Este trabalho é apoiado pelo Escritório de Investigação e Desenvolvimento, Pesquisa Médica de Serviço, Departamento de Assuntos de Veteranos. Este estudo foi financiado por uma Prêmio Mérito VA Review (a MCL) e da Universidade do Tennessee, Centro de Ciências da Saúde Fundo de Investigação de Esclerose Múltipla.

1. Etiquetagem de anticorpos (Figura 1) <ol><li> Fazer NaHCO3 0,1 M de tampão: <ul type="circle"><li> 8,4 g de NaHCO3 </li><li> 29,2 g de NaCl </li><li> 1 litro de H 2 O </li></ul></li><li> Traga o tampão até um pH de 8,4 com esta solução (10,6 g de Na 2 CO 3, 29,2 g de NaCl, 1 litro de H 2 0). </li><li> Adicionar 35 ul de Atto550 NHS a 70 ul de anti-ul NaHCO hnRNPA1 e 500 3-tampão e girar durante 1 hora à temperatura ambiente. Após a rotação de uma hora, injectar a mistura num dialisador e dializar em 2 litros de PBS durante a noite. </li><li> No dia seguinte, concentrar os dialisados ​​Atto550 NHS anti-hnRNPA1 utilizando uma coluna de centrifugação (Amicon Ultra 0,5). </li><li> Após os Atto550 NHS rotulado anti-hnRNPA1 anticorpo foi concentrada, suspensa nano-amostra para determinar a concentração. </li></ol> 2. Transfecção de anticorpos (Figura 2) <ol><li> Semente 10 5 células / poço em 500 ul de DulbeccModificado o de Eagle Médium (DMEM/F12 +10% FBS 1% de antibiótico) num poço de deslizamento 8 24 horas antes da transfecção. Confluência de células deve ser, pelo menos, 70%. </li><li> Vinte e quatro horas após a sementeira, adicionar 2 ul de Ab-deliverin reagente para um tubo Eppendorf. </li><li> Em seguida, adicionar 2 ug de Atto550 NHS marcados anti-hnRNPA1 anticorpo (0,5 ug / uL) ao tubo de Eppendorf e mesmo incubar 10-15 min à temperatura ambiente. </li><li> Durante a incubação, aspirar meio e adicionar 394 uL de meio fresco de DMEM para as células. </li></ol> Nota: Adicionar 500 ul de DMEM para uma câmara de células intactas para actuar como um controlo. <ol start="5"><li> Após a incubação, adicionar 100 ul de DMEM com a mistura de anticorpos, misture pipetando para cima e para baixo, e adicionar as células em DMEM para um volume total de 500 ul. </li><li> Troque a mídia depois de 48 horas de entrega de anticorpos. </li></ol> Nota: O protocolo foi repetido com FITC Rigg como controlo positivo. 3. Imagens ao vivo e fixo para determinar a eficiência <ol><li> Células de imagem ao vivo às 48 horas usando os Cy3 filtro em um microscópio de fluorescência para a imagem dos transfectadas Atto550 NHS anticorpos marcados. </li><li> Depois de imagem ao vivo foi concluída, aspirar a mídia e as células de correção. </li><li> Depois de meios de aspiração, o tratamento de células com 0,4% de paraformaldeído durante 15 min à temperatura ambiente. Lave as células de 4 x 5 min cada com PBS. Em seguida, montar células com meios de montagem contendo DAPI reagente e lamela correção. Medir a eficiência de transfecção das células fixas com Axiovision software. Se Axiovision software não está na mão, basta contar os acontecimentos de sua imagem por resultados mão e ligue para cálculo em 3,7. Em alternativa, o software ImageJ podem ser usados ​​para estes cálculos. </li><li> Primeiro, use o &quot;Eventos&quot; medida para contar o número total de células em sua imagem de escolha com ampliação de 20x. </li><li> Em seguida, use o &quot;Eventos&quot; medida para contar as células que não eramtransfectadas com sucesso anticorpos na imagem mesma ampliação de 20x. </li><li> Para acessar os medidos &quot;Eventos&quot; em um formato estilo Excel, clique em &quot;Propriedades&quot;, clique na &quot;Medição&quot; guia, e clique para ver &quot;Como a Tabela&quot;. </li><li> Finalmente, use o seguinte cálculo para determinar a sua eficiência de transfecção, comparando os dois eventos previamente medidos: ((células Total - células não transfectadas) / total de células) x 100 = eficiência de transfecção. </li></ol> 4. Resultados representativos As imagens ao vivo de não transfectada (Figura 3A) em comparação com transfectadas (Figura 3B) neurónios revelam que a rotulagem dos anticorpos (vermelho ou verde, em cada figura) é claramente observado no interior das células (Figura 3B, C, D). Seguindo aspiração e lavagem com meios para remover os anticorpos entre ou aderentes à superfície das células, os anticorpos marcados são ainda presente dentro neurónios (Figura 3C e D).<html> Para o cálculo da eficiência de transfecção, utilizar o software para calcular Axiovision células totais comparados a células que não foram transfectadas com sucesso. Estes valores foram inseridos em uma fórmula de eficiência de transfecção para adquirir a eficiência de transfecção em percentagem do número total de células (Figura 4). <img alt="Figura 1" src="/files/ftp_upload/4154/4154fig1.jpg" /> Figura 1. Fluxograma dos procedimentos utilizados para os anticorpos de etiquetas com o 550 Atto NHS de éster seguida de etapas necessárias para concentrar os anticorpos marcados. <a href="http://www.jove.com/files/ftp_upload/4154/4154fig1large.jpg" target="_blank">para ver figura maior</a> . <img alt="Figura 2" src="/files/ftp_upload/4154/4154fig2.jpg" /> Figura 2. Diagrama de fluxo dos procedimentos utilizados para transfectar anticorpos marcados em células vivas em cultura.arge.jpg &quot;target =&quot; _blank &quot;&gt; Clique aqui para ver maior figura. <img alt="Figura 3" src="/files/ftp_upload/4154/4154fig3.jpg" /> Figura 3. Vivo imagens dos neurônios transfectadas 48 horas de transfecção seguinte. <img alt="Figura 4" src="/files/ftp_upload/4154/4154fig4.jpg" /> Figura 4. Corrigido e enxaguado imagens com acontecimentos contados a fim de determinar a eficiência de transfecção.

