Name: prediction and validation of gene regulatory elements activated during retinoic acid induced embryonic stem cell differentiation
Uploaded: 2016-06-21T13:00:00
Description: Watch this Scientific Journal Video about Prediction and Validation of Gene Regulatory Elements Activated During Retinoic Acid Induced Embryonic Stem Cell Differentiation at JoVE.com

The authors would like to acknowledge Dr. Bence Daniel, Matt Peloquin, Dr. Endre Barta, Dr. Balint L Balint and members of the Nagy laboratory for discussions and comments on the manuscript. L.N is supported by grants from the Hungarian Scientific Research Fund (OTKA K100196 and K111941) and co-financed by the European Social Fund and the European Regional Development Fund and Hungarian Brain Research Program - Grant No. KTIA_13_NAP-A-I/9.

1. Enhancer Selection Based on Chip-seq Analysis
<ol>
	<li>Download the RXR ChIP-seq raw data fastq file (mm_ES_RXR_24h_ATRA.fastq.gz) from http://ngsdebftp.med.unideb.hu/bioinformatics/</li>
	<li>Download and extract the required BWA index file for the alignment (in our case: Mus_musculus_UCSC_mm10).(ftp://igenome:G3nom3s4u@ussd-ftp.illumina.com/Mus_musculus/UCSC/mm10/Mus_musculus_UCSC_mm10.tar.gz 
	NOTE: Visit to https://github.com/ahorvath/Bioinformatics_scripts for more information regarding the steps of bioin...

<ol>
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In recent years, advances in sequencing technology have allowed large-scale predictions of enhancers in many cell types and tissues 7-9. The workflow described above allows one to perform primary characterization of candidate enhancers chosen based on ChIP-seq data. The detailed steps and notes will help anyone to set up a routine enhancer validation in the lab.
The most critical step in the luciferase reporter assay is the transfection efficiency. It is recommended to include a GFP...

Development of a multicellular organism requires precisely regulated expression of thousands of genes across developing tissues. Regulation of gene expression is accomplished in large part by enhancers. Enhancers are short non-coding DNA elements that can be bound with transcription factors (TFs) and act from a distance to activate transcription of a target gene1. Enhancers are generally cis-acting and most frequently found just upstream of the transcription start site (TSS), but recent studies also described examples where enhancers were found much further upstream, on the 3' of the gene or even within the introns and exons2. 
There are hundreds of thousands of potential enhancers in the vertebrate genomes1. Recent methods based on chromatin immunoprecipitation (ChIP) provide high-throughput data of the whole genome that can be used for enhancer analysis3-9. Though data obtained by ChIP-seq experiments greatly increases the likelihood to identify cell and tissue-specific enhancers, it is important to keep in mind that detected binding sites do not necessarily identify direct DNA binding and/or functional enhancers. Thus, further functional analysis of newly identified enhancers is indispensable. In this work, we present a basic three-step process of putative active enhancer identification and validation. This includes: 1) selection of putative transcription factor binding sites by bioinformatics analysis of ChIP-seq data, 2) cloning and validation of these regulatory sequences in reporter constructs, and 3) measurement of enhancer RNA (eRNA). 
Exposure of embryonic stem (ES) cells to retinoic acid (RA) is frequently used to promote neural differentiation of the pluripotent cells 10. RA exerts its effects by binding to RA receptors (RAR&#945;, &#946;, &#947;) and retinoid X receptors (RXR&#945;, &#946;, &#947;). RARs and RXRs in a form of heterodimer bind to DNA motifs called RA-response elements, that is typically arranged as direct repeats of AGGTCA sequence (called as half site) and regulate transcription. Ligand-treatment experiments allowed the identification of several retinoic acid regulated genes in ES cells 11,12. However, enhancer elements for many of these genes has not been described yet. To demonstrate how the here-described workflow can be used for enhancer identification and validation we show step-by-step the selection and characterization of two retinoic acid-dependent enhancers in embryonic stem cells.

