Name: real-time imaging of axonal transport of quantum dot-labeled bdnf in primary neurons
Uploaded: 2014-09-15T15:00:00.000+00:00
Duration: 10 min 53 s
Description: Watch this Scientific Journal Video about Real-time Imaging of Axonal Transport of Quantum Dot-labeled BDNF in Primary Neurons at JoVE.com

Vorremmo ringraziare Yue (Pauline) Hu, Rachel Sinit per la loro assistenza tecnica. Lo studio è supportato da NIH concedere (PN2 EY016525) e da un finanziamento di Down Syndrome Research Foundation e il trattamento e la Larry L. Hillblom Fondazione.

Le procedure chirurgiche e animali sono eseguite rigorosamente secondo la guida NIH per la cura e l&#39;uso di animali da laboratorio. Tutti gli esperimenti che comportano l&#39;uso di animali sono approvati dal UCSD Institutional Animal Care and Use Committee. 1 plasmidi clonazione, espressione e purificazione di Mono-biotinilato BDNF (mBtBDNF) NOTA: Construct pre-proBDNFavi e Bira cDNA in pcDNA3.1 vettoriale e coesprimere nelle cellule HEK293FT 10. Purificare mBtBDNF utilizzando Ni-NTA perline secondo il metodo precedentemente pubblicata di produrre fattore maturo e biologicamente attiva di crescita nervoso monobiotinylated (mBtNGF) 10. 2 Preparazione di microfluidici Chambers Microfluidic dispositivo neurone coltura rende possibile isolare fluidicamente assoni provenienti da corpi cellulari dei neuroni. Montare camere con vetrini rivestiti di fresco giusto prima di ogni dissezione. Camere di microfluidica usatein questo protocollo sono regolarmente acquistati (vedi Materiali e tabella di attrezzature). Lavare a mano e riutilizzati camere di commercio acquistati fino a 5-6x. <ol><li> Lavaggio a mano camere di microfluidica in 1% Alconox. Risciacquare tre volte con acqua Milli-Q per 30 minuti ciascuno. Camere di lavaggio a mano di nuovo in etanolo al 70%. </li><li> Stendere camere ad asciugare su Parafilm in cappa a flusso laminare. Irradiare e sterilizzare entrambi i lati delle camere per 20 minuti sotto UV. Conservare sterilizzato camere in un piatto 15 centimetri sterile sigillato con Parafilm a temperatura ambiente. </li><li> Mettere 24 x 40 mm N. 1 vetrini in un contenitore di vetro. Mettere a bagno i coprioggetti in 35% acido cloridrico durante la notte su un rotatore. Il giorno seguente, sciacquare i vetrini tre volte per 30 minuti ciascuno con acqua. </li><li> Sterilizzare i coprioggetti uno per uno per immersione ogni coprioggetto in 100% etanolo e fiammeggiante su un becco Bunsen. Conservare coprioggetto secco in una capsula di Petri sterile e tenerlo a temperatura ambiente fino al rivestimento. </li><li> Lay out i coprioggetti in un piatto di coltura 15 cm. Coat ogni coprioggetto con 0,7 ml di 0,01% di poli-L-lisina (PLL) e incubare nel cappuccio a temperatura ambiente. </li><li> Dopo 1 ora, sciacquare i vetrini tre volte con acqua sterile. Coprioggetto secco con vuoto e posto ogni coprioggetto in un piatto di cultura 6 cm. </li><li> Per assemblare la camera microfluidica, posizionare la camera con il lato microsolchi in basso sul coprioggetto rivestito PLL con cautela per non toccare i microsolchi. Premuto delicatamente verso il basso la camera con un puntale per garantire la camera è stata ermeticamente chiusi. </li></ol> 3. Dissezione di Cultura neuronale e piastra su Chambers <ol><li> Posizionare due ippocampi E17-E18 ratto (un cervello) sezionato in un tubo da 15 ml contenente 2 ml di tampone di dissezione (HBSS, no calcio, no magnesio, con 1% pen / strep e HEPES 10 mM. Sciacquare i tessuti 3x con 5 ml dissezione tampone ogni volta. Rimuovere il buffer dissezione per quanto possibile e aggiungere 900 ml di di frescotampone ssection. </li><li> Per digerire il tessuto, aggiungere 100 ml di tripsina 10x (2,5%) nel buffer dissezione per rendere concentrazione di lavoro 1x. Posizionare il tubo conico in un bagno di 37 ° C Acque. Dopo 10 min di digestione, aggiungere 100 ml di 10 mg / ml di DNasi I a una concentrazione finale di circa 1 mg / ml. </li><li> Usando una pipetta Pasteur di vetro lucidati a fuoco, triturare delicatamente i tessuti pipettando su e giù 5-10x. Subito dopo triturazione, placare la tripsina con 2 ml di placcatura medio (Neurobasal con 10% FBS, 2 Glutamax mM, 2% B27). </li><li> Lasciare il campione nella cappa per 5 minuti per consentire eventuali detriti dei tessuti di stabilirsi sul fondo. Rimuovere con cautela 2 ml di surnatante in una sterile tubo da 15 ml pulito e centrifugare a 200 xg per 5 minuti per far sedimentare le cellule. Risospendere il pellet in 50 microlitri mezzi placcatura </li><li> Contare le cellule con emocitometro. Carico 15-20 microlitri di sospensione cellulare (~ 40.000 cellule) in uno scomparto della camera microfluidica. Posizionare la camerain incubatrice per 10 minuti per consentire alle cellule di allegare alla coprioggetto. Dopo 10 minuti, aggiungere i media più in piastra per riempire entrambi i comparti della camera. </li><li> Il secondo giorno della dissezione, sostituire completamente i terreni in piastra con i media manutenzione (Neurobasal con 2 Glutamax mM, 2% B27), sia nel corpo cellulare e il vano assone. Gli assoni dei neuroni dell&#39;ippocampo iniziano a varcare i microsolchi in giorno 3 e raggiungere il vano assone tra il giorno 5-7. Durante questo periodo di tempo, sostituire la metà dei mezzi di coltura con terreno di mantenimento fresco ogni 24 ~ 48 ore. </li></ol> 4 assonale Trasporto di QD-BDNF <ol><li> Prima di vivere l&#39;imaging di QD-BDNF trasporto assonale, esaurire BDNF sia dal corpo cellulare e assone compartimenti della camera microfluidica da sciacquare entrambi i comparti con BDNF-liberi, siero media liberi Neurobasal ogni 30 min per 2 ore. </li><li> Durante BDNF esaurimento, preparare i coniugati QD-BDNF. Mescolare 50 nM di mono-biotinilato BDNF dimero con 50 Nm coniugati QD655-streptavidina nei media Neurobasal e incubare in ghiaccio per 60 min. </li><li> Rimuovere il supporto nel vano assone e aggiungere 300 microlitri QD-BDNF con una concentrazione finale di 0,25 nM per 4 ore a 37 ° C. Per ridurre al minimo la diffusione del QD-BDNF nel vano corpo cellulare, è molto importante mantenere sempre un livello superiore di supporto nel vano corpo cellulare che nel vano assone. Lavare non legato QD-BDNF dopo incubazione prima di imaging dal vivo. </li><li> Eseguire l&#39;imaging dal vivo di trasporto QD-BDNF utilizzando un microscopio invertito dotato di un olio lente obiettivo 100X. Scaldare la portata e la camera ambientale collegato ad esso per una temperatura costante (37 ° C) e CO 2 (5%). Utilizzare un set di Texas cubi rossi di eccitazione / emissione di visualizzare il segnale QD655. </li><li> Acquisire e catturare immagini time-lapse all&#39;interno dei assoni centrali alla velocità di 1 fotogramma / sec per un totale di 2 min con una camera CCD. Utilizzare microscanalature senza assoni that non hanno QD e quindi nessun segnale di come controllo per l&#39;infiltrazione. </li><li> Analizzare il trasporto BDNF utilizzando qualsiasi software di analisi dell&#39;immagine o NIH ImageJ. </li></ol>

