Name: single-cell rna sequencing of fluorescently labeled mouse neurons using manual sorting and double in vitro transcription with absolute counts sequencing (diva-seq)
Uploaded: 2018-10-26T15:00:00
Description: Watch this Scientific Journal Video about Single-cell RNA Sequencing of Fluorescently Labeled Mouse Neurons Using Manual Sorting and Double In Vitro Transcription with Absolute Counts Sequencing DIVA-

This work was supported by grants from the NIH (5R01MH094705-04 and R01MH109665-01 to Z.J.H.), by the CSHL Robertson Neuroscience Fund (to Z.J.H.), and by a NARSAD Post-Doctoral Fellowship (to A.P.).

All the procedures including animal subjects have been approved by IACUC at Cold Spring Harbor Laboratory, NY (IACUC #16-13-09-8).
1. Manual Sorting of Fluorescently Labeled Mouse Neurons
<ol>
	<li>Pull glass microcapillaries (see Table of Materials) to 10&#8211;15 &#181;m exit diameter using a capillary puller with the following settings: heat: 508, pull: blank, vel: blank, time: blank.</li>
	<li>Attach 120&#8211;150 cm flexible silicone tubing (~0.8 mm inside diameter) to ...

<ol>
	<li>Macosko, E. Z., 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=Highly+Parallel+Genome-wide+Expression+Profiling+of+Individual+Cells+Using+Nanoliter+Droplets.">Highly Parallel Genome-wide Expression Profiling of Individual Cells Using Nanoliter Droplets.</a> Cell. 161 (5), 1202-1214 (2015).</li><li>Klein, A. 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=Droplet+barcoding+for+single-cell+transcriptomics+applied+to+embryonic+stem+cells.">Droplet barcoding for single-cell transcriptomics applied to embryonic stem cells.</a> Cell. 161 (5), 1187-1201 (2015).</li><li>Xin, 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=Use+of+the+Fluidigm+C1+platform+for+RNA+sequencing+of+single+mouse+pancreatic+islet+cells.">Use of the Fluidigm C1 platform for RNA sequencing of single mouse pancreatic islet cells.</a> Proceedings of the National Academy of Sciences of the United States of America. 113 (12), 3293-3298 (2016).</li><li>Gao, R., 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=Nanogrid+single-nucleus+RNA+sequencing+reveals+phenotypic+diversity+in+breast+cancer.">Nanogrid single-nucleus RNA sequencing reveals phenotypic diversity in breast cancer.</a> Nature Communications. 8 (1), 228 (2017).</li><li>Yuan, J., Sims, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Automated+Microwell+Platform+for+Large-Scale+Single+Cell+RNA-Seq.">An Automated Microwell Platform for Large-Scale Single Cell RNA-Seq.</a> Scientific Reports. 6, 33883 (2016).</li><li>Eberwine, 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=Analysis+of+gene+expression+in+single+live+neurons.">Analysis of gene expression in single live neurons.</a> Proceedings of the National Academy of Sciences of the United States of America. 89 (7), 3010-3014 (1992).</li><li>Hashimshony, T., Wagner, F., Sher, N., Yanai, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CEL-Seq:+Single-Cell+RNA-Seq+by+Multiplexed+Linear+Amplification.">CEL-Seq: Single-Cell RNA-Seq by Multiplexed Linear Amplification.</a> Cell Reports. 2 (3), 666-673 (2012).</li><li>Paul, 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=Transcriptional+Architecture+of+Synaptic+Communication+Delineates+GABAergic+Neuron+Identity.">Transcriptional Architecture of Synaptic Communication Delineates GABAergic Neuron Identity.</a> Cell. 171 (3), 522-539 (2017).</li><li>Zeisel, 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=Cell+types+in+the+mouse+cortex+and+hippocampus+revealed+by+single-cell+RNA-seq.">Cell types in the mouse cortex and hippocampus revealed by single-cell RNA-seq.</a> Science. 1934, (2015).</li><li>Tasic, B., 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=Adult+mouse+cortical+cell+taxonomy+revealed+by+single+cell+transcriptomics.">Adult mouse cortical cell taxonomy revealed by single cell transcriptomics.</a> Nature Neuroscience. 19, 335-346 (2016).</li><li>Okaty, B. W., 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=Multi-Scale+Molecular+Deconstruction+of+the+Serotonin+Neuron+System.">Multi-Scale Molecular Deconstruction of the Serotonin Neuron System.</a> Neuron. 88 (4), 774-791 (2015).</li><li>Poulin, J. F., Tasic, B., Hjerling-Leffler, J., Trimarchi, J. M., Awatramani, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disentangling+neural+cell+diversity+using+single-cell+transcriptomics.">Disentangling neural cell diversity using single-cell transcriptomics.</a> Nature Neuroscience. 19 (9), 1131-1141 (2016).</li><li>Crow, M., Paul, A., Ballouz, S., Huang, Z. J., Gillis, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exploiting+single-cell+expression+to+characterize+co-expression+replicability.">Exploiting single-cell expression to characterize co-expression replicability.</a> Genome Biology. 17, 101 (2016).</li><li>Crow, M., Paul, A., Ballouz, S., Huang, Z. J., Gillis, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterizing+the+replicability+of+cell+types+defined+by+single+cell+RNA-sequencing+data+using+MetaNeighbor.">Characterizing the replicability of cell types defined by single cell RNA-sequencing data using MetaNeighbor.</a> Nature Communications. 9 (1), (2018).</li><li>Hrvatin, 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=Single-cell+analysis+of+experience-dependent+transcriptomic+states+in+the+mouse+visual+cortex.">Single-cell analysis of experience-dependent transcriptomic states in the mouse visual cortex.</a> Nature Neuroscience. 21 (1), 120-129 (2018).</li></ol>

