Name: quantitative analysis of protein expression to study lineage specification in mouse preimplantation embryos
Uploaded: 2016-02-22T13:00:00.000+00:00
Duration: 11 min 25 s
Description: Watch this Scientific Journal Video about Quantitative Analysis of Protein Expression to Study Lineage Specification in Mouse Preimplantation Embryos at JoVE.com

The authors would like to thank Stefano Di Talia, Alberto Puliafito, Venkatraman Seshan and Panagiotis Xenopoulos, for input on data handling, analysis and representation, Berenika Plusa for assistance in the design of the immunofluorescence protocol and antibody testing and members of the Hadjantonakis lab for comments on the manuscript and on the development of this protocol. Work in our lab is supported by the National Institutes of Health R01-HD052115 and R01-DK084391, and by NYSTEM N13G-236.

<ol>
	<li>Saiz, N., Plusa, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+cell+fate+decisions+in+the+mouse+embryo.">Early cell fate decisions in the mouse embryo.</a> Reproduction. 145 (3), R65-R80 (2013).</li><li>Schrode, N., Xenopoulos, P., Piliszek, A., Frankenberg, S., Plusa, B., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomy+of+a+blastocyst:+cell+behaviors+driving+cell+fate+choice+and+morphogenesis+in+the+early+mouse+embryo.">Anatomy of a blastocyst: cell behaviors driving cell fate choice and morphogenesis in the early mouse embryo.</a> Genesis. 51 (4), 219-233 (2013).</li><li>Saiz, N., Plusa, B., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+cells+get+together:+High-resolution+approaches+to+study+the+dynamics+of+early+mouse+development.">Single cells get together: High-resolution approaches to study the dynamics of early mouse development.</a> Seminars in cell &amp; developmental biology. , (2015).</li><li>Lou, X., Kang, M., Xenopoulos, P., Mu&#241;oz-Descalzo, S., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Rapid+and+Efficient+2D/3D+Nuclear+Segmentation+Method+for+Analysis+of+Early+Mouse+Embryo+and+Stem+Cell+Image+Data.">A Rapid and Efficient 2D/3D Nuclear Segmentation Method for Analysis of Early Mouse Embryo and Stem Cell Image Data.</a> Stem Cell Reports. 2 (3), 382-397 (2014).</li><li>Le Bin, G. C., Mu&#241;oz-Descalzo, 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=Oct4+is+required+for+lineage+priming+in+the+developing+inner+cell+mass+of+the+mouse+blastocyst.">Oct4 is required for lineage priming in the developing inner cell mass of the mouse blastocyst.</a> Development. 141 (5), 1001-1010 (2014).</li><li>Schrode, N., Saiz, N., Di Talia, S., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GATA6+Levels+Modulate+Primitive+Endoderm+Cell+Fate+Choice+and+Timing+in+the+Mouse+Blastocyst.">GATA6 Levels Modulate Primitive Endoderm Cell Fate Choice and Timing in the Mouse Blastocyst.</a> Developmental Cell. 29 (4), 454-467 (2014).</li><li>Xenopoulos, P., Kang, M., Puliafito, A., Di Talia, S., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterogeneities+in+Nanog+Expression+Drive+Stable+Commitment+to+Pluripotency+in+the+Mouse+Blastocyst.">Heterogeneities in Nanog Expression Drive Stable Commitment to Pluripotency in the Mouse Blastocyst.</a> Cell Reports. 10 (9), 1508-1520 (2015).</li><li>Saiz, N., Kang, M., 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=Quantitative+analyses+for+elucidating+mechanisms+of+cell+fate+commitment+in+the+mouse+blastocyst.">Quantitative analyses for elucidating mechanisms of cell fate commitment in the mouse blastocyst.</a> Proceedings of SPIE. 9334, (2015).</li><li>Fleming, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+quantitative+analysis+of+cell+allocation+to+trophectoderm+and+inner+cell+mass+in+the+mouse+blastocyst.">A quantitative analysis of cell allocation to trophectoderm and inner cell mass in the mouse blastocyst.</a> Developmental biology. 119 (2), 520-531 (1987).</li><li>Dietrich, J. -. E., Hiiragi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stochastic+patterning+in+the+mouse+pre-implantation+embryo.">Stochastic patterning in the mouse pre-implantation embryo.</a> Development. 134 (23), 4219-4231 (2007).</li><li>Plusa, B., Piliszek, A., Frankenberg, S., Artus, J., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+sequential+cell+behaviours+direct+primitive+endoderm+formation+in+the+mouse+blastocyst.">Distinct sequential cell behaviours direct primitive endoderm formation in the mouse blastocyst.</a> Development. 135 (18), 3081-3091 (2008).</li><li>Gerbe, F., Cox, B., Rossant, J., Chazaud, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+expression+of+Lrp2+pathway+members+reveals+progressive+epithelial+differentiation+of+primitive+endoderm+in+mouse+blastocyst.">Dynamic expression of Lrp2 pathway members reveals progressive epithelial differentiation of primitive endoderm in mouse blastocyst.</a> Developmental biology. 313 (2), 594-602 (2008).