Diese Arbeit wurde von der Abteilung für Interne Forschung des National Institute for Allergy and Infectious Diseases, National Institutes of Health unterstützt. Wir danken Johannes Huppa und Mark Davis, der uns mit dem scFv von H57 in diesen Studien verwendet. RV möchte Keir Neumann für hilfreiche Diskussionen bedanken bei der Entwicklung dieser Technik.

<ol>
	<li>Call, M. E., Wucherpfennig, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+T+cell+receptor:+critical+role+of+the+membrane+environment+in+receptor+assembly+and+function.">The T cell receptor: critical role of the membrane environment in receptor assembly and function.</a> Annu. Rev. Immunol. 23, 101-125 (2005).</li><li>Smith-Garvin, J. E., Koretzky, G. A., Jordan, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=S.T+cell+activation.">S.T cell activation.</a> Annu. Rev. Immunol. 27, 591-619 (2009).</li><li>Bezbradica, J. 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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T+cell+receptor-proximal+signals+are+sustained+in+peripheral+microclusters+and+terminated+in+the+central+supramolecular+activation+cluster.">T cell receptor-proximal signals are sustained in peripheral microclusters and terminated in the central supramolecular activation cluster.</a> Immunity. 25, 117-127 (2006).</li><li>Yokosuka, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Newly+generated+T+cell+receptor+microclusters+initiate+and+sustain+T+cell+activation+by+recruitment+of+Zap70+and+SLP-76.">Newly generated T cell receptor microclusters initiate and sustain T cell activation by recruitment of Zap70 and SLP-76.</a> Nat. Immunol. 6, 1253-1262 (2005).</li><li>Huppa, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TCR-peptide-MHC+interactions+in+situ+show+accelerated+kinetics+and+increased+affinity.">TCR-peptide-MHC interactions in situ show accelerated kinetics and increased affinity.</a> Nature. 463, 963-967 (2010).</li><li>Tolar, P., Pierce, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+conformation-induced+oligomerization+model+for+B+cell+receptor+microclustering+and+signaling.">A conformation-induced oligomerization model for B cell receptor microclustering and signaling.</a> Curr. Top. Microbiol. Immunol. 340, 155-169 (2010).</li><li>Treanor, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+membrane+skeleton+controls+diffusion+dynamics+and+signaling+through+the+B+cell+receptor.">The membrane skeleton controls diffusion dynamics and signaling through the B cell receptor.</a> Immunity. 32, 187-199 (2010).</li><li>Treanor, B., Batista, F. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanistic+insight+into+lymphocyte+activation+through+quantitative+imaging+and+theoretical+modelling.">Mechanistic insight into lymphocyte activation through quantitative imaging and theoretical modelling.</a> Curr. Opin. Immunol. 19, 476-483 (2007).</li><li>Sylvain, N. R., Nguyen, K., Bunnell, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vav1-mediated+scaffolding+interactions+stabilize+SLP-76+microclusters+and+contribute+to+antigen-dependent+T+cell+responses.">Vav1-mediated scaffolding interactions stabilize SLP-76 microclusters and contribute to antigen-dependent T cell responses.</a> Sci. Signal. 4, ra14-ra14 (2011).</li><li>Purbhoo, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+of+subsynaptic+vesicles+and+surface+microclusters+at+the+immunological+synapse.">Dynamics of subsynaptic vesicles and surface microclusters at the immunological synapse.</a> Sci. Signal. 3, ra36-ra36 (2010).</li><li>Lasserre, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ezrin+tunes+T-cell+activation+by+controlling+Dlg1+and+microtubule+positioning+at+the+immunological+synapse.">Ezrin tunes T-cell activation by controlling Dlg1 and microtubule positioning at the immunological synapse.</a> EMBO. J. 29, 2301-2314 (2010).</li><li>Balagopalan, L., Sherman, E., Barr, V. A., Samelson, L. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+techniques+for+assaying+lymphocyte+activation+in+action.">Imaging techniques for assaying lymphocyte activation in action.</a> Nat. Rev. Immunol. 11, 21-33 (2011).</li><li>Axelrod, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+7:+Total+internal+reflection+fluorescence+microscopy.">Chapter 7: Total internal reflection fluorescence microscopy.</a> Methods Cell. Biol. 89, 169-221 (2008).</li><li>Williamson, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pre-existing+clusters+of+the+adaptor+Lat+do+not+participate+in+early+T+cell+signaling+events.">Pre-existing clusters of the adaptor Lat do not participate in early T cell signaling events.</a> Nat. Immunol. 12, 655-662 (2011).</li></ol>

Alle Tiere in diesen Experimenten verwendet wurden in einem spezifischen Pathogen-freien Umgebung gehalten, und die Experimente wurden von den National Institutes of Health Animal Care und Use Committee gebilligt.

