Name: studying proteolysis of cyclin b at the single cell level in whole cell populations
Uploaded: 2012-09-17T13:00:00
Description: Watch this Scientific Journal Video about Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations at JoVE.com

We are grateful to S. Taylor for providing the pLPCX-Histone H2-GFP plasmid. We thank R. Mertelsmann for continuous support. This work was supported by the Deutsche Forschungsgemeinschaft.

1. Seeding of U2OS-based Cyclin B-SNAP Reporter Cells (Clone 11 Cells 6) on Microscope Chamber Slides
<ol>
	<li>Trypsinize subconfluent SNAP reporter cells that were allowed to grow asynchronously in log phase for at least 48 hr.</li>
	<li>Working with 8 well microscope chambers (constant distribution of cells).</li>
</ol>
For seeding of cells onto 8 well microscope chambers at a constant distribution across the entire surface of the microscope chamber, centrifuge 10,000 cells and res...

<ol>
	<li>Musacchio, A., Salmon, E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+spindle-assembly+checkpoint+in+space+and+time.">The spindle-assembly checkpoint in space and time.</a> Nat. Rev. Mol. Cell Biol. 8, 379-393 (2007).</li><li>Nasmyth, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Segregating+sister+genomes:+the+molecular+biology+of+chromosome+separation.">Segregating sister genomes: the molecular biology of chromosome separation.</a> Science. 297, 559-565 (2002).</li><li>Cahill, D. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mutations+of+mitotic+checkpoint+genes+in+human+cancers.">Mutations of mitotic checkpoint genes in human cancers.</a> Nature. 392, 300-303 (1998).</li><li>Lengauer, C., Kinzler, K. W., Vogelstein, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+instabilities+in+human+cancers.">Genetic instabilities in human cancers.</a> Nature. 396, 643-649 (1998).</li><li>Fletcher, D. A., Mullins, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+mechanics+and+the+cytoskeleton.">Cell mechanics and the cytoskeleton.</a> Nature. 463, 485-4892 (2010).</li><li>Schnerch, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+APC/C+activity+in+the+presence+of+chromosomal+misalignment+in+unperturbed+cell+populations.">Monitoring APC/C activity in the presence of chromosomal misalignment in unperturbed cell populations.</a> Cell Cycle. 11, (2012).</li><li>Keppler, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+general+method+for+the+covalent+labeling+of+fusion+proteins+with+small+molecules+in+vivo.">A general method for the covalent labeling of fusion proteins with small molecules in vivo.</a> Nat. Biotechnol. 21, 86-869 (2003).</li><li>Jansen, L. E., Black, B. E., Foltz, D. R., Cleveland, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Propagation+of+centromeric+chromatin+requires+exit+from+mitosis.">Propagation of centromeric chromatin requires exit from mitosis.</a> J. Cell. Biol. 176, 795-805 (2007).</li><li>Malureanu, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cdc20+hypomorphic+mice+fail+to+counteract+de+novo+synthesis+of+cyclin+B1+in+mitosis.">Cdc20 hypomorphic mice fail to counteract de novo synthesis of cyclin B1 in mitosis.</a> J. Cell Biol. 191, 313-329 (2010).</li><li>Mena, A. L., Lam, E. W., Chatterjee, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sustained+spindle-assembly+checkpoint+response+requires+de+novo+transcription+and+translation+of+cyclin+B1.">Sustained spindle-assembly checkpoint response requires de novo transcription and translation of cyclin B1.</a> PLoS One. 5, (2010).</li><li>Wolthuis, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cdc20+and+Cks+direct+the+spindle+checkpoint-independent+destruction+of+cyclin.">Cdc20 and Cks direct the spindle checkpoint-independent destruction of cyclin.</a> A. Mol. Cell. 30, 290-302 (2008).</li></ol>

We present here a live-cell imaging-based approach facilitating the simultaneous monitoring of cyclin B proteolysis and chromosome alignment. This approach allows the study of mitotic control in unperturbed cell populations at the single cell level. Cyclin B degradation curves facilitate direct insights into the activity of the APC/C and thus indirectly reflect the status of the SAC 6.
This approach, even though established based on the Scan^R software, can easily be reproduced on ...