<ol>
	<li>Burkhardt, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epitope-specific+recognition+of+type+II+collagen+by+rheumatoid+arthritis+antibodies+is+shared+with+recognition+by+antibodies+that+are+arthritogenic+in+collagen-induced+arthritis+in+the+mouse.">Epitope-specific recognition of type II collagen by rheumatoid arthritis antibodies is shared with recognition by antibodies that are arthritogenic in collagen-induced arthritis in the mouse.</a> Arthritis Rheum. 46, 2339-2348 (2002).</li><li>Chester, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lambert-Eaton+syndrome+antibodies:+reaction+with+membranes+from+a+small+cell+lung+cancer+xenograft.">Lambert-Eaton syndrome antibodies: reaction with membranes from a small cell lung cancer xenograft.</a> J. Neuroimmunol. 18, 97-104 (1988).</li><li>Lee, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HTLV-1+induced+molecular+mimicry+in+neurological+disease.">HTLV-1 induced molecular mimicry in neurological disease.</a> Curr. Top Microbiol. Immunol. 29, 125-136 (2005).</li><li>Reeves, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systemic+lupus+erythematosus.+Antibodies+to+DNA,+DNA-binding+proteins,+and+histones.">Systemic lupus erythematosus. Antibodies to DNA, DNA-binding proteins, and histones.</a> Rheum. Dis. Clin. North Am. 20, 1-28 (1994).</li><li>Levin, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autoimmunity+due+to+molecular+mimicry+as+a+cause+of+neurological+disease.">Autoimmunity due to molecular mimicry as a cause of neurological disease.</a> Nat. Med. 8, 509-513 (2002).</li><li>Lee, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autoantibodies+that+recognize+functional+domains+of+hnRNPA1+implicate+molecular+mimicry+in+the+pathogenesis+of+neurological+disease.">Autoantibodies that recognize functional domains of hnRNPA1 implicate molecular mimicry in the pathogenesis of neurological disease.</a> Neurosci. Lett. 401, 188-193 (2006).</li><li>Kalume, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+mimicry:+cross-reactive+antibodies+from+patients+with+immune-mediated+neurologic+disease+inhibit+neuronal+firing.">Molecular mimicry: cross-reactive antibodies from patients with immune-mediated neurologic disease inhibit neuronal firing.</a> J. Neurosci. Res. 77, 82-89 (2004).</li><li>Levin, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cross-reactivity+between+immunodominant+human+T+lymphotropic+virus+type+I+tax+and+neurons:+implications+for+molecular+mimicry.">Cross-reactivity between immunodominant human T lymphotropic virus type I tax and neurons: implications for molecular mimicry.</a> J. Infect. Dis. 186, 1514-1517 (2002).</li><li>Lee, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+potential+link+between+autoimmunity+and+neurodegeneration+in+immune-mediated+neurological+disease.">A potential link between autoimmunity and neurodegeneration in immune-mediated neurological disease.</a> J. Neuroimmunol. 235, 56-69 (2011).</li><li>Smeenk, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antinuclear+antibodies:+cause+of+disease+or+caused+by+disease.">Antinuclear antibodies: cause of disease or caused by disease.</a> Rheumatology (Oxford). 39, 581-584 (2000).</li><li>Lee, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Post-translational+glycosylation+of+target+proteins+implicate+molecular+mimicry+in+the+pathogenesis+of+HTLV-1+associated+neurological+disease.">Post-translational glycosylation of target proteins implicate molecular mimicry in the pathogenesis of HTLV-1 associated neurological disease.</a> J. Neuroimmunol. 204, 140-148 (2008).</li><li>Reisinger, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serum-free+transfection+of+CHO+cells+with+chemically+defined+transfection+systems+and+investigation+of+their+potential+for+transient+and+stable+transfection.">Serum-free transfection of CHO cells with chemically defined transfection systems and investigation of their potential for transient and stable transfection.</a> Cytotechnology. 60, 115-123 (2009).</li><li>Weill, C. O., Biri, S., Erbacher, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cationic+lipid-mediated+intracellular+delivery+of+antibodies+into+live+cells.">Cationic lipid-mediated intracellular delivery of antibodies into live cells.</a> Biotechniques. 44, Pvii-Pxi (2008).</li><li>Radic, M. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterogeneous+nuclear+ribonucleoprotein+P2+is+an+autoantibody+target+in+mice+deficient+for+Mer,+Axl,+and+Tyro3+receptor+tyrosine+kinases.">Heterogeneous nuclear ribonucleoprotein P2 is an autoantibody target in mice deficient for Mer, Axl, and Tyro3 receptor tyrosine kinases.</a> J. Immunol. 176, 68-74 (2006).</li><li>Vincent, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Successful+'passive+transfer'+of+paraneoplastic+stiff+person+syndrome+with+antibodies+to+an+intracellular+antigen.">Successful 'passive transfer' of paraneoplastic stiff person syndrome with antibodies to an intracellular antigen.</a> Brain. 133, 3164-3165 (2010).</li><li>Vincent, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stiff,+twitchy+or+wobbly:+are+GAD+antibodies+pathogenic.">Stiff, twitchy or wobbly: are GAD antibodies pathogenic.</a> Brain. 131 (Pt 10), 2536-2537 (2008).</li><li>Magrys, A. <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+anti-alpha-enolase+autoantibodies+in+pathogenicity+of+autoimmune-mediated+retinopathy.">The role of anti-alpha-enolase autoantibodies in pathogenicity of autoimmune-mediated retinopathy.</a> J. Clin. Immunol. 27, 181-192 (2007).</li><li>Geis, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stiff+person+syndrome-associated+autoantibodies+to+amphiphysin+mediate+reduced+GABAergic+inhibition.">Stiff person syndrome-associated autoantibodies to amphiphysin mediate reduced GABAergic inhibition.</a> Brain. 133, 3166-3180 (2010).</li></ol>