Wir beschreiben hier ein System zu studieren Signalisierung in Antigen-spezifischen T-Zellen, primäre Maustaste mit TIRFM und Glas unterstützten Lipiddoppelschichten als künstliche APCs. Die Technik beruht auf erfolgreich exprimieren GFP-markierten Proteine ​​in diesen Zellen. Transfektion von T-Zellen ist immer eine anspruchsvolle Aufgabe. Typischerweise werden Elektroporation oder Gentransfer mit Retroviren oder Lentiviren verwendet. Eine Technik ist nicht überlegen über das andere, beide haben ihre Grenzen und Vorteile. Wir finden, dass die Elektroporation hat folgende Vorteile: 1) Es ist nicht erforderlich, dass die Zellen aktiv werden Unterteilen wie Retroviren, aber nicht Lentiviren erforderlich ist, und 2) Die Expression kann durch Variieren der Zeit wurden die Zellen vor der Bebilderung inkubiert werden, gesteuert werden. Der größte Nachteil ist, dass wir es sehr schwierig, Proteine, die große Abmessungen in primären Zellen auszudrücken. Wir haben eine Methode, die uns sehr gut die Lebensfähigkeit der Zellen nach der Elektroporation vorgestellt. Als ein Ergebnis ist es geltenden Gesundheitsschutzmaßnahmenle zu benutzen, um siRNA-vermittelten Gen-Silencing zu erreichen. Wir beschreiben hier eine maßgeschneiderte Zwei-Kanal gleichzeitige Erfassung TIRF Mikroskop, das chromatisch korrigiert wird, und erfordert keine separate Ausrichtung für verschiedene Wellenlängen. Diese Funktionen, jedoch sind im Handel erhältlich. Unser System basiert auf den Prinzipien der TIRF-Mikroskopie veröffentlicht von Experten auf diesem Gebiet und ist billiger als kommerzielle Alternativen basieren. Eine mögliche Kritik an unserem Design ist, dass wir mit dem gleichen Einfallswinkel für die verschiedenen Anregungswellenlängen. Dies würde in einer anderen TIRF Eindringtiefe für verschiedene Anregungswellenlängen führen. Wir glauben, dass diese Effekte gering sind, da die evaneszente Welle ist eine exponentiell abklingende Feld und die Tiefe der TIRF Feld ist eine lineare Funktion der Wellenlänge. Fluorophore nahe der Glasoberfläche erleben keinen Unterschied in der Intensitäten zwischen den beiden Wellenlängen. Für Fluorophore in der Nähe des PEnetration Tiefe wird die Intensitätsunterscheidung 1,3-fachen für die beiden Wellenlängen 488 und 640 nm und 1,15-fachen für die beiden Wellenlängen 488 und 561 nm sein. Das gleiche System kann in Verbindung mit Super-Resolution-Techniken, die Verwendung von TIRF-Beleuchtung machen eingesetzt werden. Wir haben auch ein zwei Kamera-System, das speziell angefertigten ist beschrieben. Wie die TIRF-System, sind ähnliche Apparate auch kommerziell erhältlich. Unser System bietet Flexibilität, um die Filter und dichroics zu ändern, was ihre Anwendung bei verschiedenen Kombinationen von Wellenlängen. Der Nachteil des eigenen Systems ist der Grad der Drehung um die beiden Bilder auszurichten. Dieses Problem kann durch die Verwendung Kamera steht, die Piezo angetrieben werden und bieten rotatorischen Ausrichtung gelöst werden. Wir haben auch erfolgreich ein Zwei-Kamera-System auf diesem Mikroskop durchgeführt, in dem die Kameras verschieden sind und unterschiedliche Punktgrößen. Ein solches System wäre nützlich, wenn man brauchte Empfindlichkeit in einen Kanal und einen großen dyDynamikbereich in einem anderen, sind die beide nur selten in der gleichen Kamera zur Verfügung. Wir nutzten die Photometrics HQ-2-Kamera bei 2x2 Binning gibt uns eine effektive Pixelgröße von 12,9 um mit dem Photometrics Quant-EM-Kamera, die eine Pixelgröße von 16 mu m aufweist. Ein 180 mm Brennweite Tubuslinse wurde für die Quant-EM eingesetzt und ein 145 mm Brennweite Tubuslinse wurde für die HQ-2-Kamera verwendet. Der HQ-2 wurde unter Verwendung Metamorph-Software und die Quant-EM wurde über Mikro-Manager-Software auf einem separaten Computer in externe Trigger-Modus gesteuert. Der externe Trigger wurde der Quant-EM-Kamera mit einem digitalen Ausgang des DAC Messung Computing Platine, die als zusätzliche Blende in der configure Beleuchtungseinstellungen Metamorph umgesetzt wurde bereitgestellt. Das Verhältnis der Brennweiten der Tubuslinsen entspricht dem Verhältnis der effektiven Pixelgrößen. Eine repräsentative Ausrichtung in 5 gezeigt.