</li><li>Nichols, J., Silva, J., Roode, M., Smith, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suppression+of+Erk+signalling+promotes+ground+state+pluripotency+in+the+mouse+embryo.">Suppression of Erk signalling promotes ground state pluripotency in the mouse embryo.</a> Development. 136 (19), 3215-3222 (2009).</li><li>Yamanaka, Y., Lanner, F., Rossant, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FGF+signal-dependent+segregation+of+primitive+endoderm+and+epiblast+in+the+mouse+blastocyst.">FGF signal-dependent segregation of primitive endoderm and epiblast in the mouse blastocyst.</a> Development. 137 (5), 715-724 (2010).</li><li>Morris, S. A., Teo, R. T. Y., Li, H., Robson, P., Glover, D. M., Zernicka-Goetz, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Origin+and+formation+of+the+first+two+distinct+cell+types+of+the+inner+cell+mass+in+the+mouse+embryo.">Origin and formation of the first two distinct cell types of the inner cell mass in the mouse embryo.</a> Proceedings of the National Academy of Sciences of the United States of America. 107 (14), 6364-6369 (2010).</li><li>Artus, J., Panthier, J. -. J., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+PDGF+signaling+in+expansion+of+the+extra-embryonic+endoderm+lineage+of+the+mouse+blastocyst.">A role for PDGF signaling in expansion of the extra-embryonic endoderm lineage of the mouse blastocyst.</a> Development. 137 (20), 3361-3372 (2010).</li><li>Artus, J., Piliszek, A., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+primitive+endoderm+lineage+of+the+mouse+blastocyst:+Sequential+transcription+factor+activation+and+regulation+of+differentiation+by+Sox17.">The primitive endoderm lineage of the mouse blastocyst: Sequential transcription factor activation and regulation of differentiation by Sox17.</a> Developmental biology. 350 (2), 393-404 (2011).</li><li>Kang, M., Piliszek, A., Artus, J., Hadjantonakis, A. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FGF4+is+required+for+lineage+restriction+and+salt-and-pepper+distribution+of+primitive+endoderm+factors+but+not+their+initial+expression+in+the+mouse.">FGF4 is required for lineage restriction and salt-and-pepper distribution of primitive endoderm factors but not their initial expression in the mouse.</a> Development. 140 (2), 267-279 (2013).</li><li>Bessonnard, S., De Mot, L., 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=Gata6,+Nanog+and+Erk+signaling+control+cell+fate+in+the+inner+cell+mass+through+a+tristable+regulatory+network.">Gata6, Nanog and Erk signaling control cell fate in the inner cell mass through a tristable regulatory network.</a> Development. 141 (19), 3637-3648 (2014).</li><li>Behringer, R. R., Gertsenstein, M., Vintersten Nagy, K., Nagy, 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> Manipulating the mouse embryo: a laboratory manual. , (2014).</li><li>Czechanski, A., Byers, 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=Derivation+and+characterization+of+mouse+embryonic+stem+cells+from+permissive+and+nonpermissive+strains.">Derivation and characterization of mouse embryonic stem cells from permissive and nonpermissive strains.</a> Nature Protocols. 9 (3), 559-574 (2014).</li><li>Frankenberg, S., Shaw, G., Freyer, C., Pask, A. J., Renfree, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+cell+lineage+specification+in+a+marsupial:+a+case+for+diverse+mechanisms+among+mammals.">Early cell lineage specification in a marsupial: a case for diverse mechanisms among mammals.</a> Development. 140, 965-975 (2013).</li><li>Artus, J., Vandormael-Pournin, S., Fr&#246;din, M., Nacerddine, K., Babinet, C., Cohen-Tannoudji, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impaired+mitotic+progression+and+preimplantation+lethality+in+mice+lacking+OMCG1,+a+new+evolutionarily+conserved+nuclear+protein.">Impaired mitotic progression and preimplantation lethality in mice lacking OMCG1, a new evolutionarily conserved nuclear protein.</a> Molecular and cellular biology. 25 (14), 6289-6302 (2005).</li><li>Saiz, N., Grabarek, J. B., Sabherwal, N., Papalopulu, N., Plusa, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atypical+protein+kinase+C+couples+cell+sorting+with+primitive+endoderm+maturation+in+the+mouse+blastocyst.">Atypical protein kinase C couples cell sorting with primitive endoderm maturation in the mouse blastocyst.</a> Development. 140 (21), 4311-4322 (2013).</li></ol>

The authors declare no conflicts of interest.

The present protocol describes a method to perform a quantitative analysis of whole-mount immunofluorescence on preimplantation stage mouse embryos. A robust immunofluorescence protocol 22 is followed by high-resolution, whole-mount confocal imaging and by image segmentation using a tailored piece of software 4. While the choice of immunofluorescence protocol is not critical, we find the one presented here 22 to be fast, reliable and to provide robust signal for many of the antibodies we ...

