Este trabalho foi financiado por concessões do Clifford Sra. Elder Branco Graham Dotado Fundo de Investigação e do NIH (AR059838) para CB, do NIH (AR052791, AR044387-ARRA, e NS063298) para LTT, e pelo Baylor College of Medicine Citometria e Cell Sorting Core com financiamento do NIH (NCRR S10RR024574, NIAID AI036211, e NCI P30CA125123). O conteúdo é da exclusiva responsabilidade dos autores e não representam, necessariamente, a posição oficial do NIH.

1. A coloração de células <ol><li> Prepare as células. As células devem ser usados ​​ao mesmo tempo crescendo ativamente (6-80 confluência%). Soro fome as células durante a noite, as células da placa-los em 0,1 milhões por poço em 0,5 mL meio isento de soro em uma placa de 24 poços e colocar na incubadora (37 ° C CO, 5% 2) por 30 min - 2 horas para se recuperar de tripsinização. </li><li> Misture os anticorpos primário e secundário. Mix (5 mL de anticorpos anti-GLUT4 primária com uma secundária de frango mL anti-IgG de cabra conjugado com AlexaFluor 488) x número de poços. Incubar por 10 minutos em temperatura ambiente, no escuro. </li><li> Prepare um estoque 2X de trabalho da insulina, diluindo-o em médio prazo. </li><li> Verifique se as células aderiram ou não. </li><li> Delicadamente adicionar 6 mL mix de anticorpos e 0,5 mL de seu estoque de insulina 2X trabalhar aos poços contendo as células. Evitar qualquer turbulência do meio. Incubar (37 ° C, 5% CO 2) por 30 minutos, no escuro. </li><li> Fixar as células, adicionando 0,5 mL de PBS + PFA 1% a cada poço, sem agitar as células. Incubar por 20 minutos em temperatura ambiente, no escuro. </li><li> Se suas células aderiram aos poços, levantar delicadamente os com um levantador de células. Transferência de células (1 total mL) em tubos que se encaixam na sua citômetro de fluxo e centrifugar para agregar as células. </li><li> Lave o pellet duas vezes com 1 mL de PBS e ressuspender em 0,4 mL de PBS + 1% PFA. Neste ponto, as células podem ser embrulhados em papel alumínio e armazenados na geladeira (4-8 ° C) ou levado para o citômetro de fluxo para aquisição de dados imediatos. </li></ol> 2. Aquisição de Dados <ol><li> Definir uma porta ampla em torno das células vivem na dispersão lateral (SSC) versus dispersão frente do painel (FCS). Use um tubo negativo (células não tratadas com insulina ou células &quot;manchado&quot; com um controle de isotipo) para definir o parâmetro FL1. Verifique se o seu pico é completamente no painel, não cortados no lado inferior. </li><li> Aquisição de dados de pelo menos 10 mil células por tubo. </li></ol> 3. Análise de Dados <ol><li> Desenhar uma porta em torno das células vivem no SSC FSC vs painel (Figura 1A). Plotar os histogramas de intensidade AlexaFluor 488 fluorescência versus número de células dentro do portão live-celular (Figura 1B). Você pode sobrepor histogramas diferentes de visualizar as diferenças, mas para a quantificação, determinar a intensidade média e mediana de fluorescência para cada população de células e usar esses números para o seu comparações (Figura 1C). </li><li> Normalizar os dados para o valor obtido na ausência de insulina, como mostrado nas Figuras 1C e 1D. </li></ol> 4. Resultados representante Em mioblastos isolado de um indivíduo saudável (sem resistência à insulina), a insulina induz a uma translocação dose-dependente de GLUT4 do citoplasma para a membrana plasmática (Figura 1, esquerda). Em contraste, a insulina não induz a translocação do GLUT4 para a membrana plasmática dos mioblastos isolado de um paciente com resistência à insulina (Figura 1, à direita). <img src="/files/ftp_upload/2429/2429fig1.jpg" alt="Figura 1" /> Figura 1. Exemplo de um experimento de coloração. Mioblastos foram isolados de um doador sem resistência à insulina (esquerda) e de um paciente com resistência à insulina (direita). A, SSC (Side Scatter) versus FCS parcela (para a frente de dispersão) com uma porta em torno da formação de células vivas. B, células gated em A, coradas com o anticorpo contra um epítopo externa do GLUT4, e deixou unstimulated (vermelho) ou estimuladas com insulina 1 nM (azul), 10 nm (laranja), ou 100 nM (verde). Para maior clareza a figura, só mostram dados sem e com 100 nM de insulina para as células com resistência à insulina. C, média intensidade de fluorescência (IMF) da histogramas mostrados na B foram normalizados para a IMF das células não estimuladas esquerdo (não insulina). D, Plots dos dados normalizados IFM da histogramas mostrados na B.