The manual sorting protocol is suitable for a supervised RNA sequencing of neuron populations that are either sparsely labeled in the mice brain or are representing a rare cell population that is otherwise not feasible to study using current high-throughput cell sorting and amplification methods. Cells subjected to FACS usually undergo sheath and sample line pressures in the range of ~9&#8211;14 psi, depending on nozzle size and desired event rates. In addition, upon being ejected from the nozzle, the cells can land hard...

Single-cell RNA sequencing (RNA-seq) has transformed transcriptomic studies. While large-scale single-cell RNAseq can be performed using a variety of techniques, such as droplets1,2, microfluidics3, nanogrids4, and microwells5, most methods cannot sort defined cell types that express genetically encoded fluorophores. To isolate a select cell population, fluorescence-activated cell sorting (FACS) is often used to sort labeled cells in a single-cell mode. However, FACS has some restrictions and requires meticulous sample processing steps. First, a large number of input cells are typically needed (often several million cells per mL), with a significant fraction (&#62;15&#8211;20%) containing the labeled population. Second, cell preparations may require multiple rounds of density gradient centrifugation steps to remove glial fraction, debris, and cell clumps that might otherwise clog the nozzle or flow cell. Third, FACS usually employs staining and destaining steps for live/dead staining (e.g., 4&#8242;,6-diamidino-2-phenylindole (DAPI), propidium iodide (PI), and Cytotracker dyes), which take up additional time. Fourth, as a rule of thumb for two-color sorting (such as DAPI and green/red fluorescent protein (GFP/RFP)), usually two samples and one control are needed, requiring an unlabeled sample to be processed in addition to the desired mouse strain. Fifth, filtering is often performed multiple times before and during sample sorting to proactively prevent clogged sample lines in an FACS machine. Sixth, time must be allotted in most commonly used FACS setups to initialize and stabilize the fluid stream and perform droplet calibration. Seventh, control samples are typically run in sequence prior to the actual sample collection to set up compensation matrices, doublet rejection, setting gates, etc. Users either perform steps six and seven themselves ahead of time or require the assistance of a technician in parallel. Finally, post-FACS, there are often steps to ensure that only labeled single cells are present in each well; for example, by checking samples in a high-content screening setup such as a fast plate imager.
To circumvent the steps outlined above and facilitate a relatively quick, targeted sequencing of a small population of single fluorescently labeled neurons, we describe a manual sorting procedure followed by two rounds of a highly sensitive in vitro amplification protocol, called double in-vitro transcription with absolute counts sequencing (DIVA-Seq). The RNA amplification and cDNA library generation are adapted from Eberwine et al.6 and Hashimshony et al.7, with certain modifications to suit mouse interneurons that have smaller cellular volumes; furthermore, we have also found that it is equally useful for excitatory pyramidal neurons.