<table border="0" cellpadding="0" cellspacing="0" width="862">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">KOD DNA polymerase</td>
			<td style="width:121px;">Merck Millipore</td>
			<td style="width:119px;">71085-3</td>
			<td style="width:323px;">for PCR amplification of enhancer from gDNA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DNeasy Blood &#38; Tissue kit&#160;</td>
			<td>Qiagen</td>
			<td>69504</td>
			<td>for genomic DNA isolation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">QIAquick PCR Purification kit</td>
			<td>Qiagen</td>
			<td>28106</td>
			<td>for PCR product purification</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gel extraction kit&#160;</td>
			<td>Qiagen</td>
			<td>28706</td>
			<td>for gel extraction if there are more PCR product</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HindIII</td>
			<td style="width:121px;">NEB</td>
			<td>R3104L</td>
			<td>restriction enzyme</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BamHI</td>
			<td style="width:121px;">NEB</td>
			<td>R3136L</td>
			<td>restriction enzyme</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FastAP</td>
			<td>Thermo Scientific</td>
			<td>EF0651</td>
			<td>release of 5&#39;- and 3&#39;-phosphate groups from DNA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">T4 DNA ligase</td>
			<td style="width:121px;">NEB</td>
			<td>M0202</td>
			<td>for ligation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">QIAprep Spin Miniprep kit</td>
			<td>Qiagen</td>
			<td>27106</td>
			<td>for plasmid isolation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">DMEM</td>
			<td style="width:121px;">Gibco</td>
			<td style="width:119px;">31966-021</td>
			<td>ES media</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">FBS</td>
			<td style="width:121px;">Hyclone</td>
			<td style="width:119px;">SH30070.03</td>
			<td>ES media</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">MEM Non-Essential Amino Acid</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">M7145</td>
			<td>ES media</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">Penicillin-Streptomycin</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">P4333</td>
			<td>ES media</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">Beta Mercaptoethanol</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">M6250</td>
			<td>ES media</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FuGENE HD&#160;</td>
			<td style="width:121px;">Promega</td>
			<td style="width:119px;">E2311</td>
			<td>transfection reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">Opti-MEM&#174; I Reduced Serum Medium</td>
			<td>Life Technologies</td>
			<td style="width:119px;">31985-062</td>
			<td>for transfection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">All-trans retinoic acid</td>
			<td style="width:121px;">Sigma</td>
			<td>R2625</td>
			<td>ligand, for activation of RAR/RXR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">96-well clear plate</td>
			<td style="width:121px;">Greiner</td>
			<td>655101</td>
			<td>for Beta galactosidase assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">96-well white plate</td>
			<td style="width:121px;">Greiner</td>
			<td>655075</td>
			<td>for Luciferase assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">D-luciferin, potassium salt</td>
			<td style="width:121px;">Goldbio.com</td>
			<td style="width:119px;">115144-35-9</td>
			<td>for Luciferase assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ATP salt</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">A7699-1G</td>
			<td>for Luciferase assay</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">MgSO4x 7H2O</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">230391-25G</td>
			<td>for Luciferase assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">HEPES</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">H3375-25G</td>
			<td>for Luciferase assay</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Na2HPO4 x 7H2O</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">431478-50G</td>
			<td>for Beta galactosidase assay</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">NaH2PO4 x H2O</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">S9638-25G</td>
			<td>for Beta galactosidase assay</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">MgSO4 x 7H2O</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">230391-25G</td>
			<td>for Beta galactosidase assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">KCl</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">P9541-500G</td>
			<td>for Beta galactosidase assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ONPG (o-nitrophenyl-&#946;-D-galactosidase)</td>
			<td style="width:121px;">Sigma</td>
			<td style="width:119px;">N1127-1G</td>
			<td>for Beta galactosidase assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TRIzol&#174;</td>
			<td>Life Technologies</td>
			<td>15596-026</td>
			<td>RNA isolation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">High-Capacity cDNA Reverse Transcription Kit</td>
			<td>Life Technologies</td>
			<td>4368814</td>
			<td>reverse transcription of eRNA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">Rnase-free Dnase</td>
			<td style="width:121px;">Promega</td>
			<td>M6101</td>
			<td>Dnase treatment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">SsoFast Eva Green</td>
			<td style="width:121px;">BioRad</td>
			<td style="width:119px;">750000105</td>
			<td>RT-qPCR mastermix</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:300px;">CFX384 Touch&#8482; Real-Time PCR Detection System</td>
			<td style="width:121px;">BioRad</td>
			<td style="width:119px;"></td>
			<td>qPCR machine</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">BioTek Synergy 4 microplate reader</td>
			<td style="width:121px;">BioTek</td>
			<td style="width:119px;"></td>
			<td>luminescent counter</td>
		</tr>
	</tbody>
</table>

