Name: rapid and robust analysis of cellular and molecular polarization induced by chemokine signaling
Uploaded: 2014-12-12T14:00:00.000+00:00
Duration: 10 min 3 s
Description: Watch this Scientific Journal Video about Rapid and Robust Analysis of Cellular and Molecular Polarization Induced by Chemokine Signaling at JoVE.com

Os autores agradecem grandemente Pierre Bourdoncle, Thomas Guilbert e Louise Rimbault da Facilidade Cochin Imaging. Este trabalho foi apoiado pelo Inserm, CNRS e Ligue Nationale contre le Câncer (Equipe labellisée).

1. Preparação de Linfócitos T <ol><li> Prepare primário do rato ou células T humanas, como descrito 10,11. </li><li> Cultivar células T humanas em meio RPMI completo com 10% de soro humano AB a uma densidade de 2 - 3 x 10 6 células / ml. NOTA: A utilização de soro fetal de vitelo (FCS) em vez de soro humano podem induzir a polarização espontânea de uma grande fracção de células T humanas em cultura. Manter essas células em cultura por 4-5 dias, e outro processo-los a qualquer momento durante esse período. </li><li> Manter as células T de rato em meio RPMI completo enriquecido com 10% de FCS a uma densidade celular semelhante. Utilizar imediatamente ou no dia seguinte, depois de uma cultura D / N a 37 ° C na presença de 10 ng / ml IL7. </li><li> Cultivar a linha de células T humanas CEM em meio RPMI completo enriquecido com 10% de FCS. </li></ol> 2. Chemokine Estimulação <ol><li> Lave 5 x 10 5 células por condição experimental em meio morno HBSS suplementado com 10 mM Hepes. Para algumas experiências, a co-transfecção de células T humanas primárias no dia anterior com 2 ug pmaxGFP e 8 ug pcDNA3.1 + (vector vazio, o controlo), PKCζ cinase morta, ou plasmídeos Par6 N-terminais. </li><li> Ressuspender o sedimento de células em meio HBSS morno-Hepes (0,3 ml usar x número de condições experimentais). </li><li> Distribuir as células em tubos de microcentrífuga de 1,5 ml. NOTA: Portanto, um tubo que corresponde a uma condição experimental único irá conter 5 x 10 5 células em 0,3 mL de meio HBSS-Hepes. Para algumas experiências, adicionar 500 nM Latrunculin A ou veículo (DMSO) e incubar as células durante 30 minutos antes da estimulação de quimiocina. </li><li> Adiciona-se 10 a 500 ng / ml ou CCL19 quimiocina CXCL12 em cada tubo. NOTA: Normalmente, usamos 10-200 quimocina ng / ml para células T humanas. As células CEM não expressam o receptor CCR7 que se liga CCL19. Portanto, células CEM apenas será capaz de responder a um estímulo CXCL12. Além disso, usar concentrações mais elevadas de quimiocinas (300-500 ng / ml) para polarizar as células T do mouse. </li><li> Virar os tubos várias vezes e incubar num banho de água a 37 C para 8 ° ou 10 min para as células T primárias ou CEM, respectivamente. </li><li> Parar o processo de polarização através da adição a cada tubo 0,3 ml de uma solução quente contendo 2% de paraformaldeído (PFA) e Hepes 10 mM em PBS. Virar os tubos e incubá-las a 37 ° C durante 5 min. </li></ol> 3. colorações <ol><li> Transferem-se as células a partir dos tubos de microcentrífuga para tubos de citometria de fluxo. </li><li> Encher os tubos com uma solução completamente RT contendo 1% de albumina de soro bovino (BSA), EDTA 0,5 mM e Hepes 10 mM em PBS. </li><li> Centrifugar os tubos a 460 xg por 4 min. </li><li> Descartar o sobrenadante e ressuspender as células em 100 ul de uma solução contendo RT 5% de FCS em PBS. </li><li> Adicionar 5 uL de FITC-anti-HLA-ABC, em cada tubo, eles vórtice, e incubar durante 30 min à temperatura ambiente, longe da luz. </li><li> Lave as células uma vez com PBS contendo 5% de FCS, umnd uma vez com apenas PBS. </li><li> À RT: adicionar 500 uL de 1% de PFA, incubar durante 10 min, em seguida, lavar as células com uma solução contendo 1% de BSA, EDTA 0,5 mM e HEPES 10 mM em PBS. </li><li> Rejeitar o sobrenadante, preencher completamente os tubos com uma solução de PBS contendo 0,2% de BSA, 0,1% de saponina, EDTA 0,5 mM e Hepes 10 mM (tampão de permeabilização). </li><li> Lavar as células duas vezes neste meio. </li><li> Virar os tubos para remover o meio e vortex-los para dissociar o sedimento celular. </li><li> Adicionar 0,25 g / ml TRITC-faloidina e / ou uma diluição 1: 100 de anticorpo anti-P-MTC a cada tubo, eles vórtice e incubar durante 30 min à temperatura ambiente. </li><li> Lavar as células com o tampão de permeabilização. Incubar com anticorpo secundário fluorescente, se necessário. </li><li> Ressuspender as células em 200 ul de PBS e transferi-las para tubos de microcentrífuga. NOTA: As células estão prontos para a aquisição. Alternativamente, ao mesmo tempo mantendo um volume máximo total de 200 ul por tubo, adicionar PFA concentrada para um final de 1%concentração, a fim de preservar as colorações se as células não estão a ser usados ​​no mesmo dia para processamento adicional. </li></ol> 4. Imagens de Aquisição e Análise <ol><li> Ligue o aparelho (ver Tabela de Specific Reagentes / Equipment) e deixá-lo