<ol>
	<li>Wu, 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=A+functional+dynein-microtubule+network+is+required+for+NGF+signaling+through+the+Rap1/MAPK+pathway.">A functional dynein-microtubule network is required for NGF signaling through the Rap1/MAPK pathway.</a> Traffic. 8, 1503-1520 (2007).</li><li>Wortzel, I., Seger, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ERK+Cascade:+Distinct+Functions+within+Various+Subcellular+Organelles.">The ERK Cascade: Distinct Functions within Various Subcellular Organelles.</a> Genes &amp; cancer. 2, 195-209 (2011).</li><li>Huang, E. J., Reichardt, L. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trk+receptors:+roles+in+neuronal+signal+transduction.">Trk receptors: roles in neuronal signal transduction.</a> Annual review of biochemistry. 72, 609-642 (2003).</li><li>Nonomura, T., 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=Signaling+pathways+and+survival+effects+of+BDNF+and+NT-3+on+cultured+cerebellar+granule+cells.">Signaling pathways and survival effects of BDNF and NT-3 on cultured cerebellar granule cells.</a> Brain research. Developmental brain research. 97, 42-50 (1996).</li><li>Weissmiller, A. M., Wu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+advances+in+using+neurotrophic+factors+to+treat+neurodegenerative+disorders.">Current advances in using neurotrophic factors to treat neurodegenerative disorders.</a> Translational neurodegeneration. 1, 14 (2012).</li><li>Zhang, K., 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=Defective+axonal+transport+of+Rab7+GTPase+results+in+dysregulated+trophic+signaling.">Defective axonal transport of Rab7 GTPase results in dysregulated trophic signaling.</a> The Journal of neuroscience : the official journal of the Society for Neuroscience. 33, 7451-7462 (2013).</li><li>Taylor, A. M., 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=A+microfluidic+culture+platform+for+CNS+axonal+injury,+regeneration+and+transport.">A microfluidic culture platform for CNS axonal injury, regeneration and transport.</a> Nature methods. 2, 599-605 (2005).</li><li>Cui, B., 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=One+at+a+time,+live+tracking+of+NGF+axonal+transport+using+quantum+dots.">One at a time, live tracking of NGF axonal transport using quantum dots.</a> Proceedings of the National Academy of Sciences of the United States of America. 104, 13666-13671 (2007).</li><li>Xie, W., Zhang, K., Cui, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+characterization+and+axonal+transport+of+quantum+dot+labeled+BDNF.">Functional characterization and axonal transport of quantum dot labeled BDNF.</a> Integrative biology : quantitative biosciences from nano to macro. 4, 953-960 (2012).</li><li>Sung, K., Maloney, M. T., Yang, J., Wu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+method+for+producing+mono-biotinylated,+biologically+active+neurotrophic+factors:+an+essential+reagent+for+single+molecule+study+of+axonal+transport.">A novel method for producing mono-biotinylated, biologically active neurotrophic factors: an essential reagent for single molecule study of axonal transport.</a> Journal of neuroscience methods. 200, 121-128 (2011).</li><li>Tani, T., 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=Trafficking+of+a+ligand-receptor+complex+on+the+growth+cones+as+an+essential+step+for+the+uptake+of+nerve+growth+factor+at+the+distal+end+of+the+axon:+a+single-molecule+analysis.">Trafficking of a ligand-receptor complex on the growth cones as an essential step for the uptake of nerve growth factor at the distal end of the axon: a single-molecule analysis.</a> The Journal of neuroscience : the official journal of the Society for Neuroscience. 25, 2181-2191 (2005).</li><li>Bronfman, F. C., Tcherpakov, M., Jovin, T. M., Fainzilber, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ligand-induced+internalization+of+the+p75+neurotrophin+receptor:+a+slow+route+to+the+signaling+endosome.">Ligand-induced internalization of the p75 neurotrophin receptor: a slow route to the signaling endosome.</a> The Journal of neuroscience : the official journal of the Society for Neuroscience. 23, 3209-3220 (2003).</li><li>Kruttgen, A., Heymach, J. V., Kahle, P. J., Shooter, 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=The+role+of+the+nerve+growth+factor+carboxyl+terminus+in+receptor+binding+and+conformational+stability.">The role of the nerve growth factor carboxyl terminus in receptor binding and conformational stability.</a> The Journal of biological chemistry. 272, 29222-29228 (1997).</li><li>Zuccato, C., Cattaneo, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brain-derived+neurotrophic+factor+in+neurodegenerative+diseases.">Brain-derived neurotrophic factor in neurodegenerative diseases.</a> Nature reviews. Neurology. 5, 311-322 (2009).</li><li>Gharami, K., Xie, Y., An, J. J., Tonegawa, S., Xu, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brain-derived+neurotrophic+factor+over-expression+in+the+forebrain+ameliorates+Huntington's+disease+phenotypes+in+mice.">Brain-derived neurotrophic factor over-expression in the forebrain ameliorates Huntington's disease phenotypes in mice.</a> Journal of neurochemistry. 105, 369-379 (2008).</li><li>Gauthier, L. R., 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=Huntingtin+controls+neurotrophic+support+and+survival+of+neurons+by+enhancing+BDNF+vesicular+transport+along+microtubules.">Huntingtin controls neurotrophic support and survival of neurons by enhancing BDNF vesicular transport along microtubules.</a> Cell. 118, 127-138 (2004).</li><li>Her, L. S., Goldstein, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+sensitivity+of+striatal+neurons+to+axonal+transport+defects+induced+by+mutant+huntingtin.">Enhanced sensitivity of striatal neurons to axonal transport defects induced by mutant huntingtin.</a> The Journal of neuroscience : the official journal of the Society for Neuroscience. 28, 13662-13672 (2008).</li><li>Rong, 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=Regulation+of+intracellular+trafficking+of+huntingtin-associated+protein-1+is+critical+for+TrkA+protein+levels+and+neurite+outgrowth.">Regulation of intracellular trafficking of huntingtin-associated protein-1 is critical for TrkA protein levels and neurite outgrowth.</a> The Journal of neuroscience : the official journal of the Society for Neuroscience. 26, 6019-6030 (2006).</li></ol>

