Gli autori vorrei ringraziare il Post Diploma di maturità Scholars Program Office e Novartis Institutes for BioMedical Research nel suo complesso per il finanziamento di questo studio.

1. preparazione delle celle
Nota: Questo protocollo, tra cui la generazione dei dati, utilizza cellule HEK293 trasformate con un baculovirus codifica NR1 e NR2A cellule.
<ol><li>Il numero appropriato di cellule HEK293 di semi e aggiungere il virus NR1 e/o NR2A alle concentrazioni finali appropriate (da 1.00 µ l). Per un piatto di 384 pozzetti, utilizzare 10.000 cellule/pozzetto in un volume finale di 30 µ l.</li>
	<li>In alternativa, seme cellule HEK293-NR1-NR2A presso il numero di cella appropriata e il volume (per un piatto di 384 pozzetti, uso 10.000 cellule/pozzetto in un volume finale di 30 µ l). Aggiungere tetraciclina ad una concentrazione di 2 µ g/mL per indurre l'espressione di NR2A e aggiungere la protezione composta (100 µM MDL105, 519 o 5 µM CGP07066724).</li>
	<li>Nota: Il baculovirus codifica NR1 e NR2 dovrebbe avere un titolo approssimativo tra 5 x 109 - 10 x 109 unità infettive per millilitro24.</li>
</ol>2. misurazione dell'attività del recettore NMDA
<ol><li>Preparare una piastra 384 pozzetti con cellule HEK293 trasformate con cellule NR1/NR2 o HEK293-NR1-NR2A in presenza sia composto protettivo. Utilizzare un fondo chiaro, telaio nero, piastra rivestita di poli-D-lisina. Nota: Protezione con 100 µM MDL105, 519 viene utilizzato per conferire la sensibilità a glicina, mentre 5 µM CGP070667 viene utilizzato per conferire sensibilità al glutammato.</li>
	<li>Incubare la piastra a 37 ° C e 5% CO2 per 16 ore (una notte).</li>
	<li>Rimuovere la piastra dall'incubatrice e scartare delicatamente il supporto cellulare rallentando lanciare la piastra sopra un contenitore di rifiuti organici compatibili. Picchiettare delicatamente la piastra su un tovagliolo di carta per pulire il supporto i bordi della piastra e drenare qualsiasi media rimanenti.</li>
	<li>Preparare il calcium6-colorante solubilizzanti un flaconcino di colorante calcium6 (1 dimensioni piastra) in 10 mL di tampone di incubazione (HBSS pH 7.5, 20 mM HEPES, 1 mM MgCl2, probenecid 1 mM). Incubare la piastra per 2 ore a 37 ° C e 5% CO2.</li>
	<li>Rimuovere la piastra dall'incubatore e lasciare che le celle regolare a temperatura ambiente per 10 minuti.</li>
	<li>Versare delicatamente il calcium6-colorante come descritto al punto 2.3 e aggiungere 30 µ l di tampone di dosaggio (HBSS pH 7.5, 20 mM HEPES, 1,8 mM CaCl2, probenecid 1 mM).</li>
	<li>Ripetere il passaggio 2.6 due volte per un totale di 3 lavaggi. Lasciare 30 µ l di tampone del saggio sulle cellule dopo l'ultimo lavaggio.</li>
	<li>Lasciare che le celle riposare per 5 minuti a temperatura ambiente.</li>
	<li>Preparare la piastra di ligando facendo un 4 volte stock di 400 µM glicina e 400 µM glutammato (concentrazione finale di 100 µM; concentrazione ottimale di ligandi deve essere determinato come descritto di seguito). Trasferire un minimo di 25 µ l di brodo di ligando in una piastra di fondo V 384 pozzetti.</li>
	<li>Caricare la piastra ligando e cella in Franzese (sistema funzionale di Screening di stupefacenti).</li>
	<li>Misurare la fluorescenza di base (Fo) della piastra cellulare per 30 secondi. Trasferire 10 µ l di brodo ligando nella piastra cellulare utilizzando la funzione di erogazione di scenografo e misura il flusso di calcio registrando fluorescenza calcium6-colorante per 5 minuti.</li>
	<li>Calcolare il rapporto di massima fluorescenza dividendo la massima fluorescenza ottenuta mediante la fluorescenza di base (Fo).</li>
</ol>3. ottimizzazione dei livelli di espressione di NMDAR
<ol><li>Per determinare la quantità ottimale di baculovirus utilizzare, eseguire una titolazione del virus sia NR1 e NR2A. Preparare una piastra 384 pozzetti con cellule HEK293 (raccomandazione di 10.000 cellule/pozzetto, 30 µ l di media) e includono i composti di protezione come descritto al punto 2.1.</li>
	<li>Aggiungere quantità variabili del virus NR1 in righe diverse della piastra (ad esempio: aggiungere rispettivamente 0 µ l, 2 µ l, 1 µ l, 0,5 µ l e 0,25 µ l in righe A-E). Aggiungere duplicati per accuratezza dei dati.</li>
	<li>Aggiungere quantità variabili del virus NR2A in diverse colonne del piatto (ad esempio: aggiungere rispettivamente 0 µ l, 2 µ l, 1 µ l, 0,5 µ l e 0,25 µ l in righe A-E). Aggiungere duplicati per accuratezza dei dati.</li>
	<li>Incubare la piastra a 37 ° C e 5% CO2 per 16 ore (una notte).</li>
	<li>Determinare il rapporto ottimale e la quantità dei virus NR1 e NR2A eseguendo una misurazione del flusso di calcio su Franzese (Vedi sopra).</li>
</ol>4. ligando titolazione
<ol><li>Preparare le celle come descritto al punto 2.3.</li>
	<li>Preparare diluizioni di ogni ligand in presenza di saturare le concentrazioni (100 µM) altri del ligand come una soluzione di riserva 4 volte. Ad esempio: per una concentrazione di prova finale di 10 µM di glicina, preparare una soluzione stock di 40 µM di glicina compreso 400 µM glutammato.</li>
	<li>Procedere con la misurazione di Franzese come descritto al punto 2.11.</li>
</ol>5. composti test
<ol><li>Preparare le celle come descritto nel passaggio 1.</li>
	<li>Preparare la piastra di ligando con uno stock di 5 volte della concentrazione del ligando finale nel tampone.</li>
	<li>Preparare la piastra di composti con il brodo 4 volte della concentrazione di composti nel buffer di analisi finale desiderata. Per una concentrazione finale composta di 10 µM nel tampone, preparare una soluzione stock di 40 µM.<ol>
<li>Mantenere costante la concentrazione di dimetilsolfossido (DMSO) attraverso tutti i campioni di preparare una pre-diluizione del composto in DMSO prima ulteriore diluizione nel buffer di analisi.</li>
		<li>Per una reazione al dosaggio del composto nel test finale compresa tra 3 e 30 µM, preparare una pre-diluizione del composto in DMSO che vanno da 1 a 10 mM. Diluire quelli nel tampone alla concentrazione stock 4 volte. La concentrazione finale di DMSO non deve superare 0,5%. Nota: Si consiglia di testare ogni campione in triplici copie.</li>
	</ol>
</li>
	<li>Caricare il ligando, composto e piastra in Franzese.</li>
	<li>Misurare la fluorescenza di base per 30 secondi.</li>
	<li>Aggiungere 10 µ l di brodo composto e misurare la fluorescenza per 5 minuti.</li>
	<li>Aggiungere 10 µ l di brodo di ligando e misurare la fluorescenza per 5 minuti.</li>
	<li>Determinare l'integrale del rapporto fluorescenza calcolando l'area sotto la curva dei rapporti fluorescente durante gli ultimi 5 minuti della misurazione. Nota: In alternativa, il rapporto massimo di fluorescenza dopo aggiunta di legante può essere utilizzato per l'analisi.</li>
</ol>