Não há conflitos de interesse declarados.

A fim de testar hipóteses sobre moléculas específicas e sua expressão, genes e outros vectores normalmente são transfectados em células. O único aspecto deste processo é a capacidade de facilmente anticorpos para transfectar as células alvo. Realizamos este método em cinco experimentos em separado cada um em duplicatas. Resultados de eficiência de transfecção foram semelhantes entre todos os experimentos. É importante notar que o método permite a introdução de anticorpos para dentro da célula, sem alte...

<table border="1"><tbody><tr><td> Nome do reagente </td><td> Companhia </td><td> Número de Catálogo </td></tr><tr><td> Microscópio fluorescente AxioObserver A1 </td><td> Zeiss </td><td></td></tr><tr><td> Axiovision versão 4.2 </td><td> Zeiss </td><td></td></tr><tr><td> Anti-rhnRNPA1 </td><td> Abcam </td><td> Ab4791 </td></tr><tr><td> FITC anti-Rigg </td><td> OZ Biociências </td><td> AI20100 </td></tr><tr><td> Atto550 NHS éster </td><td> Sigma </td><td> 92835 </td></tr><tr><td> Ab-deliverin </td><td> OZ Biociências </td><td> AI20100 </td></tr><tr><td> DMEM/F12 +10% FBS antibióticos 1% </td><td> Gibco </td><td> 11320-033 </td></tr><tr><td> Poli-D-lisina-8 assim Slides Cultura </td><td> BD </td><td> 354632 </td></tr><tr><td> Multi-Purpose Rotator </td><td> Scientific Industries Inc </td><td> Modelo 151 </td></tr><tr><td> DAPI montar mídia </td><td> Millipore </td><td> S7113 </td></tr><tr><td> PBS </td><td> Ambion </td><td> 9626 </td></tr><tr><td> Dialisador </td><td> Thermo Fisher Scientific </td><td> 66380 </td></tr><tr><td> Amicon Ultra-0.5 </td><td> Millipore </td><td> UFC501096 </td></tr><tr><td> Paraformaldeído (solução a 4%) </td><td> Electron Microscopy Sciences </td><td></td></tr><tr><td> Nano-Drop </td><td> Thermo Fisher Scientific </td><td></td></tr></tbody></table>