Nessun conflitto di interessi dichiarati.

In questo studio, riportiamo lo sviluppo di una nuova tecnica per produrre biologicamente attivo, monobiotinylated BDNF (mBtBDNF) che può essere utilizzato per tracciare il trasporto assonale di BDNF. Con coniugando la proteina di quantum dot streptavidina, e l&#39;utilizzo di una camera microfluidica, il metodo permette di rilevare il trasporto assonale di BDNF in neuroni primari con sensibilità singola molecola, in tempo reale e con risoluzioni spaziali e temporali. Gli strumenti utilizzati in questo documento forni...

I neuroni sono cellule altamente polarizzate i cui processi lunghi e spesso altamente elaborati sono fondamentali per stabilire e mantenere la struttura e la funzione dei circuiti neurali. L&#39;assone svolge un ruolo fondamentale nel portare carichi da e sinapsi. Le proteine ​​e organelli sintetizzati nel soma cellulare devono essere trasportati attraverso gli assoni per raggiungere il terminale presinaptico per supportare la funzione neuronale. Di conseguenza, i segnali ricevuti assoni distali devono essere trasdotte e convogliati al soma. Questi processi sono essenziali per la sopravvivenza neuronale, la differenziazione e la manutenzione. In tale trasporto assonale in alcuni neuroni deve essere condotta attraverso distanze più di 1.000 volte il diametro del corpo cellulare, la possibilità è facilmente previsto che anche i piccoli deficit potrebbero avere un impatto marcatamente funzione neuronale e del circuito. Brain-derived neurotrophic factor (BDNF), un membro della famiglia dei fattori di crescita neurotrofina, è presente in maregioni cerebrali ny, tra cui l&#39;ippocampo, la corteccia cerebrale, e prosencefalo basale. BDNF svolge un ruolo cruciale nella formazione conoscenza e la memoria sostenendo la sopravvivenza, la differenziazione e la funzione dei neuroni che partecipano a circuiti cognitivi. BDNF si lega al suo recettore, il TrkB tirosina chinasi, al terminale dell&#39;assone dove attiva vie di segnalazione TrkB-mediata, tra cui la proteina chinasi attivata da mitogeni / extracellulare proteina chinasi segnale-regolata (MAPK / ERK), fosfatidilinositolo-3-chinasi (PI3K) e fosfolipasi C-gamma (PLCγ). Le proteine ​​che partecipano a queste vie di segnalazione sono confezionati su strutture vescicolari endocitiche per formare il BDNF / TrkB segnalazione endosome 1-6 che vengono poi retrograda trasportato al soma neuronale. La camera di coltura microfluidica è una piattaforma molto utile per studiare biologia assonale in condizioni normali sia in ambito di lesioni e malattia 7,8. Con assoni isolantidai corpi cellulari, il dispositivo ha permesso di studiare un trasporto specificatamente assoni 8-10. Le piattaforme basate microfluidica PDMS con 450 micron barriere microsolchi utilizzati in questo studio sono stati acquistati in commercio (vedi tabella Materials). Per esaminare i trasporti BDNF, abbiamo sviluppato una nuova tecnologia per la produzione di monobiotinylated BDNF (mBtBDNF). Abbiamo approfittato del peptide biotina accettore, AP (noto anche come AviTag). Si tratta di una sequenza di acido 15 aminoacidi che contiene un residuo di lisina che possono essere specificamente ligato ad un biotina dal coli ligasi enzima biotina Escherichia, Bira. Abbiamo fuso il AviTag al C-terminale del mouse pre-proBDNF cDNA mediante PCR (Figura 1A). Il costrutto è stato clonato nel vettore di espressione di mammifero, pcDNA3.1-myc suo vettore. Abbiamo anche clonato il DNA batterico Bira nel pcDNA3.1-myc suo vettore. I due plasmidi sono stati transitoriamente co-trasfettate in cellule HEK293FT di esprimere entrambe le proteine. Bira catalizzata la legatura di Biotin particolare per la lisina risiedere nel AviTag al C-terminale di BDNF in un rapporto 1: 1 per produrre monobiotinylated BDNF monomero. Biotinilato, maturo BDNF con una massa molecolare di circa 18 kDa è stato recuperato e purificato dal supporto utilizzando Ni-resina (Figura 1C). La biotinilazione di BDNF era completa, come giudicato dalla incapacità di rilevare non modificato BDNF mediante immunoblotting (Figura 1D). Streptavidina punti quantici coniugati QD 655, sono stati usati per etichettare