prediction and validation of gene regulatory elements activated during retinoic acid induced embryonic stem cell differentiation

Embryonic development is a multistep process involving activation and repression of many genes. Enhancer elements in the genome are known to contribute to tissue and cell-type specific regulation of gene expression during the cellular differentiation. Thus, their identification and further investigation is important in order to understand how cell fate is determined. Integration of gene expression data (e.g., microarray or RNA-seq) and results of chromatin immunoprecipitation (ChIP)-based genome-wide studies (ChIP-seq) allows large-scale identification of these regulatory regions. However, functional validation of cell-type specific enhancers requires further in vitro and in vivo experimental procedures. Here we describe how active enhancers can be identified and validated experimentally. This protocol provides a step-by-step workflow that includes: 1) identification of regulatory regions by ChIP-seq data analysis, 2) cloning and experimental validation of putative regulatory potential of the identified genomic sequences in a reporter assay, and 3) determination of enhancer activity in vivo by measuring enhancer RNA transcript level. The presented protocol is detailed enough to help anyone to set up this workflow in the lab. Importantly, the protocol can be easily adapted to and used in any cellular model system.

We used a pan-specific RXR antibody in order to identify genome-wide which RA-regulated genes have receptor enrichment in their close proximity. Bioinformatics analysis of RXR ChIP-seq data obtained from ES cells treated with retinoic acid revealed the enrichment of the nuclear receptor half site (AGGTCA) under the RXR occupied sites (Figure 1). Using a bioinformatics algorithm we mapped back the motif search result for the half site to the RXR ChIP-seq data (Figu...

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Prediction and Validation of Gene Regulatory Elements Activated During Retinoic Acid Induced Embryonic Stem Cell Differentiation

In this work we provide an experimental workflow of how active enhancers can be identified and experimentally validated.

Embryonic development is a multistep process involving activation and repression of many genes. Enhancer elements in the genome are known to contribute to ...

