Name: 5-ethynyl-2'-deoxyuridine/phospho-histone h3 dual-labeling protocol for cell cycle progression analysis in drosophila neural stem cells
Uploaded: 2021-05-04T15:00:00
Description: Watch this Scientific Journal Video about 5-Ethynyl-2'-Deoxyuridine/Phospho-Histone H3 Dual-Labeling Protocol for Cell Cycle Progression Analysis in Drosophila Neural Stem Cells at JoVE.com

This work was supported by funding from the Swiss National Science Foundation (project grant 31003A_173188; www.snf.ch) and the University of Bern (www.unibe.ch) to BS. The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript.

1. Preparation of reagents and stocks for Click-it EdU assay
NOTE: Refer to the Table of Materials and Table 1 for details about the kit and reagents supplied with the kit.
<ol>
	<li>Bring the vials to room temperature before preparing the solutions.</li>
	<li>Prepare 10 mM EdU (component A) stock solution by adding 2 mL of dimethylsulfoxide (DMSO, component C). Mix well and store at -20 &#176;C.</li>
	<li>Prepare a working solution of Alexa Fluor 647-azide ...

<ol>
	<li>Harashima, H., Dissmeyer, N., Schnittger, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+cycle+control+across+the+eukaryotic+kingdom.">Cell cycle control across the eukaryotic kingdom.</a> Trends in Cell Biology. 23 (7), 345-356 (2013).</li><li>Vermeulen, K., Van Bockstaele, D. R., Berneman, Z. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cell+cycle:+a+review+of+regulation,+deregulation+and+therapeutic+targets+in+cancer.">The cell cycle: a review of regulation, deregulation and therapeutic targets in cancer.</a> Cell Proliferation. 36 (3), 131-149 (2003).</li><li>Pardee, A. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+restriction+point+for+control+of+normal+animal+cell+proliferation.">A restriction point for control of normal animal cell proliferation.</a> Proceedings of the National Academy of the Sciences of the United States of America. 71 (4), 1286-1290 (1974).</li><li>Gogendeau, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aneuploidy+causes+premature+differentiation+of+neural+and+intestinal+stem+cells.">Aneuploidy causes premature differentiation of neural and intestinal stem cells.</a> Nature Communications. 6, 8894 (2015).</li><li>Barnum, K. J., O'Connell, 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=Cell+cycle+regulation+by+checkpoints.">Cell cycle regulation by checkpoints.</a> Methods in Molecular Biology. 1170, 29-40 (2014).</li><li>Gratzner, H. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monoclonal+antibody+to+5-bromo-+and+5-iododeoxyuridine:+A+new+reagent+for+detection+of+DNA+replication.">Monoclonal antibody to 5-bromo- and 5-iododeoxyuridine: A new reagent for detection of DNA replication.</a> Science. 218 (4571), 474-475 (1982).</li><li>Salic, A., Mitchison, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+chemical+method+for+fast+and+sensitive+detection+of+DNA+synthesis+in+vivo.">A chemical method for fast and sensitive detection of DNA synthesis in vivo.</a> Proceedings of the National Academy of the Sciences of the United States of America. 105 (7), 2415-2420 (2008).</li><li>Kim, J. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+value+of+phosphohistone+H3+as+a+proliferation+marker+for+evaluating+invasive+breast+cancers:+A+comparative+study+with+Ki67.">The value of phosphohistone H3 as a proliferation marker for evaluating invasive breast cancers: A comparative study with Ki67.</a> Oncotarget. 8 (39), 65064-65076 (2017).</li><li>Homem, C. C., Knoblich, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophila+neuroblasts:+a+model+for+stem+cell+biology.">Drosophila neuroblasts: a model for stem cell biology.</a> Development. 139 (23), 4297-4310 (2012).</li><li>Daul, A. L., Komori, H., Lee, C. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EdU+(5-ethynyl-2'-deoxyuridine)+labeling+of+Drosophila+mitotic+neuroblasts.">EdU (5-ethynyl-2'-deoxyuridine) labeling of Drosophila mitotic neuroblasts.</a> Cold Spring Harbor Protocols. 2010 (7), 5461 (2010).</li><li>Chippalkatti, R., Egger, B., Suter, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mms19+promotes+spindle+microtubule+assembly+in+Drosophila+neural+stem+cells.">Mms19 promotes spindle microtubule assembly in Drosophila neural stem cells.</a> PLoS Genetics. 16, 1008913 (2020).</li><li>Daul, A. L., Komori, H., Lee, C. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunofluorescent+staining+of+Drosophila+larval+brain+tissue.">Immunofluorescent staining of Drosophila larval brain tissue.</a> Cold Spring Harbor Protocols. (7), (2010).</li><li>Mollinari, C., Lange, B., Gonzalez, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Miranda,+a+protein+involved+in+neuroblast+asymmetric+division,+is+associated+with+embryonic+centrosomes+of+Drosophila+melanogaster.">Miranda, a protein involved in neuroblast asymmetric division, is associated with embryonic centrosomes of Drosophila melanogaster.