calibrar-se de acordo com as instruções do fabricante. NOTA: O software INSPIRE foi usado com uma objetiva de 40X (0,75 NA). O software IDEIAS 3.0 foi utilizado para todas as quantificações relatados. </li><li> Preparar uma série de janelas de aquisição que podem ser salvos em um modelo para futuras experiências. Empate histogramas que quantifiquem os valores de gradiente RMS. Da população &quot;In Focus&quot;, selecionado no RMS histograma degradê, delimitar a população &quot;célula Single&quot; em um histograma da Area. Uma vez que o tubo de microcentrifugadora foi inserido na máquina, ajustar a potência do laser, portão em células individuais e adquirir 5.000 linfócitos T. </li><li> Nos Idéias suavesware, abra o arquivo de aquisição e criar um histograma que irá mostrar o valor do valor RMS gradiente de campo para imagens brilhantes (Canal 1) obtidos para cada célula individual. Desenhe um portão no histograma gradiente RMS que considera células exibindo RMS valor inclinação acima de 57. NOTA: O gradiente RMS permite ter em conta na análise apenas os linfócitos T que se encontram no plano focal. Determinou-se empiricamente que as células individuais que exibem um valor de gradiente de RMS são superiores a 57 no plano focal, e pode ser considerado com precisão. </li><li> No menu Análise / Máscaras, criar uma nova máscara, chamado Erode (M01,2) da máscara de morfologia nas imagens brightfield M01, erodidas de 2 pixels. Em seguida, na Análise / menu Recursos, crie um novo recurso do Espaço, calculado sobre a máscara Erode (M01,2). A partir das células selecionadas na porta anterior, abra um histograma mostrando a área de células usando essa máscara recém-criado. Máscaras a morfologia que estão disponíveis por: NOTAdefault são muito maiores do que o tamanho real da célula. Assim, é mais preciso que a corroer-se a 2 pixels. </li><li> Desenhe um portão nas células T individuais, excluindo as contas de calibração e detritos (pequena área) e as dobletos (grande área). Ajuste este portão em cada aquisição. NOTA: As variações no tamanho das células irá afectar a posição da porta. Como células T de rato são menores do que as células T humanas que são eles próprios menores que as células CEM, a área de cada tipo de célula será proporcional ao seu tamanho. </li><li> Considerando-se as células, em foco individuais que foram fechados com os passos anteriores, abrir um gráfico de pontos que consiste em bruto o pixel máximo na coloração de HLA-ABC (canal 2, o eixo x) em função do pixel em bruto Max a faloidina coloração (Channel 4, o eixo y). Criar um portão para excluir os eventos fluorescentes não coradas ou saturadas. Abra duas histogramas mostram a Raw Max Pixel para HLA-ABC (Canal 2) e phalloidin (Channel 4) colorações. </li><li> Na Análise / menu de Máscaras, createA nova máscara, chamado Erode (M02,2) da máscara morfologia das células HLA-ABC coradas (Canal 2), erodidas de 2 pixels. Em seguida, na Análise / menu Funções, criar uma nova característica que consiste no parâmetro circularidade, calculado sobre o Corrmoa (M02,2). NOTA: Este parâmetro mede o desvio da forma da célula a partir de um círculo. Portanto, uma célula T perfeitamente redonda terá um valor alto circularidade enquanto que as células polarizadas alongadas irá apresentar um baixo índice de circularidade. </li><li> Subsequentemente, criar um outro histograma que irá reportar os valores da característica circularidade das células previamente fechadas. Utilizar esta histograma para traçar directamente a distribuição de um indivíduo, a população de células em foco de acordo com o valor da circularidade para cada célula individual. </li><li> Olhando para o formato do histograma para células não estimuladas, para desenhar um portão células polarizadas, começando no valor circularidade mais baixo até ao valor limite circularidade onde a maioria das células não estimuladassão traçados. Olhe para a exibição de estatísticas para a percentagem de células polarizadas entre a população fechado (% fechado). NOTA: Criámos esta porta para valores de índice Circularidade abaixo 13. </li><li> De forma a olhar para a polarização da coloração de actina nas células, para traçar um histograma do detalhe brilhante valor Similaridade R3, comparando a coloração de HLA-ABC (canal 2) e a coloração com faloidina (Canal 4). NOTA: Quanto maior o valor desse recurso, o mais sobrepor as duas colorações são. </li><li> Utilizando a mesma estratégia gating como antes, traçar uma porta em que as células não-estimuladas para a coloração segregada que mostra a percentagem de células com coloração de actina polarizada. </li><li> Quando concluída, a percentagem de células que manifestam uma segregação na distribuição do MHC de Classe I e colorações faloidina, a percentagem de células polarizadas em conjunto com os valores médios dos índices Circularidade e similaridade de todas as células ± desvio padrão são mostrados na correspEstatísticas onding painéis. </li></ol>