<table border="1">
	<tbody>
		<tr>
			<td>Name of product</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>Comments (optional)</td>
		</tr>
		<tr>
			<td>Reporter cell line</td>
			<td>generated in-house as described 6</td>
			<td>clone 11 reporter cells 
			(U2Os-based cyclin B-SNAP expressing cells)</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Retroviral cyclin B-SNAP expression vector</td>
			<td>generated in-house as described 6</td>
			<td>pLNCX2-cyclin B mut5-SNAP</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Phenolred-free DMEM</td>
			<td>Gibco</td>
			<td>21063-029</td>
			<td>Supplementation with FCS, sodium pyruvate, penicillin/strepto-mycin required</td>
		</tr>
		<tr>
			<td>SNAP-Cell TMR-Star</td>
			<td>New England Biolabs</td>
			<td>S9105S</td>
			<td>Stock solution 400 &mu;M in DMSO</td>
		</tr>
		<tr>
			<td>Special Opstics Plate, 96 well</td>
			<td>Costar</td>
			<td>3720</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&mu;-Slide 8 well, ibiTreat</td>
			<td>Ibidi</td>
			<td>80826</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Microscopy unit</td>
			<td>Olympus</td>
			<td>IX-81 inverse microscope with climate chamber</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Objective</td>
			<td>Olympus</td>
			<td>UPLSAPO 20x objective (N.A. 0.75)</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Acquisition software</td>
			<td>Olympus</td>
			<td>Scan^R Acquisition software (v.2.2.09)</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Analysis software</td>
			<td>Olympus</td>
			<td>Scan^R Analysis software (v.1.2.0.6)</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

studying proteolysis of cyclin b at the single cell level in whole cell populations

Equal distribution of chromosomes between the two daughter cells during cell division is a prerequisite for guaranteeing genetic stability 1. Inaccuracies during chromosome separation are a hallmark of malignancy and associated with progressive disease 2-4. The spindle assembly checkpoint (SAC) is a mitotic surveillance mechanism that holds back cells at metaphase until every single chromosome has established a stable bipolar attachment to the mitotic spindle1. The SAC exerts its function by interference with the activating APC/C subunit Cdc20 to block proteolysis of securin and cyclin B and thus chromosome separation and mitotic exit. Improper attachment of chromosomes prevents silencing of SAC signaling and causes continued inhibition of APC/CCdc20 until the problem is solved to avoid chromosome missegregation, aneuploidy and malignant growths1.
Most studies that addressed the influence of improper chromosomal attachment on APC/C-dependent proteolysis took advantage of spindle disruption using depolymerizing or microtubule-stabilizing drugs to interfere with chromosomal attachment to microtubules. Since interference with microtubule kinetics can affect the transport and localization of critical regulators, these procedures bear a risk of inducing artificial effects 5.
To study how the SAC interferes with APC/C-dependent proteolysis of cyclin B during mitosis in unperturbed cell populations, we established a histone H2-GFP-based system which allowed the simultaneous monitoring of metaphase alignment of mitotic chromosomes and proteolysis of cyclin B 6.
To depict proteolytic profiles, we generated a chimeric cyclin B reporter molecule with a C-terminal SNAP moiety 6 (Figure 1). In a self-labeling reaction, the SNAP-moiety is able to form covalent bonds with alkylguanine-carriers (SNAP substrate) 7,8 (Figure 1). SNAP substrate molecules are readily available and carry a broad spectrum of different fluorochromes. Chimeric cyclin B-SNAP molecules become labeled upon addition of the membrane-permeable SNAP substrate to the growth medium 7 (Figure 1). Following the labeling reaction, the cyclin B-SNAP fluorescence intensity drops in a pulse-chase reaction-like manner and fluorescence intensities reflect levels of cyclin B degradation 6 (Figure 1). Our system facilitates the monitoring of mitotic APC/C-dependent proteolysis in large numbers of cells (or several cell populations) in parallel. Thereby, the system may be a valuable tool to identify agents/small molecules that are able to interfere with proteolytic activity at the metaphase to anaphase transition. Moreover, as synthesis of cyclin B during mitosis has recently been suggested as an important mechanism in fostering a mitotic block in mice and humans by keeping cyclin B expression levels stable 9,10, this system enabled us to analyze cyclin B proteolysis as one element of a balanced equilibrium 6.

Watch this Scientific Journal Video about Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations at JoVE.com

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations

Metaphase to anaphase transition is triggered through anaphase-promoting complex (APC/C)-dependent ubiquitination and subsequent destruction of cyclin B. Here, we established a system which, following pulse-chase labeling, allows monitoring cyclin B proteolysis in entire cell populations and facilitates the detection of interference by the mitotic checkpoint.

Equal distribution of chromosomes between the two daughter cells during cell division is a prerequisite for guaranteeing genetic stability 1. Inaccuracies ...

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