The overall goal of this video is to provide an integrated set of methods to identify and experimentally validate geneomic regulatory elements so called enhancers. This method can help answer key questions in the transcription and regulation of biologic events, including enhancer selection and usage, using cell differentiation, or in response to external stimuli. The main advantage to the presented work-flow is that a protocol can be easily adapted and used in any cellular model systems.I will demonstrate the steps of the procedure. To begin, choose a candidate enhancer based on pre-existing chip seq analysis. Use a genome browser to view the results of the desired chip seq experiment, and identify binding sites in the proximity of the gene of interest.Choose Define a Region of Interest to obtain a 200-400 base pair sequence of the selected genomic region, and use the sequences for subsequent primer design. With standard molecular biology techniques, amplify and clone the selected genomic region into a reporter plasmid construct. To test enhancer activity, transfect the reporter constructs into mass embryonic stem cells by first adding 200 micro liters of 0.1%gelatin solution per well to 48 well plates.Incubate the plates for 30 minutes prior to plating. The day before transfection, plate feeder-free embryonic stem, or ES cells, in 250 micro liters of ES medium at a density of three times 10 to the fourth cells per well. On the day of transfection, prepare the plasmid mixes, making enough for eight wells from each mix.Add transfection quality reduced serum medium to each plasmid mix to bring the volume up to 106 micro liters. Then, add 4.5 micro liters of ES quality transfection reagent, and carefully mix by pipetting 15 times up and down. Incubate the transfection mix for 15 minutes at room temperature.After the incubation, add 13 micro liters per well of the transfection mix to the cells and mix thoroughly by pipetting. Then, place the cells back into the incubator over night before lichen treatment. Transfection efficiency is a critical step.If another cell type is used, this step requires optimization. Use the most relevant cell type to test enhancer activity to minimize the context-dependent effects. The following day, carefully remove the medium by aspiration, and add 250 micro liters of fresh medium per well containing one micro molar all trans retinoic acid, or DMSO as a vehicle.Incubate the cells for 24-48 hours. After preparing lysis buffer according to the text protocol, carefully aspirate the medium from the cells. Use 1X PBS to rise the cells once, then add 200 micro liters of 1X lysis buffer per well.Shake the cells at room temperature for two hours. Then, for complete cell lysis, freeze the cell lysates in the plate at 80 degrees Celsius. After completely thawing the lysates, use an electronic multi-channel pipet to transfer 80 micro liters of the cell lysate to 96 well clear plate for the beta galactosidase, and 40 micro liters of the lysate to a white plate for luciferase measurement.To carry out the beta galactosidase, mix one milliliter of the beta gal substrate buffer with four milligrams of OMPG. Then, add 3.5 micro liters of beta mercaptoethanol to the mixture and immediately add 100 micro liters of the buffer to the 80 micro liters of cell lysate. Incubate the reactions at 37 degrees Celsius until the faint yellow color develops.Read the absorbence at 420 nano meters on a plate reader, and export the data. To perform the luciferase assay, after preparing the substrate reagent according to the text protocol, warm the luciferase substrate reagent to room temperature before starting. Then, pipet 100 micro liters into each well of the white plate containing the 40 micro liters of cell lysate.Immediately use a luminescent counter machine to measure the signal. Obtain the activities from at least three independent transfections and experiments. Perform calculates for both assays according to the text protocol.To design the primers for eRNA detection by RTCPR, select a genomic region that is at least 1.5 to two kilo bases away from any annotated gene transcripts. Identify the relative direction of the gene, and determine the position of the sense and anti-sense transcripts. To design primers for the enhancer RNA quantification, choose regions 200-1, 000 base pairs from the center of the transcription factor binding site.If the gene is located on the minus strand, copy 200-300 base pairs of the positive strand and convert the sequence to get the reverse complement sequence. Then, use this sequence for subsequent primer design. Set the Product Size Range between 80-150 base pairs.To measure eRNA transcription, after isolating total RNA from treated cells according to the text protocol, detect reverse transcribed eRNA by RTCPR using a standard procedure. Measure a non-treatment dependent mRNA for normalization. As shown here, bioinformatics analysis of RXR chip seq data obtained from ES cells treated with retinoic acid revealed the enrichment of the nuclear receptor half site under the RXR occupied sites.Using a bioinformatics algorithm, the motif search results for the half-site was mapped back to the RXR chip seq data. This analysis identified chip peaks overlapping with canonical nuclear receptor binding sites. Visualization of the sites in IGV indicated enrichment of the transcription factors close to Hoxa1.A previously characterized RAR RXR target. A punitive enhancer for a novel RA target chain, PRMT8, was also identified. The identified enhancer regions were cloned into TK luciferase reporter vector, and ES cells were transfected with these constructs.Luciferase activity was measured in the absence and presence of RA.The constructs containing the RA response element, or RARE, showed increased luciferase signal intensity upon RA treatment, while the construct without the RARE was not induced. To ascertain if the sense and anti-sense eRNA expression of the Hoxa1 RAR RXR bound enhancer correlates with the mRNA expression of the gene, the level of Hoxa1 eRNA was also measured. The results confirmed that the enhancer activity is induced by short term RA treatment.Once mastered, this workload can be done in a few days by carrying out the described enhancer trap experiment and enhancer quantification, one can provide strong functional evidence for enhancer activity. After watching this video, you should have a good understanding of how to identify and characterize punitive enhancers. Once an enhancer is identified and validated, other methods, such as chromosomal confirmation capture, or CCC, can be performed in order to answer additional important questions, like which gene is regulated by the validated enhancer?