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Os autores declaram que não têm interesses financeiros concorrentes.

Usando uma tecnologia recente de citometria de fluxo de imagem, uma estratégia de propagação rápida e informativo para analisar eventos celulares e moleculares induzidos por estimulação de quimiocina é apresentado. A partir de uma única experiência, pode obter-se dois tipos principais de informação: as alterações na morfologia celular induzida por estimulação de quimiocina e a distribuição subcelular de proteínas diferentes durante o processo de polarização. Curiosamente, os dados também é fornecid...

As quimiocinas são proteínas solúveis pequenos que atraem as células para locais especializados 1. Portanto, eles participam do posicionamento correto de células em tecidos, uma função crucial no desenvolvimento e fisiologia. O sistema imunológico não é excepção a esta regra, uma vez que conta com a ação de muitos tipos diferentes de células que agem em conjunto para montar uma resposta imune eficaz. Ao controlar o local específico de um tipo de célula imune em um determinado estado, as quimiocinas são pré-requerida antes de antigénios estranhos pode ser detectada e neutralizada. Para os linfócitos T, em particular, as quimiocinas se ligam a receptores específicos da superfície que, mediante acoplamento, provocam diversos sinais intracelulares (subida de cálcio, de fosforilação de ERK, activação as Rho GTPases, aumento da afinidade e integrinas alterações do citoesqueleto), que favorecem a motilidade de células T 2,3. Ao nível celular, pode-se observar alterações morfológicas induzidas por estimulação de quimiocinas.Essas mudanças nas formas celulares são especialmente dramática nas células T: células T em repouso têm uma morfologia Conta redonda semelhante ao viajar na corrente sanguínea. No entanto, a detecção da presença de quimiocinas em locais inflamatórios ou na proximidade dos órgãos linfóides vai alterar a forma das células T, que agora adoptar um típico &quot;mão-espelho&quot; morfologia que consiste de uma forma bipolar: um bordo de ataque na frente e um bordo de fuga, ou uropod, na parte de trás 4. Além disso, os componentes intracelulares pode separar em duas regiões opostas de uma célula T polarizada para sustentar a migração. Por exemplo, aumentos de filamentos de actina mediante polimerização de quimiocina estimulação 5 actina polimerizada e acumula-se na parte da frente de uma célula T polarizada 2. Por outro lado, diversas proteínas, tais como proteínas fosforiladas da família Ezrin-radixina-moesina (ERM) que ligam a membrana plasmática para o citoesqueleto de actina F cortical, re-localizar no uropod de polarizadaAs células T 6. Curiosamente, e outros mostraram que este processo de polarização é necessária para a migração de células T. Com efeito, qualquer tratamento que interfere com polarização irá inibir a motilidade celular. Por exemplo, a inibição da actividade dos membros da proteína atípica quinases C (PKC) da família, e PKCζ PKCι blocos t polarização celular e seu processo de digitalização migratório das células dendríticas 7. T polarização celular também é regulada por GTPases Rho. Mostrámos que a modulação da actividade da proteína RhoA por Fam65b recentemente descrito interfere com mudanças na morfologia das células T e a sua capacidade para migrar em um ensaio Transwell 6. Como polarização é um passo de pré-requisito para a motilidade celular, é, portanto, essencial para ser capaz de quantificar, como um visor principal de respostas de quimiocina. Alterações forma da célula foram previamente avaliados manualmente 8. No entanto, este tipo de quantificação é muito demorado, de modo que normalmente apenas algunsdezenas de células são tomadas em consideração. Aqui, um novo método é apresentado para quantificar rapidamente o grau de alterações de forma dos linfócitos T expostos ao estímulo de quimiocina. Um fluxo de citometria de tecnologia de imagem (ver Tabela de Reagentes Específico / Equipamento) é utilizada, a qual combina as vantagens de um citómetro de fluxo e um microscópio 9 para quantificar eficazmente a quantidade de células polarizadas em diferentes condições de estimulação de quimiocina. Para além da quantificação das alterações morfológicas que se pode medir de forma robusta com esta tecnologia, é também possível avaliar as alterações na localização subcelular de algumas proteínas mediante a sinalização da quimiocina.