antibody transfection into neurons as a tool to study disease pathogenesis

Anticorpos fornecem a capacidade de ter uma visão romance em vários eventos que ocorrem em sistemas vivos. A capacidade de produzir anticorpos altamente específicos para proteínas alvo tem permitido muito precisas questões biológicas a ser tratada. É importante notar que os anticorpos têm sido implicados na patogénese de várias doenças humanas, incluindo o lúpus eritematoso sistémico (SLE), artrite reumatóide (RA), as síndromes paraneoplásicas, a esclerose múltipla (MS) e o tipo de vírus T-linfotrópico humano 1 (HTLV-1) mielopatia associada ao / paraparesia espástica tropical (HAM / TSP) 1-9. Como anticorpos causam a doença é uma área de investigação em curso, e os dados sugerem que as interacções entre vários anticorpos e moléculas intracelulares resultados na inflamação, alterados celular, mensagens e apoptose 10. Tem sido demonstrado que os pacientes com EM e HAM / TSP produzir anticorpos para a proteína de ligação intracelular de proteínas RNA heterogéneo ribonuclear A1 (hnRNP A1) 3, 5-7, 9, 11. Dados recentes indicam que os anticorpos para tanto intra-neuronal e antigénios de superfície são patogénicas 3, 5-9, 11. Assim, um procedimento que permite o estudo de anticorpo intracelular: interações proteína daria grande insight sobre a patogênese da doença. Os genes são comumente transfectado em células primárias e linhas de células em cultura, no entanto a transfecção de anticorpos em células tem sido dificultada pela alteração da estrutura do anticorpo ou a eficiência de transfecção fraca 12. Outros métodos de transfecção incluem a transfecção com base em anticorpo lipossomas catiónicos (consistindo de DOTAP / DOPE) e polyethylenimines (PEI), ambas das quais resultou numa diminuição de 10 vezes na transfecção de anticorpos em comparação com os controlos 12. O método realizado em nosso estudo é semelhante à de lípidos catiónicos mediadas métodos e utiliza um mecanismo de base de lípidos de modo a formar complexos não covalentes com os anticorpos através electrostática e hidrinteracções ophobic 13. Utilizamos Ab-deliverin reagente, que é uma formulação de lípidos capaz de capturar os anticorpos não covalentes através de interacções electrostáticas e hidrofóbicas e entregando-os no interior das células. Assim químico e genético acoplamentos não são necessários para a entrega de anticorpos funcionais em células vivas. Este método permitiu-nos realizar várias anticorpo rastreamento e localização de proteínas experiências, bem como as análises das conseqüências moleculares de anticorpo intracelular: interações proteína 9. Neste protocolo, será mostrado como os anticorpos para transfectar-se em neurónios rápida, reprodutível e com um grau elevado de eficiência de transfecção. Como exemplo, iremos utilizar anticorpos anti-hnRNP A1 e anti-IgG. Para a quantificação da eficácia de transfecção fácil o uso do anti-hnRNP anticorpos marcados com A1 Atto-550-NHS e marcado com FITC de IgG. Atto550 SNS é um novo rótulo com absorção molecular alta e yi quânticaeld. Fonte de excitação e filtros fluorescentes para Atto550 são semelhantes a Cy3 (Ex. 556 Em. 578). Além disso, tem Atto550 fotoestabilidade elevada. Marcado com FITC de IgG foram utilizados como controlo para mostrar que este método é versátil e não dependente tingir. Esta abordagem e os dados que são gerados irão auxiliar na compreensão do papel que os anticorpos para antigénios alvo intracelulares podem desempenhar na patogénese de doenças humanas.

Watch this Scientific Journal Video about Antibody Transfection into Neurons as a Tool to Study Disease Pathogenesis at JoVE.com

Antibody Transfection into Neurons as a Tool to Study Disease Pathogenesis

Uma abordagem rápida para investigar as interacções e efeitos sobre os mecanismos moleculares relacionados com a presença de anticorpos em um ambiente intracelular é descrito. O método envolve a transfecção de anticorpos em células vivas utilizam uma formação complexo não-covalente com base em uma formulação de lípidos. A técnica é adaptável a linhas celulares imortalizadas, e células primárias.

Transfecção de anticorpos em neurônios como uma ferramenta para estudar a patogênese da doença

Antibodies provide the ability to gain novel insight into various events taking place in living systems.  The ability to produce highly specific ...

antibody-transfection-into-neurons-as-tool-to-study-disease

Research

JoVE Journal

Neuroscience

10.7K visualizações.  Veterans Administration Medical Center, Memphis, TN. Uma abordagem rápida para investigar as interacções e efeitos sobre os mecanismos moleculares relacionados com a presença de anticorpos em um ambiente intracelular é descrito. O método envolve a transfecção de anticorpos em células vivas utilizam uma formação complexo não-covalente com base em uma formulação de lípidos. A técnica é adaptável a linhas celulares imortalizadas, e células primárias.