<table border="1"><tbody><tr><td> Name des Reagenzes </td><td> Firma </td><td> Katalog-Nummer </td><td> Kommentare </td></tr><tr><td> Amaxa Nucleofector Kit für Maus-T-Zellen </td><td> Lonza Inc. </td><td> VPA-1006 </td><td></td></tr><tr><td> PureLink HiPure Plasmid Midiprep Kit </td><td> Life Technologies </td><td> K2100-05 </td><td> Für Endotoxin freie DNA PREPS </td></tr><tr><td> Amaxa Nucleofector- </td><td> Lonza Inc. </td><td> AAD-1001 </td><td></td></tr><tr><td> Rekombinantes Mäuse-IL-2 </td><td> Peprotech Inc. </td><td> 212-12 </td><td></td></tr><tr><td> Fluoresbrite Multifluorescent Microspheres 0.20μm </td><td> Polysciences, Inc. </td><td> 24050-5 </td><td></td></tr><tr><td> Lab-Tek II 8-Well-Kammer-Deckglas </td><td> Thermo Scientific, Nunc </td><td> 155409 </td><td></td></tr></tbody></table>

a tirf microscopy technique for real-time, simultaneous imaging of the tcr and its associated signaling proteins

Diese Signalisierung wird durch den T-Zell-Rezeptor (TCR) ausgelöst wird, wenn es durch antigene Peptidfragmente von Haupthistokompatibilitätskomplex (pMHC) Proteine ​​auf der Oberfläche von Antigen präsentierenden Zellen (APC) gebunden zu eingreift. Der TCR-Komplex der Ligandenbindung TCRαβ Heterodimer besteht, das nicht-kovalent assoziierten mit CD3-Dimere (die εδ und εγ Heterodimere und die ζζ Homodimer) 1. Beim Eingriff des Rezeptors, werden die CD3 ζ-Ketten der Src-Familie-Kinase phosphoryliert, Lck. Dies führt zur Rekrutierung der Syk-Familie-Kinase, ZAP70, der dann phosphoryliert wird und durch Lck aktiviert. Danach phosphoryliert ZAP70 den Adapter Proteine ​​LAT und SLP76, initiiert die Bildung des proximalen Signalkomplex, die eine große Anzahl verschiedener Signalmoleküle 2. Die Bildung dieses Komplexes führt schließlich zu Kalzium-und Ras-abhängige transcription Faktor Aktivierung und die daraus folgende Einleitung einer komplexen Reihe von Genexpression, die Anlass zu T-Zell-Differenzierung 2. TCR-Signale (und die daraus resultierende Zustand der Differenzierung) moduliert werden von vielen anderen Faktoren ab, einschließlich Antigen Potenz und Übersprechen mit co-stimulatory/co-inhibitory, Chemokin-und Zytokin-Rezeptoren 3-4. Die Untersuchung der räumlichen und zeitlichen Organisation des proximalen Signalkomplex unter verschiedenen Bedingungen Stimulation ist somit Schlüssel zum Verständnis der TCR-Signalwegs sowie deren Regulation durch andere Signalwege. Ein sehr nützliches Modell zu untersuchenden System Signalisierung von der TCR an der Plasmamembran in T-Zellen initiiert ist Glas-Lipiddoppelschichten, wie zuvor beschrieben 5-6. Sie können verwendet werden, um antigene pMHC Komplexen, Adhäsion und co-stimulatorische Moleküle an T-Zellen-APC, die als künstliche präsentieren. Durch die Abbildung die T-Zellen der Interaktion mit demLipid-Doppelschicht mit innerer Totalreflexion (TIRFM), können wir die Erregung zu beschränken innerhalb von 100 nm von dem Raum zwischen dem Glas und der Zelloberfläche 7-8. Dies erlaubt uns, in erster Linie die Bild Signalisierung Ereignisse an der Plasmamembran. Wie wir in der Abbildung der Einstellung von Signalproteinen an den TCR-Komplex interessiert sind, beschreiben wir ein Zwei-Kamera-TIRF Abbildungssystem, wobei das TCR, mit fluoreszierenden markierten Fab (Fragment antigen-binding) Fragmente des H57-Antikörper (aufgereinigt aus Hybridom H57-597 , ATCC, ATCC Nummer: kann HB-218), die spezifisch für TCRβ ist, und Signalproteine, markiert mit GFP, gleichzeitig und in Echtzeit abgebildet werden. Diese Strategie ist notwendig aufgrund der hohen Dynamik sowohl der T-Zellen und der Signalwege, die an der TCR auftreten werden. Diese bildgebenden Verfahren hat die Forscher einzelne Bild 9-11 Liganden sowie Rekrutierung von Signalmolekülen an aktivierten Rezeptoren und erlaubtist ein ausgezeichnetes System für Biochemie in-situ 12-16 studieren.