<table><tbody><tr><td>RPMI</td><td>Gibco</td><td>61870-010</td><td></td></tr><tr><td>Human serum AB</td><td>PAA</td><td>C11-021</td><td>Pre-heat to inactivate the complement.</td></tr><tr><td>Fetal calf serum</td><td>PAN Biotech</td><td>P30-3300</td><td>Pre-heat to inactivate the complement.</td></tr><tr><td>Human T cell nucleofactor kit</td><td>Lonza</td><td>VCA-1002</td><td></td></tr><tr><td>Murine IL7</td><td>Peprotech</td><td>217-17</td><td></td></tr><tr><td>HBSS</td><td>Gibco</td><td>14025-050</td><td>Warm in 37 &amp;deg;C water bath before use.</td></tr><tr><td>Hepes</td><td>Gibco</td><td>15630-056</td><td></td></tr><tr><td>Murine CCL19</td><td>Peprotech</td><td>250-27B</td><td>Aliquots are thawed on ice before adding the chemokine to the cells.</td></tr><tr><td>Human CCL19</td><td>Peprotech</td><td>300-29B</td><td>Aliquots are thawed on ice before adding the chemokine to the cells.</td></tr><tr><td>Human CXCL12</td><td>Peprotech</td><td>300-28A</td><td>Aliquots are thawed on ice before adding the chemokine to the cells. This chemokine can also be used on mouse T cells.</td></tr><tr><td>PFA</td><td>Electron Microscopy Sciences</td><td>157-8-100</td><td>This is a 8% PFA solution in water. Mix volume to volume with 2x PBS to obtain a 4% PFA solution in PBS.</td></tr><tr><td>BSA</td><td>Sigma</td><td>A3059</td><td></td></tr><tr><td>Saponin</td><td>Fluka</td><td>84510</td><td></td></tr><tr><td>Alexa Fluor 594 phalloidin</td><td>Invitrogen</td><td>A12381</td><td></td></tr><tr><td>FITC-anti-HLA-ABC antibody</td><td>Beckman Coulter</td><td>IM1838</td><td>clone B9.12.1</td></tr><tr><td>Anti-P-ERM antibody</td><td>Cell Signaling Technology</td><td>3149P</td><td></td></tr><tr><td>ImageStream&lt;sup&gt;x&lt;/sup&gt; Mark II</td><td>Amnis</td><td></td><td></td></tr></tbody></table>

rapid and robust analysis of cellular and molecular polarization induced by chemokine signaling

As células respondem a quimioquinas estimulação por perder a sua forma redonda num processo chamado de polarização, e alterando a localização subcelular de muitas proteínas. Técnicas de imagem clássicos têm sido usados ​​para estudar esses fenômenos. No entanto, eles requerida a aquisição Manual de muitas células seguido de quantificação demorado da morfologia e a co-localização da coloração de dezenas de células. Aqui, um método rápido e eficaz é descrito para estudar estes fenómenos em amostras que consistem em vários milhares de células, utilizando um fluxo de imagens de citometria tecnologia que combina as vantagens de um microscópio com as de um citómetro. Usando os linfócitos T estimulados com CCL19 e coloração para moléculas de MHC de Classe I e a actina filamentosa, uma estratégia de propagação é apresentada para medir simultaneamente o grau de alterações de forma e a dimensão da co-localização de marcadores que são afectadas pela sinalização CCL19. Além disso, esta estratégia gating nos permitiu observoe a segregação de actina filamentosa (na frente) e fosforilada proteínas Ezrin-radixina-moesin (fosfo-ERM) (na parte traseira) em células T polarizadas após a estimulação CXCL12. Esta técnica também foi útil para observar o efeito de bloqueio em polarização de dois elementos diferentes: a inibição da polimerização da actina por um inibidor farmacológico e expressão de mutantes do Par6 / atípica via de sinalização PKC. Assim, a prova é mostrado que esta técnica é útil para analisar as duas alterações morfológicas e redistribuições de proteína.

O primeiro exemplo aqui escolhido se refere à utilização de linfócitos T primárias humanas estimuladas com CCL19. No entanto, a mesma estratégia pode ser usada com células T de rato primário, linhas de células T ou qualquer outro tipo de células responsivas à estimulação da quimiocina. A estratégia de gating aqui apresentado inclui uma série de janelas que selecionam os eventos temáticos, em seguida, as células individuais. Finalmente, o intervalo de intensidade de fluorescência é seguido aqui como um...

Watch this Scientific Journal Video about Rapid and Robust Analysis of Cellular and Molecular Polarization Induced by Chemokine Signaling at JoVE.com

Rapid and Robust Analysis of Cellular and Molecular Polarization Induced by Chemokine Signaling

Chemokine signaling elicits marked alterations of cellular morphology and some important redistributions of intracellular proteins. Here, a rapid and detailed protocol is provided to study these events.