Vídeo: Antibody Transfection into Neurons as a Tool to Study Disease Pathogenesis

Laser Capture Microdissection of Drosophila Peripheral Neurons

The dendritic arborization (da) neurons of the Drosophila peripheral nervous system (PNS) provide an excellent model system in which to investigate the molecular mechanisms underlying class-specific dendrite morphogenesis1,2. To facilitate molecular analyses of class-specific da neuron development, it is vital to obtain these cells in a pure population. Although a range of different cell, and tissue-specific RNA isolation techniques exist for Drosophila cells, including magnetic bead based cell purification3,4, Fluorescent Activated Cell Sorting (FACS)5-8, and RNA binding protein based strategies9, none of these methods can be readily utilized for isolating single or multiple class-specific Drosophila da neurons with a high degree of spatial precision. Laser Capture Microdissection (LCM) has emerged as an extremely powerful tool that can be used to isolate specific cell types from tissue sections with a high degree of spatial resolution and accuracy. RNA obtained from isolated cells can then be used for analyses including qRT-PCR and microarray expression profiling within a given cell type10-16. To date, LCM has not been widely applied in the analysis of Drosophila tissues and cells17,18, including da neurons at the third instar larval stage of development. 
Here we present our optimized protocol for isolation of Drosophila da neurons using the infrared (IR) class of LCM. This method allows for the capture of single, class-specific or multiple da neurons with high specificity and spatial resolution. Age-matched third instar larvae expressing a UAS-mCD8::GFP19 transgene under the control of either the class IV da neuron specific ppk-GAL420 driver or the pan-da neuron specific 21-7-GAL421 driver were used for these experiments. RNA obtained from the isolated da neurons is of very high quality and can be directly used for downstream applications, including qRT-PCR or microarray analyses. Furthermore, this LCM protocol can be readily adapted to capture other Drosophila cell types a various stages of development dependent upon the cell type specific, GAL4-driven expression pattern of GFP.

Laser Capture Microdissection of Drosophila Peripheral Neurons

In this video-article we present a method for isolating single or multiple Drosophila da neurons from third instar larvae using the infrared capture (IR) class of Laser Capture Microdissection (LCM). RNA obtained from the isolated neurons can be readily used for downstream applications including qRT-PCR or microarray analyses.

Laser Microdissecção Captura de Drosophila Neurônios periféricos

The dendritic arborization (da) neurons of the Drosophila peripheral nervous system (PNS) provide an excellent model system in which to investigate the ...

Neurociência

Cut-loading: A Useful Tool for Examining the Extent of Gap Junction Tracer Coupling Between Retinal Neurons

In addition to chemical synaptic transmission, neurons that are connected by gap junctions can also communicate rapidly via electrical synaptic transmission. Increasing evidence indicates that gap junctions not only permit electrical current flow and synchronous activity between interconnected or coupled cells, but that the strength or effectiveness of electrical communication between coupled cells can be modulated to a great extent1,2. In addition, the large internal diameter (~1.2 nm) of many gap junction channels permits not only electric current flow, but also the diffusion of intracellular signaling molecules and small metabolites between interconnected cells, so that gap junctions may also mediate metabolic and chemical communication. The strength of gap junctional communication between neurons and its modulation by neurotransmitters and other factors can be studied by simultaneously electrically recording from coupled cells and by determining the extent of diffusion of tracer molecules, which are gap junction permeable, but not membrane permeable, following iontophoretic injection into single cells. However, these procedures can be extremely difficult to perform on neurons with small somata in intact neural tissue.
Numerous studies on electrical synapses and the modulation of electrical communication have been conducted in the vertebrate retina, since each of the five retinal neuron types is electrically connected by gap junctions3,4. Increasing evidence has shown that the circadian (24-hour) clock in the retina and changes in light stimulation regulate gap junction coupling3-8. For example, recent work has demonstrated that the retinal circadian clock decreases gap junction coupling between rod and cone photoreceptor cells during the day by increasing dopamine D2 receptor activation, and dramatically increases rod-cone coupling at night by reducing D2 receptor activation7,8. However, not only are these studies extremely difficult to perform on neurons with small somata in intact neural retinal tissue, but it can be difficult to adequately control the illumination conditions during the electrophysiological study of single retinal neurons to avoid light-induced changes in gap junction conductance.
Here, we present a straightforward method of determining the extent of gap junction tracer coupling between retinal neurons under different illumination conditions and at different times of the day and night. This cut-loading technique is a modification of scrape loading9-12, which is based on dye loading and diffusion through open gap junction channels. Scrape loading works well in cultured cells, but not in thick slices such as intact retinas. The cut-loading technique has been used to study photoreceptor coupling in intact fish and mammalian retinas7, 8,13, and can be used to study coupling between other retinal neurons, as described here.