The mouse preimplantation embryo is a paradigm to study the emergence and maintenance of pluripotency in vivo, as well as a model for the study of cell fate specification and de novo epithelialization in mammals. The preimplantation stages of mammalian development are dedicated to the establishment of the three cell lineages that make up the blastocyst, namely the pluripotent epiblast - which gives rise to most somatic tissues and germ cells - and two extraembryonic lineages, the trophectoderm (TE) and the primitive endoderm (PrE) (Figure 1A) 1,2. This protocol describes the procedures to (1) harvest and fix preimplantation stage mouse embryos, (2) perform immunofluorescence to label proteins of interest, (3) carry out whole-mount imaging using a confocal microscope with z-sectioning capabilities and (4) perform nuclear segmentation of confocal images and subsequent quantitative image analyses. This pipeline allows the unbiased measurement of protein levels for the assignment of cell identities to characterize subpopulations of cells in situ. This protocol can be carried out in as little as 3 - 4 days for a single litter (generally up to 10 mouse embryos), from embryo collection to the data analysis (Figure 1B). The simultaneous analysis of several litters would increase the imaging and data analysis time burden, thus extending the overall length of the protocol.
The preimplantation stage mouse embryo is an experimentally tractable system which, given its small size and stereotypical morphology 3, is well suited for in toto imaging of cellular processes with single-cell resolution. To carry out an unbiased, systems-level analysis of a statistically relevant number of embryos, an automated, quantitative analysis pipeline is desirable. However, due to the high nuclear density of the inner cell mass (ICM) of the blastocyst (Figure 1A, 2D), conventional image segmentation platforms fail to provide sufficient accuracy to establish an automated or semi-automated workflow. On the other hand, manual segmentation, while accurate, does not allow the processing of large cohorts of cells and embryos, nor is it suitable for a reproducible, unbiased determination of cell identities - which is especially critical when studying developmental stages where patterns of marker expression have not fully resolved (e.g., do not exhibit a binary distribution across a population). We have recently developed and validated an image segmentation method tailored for mouse preimplantation stage embryos and for mouse embryonic stem cells (ESCs) that achieves high accuracy, while requiring minimal user input 4-8.
The analysis pipeline presented here revolves around the MATLAB-based image segmentation tool Modular Interactive Nuclear Segmentation (MINS) 4. MINS performs unsupervised nuclear segmentation on large batches of confocal Z-stacks after the user has established a minimal number of image properties, using a graphical user interface (GUI) (Table 1) 4. This pipeline has proven efficient for the generation of high throughput data on protein expression and cell localization in both wild type, experimentally treated and genetically modified embryos and ESCs 5-7. In the present protocol, we describe the application of MINS to the segmentation of preimplantation-stage embryo images. For examples of MINS performance on ESCs please refer to 4,7. The automated nuclear segmentation step significantly reduces the time burden of the cell identification process, whereas the spatial and fluorescence intensity measurements allow an unbiased determination of cell identities and the generation of three-dimensional maps of gene expression domains and cell position in the embryo (Figure 1C). Moreover, the scalability of this workflow makes it applicable to the analysis of individual litters through large cohorts of experimentally treated embryos, or embryos of different genetic backgrounds 5,6. MINS is freely available at&#160; http://katlab-tools.org (the software requires a MATLAB license).
No approach developed to date allows the generation of such in-depth data on protein expression and cell localization in mouse preimplantation embryos. All attempts thus far at quantifying these types of data have been restricted to the manual determination and quantitation of cell numbers for different populations in the embryo (either entirely manually, or software-assisted) 9-19. This approach (incorporating MINS software) has been tailored for and tested on mouse preimplantation embryos and ESCs; nevertheless its performance on other systems with high nuclear density, although yet untested, is expected to be equivalent.