Análise rápida e robusta de Celular e Molecular Polarização Induzida por Chemokine Signaling

Cells respond to chemokine stimulation by losing their round shape in a process called polarization, and by altering the subcellular localization of many ...

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8.0K visualizações.  Institut Cochin. Chemokine signaling elicits marked alterations of cellular morphology and some important redistributions of intracellular proteins. Here, a rapid and detailed protocol is provided to study these events.

Vídeo: Rapid and Robust Analysis of Cellular and Molecular Polarization Induced by Chemokine Signaling

Investigation of Macrophage Polarization Using Bone Marrow Derived Macrophages

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways.

Investigação de polarização de macrófagos Usando medula macrófagos derivados

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic ...

Imunologia e Infecção

Planar Gradient Diffusion System to Investigate Chemotaxis in a 3D Collagen Matrix

The importance of cell migration can be seen through the development of human life. When cells migrate, they generate forces and transfer these forces to their surrounding area, leading to cell movement and migration. In order to understand the mechanisms that can alter and/or affect cell migration, one can study these forces. In theory, understanding the fundamental mechanisms and forces underlying cell migration holds the promise of effective approaches for treating diseases and promoting cellular transplantation. Unfortunately, modern chemotaxis chambers that have been developed are usually restricted to two dimensions (2D) and have complex diffusion gradients that make the experiment difficult to interpret. To this end, we have developed, and describe in this paper, a direct-viewing chamber for chemotaxis studies, which allows one to overcome modern chemotaxis chamber obstacles able to measure cell forces and specific concentration within the chamber in a 3D environment to study cell 3D migration. More compelling, this approach allows one to successfully model diffusion through 3D collagen matrices and calculate the coefficient of diffusion of a chemoattractant through multiple different concentrations of collagen, while keeping the system simple and user friendly for traction force microscopy (TFM) and digital volume correlation (DVC) analysis.

Cell migration is an important part of human development and life. In order to understand the mechanisms that can alter cell migration, we present a planar gradient diffusion system to investigate chemotaxis in a 3D collagen matrix, which allows one to overcome modern diffusion chamber limitations of existing assays.

Gradiente planar do sistema de difusão para investigar Quimiotaxia numa Matriz de Colagénio 3D

The importance of cell migration can be seen through the development of human life. When cells migrate, they generate forces and transfer these forces to ...

Bioengenharia

Polydimethylsiloxane-polycarbonate Microfluidic Devices for Cell Migration Studies Under Perpendicular Chemical and Oxygen Gradients

This paper reports a microfluidic device made of polydimethylsiloxane (PDMS) with an embedded polycarbonate (PC) thin film to study cell migration under combinations of chemical and oxygen gradients. Both chemical and oxygen gradients can greatly affect cell migration in vivo; however, due to technical limitations, very little research has been performed to investigate their effects in vitro. The device developed in this research takes advantage of a series of serpentine-shaped channels to generate the desired chemical gradients and exploits a spatially confined chemical reaction method for oxygen gradient generation. The directions of the chemical and oxygen gradients are perpendicular to each other to enable straightforward migration result interpretation. In order to efficiently generate the oxygen gradients with minimal chemical consumption, the embedded PC thin film is utilized as a gas diffusion barrier. The developed microfluidic device can be actuated by syringe pumps and placed into a conventional cell incubator during cell migration experiments to allow for setup simplification and optimized cell culture conditions. In cell experiments, we used the device to study migrations of adenocarcinomic human alveolar basal epithelial cells, A549, under combinations of chemokine (stromal cell-derived factor, SDF-1&#945;) and oxygen gradients. The experimental results show that the device can stably generate perpendicular chemokine and oxygen gradients and is compatible with cells. The migration study results indicate that oxygen gradients may play an essential role in guiding cell migration, and cellular behavior under combinations of gradients cannot be predicted from those under single gradients. The device provides a powerful and practical tool for researchers to study interactions between chemical and oxygen gradients in cell culture, which can promote better cell migration studies in more in vivo-like microenvironments.

The control of chemical and oxygen gradients is essential for cell cultures. This paper reports a polydimethylsiloxane-polycarbonate (PDMS-PC) microfluidic device capable of reliably generating combinations of chemical and oxygen gradients for cell migration studies, which can be practically utilized in biological labs without sophisticated instrumentation.

Polidimetilsiloxano-policarbonato microfluídicos para celular Estudos Migratórios Sob Perpendicular Chemical e gradientes de oxigênio

This paper reports a microfluidic device made of polydimethylsiloxane (PDMS) with an embedded polycarbonate (PC) thin film to study cell migration under ...