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Developmental Biology

Derivation of Highly Purified Cardiomyocytes from Human Induced Pluripotent Stem Cells Using Small Molecule-modulated Differentiation and Subsequent Glucose Starvation

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have become an important cell source to address the lack of primary cardiomyocytes available for basic research and translational applications. To differentiate hiPSCs into cardiomyocytes, various protocols including embryoid body (EB)-based differentiation and growth factor induction have been developed. However, these protocols are inefficient and highly variable in their ability to generate purified cardiomyocytes. Recently, a small molecule-based protocol utilizing modulation of Wnt/&#946;-Catenin signaling was shown to promote cardiac differentiation with high efficiency. With this protocol, greater than 50%-60% of differentiated cells were cardiac troponin-positive cardiomyocytes were consistently observed. To further increase cardiomyocyte purity, the differentiated cells were subjected to glucose starvation to specifically eliminate non-cardiomyocytes based on the metabolic differences between cardiomyocytes and non-cardiomyocytes. Using this selection strategy, we consistently obtained a greater than 30% increase in the ratio of cardiomyocytes to non-cardiomyocytes in a population of differentiated cells. These highly purified cardiomyocytes should enhance the reliability of results from human iPSC-based in vitro disease modeling studies and drug screening assays.

Here, we describe a robust protocol for human cardiomyocyte derivation that combines small molecule-modulated cardiac differentiation and glucose deprivation-mediated cardiomyocyte purification, enabling production of purified cardiomyocytes for the purposes of cardiovascular disease modeling and drug screening.

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have become an important cell source to address the lack of primary cardiomyocytes ...

Neural Differentiation of Mouse Embryonic Stem Cells in Serum-free Monolayer Culture

The ability to differentiate mouse embryonic stem cells (ESC) to neural progenitors allows the study of the mechanisms controlling neural specification as well as the generation of mature neural cell types for further study. In this protocol we describe a method for the differentiation of ESC to neural progenitors using serum-free, monolayer culture. The method is scalable, efficient and results in production of ~70% neural progenitor cells within 4 - 6 days. It can be applied to ESC from various strains grown under a variety of conditions. Neural progenitors can be allowed to differentiate further into functional neurons and glia or analyzed by microscopy, flow cytometry or molecular techniques. The differentiation process is amenable to time-lapse microscopy and can be combined with the use of reporter lines to monitor the neural specification process. We provide detailed instructions on media preparation and cell density optimization to allow the process to be applied to most ESC lines and a variety of cell culture vessels.

This protocol describes in detail the method for generating neural progenitors from embryonic stem cells using a serum-free monolayer method. These progenitors can be used to derive mature neural cell types or to study the process of neural specification and is amenable to multiwell format scaling for compound screening.

The ability to differentiate mouse embryonic stem cells (ESC) to neural progenitors allows the study of the mechanisms controlling neural specification as ...

Epigenetic Regulation of Cardiac Differentiation of Embryonic Stem Cells and Tissues

Specific gene transcription is a key biological process that underlies cell fate decision during embryonic development. The biological process is mediated by transcription factors which bind genomic regulatory regions including enhancers and promoters of cardiac constitutive genes. DNA is wrapped around histones that are subjected to chemical modifications. Modifications of histones further lead to repressed, activated or poised gene transcription, thus bringing another level of fine tuning regulation of gene transcription. Embryonic Stem cells (ES cells) recapitulate within embryoid bodies (i.e., cell aggregates) or in 2D culture the early steps of cardiac development. They provide in principle enough material for chromatin immunoprecipitation (ChIP), a technology broadly used to identify gene regulatory regions. Furthermore, human ES cells represent a human cell model of cardiogenesis. At later stages of development, mouse embryonic tissues allow for investigating specific epigenetic landscapes required for determination of cell identity. Herein, we describe protocols of ChIP, sequential ChIP followed by PCR or ChIP-sequencing using ES cells, embryoid bodies and cardiac specific embryonic regions. These protocols allow to investigating the epigenetic regulation of cardiac gene transcription.