<ol>
	<li>Farrall, A. J., Wardlaw, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood-brain+barrier:+ageing+and+microvascular+disease--systematic+review+and+meta-analysis.">Blood-brain barrier: ageing and microvascular disease--systematic review and meta-analysis.</a> Neurobiology of Aging. 30 (3), 337-352 (2009).</li><li>Walhovd, K. B., Fjell, A. M., Espeseth, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cognitive+decline+and+brain+pathology+in+aging--need+for+a+dimensional,+lifespan+and+systems+vulnerability+view.">Cognitive decline and brain pathology in aging--need for a dimensional, lifespan and systems vulnerability view.</a> Scandinavian Journal of Psychology. 55 (3), 244-254 (2014).</li><li>Wittchen, H. U., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+size+and+burden+of+mental+disorders+and+other+disorders+of+the+brain+in+Europe+2010.">The size and burden of mental disorders and other disorders of the brain in Europe 2010.</a> European Neuropsychopharmacology. 21 (9), 655-679 (2011).</li><li>Traynelis, S. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glutamate+receptor+ion+channels:+structure,+regulation,+and+function.">Glutamate receptor ion channels: structure, regulation, and function.</a> Pharmacological Reviews. 62 (3), 405-496 (2010).</li><li>Mony, L., Kew, J. N., Gunthorpe, M. J., Paoletti, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allosteric+modulators+of+NR2B-containing+NMDA+receptors:+molecular+mechanisms+and+therapeutic+potential.">Allosteric modulators of NR2B-containing NMDA receptors: molecular mechanisms and therapeutic potential.</a> British Journal of Pharmacology. 157 (8), 1301-1317 (2009).</li><li>Lau, C. G., Zukin, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NMDA+receptor+trafficking+in+synaptic+plasticity+and+neuropsychiatric+disorders.">NMDA receptor trafficking in synaptic plasticity and neuropsychiatric disorders.</a> Nature Reviews Neuroscience. 8 (6), 413-426 (2007).</li><li>Zhou, Q., Sheng, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NMDA+receptors+in+nervous+system+diseases.">NMDA receptors in nervous system diseases.</a> Neuropharmacology. 74, 69-75 (2013).</li><li>Paoletti, P., Bellone, C., Zhou, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NMDA+receptor+subunit+diversity:+impact+on+receptor+properties,+synaptic+plasticity+and+disease.">NMDA receptor subunit diversity: impact on receptor properties, synaptic plasticity and disease.</a> Nature Reviews Neuroscience. 14, 383 (2013).</li><li>Sanz-Clemente, A., Nicoll, R. A., Roche, 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=Diversity+in+NMDA+receptor+composition:+many+regulators,+many+consequences.">Diversity in NMDA receptor composition: many regulators, many consequences.</a> Neuroscientist. 19 (1), 62-75 (2013).</li><li>Neyton, J., Paoletti, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relating+NMDA+receptor+function+to+receptor+subunit+composition:+limitations+of+the+pharmacological+approach.">Relating NMDA receptor function to receptor subunit composition: limitations of the pharmacological approach.</a> Journal of Neuroscience. 26 (5), 1331-1333 (2006).</li><li>Hunt, D. L., Castillo, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synaptic+plasticity+of+NMDA+receptors:+mechanisms+and+functional+implications.">Synaptic plasticity of NMDA receptors: mechanisms and functional implications.</a> Current Opinion in Neurobiology. 22 (3), 496-508 (2012).</li><li>Huganir, R. L., Nicoll, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=AMPARs+and+synaptic+plasticity:+the+last+25+years.">AMPARs and synaptic plasticity: the last 25 years.</a> Neuron. 80 (3), 704-717 (2013).</li><li>Shimomura, H., 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=Glycine+plays+a+crucial+role+as+a+co-agonist+of+NMDA+receptors+in+the+neuronal+circuit+generating+body+movements+in+rat+fetuses.">Glycine plays a crucial role as a co-agonist of NMDA receptors in the neuronal circuit generating body movements in rat fetuses.</a> Neuroscience Research. 97, 13-19 (2015).</li><li>Tajima, N., 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=Activation+of+NMDA+receptors+and+the+mechanism+of+inhibition+by+ifenprodil.">Activation of NMDA receptors and the mechanism of inhibition by ifenprodil.</a> Nature. 534 (7605), 63-68 (2016).</li><li>Mayer, M. L., Westbrook, G. L., Guthrie, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Voltage-dependent+block+by+Mg2++of+NMDA+responses+in+spinal+cord+neurones.">Voltage-dependent block by Mg2+ of NMDA responses in spinal cord neurones.</a> Nature. 309 (5965), 261-263 (1984).</li><li>Zhu, S., 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=Mechanism+of+NMDA+Receptor+Inhibition+and+Activation.">Mechanism of NMDA Receptor Inhibition and Activation.</a> Cell. 165 (3), 704-714 (2016).</li><li>Yildiz-Unal, A., Korulu, S., Karabay, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroprotective+strategies+against+calpain-mediated+neurodegeneration.">Neuroprotective strategies against calpain-mediated neurodegeneration.</a> Neuropsychiatric Disease and Treatment. 