Watch this Scientific Journal Video about A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins at JoVE.com

A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins

Die Aufspaltung der Proteine ​​entweder innerhalb der Plasmamembran oder in intrazellulären Orten eines Regulierungsmechanismus, stark beeinflussen können Signalisierung Ergebnisse, daher zu verstehen Signalisierung ist es wichtig, die räumliche und zeitliche Verhalten der beteiligten Proteine ​​zu untersuchen. Wir beschreiben hier eine TIRF-Mikroskopie basierendes System zur Signaltransduktion in T-Zellen zu studieren, aber ist breit anwendbar.

Ein TIRF Mikroskopie-Technik für Echtzeit-, Einzigartige Bilder aus dem TCR und der damit verbundenen Signalproteine

Signaling is initiated through the T Cell Receptor (TCR) when it is engaged by antigenic peptide fragments bound by Major Histocompatibility Complex ...

a-tirf-microscopy-technique-for-real-time-simultaneous-imaging-tcr

Research

JoVE Journal

Immunology and Infection

23.7K Aufrufe.  National Institute of Allergy and Infectious Diseases, National Institutes of Health. Die Aufspaltung der Proteine ​​entweder innerhalb der Plasmamembran oder in intrazellulären Orten eines Regulierungsmechanismus, stark beeinflussen können Signalisierung Ergebnisse, daher zu verstehen Signalisierung ist es wichtig, die räumliche und zeitliche Verhalten der beteiligten Proteine ​​zu untersuchen. Wir beschreiben hier eine TIRF-Mikroskopie basierendes System zur Signaltransduktion in T-Zellen zu studieren, aber ist breit anwendbar.

Serie: A TIRF Microscopy Technique for Real-time, Simultaneous Imaging of the TCR and its Associated Signaling Proteins

Real-time Imaging of Leukotriene B4 Mediated Cell Migration and BLT1 Interactions with &beta;-arrestin

G-protein coupled receptors (GPCRs) belong to the seven transmembrane protein family and mediate the transduction of extracellular signals to intracellular responses. GPCRs control diverse biological functions such as chemotaxis, intracellular calcium release, gene regulation in a ligand dependent manner via heterotrimeric G-proteins1-2. Ligand binding induces a series of conformational changes leading to activation of heterotrimeric G-proteins that modulate levels of second messengers such as cyclic adenosine monophosphate (cAMP), inositol triphosphate (IP3) and diacyl glycerol (DG). Concomitant with activation of the receptor ligand binding also initiates a series of events to attenuate the receptor signaling via desensitization, sequestration and/or internalization. The desensitization process of GPCRs occurs via receptor phosphorylation by G-protein receptor kinases (GRKs) and subsequent binding of &beta;-arrestins3. &beta;-arrestins are cytosolic proteins and translocate to membrane upon GPCR activation, binding to phosphorylated receptors (most cases) there by facilitating receptor internalization 4-6.
Leukotriene B4 (LTB4) is a pro-inflammatory lipid molecule derived from arachidonic acid pathway and mediates its actions via GPCRs, LTB4 receptor 1 (BLT1; a high affinity receptor) and LTB4 receptor 2 (BLT2; a low affinity receptor)7-9. The LTB4-BLT1 pathway has been shown to be critical in several inflammatory diseases including, asthma, arthritis and atherosclerosis10-17. The current paper describes the methodologies developed to monitor LTB4-induced leukocyte migration and the interactions of BLT1 with &beta;-arrestin and , receptor translocation in live cells using microscopy imaging techniques18-19.
Bone marrow derived dendritic cells from C57BL/6 mice were isolated and cultured as previously described 20-21. These cells were tested in live cell imaging methods to demonstrate LTB4 induced cell migration. The human BLT1 was tagged with red fluorescent protein (BLT1-RFP) at C-terminus and &beta;-arrestin1 tagged with green fluorescent protein (&beta;-arr-GFP) and transfected the both plasmids into Rat Basophilic Leukomia (RBL-2H3) cell lines18-19. The kinetics of interaction between these proteins and localization were monitored using live cell video microscopy. The methodologies in the current paper describe the use of microscopic techniques to investigate the functional responses of G-protein coupled receptors in live cells. The current paper also describes the use of Metamorph software to quantify the fluorescence intensities to determine the kinetics of receptor and cytosolic protein interactions.