An easy and convenient method to determine the extent of gap junction tracer coupling between retinal neurons is described. This technique enables one to investigate the function of the electrical synapses between neurons in the intact retina under different illumination conditions and at different times of the day and night.

Cut-loading: Uma ferramenta útil para examinar a extensão da Gap Coupling Tracer junção entre neurônios da retina

In addition to chemical synaptic transmission, neurons that are connected by gap junctions can also communicate rapidly via electrical synaptic ...

Calcium Phosphate Transfection of Primary Hippocampal Neurons

Calcium phosphate precipitation is a convenient and economical method for transfection of cultured cells. With optimization, it is possible to use this method on hard-to-transfect cells like primary neurons. Here we describe our detailed protocol for calcium phosphate transfection of hippocampal neurons cocultured with astroglial cells.

Fosfato de cálcio transfecção de primário neurônios do hipocampo

Calcium phosphate precipitation is a convenient and economical method for transfection of cultured cells. With optimization, it is possible to use this ...

Real-Time Impedance-based Cell Analyzer as a Tool to Delineate Molecular Pathways Involved in Neurotoxicity and Neuroprotection in a Neuronal Cell Line

Many brain-related disorders have neuronal cell death involved in their pathophysiology. Improved in vitro models to study neuroprotective or neurotoxic effects of drugs and downstream pathways involved would help gain insight into the molecular mechanisms of neuroprotection/neurotoxicity and could potentially facilitate drug development. However, many existing in vitro toxicity assays have major limitations &#8211; most assess neurotoxicity and neuroprotection at a single time point, not allowing to observe the time-course and kinetics of the effect. Furthermore, the opportunity to collect information about downstream signaling pathways involved in neuroprotection in real-time would be of great importance. In the current protocol we describe the use of a real-time impedance-based cell analyzer to determine neuroprotective effects of serotonin 2A (5-HT2A) receptor agonists in a neuronal cell line under label-free and real-time conditions using impedance measurements. Furthermore, we demonstrate that inhibitors of second messenger pathways can be used to delineate downstream molecules involved in the neuroprotective effect. We also describe the utility of this technique to determine whether an effect on cell proliferation contributes to an observed neuroprotective effect. The system utilizes special microelectronic plates referred to as E-Plates which contain alternating gold microelectrode arrays on the bottom surface of the wells, serving as cell sensors. The impedance readout is modified by the number of adherent cells, cell viability, morphology, and adhesion. A dimensionless parameter called Cell Index is derived from the electrical impedance measurements and is used to represent the cell status. Overall, the real-time impedance-based cell analyzer allows for real-time, label-free assessment of neuroprotection and neurotoxicity, and the evaluation of second messenger pathways involvement, contributing to more detailed and high-throughput assessment of potential neuroprotective compounds in vitro, for selecting therapeutic candidates.

Improved in vitro neurotoxicity assays would aid the identification of new neuroprotective compounds. The utility of a real-time impedance-based cell analyzer to determine cytotoxicity and cytoprotection in neuronal cell lines and to delineate the involvement of second messenger pathways, thus gaining insight in the mechanism of neuroprotection is presented.

Analyzer celular baseado em impedância Real-Time como uma ferramenta para delinear vias moleculares envolvidas na neurotoxicidade e neuroproteção em uma linha de células neuronais

Many brain-related disorders have neuronal cell death involved in their pathophysiology. Improved in vitro models to study neuroprotective or neurotoxic ...

The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of the olfactory epithelium continuously give rise to new sensory neurons that extend their axons into the olfactory bulb, where they face the challenge to integrate into existing circuitry. Because of this particular feature, the olfactory system represents a unique opportunity to monitor axonal wiring and guidance, and to investigate synapse formation. Here we describe a procedure for in vivo labeling of sensory neurons and subsequent visualization of axons in the olfactory system of larvae of the amphibian Xenopus laevis. To stain sensory neurons in the olfactory organ we adopt the electroporation technique. In vivo electroporation is an established technique for delivering fluorophore-coupled dextrans or other macromolecules into living cells. Stained sensory neurons and their axonal processes can then be monitored in the living animal either using confocal laser-scanning or multiphoton microscopy. By reducing the number of labeled cells to few or single cells per animal, single axons can be tracked into the olfactory bulb and their morphological changes can be monitored over weeks by conducting series of in vivo time lapse imaging experiments. While the described protocol exemplifies the labeling and monitoring of olfactory sensory neurons, it can also be adopted to other cell types within the olfactory and other systems.

