Questa ricerca è stata sostenuta dalla Divisione di Ricerca intramurale dell&#39;Istituto Nazionale per le allergie e malattie infettive, National Institutes of Health. Siamo grati a Johannes Huppa e Mark Davis per averci fornito con il scFv di H57 utilizzato in questi studi. RV ringrazia Keir Neumann di discussione utile durante lo sviluppo di questa tecnica.

<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. S., Medzhitov, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integration+of+cytokine+and+heterologous+receptor+signaling+pathways.">Integration of cytokine and heterologous receptor signaling pathways.</a> Nat. Immunol. 10, 333-339 (2009).</li><li>Fraser, I. D., Germain, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Navigating+the+network:+signaling+cross-talk+in+hematopoietic+cells.">Navigating the network: signaling cross-talk in hematopoietic cells.</a> Nat. Immunol. 10, 327-331 (2009).</li><li>Dustin, M. L., Starr, T., Varma, R., Thomas, V. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Supported+planar+bilayers+for+study+of+the+immunological+synapse.">Supported planar bilayers for study of the immunological synapse.</a> Curr. Protoc. Immunol. Chapter 18, 13-13 (2007).</li><li>Vardhana, S., Dustin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Supported+Planar+Bilayers+for+the+Formation+of+Study+of+Immunological+Synapses+and+Kinapse.">Supported Planar Bilayers for the Formation of Study of Immunological Synapses and Kinapse.</a> J. Vis. Exp. (19), e947-e947 (2008).</li><li>Varma, R., Campi, G., Yokosuka, T., Saito, T., Dustin, M. 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>

Tutti gli animali utilizzati in questi esperimenti sono state mantenute in uno specifico ambiente privo di agenti patogeni, e gli esperimenti sono stati approvati dal National Institutes of Health Care degli animali e del Comitato uso.

Descriviamo qui un sistema di segnalazione per studiare in antigene-specifiche cellule T primarie topo usando TIRFM e bistrati lipidici vetro supportate come APC artificiali. La tecnica si basa sul successo esprimenti proteine ​​GFP etichetta in queste cellule. Trasfezione delle cellule T è sempre un compito impegnativo. Tipicamente, consegna elettroporazione o gene usando retrovirus o lentivirus vengono utilizzati. Una tecnica non è superiore rispetto all&#39;altra, entrambi hanno i loro limiti e vantaggi. Troviamo che elettroporazione presenta i seguenti vantaggi: 1) non è necessario che le cellule attivamente divisione come è richiesto per i retrovirus ma non lentivirus, e 2) Il livello di espressione può essere controllato variando il tempo di incubazione le cellule sono prima di imaging. Il più grande svantaggio è che ci trovano molto difficile esprimere proteine ​​che sono di grandi dimensioni in cellule primarie. Abbiamo presentato un metodo che ci dà la vitalità cellulare molto buono dopo l&#39;elettroporazione. Come risultato è applicable di usarlo per raggiungere mediata silenziamento del gene siRNA. Noi descriviamo anche qui una personalizzata due canali simultanei microscopio TIRF acquisizione che è cromaticamente corretto e non richiede l&#39;allineamento separato per diverse lunghezze d&#39;onda. Queste funzionalità, tuttavia, sono disponibili commercialmente. Il nostro sistema si basa su principi di microscopia TIRF pubblicato da esperti del settore ed è più economica rispetto alle alternative commerciali. Una possibile critica del nostro progetto è che stiamo usando lo stesso angolo di incidenza per le diverse lunghezze d&#39;onda di eccitazione. Ciò comporterebbe una diversa profondità di penetrazione TIRF per lunghezze d&#39;onda di eccitazione differenti. Riteniamo che questi effetti sono piccole perché l&#39;onda evanescente è un campo di decadimento esponenziale e la profondità del campo TIRF è una funzione lineare di lunghezza d&#39;onda. Fluorofori vicino alla superficie di vetro non si è avuta differenza di intensità tra i laser due lunghezze d&#39;onda. Per fluorofori vicino al peprofondità netration, la differenza di intensità sarà 1,3 volte per le due lunghezze d&#39;onda 488 e 640 nm e 1,15 volte per il due lunghezze d&#39;onda 488 e 561 nm. Lo stesso sistema può essere utilizzato in combinazione con tecniche di risoluzione super che fanno uso di illuminazione TIRF. Abbiamo anche descritto un sistema a due fotocamera che è costruito su misura. Come il sistema TIRF, apparati simili sono anche commercialmente disponibili. Il nostro sistema offre flessibilità per cambiare i filtri ei dicroici, consentendone l&#39;uso con diverse combinazioni di lunghezze d&#39;onda. L&#39;inconveniente del nostro sistema è un grado di rotazione necessaria per allineare le due immagini. Questo problema può essere risolto utilizzando stand della fotocamera che vengono guidati piezo e offrono gradi di rotazione di allineamento. Abbiamo anche implementato con successo un sistema a due telecamera sul microscopio, in cui le telecamere sono diversi e hanno dimensioni differenti pixel. Un sistema come questo sarebbe utile se quella necessaria sensibilità in un canale ed un grande dygamma dinamica in un altro, entrambi i quali sono raramente disponibili nella camera stessa. Abbiamo usato la HQ-2 Photometrics fotocamera binning 2x2 darci una dimensione in pixel effettivi di 12,9 micron con la Quant-EM camera Photometrics che ha una dimensione del pixel di 16 micron. A mm 180 focale lunghezza del tubo è stato utilizzato per la Quant-EM e 145 millimetri di lunghezza focale lente del tubo è stato utilizzato per la HQ-fotocamera da 2. La HQ-2 è stato controllato tramite Metamorph software e la Quant-EM è stato controllato tramite micro-manager software su un computer separato in modalità trigger esterno. Il trigger esterno è stato fornito al Quant-EM fotocamera utilizzando un uscita digitale della scheda DAC misura di calcolo, che è stato implementato come uno scatto aggiuntivo di configurazione delle impostazioni di illuminazione di Metamorph. Il rapporto tra le lunghezze focali delle lenti tubo corrisponde al rapporto tra le dimensioni effettive pixel. Un allineamento rappresentante è illustrato nella figura 5.