11, 297-310 (2015).</li><li>Gascon, S., Sobrado, M., Roda, J. M., Rodriguez-Pena, A., Diaz-Guerra, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Excitotoxicity+and+focal+cerebral+ischemia+induce+truncation+of+the+NR2A+and+NR2B+subunits+of+the+NMDA+receptor+and+cleavage+of+the+scaffolding+protein+PSD-95.">Excitotoxicity and focal cerebral ischemia induce truncation of the NR2A and NR2B subunits of the NMDA receptor and cleavage of the scaffolding protein PSD-95.</a> Molecular Psychiatry. 13 (1), 99-114 (2008).</li><li>Uttara, B., Singh, A. V., Zamboni, P., Mahajan, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidative+stress+and+neurodegenerative+diseases:+a+review+of+upstream+and+downstream+antioxidant+therapeutic+options.">Oxidative stress and neurodegenerative diseases: a review of upstream and downstream antioxidant therapeutic options.</a> Current Neuropharmacology. 7 (1), 65-74 (2009).</li><li>Hansen, K. 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=Implementation+of+a+fluorescence-based+screening+assay+identifies+histamine+H3+receptor+antagonists+clobenpropit+and+iodophenpropit+as+subunit-selective+N-methyl-D-aspartate+receptor+antagonists.">Implementation of a fluorescence-based screening assay identifies histamine H3 receptor antagonists clobenpropit and iodophenpropit as subunit-selective N-methyl-D-aspartate receptor antagonists.</a> Journal of Pharmacology and Experimental Therapeutics. 333 (3), 650-662 (2010).</li><li>Bettini, E., 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=Identification+and+characterization+of+novel+NMDA+receptor+antagonists+selective+for+NR2A-+over+NR2B-containing+receptors.">Identification and characterization of novel NMDA receptor antagonists selective for NR2A- over NR2B-containing receptors.</a> Journal of Pharmacology and Experimental Therapeutics. 335 (3), 636-644 (2010).</li><li>Feuerbach, D., Loetscher, E., Neurdin, S., Koller, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+pharmacology+of+the+human+NMDA-receptor+subtypes+R1-2A,+R1-2B,+R1-2C+and+R1-2D+using+an+inducible+expression+system.">Comparative pharmacology of the human NMDA-receptor subtypes R1-2A, R1-2B, R1-2C and R1-2D using an inducible expression system.</a> European Journal of Pharmacology. 637 (1-3), 46-54 (2010).</li><li>Hansen, K. B., Brauner-Osborne, H., Egebjerg, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacological+characterization+of+ligands+at+recombinant+NMDA+receptor+subtypes+by+electrophysiological+recordings+and+intracellular+calcium+measurements.">Pharmacological characterization of ligands at recombinant NMDA receptor subtypes by electrophysiological recordings and intracellular calcium measurements.</a> Combinatorial Chemistry and High Throughput Screening. 11 (4), 304-315 (2008).</li><li>Guo, H., 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+NMDA-receptor+calcium+influx+assay+sensitive+to+stimulation+by+glutamate+and+glycine/D-serine.">A NMDA-receptor calcium influx assay sensitive to stimulation by glutamate and glycine/D-serine.</a> Scientific Reports. 7 (1), 11608 (2017).</li><li>Hackos, D. H., 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=Positive+Allosteric+Modulators+of+GluN2A-Containing+NMDARs+with+Distinct+Modes+of+Action+and+Impacts+on+Circuit+Function.">Positive Allosteric Modulators of GluN2A-Containing NMDARs with Distinct Modes of Action and Impacts on Circuit Function.</a> Neuron. 89 (5), 983-999 (2016).</li><li>Romero-Hernandez, A., Furukawa, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+Mode+of+Antagonist+Binding+in+NMDA+Receptors+Revealed+by+the+Crystal+Structure+of+the+GluN1-GluN2A+Ligand-Binding+Domain+Complexed+to+NVP-AAM077.">Novel Mode of Antagonist Binding in NMDA Receptors Revealed by the Crystal Structure of the GluN1-GluN2A Ligand-Binding Domain Complexed to NVP-AAM077.</a> Molecular Pharmacology. 92 (1), 22-29 (2017).</li><li>Auberson, Y. P., 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=5-Phosphonomethylquinoxalinediones+as+competitive+NMDA+receptor+antagonists+with+a+preference+for+the+human+1A/2A,+rather+than+1A/2B+receptor+composition.">5-Phosphonomethylquinoxalinediones as competitive NMDA receptor antagonists with a preference for the human 1A/2A, rather than 1A/2B receptor composition.</a> Bioorganic and Medicinal Chemistry Letters. 12 (7), 1099-1102 (2002).</li><li>Danysz, W., Parsons, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glycine+and+N-methyl-D-aspartate+receptors:+physiological+significance+and+possible+therapeutic+applications.">Glycine and N-methyl-D-aspartate receptors: physiological significance and possible therapeutic applications.</a> Pharmacological Reviews. 50 (4), 597-664 (1998).</li><li>Liu, M. 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=Topoisomerase+II+Inhibitors+Can+Enhance+Baculovirus-Mediated+Gene+Expression+in+Mammalian+Cells+through+the+DNA+Damage+Response.">Topoisomerase II Inhibitors Can Enhance Baculovirus-Mediated Gene Expression in Mammalian Cells through the DNA Damage Response.</a> International Journal of Molecular Science. 17 (6), (2016).</li></ol>