</a> Biology of the Cell. 94 (1), 1-13 (2002).</li><li>Schindelin, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fiji:+an+open-source+platform+for+biological-image+analysis.">Fiji: an open-source platform for biological-image analysis.</a> Nature Methods. 9 (7), 676-682 (2012).</li><li>Nag, R. N., Niggli, S., Sousa-Guimaraes, S., Vazquez-Pianzola, P., Suter, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mms19+is+a+mitotic+gene+that+permits+Cdk7+to+be+fully+active+as+a+Cdk-activating+kinase.">Mms19 is a mitotic gene that permits Cdk7 to be fully active as a Cdk-activating kinase.</a> Development. 145 (2), (2018).</li><li>Cabernard, C., Doe, C. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Live+imaging+of+neuroblast+lineages+within+intact+larval+brains+in+Drosophila.">Live imaging of neuroblast lineages within intact larval brains in Drosophila.</a> Cold Spring Harbor Protocols. 2013 (10), (2013).</li><li>Hartenstein, V., Spindler, S., Pereanu, W., Fung, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+development+of+the+Drosophila+larval+brain.">The development of the Drosophila larval brain.</a> Advances in Experimental Medicine and Biology. 628, 1-31 (2008).</li><li>Hebar, A., Rutgen, B. C., Selzer, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NVX-412,+a+new+oncology+drug+candidate,+induces+S-phase+arrest+and+DNA+damage+in+cancer+cells+in+a+p53-independent+manner.">NVX-412, a new oncology drug candidate, induces S-phase arrest and DNA damage in cancer cells in a p53-independent manner.</a> PLoS One. 7, 45015 (2012).</li><li>Wyllie, F. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=S+phase+cell-cycle+arrest+following+DNA+damage+is+independent+of+the+p53/p21(WAF1)+signalling+pathway.">S phase cell-cycle arrest following DNA damage is independent of the p53/p21(WAF1) signalling pathway.</a> Oncogene. 12 (5), 1077-1082 (1996).</li><li>Xu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+DNA+replication+and+induction+of+S+phase+cell+cycle+arrest+by+G-rich+oligonucleotides.">Inhibition of DNA replication and induction of S phase cell cycle arrest by G-rich oligonucleotides.</a> Journal of Biological Chemistry. 276 (46), 43221-43230 (2001).</li><li>Duronio, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developing+S-phase+control.">Developing S-phase control.</a> Genes &amp; Development. 26 (8), 746-750 (2012).</li><li>Turrero Garcia, M., Chang, Y., Arai, Y., Huttner, W. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=S-phase+duration+is+the+main+target+of+cell+cycle+regulation+in+neural+progenitors+of+developing+ferret+neocortex.">S-phase duration is the main target of cell cycle regulation in neural progenitors of developing ferret neocortex.</a> Journal of Comparative Neurology. 524 (3), 456-470 (2016).</li><li>Pereira, P. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+cell+cycle+kinetics+by+EdU+(5-ethynyl-2'-deoxyuridine)-coupled-fluorescence-intensity+analysis.">Quantification of cell cycle kinetics by EdU (5-ethynyl-2'-deoxyuridine)-coupled-fluorescence-intensity analysis.</a> Oncotarget. 8 (25), 40514-40532 (2017).</li><li>Sakaue-Sawano, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+spatiotemporal+dynamics+of+multicellular+cell-cycle+progression.">Visualizing spatiotemporal dynamics of multicellular cell-cycle progression.</a> Cell. 132 (3), 487-498 (2008).</li><li>Zielke, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fly-FUCCI:+A+versatile+tool+for+studying+cell+proliferation+in+complex+tissues.">Fly-FUCCI: A versatile tool for studying cell proliferation in complex tissues.</a> Cell Reports. 7 (2), 588-598 (2014).</li><li>Shen, Y., Vignali, P., Wang, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+profiling+cell+cycle+by+flow+cytometry+using+concurrent+staining+of+DNA+and+mitotic+markers.">Rapid profiling cell cycle by flow cytometry using concurrent staining of DNA and mitotic markers.</a> Bio-protocol. 7 (16), 2517 (2017).</li><li>Berger, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FACS+purification+and+transcriptome+analysis+of+drosophila+neural+stem+cells+reveals+a+role+for+Klumpfuss+in+self-renewal.">FACS purification and transcriptome analysis of drosophila neural stem cells reveals a role for Klumpfuss in self-renewal.</a> Cell Reports. 2 (2), 407-418 (2012).</li><li>Harzer, H., Berger, C., Conder, R., Schmauss, G., Knoblich, J. 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EdU incorporation and its subsequent &#39;click&#39; reaction with cell-permeable azide presents practical advantages of this technique over the BrdU method used earlier7. However, this reaction is catalyzed by Cu(I) ions, and several dyes may be unstable in the presence of this copper catalyst, as is clearly advised by the Click-it EdU kit manufacturer. When immunostaining experiments had been performed after executing the EdU detection step, the expected signal intensity was not observed with th...