<table><tbody><tr><td>&lt;strong&gt;Embryo collection&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Blunt probe for plug checking</td><td>Roboz</td><td>RS-9580</td><td></td></tr><tr><td>Forceps</td><td>Roboz</td><td>RS-4978</td><td></td></tr><tr><td>Surgery scissors</td><td>Roboz</td><td>RS-5910</td><td></td></tr><tr><td>Glass Pasteur pipettes</td><td>Fisher</td><td>13-678-20C</td><td></td></tr><tr><td>Pre-assembled aspirator tube &amp;amp; mouthpiece</td><td>Sigma</td><td>A5177</td><td></td></tr><tr><td>Longer rubber tubing</td><td>Fisher</td><td>14-178-2AA&amp;nbsp;&amp;nbsp;&amp;nbsp;</td><td></td></tr><tr><td>M2</td><td>Millipore</td><td>MR-015-D</td><td></td></tr><tr><td>FHM</td><td>Millipore</td><td>MR-024-D</td><td></td></tr><tr><td>Acid Tyrode&#039;s solution</td><td>Millipore</td><td>MR-004-D</td><td></td></tr><tr><td>Penicillin/Streptomycin</td><td>Gibco</td><td>15140</td><td></td></tr><tr><td>Bovine Serum Albumin&amp;nbsp;</td><td>Sigma</td><td>A9647</td><td></td></tr><tr><td>4-well plates</td><td>Nunc/Thermo-Fisher</td><td>12-566-300&amp;nbsp;&amp;nbsp;&amp;nbsp;</td><td></td></tr><tr><td>&lt;strong&gt;Immunofluorescence&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>96-well U-bottom plates</td><td>Fisher</td><td>14-245-73</td><td></td></tr><tr><td>Triton X-100</td><td>Sigma</td><td>T8787</td><td></td></tr><tr><td>Glycine</td><td>Sigma</td><td>G7403</td><td></td></tr><tr><td>Horse serum</td><td>Sigma</td><td>H0146</td><td></td></tr><tr><td>&lt;strong&gt;Primary antibodies&lt;/strong&gt;</td><td></td><td></td><td>&lt;strong&gt;Concentration&lt;/strong&gt;</td></tr><tr><td>CDX2</td><td>Biogenex</td><td>AM392-5M</td><td>1:200</td></tr><tr><td>GATA6</td><td>R&amp;amp;D</td><td>AF1700</td><td>1:100</td></tr><tr><td>GATA4</td><td>Santa Cruz</td><td>sc-9053</td><td>1:100, 10 min fixation</td></tr><tr><td>GATA4</td><td>Santa Cruz</td><td>sc-1237</td><td>1:100, O/N fixation</td></tr><tr><td>SOX17</td><td>R&amp;amp;D</td><td>AF1924</td><td>1:100</td></tr><tr><td>Nanog</td><td>ReproCELL</td><td>RCAB0002P-F</td><td>1:500</td></tr><tr><td>OCT4</td><td>Santa Cruz</td><td>sc-5279</td><td>1:100, 10 min to O/N fixation</td></tr><tr><td>DAB2</td><td>BD</td><td>BD-610464</td><td>1:200</td></tr><tr><td>Secondary antibodies</td><td>Life Technologies</td><td>Various</td><td>1:500</td></tr><tr><td>Hoechst 33342</td><td>Life Technologies</td><td>H3570</td><td></td></tr><tr><td>&lt;strong&gt;Imaging&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>35 mm glass-bottom dishes</td><td>MatTek</td><td>P35G-1.5-14-C</td><td></td></tr><tr><td>&lt;strong&gt;Segmentation&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Computer running 64-bit Windows OS</td><td></td><td>n/a</td><td>Verify minimal system requirements at http://katlab-tools.org and in Lou et al., (2014) Stem Cell Reports</td></tr><tr><td>MATLAB (software)</td><td>Mathworks</td><td>n/a</td><td></td></tr><tr><td>MINS (software)</td><td>Free</td><td>n/a</td><td>http://katlab-tools.org</td></tr></tbody></table>

quantitative analysis of protein expression to study lineage specification in mouse preimplantation embryos

This protocol presents a method to perform quantitative, single-cell in situ analyses of protein expression to study lineage specification in mouse preimplantation embryos. The procedures necessary for embryo collection, immunofluorescence, imaging on a confocal microscope, and image segmentation and analysis are described. This method allows quantitation of the expression of multiple nuclear markers and the spatial (XYZ) coordinates of all cells in the embryo. It takes advantage of MINS, an image segmentation software tool specifically developed for the analysis of confocal images of preimplantation embryos and embryonic stem cell (ESC) colonies. MINS carries out unsupervised nuclear segmentation across the X, Y and Z dimensions, and produces information on cell position in three-dimensional space, as well as nuclear fluorescence levels for all channels with minimal user input. While this protocol has been optimized for the analysis of images of preimplantation stage mouse embryos, it can easily be adapted to the analysis of any other samples exhibiting a good signal-to-noise ratio and where high nuclear density poses a hurdle to image segmentation (e.g., expression analysis of embryonic stem cell (ESC) colonies, differentiating cells in culture, embryos of other species or stages, etc.).

To facilitate data interpretation and presentation, care should be taken not to damage the embryos during collection and manipulation, so that all cells and their relative position can be analyzed. Figure 2A - D shows examples of intact blastocysts at different stages with an expanded cavity. Should damage occur, extra care should be taken when analyzing and interpreting results.
The quality and reliability of t...

Watch this Scientific Journal Video about Quantitative Analysis of Protein Expression to Study Lineage Specification in Mouse Preimplantation Embryos at JoVE.com

Quantitative Analysis of Protein Expression to Study Lineage Specification in Mouse Preimplantation Embryos

This protocol presents a method to perform quantitative, single-cell in situ analysis of protein expression to study lineage specification in mouse preimplantation embryos. The procedures necessary for collection of blastocysts, whole-mount immunofluorescent detection of proteins, imaging of samples on a confocal microscope, and nuclear segmentation and image analysis are described.