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Il successo di questo test dipende in gran parte la salute delle cellule HEK utilizzato. Le cellule in fase di crescita esponenziale e con numero di passaggio basso dovrebbe essere usato. Questo test comporta molti trasferimenti e aggiunte di soluzioni, così uso attenzione garantirà maggiore precisione nei suoi risultati. Concentrazioni di composti e di tutti gli altri reagenti dovrebbero essere anche controllato per minimizzare gli errori. Quando si sostituisce media delle cellule con il buffer di analisi per il dosag...

Con attuali progressi in medicina, l'aspettativa di vita è aumentata in modo significativo; Tuttavia, così ha la prevalenza delle malattie età-correlate. Malattie del sistema nervoso centrale (CNS) come schizofrenia, sclerosi laterale amiotrofica (ALS), morbo di Alzheimer e morbo di Parkinson, tra gli altri, non fanno eccezione e sono stati progettati per aumentare sopra il prossimo decennio1, 2 , 3. il malfunzionamento del noto come recettori N-metil-D-aspartato (NMDAR) dei recettori ionotropi del glutammato è stato collegato al morbo di Alzheimer, schizofrenia, trauma cranico, ictus, diabete e glaucoma tra gli altri, che garantisce la bisogno di studiare la loro biologia per lo sviluppo di terapie efficaci, modificante la malattia4,5,6,7.
NMDARs sono composti da quattro monomeri o subunità4,8,9. La composizione strutturale della NMDAR Mostra variabilità inerente allo sviluppo e regionali entro il cervello7,10. NMDARs sono coinvolti nella plasticità sinaptica, cognizione e la generazione dei ritmi per respirazione e locomozione11,12,13. Come un canale voltaggio-dipendente, è in gran parte non conduttore al potenziale di membrana a riposo (-70 mV) e viene bloccato da magnesio per prevenire ulteriori permeazione degli ioni. Il canale è attivato dall'associazione di due ligandi, glutammato e glicina/D-serina, e una depolarizzazione simultanea alla membrana sinaptica mediata da recettori AMPA, un'altra sottoclasse di recettori ionotropici del glutammato. La depolarizzazione rimuove il blocco di magnesio di NMDAR, consentendo l'afflusso dei cationi, in particolare calcio14,15,16. Anche se l'attivazione di NMDAR è essenziale per la sopravvivenza delle cellule, attivazione eccessiva può portare a cellule morte17,18,19 attraverso excitotoxicity. Questo, oltre la complessa natura del recettore, rende difficile effettuare studi necessari per lo sviluppo di terapie efficaci.
Sono stati sviluppati diversi metodi per studiare la NMDAR. Tuttavia, ciascuno di essi è corredato da avvertimenti. Ad esempio, una tecnica ampiamente utilizzata è un'analisi di fluorescenza-basata che misura i cambiamenti di NMDAR-mediati in calcio intracellulare in una linea cellulare stabile sotto il controllo di un promotore inducibile tetraciclina (Tet-On)20. Tuttavia, in questo sistema, le concentrazioni di sopramassimale di ligandi che sono necessari e l'obbligo che gli inibitori di NMDAR sono presenti durante la misurazione rende quasi impossibile rilevare l'attività dell'antagonista competitivo. In altri sistemi simili, l'espressione del recettore funzionale provoca tossicità, che richiedono di bloccanti dei canali come ketamina21,22 per preservare le colture cellulari. Questi antagonisti sedersi al centro del recettore e sono difficili da lavare fuori, soprattutto in un formato basato su piastra, in modo da interferire con gli studi funzionali del recettore. Infine, nelle misurazioni elettrofisiologiche come patch di bloccaggio, c'è la velocità effettiva limitata e studi su larga scala sono molto costosi23. Nonostante, i sistemi di cui sopra sono insensibili alla stimolazione di glicina; quindi, studiando attività di glicina-dipendente del NMDAR diventa una sfida.
Qui, descriviamo un nuovo approccio per lo studio di NMDAR che supera le limitazioni discusse. La nostra tecnica sfrutta il sistema di espressione di baculovirus per esprimere il recettore a livello funzionale con un rapporto ottimale delle subunità in meno di 16 ore. Inoltre, l'uso di baculovirus consente un approccio semplice e combinatorio, che fornisce un'ampia caratterizzazione dei sottotipi distinti ricombinante NMDAR. A differenza di altri saggi, questo protocollo non richiede bloccanti dei canali a causa dell'uso di antagonisti deboli. Vantaggio più forte del metodo è quello dopo interruzione dell'antagonista debole, il recettore è sensibile alla modulazione dei siti individuali della glicina e del glutammato-associazione oltre a doppia modulazione di glutammato e glicina/D-serina ligand-legantesi siti. Il dosaggio ricapitola noto farmacologia del recettore NMDAR e gli effetti dei suoi noti modulatori positivi e negativi. Infine, generazione di questo test in vitro cellular supera la tossicità cellulare causata da afflusso del calcio eccessivo e permette per studi funzionali del recettore in un modo ad alta velocità, che può accelerare le scoperte dei modulatori NMDAR negli Stati di malattia.