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			<td height="40" style="height:40px;width:261px;">Ampure Xp magnetic&#160; beads</td>
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			<td>Agilent</td>
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			<td>Agilent</td>
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			<td>Leica</td>
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			<td>Warner instruments</td>
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			<td>Sutter Instruments Co</td>
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			<td>Thermo Microm</td>
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single-cell rna sequencing of fluorescently labeled mouse neurons using manual sorting and double in vitro transcription with absolute counts sequencing (diva-seq)

Single-cell RNA sequencing (RNA-seq) is now a widely implemented tool for assaying gene expression. Commercially available single-cell RNA-sequencing platforms process all input cells indiscriminately. Sometimes, fluorescence-activated cell sorting (FACS) is used upstream to isolate a specifically labeled population of interest. A limitation of FACS is the need for high numbers of input cells with significantly labeled fractions, which is impractical for collecting and profiling rare or sparsely labeled neuron populations from the mouse brain. Here, we describe a method for manually collecting sparse fluorescently labeled single neurons from freshly dissociated mouse brain tissue. This process allows for capturing single-labeled neurons with high purity and subsequent integration with an in vitro transcription-based amplification protocol that preserves endogenous transcript ratios. We describe a double linear amplification method that uses unique molecule identifiers (UMIs) to generate individual mRNA counts. Two rounds of amplification results in a high degree of gene detection per single cell.

Using the protocol described above, GABAergic neurons were manually sorted (Figure 1) and RNA was amplified, then made into a cDNA library (Figure 2) and sequenced at high depth8. The amplified RNA (aRNA) products ranged between 200&#8211;4,000 bp in size, with a peak distribution slightly above 500 bp (Figure 3A). The bead-purified cDNA library was further size-restricted by ...

Watch this Scientific Journal Video about Single-cell RNA Sequencing of Fluorescently Labeled Mouse Neurons Using Manual Sorting and Double In Vitro Transcription with Absolute Counts Sequencing DIVA-

Single-cell RNA Sequencing of Fluorescently Labeled Mouse Neurons Using Manual Sorting and Double In Vitro Transcription with Absolute Counts Sequencing DIVA-Seq

This protocol describes the manual sorting procedure to isolate single fluorescently labeled neurons followed by in vitro transcription-based mRNA amplification for high-depth single-cell RNA sequencing.

Single-cell RNA Sequencing of Fluorescently Labeled Mouse Neurons Using Manual Sorting and Double In Vitro Transcription with Absolute Counts Sequencing (DIVA-Seq)

Single-cell RNA sequencing (RNA-seq) is now a widely implemented tool for assaying gene expression. Commercially available single-cell RNA-sequencing ...