The cell division cycle comprises a G1 phase (first gap phase), a replicative/S-phase, a G2 (second gap phase), and an M (mitotic) phase. Passing through these phases, the cell undergoes dramatic changes in cellular transcription, translation, and re-organization of cytoskeletal machinery1,2. In response to developmental and environmental cues, cells may temporarily cease to divide and become quiescent (G0) or differentiate and permanently cease to divide3. Other scenarios, such as DNA damage, may cause premature differentiation or apoptosis3,4. Response to such cues is mediated by cell cycle checkpoints, which act as a surveillance system to ensure the integrity of essential cellular processes before the cell commits to the next phase of the division cycle5. Therefore, studies on genes regulating DNA replication, checkpoints, and mitotic machinery need to analyze possible cell cycle progression defects that may occur in mutant cells or upon siRNA knockdown of these genes. Additionally, such analyses may be employed to test overall cell health as well as cellular responses to drug treatment.
5-bromo-2&#39;-deoxyuridine (BrdU) is a thymidine analog that is incorporated into DNA during replication6. This method was used extensively to identify cells in S-phase. However, the cells are then subjected to harsh DNA denaturation procedures to allow detection of BrdU through the use of anti-BrdU antibodies6. This harsh treatment may damage cellular epitopes and prevent further characterization of the sample through immunostaining. EdU incorporation and subsequent detection by a copper-catalyzed, &#39;click reaction&#39; with small, cell-permeable, fluorescently tagged azide dyes eliminates the need for harsh denaturation procedures7. This method, therefore, emerged as a more practical alternative to BrdU incorporation.
Further, pH3 has been described as a reliable marker for mitotic/M phase cells8. Histone H3 is a DNA-associated core histone protein that becomes phosphorylated in around the late G2 phase to early M phase and is de-phosphorylated toward the end of anaphase8. Several commercial antibodies can be used to detect pH3 using standard immunostaining protocols. Dual-staining of EdU and pH3 would therefore enable the detection of cells in S-phase as well as M-phase. Additionally, cells in the G1 and early G2 phase would not stain positively for either of the markers.
Drosophila neural stem cells or neuroblasts (NBs) offer a well-characterized stem cell model wherein cells divide asymmetrically to produce one identical self-renewing NB and a ganglion mother cell (GMC), which is fated for differentiation9. Additionally, several genetic tools and NB-specific antibodies make this system suitable for genetic manipulation and live-cell imaging. Consequently, several studies have utilized NBs to study genes regulating asymmetric divisions and cell fate determination9. Distinct populations of NBs exist in the central brain (CB) and the optic lobe (OL) of the larval brain9; CB NBs were used for the current study. These third instar larval CB NBs are large cells that are also suitable for studying factors regulating mitotic spindle assembly. A protocol to analyze cell cycle progression defects would be a vital tool in such studies.
Protocols published earlier employed commercial kits, such as Click-iT EdU Alexa Fluor Cell Proliferation Kit, which provide several reaction components and azide dyes tagged with a variety of Alexa Fluor dyes for EdU incorporation and detection10. However, the reagents supplied with such kits are not compatible with some fluorescent tags often used with secondary antibodies. This EdU detection kit (Click-iT EdU Alexa Fluor Cell Proliferation Kit supplied with Alexa Fluor 647-conjugated azide dye) was tested in Drosophila third instar larval NBs, and co-staining was attempted with antibodies against pH3 and Miranda, a marker for NBs. Further, Alexa Fluor 568- or Cy3-tagged secondary antibodies were used for detection of Miranda labeling on the plasma membrane of NBs11. However, the expected signal intensity and staining pattern (unpublished results) were not observed with these secondary antibodies when immunostaining was performed after EdU detection.
For EdU incorporation, the protocol described by Daul and colleagues required feeding of the larvae with Kankel-White medium mixed with EdU and bromophenol blue (BPB)10. The larvae fed on the EdU and BPB-spiked food, which could be seen by its blue color upon ingestion in the larval gut. Although this method was used for EdU incorporation in Mms19 loss-of-function (Mms19P) third instar larvae, the Mms19P larvae apparently did not feed as hardly any blue color was detected in the larval gut (unpublished results). The Mms19P larvae show drastic developmental deformities and eventually arrest in the third instar stage. This may somehow affect the feeding behavior of the third instar larvae and render the EdU-feeding protocol unsuitable for such cases.
After studying the available literature and working extensively on the standardization of essential steps, an alternative approach was proposed for EdU/pH3 dual-labeling in Drosophila NBs, which does not require feeding EdU to larvae. A previous study employed dual EdU/pH3 staining to analyze the cell cycle in NBs, but did not present a detailed protocol4. This presents an unnecessary hurdle for labs trying to implement this method. Furthermore, evaluating the compatibility of various reagents with the EdU kit and performing further optimization can be a time-consuming process. This paper presents a step-by-step protocol that covers EdU incorporation in dissected larval brains and immunostaining with anti-pH3 antibodies, followed by confocal microscopy and image analysis to allocate NBs to four distinct categories: G0/G1 phase, S phase, S&#62;G2/M (progression from S to G2/M), and M phase. The steps that need optimization are outlined and tips provided for image analysis of large datasets. Additionally, the EdU/pH3 readout in wild-type NBs is analyzed and compared with Mms19P&#160;NBs, which were recently reported to show a cell cycle delay11.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>fly stocks</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>P{EPgy2}Mms19EY00797/TM3, Sb1 Ser1 (Mms19p)</td>
			<td>Bloomington stock center</td>
			<td>#15477</td>
			<td>P-element insertion in the third exon of Mms19</td>
		</tr>
		<tr>
			<td>&#160;+; Mms19::eGFP, Mms19p</td>
			<td>Generated in house</td>
			<td></td>
			<td>eGFP-tagged Mms19 protein expressed in Mms19p background</td>
		</tr>
		<tr>
			<td>w1118</td>
			<td>Bloomington stock center</td>
			<td>#3605</td>
			<td>wild-type stock (w;+;+)</td>
		</tr>
		<tr>
			<td>Primary antibodies</td>
			<td></td>
			<td></td>
			<td>Dilution</td>
		</tr>
		<tr>
			<td>Rat anti-Miranda</td>
			<td>Abcam</td>
			<td>Ab197788</td>
			<td>1/250</td>
		</tr>
		<tr>
			<td>Rabbit anti-pH3</td>
			<td>Cell Signaling</td>
			<td>9701</td>
			<td>1/200</td>
		</tr>
		<tr>
			<td>Secondary antibodies</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Goat anti-Rat Cy3</td>
			<td>Jackson Immuno</td>
			<td>112-165-167</td>
			<td>1/150</td>
		</tr>
		<tr>
			<td>Goat anti-Rat Alexa Fluor 568</td>
			<td>Invitrogen</td>
			<td>A11077</td>
			<td>1/500</td>
		</tr>
		<tr>
			<td>Goat anti-Rabbit Alexa Fluor 488</td>
			<td>Invitrogen</td>
			<td>A27034</td>
			<td>1/500</td>
		</tr>
		<tr>
			<td>Reagent/Kit</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Aqua Poly/Mount mounting medium</td>
			<td>Polysciences Inc</td>
			<td>18606-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Click-it EdU incorporation kit, Alexa Flour 647</td>
			<td>Thermo Fischer Scientific</td>
			<td>C10340</td>
			<td></td>
		</tr>
		<tr>
			<td>Schneider&#8217;s Drosophila medium</td>
			<td>Thermo Fischer Scientific</td>
			<td>21720-024</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine serum albumin (BSA) fraction V</td>
			<td>Merck</td>
			<td>10735078001</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Fischer Scientific</td>
			<td>9002-93-1</td>
			<td>non-ionic detergent</td>
		</tr>
		<tr>
			<td>Software</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fiji (Imagej)</td>
			<td>https://imagej.net/Fiji</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Leica Application Suite (LAS X)</td>
			<td>Leica microsystems</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PRISM</td>
			<td>Graph pad software</td>
			<td>Version 5</td>
			<td></td>
		</tr>
		<tr>
			<td>Microsoft Excel</td>
			<td>Microsoft office</td>
			<td>2016</td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Leica TCS SP8 laser scanning confocal microscope with 63x oil-immersion, 1.4 NA Plan-apochromat objective</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Aqua Poly/Mount mounting medium</td>
			<td></td>
			<td></td>
			<td>water-soluble, non-fluorescing mounting medium</td>
		</tr>
		<tr>
			<td>Pyrex 3 or 9 depression glass spot plate</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Whatman filter paper</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