This protocol presents a method to perform quantitative, single-cell in situ analyses of protein expression to study lineage specification in mouse ...

quantitative-analysis-protein-expression-to-study-lineage

Research

JoVE Journal

Developmental Biology

10.8K Views.  Sloan Kettering Institute. This protocol presents a method to perform quantitative, single-cell in situ analysis of protein expression to study lineage specification in mouse preimplantation embryos. The procedures necessary for collection of blastocysts, whole-mount immunofluorescent detection of proteins, imaging of samples on a confocal microscope, and nuclear segmentation and image analysis are described.

Video: Quantitative Analysis of Protein Expression to Study Lineage Specification in Mouse Preimplantation Embryos

Loss- and Gain-of-function Approach to Investigate Early Cell Fate Determinants in Preimplantation Mouse Embryos

Gene silencing and overexpression techniques are instrumental for the identification of genes involved in embryonic development. Direct target gene modification in preimplantation embryos provides a means to study the underlying mechanisms of genes implicated in, for instance, cellular differentiation into the trophectoderm (TE) and the inner cell mass (ICM). Here, we describe a protocol that examines the role of neogenin as an authentic receptor for initial cell fate determination in preimplantation mouse embryos. First, we discuss the experimental manipulations that were used to produce gain and loss of neogenin function by microinjecting neogenin cDNA and shRNA; the effectiveness of this approach was confirmed by a strong correlation between the pair-wise expression levels of either red fluorescent protein (RFP) or green fluorescent protein (GFP) and the immunocytochemical quantification of neogenin expression. Secondly, overexpression of neogenin in preimplantation mouse embryos leads to normal ICM development while neogenin knockdown causes the ICM to develop abnormally, implying that neogenin could be a receptor that relays extracellular cues to drive blastomeres to early cell fates. Given the success of this detailed protocol in investigating the function of a novel embryonic developmental stage-specific receptor, we propose that it has the potential to aid in exploration and identification of other stage-specific genes during embryogenesis.

The goal of this protocol is to describe a loss- and gain-of function method that is applicable to identify neogenin as a stage-specific receptor that leads to trophectoderm and inner cell mass differentiation in preimplantation mouse embryos.

 Gene silencing and overexpression techniques are instrumental for the identification of genes involved in embryonic development. Direct target gene ...

Temporal Ordering of Dynamic Expression Data from Detailed Spatial Expression Maps

During somitogenesis, pairs of epithelial somites form in a progressive manner, budding off from the anterior end of the pre-somitic mesoderm (PSM) with a strict species-specific periodicity. The periodicity of the process is regulated by a molecular oscillator, known as the "segmentation clock," acting in the PSM cells. This clock drives the oscillatory patterns of gene expression across the PSM in a posterior-anterior direction. These so-called clock genes are key components of three signaling pathways: Wnt, Notch, and fibroblast growth factor (FGF). In addition, Notch signaling is essential for synchronizing intracellular oscillations in neighboring cells. We recently gained insight into how this may be mechanistically regulated. Upon ligand activation, the Notch receptor is cleaved, releasing the intracellular domain (NICD), which moves to the nucleus and regulates gene expression. NICD is highly labile, and its phosphorylation-dependent turnover acts to restrict Notch signaling. The profile of NICD production (and degradation) in the PSM is known to be oscillatory and to resemble that of a clock gene. We recently reported that both the Notch receptor and the Delta ligand, which mediate intercellular coupling, themselves exhibit dynamic expression at both the mRNA and protein levels. In this article, we describe the sensitive detection methods and detailed image analysis tools that we used, in combination with the computational modeling that we designed, to extract and overlay expression data from distinct points in the expression cycle. This allowed us to construct a spatio-temporal picture of the dynamic expression profile for the receptor, the ligand, and the Notch target clock genes throughout an oscillation cycle. Here, we describe the protocols used to generate and culture the PSM explants, as well as the procedure to stain for the mRNA or protein. We also explain how the confocal images were subsequently analyzed and temporally ordered computationally to generate ordered sequences of clock expression snapshots, hereafter defined as "kymographs," for the visualization of the spatiotemporal expression of Delta-like1 (Dll1) and Notch1 throughout the PSM.

The segmentation clock drives oscillatory gene expression across the pre-somitic mesoderm (PSM). Dynamic Notch activity is key to this process. We use imaging and computational analyses to extract temporal dynamics from spatial expression data to demonstrate that Delta ligand and Notch receptor expression oscillate in the vertebrate PSM.

During somitogenesis, pairs of epithelial somites form in a progressive manner, budding off from the anterior end of the pre-somitic mesoderm (PSM) with a ...