The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

We describe a protocol for in vivo labeling of olfactory sensory neurons by electroporation and subsequent confocal laser-scanning or multiphoton microscopy to visualize neuronal morphology and its development over time.

O Sistema Olfativo como um modelo para estudar os padrões de crescimento axonal e Morfologia<em&gt; In Vivo</em

The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of ...

Intramuscular Injections Along the Motor End Plates: A Minimally Invasive Approach to Shuttle Tracers Directly into Motor Neurons

Diseases affecting the integrity of spinal cord motor neurons are amongst the most debilitating neurological conditions. Over the last decades, the development of several animal models of these neuromuscular disorders has provided the scientific community with different therapeutic scenarios aimed at delaying or reversing the progression of these conditions. By taking advantage of the retrograde machinery of neurons, one of these approaches has been to target skeletal muscles in order to shuttle therapeutic genes into corresponding spinal cord motor neurons. Although once promising, the success of such gene delivery approach has been hampered by the sub-optimal number of transduced motor neurons it has so far shown to yield. Motor end plates (MEPs) are highly specialized regions on the skeletal musculature that are in direct synaptic contact to the spinal cord &#945; motor neurons. In this regard, it is important to note that, so far, the efforts to retrogradely transfer genes into motor neurons were made without reference to the location of the MEP region in the targeted muscles. Here, we describe a simple protocol 1) to reveal the exact location of the MEPs on the surface of skeletal muscles and 2) to use this information to guide the intramuscular delivery and subsequent optimal retrograde transport of retrograde tracers into motor neurons. We hope to utilize the results from these tracing experiments in further studies into investigating retrograde transport of therapeutic genes to spinal cord motor neurons through the targeting of MEPs.

The efficacy of intramuscular uptake and retrograde transport of molecules to corresponding motor neurons depends on the location of the injection sites with respect to the motor end plates (MEPs). Here, we describe how to locate MEPs on skeletal muscles to optimise retrograde transport of tracers into motor neurons.

Injecções intramusculares Ao longo das placas Motor End: uma abordagem minimamente invasiva para Shuttle Tracers Diretamente em Neurônios Motores

Diseases affecting the integrity of spinal cord motor neurons are amongst the most debilitating neurological conditions. Over the last decades, the ...

Stripe Assay to Study the Attractive or Repulsive Activity of a Protein Substrate Using Dissociated Hippocampal Neurons

Growing axons develop a highly motile structure at their tip, termed the growth cone. The growth cone contacts extracellular environmental cues to navigate axonal growth. Netrin, slit, semaphorin, and ephrins are known guidance molecules that can attract or repel axons upon binding to receptors and co-receptors on the axon. The activated receptors initiate various signaling molecules in the growth cone that alter the structure and movement of the neuron. Here, we describe the detailed protocol for a stripe assay to assess the ability of a guidance molecule to attract or repel neurons. In this method, dissociated hippocampal neurons from E15.5 mice are cultured on laminin-coated dishes processed with alternating stripes of ectodomain of fibronectin and leucine-rich transmembrane protein-2 (FLRT2) and control immunoglobulin G (IgG) fragment crystallizable region (Fc) protein. Both axons and cell bodies were strongly repelled from the FLRT2-coated stripe regions after 24 h of culture. Immunostaining with tau1 showed that ~90% of the neurons were distributed on the Fc-coated stripes compared to the FLRT2-Fc-coated stripes (~10%). This result indicates that FLRT2 has a strong repulsive effect on these neurons. This powerful method is applicable not only for primary cultured neurons but also for a variety of other cells, such as neuroblasts.

Axon guidance molecules regulate neuronal migration and targeted growth-cone navigation. We present a powerful method, the stripe assay, to assess the ability of guidance molecules to attract or repulse neurons. In this protocol, we demonstrate the stripe assay by showing FLRT2's ability to repel cultured hippocampal neurons.

Stripe Ensaio para estudar a atividade atração ou repulsão de um substrato de proteína utilizando dissociado neurônios do hipocampo

Growing axons develop a highly motile structure at their tip, termed the growth cone. The growth cone contacts extracellular environmental cues to ...

Organotypic Hippocampal Slice Cultures As a Model to Study Neuroprotection and Invasiveness of Tumor Cells