5-ethynyl-2'-deoxyuridine/phospho-histone h3 dual-labeling protocol for cell cycle progression analysis in drosophila neural stem cells

In vivo cell cycle progression analysis is routinely performed in studies on genes regulating mitosis and DNA replication. 5-Ethynyl-2'-deoxyuridine (EdU) has been utilized to investigate replicative/S-phase progression, whereas antibodies against phospho-histone H3 have been utilized to mark mitotic nuclei and cells. A combination of both labels would enable the classification of G0/G1 (Gap phase), S (replicative), and M (mitotic) phases and serve as an important tool to evaluate the effects of mitotic gene knockdowns or null mutants on cell cycle progression. However, the reagents used to mark EdU-labelled cells are incompatible with several secondary antibody-fluorescent tags. This complicates immunostaining, where primary and tagged secondary antibodies are used to mark pH3-positive mitotic cells. This paper describes a step-by-step protocol for the dual-labeling of EdU and pH3 in Drosophila larval neural stem cells, a system utilized extensively to study mitotic factors. Additionally, a protocol is provided for image analysis and quantification to allocate labeled cells in 3 distinct categories, G0/G1, S, S&gt;G2/M (progression from S to G2/M), and M phases.

The bi-lobed Drosophila third instar larval brain has been utilized as a model system to study fundamental cellular and developmental processes9. The focus of the current study was to present a protocol for analysis of cell cycle progression in EdU- and pH3-labeled NBs of the CB region (Figure 1). The CB NBs are sub-divided into type I and type II, and they display the characteristic asymmetric division pattern9. Each type I NB divisio...

Watch this Scientific Journal Video about 5-Ethynyl-2'-Deoxyuridine/Phospho-Histone H3 Dual-Labeling Protocol for Cell Cycle Progression Analysis in Drosophila Neural Stem Cells at JoVE.com

5-Ethynyl-2&#039;-Deoxyuridine/Phospho-Histone H3 Dual-Labeling Protocol for Cell Cycle Progression Analysis in Drosophila Neural Stem Cells

Cell cycle analysis with 5-ethynyl-2'-deoxyuridine (EdU) and phospho-histone H3 (pH3) labeling is a multi-step procedure that may require extensive optimization. Here, we present a detailed protocol that describes all steps for this procedure including image analysis and quantification to distinguish cells in different cell cycle phases.

5-Ethynyl-2'-Deoxyuridine/Phospho-Histone H3 Dual-Labeling Protocol for Cell Cycle Progression Analysis in Drosophila Neural Stem Cells

In vivo cell cycle progression analysis is routinely performed in studies on genes regulating mitosis and DNA replication. 5-Ethynyl-2'-deoxyuridine (EdU) ...