Robust Comparison of Protein Levels Across Tissues and Throughout Development Using Standardized Quantitative Western Blotting

Western blotting is a technique that is commonly used to detect and quantify protein expression. Over the years, this technique has led to many advances in both basic and clinical research. However, as with many similar experimental techniques, the outcome of Western blot analyses is easily influenced by choices made in the design and execution of the experiment. Specific housekeeping proteins have traditionally been used to normalize protein levels for quantification, however, these have a number of limitations and have therefore been increasingly criticized over the past few years. Here, we describe a detailed protocol that we have developed to allow us to undertake complex comparisons of protein expression variation across different tissues, mouse models (including disease models), and developmental timepoints. By using a fluorescent total protein stain and introducing the use of an internal loading standard, it is possible to overcome existing limitations in the number of samples that can be compared within experiments and systematically compare protein levels across a range of experimental conditions. This approach expands the use of traditional western blot techniques, thereby allowing researchers to better explore protein expression across different tissues and samples.

This method describes a robust and reproducible approach for the comparison of protein levels in different tissues and at different developmental timepoints using a standardized quantitative western blotting approach.

Western blotting is a technique that is commonly used to detect and quantify protein expression. Over the years, this technique has led to many advances ...

Biochemistry

Quantitative Whole-mount Immunofluorescence Analysis of Cardiac Progenitor Populations in Mouse Embryos

The use of ever-advancing imaging techniques has contributed broadly to our increased understanding of embryonic development. Pre-implantation development and organogenesis are two areas of research that have benefitted greatly from these advances, due to the high quality of data that can be obtained directly from imaging pre-implantation embryos or ex vivo organs. While pre-implantation embryos have yielded data with especially high spatial resolution, later stages have been less amenable to three-dimensional reconstruction. Obtaining high-quality 3D or volumetric data for known embryonic structures in combination with fate mapping or genetic lineage tracing will allow for a more comprehensive analysis of the morphogenetic events taking place during embryogenesis.
This protocol describes a whole-mount immunofluorescence approach that allows for the labeling, visualization, and quantification of progenitor cell populations within the developing cardiac crescent, a key structure formed during heart development. The approach is designed in such a way that both cell- and tissue-level information can be obtained. Using confocal microscopy and image processing, this protocol allows for three-dimensional spatial reconstruction of the cardiac crescent, thereby providing the ability to analyze the localization and organization of specific progenitor populations during this critical phase of heart development. Importantly, the use of reference antibodies allows for successive masking of the cardiac crescent and subsequent quantitative measurements of areas within the crescent. This protocol will not only enable a detailed examination of early heart development, but with adaptations should be applicable to most organ systems in the gastrula to early somite stage mouse embryo.

Here, we describe a protocol for whole mount immunofluorescence and image-based quantitative volumetric analysis of early stage mouse embryos. We present this technique as a powerful approach to qualitatively and quantitatively assess cardiac structures during development, and propose that it may be widely adaptable to other organ systems.

The use of ever-advancing imaging techniques has contributed broadly to our increased understanding of embryonic development. Pre-implantation development ...

Tracing Gene Expression Through Detection of &#946;-galactosidase Activity in Whole Mouse Embryos

The Escherichia coli LacZ gene, encoding &#946;-galactosidase, is largely used as a reporter for gene expression and as a tracer in cell lineage studies. The classical histochemical reaction is based on the hydrolysis of the substrate X-gal in combination with ferric and ferrous ions, which produces an insoluble blue precipitate that is easy to visualize. Therefore, &#946;-galactosidase activity serves as a marker for the expression pattern of the gene of interest as the development proceeds. Here we describe the standard protocol for the detection of &#946;-galactosidase activity in early whole mouse embryos and the subsequent method for paraffin sectioning and counterstaining. Additionally, a procedure for clarifying whole embryos is provided to better visualize X-gal staining in deeper regions of the embryo. Consistent results are obtained by performing this procedure, although optimization of reaction conditions is needed to minimize background activity. Limitations in the assay should be also considered, particularly regarding the size of the embryo in whole mount staining. Our protocol provides a sensitive and a reliable method for &#946;-galactosidase detection during the mouse development that can be further applied to the cryostat sections as well as whole organs. Thus, the dynamic gene expression patterns throughout development can be easily analyzed by using this protocol in whole embryos, but also detailed expression at the cellular level can be assessed after paraffin sectioning.

Here we describe the standard protocol for the detection of &#946;-galactosidase activity in early whole mouse embryos and the method for paraffin sectioning and counterstaining. This is an easy and quick procedure to monitor gene expression during development that can also be applied to tissue sections, organs or cultured cells.

The Escherichia coli LacZ gene, encoding &#946;-galactosidase, is largely used as a reporter for gene expression and as a tracer in cell lineage studies. ...