A fine tuning regulation of gene transcription underlies embryonic cell fate decision. Herein, we describe chromatin immunoprecipitation assays used to investigate epigenetic regulation of both cardiac differentiation of stem cells and cardiac development of mouse embryos.

Specific gene transcription is a key biological process that underlies cell fate decision during embryonic development. The biological process is mediated ...

Analysis of Retinoic Acid-induced Neural Differentiation of Mouse Embryonic Stem Cells in Two and Three-dimensional Embryoid Bodies

Mouse embryonic stem cells (ESCs) isolated from the inner mass of the blastocyst (typically at day E3.5), can be used as in vitro model system for studying early embryonic development. In the absence of leukemia inhibitory factor (LIF), ESCs differentiate by default into neural precursor cells. They can be amassed into a three dimensional (3D) spherical aggregate termed embryoid body (EB) due to its similarity to the early stage embryo. EBs can be seeded on fibronectin-coated coverslips, where they expand by growing two dimensional (2D) extensions, or implanted in 3D collagen matrices where they continue growing as spheroids, and differentiate into the three germ layers: endodermal, mesodermal, and ectodermal. The 3D collagen culture mimics the in vivo environment more closely than the 2D EBs. The 2D EB culture facilitates analysis by immunofluorescence and immunoblotting to track differentiation. We have developed a two-step neural differentiation protocol. In the first step, EBs are generated by the hanging-drop technique, and, simultaneously, are induced to differentiate by exposure to retinoic acid (RA). In the second step, neural differentiation proceeds in a 2D or 3D format in the absence of RA.

We describe a technique for using murine embryonic stem cells for generating two or three dimensional embryoid bodies. We then explain how to induce neural differentiation of the embryoid body cells by retinoic acid, and how to analyze their state of differentiation by progenitor cell marker immunofluorescence and immunoblotting.

Mouse embryonic stem cells (ESCs) isolated from the inner mass of the blastocyst (typically at day E3.5), can be used as in vitro model system for ...

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development

Kinase activity is crucial for a plethora of cellular functions, including cell proliferation, differentiation, migration, and apoptosis. During early embryonic development, kinase activity is highly dynamic and widespread across the embryo. Pharmacological and genetic approaches are commonly used to probe kinase activities. Unfortunately, it is challenging to achieve superior spatial and temporal resolution using these strategies. Furthermore, it is not feasible to control the kinase activity in a reversible fashion in live cells and multicellular organisms. Such a limitation remains a bottleneck for achieving a quantitative understanding of kinase activity during development and differentiation. This work presents an optogenetic strategy that takes advantage of a bicistronic system containing photoactivatable proteins Arabidopsis thaliana cryptochrome 2 (CRY2) and the N-terminal domain of cryptochrome-interacting basic-helix-loop-helix (CIBN). Reversible activation of the mitogen-activated protein kinase (MAPK) signaling pathway is achieved through light-mediated protein translocation in live cells. This approach can be applied to mammalian cell cultures and live vertebrate embryos. This bicistronic system can be generalized to control the activity of other kinases with similar activation mechanisms and can be applied to other model systems.

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development

This protocol describes an optogenetic strategy to modulate mitogen-activated protein kinase (MAPK) activity during cell differentiation and Xenopus embryonic development. This method allows for the reversible activation of the MAPK signaling pathway in mammalian cell culture and in multicellular live organisms, like Xenopus embryos, with high spatial and temporal resolution.

Kinase activity is crucial for a plethora of cellular functions, including cell proliferation, differentiation, migration, and apoptosis. During early ...