Real-time Imaging of Leukotriene B4 Mediated Cell Migration and BLT1 Interactions with &amp;#946;-arrestin

This paper describes the methodology to determine the chemotactic response of leukocytes to specific ligands and identify interactions between the cell surface receptors and cytosolic proteins using live cell imaging techniques.

Real-time Imaging von Leukotrien B 4 Vermittelte Zellmigration und BLT1 Wechselwirkungen mit β-Arrestin

G-protein coupled receptors (GPCRs) belong to the seven transmembrane protein family and mediate the transduction of extracellular signals to ...

Forschung

Immunologie und Infektion

Real-time Live Imaging of T-cell Signaling Complex Formation

Protection against infectious diseases is mediated by the immune system 1,2. T lymphocytes are the master coordinators of the immune system, regulating the activation and responses of multiple immune cells 3,4. T-cell activation is dependent on the recognition of specific antigens displayed by antigen presenting cells (APCs). The T-cell antigen receptor (TCR) is specific to each T-cell clone and determines antigen specificity 5. The binding of the TCR to the antigen induces the phosphorylation of components of the TCR complex. In order to promote T-cell activation, this signal must be transduced from the membrane to the cytoplasm and the nucleus, initiating various crucial responses such as recruitment of signaling proteins to the TCR;APC site (the immune synapse), their molecular activation, cytoskeletal rearrangement, elevation of intracellular calcium concentration, and changes in gene expression 6,7. The correct initiation and termination of activating signals is crucial for appropriate T-cell responses. The activity of signaling proteins is dependent on the formation and termination of protein-protein interactions, post translational modifications such as protein phosphorylation, formation of protein complexes, protein ubiquitylation and the recruitment of proteins to various cellular sites 8. Understanding the inner workings of the T-cell activation process is crucial for both immunological research and clinical applications.
Various assays have been developed in order to investigate protein-protein interactions; however, biochemical assays, such as the widely used co-immunoprecipitation method, do not allow protein location to be discerned, thus precluding the observation of valuable insights into the dynamics of cellular mechanisms. Additionally, these bulk assays usually combine proteins from many different cells that might be at different stages of the investigated cellular process. This can have a detrimental effect on temporal resolution. The use of real-time imaging of live cells allows both the spatial tracking of proteins and the ability to temporally distinguish between signaling events, thus shedding light on the dynamics of the process 9,10. We present a method of real-time imaging of signaling-complex formation during T-cell activation. Primary T-cells or T-cell lines, such as Jurkat, are transfected with plasmids encoding for proteins of interest fused to monomeric fluorescent proteins, preventing non-physiological oligomerization 11. Live T cells are dropped over a coverslip pre-coated with T-cell activating antibody 8,9, which binds to the CD3/TCR complex, inducing T-cell activation while overcoming the need for specific activating antigens. Activated cells are constantly imaged with the use of confocal microscopy. Imaging data are analyzed to yield quantitative results, such as the colocalization coefficient of the signaling proteins.

We describe a live-cell imaging method that provides insight into protein dynamics during the T-cell activation process. We demonstrate the combined usage of the T-cell spreading assay, confocal microscopy and imaging analysis to yield quantitative results to follow signaling complex formation throughout T-cell activation.

Echtzeit-Live-Imaging von T-Zell-Signaling Complex Formation

Protection against infectious diseases is mediated by the immune system 1,2. T lymphocytes are the master coordinators of the immune system, regulating ...