mBtBDNF per fare QD-BDNF. La presenza del AviTag non interferisce con l&#39;attività di BDNF come mBtBDNF era in grado di attivare TrkB fosforilata (Figura 1E) e stimolare la crescita dei neuriti (Figura 1F) nella misura del BDNF umano ricombinante (rhBDNF). Immunostaining dimostrato che QD-BDNF colocalizzava con TrkB in assoni ippocampali, indicando che QD-BDNF è bioattivo (Figura 1G). Per studiare il trasporto BDNF, QD-BDNF è stato aggiunto al compartimento assonale distale diculture microfluidica contenenti ratto E18 neuroni dell&#39;ippocampo (Figura 2A). QD-BDNF trasporto retrogrado all&#39;interno di assoni è stato catturato da in tempo reale di immagini dal vivo del tag fluorescente rossa (supporto video S1, S2). Analizzando il chimografo generato, QD-BDNF è stato osservato per essere trasportato retrograda ad una velocità di movimento intorno 1,06 micron / sec (Figura 3A). GFP o mCherry-tagged BDNF sono stati utilizzati per tracciare il movimento assonale di BDNF. I principali svantaggi sono che non sono abbastanza luminose per gli studi di singola molecola. Inoltre, la presenza di entrambi anterograda e movimenti retrogradi BDNF rende difficile valutare se il BDNF retrograda trasportato era in un complesso neurotrofina / recettore. In questo video, dimostriamo le tecniche utilizzate per esaminare il traffico in tempo reale di QD-BDNF in camere di microfluidica con neuroni primari. Il ultrabrightness ed eccellente fotostabilità dei punti quantici makes &#39;possibile effettuare il monitoraggio a lungo termine del trasporto BDNF. Queste tecniche possono essere sfruttati per migliorare gli studi di funzione assonale in AD, HD, e altre patologie neurodegenerative.

<table><tbody><tr><td>Platinum pfx DNA polymerase&amp;nbsp;</td><td>Invitrogen</td><td>11708021</td><td></td></tr><tr><td>EcoRI&amp;nbsp;</td><td>Fermentas</td><td>FD0274</td><td></td></tr><tr><td>BamHI&amp;nbsp;</td><td>Fermentas</td><td>FD0054</td><td></td></tr><tr><td>HEK293FT cells</td><td>Invitrogen</td><td>R70007</td><td></td></tr><tr><td>DMEM-high glucose media</td><td>Mediatech</td><td>10-013-CV</td><td></td></tr><tr><td>D-biotin&amp;nbsp;</td><td>Sigma</td><td>B4639</td><td></td></tr><tr><td>TurboFect&amp;nbsp;</td><td>Fermentas</td><td>R0531</td><td></td></tr><tr><td>PMSF&amp;nbsp;&amp;nbsp;</td><td>Sigma</td><td>P7626</td><td></td></tr><tr><td>Aprotinin</td><td>Sigma</td><td>A6279</td><td></td></tr><tr><td>Ni-NTA resins</td><td>Qiagen</td><td>30250</td><td></td></tr><tr><td>Protease inhibitors cocktail</td><td>Sigma</td><td>&amp;nbsp;S8820</td><td></td></tr><tr><td>Silver staining kit&amp;nbsp;</td><td>G-Biosciences</td><td>786-30</td><td></td></tr><tr><td>Human recombinant BDNF</td><td>Genentech</td><td></td><td></td></tr><tr><td>Microfluidic chambers</td><td>Xona</td><td>SND450</td><td></td></tr><tr><td>24 x 40 mm No. 1 glass coverslips&amp;nbsp;</td><td>VWR</td><td>48393-060</td><td></td></tr><tr><td>Poly-L-Lysine&amp;nbsp;</td><td>Cultrex</td><td>3438-100-01</td><td></td></tr><tr><td>HBSS</td><td>Gibco</td><td>14185-052</td><td></td></tr><tr><td>DNase I</td><td>Roche</td><td>10104159001</td><td></td></tr><tr><td>Trypsin</td><td>Gibco</td><td>15090-046</td><td></td></tr><tr><td>Neurobasal&amp;nbsp;</td><td>Gibco</td><td>21103-049</td><td></td></tr><tr><td>FBS&amp;nbsp;</td><td>Invitrogen</td><td>16000-044</td><td></td></tr><tr><td>GlutaMax&amp;nbsp;</td><td>Invitrogen</td><td>35050-061</td><td></td></tr><tr><td>B27&amp;nbsp;&amp;nbsp;</td><td>Gibco</td><td>17504-044</td><td></td></tr><tr><td>QD655-streptavidin conjugates</td><td>Invitrogen</td><td>&amp;nbsp;Q10121MP</td><td></td></tr><tr><td>anti-Avi tag antibody</td><td>GenScript</td><td>A00674</td><td></td></tr><tr><td>streptavidin-agarose beads&amp;nbsp;</td><td>Life Technology</td><td>&amp;nbsp;SA100-04</td><td></td></tr><tr><td>Trichloroacetic acid</td><td>Sigma</td><td>T6399</td><td></td></tr><tr><td>HRP-streptavidin&amp;nbsp;</td><td>Thermo Scientific</td><td>N100</td><td></td></tr><tr><td>anti-pTrkB antibody</td><td>a generous gift from Dr M. Chao of NYU</td><td></td><td></td></tr><tr><td>anti-TrkB antibody</td><td>BD Science</td><td>610101</td><td></td></tr></tbody></table>