<ol>
	<li>Zhao, F. Q., Keating, A. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+properties+and+genomics+of+glucose+transporters.">Functional properties and genomics of glucose transporters.</a> Curr. Genomics. 8, 113-128 (2007).</li><li>Karnieli, E., Armoni, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptional+regulation+of+the+insulin-responsive+glucose+transporter+GLUT4+gene:+from+physiology+to+pathology.">Transcriptional regulation of the insulin-responsive glucose transporter GLUT4 gene: from physiology to pathology.</a> Am. J. Endocrinol. Metab. 295, 38-45 (2008).</li><li>Graham, T. E., Kahn, B. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue-specific+alterations+of+glucose+transport+and+molecular+mechanisms+of+intertissue+communication+in+obesity+and+type+2+diabetes.">Tissue-specific alterations of glucose transport and molecular mechanisms of intertissue communication in obesity and type 2 diabetes.</a> Horm. Metab. Res. 39, 717-721 (2007).</li><li>Alter, G., Malenfant, J. M., Altfeld, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD107a+as+a+functional+marker+for+the+identification+of+natural+killer+cell+activity.">CD107a as a functional marker for the identification of natural killer cell activity.</a> J. Immunol. Methods. 294, 15-22 (2004).</li><li>Vermes, I., Haanen, C., Steffens-Nakken, H., Reutellingsperger, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+assay+for+apoptosis.+Flow+cytometric+detection+of+phosphatidylserine+expression+on+early+apoptotic+cells+using+fluorescein+labeled+Annexin+V.">A novel assay for apoptosis. Flow cytometric detection of phosphatidylserine expression on early apoptotic cells using fluorescein labeled Annexin V.</a> J. Immunol. Methods. 184, 39-51 (1995).</li><li>Lugli, E., Roederer, M., Cossarizza, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Data+analysis+in+flow+cytometry:+the+future+just+started.">Data analysis in flow cytometry: the future just started.</a> Cytometry A. 77, 705-713 (2010).</li></ol>

Não há conflitos de interesse declarados.

Nós demonstramos uma técnica rápida para quantificar a translocação de GLUT4 do citoplasma para a membrana plasmática de células por citometria de fluxo. GLUT4 é apenas transitoriamente expressa na membrana plasmática das células e é endocytosed. Desde a anticorpos ligados permanecer ligada ao GLUT4, mesmo durante a endocitose, o sinal de fluorescência fornece a quantidade total de GLUT4 que foi exposto na membrana plasmática durante o período de incubação escolhido na presença de insulina. Esta técnica também pode ser aplicado para estudar a translocação de outras proteínas a partir de um compartimento intracelular para a membrana plasmática, desde um anticorpo boa direcionado para um epítopo externa da proteína de interesse está disponível. Por exemplo, um ensaio semelhante agora é comumente utilizado para avaliar a taxa de degranulação dos linfócitos T citotóxicos e linfócitos natural killer, medindo a translocação de CD107a à sua membrana plasmática 4,5. A translocação de fosfatidilserina do lado interno da membrana plasmática para o lado externo durante a apoptose ou necrose celular também pode ser detectada por citometria de fluxo, usando fluoróforo marcado anexina V 6. Além de rapidez do ensaio, citometria de fluxo apresenta a vantagem de permitir o estudo de translocação de proteínas para a membrana plasmática nas populações de células mistas. De fato, pode-se combinar coloração para marcadores subconjunto de células e para a proteína de interesse, seguido de aquisição de dados em um citômetro de fluxo de multi-laser 7. As quantidades de anticorpos enunciados no ponto 1.2 do protocolo são um ponto de partida, e recomendamos que o seu titular anticorpos com suas células de interesse para determinar a concentração de anticorpos mínimo que lhe dá um sinal máximo. Uma boa variedade de partida para o anticorpo anti-humano primário GLUT4 temos usado aqui seria mL 10-10 por tubo (ou seja, anticorpos 0,2-2 mg por tubo), cada tubo contendo não mais de 1 milhão de células. Para outros anticorpos primários, consulte as instruções do fornecedor. Normalização dos dados é necessária como autofluorescência de células irão variar de doadores para o doador e de experimento para experimento.