In this protocol, we not only provide a detailed explanation of each step of EDU incorporation and immunostaining, but also explain image acquisition, image processing, and provide some tips for analyzing large datasets. This technique allows for the allocation of cells in G1, S, and M phases. This will be particularly useful for cell cycle analysis on studies on non mutations affecting mitotic genes.We would expect people to struggle for two to three months if they do not have prior knowledge or experience with this technique. To begin, add Schneider's dissection medium or SM to two consecutive depressions of a gloss spot plate and add PBS to the subsequent depression. Using a pair of forceps, pick wandering third instar larvae and place them on a tissue ratted with PBS to clean off fly food residue.Place the larva in the depression with PBS followed by the consecutive depression containing SM.Next under a dissection microscope, use fine forceps to remove three quarters of the lower body of the larva. Then gently grab the larval mouth hooks with one pair of forceps and hold the cuticle of the other end with the other pair of forceps. Turn the larval head inside out by pushing the mouth hooks inward and simultaneously peeling off the tissue at the other end.Observe the larval brain with attached imaginal discs. Remove other tissues attached to the brain and transfer the brain to the subsequent consecutive depression with SM.Add 100 microliters of 100 micromolar EDU SM solution to another depression on the Pyrex plate and incubate approximately 5 to 10 dissected brains in this solution for 2 hours at 25 degrees Celsius. After fixation and immunostaining remove PBST and add the EDU detection cocktail to the dissected brains.Then incubate them at room temperature in the dark on a neutater. After 30 minutes, wash the samples twice with PBST for 10 minutes per wash in the dark. For DNA staining, prepare 5 micrograms per milliliter Hoechst 33342 solution.Remove PBST after the second wash and add 500 microliters of the Hoechst solution to the dissected brains, then incubate them in the dark. After 10 minutes, remove the Hoechst and wash the samples with PBST for 10 minutes. Tap the tube onto the lab bench and let the brains settle down.Remove the PBST from the tube, leaving behind 50 to 100 microliters. Cut the end of a 200 microliter micropipet tip and use it to transfer the brains onto a clean glass slide. Remove access PBST from the slide by blotting it with filter paper strips.Do not let the filter paper touch the brains. Put a drop of a water soluble, non fluorescing mounting medium onto the brains and orient the brains such that the ventral nerve cord faces the slide and the lobes face upwards. Arrange the brains in a single file so that it is easier to image the brains serially.Gently place a cover slip on top of the brain and incubate the slide overnight at 2 to 6 degrees Celsius. From the acquisition software select the 63 times objective. Put a drop of immersion oil on the cover slip just above the mounted brains to make it easier to locate the tissue through the eyepiece.Using the dappy Hoechst 33342 channel, find the brain through the eyepiece and then switch to the acquisition mode in the software. Set up 4 channels to image Hoechst 33342, Alexa floor 4 8 8, Alexa floor 5 6, 8, and Alexa floor 6 4 7. Use the dye assistant tool to automatically set up the selected dyes excitation lasers and emission filters.Set the field of view, such that it encompasses the entire brain lobe. Image the entire volume of the brain lobe by acquiring this tax spaced 0.8 micron apart. Store all images from an imaging session in a dot L I F library format.For image analysis, open Fiji, then drag, and drop the LIF files into Fiji. Select data browser from the stack viewing tab and use virtual stack from the memory management tab in the bio formats plugin. Observe the multi-channel image displayed in image J.Change the color of the channels from the menu bar, using image, color, and channels tool.And monitor the Miranda labeled neuroblasts, which appear as large round cells in the central brain region. Draw a region of interest using the ellipse tool over each neuroblast to avoid counting the neuroblast twice. From the image J menu bar, select analyze, tools, and ROI manager.Mark all neuroblasts in the current Z section and press T after marking each cell. Once all neuroblasts in the current Z-section are marked, change the channels to pH3 and EDU and manually count the number of EDU positive neuroblasts, pH3 positive neuroblasts, EDU and pH3 positive neuroblasts, and neuroblasts not staining for either marker. Search for neuroblasts and subsequent Z sections, delete old ROIs and add new ROIs to count neuroblasts in different stacks.Prepare a spreadsheet and calculate percentages of neuroblasts present in all four categories for each lobe. Prepare a bar graph using the spreadsheets software, showing the pools data for percentages of neuroblasts in each category. Central brain neuroblasts from third instar larval brains marked with Miranda, EDU, and pH3 are shown here.Cells were allocated to G1/G0, S, SG2/M, and M phases. In EDU pH3 analysis, a significantly higher proportion of MMS19, loss of function neuroblasts was found in the M phase compared to wild type neuroblasts. MMS19:eGFP expression in the MMS19 loss of function background rescued the proportion of cells in M phase to wild type levels.It is important not to use damaged brains for subsequent steps. And ED solution should be prepared freshly before starting dissections. This asset can be used as a quick initial screening to identify defects in specific cell cycle phases.This could then be followed up by a more detailed analysis of a particular phase.

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Research

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Biology

Counting Human Neural Stem Cells

Knowledge of the exact number of viable cells in a given volume of a cell suspension is required for many routine tissue culture manipulations, such as plating cells for immunocytochemistry or for cell transfections. This protocol describes a straightforward and fast method for differentiating between live and dead cells and quantifying the cell concentration and total cell number using a hemacytometer. This procedure first requires detaching cells from a growth surface and resuspending them in media. Next, the cells are diluted in a solution of Trypan blue (ideally to a concentration that will give 20-50 cells per quadrant) and placed in the hemacytometer. Finally, averaging the counts of viable cells in several randomly selected quadrants, dividing the average by the volume of one 1 mm2 quadrant (0.1 &mu;l) and multiplying by the dilution factor gives the number of cells per l. Multiplying this cell concentration by the total volume in &mu;l gives the total cell number. This protocol describes counting human neural stem/precursor cells (hNSPCs), but can also be used for many other cell types.