real-time imaging of axonal transport of quantum dot-labeled bdnf in primary neurons

BDNF svolge un ruolo importante in molti aspetti della sopravvivenza neuronale, la differenziazione e la funzione. Deficit strutturali e funzionali in assoni sono visti sempre più come una caratteristica precoce di malattie neurodegenerative, tra cui il morbo di Alzheimer (AD) e la malattia di Huntington (HD). Per quanto ancora poco chiaro è il meccanismo (s) di cui danno assonale è indotta. Abbiamo riportato lo sviluppo di una nuova tecnica per produrre biologicamente attivo, monobiotinylated BDNF (mBtBDNF) che può essere utilizzato per tracciare il trasporto assonale di BDNF. Quantum dot-marcato BDNF (QD-BDNF) è stato prodotto da coniugando quantum dot 655 a mBtBDNF. Un dispositivo di microfluidica è stato utilizzato per isolare gli assoni da corpi cellulari dei neuroni. L&#39;aggiunta di QD-BDNF al compartimento assonale consentito l&#39;imaging dal vivo di trasporto BDNF negli assoni. Abbiamo dimostrato che QD-BDNF spostato in sostanza esclusivamente retrograda, con pochissime pause, ad una velocità di spostamento di circa 1,06 micron / sec. Questo sistema può essere usato per studiare mechanisms di perturbato funzione assonale in AD o HD, così come altre malattie degenerative.

Produzione e purificazione di biologicamente attivi BDNF Mono-biotinilato Il vettore di espressione di BDNF fuso con una sequenza AviTag (GGGLNDIFEAQKIEWHE) è stato creato secondo un protocollo già pubblicato 10. La massa molecolare della proteina di lunghezza completa di fusione è stato previsto per essere ~ 32 kDa ( <a href="http://ca.expasy.org/tools/pi_tool.html" target="_blank">http://ca.expasy.org/tools/pi_tool.html</a> ) Monobiotinylated BDNF maturo con una massa molecol...

Watch this Scientific Journal Video about Real-time Imaging of Axonal Transport of Quantum Dot-labeled BDNF in Primary Neurons at JoVE.com

Real-time Imaging of Axonal Transport of Quantum Dot-labeled BDNF in Primary Neurons

Il trasporto assonale di BDNF, un fattore neurotrofico, è fondamentale per la sopravvivenza e la funzione di diverse popolazioni neuronali. Alcune malattie degenerative sono contrassegnate dalla rottura della struttura e funzione assonale. Abbiamo dimostrato le tecniche utilizzate per esaminare il traffico in tempo reale di QD-BDNF in camere di microfluidica con neuroni primari.

In tempo reale Imaging del trasporto assonale di Quantum Dot-etichettato BDNF in neuroni primari

BDNF plays an important role in several facets of neuronal survival, differentiation, and function. Structural and functional deficits in axons are ...

real-time-imaging-axonal-transport-quantum-dot-labeled-bdnf-primary

Research

JoVE Journal

Neuroscience

15.1K Views.  University of California, San Diego.  Il trasporto assonale di BDNF, un fattore neurotrofico, è fondamentale per la sopravvivenza e la funzione di diverse popolazioni neuronali. Alcune malattie degenerative sono contrassegnate dalla rottura della struttura e funzione assonale. Abbiamo dimostrato le tecniche utilizzate per esaminare il traffico in tempo reale di QD-BDNF in camere di microfluidica con neuroni primari. 

Video: Real-time Imaging of Axonal Transport of Quantum Dot-labeled BDNF in Primary Neurons

Live Imaging of Dense-core Vesicles in Primary Cultured Hippocampal Neurons

Observing and characterizing dynamic cellular processes can yield important information about cellular activity that cannot be gained from static images.  Vital fluorescent probes, particularly green fluorescent protein (GFP) have revolutionized cell biology stemming from the ability to label specific intracellular compartments and cellular structures. For example, the live imaging of GFP (and its spectral variants) chimeras have allowed for a dynamic 
analysis of the cytoskeleton, organelle transport, and membrane dynamics in a multitude of organisms and cell types [1-3].  Although live imaging has become prevalent, this approach still poses many technical challenges, particularly in primary cultured neurons.  One challenge is the expression of GFP-tagged proteins in post-mitotic neurons; the other is the ability to capture fluorescent images while minimizing phototoxicity, photobleaching, 
and maintaining general cell health.  Here we provide a protocol that describes a lipid-based transfection method that yields a relatively low transfection rate (~0.5%), however is ideal for the imaging of fully polarized neurons.  A low transfection rate is essential so that single axons and dendrites can be characterized as to their orientation to the cell body to confirm directionality of transport, i.e., anterograde v. retrograde.  Our approach to imaging 
GFP expressing neurons relies on a standard wide-field fluorescent microscope outfitted with a CCD camera, image capture software, and a heated imaging chamber. We have imaged a wide variety of organelles or structures, for example, dense-core vesicles, mitochondria, growth cones, and actin without any special optics or excitation requirements other than a fluorescent light source. Additionally, spectrally-distinct, fluorescently 
labeled proteins, e.g., GFP and dsRed-tagged proteins, can be visualized near simultaneously to characterize co-transport or other coordinated cellular events.  The imaging approach described here is flexible for a variety of imaging applications and can be adopted by a laboratory for relatively little cost provided a microscope is available.