<table><tbody><tr><td>HEK-293</td><td>ATCC</td><td>CRL-1573</td><td></td></tr><tr><td>Human NMDA (NR1/NR2A) Receptor Cell Line</td><td>ChanTest Corporation</td><td>CT6120</td><td></td></tr><tr><td>pFastBac Dual Expression Vector</td><td>ThermoFisher Scientific</td><td>10712-024</td><td></td></tr><tr><td>Corning 384-well Clear Flat Bottom Microplate</td><td>Corning Life Sciences</td><td>3844</td><td></td></tr><tr><td>FLIPR Calcium 6-QF Assay Kit</td><td>Molecular Devices</td><td>R8192</td><td></td></tr><tr><td>Glycine</td><td>Sigma-Aldrich</td><td>G7126</td><td></td></tr><tr><td>Glutamate</td><td>Sigma-Aldrich</td><td>49621</td><td></td></tr><tr><td>D-serine</td><td>Sigma-Aldrich</td><td>S4250</td><td></td></tr><tr><td>L701,324</td><td>Tocris</td><td>907</td><td></td></tr><tr><td>HEPES Buffer</td><td>Boston Bio Product</td><td>BB-103</td><td></td></tr><tr><td>Magnesium Chloride Solution</td><td>Sigma-Aldrich</td><td>63069</td><td></td></tr><tr><td>Calcium Chloride</td><td>VWR</td><td>E506</td><td></td></tr><tr><td>HBSS</td><td>ThermoFisher Scientific</td><td>14025-092</td><td></td></tr><tr><td>Probenecid</td><td>ThermoFisher Scientific</td><td>P36400</td><td></td></tr><tr><td>DMEM/F-12, GlutaMAX media</td><td>ThermoFisher Scientific</td><td>10565018</td><td></td></tr><tr><td>MDL105,519</td><td>NIBR</td><td>Synthesized in house</td><td></td></tr><tr><td>NVP-AAM077</td><td>NIBR</td><td>Synthesized in house</td><td></td></tr><tr><td>CGP070667</td><td>NIBR</td><td>Synthesized in house</td><td></td></tr></tbody></table>

a high-throughput calcium-flux assay to study nmda-receptors with sensitivity to glycine/d-serine and glutamate

I recettori N-metil-D-aspartato (NMDA) (NMDAR) sono classificati come recettori ionotropici per il glutammato e hanno importanti ruoli nell'apprendimento e nella memoria. Malfunzionamento NMDAR, espresso come entrambi sopra - o sotto - activity causata da mutazioni, espressione alterata, traffico o localizzazione, può contribuire a numerose malattie, soprattutto nel sistema nervoso centrale. Di conseguenza, comprensione della biologia del ricevitore, nonché facilitare la scoperta di composti e piccole molecole è cruciale nei continui sforzi per combattere le malattie neurologiche. Attuali approcci allo studio del recettore presentano limitazioni tra cui bassa velocità effettiva, costo elevato e l'impossibilità di studiare le relative abilità funzionale dovuto la necessaria presenza di bloccanti dei canali per evitare eccitotossicità mediata NMDAR. Inoltre, gli attuali sistemi di dosaggio sono sensibili alla stimolazione da glutammato solo e la mancanza di sensibilità alla stimolazione da glicina, altri co-ligando del NMDAR. Qui, presentiamo il primo test basati su piastra con potenza di alto-rendimento per studiare un recettore NMDA con sensibilità sia co-leganti, glutammato e glicina-serina/D. Questo approccio consente lo studio delle diverse composizioni di subunità NMDAR e studi funzionali del recettore in modalità glicina - e/o sensibili al glutammato. Inoltre, il metodo non richiede la presenza di inibitori durante le misurazioni. Gli effetti di modulatori allosterici positivi e negativi possono essere rilevati con questo test e la farmacologia nota di NMDAR è stata replicata nel nostro sistema. Questa tecnica supera le limitazioni dei metodi esistenti ed è conveniente. Noi crediamo che questa tecnica novella ad accelerare la scoperta di terapie per patologie mediate da NMDAR.

Prima di testare gli effetti di piccole molecole, si devono determinare i livelli di espressione ottimale di NMDARs così come le concentrazioni di ligando ottimale. Come descritto, HEK293 cellule sono state seminate a 10.000 cellule per pozzetto di una piastra a 384 pozzetti, in presenza di 5 µM CGP060667, quindi trasdotte con quantità variabili di NR1 e NR2A virus. Dopo incubazione overnight, indotta da legante di calcio è stato misurato il flusso (Figura 1</stro...

Watch this Scientific Journal Video about A High-throughput Calcium-flux Assay to Study NMDA-receptors with Sensitivity to Glycine/D-serine and Glutamate at JoVE.com

A High-throughput Calcium-flux Assay to Study NMDA-receptors with Sensitivity to Glycine/D-serine and Glutamate

Un'analisi di flusso di calcio High-throughput per studiare i recettori NMDA con sensibilità al glutammato e glicina/D-serina

L'obiettivo del presente protocollo è quello di facilitare lo studio dei recettori NMDA (NMDAR) a scala più ampia e consentire l'esame degli effetti modulatory di piccole molecole e le loro applicazioni terapeutiche.

N-methyl-D-aspartate (NMDA) receptors (NMDAR) are classified as ionotropic glutamate receptors and have critical roles in learning and memory. NMDAR ...

a-high-throughput-calcium-flux-assay-to-study-nmda-receptors-with

Research

JoVE Journal

Neuroscience

9.2K Views.  Novartis Institutes for BioMedical Research. L'obiettivo del presente protocollo è quello di facilitare lo studio dei recettori NMDA (NMDAR) a scala più ampia e consentire l'esame degli effetti modulatory di piccole molecole e le loro applicazioni terapeutiche.

Video: A High-throughput Calcium-flux Assay to Study NMDA-receptors with Sensitivity to Glycine/D-serine and Glutamate

Glutamine Flux Imaging Using Genetically Encoded Sensors

Genetically encoded sensors allow real-time monitoring of biological molecules at a subcellular resolution. A tremendous variety of such sensors for biological molecules became available in the past 15 years, some of which became indispensable tools that are used routinely in many laboratories.
One of the exciting applications of genetically encoded sensors is the use of these sensors in investigating cellular transport processes. Properties of transporters such as kinetics and substrate specificities can be investigated at a cellular level, providing possibilities for cell-type specific analyses of transport activities. In this article, we will demonstrate how transporter dynamics can be observed using genetically encoded glutamine sensor as an example. Experimental design, technical details of the experimental settings, and considerations for post-experimental analyses will be discussed.

This article will demonstrate how to monitor glutamine dynamics in live cells using FRET. Genetically encoded sensors allow real-time monitoring of biological molecules at a subcellular resolution. Experimental design, technical details of the experimental settings, and considerations for post-experimental analyses will be discussed for genetically encoded glutamine sensors.

La glutammina Flux Imaging Utilizzando sensori geneticamente codificato

Genetically encoded sensors allow real-time monitoring of biological molecules at a subcellular resolution. A tremendous variety of such sensors for ...