Knowledge of the exact number of viable cells is required for many tissue culture manipulations. This protocol describes how to differentiate between live and dead cells and quantify cells using a hemacytometer. Although it describes counting human neural stem/precursor cells (hNSPCs), it can be used for other cell types.

Knowledge of the exact number of viable cells in a given volume of a cell suspension is required for many routine tissue culture manipulations, such as ...

Passaging Human Neural Stem Cells

The ability to manipulate human neural stem/precursor cells (hNSPCs) in vitro provides a means to investigate their utility as cell transplants for therapeutic purposes as well as to explore many fundamental processes of human neural development and pathology.  This protocol presents a simple method of culturing and passaging hNSPCs in hopes of standardizing this technique and increasing reproducibility of human stem cell research.  The hNSPCs we use were isolated from cadaveric postnatal brain cortices by the National Human Neural Stem Cell Resource and grown as adherent cultures on flasks coated with fibronectin (Palmer et al., 2001; Schwartz et al., 2003).  We culture our hNSPCs in a DMEM:F12 serum-free media supplemented with EGF, FGF, and PDGF and passage them 1:2 approximately every seven days.  Using these conditions, the majority of the cells in the culture maintain a bipolar morphology and express markers of undifferentiated neural stem cells (such as nestin and sox2).

The ability to manipulate human neural stem/precursor cells (hNSPCs) in vitro allows to investigate their utility as cell transplants for therapeutic purposes and to explore human neural development. This protocol presents a method of culturing and passaging hNSPCs in hopes of increasing reproducibility of human stem cell research.

The ability to manipulate human neural stem/precursor cells (hNSPCs) in vitro provides a means to investigate their utility as cell transplants for ...

Immunocytochemistry: Human Neural Stem Cells

Immunocytochemistry is a very powerful and fairly straightforward method for determining the presence, subcellular localization, and relative abundance of an antigen of interest, most commonly a protein, in cultured cells. This protocol presents an easy-to-follow series of steps that will enable researchers to conserve primary and secondary antibodies while getting high quality, reproducible qualitative and quantitative data out of their staining. There are two aspects of this protocol that help to conserve the volume of antibody necessary for staining. For one, the cells are grown on small, circular coverslips that are placed in wells of a tissue culture plate. After fixation, the cells on coverslips can be removed from the wells of the plate. For antibody staining, the coverslip with cells is inverted onto a small drop of antibody solution on parafilm and is covered with a second piece of parafilm to prevent drying. Using this method, only ~25 &mu;l of antibody solution is needed for each coverslip (or sample) to be stained. This protocol describes immunostaining of human neural stem/precursor cells (hNSPCs), but can be used for many other cell types.

Immunocytochemistry is a powerful method to determine the presence, subcellular localization, and relative abundance of an antigen of interest in cultured cells. This protocol presents an easy-to-follow series of steps that will enable one to conserve antibodies and get the most out of one's staining.

Immunocytochemistry is a very powerful and fairly straightforward method for determining the presence, subcellular localization, and relative abundance of ...

Video Bioinformatics Analysis of Human Embryonic Stem Cell Colony Growth

Because video data are complex and are comprised of many images, mining information from video material is difficult to do without the aid of computer software.  Video bioinformatics is a powerful quantitative approach for extracting spatio-temporal data from video images using computer software to perform dating mining and analysis. In this article, we introduce a video bioinformatics method for quantifying the growth of human embryonic stem cells (hESC) by analyzing time-lapse videos collected in a Nikon BioStation CT incubator equipped with a camera for video imaging. In our experiments, hESC colonies that were attached to Matrigel were filmed for 48 hours in the BioStation CT.  To determine the rate of growth of these colonies, recipes were developed using CL-Quant software which enables users to extract various types of data from video images.  To accurately evaluate colony growth, three recipes were created. The first segmented the image into the colony and background, the second enhanced the image to define colonies throughout the video sequence accurately, and the third measured the number of pixels in the colony over time.  The three recipes were run in sequence on video data collected in a BioStation CT to analyze the rate of growth of individual hESC colonies over 48 hours. To verify the truthfulness of the CL-Quant recipes, the same data were analyzed manually using Adobe Photoshop software. When the data obtained using the CL-Quant recipes and Photoshop were compared, results were virtually identical, indicating the CL-Quant recipes were truthful. The method described here could be applied to any video data to measure growth rates of hESC or other cells that grow in colonies. In addition, other video bioinformatics recipes can be developed in the future for other cell processes such as migration, apoptosis, and cell adhesion.  

Video bioinformatics is the automated processing, analysis, understanding, and data mining of biological spatio-temporal data extracted from microscopic videos. The purpose of this article is to demonstrate a method for measuring human embryonic stem cell colony growth using a video bioinformatics method.

Because video data are complex and are comprised of many images, mining information from video material is difficult to do without the aid of computer ...