3D Analysis of Multi-cellular Responses to Chemoattractant Gradients

Various limitations of 2D cell culture systems have sparked interest in 3D cell culture and analysis platforms, which would better mimic the spatial and chemical complexity of living tissues and mimic in vivo tissue functions. Recent advances in microfabrication technologies have facilitated the development of 3D in vitro environments in which cells can be integrated into a well-defined extracellular matrix (ECM) and a defined set of soluble or matrix associated biomolecules. However, technological barriers have limited their widespread use in research laboratories. Here, we describe a method to construct simple devices for 3D culture and experimentation with cells and multicellular organoids in 3D microenvironments with a defined chemoattractant gradient. We illustrate the use of this platform for analysis of the response of epithelial cells and organoids to gradients of growth factors, such as epidermal growth factor (EGF). EGF gradients were stable in the devices for several days leading to directed branch formation in breast organoids. This analysis allowed us to conclude that collective gradient sensing by groups of cells is more sensitive vs. single cells. We also describe the fabrication method, which does not require photolithography facilities nor advanced soft lithography techniques. This method will be helpful to study 3D cellular behaviors in the context of the analysis of development and pathological states, including cancer.

We describe a method to construct devices for 3D culture and experimentation with cells and multicellular organoids. This device allows analysis of cellular responses to soluble signals in 3D microenvironments with defined chemoattractant gradients. Organoids are better than single cells at detection of weak noisy inputs.

Análise 3D de respostas multicelulares a gradientes Quimioatrativos

Various limitations of 2D cell culture systems have sparked interest in 3D cell culture and analysis platforms, which would better mimic the spatial and ...

Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum

Many eukaryotic cells can detect gradients of chemical signals in their environments and migrate accordingly 1. This guided cell migration is referred as chemotaxis, which is essential for various cells to carry out their functions such as trafficking of immune cells and patterning of neuronal cells 2, 3. A large family of G-protein coupled receptors (GPCRs) detects variable small peptides, known as chemokines, to direct cell migration in vivo 4. The final goal of chemotaxis research is to understand how a GPCR machinery senses chemokine gradients and controls signaling events leading to chemotaxis. To this end, we use imaging techniques to monitor, in real time, spatiotemporal concentrations of chemoattractants, cell movement in a gradient of chemoattractant, GPCR mediated activation of heterotrimeric G-protein, and intracellular signaling events involved in chemotaxis of eukaryotic cells 5-8. The simple eukaryotic organism, Dictyostelium discoideum, displays chemotaxic behaviors that are similar to those of leukocytes, and D. discoideum is a key model system for studying eukaryotic chemotaxis. As free-living amoebae, D. discoideum cells divide in rich medium. Upon starvation, cells enter a developmental program in which they aggregate through cAMP-mediated chemotaxis to form multicullular structures. Many components involved in chemotaxis to cAMP have been identified in D. discoideum. The binding of cAMP to a GPCR (cAR1) induces dissociation of heterotrimeric G-proteins into G&gamma; and G&beta;&gamma; subunits 7, 9, 10. G&beta;&gamma; subunits activate Ras, which in turn activates PI3K, converting PIP2 into PIP3 on the cell membrane 11-13. PIP3 serve as binding sites for proteins with pleckstrin Homology (PH) domains, thus recruiting these proteins to the membrane 14, 15. Activation of cAR1 receptors also controls the membrane associations of PTEN, which dephosphorylates PIP3 to PIP2 16, 17. The molecular mechanisms are evolutionarily conserved in chemokine GPCR-mediated chemotaxis of human cells such as neutrophils 18. We present following methods for studying chemotaxis of D. discoideum cells. 1. Preparation of chemotactic component cells. 2. Imaging chemotaxis of cells in a cAMP gradient. 3. Monitoring a GPCR induced activation of heterotrimeric G-protein in single live cells. 4. Imaging chemoattractant-triggered dynamic PIP3 responses in single live cells in real time. Our developed imaging methods can be applied to study chemotaxis of human leukocytes.

Imaging G-protein Coupled Receptor GPCR-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum

Here, we describe detailed live cell imaging methods for investigating chemotaxis. We present fluorescence microscopic methods to monitor spatiotemporal dynamics of signaling events in migrating cells. Measurement of signaling events permits us to further understand how a GPCR-signaling network achieves gradient sensing of chemoattractants and controls directional migration of eukaryotic cells.

Receptor de imagem proteína G-Coupled (GPCR) mediada por eventos de sinalização que Quimiotaxia de Controle de Dictyostelium discoideum</em

Many eukaryotic cells can detect gradients of chemical signals in their environments and migrate accordingly 1.  This guided cell migration is referred as ...