Live cell imaging is of particular utility when studying the dynamics of organelle trafficking. Here we describe a protocol for live imaging of dense-core vesicles in cultured neurons using wide-field fluorescence microscopy. This protocol is flexible and can be adapted to image other organelles such as mitochondria, endosomes, and peroxisomes.

Immagini dal vivo di Dense-core Vescicole nella Primaria neuroni coltivati ​​ippocampale

Observing and characterizing dynamic cellular processes can yield important information about cellular activity that cannot be gained from static images.  ...

Ricerca

Biologia

Time-lapse Live Imaging and Quantification of Fast Dendritic Branch Dynamics in Developing Drosophila Neurons

Highly motile dendritic filopodia are widely present in neurons at early developmental stages. These exploratory dynamic branches sample the surrounding environment and initiate contacts with potential synaptic partners. Although the connection between dendritic branch dynamics and synaptogenesis is well established, how developmental and activity-dependent processes regulate dendritic branch dynamics is not well understood. This is partly due to the technical difficulties associated with the live imaging and quantitative analyses of these fine structures using an in vivo system. We established a method to study dendrite dynamics using Drosophila larval ventral lateral neurons (LNvs), which can be individually labeled using genetic approaches and are accessible for live imaging. Taking advantage of this system, we developed protocols to capture branch dynamics of the whole dendritic arbor of a single labeled LNv through time-lapse live imaging. We then performed post-processing to improve image quality through drift correction and deconvolution, followed by analyzing branch dynamics at the single-branch level by annotating spatial positions of all branch terminals. Lastly, we developed R scripts (Supplementary File) and specific parameters to quantify branch dynamics using the coordinate information generated by the terminal tracing. Collectively, this protocol allows us to achieve a detailed quantitative description of branch dynamics of the neuronal dendritic arbor with high temporal and spatial resolution. The methods we developed are generally applicable to sparsely labeled neurons in both in vitro and in vivo conditions.

Time-lapse Live Imaging and Quantification of Fast Dendritic Branch Dynamics in Developing Drosophila Neurons

Here, we describe the method we employed to image highly motile dendritic filopodia in a live preparation of the Drosophila larval brain, and the protocol we developed to quantify time-lapse 3D imaging datasets for quantitative assessments of dendrite dynamics in developing neurons.

Time-lapse Live Imaging e quantificazione delle dinamiche del ramo dendritico veloce nello sviluppo di neuroni della Drosophila

Highly motile dendritic filopodia are widely present in neurons at early developmental stages. These exploratory dynamic branches sample the surrounding ...

Neuroscienze

3D Particle Tracking for Noninvasive In Vivo Analysis of Synaptic Microtubule Dynamics in Dendrites and Neuromuscular Junctions of Drosophila

Microtubules (MTs) play critical roles in neuronal development, but many questions remain about the molecular mechanisms of their regulation and function. Furthermore, despite progress in understanding postsynaptic MTs, much less is known about the contributions of presynaptic MTs to neuronal morphogenesis. In particular, studies of in vivo MT dynamics in Drosophila sensory dendrites yielded significant insights into polymer-level behavior. However, the technical and analytical challenges associated with live imaging of the fly neuromuscular junction (NMJ) have limited comparable studies of presynaptic MT dynamics. Moreover, while there are many highly effective software strategies for automated analysis of MT dynamics in vitro and ex vivo, in vivo data often necessitate significant operator input or entirely manual analysis due to inherently inferior signal-to-noise ratio in images and complex cellular morphology. &#160;To address this, this study optimized a new software platform for automated and unbiased in vivo particle detection. Multiparametric analysis of live time-lapse confocal images of EB1-GFP labeled MTs was performed in both dendrites and the NMJ of Drosophila larvae and found striking differences in MT behaviors. MT dynamics were furthermore analyzed following knockdown of the MT-associated protein (MAP) dTACC, a key regulator of Drosophila synapse development, and identified statistically significant changes in MT dynamics compared to wild type. These results demonstrate that this novel strategy for the automated multiparametric analysis of both pre- and postsynaptic MT dynamics at the polymer-level significantly reduces human-in-the-loop criteria. The study furthermore shows the utility of this method in detecting distinct MT behaviors upon dTACC-knockdown, indicating a possible future application for functional screens of factors that regulate MT dynamics in vivo. Future applications of this method may also focus on elucidating cell type and/or compartment-specific MT behaviors, and multicolor correlative imaging of EB1-GFP with other cellular and subcellular markers of interest.&#160;

This study presents a noninvasive intravital neuronal imaging strategy combined with a new software strategy to achieve automated, unbiased tracking and analysis of in vivo microtubule (MT) plus-end dynamics in the sensory dendrites and the neuromuscular junctions of Drosophila.

Microtubules (MTs) play critical roles in neuronal development, but many questions remain about the molecular mechanisms of their regulation and function. ...