Analysis of Cell Cycle Position in Mammalian Cells

The regulation of cell proliferation is central to tissue morphogenesis during the development of multicellular organisms. Furthermore, loss of control of cell proliferation underlies the pathology of diseases like cancer. As such there is great need to be able to investigate cell proliferation and quantitate the proportion of cells in each phase of the cell cycle. It is also of vital importance to indistinguishably identify cells that are replicating their DNA within a larger population. Since a cell&prime;s decision to proliferate is made in the G1 phase immediately before initiating DNA synthesis and progressing through the rest of the cell cycle, detection of DNA synthesis at this stage allows for an unambiguous determination of the status of growth regulation in cell culture experiments.
DNA content in cells can be readily quantitated by flow cytometry of cells stained with propidium iodide, a fluorescent DNA intercalating dye. Similarly, active DNA synthesis can be quantitated by culturing cells in the presence of radioactive thymidine, harvesting the cells, and measuring the incorporation of radioactivity into an acid insoluble fraction. We have considerable expertise with cell cycle analysis and recommend a different approach. We Investigate cell proliferation using bromodeoxyuridine/fluorodeoxyuridine (abbreviated simply as BrdU) staining that detects the incorporation of these thymine analogs into recently synthesized DNA. Labeling and staining cells with BrdU, combined with total DNA staining by propidium iodide and analysis by flow cytometry1 offers the most accurate measure of cells in the various stages of the cell cycle. It is our preferred method because it combines the detection of active DNA synthesis, through antibody based staining of BrdU, with total DNA content from propidium iodide. This allows for the clear separation of cells in G1 from early S phase, or late S phase from G2/M. Furthermore, this approach can be utilized to investigate the effects of many different cell stimuli and pharmacologic agents on the regulation of progression through these different cell cycle phases.
In this report we describe methods for labeling and staining cultured cells, as well as their analysis by flow cytometry. We also include experimental examples of how this method can be used to measure the effects of growth inhibiting signals from cytokines such as TGF-&beta;1, and proliferative inhibitors such as the cyclin dependent kinase inhibitor, p27KIP1. We also include an alternate protocol that allows for the analysis of cell cycle position in a sub-population of cells within a larger culture5. In this case, we demonstrate how to detect a cell cycle arrest in cells transfected with the retinoblastoma gene even when greatly outnumbered by untransfected cells in the same culture. These examples illustrate the many ways that DNA staining and flow cytometry can be utilized and adapted to investigate fundamental questions of mammalian cell cycle control.

Determining the cell cycle position of a population of cells, or understanding how signals affect proliferation, can be readily measured by flow cytometry using this protocol. We report a simple experimental approach to staining cells and quantifying their position in the cell cycle.

The regulation of cell proliferation is central to tissue morphogenesis during the development of multicellular organisms. Furthermore, loss of control of ...

Reprogramming Human Somatic Cells into Induced Pluripotent Stem Cells (iPSCs) Using Retroviral Vector with GFP

Human embryonic stem cells (hESCs) are pluripotent and an invaluable cellular sources for in vitro disease modeling and regenerative medicine1. It has been previously shown that human somatic cells can be reprogrammed to pluripotency by ectopic expression of four transcription factors (Oct4, Sox2, Klf4 and Myc) and become induced pluripotent stem cells (iPSCs)2-4 . Like hESCs, human iPSCs are pluripotent and a potential source for autologous cells. Here we describe the protocol to reprogram human fibroblast cells with the four reprogramming factors cloned into GFP-containing retroviral backbone4. Using the following protocol, we generate human iPSCs in 3-4 weeks under human ESC culture condition. Human iPSC colonies closely resemble hESCs in morphology and display the loss of GFP fluorescence as a result of retroviral transgene silencing. iPSC colonies isolated mechanically under a fluorescence microscope behave in a similar fashion as hESCs. In these cells, we detect the expression of multiple pluripotency genes and surface markers.

Reprogramming Human Somatic Cells into Induced Pluripotent Stem Cells iPSCs Using Retroviral Vector with GFP

A method to generate human induced pluripotent stem cells (iPSCs) via retrovirus-mediated ectopic expression of OCT4, SOX2, KLF4 and MYC is described. A practical way to identify human iPSC colonies based on GFP expression is also discussed.

Human embryonic stem cells (hESCs) are pluripotent and an invaluable cellular sources for in vitro disease modeling and regenerative medicine1. It has ...

Measuring Cell Cycle Progression Kinetics with Metabolic Labeling and Flow Cytometry