Biologia

Measurement of Cellular Chemotaxis with ECIS/Taxis

Cellular movement in response to external stimuli is fundamental to many cellular processes including wound healing, inflammation and the response to infection. A common method to measure chemotaxis is the Boyden chamber assay, in which cells and chemoattractant are separated by a porous membrane. As cells migrate through the membrane toward the chemoattractant, they adhere to the underside of the membrane, or fall into the underlying media, and are subsequently stained and visually counted 1. In this method, cells are exposed to a steep and transient chemoattractant gradient, which is thought to be a poor representation of gradients found in tissues 2.
Another assay system, the under-agarose chemotaxis assay, 3, 4 measures cell movement across a solid substrate in a thin aqueous film that forms under the agarose layer. The gradient that develops in the agarose is shallow and is thought to be an appropriate representation of naturally occurring gradients. Chemotaxis can be evaluated by microscopic imaging of the distance traveled. Both the Boyden chamber assay and the under-agarose assay are usually configured as endpoint assays.
The automated ECIS/Taxis system combines the under-agarose approach with Electric Cell-substrate Impedance Sensing (ECIS) 5, 6. In this assay, target electrodes are located in each of 8 chambers. A large counter-electrode runs through each of the 8 chambers (Figure 2). Each chamber is filled with agarose and two small wells are the cut in the agarose on either side of the target electrode. One well is filled with the test cell population, while the other holds the sources of diffusing chemoattractant (Figure 3). Current passed through the system can be used to determine the change in resistance that occurs as cells pass over the target electrode. Cells on the target electrode increase the resistance of the system 6. In addition, rapid fluctuations in the resistance represent changes in the interactions of cells with the electrode surface and are indicative of ongoing cellular shape changes. The ECIS/Taxis system can measure movement of the cell population in real-time over extended periods of time, but is also sensitive enough to detect the arrival of a single cell at the target electrode. 
Dictyostelium discoidium is known to migrate in the presence of a folate gradient 7, 8 and its chemotactic response can be accurately measured by ECIS/Taxis 9. Leukocyte chemotaxis, in response to SDF1&alpha; and to chemotaxis antagonists has also been measured with ECIS/Taxis 10, 11. An example of the leukocyte response to SDF1&alpha; is shown in Figure 1.

The ECIS/Taxis system is an automated, real-time assay that measures cellular chemotaxis. In this assay, cells move beneath a layer of agarose to arrive at a target electrode. Cellular movement is measured by the onset of resistance to AC current 0.

Medição de Quimiotaxia celulares com ECIS / Taxis

Cellular movement in response to external stimuli is fundamental to many cellular processes including wound healing, inflammation and the response to ...

Assessment of Lymphocyte Migration in an Ex Vivo Transmigration System

Herein, we present an efficient method that can be executed with basic laboratory skills and materials to assess lymphocyte chemokinetic movement in an ex vivo transmigration system. Group 2 innate lymphoid cells (ILC2) and CD4+ T helper cells were isolated from spleens and lungs of chicken egg ovalbumin (OVA)-challenged BALB/c mice. We confirmed the expression of CCR4 on both CD4+ T cells and ILC2, comparatively. CCL17 and CCL22 are the known ligands for CCR4; therefore, using this ex vivo transmigration method we examined CCL17- and CCL22-induced movement of CCR4+ lymphocytes. To establish chemokine gradients, CCL17 and CCL22 were placed in the bottom chamber of the transmigration system. Isolated lymphocytes were then added to top chambers and over a 48 h period the lymphocytes actively migrated through 3 &#181;m pores towards the chemokine in the bottom chamber. This is an effective system for determining the chemokinetics of lymphocytes, but, understandably, does not mimic the complexities found in the in vivo organ microenvironments. This is one limitation of the method that can be overcome by the addition of in situ imaging of the organ and lymphocytes under study. In contrast, the advantage of this method is that is can be performed by an entry-level technician at a much more cost-effective rate than live imaging. As therapeutic compounds become available to enhance migration, as in the case of tumor infiltrating cytotoxic immune cells, or to inhibit migration, perhaps in the case of autoimmune diseases where immunopathology is of concern, this method can be used as a screening tool. In general, the method is effective if the chemokine of interest is consistently generating chemokinetics at a statistically higher level than the media control. In such cases, the degree of inhibition/enhancement by a given compound can be determined as well.

In this protocol, lymphocytes are placed in the top chamber of a transmigration system, separated from the bottom chamber by a porous membrane. Chemokine is added to the bottom chamber, which induces active migration along a chemokine gradient. After 48 h, lymphocytes are counted in both chambers to quantitate transmigration.

Avaliação da migração do linfócito em um sistema de transmigração ex vivo

Herein, we present an efficient method that can be executed with basic laboratory skills and materials to assess lymphocyte chemokinetic movement in an ex ...