A Semi-high-throughput Imaging Method and Data Visualization Toolkit to Analyze C. elegans Embryonic Development

C. elegans is the premier system for the systematic analysis of cell fate specification and morphogenetic events during embryonic development. One challenge is that embryogenesis dynamically unfolds over a period of about 13 h; this half day-long timescale has constrained the scope of experiments by limiting the number of embryos that can be imaged. Here, we describe a semi-high-throughput protocol that allows for the simultaneous 3D time-lapse imaging of development in 80&#8211;100 embryos at moderate time resolution, from up to 14 different conditions, in a single overnight run. The protocol is straightforward and can be implemented by any laboratory with access to a microscope with point visiting capacity. The utility of this protocol is demonstrated by using it to image two custom-built strains expressing fluorescent markers optimized to visualize key aspects of germ-layer specification and morphogenesis. To analyze the data, a custom program that crops individual embryos out of a broader field of view in all channels, z-steps, and timepoints and saves the sequences for each embryo into a separate tiff stack was built. The program, which includes a user-friendly graphical user interface (GUI), streamlines data processing by isolating, pre-processing, and uniformly orienting individual embryos in preparation for visualization or automated analysis. Also supplied is an ImageJ macro that compiles individual embryo data into a multi-panel file that displays maximum intensity fluorescence projection and brightfield images for each embryo at each time point. The protocols and tools described herein were validated by using them to characterize embryonic development following knock-down of 40 previously described developmental genes; this analysis visualized previously annotated developmental phenotypes and revealed new ones. In summary, this work details a semi-high-throughput imaging method coupled with a cropping program and ImageJ visualization tool that, when combined with strains expressing informative fluorescent markers, greatly accelerates experiments to analyze embryonic development.

A Semi-high-throughput Imaging Method and Data Visualization Toolkit to Analyze C. elegans Embryonic Development

This work describes a semi-high-throughput protocol that allows simultaneous 3D time-lapse imaging of embryogenesis in 80&#8211;100 C. elegans embryos in a single overnight run. Additionally, image processing and visualization tools are included to streamline data analysis. The combination of these methods with custom reporter strains enables detailed monitoring of embryogenesis.

C. elegans is the premier system for the systematic analysis of cell fate specification and morphogenetic events during embryonic development. One ...

Multiplexed Single Cell mRNA Sequencing Analysis of Mouse Embryonic Cells

Single cell mRNA sequencing has made significant progress in the last several years and has become an important tool in the field of developmental biology. It has been successfully used to identify rare cell populations, discover novel marker genes, and decode spatial and temporal developmental information. The single cell method has also evolved from the microfluidic based Fluidigm C1 technology to the droplet-based solutions in the last two to three years. Here we used the heart as an example to demonstrate how to profile the mouse embryonic tissue cells using the droplet based scRNA-Seq method. In addition, we have integrated two strategies into the workflow to profile multiple samples in a single experiment. Using one of the integrated methods, we have simultaneously profiled more than 9,000 cells from eight heart samples. These methods will be valuable to the developmental biology field by providing a cost-effective way to simultaneously profile single cells from different genetic backgrounds, developmental stages, or anatomical locations.

Here we presented a multiplexed single cell mRNA sequencing method to profile gene expression in mouse embryonic tissues. The droplet-based single cell mRNA sequencing (scRNA-Seq) method in combination with multiplexing strategies can profile single cells from multiple samples simultaneously, which significantly reduces reagent costs and minimizes experimental batch effects.

Single cell mRNA sequencing has made significant progress in the last several years and has become an important tool in the field of developmental ...

Preparation of Small RNA Libraries for Sequencing from Early Mouse Embryos

MicroRNAs (miRNAs) are important for the complex regulation of cell fate decisions and developmental timing. In vivo studies of the contribution of miRNAs during early development are technically challenging due to the limiting cell number. Moreover, many approaches require a miRNA of interest to be defined in assays such as northern blotting, microarray, and qPCR. Therefore, the expression of many miRNAs and their isoforms have not been studied during early development. Here, we demonstrate a protocol for small RNA sequencing of sorted cells from early mouse embryos to enable relatively unbiased profiling of miRNAs in early populations of neural crest cells. We overcome the challenges of low cell input and size selection during library preparation using amplification and gel-based purification. We identify embryonic age as a variable accounting for variation between replicates and stage-matched mouse embryos must be used to accurately profile miRNAs in biological replicates. Our results suggest that this method can be broadly applied to profile the expression of miRNAs from other lineages of cells. In summary, this protocol can be used to study how miRNAs regulate developmental programs in different cell lineages of the early mouse embryo.

We describe a technique for profiling microRNAs in early mouse embryos. This protocol overcomes the challenge of low cell input and small RNA enrichment. This assay can be used to analyze changes in miRNA expression over time in different cell lineages of the early mouse embryo.

MicroRNAs (miRNAs) are important for the complex regulation of cell fate decisions and developmental timing. In vivo studies of the contribution of miRNAs ...