This method can help solve a key obstacle in the field of single-neuron isolation and sequencing. Such as collecting specific population or a subpopulation of fluorescently labeled neuron from user-defined brain area. The main advantage of this technique is that it ensures the single neuron of interest is captured without contaminating debris.It is also relatively gentle, which is important for fragile neuron types that die quickly when subjected to the fluid pressures of conventional FACS sorting. Start by preparing pulled glass microcapillaries with 10 to 15 micron exit diameter using a capillary puller. Use fine scissors to cut the tip of the capillary to get the desired board diameter.Then use tubing connectors to attach a 120 to 150-centimeter length of flexible silicone tubing with 0.8 millimeter inside diameter to a 0.2 micron PVDF membrane syringe filter and a two-way tubing valve. Prepare 500 milliliters of chilled artificial cerebral spinal fluid or ACSF and oxygenate by bubbling 5%carbon dioxide balanced oxygen through an Airstone for 15 minutes or until the solution clears completely. Prepare three 150-milliliter beakers each containing 100 milliliters of ACSF.To one, add a cocktail of activity blockers. To another, add Streptococcus fraction for protease to a final concentration of one milligram per milliliter. To the final beaker, add FBS to a final concentration of 1%and oxygenate with 5%carbon dioxide-balanced oxygen through an Airstone.Finally, make three long-stemmed Pasteur pipettes with decreasing exit diameters by rolling them over an open flame. Dissect the brain from a euthanized mouse by opening the cranium with a small scissor and extracting the fresh brain using fine forceps without damaging the cortex. Place the brain in chilled and oxygenated ACSF leaving an Airstone attached to 5%carbon dioxide-balanced oxygen during the entire duration of the sectioning.Position the brain on the vibratome chuck and cut coronal or sagittal sections at 300 micron thickness. Collect as many sections as needed to obtain a minimum of 10 to 50 labeled cells. Put slices on a cotton-meshed slice holder placed inside a beaker so they are bathed in oxygenated ACSF.Move the slices into the beaker containing ACSF with activity blockers and block for 15 to 20 minutes at room temperature while bubbling oxygen using an Airstone. Move the slices to the beaker containing ACSF with the protease solution to perform mild digestion at room temperature. Following the digestion, wash out the protease by moving slices back to the beaker containing ACSF with activity blocker solution for five to 10 minutes at room temperature.Keep bubbling oxygen. Next, prepare a 100-millimeter Petri dish containing ACSF with 1%FBS at room temperature and move individual sections into the disk for microdissection. Under a fluorescent dissections scope, use a pair of fine forceps to micro dissect areas and layers of interest having a minimum of 10 to 50 cells.Using a Pasteur pipette, move the micro-dissected pieces to a 2-milliliter microcentrifuge tube containing approximately 0.8 milliliters of 1%FBS in ACSF solution. Titrate the dissected tissue in the micro-fuge tube at room temperature. Perform approximately 10 strokes with each of the flamed Pasteur pipettes starting with the biggest and ending with the smallest exit diameter.Dispense the dissociated cells into a 100-millimeter Petri dish containing oxygenated ACSF and wait five to seven minutes for the cells to gradually settle. Observe the GFP and RFP signal under a dissection microscope. Identify debris by examining the morphology under bright-field illumination.Once an area of cells with little debris has been identified, use the capillary and attach to tubing to pick cells by blocking the end of the tubing valve with the tongue. Then position the capillary close to the cells. Release the block on the capillary and quickly block again to capture the cell using capillary action.Move the capillary to a 100-millimeter Petri dish with fresh oxygenated ACSF and gently blow into the tube while observing the capillary tip under fluorescence optics to dispense the cells into the dish. Repeat the collection procedure until 100 to 150 cells are collected making sure that contaminants, such as debris, are minimal in bright-field differential interference contrast optics. Finally, using a fresh micro-capillary pipette each time, choose a single cell and expel it in no more than 0.5 microliters into a 0.2 microliter micro-fuge tube containing one microliter of sample-collection buffer with primers.Break the pipette tip in the micro-fuge tube to ensure that the cell stays in the collection buffer. Freeze the cells by putting the tubes on dry ice. Store in a minus 80-degree Celsius freezer until processing for RNA amplification.GABAergic neurons were isolated from the cingulet cortex of the mouse brain. RNA amplified from the manually sorted neurons ranged between 200 to 4, 000 base pairs in size with a peak distribution slightly above 500 base pairs. After bead purification, the cDNA library is further size restricted by a second round of purification using beads to eliminate fragments less than 200 base pairs and for the peak at approximately 350 base pairs.Sequencing showed a 4.8 times 10 to the 5th median or 6.9 times 10 to the 5th averaged mapped reads per cell. After duplicate RNA removal using UMIs, each single cell had a 1.0 times 10 to the 5th median or 1.4 times 10 to the 5th average unique reads per cell. In each single cell external RNA controls consortium, spike in RNA was used as an internal control to calculate absolute number of molecules added to the sample.There was a linear relationship of input to observed counts with a slope of 0.92 and adjusted R square of 0.94. An average of around 10, 000 genes per single neuron were detected using this procedure with more than 95%of the single cells detecting more than 6, 000 genes. After its development, this technique paved the way for molecular biologists to explore the transcriptome of distinct well-characterized mouse cortical interneurons, and identified select gene categories that are responsible for encoding the cellular identity.

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Research

JoVE Journal

Neuroscience

Non-Laser Capture Microscopy Approach for the Microdissection of Discrete Mouse Brain Regions for Total RNA Isolation and Downstream Next-Generation Sequencing and Gene Expression Profiling