Real-time Imaging of Endothelial Cell-cell Junctions During Neutrophil Transmigration Under Physiological Flow

During inflammation, leukocytes leave the circulation and cross the endothelium to fight invading pathogens in underlying tissues. This process is known as leukocyte transendothelial migration. Two routes for leukocytes to cross the endothelial monolayer have been described: the paracellular route, i.e., through the cell-cell junctions and the transcellular route, i.e., through the endothelial cell body. However, it has been technically difficult to discriminate between the para- and transcellular route. We developed a simple in vitro assay to study the distribution of endogenous VE-cadherin and PECAM-1 during neutrophil transendothelial migration under physiological flow conditions. Prior to neutrophil perfusion, endothelial cells were briefly treated with fluorescently-labeled antibodies against VE-cadherin and PECAM-1. These antibodies did not interfere with the function of both proteins, as was determined by electrical cell-substrate impedance sensing and FRAP measurements. Using this assay, we were able to follow the distribution of endogenous VE-cadherin and PECAM-1 during transendothelial migration under flow conditions and discriminate between the para- and transcellular migration routes of the leukocytes across the endothelium.

Leukocytes cross the endothelial monolayer using the paracellular or the transcellular route. We developed a simple assay to follow the distribution of endogenous junctional VE-cadherin and PECAM-1 during leukocyte transendothelial migration under physiological flow to discriminate between the two transmigration routes.

Echtzeit-Bildgebung von Zell-Zell-Endothelial Junctions Während Neutrophile Transmigration unter physiologischen Fluss

During inflammation, leukocytes leave the circulation and cross the endothelium to fight invading pathogens in underlying tissues. This process is known ...

Real-time Imaging of Myeloid Cells Dynamics in ApcMin/+ Intestinal Tumors by Spinning Disk Confocal Microscopy

Myeloid cells are the most abundant immune cells within tumors and have been shown to promote tumor progression. Modern intravital imaging techniques enable the observation of live cellular behavior inside the organ but can be challenging in some types of cancer due to organ and tumor accessibility such as intestine. Direct observation of intestinal tumors has not been previously reported. A surgical procedure described here allows direct observation of myeloid cell dynamics within the intestinal tumors in live mice by using transgenic fluorescent reporter mice and injectable tracers or antibodies. For this purpose, a four-color, multi-region, micro-lensed spinning disk confocal microscope that allows long-term continuous imaging with rapid image acquisition has been used. ApcMin/+ mice that develop multiple adenomas in the small intestine are crossed with c-fms-EGFP mice to visualize myeloid cells and with ACTB-ECFP mice to visualize intestinal epithelial cells of the crypts. Procedures for labeling different tumor components, such as blood vessels and neutrophils, and the procedure for positioning the tumor for imaging through the serosal surface are also described. Time-lapse movies compiled from several hours of imaging allow the analysis of myeloid cell behavior in situ in the intestinal microenvironment.

Real-time Imaging of Myeloid Cells Dynamics in ApcMin/+ Intestinal Tumors by Spinning Disk Confocal Microscopy

By using transgenic reporter mice and injectable fluorescent labels, long-term intravital spinning disk confocal microscopy enables direct visualization of myeloid cell behavior into intestinal adenoma in the ApcMin/+ colorectal cancer model.

Echtzeit-Imaging von myeloischen Zellen in Dynamics<em&gt; Apc<sup&gt; Min / +</sup</em&gt; Darmtumoren durch Spinning-Disk-konfokale Mikroskopie

Myeloid cells are the most abundant immune cells within tumors and have been shown to promote tumor progression. Modern intravital imaging techniques ...

Simultaneous Quantification of T-Cell Receptor Excision Circles (TRECs) and K-Deleting Recombination Excision Circles (KRECs) by Real-time PCR

T-cell receptor excision circles (TRECs) and K-deleting recombination excision circles (KRECs) are circularized DNA elements formed during recombination process that creates T- and B-cell receptors. Because TRECs and KRECs are unable to replicate, they are diluted after each cell division, and therefore persist in the cell. Their quantity in peripheral blood can be considered as an estimation of thymic and bone marrow output. By combining well established and commonly used TREC assay with a modified version of KREC assay, we have developed a duplex quantitative real-time PCR that allows quantification of both newly-produced T and B lymphocytes in a single assay. The number of TRECs and KRECs are obtained using a standard curve prepared by serially diluting TREC and KREC signal joints cloned in a bacterial plasmid, together with a fragment of T-cell receptor alpha constant gene that serves as reference gene. Results are reported as number of TRECs and KRECs/106 cells or per ml of blood. The quantification of these DNA fragments have been proven useful for monitoring immune reconstitution following bone marrow transplantation in both children and adults, for improved characterization of immune deficiencies, or for better understanding of certain immunomodulating drug activity.