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		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Anti-human GLUT4 antibodies</td>
<td>&nbsp;</td>
<td>Santa Cruz Biotechnologies</td>
<td>sc-1606</td>
<td>Against an external epitope of GLUT4</td>
</tr>
<tr>
<td>Chicken anti-goat IgG conjugated to AlexaFluor 488</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>A-21467</td>
<td>&nbsp;</td>
<tr>
<td>Recombinant human insulin</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>I2643</td>
<td>&nbsp;</td>
<tr>
<td>Cell lifters</td>
<td>&nbsp;</td>
<td>VWR</td>
<td>29942-118</td>
<td>Cut to fit the wells</td>
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<tr>
<td>5 ml tubes for FACS</td>
<td>&nbsp;</td>
<td>VWR</td>
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quantitative measurement of glut4 translocation to the plasma membrane by flow cytometry

A glicose é a principal fonte de energia para o corpo, exigindo uma regulação constante de sua concentração no sangue. Liberação de insulina pelo pâncreas induz a absorção de glicose por tecidos sensíveis à insulina, principalmente o cérebro, músculo esquelético e adipócitos. Pacientes que sofrem de diabetes tipo 2 e / ou obesidade freqüentemente desenvolvem resistência à insulina e são incapazes de controlar sua homeostase da glicose. Novos insights sobre os mecanismos de resistência à insulina pode fornecer novas estratégias de tratamento para diabetes tipo 2. A família dos transportadores de glicose GLUT consiste de treze membros distribuídos em diferentes tecidos em todo o corpo 1. Transportador de glicose tipo 4 (GLUT4) é o transportador principais que medeia a captação de glicose pelos tecidos sensíveis à insulina, tais como o músculo esquelético. Após a ligação da insulina ao seu receptor, vesículas contendo GLUT4 translocate do citoplasma para a membrana plasmática, induzindo a captação de glicose. Reduziu a translocação do GLUT4 é uma das causas da resistência à insulina em diabetes tipo 2 2,3. A translocação de GLUT4 do citoplasma para a membrana plasmática pode ser visualizado por imunocitoquímica, utilizando fluoróforos GLUT4 anticorpos específicos. Aqui, descrevemos uma técnica para quantificar a quantidade total de GLUT4 translocação para a membrana plasmática das células durante um período escolhido, utilizando citometria de fluxo. Este protocolo é rápida (menos de 4 horas, incluindo a incubação com insulina) e permite a análise de tão poucos como 3.000 células ou mais de 1 milhão de células por condição em um único experimento. Ele se baseia em anticorpos anti-GLUT4 direcionado para um epítopo externa do transportador que se ligam a ele, logo que ela está exposta para o meio extracelular após a translocação para a membrana plasmática.

Watch this Scientific Journal Video about Quantitative Measurement of GLUT4 Translocation to the Plasma Membrane by Flow Cytometry at JoVE.com

Quantitative Measurement of GLUT4 Translocation to the Plasma Membrane by Flow Cytometry

Este protocolo descreve uma técnica rápida para quantificar a translocação do GLUT4 do citoplasma para a membrana plasmática de células por citometria de fluxo.

Medição quantitativa do GLUT4 translocação para a membrana plasmática por citometria de fluxo

Glucose is the main source of energy for the body, requiring constant regulation of its blood concentration. Insulin release by the pancreas induces ...

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26.3K visualizações.  Baylor College of Medicine. Este protocolo descreve uma técnica rápida para quantificar a translocação do GLUT4 do citoplasma para a membrana plasmática de células por citometria de fluxo.

Vídeo: Quantitative Measurement of GLUT4 Translocation to the Plasma Membrane by Flow Cytometry

Measuring Plasma Membrane Protein Endocytic Rates by Reversible Biotinylation

Plasma membrane proteins are a large, diverse group of proteins comprised of receptors, ion channels, transporters and pumps.  Activity of these proteins is responsible for a variety of key cellular events, including nutrient delivery, cellular excitability, and chemical signaling.  Many plasma membrane proteins are dynamically regulated by endocytic trafficking, which modulates protein function by altering protein surface expression.  The mechanisms that facilitate protein endocytosis are complex and are not fully understood for many membrane proteins.  In order to fully understand the mechanisms that control the endocytic trafficking of a given protein, it is critical that the protein s endocytic rate be precisely measured.  For many receptors, direct endocytic rate measurements are frequently achieved utilizing labeled receptor ligands.  However, for many classes of membrane proteins, such as transporters, pumps and ion channels, there is no convenient ligand that can be used to measure the endocytic rate.  In the present report, we describe a reversible biotinylation method that we employ to measure the dopamine transporter (DAT) endocytic rate.  This method provides a straightforward approach to measuring internalization rates, and can be easily employed for trafficking studies of most membrane proteins.

Regulated endocytosis governs the cell surface expression levels of the majority of membrane proteins. Here we utilize reducible, membrane impermeant biotinylation reagents to measure the endocytic rate of the dopamine transporter (DAT), a polytopic membrane protein. The method facilitates a straightforward approach to measuring the endocytic rate of most plasma membrane proteins.

Taxas de medição de plasma Proteína de membrana endocítica por Biotinilação reversível

Plasma membrane proteins are a large, diverse group of proteins comprised of receptors, ion channels, transporters and pumps.  Activity of these proteins ...

Biologia

IP-FCM:  Immunoprecipitation Detected by Flow Cytometry

Immunoprecipitation detected by flow cytometry (IP-FCM) is an efficient method for detecting and quantifying protein-protein interactions. The basic principle extends that of sandwich ELISA, wherein the captured primary analyte can be detected together with other molecules physically associated within multiprotein complexes. The procedure involves covalent coupling of polystyrene latex microbeads with immunoprecipitating monoclonal antibodies (mAb) specific for a protein of interest, incubating these beads with cell lysates, probing captured protein complexes with fluorochrome-conjugated probes, and analyzing bead-associated fluorescence by flow cytometry. IP-FCM is extremely sensitive, allows analysis of proteins in their native (non-denatured) state, and is amenable to either semi-quantitative or quantitative analysis. As additional advantages, IP-FCM requires no genetic engineering or specialized equipment, other than a flow cytometer, and it can be readily adapted for high-throughput applications.

The IP-FCM method is presented, which allows a sensitive, robust, biochemical assessment of native protein-protein interactions, without requiring genetic engineering or large sample sizes.

FCM-IP: Imunoprecipitação Detectado por citometria de fluxo

Immunoprecipitation detected by flow cytometry (IP-FCM) is an efficient method for detecting and quantifying protein-protein interactions. The basic ...

Flow Cytometry Purification of Mouse Meiotic Cells

The heterogeneous nature of cell types in the testis and the absence of meiotic cell culture models have been significant hurdles to the study of the unique differentiation programs that are manifest during meiosis. Two principal methods have been developed to purify, to varying degrees, various meiotic fractions from both adult and immature animals: elutriation or Staput (sedimentation) using BSA and/or percoll gradients. Both of these methods rely on cell size and density to separate meiotic cells1-5. Overall, except for few cell populations6, these protocols fail to yield sufficient purity of the numerous meiotic cell populations that are necessary for detailed molecular analyses. Moreover, with such methods usually one type of meiotic cells can be purified at a given time, which adds an extra level of complexity regarding the reproducibility and homogeneity when comparing meiotic cell samples.
Here, we describe a refined method that allows one to easily visualize, identify, and purify meiotic cells, from germ cells to round spermatids, using FACS combined with Hoechst 33342 staining7,8. This method provides an overall snapshot of the entire meiotic process and allows one to highly purify viable cells from most stage of meiosis. These purified cells can then be analyzed in detail for molecular changes that accompany progression through meiosis, for example changes in gene expression9,10and the dynamics of nucleosome occupancy at hotspots of meiotic recombination11.

An efficient method to obtain highly purified viable meiotic fractions from mouse testis is described, which combines a refined cell dissociation protocol with fluorescent activated cell sorting (FACS). This method takes advantage of differences in the DNA content and nuclear density of discrete meiotic fractions.

Purificação de Citometria de Fluxo de células de camundongo meiótica

The heterogeneous nature of cell types in the testis and the absence of meiotic cell culture models have been significant hurdles to the study of the ...

Mapping Molecular Diffusion in the Plasma Membrane by Multiple-Target Tracing (MTT)

Our goal is to obtain a comprehensive description of molecular processes occurring at cellular membranes in different biological functions. We aim at characterizing the complex organization and dynamics of the plasma membrane at single-molecule level, by developing analytic tools dedicated to Single-Particle Tracking (SPT) at high density: Multiple-Target Tracing (MTT)1. Single-molecule videomicroscopy, offering millisecond and nanometric resolution1-11, allows a detailed representation of membrane organization12-14 by accurately mapping descriptors such as cell receptors localization, mobility, confinement or interactions.
We revisited SPT, both experimentally and algorithmically. Experimental aspects included optimizing setup and cell labeling, with a particular emphasis on reaching the highest possible labeling density, in order to provide a dynamic snapshot of molecular dynamics as it occurs within the membrane. Algorithmic issues concerned each step used for rebuilding trajectories: peaks detection, estimation and reconnection, addressed by specific tools from image analysis15,16. Implementing deflation after detection allows rescuing peaks initially hidden by neighboring, stronger peaks. Of note, improving detection directly impacts reconnection, by reducing gaps within trajectories. Performances have been evaluated using Monte-Carlo simulations for various labeling density and noise values, which typically represent the two major limitations for parallel measurements at high spatiotemporal resolution.
The nanometric accuracy17 obtained for single molecules, using either successive on/off photoswitching or non-linear optics, can deliver exhaustive observations. This is the basis of nanoscopy methods17 such as STORM18, PALM19,20, RESOLFT21 or STED22,23, which may often require imaging fixed samples. The central task is the detection and estimation of diffraction-limited peaks emanating from single-molecules. Hence, providing adequate assumptions such as handling a constant positional accuracy instead of Brownian motion, MTT is straightforwardly suited for nanoscopic analyses. Furthermore, MTT can fundamentally be used at any scale: not only for molecules, but also for cells or animals, for instance. Hence, MTT is a powerful tracking algorithm that finds applications at molecular and cellular scales.

Mapping Molecular Diffusion in the Plasma Membrane by Multiple-Target Tracing MTT

Multiple-Target Tracing is a homemade algorithm developed for tracking individually labeled molecules within the plasma membrane of living cells. Efficiently detecting, estimating and tracing molecules over time at high-density provide a user-friendly, comprehensive tool to investigate nanoscale membrane dynamics.

Mapeamento de Difusão Molecular na membrana plasmática por Multiple-Target Tracing (MTT)

Our goal is to obtain a comprehensive description of molecular processes occurring at cellular membranes in different biological functions. We aim at ...

Optimized Staining and Proliferation Modeling Methods for Cell Division Monitoring using Cell Tracking Dyes

Fluorescent cell tracking dyes, in combination with flow and image cytometry, are powerful tools with which to study the interactions and fates of different cell types in vitro and in vivo.1-5 Although there are literally thousands of publications using such dyes, some of the most commonly encountered cell tracking applications include monitoring of:
<ol>
	<li>stem and progenitor cell quiescence, proliferation and/or differentiation6-8</li>
	<li>antigen-driven membrane transfer9 and/or precursor cell proliferation3,4,10-18 and</li>
	<li>immune regulatory and effector cell function1,18-21.</li>
</ol>
Commercially available cell tracking dyes vary widely in their chemistries and fluorescence properties but the great majority fall into one of two classes based on their mechanism of cell labeling. "Membrane dyes", typified by PKH26, are highly lipophilic dyes that partition stably but non-covalently into cell membranes1,2,11. "Protein dyes", typified by CFSE, are amino-reactive dyes that form stable covalent bonds with cell proteins4,16,18. Each class has its own advantages and limitations. The key to their successful use, particularly in multicolor studies where multiple dyes are used to track different cell types, is therefore to understand the critical issues enabling optimal use of each class2-4,16,18,24.
The protocols included here highlight three common causes of poor or variable results when using cell-tracking dyes. These are:
<ol>
	<li>Failure to achieve bright, uniform, reproducible labeling. This is a necessary starting point for any cell tracking study but requires attention to different variables when using membrane dyes than when using protein dyes or equilibrium binding reagents such as antibodies.</li>
	<li>Suboptimal fluorochrome combinations and/or failure to include critical compensation controls. Tracking dye fluorescence is typically 102 - 103 times brighter than antibody fluorescence. It is therefore essential to verify that the presence of tracking dye does not compromise the ability to detect other probes being used.</li>
	<li>Failure to obtain a good fit with peak modeling software. Such software allows quantitative comparison of proliferative responses across different populations or stimuli based on precursor frequency or other metrics. Obtaining a good fit, however, requires exclusion of dead/dying cells that can distort dye dilution profiles and matching of the assumptions underlying the model with characteristics of the observed dye dilution profile.</li>
</ol>
Examples given here illustrate how these variables can affect results when using membrane and/or protein dyes to monitor cell proliferation.

Successful use of cell tracking dyes to monitor immune cell function and proliferation involves several critical steps. We describe methods for: 1) obtaining bright, uniform, reproducible label-ing with membrane dyes; 2) selecting fluorochromes and data acquisition conditions; and 3) choosing a model to quantify cell proliferation based on dye dilution.

Optimizado coloração e Proliferação Métodos de Modelagem para Monitoramento Divisão Celular usando Corantes Rastreamento celulares

Fluorescent cell tracking dyes, in combination with flow and image cytometry, are powerful tools with which to study the interactions and fates of ...

Real-time Analyses of Retinol Transport by the Membrane Receptor of Plasma Retinol Binding Protein

Vitamin A is essential for vision and the growth/differentiation of almost all human organs. Plasma retinol binding protein (RBP) is the principle and specific carrier of vitamin A in the blood. Here we describe an optimized technique to produce and purify holo-RBP and two real-time monitoring techniques to study the transport of vitamin A by the high-affinity RBP receptor STRA6. The first technique makes it possible to produce a large quantity of high quality holo-RBP (100%-loaded with retinol) for vitamin A transport assays. High quality RBP is essential for functional assays because misfolded RBP releases vitamin A readily and bacterial contamination in RBP preparation can cause artifacts. Real-time monitoring techniques like electrophysiology have made critical contributions to the studies of membrane transport. The RBP receptor-mediated retinol transport has not been analyzed in real time until recently. The second technique described here is the real-time analysis of STRA6-catalyzed retinol release or loading. The third technique is real-time analysis of STRA6-catalyzed retinol transport from holo-RBP to cellular retinol binding protein I (CRBP-I). These techniques provide high sensitivity and resolution in revealing RBP receptor's vitamin A uptake mechanism.

Here we describe an optimized technique to produce high-quality vitamin A/RBP complex and two real-time monitoring techniques to study vitamin A transport by STRA6, the RBP receptor.

Em tempo real, análises de Transporte Retinol pelo receptor de membrana da proteína de Retinol Binding

Vitamin A is essential for vision and the growth/differentiation of almost all human organs.  Plasma retinol binding protein (RBP) is the principle and ...

Immunodetection of Outer Membrane Proteins by Flow Cytometry of Isolated Mitochondria

Methods to detect and monitor mitochondrial outer membrane protein components in animal tissues are vital to study mitochondrial physiology and pathophysiology. This protocol describes a technique where mitochondria isolated from rodent tissue are immunolabeled and analyzed by flow cytometry. Mitochondria are isolated from rodent spinal cords and subjected to a rapid enrichment step so as to remove myelin, a major contaminant of mitochondrial fractions prepared from nervous tissue. Isolated mitochondria are then labeled with an antibody of choice and a fluorescently conjugated secondary antibody. Analysis by flow cytometry verifies the relative purity of mitochondrial preparations by staining with a mitochondrial specific dye, followed by detection and quantification of immunolabeled protein. This technique is rapid, quantifiable and high-throughput, allowing for the analysis of hundreds of thousands of mitochondria per sample. It is applicable to assess novel proteins at the mitochondrial surface under normal physiological conditions as well as the proteins that may become mislocalized to this organelle during pathology. Importantly, this method can be coupled to fluorescent indicator dyes to report on certain activities of mitochondrial subpopulations and is feasible for mitochondria from the central nervous system (brain and spinal cord) as well as liver.

Described here is a method to detect and quantify mitochondrial outer membrane proteins by immunolabeling of mitochondria isolated from rodent tissue and analysis by flow cytometry. This method can be extended to assess functional aspects of mitochondrial subpopulations.

Imunodetecção de membrana externa proteínas por citometria de fluxo de mitocôndrias isoladas

Methods to detect and monitor mitochondrial outer membrane protein components in animal tissues are vital to study mitochondrial physiology and ...

Sensitive Measurement of Mitophagy by Flow Cytometry Using the pH-dependent Fluorescent Reporter mt-Keima

Mitophagy is a process of selective removal of damaged or unnecessary mitochondria using autophagy machinery. Close links have been found between defective mitophagy and various human diseases, including neurodegenerative diseases, cancer, and metabolic diseases. In addition, recent studies have shown that mitophagy is involved in normal cellular processes, such as differentiation and development. However, the precise role of and molecular mechanisms underlying mitophagy require further study. Therefore, it is critical to develop a robust and convenient method for measuring changes in mitophagy activity. Here, we describe a detailed protocol for quantitatively assessing mitophagy activity through flow cytometry using the mitochondria-targeted fluorescent protein Keima (mt-Keima). This flow cytometry assay can analyze mitophagy activity more rapidly and sensitively than conventional microscopy- or immunoblotting-based methods. This protocol can be applied to analyze mitophagy activity in various cell types.

Mitophagy, the selective degradation of mitochondria, has been implicated in mitochondrial homeostasis and is deregulated in various human diseases. However, convenient experimental methods for measuring mitophagy activity are very limited. Here, we provide a sensitive assay for measuring mitophagy activity using flow cytometry.

Medição de Mitophagy sensível pelo repórter fluorescentes Flow Cytometry usando o pH-dependente mt-Keima

Mitophagy is a process of selective removal of damaged or unnecessary mitochondria using autophagy machinery. Close links have been found between ...

High-throughput Measurement of Dictyostelium discoideum Macropinocytosis by Flow Cytometry

Large-scale non-specific fluid uptake by macropinocytosis is important for the proliferation of certain cancer cells, antigen sampling, host cell invasion and the spread of neurodegenerative diseases. The commonly used laboratory strains of the amoeba Dictyostelium discoideum have extremely high fluid uptake rates when grown in nutrient medium, over 90% of which is due to macropinocytosis. In addition, many of the known core components of mammalian macropinocytosis are also present, making it an excellent model system for studying macropinocytosis. Here, the standard technique to measure internalized fluid using fluorescent dextran as a label is adapted to a 96-well plate format, with the samples analyzed by flow cytometry using a high-throughput sampling (HTS) attachment.
Cells are fed non-quenchable fluorescent dextran for a pre-determined length of time, washed by immersion in ice-cold buffer and detached using 5 mM sodium azide, which also stops exocytosis. Cells in each well are then analyzed by flow cytometry. The method can also be adapted to measure membrane uptake and phagocytosis of fluorescent beads or bacteria.
This method was designed to allow measurement of fluid uptake by Dictyostelium in a high-throughput, labor and resource efficient manner. It allows simultaneous comparison of multiple strains (e.g. knockout mutants of a gene) and conditions (e.g. cells in different media or treated with different concentrations of inhibitor) in parallel and simplifies time-courses.

High-throughput Measurement of Dictyostelium discoideum Macropinocytosis by Flow Cytometry

Macropinocytosis, large-scale non-specific fluid uptake, is important in many areas of clinical biology including immunology, infection, cancer, and neurodegenerative diseases. Here, existing techniques have been adapted to allow high-throughput, single-cell resolution measurement of macropinocytosis in the macropinocytosis model organism Dictyostelium discoideum using flow cytometry.

Medição do elevado-throughput de Dictyostelium discoideum macropinocitose por citometria de fluxo

Large-scale non-specific fluid uptake by macropinocytosis is important for the proliferation of certain cancer cells, antigen sampling, host cell invasion ...

Detecting and Characterizing Protein Self-Assembly In Vivo by Flow Cytometry

Protein self-assembly governs protein function and compartmentalizes cellular processes in space and time. Current methods to study it suffer from low-sensitivity, indirect read-outs, limited throughput, and/or population-level rather than single-cell resolution. We designed a flow cytometry-based single methodology that addresses all of these limitations: Distributed Amphifluoric FRET or DAmFRET. DAmFRET detects and quantifies protein self-assemblies by sensitized emission FRET in vivo, enables deployment across model systems-from yeast to human cells-and achieves sensitive, single-cell, high-throughput read-outs irrespective of protein localization or solubility.

This article describes a FRET-based flow cytometry protocol to quantify protein self-assembly in both S. cerevisiae and HEK293T cells.