As technological platforms, approaches such as next-generation sequencing, microarray, and qRT-PCR have great promise for expanding our understanding of the breadth of molecular regulation. Newer approaches such as high-resolution RNA sequencing (RNA-Seq)1 provides new and expansive information about tissue- or state-specific expression such as relative transcript levels, alternative splicing, and micro RNAs2-4. Prospects for employing the RNA-Seq method in comparative whole transcriptome profiling5 within discrete tissues or between phenotypically distinct groups of individuals affords new avenues for elucidating molecular mechanisms involved in both normal and abnormal physiological states. Recently, whole transcriptome profiling has been performed on human brain tissue, identifying gene expression differences associated with disease progression6. However, the use of next-generation sequencing has yet to be more widely integrated into mammalian studies.
Gene expression studies in mouse models have reported distinct profiles within various brain nuclei using laser capture microscopy (LCM) for sample excision7,8. While LCM affords sample collection with single-cell and discrete brain region precision, the relatively low total RNA yields from the LCM approach can be prohibitive to RNA-Seq and other profiling approaches in mouse brain tissues and may require sub-optimal sample amplification steps. Here, a protocol is presented for microdissection and total RNA extraction from discrete mouse brain regions. Set-diameter tissue corers are used to isolate 13 tissues from 750-&mu;m serial coronal sections of an individual mouse brain. Tissue micropunch samples are immediately frozen and archived. Total RNA is obtained from the samples using magnetic bead-enabled total RNA isolation technology. Resulting RNA samples have adequate yield and quality for use in downstream expression profiling. This microdissection strategy provides a viable option to existing sample collection strategies for obtaining total RNA from discrete brain regions, opening possibilities for new gene expression discoveries.

Non-Laser Capture Microscopy Approach for the Microdissection of Discrete Mouse Brain Regions for Total RNA Isolation and Downstream Next-Generation Sequencing and Gene Expression Profiling  |

RNA expression profiling of discrete mouse brain regions requires a precise and repeatable tissue collection strategy. A protocol that uses both coronal brain sectioning and tissue corer-assisted microdissection is described here. The yield and quality of total RNA obtained from the resulting samples confirms the utility of the outlined method.

As technological platforms, approaches such as next-generation sequencing, microarray, and qRT-PCR have great promise for expanding our understanding of ...

Profiling Voltage-gated Potassium Channel mRNA Expression in Nigral Neurons using Single-cell RT-PCR Techniques

In mammalian central nervous system, different types of neurons with diverse molecular and functional characteristics are intermingled with each other, difficult to separate and also not easily identified by their morphology. Thus, it is often difficult to analyze gene expression in a specific neuron type. Here we document a procedure that combines whole-cell patch clamp recording techniques with single-cell reverse transcription polymerase chain reaction (scRT-PCR) to profile mRNA expression in different types of neurons in the substantial nigra. Electrophysiological techniques are first used to record the neurophysiological and functional properties of individual neurons. Then, the cytoplasm of single electrophysiologically characterized nigral neurons is aspirated and subjected to scRT-PCR analysis to obtain mRNA expression profiles for neurotransmitter synthesis enzymes, receptors, and ion channels. The high selectivity and sensitivity make this method particularly useful when immunohistochemistry can not be used due to a lack of suitable antibody or low expression level of the protein. This method is also applicable to neurons in other brain areas.

Neurons are first characterized electrophysiologically. Then the cytoplasm from the recorded neuron is aspirated and subjected to reverse transcription-PCR analysis to detect the expression of mRNAs for neurotransmitter synthesis enzymes, ion channels, and receptors.

In mammalian central nervous system, different types of neurons with diverse molecular and functional characteristics are intermingled with each other, ...

Single-cell Profiling of Developing and Mature Retinal Neurons

Highly specialized, but exceedingly small populations of cells play important roles in many tissues. The identification of cell-type specific markers and gene expression programs for extremely rare cell subsets has been a challenge using standard whole-tissue approaches. Gene expression profiling of individual cells allows for unprecedented access to cell types that comprise only a small percentage of the total tissue1-7. In addition, this technique can be used to examine the gene expression programs that are transiently expressed in small numbers of cells during dynamic developmental transitions8.
This issue of cellular diversity arises repeatedly in the central nervous system (CNS) where neuronal connections can occur between quite diverse cells9. The exact number of distinct cell types is not precisely known, but it has been estimated that there may be as many as 1000 different types in the cortex itself10. The function(s) of complex neural circuits may rely on some of the rare neuronal types and the genes they express. By identifying new markers and helping to molecularly classify different neurons, the single-cell approach is particularly useful in the analysis of cell types in the nervous system. It may also help to elucidate mechanisms of neural development by identifying differentially expressed genes and gene pathways during early stages of neuronal progenitor development.
As a simple, easily accessed tissue with considerable neuronal diversity, the vertebrate retina is an excellent model system for studying the processes of cellular development, neuronal differentiation and neuronal diversification. However, as in other parts of the CNS, this cellular diversity can present a problem for determining the genetic pathways that drive retinal progenitors to adopt a specific cell fate, especially given that rod photoreceptors make up the majority of the total retinal cell population11. Here we report a method for the identification of the transcripts expressed in single retinal cells (Figure 1). The single-cell profiling technique allows for the assessment of the amount of heterogeneity present within different cellular populations of the retina2,4,5,12. In addition, this method has revealed a host of new candidate genes that may play role(s) in the cell fate decision-making processes that occur in subsets of retinal progenitor cells8. With some simple adjustments to the protocol, this technique can be utilized for many different tissues and cell types.