Ricerca

Bioingegneria

Multi-photon Intracellular Sodium Imaging Combined with UV-mediated Focal Uncaging of Glutamate in CA1 Pyramidal Neurons

Multi-photon fluorescence microscopy has enabled the analysis of morphological and physiological parameters of brain cells in the intact tissue with high spatial and temporal resolution. Combined with electrophysiology, it is widely used to study activity-related calcium signals in small subcellular compartments such as dendrites and dendritic spines. In addition to calcium transients, synaptic activity also induces postsynaptic sodium signals, the properties of which are only marginally understood. Here, we describe a method for combined whole-cell patch-clamp and multi-photon sodium imaging in cellular micro domains of central neurons. Furthermore, we introduce a modified procedure for ultra-violet (UV)-light-induced uncaging of glutamate, which allows reliable and focal activation of glutamate receptors in the tissue. To this end, whole-cell recordings were performed on Cornu Ammonis subdivision 1 (CA1) pyramidal neurons in acute tissue slices of the mouse hippocampus. Neurons were filled with the sodium-sensitive fluorescent dye SBFI through the patch-pipette, and multi-photon excitation of SBFI enabled the visualization of dendrites and adjacent spines. To establish UV-induced focal uncaging, several parameters including light intensity, volume affected by the UV uncaging beam, positioning of the beam as well as concentration of the caged compound were tested and optimized. Our results show that local perfusion with caged glutamate (MNI-Glutamate) and its focal UV-uncaging result in inward currents and sodium transients in dendrites and spines. Time course and amplitude of both inward currents and sodium signals correlate with the duration of the uncaging pulse. Furthermore, our results show that intracellular sodium signals are blocked in the presence of blockers for ionotropic glutamate receptors, demonstrating that they are mediated by sodium influx though this pathway. In summary, our method provides a reliable tool for the investigation of intracellular sodium signals induced by focal receptor activation in intact brain tissue.

We describe the combination of focal UV-induced photo-activation of neuro-active compounds with whole-cell patch-clamp and multi-photon imaging of intracellular sodium transients in dendrites and spines of hippocampal neurons in acute tissue slices of the mouse brain.

Multi-fotone intracellulare di sodio Imaging Combinato con UV-mediata uncaging focale di glutammato in neuroni piramidali CA1

Multi-photon fluorescence microscopy has enabled the analysis of morphological and physiological parameters of brain cells in the intact tissue with high ...

Neuroscienze

A "Dual-Addition" Calcium Fluorescence Assay for the High-Throughput Screening of Recombinant G Protein-Coupled Receptors

G protein-coupled receptors (GPCRs) represent the largest superfamily of receptors and are the targets of numerous human drugs. High-throughput screening (HTS) of random small molecule libraries against GPCRs is used by the pharmaceutical industry for target-specific drug discovery. In this study, an HTS was employed to identify novel small-molecule ligands of invertebrate-specific neuropeptide GPCRs as probes for physiological studies of vectors of deadly human and veterinary pathogens.
The invertebrate-specific kinin receptor was chosen as a target because it regulates many important physiological processes in invertebrates, including diuresis, feeding, and digestion. Furthermore, the pharmacology of many invertebrate GPCRs is poorly characterized or not characterized at all; therefore, the differential pharmacology of these groups of receptors with respect to the related GPCRs in other metazoans, especially humans, adds knowledge to the structure-activity relationships of GPCRs as a superfamily. An HTS assay was developed for cells in 384-well plates for the discovery of ligands of the kinin receptor from the cattle fever tick, or southern cattle tick, Rhipicephalus microplus. The tick kinin receptor was stably expressed in CHO-K1 cells.
The kinin receptor, when activated by endogenous kinin neuropeptides or other small molecule agonists, triggers Ca2+ release from calcium stores into the cytoplasm. This calcium fluorescence assay combined with a &#34;dual-addition&#34; approach can detect functional agonist and antagonist &#34;hit&#34; molecules in the same assay plate. Each assay was conducted using drug plates carrying an array of 320 random small molecules. A reliable Z&#39; factor of 0.7 was obtained, and three agonist and two antagonist hit molecules were identified when the HTS was at a 2 &#181;M final concentration. The calcium fluorescence assay reported here can be adapted to screen other GPCRs that activate the Ca2+ signaling cascade.

In this work, a high-throughput, intracellular calcium fluorescence assay for 384-well plates to screen small molecule libraries on recombinant G protein-coupled receptors (GPCRs) is described. The target, the kinin receptor from the cattle fever tick, Rhipicephalus microplus, is expressed in CHO-K1 cells. This assay identifies agonists and antagonists using the same cells in one "dual-addition" assay.

Un saggio di fluorescenza del calcio "a doppia aggiunta" per lo screening ad alta produttività dei recettori accoppiati a proteine G ricombinanti

G protein-coupled receptors (GPCRs) represent the largest superfamily of receptors and are the targets of numerous human drugs. High-throughput screening ...

Biochimica

Using Enzyme-based Biosensors to Measure Tonic and Phasic Glutamate in Alzheimer's Mouse Models

Neurotransmitter disruption is often a key component of diseases of the central nervous system (CNS), playing a role in the pathology underlying Alzheimer's disease, Parkinson's disease, depression, and anxiety. Traditionally, microdialysis has been the most common (lauded) technique to examine neurotransmitter changes that occur in these disorders. But because microdialysis has the ability to measure slow 1-20 minute changes across large areas of tissue, it has the disadvantage of invasiveness, potentially destroying intrinsic connections within the brain and a slow sampling capability. A relatively newer technique, the microelectrode array (MEA), has numerous advantages for measuring specific neurotransmitter changes within discrete brain regions as they occur, making for a spatially and temporally precise approach. In addition, using MEAs is minimally invasive, allowing for measurement of neurotransmitter alterations in vivo. In our laboratory, we have been specifically interested in changes in the neurotransmitter, glutamate, related to Alzheimer's disease pathology. As such, the method described here has been used to assess potential hippocampal disruptions in glutamate in a transgenic mouse model of Alzheimer's disease. Briefly, the method used involves coating a multi-site microelectrode with an enzyme very selective for the neurotransmitter of interest and using self-referencing sites to subtract out background noise and interferents. After plating and calibration, the MEA can be constructed with a micropipette and lowered into the brain region of interest using a stereotaxic device. Here, the method described involves anesthetizing rTg(TauP301L)4510 mice and using a stereotaxic device to precisely target sub-regions (DG, CA1, and CA3) of the hippocampus.