Simultaneous Quantification of T-Cell Receptor Excision Circles TRECs and K-Deleting Recombination Excision Circles KRECs by Real-time PCR

Here, we describe a method for simultaneous quantification of T-cell receptor excision circles (TRECs) and K-deleting recombination excision circles (KRECs). The TREC/KREC assay can be used as marker of thymic and bone marrow output.

Simultane Quantifizierung von T-Zell-Rezeptor-Excision Kreis (TRECs) und K-Löschen Rekombination Excision Kreis (KRECs) durch Echtzeit-PCR

T-cell receptor excision circles (TRECs) and K-deleting recombination excision circles (KRECs) are circularized DNA elements formed during recombination ...

Analysis of Yersinia enterocolitica Effector Translocation into Host Cells Using Beta-lactamase Effector Fusions

Many gram-negative bacteria including pathogenic Yersinia spp. employ type III secretion systems to translocate effector proteins into eukaryotic target cells. Inside the host cell the effector proteins manipulate cellular functions to the benefit of the bacteria. To better understand the control of type III secretion during host cell interaction, sensitive and accurate assays to measure translocation are required. We here describe the application of an assay based on the fusion of a Yersinia enterocolitica effector protein fragment (Yersinia outer protein; YopE) with TEM-1 beta-lactamase for quantitative analysis of translocation. The assay relies on cleavage of a cell permeant FRET dye (CCF4/AM) by translocated beta-lactamase fusion. After cleavage of the cephalosporin core of CCF4 by the beta-lactamase, FRET from coumarin to fluorescein is disrupted and excitation of the coumarin moiety leads to blue fluorescence emission. Different applications of this method have been described in the literature highlighting its versatility. The method allows for analysis of translocation in vitro and also in in vivo, e.g., in a mouse model. Detection of the fluorescence signals can be performed using plate readers, FACS analysis or fluorescence microscopy. In the setup described here, in vitro translocation of effector fusions into HeLa cells by different Yersinia mutants is monitored by laser scanning microscopy. Recording intracellular conversion of the FRET reporter by the beta-lactamase effector fusion in real-time provides robust quantitative results. We here show exemplary data, demonstrating increased translocation by a Y. enterocolitica YopE mutant compared to the wild type strain.

Analysis of Yersinia enterocolitica Effector Translocation into Host Cells Using Beta-lactamase Effector Fusions

Effector translocation into host cells via a type III secretion system is a common virulence strategy among gram-negative bacteria. A beta-lactamase effector fusion based assay for quantitative analysis of translocation was applied. In Yersinia infected cells, conversion of a FRET reporter by the beta-lactamase is monitored using laser scanning microscopy.

Analyse von<em&gt; Yersinia enterocolitica</em&gt; Effektor Translokation in Wirtszellen unter Verwendung Beta-Lactamase-Effektor-Fusionen

Many gram-negative bacteria including pathogenic Yersinia spp. employ type III secretion systems to translocate effector proteins into eukaryotic target ...

Imaging Neutrophils and Monocytes in Mesenteric Veins by Intravital Microscopy on Anaesthetized Mice in Real Time

Efficient immune response is dependent on rapid mobilization of blood leukocytes to the site of infection or injury. Investigating leukocyte migration in vivo is crucial for understanding the molecular basis of leukocyte transendothelial migration and interaction with vascular endothelium. One powerful approach involves intravital microscopy on transgenic mice expressing fluorescent proteins in cells of interest.
Here we present a protocol for imaging monocytes and neutrophils in the CX3CR1gfp/wt mouse i.v. injected with orange dye-labeled neutrophils with an inverted confocal microscope. Time-lapse movies gathered from 30 min&#160;to several hours of imaging allow the analysis of leukocyte behavior in mesenteric veins under both steady state and inflammatory conditions. We also describe the steps to locally induce blood vessel inflammation with TLR2/TLR1 agonist Pam3SK4 and monitor the subsequent recruitment of neutrophils and monocytes.
The presented technique can also be used to monitor other populations of leukocytes and investigate molecules implicated in leukocyte recruitment or trafficking using other stimuli or transgenic mice.

We detail a protocol to monitor the behavior of neutrophils and monocytes in mesenteric veins under steady state and inflammatory conditions using intravital confocal microscopy on anaesthetized mice.