A method for the isolation of single retinal cells and subsequent amplification of their cDNAs is described. Single-cell transcriptomics reveals the degree of cellular heterogeneity present in a tissue and uncovers new marker genes for rare cell populations. The accompanying protocol can be adjusted to suit many different cell types.

Highly specialized, but exceedingly small populations of cells play important roles in many tissues. The identification of cell-type specific markers and ...

Real-time Imaging of Axonal Transport of Quantum Dot-labeled BDNF in Primary Neurons

BDNF plays an important role in several facets of neuronal survival, differentiation, and function. Structural and functional deficits in axons are increasingly viewed as an early feature of neurodegenerative diseases, including Alzheimer&#8217;s disease (AD) and Huntington&#8217;s disease (HD). As yet unclear is the mechanism(s) by which axonal injury is induced. We reported the development of a novel technique to produce biologically active, monobiotinylated BDNF (mBtBDNF) that can be used to trace axonal transport of BDNF. Quantum dot-labeled BDNF (QD-BDNF) was produced by conjugating quantum dot 655 to mBtBDNF. A microfluidic device was used to isolate axons from neuron cell bodies. Addition of QD-BDNF to the axonal compartment allowed live imaging of BDNF transport in axons. We demonstrated that QD-BDNF moved essentially exclusively retrogradely, with very few pauses, at a moving velocity of around 1.06 &#956;m/sec. This system can be used to investigate mechanisms of disrupted axonal function in AD or HD, as well as other degenerative disorders.

Axonal transport of BDNF, a neurotrophic factor, is critical for the survival and function of several neuronal populations. Some degenerative disorders are marked by disruption of axonal structure and function. We demonstrated the techniques used to examine live trafficking of QD-BDNF in microfluidic chambers using primary neurons.

BDNF plays an important role in several facets of neuronal survival, differentiation, and function. Structural and functional deficits in axons are ...

Reliable Identification of Living Dopaminergic Neurons in Midbrain Cultures Using RNA Sequencing and TH-promoter-driven eGFP Expression

In Parkinson&#39;s Disease (PD) there is widespread neuronal loss throughout the brain with pronounced degeneration of dopaminergic neurons in the SNc, leading to bradykinesia, rigidity, and tremor. The identification of living dopaminergic neurons in primary Ventral Mesencephalic (VM) cultures using a fluorescent marker provides an alternative way to study the selective vulnerability of these neurons without relying on the immunostaining of fixed cells. Here, we isolate, dissociate, and culture mouse VM neurons for 3 weeks. We then identify dopaminergic neurons in the cultures using eGFP fluorescence (driven by a Tyrosine Hydroxylase (TH) promoter). Individual neurons are harvested into microcentrifuge tubes using glass micropipettes. Next, we lyse the harvested cells, and conduct cDNA synthesis and transposon-mediated &#34;tagmentation&#34; to produce single cell RNA-Seq libraries1,2,3,4,5. After passing a quality-control check, single-cell libraries are sequenced and subsequent analysis is carried out to measure gene expression. We report transcriptome results for individual dopaminergic and GABAergic neurons isolated from midbrain cultures. We report that 100% of the live TH-eGFP cells that were harvested and sequenced were dopaminergic neurons. These techniques will have widespread applications in neuroscience and molecular biology.

In Parkinson&#39;s Disease (PD), Substantia Nigra (SNc) dopaminergic neurons degenerate, leading to motor dysfunction. Here we report a protocol for culturing ventral midbrain neurons from a mouse expressing eGFP driven by a Tyrosine Hydroxylase (TH) promoter sequence, harvesting individual fluorescent neurons from the cultures, and measuring their transcriptome using RNA-seq.

