crucial to derive mechanistic models and key to identify and describe mutant phenotypes. Here ...

Measuring RAN Peptide Toxicity in C. elegans

C. elegans is commonly used to model age-related neurodegenerative diseases caused by repeat expansion mutations, such as Amyotrophic Lateral Sclerosis (ALS) and Huntington&#8217;s disease. Recently, repeat expansion-containing RNA was shown to be the substrate for a novel type of protein translation called repeat-associated non-AUG-dependent (RAN) translation. Unlike canonical translation, RAN translation does not require a start codon and only occurs when repeats exceed a threshold length. Because there is no start codon to determine the reading frame, RAN translation occurs in all reading frames from both sense and antisense RNA templates that contain a repeat expansion sequence. Therefore, RAN translation expands the number of possible disease-associated toxic peptides from one to six. Thus far, RAN translation has been documented in eight different repeat expansion-based neurodegenerative and neuromuscular diseases. In each case, deciphering which RAN products are toxic, as well as their mechanisms of toxicity, is a critical step towards understanding how these peptides contribute to disease pathophysiology. In this paper, we present strategies to measure the toxicity of RAN peptides in the model system C. elegans. First, we describe procedures for measuring RAN peptide toxicity on the growth and motility of developing C. elegans. Second, we detail an assay for measuring postdevelopmental, age-dependent effects of RAN peptides on motility. Finally, we describe a neurotoxicity assay for evaluating the effects of RAN peptides on neuron morphology. These assays provide a broad assessment of RAN peptide toxicity and may be useful for performing large-scale genetic or small molecule screens to identify disease mechanisms or therapies.

Measuring RAN Peptide Toxicity in C. elegans

Repeat-associated non-ATG-dependent translational products are emerging pathogenic features of several repeat expansion-based diseases. The goal of the protocol described is to evaluate toxicity caused by these peptides using behavioral and cellular assays in the model system C. elegans.

Messung der RAN-Peptidtoxizität in C. elegans

C. elegans is commonly used to model age-related neurodegenerative diseases caused by repeat expansion mutations, such as Amyotrophic Lateral Sclerosis ...

Using Caenorhabditis elegans to Screen for Tissue-Specific Chaperone Interactions

Correct folding and assembly of proteins and protein complexes are essential for cellular function. Cells employ quality control pathways that correct, sequester or eliminate damaged proteins to maintain a healthy proteome, thus ensuring cellular proteostasis and preventing further protein damage. Because of redundant functions within the proteostasis network, screening for detectable phenotypes using knockdown or mutations in chaperone-encoding genes in the multicellular organism Caenorhabditis elegans results in the detection of minor or no phenotypes in most cases. We have developed a targeted screening strategy to identify chaperones required for a specific function and thus bridge the gap between phenotype and function. Specifically, we monitor novel chaperone interactions using RNAi synthetic interaction screens, knocking-down chaperone expression, one chaperone at a time, in animals carrying a mutation in a chaperone-encoding gene or over-expressing a chaperone of interest. By disrupting two chaperones that individually present no gross phenotype, we can identify chaperones that aggravate or expose a specific phenotype when both perturbed. We demonstrate that this approach can identify specific sets of chaperones that function together to modulate the folding of a protein or protein complexes associated with a given phenotype.

Using Caenorhabditis elegans to Screen for Tissue-Specific Chaperone Interactions

To study chaperone-chaperone and chaperone-substrate interactions, we perform synthetic interaction screens in Caenorhabditis elegans using RNA interference in combination with mild mutations or over-expression of chaperones and monitor tissue-specific protein dysfunction at the organismal level.

Verwendung von Caenorhabditis elegans zum Screening auf gewebespezifische Chaperon-Interaktionen

Correct folding and assembly of proteins and protein complexes are essential for cellular function. Cells employ quality control pathways that correct, ...