Cell-Lineage Guided Mass Spectrometry Proteomics in the Developing (Frog) Embryo

Characterization of molecular events as cells give rise to tissues and organs raises a potential to better understand normal development and design efficient remedies for diseases. Technologies enabling accurate identification and quantification of diverse types and large numbers of proteins would provide still missing information on molecular mechanisms orchestrating tissue and organism development in space and time. Here, we present a mass spectrometry-based protocol that enables the measurement of thousands of proteins in identified cell lineages in Xenopus laevis (frog) embryos. The approach builds on reproducible cell-fate maps and established methods to identify, fluorescently label, track, and sample cells and their progeny (clones) from this model of vertebrate development. After collecting cellular contents using microsampling or isolating cells by dissection or fluorescence-activated cell sorting, proteins are extracted and processed for bottom-up proteomic analysis. Liquid chromatography and capillary electrophoresis are used to provide scalable separation for protein detection and quantification with high-resolution mass spectrometry (HRMS). Representative examples are provided for the proteomic characterization of neural-tissue fated cells. Cell-lineage-guided HRMS proteomics is adaptable to different tissues and organisms. It is sufficiently sensitive, specific, and quantitative to peer into the spatio-temporal dynamics of the proteome during vertebrate development.

Cell-Lineage Guided Mass Spectrometry Proteomics in the Developing Frog Embryo

Here we describe a mass spectrometry-based proteomic characterization of cell lineages with known tissue fates in the vertebrate Xenopus laevis embryo.

Characterization of molecular events as cells give rise to tissues and organs raises a potential to better understand normal development and design ...

Chemistry

Chromatin Immunoprecipitation Assay for Tissue-specific Genes using Early-stage Mouse Embryos

Chromatin immunoprecipitation (ChIP) is a powerful tool to identify protein:chromatin interactions that occur in the context of living cells 1-3. This technique has been widely exploited in tissue culture cells, and to a lesser extent, in primary tissue. The application of ChIP to rodent embryonic tissue, especially at early times of development, is complicated by the limited amount of tissue and the heterogeneity of cell and tissue types in the embryo. Here we present a method to perform ChIP using a dissociated embryonic day 8.5 (E8.5) embryo. Sheared chromatin from a single E8.5 embryo can be divided into up to five aliquots, which allows the investigator sufficient material for controls and for investigation of specific protein:chromatin interactions.
We have utilized this technique to begin to document protein:chromatin interactions during the specification of tissue-specific gene expression programs. The heterogeneity of cell types in an embryo necessarily restricts the application of this technique because the result is the detection of protein:chromatin interactions without distinguishing whether the interactions occur in all, a subset of, or a single cell type(s). However, examination of tissue-specific genes during or following the onset of tissue-specific gene expression is feasible for two reasons. First, immunoprecipitation of tissue specific factors necessarily isolates chromatin from the cell type where the factor is expressed. Second, immunoprecipitation of coactivators and histones containing post-translational modifications that are associated with gene activation should only be found at genes and gene regulatory sequences in the cell type where the gene is being or has been activated. The technique should be applicable to the study of most tissue-specific gene activation events.
In the example described below, we utilized E8.5 and E9.5 mouse embryos to examine factor binding at a skeletal muscle specific gene promoter. Somites, which are the precursor tissues from which the skeletal muscles of the trunk and limbs will form, are present at E8.5-9.54,5. Myogenin is a regulatory factor required for skeletal muscle differentiation 6-9. The data demonstrate that myogenin is associated with its own promoter in E8.5 and E9.5 embryos. Because myogenin is only expressed in somites at this stage of development 6,10, the data indicate that myogenin interactions with its own promoter have already occurred in skeletal muscle precursor cells in E8.5 embryos.

We demonstrate a chromatin immunoprecipitation (ChIP) method to identify factor interactions at tissue-specific genes during or after the onset of tissue-specific gene expression in mouse embryonic tissue. This protocol should be widely applicable for the study of tissue-specific gene activation as it occurs during normal embryonic development.

Chromatin immunoprecipitation (ChIP) is a powerful tool to identify protein:chromatin interactions that occur in the context of living cells 1-3. This ...

Quantitative Analysis of Protein Expression to Study Lineage Specification in Mouse Preimplantation Embryos

Summary

Explore More Videos

Chapters in this video

Loss- and Gain-of-function Approach to Investigate Early Cell Fate Determinants in Preimplantation Mouse Embryos

Temporal Ordering of Dynamic Expression Data from Detailed Spatial Expression Maps

Robust Comparison of Protein Levels Across Tissues and Throughout Development Using Standardized Quantitative Western Blotting

Quantitative Whole-mount Immunofluorescence Analysis of Cardiac Progenitor Populations in Mouse Embryos

Tracing Gene Expression Through Detection of β-galactosidase Activity in Whole Mouse Embryos

A Semi-high-throughput Imaging Method and Data Visualization Toolkit to Analyze C. elegans Embryonic Development

Multiplexed Single Cell mRNA Sequencing Analysis of Mouse Embryonic Cells

Preparation of Small RNA Libraries for Sequencing from Early Mouse Embryos

Cell-Lineage Guided Mass Spectrometry Proteomics in the Developing (Frog) Embryo

Chromatin Immunoprecipitation Assay for Tissue-specific Genes using Early-stage Mouse Embryos