Rapid, Directed Differentiation of Retinal Pigment Epithelial Cells from Human Embryonic or Induced Pluripotent Stem Cells

We describe a robust method to direct the differentiation of pluripotent stem cells into retinal pigment epithelial cells (RPE). The purpose of providing a detailed and thorough protocol is to clearly demonstrate each step and to make this readily available to researchers in the field. This protocol results in a homogenous layer of RPE with minimal or no manual dissection needed. The method presented here has been shown to be effective for induced pluripotent stem cells (iPSC) and human embryonic stem cells. Additionally, we describe methods for cryopreservation of intermediate cell banks that allow long-term storage. RPE generated using this protocol might be useful for iPSC disease-in-a-dish modeling or clinical application.

This protocol describes how to produce retinal pigment epithelial cells (RPE) from pluripotent stem cells. The method uses a combination of growth factors and small molecules to direct the differentiation of stem cells into immature RPE in fourteen days and mature, functional RPE after three months.

We describe a robust method to direct the differentiation of pluripotent stem cells into retinal pigment epithelial cells (RPE). The purpose of providing ...

Live Cell Imaging of Chromosome Segregation During Mitosis

Chromosomes must be reliably and uniformly segregated into daughter cells during mitotic cell division. Fidelity of chromosomal segregation is controlled by multiple mechanisms that include the Spindle Assembly Checkpoint (SAC). The SAC is part of a complex feedback system that is responsible for prevention of a cell progress through mitosis unless all chromosomal kinetochores have attached to spindle microtubules. Chromosomal lagging and abnormal chromosome segregation is an indicator of dysfunctional cell cycle control checkpoints and can be used to measure the genomic stability of dividing cells. Deregulation of the SAC can result in the transformation of a normal cell into a malignant cell through the accumulation of errors during chromosomal segregation. Implementation of the SAC and the formation of the kinetochore complex are tightly regulated by interactions between kinases and phosphatase such as Protein Phosphatase 2A (PP2A). This protocol describes live cell imaging of lagging chromosomes in mouse embryonic fibroblasts isolated from mice that had a knockout of the PP2A-B56&#947; regulatory subunit. This method overcomes the shortcomings of other cell cycle control imaging techniques such as flow cytometry or immunocytochemistry that only provide a snapshot of a cell cytokinesis status, instead of a dynamic spatiotemporal visualization of chromosomes during mitosis.

This protocol describes an easy and convenient method to label and visualize live chromosomes in mitotic cells using Histone2B-GFP BacMam 2.0 label and a spinning disc confocal microscopy system.

Chromosomes must be reliably and uniformly segregated into daughter cells during mitotic cell division. Fidelity of chromosomal segregation is controlled ...

Efficient Differentiation of Human Pluripotent Stem Cells into Liver Cells

The liver detoxifies harmful substances, secretes vital proteins, and executes key metabolic activities, thus sustaining life. Consequently, liver failure&#8212;which can be caused by chronic alcohol intake, hepatitis, acute poisoning, or other insults&#8212;is a severe condition that can culminate in bleeding, jaundice, coma, and eventually death. However, approaches to treat liver failure, as well as studies of liver function and disease, have been stymied in part by the lack of a plentiful supply of human liver cells. To this end, this protocol details the efficient differentiation of human pluripotent stem cells (hPSCs) into hepatocyte-like cells, guided by a developmental roadmap that describes how liver fate is specified across six consecutive differentiation steps. By manipulating developmental signaling pathways to promote liver differentiation and to explicitly suppress the formation of unwanted cell fates, this method efficiently generates populations of human liver bud progenitors and hepatocyte-like cells by days 6 and 18 of PSC differentiation, respectively. This is achieved through the temporally-precise control of developmental signaling pathways, exerted by small molecules and growth factors in a serum-free culture medium. Differentiation in this system occurs in monolayers and yields hepatocyte-like cells that express characteristic hepatocyte enzymes and have the ability to engraft a mouse model of chronic liver failure. The ability to efficiently generate large numbers of human liver cells in vitro has ramifications for treatment of liver failure, for drug screening, and for mechanistic studies of liver disease.