In organotypic hippocampal slice cultures (OHSC), the morphological and functional characteristics of both neurons and glial cells are well preserved. This model is suitable for addressing different research questions that involve studies on neuroprotection, electrophysiological experiments on neurons, neuronal networks or tumor invasion. The hippocampal architecture and neuronal activity in multisynaptic circuits are well conserved in OHSC, even though the slicing procedure itself initially lesions and leads to formation of a glial scar. The scar formation alters presumably the mechanical properties and diffusive behavior of small molecules, etc. Slices allow the monitoring of time dependent processes after brain injury without animal surgery, and studies on interactions between various brain-derived cell types, namely astrocytes, microglia and neurons under both physiological and pathological conditions. An ambivalent aspect of this model is the absence of blood flow and immune blood cells. During the progression of the neuronal injury, migrating immune cells from the blood play an important role. As those cells are missing in slices, the intrinsic processes in the culture may be observed without external interference. Moreover, in OHSC the composition of the medium-external environment is precisely controlled. A further advantage of this method is the lower number of sacrificed animals compared to standard preparations. Several OHSC can be obtained from one animal making simultaneous studies with multiple treatments in one animal possible. For these reasons, OHSC are well suited to analyze the effects of new protective therapeutics after tissue damage or during tumor invasion. 
The protocol presented here describes a preparation method of OHSC that allows generating highly reproducible, well preserved slices that can be used for a variety of experimental research, like neuroprotection or tumor invasion studies.

Organotypic hippocampal slice cultures (OHSC) represent an in vitro model that simulates the in vivo situation very well. Here we describe a vibratome-based improved slicing protocol to obtain high quality slices for use in assessing the neuroprotective potential of novel substances or the biological behavior of tumor cells.

Organotypic fatias Hippocampal culturas como um modelo para estudo neuroproteção e invasão de células tumorais

In organotypic hippocampal slice cultures (OHSC), the morphological and functional characteristics of both neurons and glial cells are well preserved. ...

Exogenous Administration of Microsomes-associated Alpha-synuclein Aggregates to Primary Neurons As a Powerful Cell Model of Fibrils Formation

For years, the inability of replicating formation of insoluble alpha-synuclein (&#945;S) inclusions in cell cultures has been a great limitation in the study of &#945;S aggregation in Parkinson&#39;s Disease (PD). Recently, the development of new animal models through the exogenous inoculation of brain extracts from diseased &#945;S transgenic mice or PD patients has given new hopes to the possibility of creating more adequate cell models of &#945;S aggregation. Unfortunately, when it comes to cells in cultures, administration of raw brain extracts has not proven as successful as in mice and the source of choice of exogenous aggregates is still in vitro preformed &#945;S fibrils.
We have developed a method to induce the formation of intracellular &#945;S inclusions in primary neurons through the exogenous administration of native microsomes-associated &#945;S aggregates, a highly toxic &#945;S species isolated from diseased areas of transgenic mice. This fraction of &#945;S aggregates that is associated with the microsomes vesicles, is efficiently internalized and induces the formation of intracellular inclusions positive for aggregated and phosphorylated &#945;S. Compared to in vitro-preformed fibrils which are made from recombinant &#945;S, our method is faster and guarantees that the pathogenic seeding is made with authentic &#945;S aggregates extracted from diseased animal models of PD, mimicking more closely the type of inclusions obtained in vivo. As a result, availability of tissues rich in &#945;S inclusions is mandatory.
We believe that this method will provide a versatile cell-based model to study the microscopic aspects of &#945;S aggregation and the related cellular pathophysiology in vivo and will be a starting point for the creation of more accurate and sophisticated cell paradigm of PD.

The goal of this protocol is to provide a cell-based system that replicates the formation of alpha-synuclein aggregates in vivo. Intracellular alpha-synuclein inclusions are seeded in primary neurons by the internalization and propagation of exogenous administered native microsomes-associated alpha-synuclein aggregates isolated from diseased alpha-synuclein transgenic mice.

Administração exógena de agregados de microssomas associados alfa-synuclein para os neurônios primários como um modelo de célula poderosos de formação de fibrilas

For years, the inability of replicating formation of insoluble alpha-synuclein (&#945;S) inclusions in cell cultures has been a great limitation in the ...

Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing neuronal dysfunction which eventually leads to cognitive decline. Hyperphosphorylated tau aggregates in the neuron are believed to cause most of the pathology associated with AD. These aggregates are assumed to be released into the extracellular compartment and taken up by adjacent healthy neurons where they induce further tau aggregation. This &#34;prion-like&#34; spreading can be interrupted by antibodies capable of binding and &#34;neutralizing&#34; extracellular tau aggregates as shown in preclinical mouse models of AD. One of the proposed mechanisms by which therapeutic antibodies reduce pathology is antibody-mediated uptake and clearance of pathological aggregated forms of tau by microglia. Here, we describe a quantitative cell-based assay to assess tau uptake by microglia. This assay uses the mouse microglial cell line BV-2, allows for high specificity, low variability and medium throughput. Data generated with this assay can contribute to a better characterization of anti-tau antibody effector functions.

Here we describe a cell-based assay to quantitatively assess tau uptake by microglia with the aim of creating an investigational tool to better characterize the mechanisms of action of anti-tau antibodies.

Baseada em célula de ensaio para estudar mediada por anticorpos Tau afastamento por Microglia

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing ...