This work was supported by a grant from Agence Nationale de la Recherche (ChoAD). We are also grateful to the Fondation ICM (Institut du Cerveau et de la Moelle) for their financial support.

1. Calibration of the FCS Setup
<ol>
<li>Start the confocal microscope, lasers, computers, incubator for temperature and CO2 control.</li>
<li>Make sure the SPAD (Single Photon Avalanche Diode) is on and the fluorescence filter inside the SPAD is well suited to your sample. Check that the SPAD is synchronized in time. Beware to only start your FCS software once your SPAD settings are ready for acquisition.</li>
<li>Prepare a fresh solution of cholera toxin-Alexa488 diluted in PBS to reach a concentration of ...

<ol>
	<li>Brown, D. A., London, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functions+of+lipid+rafts+in+biological+membranes.">Functions of lipid rafts in biological membranes.</a> Annu. Rev. Cell Dev. Biol. 14, 111-136 (1998).</li><li>Simons, K., Gerl, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Revitalizing+membrane+rafts:+new+tools+and+insights.">Revitalizing membrane rafts: new tools and insights.</a> Nat. Rev. Mol. Cell Biol. 11, 688-699 (2010).</li><li>Simons, K., Ehehalt, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cholesterol,+lipid+rafts,+and+disease.">Cholesterol, lipid rafts, and disease.</a> J. Clin. Invest. 110, 597-603 (2002).</li><li>Munro, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipid+rafts:+elusive+or+illusive.">Lipid rafts: elusive or illusive.</a> Cell. , 115-377 (2003).</li><li>Shaw, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipid+rafts:+now+you+see+them,+now+you+don't.">Lipid rafts: now you see them, now you don't.</a> Nat. Immunol. 7, 1139-1142 (2006).</li><li>Pralle, A., Keller, P., Florin, E. L., Simons, K., Horber, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sphingolipid-cholesterol+rafts+diffuse+as+small+entities+in+the+plasma+membrane+of+mammalian+cells.">Sphingolipid-cholesterol rafts diffuse as small entities in the plasma membrane of mammalian cells.</a> J. Cell Biol. 148, 997-1008 (2000).</li><li>Brown, D. A., London, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+and+function+of+sphingolipid-+and+cholesterol-rich+membrane+rafts.">Structure and function of sphingolipid- and cholesterol-rich membrane rafts.</a> J. Biol Chem. 275, 17221-17224 (2000).</li><li>Sharma, P., Sabharanjak, S., Mayor, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endocytosis+of+lipid+rafts:+an+identity+crisis.">Endocytosis of lipid rafts: an identity crisis.</a> Semin. Cell Dev. Biol. 13, 205-214 (2002).</li><li>Kahya, N., Scherfeld, D., Bacia, K., Poolman, B., Schwille, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+lipid+mobility+of+raft-exhibiting+model+membranes+by+fluorescence+correlation+spectroscopy.">Probing lipid mobility of raft-exhibiting model membranes by fluorescence correlation spectroscopy.</a> J. Biol. Chem. 278, 28109-28115 (2003).</li><li>Bacia, K., Scherfeld, D., Kahya, N., Schwille, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+correlation+spectroscopy+relates+rafts+in+model+and+native+membranes.">Fluorescence correlation spectroscopy relates rafts in model and native membranes.</a> Biophys J. 87, 1034-1043 (2004).</li><li>Kim, S. A., Heinze, K. G., Schwille, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+correlation+spectroscopy+in+living+cells.">Fluorescence correlation spectroscopy in living cells.</a> Nat. Methods. 4, 963-973 (2007).</li><li>Marquer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Local+cholesterol+increase+triggers+amyloid+precursor+protein-Bace1+clustering+in+lipid+rafts+and+rapid+endocytosis.">Local cholesterol increase triggers amyloid precursor protein-Bace1 clustering in lipid rafts and rapid endocytosis.</a> FASEB J. 25, 1295-1305 (2011).</li><li>Tian, Y., Martinez, M. M., Pappas, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+correlation+spectroscopy:+a+review+of+biochemical+and+microfluidic+applications.">Fluorescence correlation spectroscopy: a review of biochemical and microfluidic applications.</a> Appl. Spectrosc. 65, 115A-124A (2011).</li><li>Haustein, E., Schwille, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+correlation+spectroscopy:+novel+variations+of+an+established+technique.">Fluorescence correlation spectroscopy: novel variations of an established technique.</a> Annu. Rev. Biophys. Biomol. Struct. 36, 151-169 (2007).</li><li>Ilien, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pirenzepine+promotes+the+dimerization+of+muscarinic+M1+receptors+through+a+three-step+binding+process.">Pirenzepine promotes the dimerization of muscarinic M1 receptors through a three-step binding process.</a> J. Biol. Chem. 284, 19533-19543 (2009).</li><li>Lieto, A. M., Cush, R. C., Thompson, N. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ligand-receptor+kinetics+measured+by+total+internal+reflection+with+fluorescence+correlation+spectroscopy.">Ligand-receptor kinetics measured by total internal reflection with fluorescence correlation spectroscopy.</a> Biophys. J. 85, 3294-3302 (2003).</li><li>Thompson, N. L., Burghardt, T. P., Axelrod, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+surface+dynamics+of+biomolecules+by+total+internal+reflection+fluorescence+with+photobleaching+recovery+or+correlation+spectroscopy.">Measuring surface dynamics of biomolecules by total internal reflection fluorescence with photobleaching recovery or correlation spectroscopy.</a> Biophys. J. 33, 435-454 (1981).</li><li>Thompson, N. L., Steele, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Total+internal+reflection+with+fluorescence+correlation+spectroscopy.">Total internal reflection with fluorescence correlation spectroscopy.</a> Nat. Protoc. 2, 878-890 (2007).</li><li>Eggeling, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+observation+of+the+nanoscale+dynamics+of+membrane+lipids+in+a+living+cell.">Direct observation of the nanoscale dynamics of membrane lipids in a living cell.</a> Nature. 457, 1159-1162 (2009).</li><li>Kolin, D. L., Wiseman, P. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+image+correlation+spectroscopy:+measuring+number+densities,+aggregation+states,+and+dynamics+of+fluorescently+labeled+macromolecules+in+cells.">Advances in image correlation spectroscopy: measuring number densities, aggregation states, and dynamics of fluorescently labeled macromolecules in cells.</a> Cell Biochem. Biophys. 49, 141-164 (2007).</li><li>Shvartsman, D. E., Kotler, M., Tall, R. D., Roth, M. G., Henis, Y. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differently+anchored+influenza+hemagglutinin+mutants+display+distinct+interaction+dynamics+with+mutual+rafts.">Differently anchored influenza hemagglutinin mutants display distinct interaction dynamics with mutual rafts.</a> J. Cell Biol. 163, 879-888 (2003).</li><li>White, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Holin+triggering+in+real+time.">Holin triggering in real time.</a> Proc. Natl. Acad. Sci. U.S.A. 108, 798-803 (2011).</li><li>Petersen, N. O., Hoddelius, P. L., Wiseman, P. W., Seger, O., Magnusson, K. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitation+of+membrane+receptor+distributions+by+image+correlation+spectroscopy:+concept+and+application.">Quantitation of membrane receptor distributions by image correlation spectroscopy: concept and application.</a> Biophys. J. 65, 1135-1146 (1993).</li><li>Hebert, B., Costantino, S., Wiseman, P. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatiotemporal+image+correlation+spectroscopy+(STICS)+theory,+verification,+and+application+to+protein+velocity+mapping+in+living+CHO+cells.">Spatiotemporal image correlation spectroscopy (STICS) theory, verification, and application to protein velocity mapping in living CHO cells.</a> Biophys. J. 88, 3601-3614 (2005).</li><li>Digman, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+fast+dynamics+in+solutions+and+cells+with+a+laser+scanning+microscope.">Measuring fast dynamics in solutions and cells with a laser scanning microscope.</a> Biophys. J. 89, 1317-1327 (2005).</li><li>Digman, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluctuation+correlation+spectroscopy+with+a+laser-scanning+microscope:+exploiting+the+hidden+time+structure.">Fluctuation correlation spectroscopy with a laser-scanning microscope: exploiting the hidden time structure.</a> Biophys. J. 88, L33-L36 (2005).</li><li>Nohe, A., Keating, E., Fivaz, M., van der Goot, F. G., Petersen, N. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+of+GPI-anchored+proteins+on+the+surface+of+living+cells.">Dynamics of GPI-anchored proteins on the surface of living cells.</a> Nanomedicine. 2, 1-7 (2006).</li><li>Semrau, S., Schmidt, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Particle+image+correlation+spectroscopy+(PICS):+retrieving+nanometer-scale+correlations+from+high-density+single-molecule+position+data.">Particle image correlation spectroscopy (PICS): retrieving nanometer-scale correlations from high-density single-molecule position data.</a> Biophys. J. 92, 613-621 (2007).</li><li>Bates, I. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Membrane+lateral+diffusion+and+capture+of+CFTR+within+transient+confinement+zones.">Membrane lateral diffusion and capture of CFTR within transient confinement zones.</a> Biophys. J. 91, 1046-1058 (2006).</li></ol>

No conflicts of interest declared.

The FCS method presented here enables a sensitive and rapid analysis of the lipid raft partitioning of fluorescent probes of interest in living cells. FCS combines the accuracy of localization of confocal microscopy with the sensitivity of single photon counting. The main difference between FCS and standard biochemical techniques is that FCS enables the absolute determination of the lipid rafts partition of the target and not the relative partition as is the case for DRMs isolation or co-patching.
<p class="jove_cont...

<table border="1">
 <tbody>
 <tr>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments </td>
 </tr>
 <tr>
 <td>Cholera toxin subunit B-Alexa 488</td>
 <td>Invitrogen</td>
 <td>C-34775</td>
 <td>MW (pentamer) = 57 kg/mol</td>
 </tr>
 <tr>
 <td>Confocal microscope</td>
 <td>Leica</td>
 <td>SP5</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Incubator for temperature and CO2 control</td>
 <td>Life imaging services</td>
 <td>The Cube and the Box</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>SPAD (Single Photon Avalanche Diode)</td>
 <td>MPD (Micro Photon Devices)</td>
 <td>PDM serie (100 &mu;m sensitive area) </td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>High pass 488 nm filter </td>
 <td>Semrock</td>
 <td>488 nm blocking edge BrightLine long-pass filter 
 Part # <a href="http://www.semrock.com/FilterDetails.aspx?id=FF01-488/LP-25" target="_blank">FF01-488/LP-25</a> </td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>FCS detection unit</td>
 <td>Picoquant</td>
 <td>Picoharp 300 module </td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Acquisition and auto-correlation software</td>
 <td>Picoquant</td>
 <td>SymPhoTime</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Fitting software</td>
 <td>OriginLab</td>
 <td>OriginPro8 </td>
 <td>&nbsp;</td>
 </tr>
 </tbody>
</table>

determination of lipid raft partitioning of fluorescently-tagged probes in living cells by fluorescence correlation spectroscopy (fcs)

In the past fifteen years the notion that cell membranes are not homogenous and rely on microdomains to exert their functions has become widely accepted. Lipid rafts are membrane microdomains enriched in cholesterol and sphingolipids. They play a role in cellular physiological processes such as signalling, and trafficking1,2 but are also thought to be key players in several diseases including viral or bacterial infections and neurodegenerative diseases3.
Yet their existence is still a matter of controversy4,5. Indeed, lipid raft size has been estimated to be around 20 nm6, far under the resolution limit of conventional microscopy (around 200 nm), thus precluding their direct imaging. Up to now, the main techniques used to assess the partition of proteins of interest inside lipid rafts were Detergent Resistant Membranes (DRMs) isolation and co-patching with antibodies. Though widely used because of their rather easy implementation, these techniques were prone to artefacts and thus criticized7,8. Technical improvements were therefore necessary to overcome these artefacts and to be able to probe lipid rafts partition in living cells.
Here we present a method for the sensitive analysis of lipid rafts partition of fluorescently-tagged proteins or lipids in the plasma membrane of living cells. This method, termed Fluorescence Correlation Spectroscopy (FCS), relies on the disparity in diffusion times of fluorescent probes located inside or outside of lipid rafts. In fact, as evidenced in both artificial membranes and cell cultures, probes would diffuse much faster outside than inside dense lipid rafts9,10. To determine diffusion times, minute fluorescence fluctuations are measured as a function of time in a focal volume (approximately 1 femtoliter), located at the plasma membrane of cells with a confocal microscope (Fig. 1). The auto-correlation curves can then be drawn from these fluctuations and fitted with appropriate mathematical diffusion models11.
FCS can be used to determine the lipid raft partitioning of various probes, as long as they are fluorescently tagged. Fluorescent tagging can be achieved by expression of fluorescent fusion proteins or by binding of fluorescent ligands. Moreover, FCS can be used not only in artificial membranes and cell lines but also in primary cultures, as described recently12. It can also be used to follow the dynamics of lipid raft partitioning after drug addition or membrane lipid composition change12.

Watch this Scientific Journal Video about Determination of Lipid Raft Partitioning of Fluorescently-tagged Probes in Living Cells by Fluorescence Correlation Spectroscopy FCS at JoVE.com

Determination of Lipid Raft Partitioning of Fluorescently-tagged Probes in Living Cells by Fluorescence Correlation Spectroscopy FCS

A technique to probe the lipid raft partitioning of fluorescent proteins at the plasma membrane of living cells is described. It takes advantage of the disparity in diffusion times of proteins located inside or outside of lipid rafts. Acquisition can be performed dynamically in control conditions or after drug addition.

Determination of Lipid Raft Partitioning of Fluorescently-tagged Probes in Living Cells by Fluorescence Correlation Spectroscopy (FCS)

In the past fifteen years the notion that cell membranes are not homogenous and rely on microdomains to exert their functions has become widely accepted. ...

determination-lipid-raft-partitioning-fluorescently-tagged-probes

Research

JoVE Journal

Biology

16.1K visualizações.  Hôpital de la Pitié-Salpêtrière. Uma técnica para sondar o particionamento jangada lipídico de proteínas fluorescentes na membrana plasmática de células vivas é descrito. Leva vantagem da disparidade em tempos de difusão de proteínas localizadas dentro ou fora de jangadas lipídicas. A aquisição pode ser realizada de forma dinâmica em condições de controlo ou após a adição da droga.