An Improved Protocol to Purify and Directly Mono-Biotinylate Recombinant BDNF in a Tube for Cellular Trafficking Studies in Neurons

Recombinant BDNF containing an Avi sequence (BDNFAvi) is produced in HEK293 cells and then cost-effectively purified by affinity chromatography. A reproducible protocol was developed to directly&#160;mono-biotinylate BDNFAvi with the enzyme BirA in a tube. In this reaction, mono-biotinylated BDNFAvi retains its biological activity.
Neurotrophins are target-derived growth factors playing a role in neuronal development and maintenance. They require rapid transport mechanisms along the endocytic pathway to allow long-distance signaling between different neuronal compartments. The development of molecular tools to study the trafficking of neurotrophins has enabled the precise tracking of these proteins in the cell using in vivo recording. In this protocol, we developed an optimized and cost-effective procedure for the production of mono-biotinylated BDNF. A recombinant BDNF variant containing a biotinylable avi sequence (BDNFAvi) is produced in HEK293 cells in the microgram range and then purified in an easily scalable procedure using affinity chromatography. The purified BDNF can then be homogeneously mono-biotinylated by a direct in vitro reaction with the enzyme BirA in a tube. The biological activity of the mono-biotinylated BDNF (mbtBDNF) can be conjugated to streptavidin-conjugated to different fluorophores. BDNFAvi and mbtBDNF retain their biological activity demonstrated through the detection of downstream phosphorylated targets using western blot and activation of the transcription factor CREB, respectively. Using streptavidin-quantum dots, we were able to visualize mbtBDNF internalization concomitant with activation of CREB, which was detected with a phospho-CREB specific antibody. In addition, mbtBDNF conjugated to streptavidin-quantum dots was suitable for retrograde transport analysis in cortical neurons grown in microfluidic chambers. Thus, in tube produced mbtBDNF is a reliable tool to study physiological signaling endosome dynamics and trafficking in neurons.

Recombinant BDNF containing an Avi sequence (BDNFAvi) is produced in HEK293 cells in a cost-effective manner and is purified by affinity chromatography. BDNFavi is then directly mono-biotinylated with the enzyme BirA in a tube. BDNFavi and mono-biotinylated BDNFavi retain their biological activity when compared to commercially available BDNF.

Un protocollo migliorato per purificare e direttamente mono-biotinyare recombinante BDNF in un tubo per gli studi sul traffico cellulare nei neuroni

Recombinant BDNF containing an Avi sequence (BDNFAvi) is produced in HEK293 cells and then cost-effectively purified by affinity chromatography. A ...

Imaging and Analysis of Neurofilament Transport in Excised Mouse Tibial Nerve

Neurofilament protein polymers move along axons in the slow component of axonal transport at average speeds of ~0.35-3.5 mm/day. Until recently the study of this movement in situ was only possible using radioisotopic pulse-labeling, which permits analysis of axonal transport in whole nerves with a temporal resolution of days and a spatial resolution of millimeters. To study neurofilament transport in situ with higher temporal and spatial resolution, we developed a hThy1-paGFP-NFM transgenic mouse that expresses neurofilament protein M tagged with photoactivatable GFP in neurons. Here we describe fluorescence photoactivation pulse-escape and pulse-spread methods to analyze neurofilament transport in single myelinated axons of tibial nerves from these mice ex vivo. Isolated nerve segments are maintained on the microscope stage by perfusion with oxygenated saline and imaged by spinning disk confocal fluorescence microscopy. Violet light is used to activate the fluorescence in a short axonal window. The fluorescence in the activated and flanking regions is analyzed over time, permitting the study of neurofilament transport with temporal and spatial resolution on the order of minutes&#160;and microns, respectively. Mathematical modeling can be used to extract kinetic parameters of neurofilament transport including the velocity, directional bias and pausing behavior from the resulting data. The pulse-escape and pulse-spread methods can also be adapted to visualize neurofilament transport in other nerves. With the development of additional transgenic mice, these methods could also be used to image and analyze the axonal transport of other cytoskeletal and cytosolic proteins in axons.

We describe fluorescence photoactivation methods to analyze the axonal transport of neurofilaments in single myelinated axons of peripheral nerves from transgenic mice that express a photoactivatable neurofilament protein.

Imaging e analisi del trasporto neurofilamento nel nervo tibiale del topo escresato

Neurofilament protein polymers move along axons in the slow component of axonal transport at average speeds of ~0.35-3.5 mm/day. Until recently the study ...

Time-Lapse Imaging of Neuronal Arborization using Sparse Adeno-Associated Virus Labeling of Genetically Targeted Retinal Cell Populations

Discovering mechanisms that pattern dendritic arbors requires methods to visualize, image, and analyze dendrites during development. The mouse retina is a powerful model system for the investigation of cell type-specific mechanisms of neuronal morphogenesis and connectivity. The organization and composition of retinal subtypes are well-defined, and genetic tools are available to access specific types during development. Many retinal cell types also constrain their dendrites and/or axons to narrow layers, which facilitates time-lapse imaging. Mouse retina explant cultures are well suited for live-cell imaging using confocal or multiphoton microscopy, but methods optimized for imaging dendrite dynamics with temporal and structural resolution are lacking. Presented here is a method to sparsely label and image the development of specific retinal populations marked by the Cre-Lox system. Commercially available adeno-associated viruses (AAVs) used here expressed membrane-targeted fluorescent proteins in a Cre-dependent manner. Intraocular delivery of AAVs in neonatal mice produces fluorescent labeling of targeted cell types by 4-5 days post-injection (dpi). The membrane fluorescent signals are detectable by confocal imaging and resolve fine branch structures and dynamics. High-quality videos spanning 2-4 h are acquired from imaging retinal flat-mounts perfused with oxygenated artificial cerebrospinal fluid (aCSF). Also provided is an image postprocessing pipeline for deconvolution and three-dimensional (3D) drift correction. This protocol can be used to capture several cellular behaviors in the intact retina and to identify novel factors controlling neurite morphogenesis. Many developmental strategies learned in the retina will be relevant for understanding the formation of neural circuits elsewhere in the central nervous system.

Here, we present a method for investigating neurite morphogenesis in postnatal mouse retinal explants by time-lapse confocal microscopy. We describe an approach for sparse labeling and acquisition of retinal cell types and their fine processes using recombinant adeno-associated virus vectors that express membrane-targeted fluorescent proteins in a Cre-dependent manner.