In Parkinson&#39;s Disease (PD) there is widespread neuronal loss throughout the brain with pronounced degeneration of dopaminergic neurons in the SNc, ...

Single-cell RNA-Seq of Defined Subsets of Retinal Ganglion Cells

The discovery of cell type-specific markers can provide insight into cellular function and the origins of cellular heterogeneity. With a recent push for the improved understanding of neuronal diversity, it is important to identify genes whose expression defines various subpopulations of cells. The retina serves as an excellent model for the study of central nervous system diversity, as it is composed of multiple major cell types. The study of each major class of cells has yielded genetic markers that facilitate the identification of these populations. However, multiple subtypes of cells exist within each of these major retinal cell classes, and few of these subtypes have known genetic markers, although many have been characterized by morphology or function. A knowledge of genetic markers for individual retinal subtypes would allow for the study and mapping of brain targets related to specific visual functions and may also lend insight into the gene networks that maintain cellular diversity. Current avenues used to identify the genetic markers of subtypes possess drawbacks, such as the classification of cell types following sequencing. This presents a challenge for data analysis and requires rigorous validation methods to ensure that clusters contain cells of the same function. We propose a technique for identifying the morphology and functionality of a cell prior to isolation and sequencing, which will allow for the easier identification of subtype-specific markers. This technique may be extended to non-neuronal cell types, as well as to rare populations of cells with minor variations. This protocol yields excellent-quality data, as many of the libraries have provided read depths greater than 20 million reads for single cells. This methodology overcomes many of the hurdles presented by Single-cell RNA-Seq and may be suitable for researchers aiming to profile cell types in a straightforward and highly efficient manner.

Here, we present a combinatorial approach for classifying neuronal cell types prior to isolation and for the subsequent characterization of single-cell transcriptomes. This protocol optimizes the preparation of samples for successful RNA Sequencing (RNA-Seq) and describes a methodology designed specifically for the enhanced understanding of cellular diversity.

The discovery of cell type-specific markers can provide insight into cellular function and the origins of cellular heterogeneity. With a recent push for ...

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains brain homeostasis. The principal sites of the barrier are endothelial cells of the brain capillaries whose barrier function results from tight intercellular junctions and efflux transporters expressed on the plasma membrane. This function is regulated by pericytes and astrocytes that together form the neurovascular unit (NVU). Several neurological diseases such as stroke, Alzheimer&#39;s disease (AD), brain tumors are associated with an impaired BBB function. Assessment of the BBB permeability is therefore crucial in evaluating the severity of the neurological disease and the success of the treatment strategies employed.
We present here a simple yet robust permeability assay that have been successfully applied to several mouse models both, genetic and experimental. The method is highly quantitative and objective in comparison to the tracer fluorescence analysis by microscopy that is commonly applied. In this method, mice are injected intraperitoneally with a mix of aqueous inert fluorescent tracers followed by anesthetizing the mice. Cardiac perfusion of the animals is performed prior to harvesting brain, kidneys or other organs. Organs are homogenized and centrifuged followed by fluorescence measurement from the supernatant. Blood drawn from the cardiac puncture just before perfusion serves for normalization purpose to the vascular compartment. The tissue fluorescence is normalized to the wet weight and serum fluorescence to obtain a quantitative tracer permeability index. For additional confirmation, the contralateral hemi-brain preserved for immunohistochemistry can be utilized for tracer fluorescence visualization purposes.

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Here we present a mouse brain vascular permeability assay using intraperitoneal injection of fluorescent tracers followed by perfusion that is applicable to animal models of blood-brain barrier dysfunction. One hemi-brain is used for assessing permeability quantitatively and the other for tracer visualization/immunostaining. The procedure takes 5 - 6 h for 10 mice.

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains ...