<table border="1"><tbody><tr><td> Nome del reattivo </td><td> Azienda </td><td> Numero di catalogo </td><td> Comments </td></tr><tr><td> Amaxa Nucleofector Kit per mouse cellule T </td><td> Lonza Inc. </td><td> VPA-1006 </td><td></td></tr><tr><td> PureLink HiPure plasmide Midiprep Kit </td><td> Life Technologies </td><td> K2100-05 </td><td> Per le preparazioni di DNA endotossine gratis </td></tr><tr><td> Amaxa Nucleofector dispositivo </td><td> Lonza Inc. </td><td> AAD-1001 </td><td></td></tr><tr><td> Ricombinante murino IL-2 </td><td> Peprotech Inc. </td><td> 212-12 </td><td></td></tr><tr><td> Fluoresbrite Multifluorescent Microsfere 0.20μm </td><td> Polysciences, Inc. </td><td> 24050-5 </td><td></td></tr><tr><td> Lab-Tek II 8-ben chambered coverglass </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

Signaling viene avviata tramite il recettore delle cellule T (TCR), quando è impegnato da frammenti di peptidi antigenici legati da Complesso Maggiore di Istocompatibilità (pMHC) proteine ​​espresse sulla superficie delle cellule presentanti l&#39;antigene (APC). Il complesso TCR è composto dell&#39;eterodimero TCRαβ legame ligando che associa non covalentemente con CD3 dimeri (e le εδ εγ eterodimeri e la ζζ omodimero) 1. Dopo l&#39;impegno del recettore, le catene zeta CD3 sono fosforilate chinasi della famiglia Src, Lck. Questo porta al reclutamento della famiglia Syk chinasi, ZAP70, che viene poi fosforilato e attivato da Lck. Dopo di che, l&#39;adattatore ZAP70 fosforila proteine ​​LAT e SLP76, avviare la formazione del complesso prossimale segnalazione contenente un gran numero di differenti molecole di segnalazione 2. La formazione di questo complesso alla fine i risultati di calcio e di Ras-dipendente TRAnscription attivazione del fattore e la conseguente apertura di una complessa serie di programmi di espressione genica che danno luogo a differenziazione delle cellule T 2. Segnali TCR (e la conseguente stato di differenziazione) sono modulati da molti fattori, compresi potenza antigene e diafonia con co-stimulatory/co-inhibitory, chemochine, recettori di citochine e 3-4. Studiare l&#39;organizzazione spaziale e temporale del complesso di segnalazione prossimale in condizioni di stimolazione è, quindi, la chiave per comprendere il percorso di TCR di segnalazione così come la sua regolamentazione attraverso vie di segnalazione di altri. Un sistema modello molto utile per studiare segnalazione avviata dal TCR a livello della membrana plasmatica di cellule T è vetro supportate bistrati lipidici, come descritto in precedenza 5-6. Possono essere utilizzati per presentare pMHC complessi antigenici, adesione, e molecole co-stimolatorie di cellule T-serve come APC artificiali. Con imaging delle cellule T interagendo con labistrato lipidico totale utilizzando microscopia a fluorescenza riflessione interna (TIRFM), possiamo limitare la eccitazione di 100 nm all&#39;interno dello spazio tra il vetro e la superficie cellulare 7-8. Questo ci permette di immagine in primo luogo gli eventi di segnalazione che si verificano a livello della membrana plasmatica. Come ci interessa nell&#39;imaging l&#39;assunzione di proteine ​​di segnalazione al complesso TCR, descriviamo due telecamera TIRF sistema di imaging in cui il TCR, marcato con Fab fluorescente (frammento legante l&#39;antigene) frammenti di anticorpo H57 (purificato da ibridoma H57-597 , ATCC, ATCC Number: HB-218) che è specifico per TCRβ, e proteine ​​di segnalazione, etichettato con GFP, può essere ripreso simultaneamente e in tempo reale. Questa strategia è necessaria a causa della natura altamente dinamica sia delle cellule T e degli eventi di segnalazione che si verificano al TCR. Questa modalità di imaging ha permesso ai ricercatori di ligandi di immagini singole 9-11, nonché all&#39;assunzione di molecole di segnalazione ai recettori attivati ​​eè un sistema eccellente per studiare biochimica in-situ 12-16.

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

La compartimentazione delle proteine ​​sia all&#39;interno della membrana plasmatica o in sedi intracellulari è un meccanismo di regolazione che possono influenzare notevolmente i risultati di segnalazione, di conseguenza, per comprendere la segnalazione è importante studiare il comportamento spaziale e temporale delle proteine ​​coinvolte. Descriviamo qui un sistema basato TIRF microscopia a studiare trasduzione del segnale in cellule T, ma è ampiamente applicabile.

Una tecnica di microscopia TIRF per Real-time, Imaging simultanea del TCR e delle sue proteine ​​associate segnalazione

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

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Research

JoVE Journal

Immunology and Infection

23.7K Views.  National Institute of Allergy and Infectious Diseases, National Institutes of Health. La compartimentazione delle proteine ​​sia all'interno della membrana plasmatica o in sedi intracellulari è un meccanismo di regolazione che possono influenzare notevolmente i risultati di segnalazione, di conseguenza, per comprendere la segnalazione è importante studiare il comportamento spaziale e temporale delle proteine ​​coinvolte. Descriviamo qui un sistema basato TIRF microscopia a studiare trasduzione del segnale in cellule T, ma è ampiamente applic...

Video: 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.

In tempo reale immagini di leucotriene B 4 Migrazione cellulare mediata e BLT1 Interazioni con β-arrestina

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

Ricerca

Immunologia e infezioni

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.

Tempo reale Imaging in diretta di cellule T Signaling formazione del complesso

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.

In tempo reale Imaging del endoteliali giunzioni cellula-cellula Durante neutrofili Trasmigrazione Sotto fisiologico flusso

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.

In tempo reale Imaging di cellule mieloidi Dynamics in<em&gt; Apc<sup&gt; Min / +</sup</em&gt; Intestinale tumori da Spinning Disk Microscopia confocale

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.

Quantificazione simultanea di T-Cell Receptor Excision Circles (TREC) e Circles K-Eliminazione ricombinazione Excision (KRECs) per Real-time 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.

Analisi di<em&gt; Yersinia enterocolitica</em&gt; Effector traslocazione in cellule ospiti Utilizzando beta-lattamasi Effector Fusions

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.

Imaging neutrofili e monociti in mesenterica Veins intravitale Microscopia su topi anestetizzati in tempo reale

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.

Purificazione di DNA virale per l'identificazione delle proteine virali e cellulari associate

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.

Imaging in tempo reale e quantificazione dello sviluppo di Biofilm fungine utilizza un sistema bifase di flusso a ricircolo

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.

Elaborazione di protocollo per l'analisi della diffusione e dimensione dei Cluster di recettori di membrana mediante microscopia a fluorescenza

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

Una tecnica di microscopia TIRF per Real-time, Imaging simultanea del TCR e delle sue proteine ​​associate segnalazione

Una tecnica di microscopia TIRF per Real-time, Imaging simultanea del TCR e delle sue proteine associate segnalazione