Imaging time-lapse dell'arborizzazione neuronale utilizzando l'etichettatura del virus adeno-associato sparso di popolazioni di cellule retiniche geneticamente mirate

Discovering mechanisms that pattern dendritic arbors requires methods to visualize, image, and analyze dendrites during development. The mouse retina is a ...

Expanding the Toolkit for In Vivo Imaging of Axonal Transport

Axonal transport maintains neuronal homeostasis by enabling the bidirectional trafficking of diverse organelles and cargoes. Disruptions in axonal transport have devastating consequences for individual neurons and their networks, and contribute to a plethora of neurological disorders. As many of these conditions involve both cell autonomous and non-autonomous mechanisms, and often display a spectrum of pathology across neuronal subtypes, methods to accurately identify and analyze neuronal subsets are imperative.
This paper details protocols to assess in vivo axonal transport of signaling endosomes and mitochondria in sciatic nerves of anesthetized mice. Stepwise instructions are provided to 1) distinguish motor from sensory neurons in vivo, in situ, and ex vivo by using mice that selectively express fluorescent proteins within cholinergic motor neurons; and 2) separately or concurrently assess in vivo axonal transport of signaling endosomes and mitochondria. These complementary intravital approaches facilitate the simultaneous imaging of different cargoes in distinct peripheral nerve axons to quantitatively monitor axonal transport in health and disease.

Expanding the Toolkit for In Vivo Imaging of Axonal Transport

Using transgenic fluorescent mice, detailed protocols are described to assess in vivo axonal transport of signaling endosomes and mitochondria within motor and sensory axons of the intact sciatic nerve in live animals.

Espansione del toolkit per l'imaging in vivo del trasporto assonale

Axonal transport maintains neuronal homeostasis by enabling the bidirectional trafficking of diverse organelles and cargoes. Disruptions in axonal ...

Measuring Axonal Cargo Transport in Mouse Primary Cortical Cultured Neurons

Neuronal cells are highly polarized cells that stereotypically harbor several dendrites and an axon. The length of an axon necessitates efficient bidirectional transport by motor proteins. Various reports have suggested that defects in axonal transport are associated with neurodegenerative diseases. Also, the mechanism of the coordination of multiple motor proteins has been an attractive topic. Since the axon has uni-directional microtubules, it is easier to determine which motor proteins are involved in the movement. Therefore, understanding the mechanisms underlying the transport of axonal cargo is crucial for uncovering the molecular mechanism of neurodegenerative diseases and the regulation of motor proteins. Here, we introduce the entire process of axonal transport analysis, including the culturing of mouse primary cortical neurons, transfection of plasmids encoding cargo proteins, and directional and velocity analyses without the effect of pauses. Furthermore, the open-access software "KYMOMAKER" is introduced, which enables the generation of a kymograph to highlight transport traces according to their direction and allow easier visualization of axonal transport.

The present protocol describes the whole procedure of analysis for axonal transport. In particular, the calculation of transport velocity, not including the pausing, and the visualization method using open-access software "KYMOMAKER" are shown here.

Neuronal cells are highly polarized cells that stereotypically harbor several dendrites and an axon. The length of an axon necessitates efficient ...

<meta charset="utf8"></head><body>Visualizzazione delle proteine nei neuroni primari dell'ippocampo mediante imaging di cellule vive

Using Live&#45;Cell Imaging to Measure the Effects of Pathological Proteins on Axonal Transport in Primary Hippocampal Neurons

Bidirectional transport of cargos along the axon is critical for maintaining functional synapses, neural connectivity, and healthy neurons. Axonal transport is disrupted in multiple neurodegenerative diseases, and projection neurons are particularly vulnerable because of the need to transport cellular materials over long distances and sustain substantial axonal mass. Pathological modifications of several disease-related proteins negatively affect transport, including tau, amyloid-&#946;, &#945;-synuclein, superoxide dismutase, and huntingtin, providing a potential common mechanism by which pathological proteins exert toxicity in disease. Methods to study these toxic mechanisms are necessary to understand neurodegenerative disorders and identify potential therapeutic interventions.
Here, cultured primary rodent hippocampal neurons are co-transfected with multiple plasmids to study the effects of pathological proteins on fast axonal transport using live-cell confocal imaging of fluorescently-tagged cargo proteins. We begin with the harvest, dissociation, and culturing of primary hippocampal neurons from rodents. Then, we co-transfect the neurons with plasmid DNA constructs to express fluorescent-tagged cargo protein and wild-type or mutant tau (used as an exemplar of pathological proteins). Axons are identified in live cells using an antibody that binds an extracellular&#160;domain of neurofascin, an axon initial segment protein, and an axonal region of interest is imaged to measure fluorescent cargo transport.
Using KymoAnalyzer, a freely available ImageJ macro, we extensively characterize the velocity, pause frequency, and directional cargo density of axonal transport, all of which may be affected by the presence of pathological proteins. Through this method, we identify a phenotype of increased cargo pause frequency associated with the expression of pathological tau protein. Additionally, gene-silencing shRNA constructs can be added to the transfection mix to test the role of other proteins in mediating transport disruption. This protocol is easily adaptable for use with other neurodegenerative disease-related proteins and is a reproducible method to study the mechanisms of how those proteins disrupt axonal transport.

<meta charset="utf8"></head><body>Autore in primo piano: Comprendere l'impatto delle proteine patologiche sul trasporto assonale nelle malattie neurodegenerative

Here, we demonstrate how to combine transfection of primary hippocampal rodent neurons with live-cell confocal imaging to analyze pathological protein-induced effects on axonal transport and identify mechanistic pathways mediating these effects.

In tempo reale Imaging del trasporto assonale di Quantum Dot-etichettato BDNF in neuroni primari

Riepilogo

Esplora Altri Video

PLAYLIST