Time-lapse Imaging of Mouse Macrophage Chemotaxis

Chemotaxis is receptor-mediated guidance of cells along a chemical gradient, whereas chemokinesis is the stimulation of random cell motility by a chemical. Chemokinesis and chemotaxis are fundamental for the mobilization and deployment of immune cells. For example, chemokines (chemotactic cytokines) can rapidly recruit circulating neutrophils and monocytes to extravascular sites of inflammation. Chemoattractant receptors belong to the large family of G protein-coupled receptors. How chemoattractant (i.e., ligand) gradients direct cell migration via G protein-coupled receptor signaling is not yet fully understood. In the field of immunology, neutrophils are popular model cells for studying chemotaxis in vitro. Here we describe a real-time two-dimensional (2D) chemotaxis assay tailored for mouse resident macrophages, which have traditionally been more difficult to study. Macrophages move at a slow pace of ~1 &#181;m/min on a 2D surface and are less well suited for point-source migration assays (e.g., migration towards the tip of a micropipette filled with chemoattractant) than neutrophils or Dictyostelium discoideum, which move an order of magnitude faster. Widely used Transwell assays are useful for studying the chemotactic activity of different substances, but do not provide information on cell morphology, velocity, or chemotactic navigation. Here we describe a time-lapse microscopy-based macrophage chemotaxis assay that allows quantification of cell velocity and chemotactic efficiency and provides a platform to delineate the transducers, signal pathways, and effectors of chemotaxis.

Here we describe methods using time-lapse, phase-contrast microscopy to image mouse resident peritoneal macrophages in a chemotactic complement C5a gradient. The protocols can be extended to other immune cells.

Imagem em lapso de tempo de Quimioterapia de Macrophage mouse

Chemotaxis is receptor-mediated guidance of cells along a chemical gradient, whereas chemokinesis is the stimulation of random cell motility by a ...

Imaging G Protein-coupled Receptor-mediated Chemotaxis and its Signaling Events in Neutrophil-like HL60 Cells

Eukaryotic cells sense and move towards a chemoattractant gradient, a cellular process referred as chemotaxis. Chemotaxis plays critical roles in many physiological processes, such as embryogenesis, neuron patterning, metastasis of cancer cells, recruitment of neutrophils to sites of inflammation, and the development of the model organism Dictyostelium discoideum. Eukaryotic cells sense chemo-attractants using G protein-coupled receptors. Visual chemotaxis assays are essential for a better understanding of how eukaryotic cells control chemoattractant-mediated directional cell migration. Here, we describe detailed methods for: 1) real-time, high-resolution monitoring of multiple chemotaxis assays, and 2) simultaneously visualizing the chemoattractant gradient and the spatiotemporal dynamics of signaling events in neutrophil-like HL60 cells.

Visual chemotaxis assays are essential for a better understanding of how eukaryotic cells control chemoattractant-mediated directional cell migration. Here, we describe detailed methods for: 1) real-time, high-resolution monitoring of multiple chemotaxis assays, and 2) simultaneously visualizing the chemoattractant gradient and the spatiotemporal dynamics of signaling events in neutrophil-like HL60 cells.

Imagiologia G protein-coupled receptor mediada por quimiotaxia e seus eventos de sinalização em células de HL60 de Neutrófilos-like

Eukaryotic cells sense and move towards a chemoattractant gradient, a cellular process referred as chemotaxis. Chemotaxis plays critical roles in many ...

Assessment of Dictyostelium discoideum Response to Acute Mechanical Stimulation

Chemotaxis, or migration up a gradient of a chemoattractant, is the best understood mode of directed migration. Studies using social amoeba Dictyostelium discoideum revealed that a complex signal transduction network of parallel pathways amplifies the response to chemoattractants, and leads to biased actin polymerization and protrusion of a pseudopod in the direction of a gradient. In contrast, molecular mechanisms driving other types of directed migration, for example, due to exposure to shear flow or electric fields, are not known. Many regulators of chemotaxis exhibit localization at the leading or lagging edge of a migrating cell, as well as show transient changes in localization or activation following global stimulation with a chemoattractant. To understand the molecular mechanisms of other types of directed migration we developed a method that allows examination of cellular response to acute mechanical stimulation based on brief (2 - 5 s) exposure to shear flow. This stimulation can be delivered in a channel while imaging cells expressing fluorescently-labeled biosensors to examine individual cell behavior. Additionally, cell population can be stimulated in a plate, lysed, and immunoblotted using antibodies that recognize active versions of proteins of interest. By combining both assays, one can examine a wide array of molecules activated by changes in subcellular localization and/or phosphorylation. Using this method we determined that acute mechanical stimulation triggers activation of the chemotactic signal transduction and actin cytoskeleton networks. The ability to examine cellular responses to acute mechanical stimulation is important for understanding the initiating events necessary for shear flow-induced motility. This approach also provides a tool for studying the chemotactic signal transduction network without the confounding influence of the chemoattractant receptor.

Assessment of Dictyostelium discoideum Response to Acute Mechanical Stimulation

Here we describe methods for assessing cellular response to acute mechanical stimulation. In the microscopy-based assay, we examine localization of fluorescently-labeled biosensors following brief stimulation with shear flow. We also test activation of various proteins of interest in response to acute mechanical stimulation biochemically.

Avaliação de Dictyostelium discoideum resposta à estimulação mecânica aguda

Chemotaxis, or migration up a gradient of a chemoattractant, is the best understood mode of directed migration. Studies using social amoeba Dictyostelium ...