Here, we describe the setup, software navigation, and data analysis for a spatially and temporally precise method of measuring tonic and phasic extracellular glutamate changes in vivo using enzyme-linked microelectrode arrays (MEA).

Utilizzando biosensori a base di enzimi misurare Tonic e Phasic glutammato in modelli murini di Alzheimer

Neurotransmitter disruption is often a key component of diseases of the central nervous system (CNS), playing a role in the pathology underlying ...

A High-content Assay for Monitoring AMPA Receptor Trafficking

Postsynaptic trafficking of receptors to and from the cell surface is an important mechanism by which neurons modulate their responsiveness to different stimuli. The &#945;-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, which are responsible for fast excitatory synaptic transmission in neurons, are trafficked to and from the postsynaptic surface to dynamically alter neuronal excitability. AMPA receptor trafficking is essential for synaptic plasticity and can be disrupted in neurological disease. However, prevalent approaches for quantifying receptor trafficking ignore entire receptor pools, are overly time- and labor-intensive, or potentially disrupt normal trafficking mechanisms and therefore complicate the interpretation of resulting data. We present a high-content assay for the quantification of both surface and internal AMPA receptor populations in cultured primary hippocampal neurons using dual fluorescent immunolabeling and a near-infrared fluorescent 96-well microplate scanner. This approach facilitates the rapid screening of bulk internalized and surface receptor densities while minimizing sample material. However, our method has limitations in obtaining single-cell resolution or conducting live cell imaging. Finally, this protocol may be amenable to other receptors and different cell types, provided proper adjustments and optimization.

Neuronal excitability can be modulated through a dynamic process of endo- and exocytosis of excitatory ionotropic glutamate receptors. Described here is an accessible, high-content assay for quantifying surface and internal receptor population pools.

Un'analisi ad alto contenuto per monitoraggio AMPA traffico recettoriale

Postsynaptic trafficking of receptors to and from the cell surface is an important mechanism by which neurons modulate their responsiveness to different ...

An Antibody Feeding Approach to Study Glutamate Receptor Trafficking in Dissociated Primary Hippocampal Cultures

Cellular responses to external stimuli heavily rely on the set of receptors expressed at the cell surface at a given moment. Accordingly, the population of surface-expressed receptors is constantly adapting and subject to strict mechanisms of regulation. The paradigmatic example and one of the most studied trafficking events in biology is the regulated control of the synaptic expression of glutamate receptors (GluRs). GluRs mediate the vast majority of excitatory neurotransmission in the central nervous system and control physiological activity-dependent functional and structural changes at the synaptic and neuronal levels (e.g., synaptic plasticity). Modifications in the number, location, and subunit composition of surface expressed GluRs deeply affect neuronal function and, in fact, alterations in these factors are associated with different neuropathies. Presented here is a method to study GluR trafficking in dissociated hippocampal primary neurons. An &#34;antibody-feeding&#34; approach is used to differentially visualize GluR populations expressed at the surface and internal membranes. By labeling surface receptors on live cells and fixing them at different times to allow for receptors endocytosis and/or recycling, these trafficking processes can be evaluated and selectively studied. This is a versatile protocol that can be used in combination with pharmacological approaches or overexpression of altered receptors to gain valuable information about stimuli and molecular mechanisms affecting GluR trafficking. Similarly, it can be easily adapted to study other receptors or surface expressed proteins.

This article presents a method to study glutamate receptor (GluR) trafficking in dissociated primary hippocampal cultures. Using an antibody-feeding approach to label endogenous or overexpressed receptors in combination with pharmacological approaches, this method allows for the identification of molecular mechanisms regulating GluR surface expression by modulating internalization or recycling processes.

Un approccio di alimentazione anticorpale per studiare il traffico di recettori del glutammato nelle culture ippocampali primarie dissociate

Cellular responses to external stimuli heavily rely on the set of receptors expressed at the cell surface at a given moment. Accordingly, the population ...

Single Synapse Indicators of Glutamate Release and Uptake in Acute Brain Slices from Normal and Huntington Mice

Synapses are highly compartmentalized functional units that operate independently on each other. In Huntington&#39;s disease (HD) and other neurodegenerative disorders, this independence might be compromised due to insufficient glutamate clearance and the resulting spill-in and spill-out effects. Altered astrocytic coverage of the presynaptic terminals and/or dendritic spines as well as a reduced size of glutamate transporter clusters at glutamate release sites have been implicated in the pathogenesis of diseases resulting in symptoms of dys-/hyperkinesia. However, the mechanisms leading to the dysfunction of glutamatergic synapses in HD are not well understood. Improving and applying synapse imaging we have obtained data shedding new light on the mechanisms impeding the initiation of movements. Here, we describe the principle elements of a relatively inexpensive approach to achieve single synapse resolution by using the new genetically encoded ultrafast glutamate sensor iGluu, wide-field optics, a scientific CMOS (sCMOS) camera, a 473 nm laser and a laser positioning system to evaluate the state of corticostriatal synapses in acute slices from age appropriate healthy or diseased mice. Glutamate transients were constructed from single or multiple pixels to obtain estimates of i) glutamate release based on the maximal elevation of the glutamate concentration [Glu] next to the active zone and ii) glutamate uptake as reflected in the time constant of decay (TauD) of the perisynaptic [Glu]. Differences in the resting bouton size and contrasting patterns of short-term plasticity served as criteria for the identification of corticostriatal terminals as belonging to the intratelencephalic (IT) or the pyramidal tract (PT) pathway. Using these methods, we discovered that in symptomatic HD mice ~40% of PT-type corticostriatal synapses exhibited insufficient glutamate clearance, suggesting that these synapses might be at risk to excitotoxic damage. The results underline the usefulness of TauD as a biomarker of dysfunctional synapses in Huntington mice with a hypokinetic phenotype.

We present a protocol to evaluate the balance between glutamate release and clearance at single corticostriatal glutamatergic synapses in acute slices from adult mice. This protocol uses the fluorescent sensor iGluu for glutamate detection, a sCMOS camera for signal acquisition and a device for focal laser illumination.

Indicatori di sinapsi singola di Soldamento Release e Uptake in Acute Brain Slices da Topi Normali e Huntington

Synapses are highly compartmentalized functional units that operate independently on each other. In Huntington&#39;s disease (HD) and other ...

Quantifying Spontaneous Ca2+ Fluxes and their Downstream Effects in Primary Mouse Midbrain Neurons

Parkinson&#8217;s disease (PD) is a devastating neurodegenerative disorder caused by the degeneration of dopaminergic (DA) neurons. Excessive Ca2+ influx due to the abnormal activation of glutamate receptors results in DA excitotoxicity and has been identified as an important mechanism for DA neuron loss. In this study, we isolate, dissociate, and culture midbrain neurons from the mouse ventral mesencephalon (VM) of ED14 mouse embryos. We then infect the long-term primary mouse midbrain cultures with an adeno-associated virus (AAV) expressing a genetically encoded calcium indicator, GCaMP6f under control of the human neuron-specific synapsin promoter, hSyn. Using live confocal imaging, we show that cultured mouse midbrain neurons display spontaneous Ca2+ fluxes detected by AAV-hSyn-GCaMP6f. Bath application of glutamate to midbrain cultures causes abnormal elevations in intracellular Ca2+ within neurons and this is accompanied by caspase-3 activation in DA neurons, as demonstrated by immunostaining. The techniques to identify glutamate-mediated apoptosis in primary mouse DA neurons have important applications for the high content screening of drugs that preserve DA neuron health.

Quantifying Spontaneous Ca2+ Fluxes and their Downstream Effects in Primary Mouse Midbrain Neurons

Here we present a protocol to measure in vitro Ca2+ fluxes in midbrain neurons and their downstream effects on caspase-3 using primary mouse midbrain cultures. This model can be employed to study pathophysiologic changes related to abnormal Ca2+ activity in midbrain neurons, and to screen novel therapeutics for anti-apoptotic properties.

Quantificare i flussispontanei di Ca 2 e i loro effetti a valle nei neuroni Midbrain del topo primario

Parkinson&#8217;s disease (PD) is a devastating neurodegenerative disorder caused by the degeneration of dopaminergic (DA) neurons. Excessive Ca2+ influx ...

One-channel Cell-attached Patch-clamp Recording

Ion channel proteins are universal devices for fast communication across biological membranes. The temporal signature of the ionic flux they generate depends on properties intrinsic to each channel protein as well as the mechanism by which it is generated and controlled and represents an important area of current research. Information about the operational dynamics of ion channel proteins can be obtained by observing long stretches of current produced by a single molecule. Described here is a protocol for obtaining one-channel cell-attached patch-clamp current recordings for a ligand gated ion channel, the NMDA receptor, expressed heterologously in HEK293 cells or natively in cortical neurons. Also provided are instructions on how to adapt the method to other ion channels of interest by presenting the example of the mechano-sensitive channel PIEZO1. This method can provide data regarding the channel&#8217;s conductance properties and the temporal sequence of open-closed conformations that make up the channel&#8217;s activation mechanism, thus helping to understand their functions in health and disease.

Described here is a procedure for obtaining long stretches of current recording from one ion channel with the cell-attached patch-clamp technique. This method allows for observing, in real time, the pattern of open-close channel conformations that underlie the biological signal. These data inform about channel properties in undisturbed biological membranes.

Un canale Cell-allegato patch-clamp registrazione

Ion channel proteins are universal devices for fast communication across biological membranes. The temporal signature of the ionic flux they generate ...

Biologia

Real-Time Fluorescent Measurement of Synaptic Functions in Models of Amyotrophic Lateral Sclerosis

Before neuronal degeneration, the cause of motor and cognitive deficits in patients with amyotrophic lateral sclerosis (ALS) and/or frontotemporal lobe dementia (FTLD) is dysfunction of communication between neurons and motor neurons and muscle. The underlying process of synaptic transmission involves membrane depolarization-dependent synaptic vesicle fusion and the release of neurotransmitters into the synapse. This process occurs through localized calcium influx into the presynaptic terminals where synaptic vesicles reside. Here, the protocol describes fluorescence-based live-imaging methodologies that reliably report depolarization-mediated synaptic vesicle exocytosis and presynaptic terminal calcium influx dynamics in cultured neurons.
Using a styryl dye that is incorporated into synaptic vesicle membranes, the synaptic vesicle release is elucidated. On the other hand, to study calcium entry, Gcamp6m is used, a genetically encoded fluorescent reporter. We employ high potassium chloride-mediated depolarization to mimic neuronal activity. To quantify synaptic vesicle exocytosis unambiguously, we measure the loss of normalized styryl dye fluorescence as a function of time. Under similar stimulation conditions, in the case of calcium influx, Gcamp6m fluorescence increases. Normalization and quantification of this fluorescence change are performed in a similar manner to the styryl dye protocol. These methods can be multiplexed with transfection-based overexpression of fluorescently tagged mutant proteins. These protocols have been extensively used to study synaptic dysfunction in models of FUS-ALS and C9ORF72-ALS, utilizing primary rodent cortical and motor neurons. These protocols easily allow for rapid screening of compounds that may improve neuronal communication. As such, these methods are valuable not only for the study of ALS but for all areas of neurodegenerative and developmental neuroscience research.

Two related methods are described to visualize subcellular events required for synaptic transmission. These protocols enable the real-time monitoring of the dynamics of presynaptic calcium influx and synaptic vesicle membrane fusion using live-cell imaging of in vitro cultured neurons.

Misurazione fluorescente in tempo reale delle funzioni sinaptiche in modelli di sclerosi laterale amiotrofica

Before neuronal degeneration, the cause of motor and cognitive deficits in patients with amyotrophic lateral sclerosis (ALS) and/or frontotemporal lobe ...