This protocol details a monolayer, serum-free method to efficiently generate hepatocyte-like cells from human pluripotent stem cells (hPSCs) in 18 days. This entails six steps as hPSCs sequentially differentiate into intermediate cell-types such as the primitive streak, definitive endoderm, posterior foregut and liver bud progenitors before forming hepatocyte-like cells.

The liver detoxifies harmful substances, secretes vital proteins, and executes key metabolic activities, thus sustaining life. Consequently, liver ...

Isolation, Propagation, and Prion Protein Expression During Neuronal Differentiation of Human Dental Pulp Stem Cells

Bioethical issues related to the manipulation of embryonic stem cells have hindered advances in the field of medical research. For this reason, it is very important to obtain adult stem cells from different tissues such as adipose, umbilical cord, bone marrow and blood. Among the possible sources, dental pulp is particularly interesting because it is easy to obtain in respect of bioethical considerations. Indeed, human Dental Pulp Stem Cells (hDPSCs) are a type of adult stem cells able to differentiate in neuronal-like cells and can be obtained from the third molar of healthy patients (13-19 ages). In particular, the dental pulp was removed with an excavator, cut into small slices, treated with collagenase IV and cultured in a flask. To induce the neuronal differentiation, hDPSCs were stimulated with EGF/bFGF for 2 weeks. Previously, we have demonstrated that during the differentiation process the content of cellular prion Protein (PrPC) in hDPSCs increased. The cytofluorimetric analysis showed an early expression of PrPC that increased after neuronal differentiation process. Ablation of PrPC by siRNA PrP prevented neuronal differentiation induced by EGF/bFGF. In this paper, we illustrate that as we enhanced the isolation, separation and in vitro cultivation methods of hDPSCs with several easy procedures, more efficient cell clones were obtained and large-scale expansion of the mesenchymal stem cells (MSCs) was observed. We also show how the hDPSCs, obtained with methods detailed in the protocol, are an excellent experimental model to study the neuronal differentiation process of MSCs and subsequent cellular and molecular processes.

Here we present a protocol for human Dental Pulp Stem Cells isolation and propagation in order to evaluate the prion protein expression during neuronal differentiation process.

Bioethical issues related to the manipulation of embryonic stem cells have hindered advances in the field of medical research. For this reason, it is very ...

Analysis of Cardiac Chamber Development During Mouse Embryogenesis Using Whole Mount Epifluorescence

The goal of this protocol is to describe a method for the dissection of mouse embryos and visualization of embryonic mouse ventricular chambers during heart development using ventricular specific fluorescent reporter knock-in mice (MLC-2v-tdTomato mice). Heart development involves a linear heart tube formation, the heart tube looping, and four chamber septation. These complex processes are highly conserved in all vertebrates. The mouse embryonic heart has been widely used for heart developmental studies. However, due to their extremely small size, dissecting mouse embryonic hearts is technically challenging. In addition, visualization of cardiac chamber formation often needs in situ hybridization, beta-galactosidase staining using LacZ reporter mice, or immunostaining of sectioned embryonic hearts. Here, we describe how to dissect mouse embryonic hearts and directly visualize ventricular chamber formation of MLC-2v-tdTomato mice using whole mount epifluorescent microscopy. With this method, it is possible to directly examine heart tube formation and looping, and four chamber formation without further experimental manipulation of mouse embryos. Although the MLC-2v-tdTomato reporter knock-in mouse line is used in this protocol as an example, this protocol can be applied to other heart-specific fluorescent reporter transgenic mouse lines.

We present the protocols to examine mouse heart development using whole mount epifluorescent microscopy on mouse embryos dissected from ventricular specific MLC-2v-tdTomato reporter knock-in mice. This method allows us to directly visualize each stage of the ventricular formation during mouse heart development without labor-intensive histochemical methods.

The goal of this protocol is to describe a method for the dissection of mouse embryos and visualization of embryonic mouse ventricular chambers during ...