Identifying Transcription Factor Olig2 Genomic Binding Sites in Acutely Purified PDGFR&#945;+ Cells by Low-cell Chromatin Immunoprecipitation Sequencing Analysis

In mammalian cells, gene transcription is regulated in a cell type specific manner by the interactions of transcriptional factors with genomic DNA. Lineage-specific transcription factors are considered to play essential roles in cell specification and differentiation during development. ChIP coupled with high-throughput DNA sequencing (ChIP-seq) is widely used to analyze genome-wide binding sites of transcription factors (or its associated complex) to genomic DNA. However, a large number of cells are required for one standard ChIP reaction, which makes it difficult to study the limited number of isolated primary cells or rare cell populations. In order to understand the regulatory mechanism of oligodendrocyte lineage-specific transcription factor Olig2 in acutely purified mouse OPCs, a detailed method using ChIP-seq to identify the genome-wide binding sites of Olig2 (or Olig2 complex) is shown. First, the protocol explains how to purify the platelet-derived growth factor receptor alpha (PDGFR&#945;) positive OPCs from mouse brains. Next, Olig2 antibody mediated ChIP and library construction are performed. The last part describes the bioinformatic software and procedures used for Olig2 ChIP-seq analysis. In summary, this paper reports a method to analyze the genome-wide bindings of transcriptional factor Olig2 in acutely purified brain OPCs.

Identifying Transcription Factor Olig2 Genomic Binding Sites in Acutely Purified PDGFR&amp;#945;+ Cells by Low-cell Chromatin Immunoprecipitation Sequencing Analysis

Here we present a protocol which is designed to analyze the genome-wide binding of the oligodendrocyte transcription factor 2 (Olig2) in acutely purified brain oligodendrocyte precursor cells (OPCs) by performing low-cell chromatin immunoprecipitation (ChIP), library preparation, high-throughput sequencing and bioinformatic data analysis.

In mammalian cells, gene transcription is regulated in a cell type specific manner by the interactions of transcriptional factors with genomic DNA. ...

Single Cell Multiplex Reverse Transcription Polymerase Chain Reaction After Patch-clamp

The cerebral cortex is composed of numerous cell types exhibiting various morphological, physiological, and molecular features. This diversity hampers easy identification and characterization of these cell types, prerequisites to study their specific functions. This article describes the multiplex single cell reverse transcription polymerase chain reaction (RT-PCR) protocol, which allows, after patch-clamp recording in slices, to detect simultaneously the expression of tens of genes in a single cell. This simple method can be implemented with morphological characterization and is widely applicable to determine the phenotypic traits of various cell types and their particular cellular environment, such as in the vicinity of blood vessels. The principle of this protocol is to record a cell with the patch-clamp technique, to harvest and reverse transcribe its cytoplasmic content, and to detect qualitatively the expression of a predefined set of genes by multiplex PCR. It requires a careful design of PCR primers and intracellular patch-clamp solution compatible with RT-PCR. To ensure a selective and reliable transcript detection, this technique also requires appropriate controls from cytoplasm harvesting to amplification steps. Although precautions discussed here must be strictly followed, virtually any electrophysiological laboratory can use the multiplex single cell RT-PCR technique.

This protocol describes the critical steps and precautions required to perform single cell multiplex reverse transcription polymerase chain reaction after patch-clamp. This technique is a simple and effective method to analyze the expression profile of a predetermined set of genes from a single cell characterized by patch-clamp recordings.

The cerebral cortex is composed of numerous cell types exhibiting various morphological, physiological, and molecular features. This diversity hampers ...

Isolation of Adult Spinal Cord Nuclei for Massively Parallel Single-nucleus RNA Sequencing

Probing an individual cell&#39;s gene expression enables the identification of cell type and cell state. Single-cell RNA sequencing has emerged as a powerful tool for studying transcriptional profiles of cells, particularly in heterogeneous tissues such as the central nervous system. However, dissociation methods required for single cell sequencing can lead to experimental changes in the gene expression and cell death. Furthermore, these methods are generally restricted to fresh tissue, thus limiting studies on archival and bio-bank material. Single nucleus RNA sequencing (snRNA-Seq) is an appealing alternative for transcriptional studies, given that it accurately identifies cell types, permits the study of tissue that is frozen or difficult to dissociate, and reduces dissociation-induced transcription. Here, we present a high-throughput protocol for rapid isolation of nuclei for downstream snRNA-Seq. This method enables isolation of nuclei from fresh or frozen spinal cord samples and can be combined with two massively parallel droplet encapsulation platforms.

Here, we present a protocol to rapidly isolate high-quality nuclei from the fresh or frozen tissue for downstream massively parallel RNA sequencing. We include detergent-mechanical and hypotonic-mechanical tissue disruption and cell lysis options, both of which can be used for isolation of nuclei.

Probing an individual cell&#39;s gene expression enables the identification of cell type and cell state. Single-cell RNA sequencing has emerged as a ...