Precise control of the initiation and subsequent progression through the various phases of the cell cycle are of paramount importance in proliferating cells. Cell cycle division is an integral part of growth and reproduction and deregulation of key cell cycle components have been implicated in the precipitating events of carcinogenesis 1,2. Molecular agents in anti-cancer therapies frequently target biological pathways responsible for the regulation and coordination of cell cycle division 3. Although cell cycle kinetics tend to vary according to cell type, the distribution of cells amongst the four stages of the cell cycle is rather consistent within a particular cell line due to the consistent pattern of mitogen and growth factor expression. Genotoxic events and other cellular stressors can result in a temporary block of cell cycle progression, resulting in arrest or a temporary pause in a particular cell cycle phase to allow for instigation of the appropriate response mechanism. 
The ability to experimentally observe the behavior of a cell population with reference to their cell cycle progression stage is an important advance in cell biology. Common procedures such as mitotic shake off, differential centrifugation or flow cytometry-based sorting are used to isolate cells at specific stages of the cell cycle 4-6. These fractionated, cell cycle phase-enriched populations are then subjected to experimental treatments. Yield, purity and viability of the separated fractions can often be compromised using these physical separation methods. As well, the time lapse between separation of the cell populations and the start of experimental treatment, whereby the fractionated cells can progress from the selected cell cycle stage, can pose significant challenges in the successful implementation and interpretation of these experiments.
Other approaches to study cell cycle stages include the use of chemicals to synchronize cells. Treatment of cells with chemical inhibitors of key metabolic processes for each cell cycle stage are useful in blocking the progression of the cell cycle to the next stage. For example, the ribonucleotide reductase inhibitor hydroxyurea halts cells at the G1/S juncture by limiting the supply of deoxynucleotides, the building blocks of DNA. Other notable chemicals include treatment with aphidicolin, a polymerase alpha inhibitor for G1 arrest, treatment with colchicine and nocodazole, both of which interfere with mitotic spindle formation to halt cells in M phase and finally, treatment with the DNA chain terminator 5-fluorodeoxyridine to initiate S phase arrest 7-9. Treatment with these chemicals is an effective means of synchronizing an entire population of cells at a particular phase. With removal of the chemical, cells rejoin the cell cycle in unison. Treatment of the test agent following release from the cell cycle blocking chemical ensures that the drug response elicited is from a uniform, cell cycle stage-specific population. However, since many of the chemical synchronizers are known genotoxic compounds, teasing apart the participation of various response pathways (to the synchronizers vs. the test agents) is challenging. 
Here we describe a metabolic labeling method for following a subpopulation of actively cycling cells through their progression from the DNA replication phase, through to the division and separation of their daughter cells. Coupled with flow cytometry quantification, this protocol enables for measurement of kinetic progression of the cell cycle in the absence of either mechanically- or chemically- induced cellular stresses commonly associated with other cell cycle synchronization methodologies 10. In the following sections we will discuss the methodology, as well as some of its applications in biomedical research.

Tracking subtle changes in the progression and kinetics of cell cycle stages can be accomplished by use of a combination of metabolic labeling of nucleic acids with BrdU and total genomic DNA staining via Propidium Iodide. This method avoids the need of chemical synchronization of cycling cells, thereby preventing the introduction of non-specific DNA damage, which in turn affects cell cycle progression.

Precise control of the initiation and subsequent progression through the various phases of the cell cycle are of paramount importance in proliferating ...

Induction and Analysis of Epithelial to Mesenchymal Transition

Epithelial to mesenchymal transition (EMT) is essential for proper morphogenesis during development. Misregulation of this process has been implicated as a key event in fibrosis and the progression of carcinomas to a metastatic state. Understanding the processes that underlie EMT is imperative for the early diagnosis and clinical control of these disease states. Reliable induction of EMT in vitro is a useful tool for drug discovery as well as to identify common gene expression signatures for diagnostic purposes. Here we demonstrate a straightforward method for the induction of EMT in a variety of cell types. Methods for the analysis of cells pre- and post-EMT induction by immunocytochemistry are also included. Additionally, we demonstrate the effectiveness of this method through antibody-based array analysis and migration/invasion assays.

A straightforward method is described for the induction of epithelial to mesenchymal transition (EMT) in a variety of cell types. Methods for the analysis of cells in EMT states by immunocytochemistry are included.

Epithelial  to mesenchymal transition (EMT) is essential for proper morphogenesis during  development. Misregulation of this  process has been implicated ...

Efficient Generation Human Induced Pluripotent Stem Cells from Human Somatic Cells with Sendai-virus

A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs include modeling pathogenesis of human genetic diseases, autologous cell therapy after gene correction, and personalized drug screening by providing a source of patient-specific and symptom relevant cells. However, there are several hurdles to overcome, such as eliminating the remaining reprogramming factor transgene expression after human iPSCs production. More importantly, residual transgene expression in undifferentiated human iPSCs could hamper proper differentiations and misguide the interpretation of disease-relevant in vitro phenotypes. With this reason, integration-free and/or transgene-free human iPSCs have been developed using several methods, such as adenovirus, the piggyBac system, minicircle vector, episomal vectors, direct protein delivery and synthesized mRNA. However, efficiency of reprogramming using integration-free methods is quite low in most cases.
Here, we present a method to isolate human iPSCs by using Sendai-virus (RNA virus) based reprogramming system. This reprogramming method shows consistent results and high efficiency in cost-effective manner.

Here, we present our established method to reprogram human somatic cells into transgene-free human iPSCs with Sendai virus, which shows consistent outcome and enhanced efficiency.

A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs ...

Profiling Individual Human Embryonic Stem Cells by Quantitative RT-PCR

Heterogeneity of stem cell population hampers detailed understanding of stem cell biology, such as their differentiation propensity toward different lineages. A single cell transcriptome assay can be a new approach for dissecting individual variation. We have developed the single cell qRT-PCR method, and confirmed that this method works well in several gene expression profiles. In single cell level, each human embryonic stem cell, sorted by OCT4::EGFP positive cells, has high expression in OCT4, but a different level of NANOG expression. Our single cell gene expression assay should be useful to interrogate population heterogeneities.

Single cell gene expression assay is needed for understanding stem cell heterogeneities.

Heterogeneity of stem cell population hampers detailed understanding of stem cell biology, such as their differentiation propensity toward different ...