Abbilden Neutrophilen und Monozyten in Mesenterialvenen von Intravitalmikroskopie an narkotisierten Ratten in Echtzeit

Efficient immune response is dependent on rapid mobilization of blood leukocytes to the site of infection or injury. Investigating leukocyte migration in ...

Purification of Viral DNA for the Identification of Associated Viral and Cellular Proteins

The goal of this protocol is to isolate herpes simplex virus type 1 (HSV-1) DNA from infected cells for the identification of associated viral and cellular proteins by mass spectrometry. Although proteins that interact with viral genomes play major roles in determining the outcome of infection, a comprehensive analysis of viral genome associated proteins was not previously feasible. Here we demonstrate a method that enables the direct purification of HSV-1 genomes from infected cells. Replicating viral DNA is selectively labeled with modified nucleotides that contain an alkyne functional group. Labeled DNA is then specifically and irreversibly tagged via the covalent attachment of biotin azide via a copper(I)-catalyzed azide-alkyne cycloaddition or click reaction. Biotin-tagged DNA is purified on streptavidin-coated beads and associated proteins are eluted and identified by mass spectrometry. This method enables the selective targeting and isolation of HSV-1 replication forks or whole genomes from complex biological environments. Furthermore, adaptation of this approach will allow for the investigation of various aspects of herpesviral infection, as well as the examination of the genomes of other DNA viruses.

The goal of this protocol is to specifically tag and selectively isolate viral DNA from infected cells for the characterization of viral genome associated proteins.

Reinigung der viralen DNA für die Identifizierung von assoziierten viralen und zellulären Proteinen

The goal of this protocol is to isolate herpes simplex virus type 1 (HSV-1) DNA from infected cells for the identification of associated viral and ...

Real-time Imaging and Quantification of Fungal Biofilm Development Using a Two-Phase Recirculating Flow System

In oropharyngeal candidiasis, members of the genus Candida must adhere to and grow on the oral mucosal surface while under the effects of salivary flow. While models for the growth under flow have been developed, many of these systems are expensive, or do not allow imaging while the cells are under flow. We have developed a novel apparatus that allows us to image the growth and development of Candida albicans cells under flow and in real-time. Here, we detail the protocol for the assembly and use of this flow apparatus, as well as the quantification of data that are generated. We are able to quantify the rates that the cells attach to and detach from the slide, as well as to determine a measure of the biomass on the slide over time. This system is both economical and versatile, working with many types of light microscopes, including inexpensive benchtop microscopes, and is capable of extended imaging times compared to other flow systems. Overall, this is a low-throughput system that can provide highly detailed real-time information on the biofilm growth of fungal species under flow.

We describe the assembly, operation, and cleaning of a flow apparatus designed to image fungal biofilm formation in real time while under flow. We also provide and discuss quantitative algorithms to be used on the acquired images.

Echtzeit-Bildgebung und Quantifizierung der Pilz Biofilm-Entwicklung mit einem Zweiphasensystem rezirkulierenden Flow

In oropharyngeal candidiasis, members of the genus Candida must adhere to and grow on the oral mucosal surface while under the effects of salivary flow. ...

Image Processing Protocol for the Analysis of the Diffusion and Cluster Size of Membrane Receptors by Fluorescence Microscopy

Particle tracking on a video sequence and the posterior analysis of their trajectories is nowadays a common operation in many biological studies. Using the analysis of cell membrane receptor clusters as a model, we present a detailed protocol for this image analysis task using Fiji (ImageJ) and Matlab routines to: 1) define regions of interest and design masks adapted to these regions; 2) track the particles in fluorescence microscopy videos; 3) analyze the diffusion and intensity characteristics of selected tracks. The quantitative analysis of the diffusion coefficients, types of motion, and cluster size obtained by fluorescence microscopy and image processing provides a valuable tool to objectively determine particle dynamics and the consequences of modifying environmental conditions. In this article we present detailed protocols for the analysis of these features. The method described here not only allows single-molecule tracking detection, but also automates the estimation of lateral diffusion parameters at the cell membrane, classifies the type of trajectory and allows complete analysis thus overcoming the difficulties in quantifying spot size over its entire trajectory at the cell membrane.

Here, we present a protocol for single particle tracking image analysis that allows quantitative evaluation of diffusion coefficients, types of motion and cluster sizes of single particles detected by fluorescence microscopy.

Bildverarbeitungs-Protokoll für die Analyse der Diffusion und Cluster-Größe von Membranrezeptoren durch Fluoreszenz-Mikroskopie

Particle tracking on a video sequence and the posterior analysis of their trajectories is nowadays a common operation in many biological studies. Using ...