We appreciate Laura Sieber, Anna Neuerburg, Yassin Harim, and Petra Schroeter for technical assistance. We also thank Drs. K. Reifenberg, K. Dell and P. Pr&#252;ckl&#160;for helpful assistance for animal experiments at DKFZ; the Imaging Core Facilities of the DKFZ and the Carl Zeiss Imaging Center in the DKFZ for confocal microscopy imaging. This work was supported by the Deutsche Forschungsgemeinschaft, KA 4472/1-1 (to D.K.).

All animal experiments were conducted according to animal welfare regulations and have been approved by the responsible authorities (Regierungspr&#228;sidium Karlsruhe, approval numbers: G90/13, G176/13, G32/14, G48/14, and G133/14).
1. Generate pU6-sgRNA-Cbh-Cre Plasmids
<ol>
	<li>Design the sgRNA to target a gene-of-interest according to the previously published protocol14. 
	NOTE: In this experiment, two sgRNAs are designed to target the mouse Top2b g...

<ol>
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J., Liu, L., Shih, D. J. H., Finkelstein, D., Murphy, B. 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=Novel+MYC-driven+medulloblastoma+models+from+multiple+embryonic+cerebellar+cells.">Novel MYC-driven medulloblastoma models from multiple embryonic cerebellar cells.</a> Oncogene. , (2017).</li><li>Feng, W., Kawauchi, D., Korkel-Qu, H., Deng, H., Serger, E., Sieber, 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=Chd7+is+indispensable+for+mammalian+brain+development+through+activation+of+a+neuronal+differentiation+programme.">Chd7 is indispensable for mammalian brain development through activation of a neuronal differentiation programme.</a> Nat Commun. 8, 14758 (2017).</li><li>Platt, R. J., Chen, S., Zhou, Y., Yim, M. J., Swiech, L., Kempton, H. 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A., Cox, D., Lin, S., Barretto, R., Habib, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiplex+genome+engineering+using+CRISPR/Cas+systems.">Multiplex genome engineering using CRISPR/Cas systems.</a> Science. 339 (6121), 819-823 (2013).</li><li>Mashiko, D., Fujihara, Y., Satouh, Y., Miyata, H., Isotani, A., Ikawa, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+mutant+mice+by+pronuclear+injection+of+circular+plasmid+expressing+Cas9+and+single+guided+RNA.">Generation of mutant mice by pronuclear injection of circular plasmid expressing Cas9 and single guided RNA.</a> Scientific Reports. 3, 3355 (2013).</li><li>Gibson, D. G., Smith, H. O., Hutchison, C. A., Venter, J. C., Merryman, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+synthesis+of+the+mouse+mitochondrial+genome.">Chemical synthesis of the mouse mitochondrial genome.</a> Nature. 7 (11), 901-903 (2010).</li><li>Baumgart, J., Baumgart, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortex-,+Hippocampus-,+Thalamus-,+Hypothalamus-,+Lateral+Septal+Nucleus-+and+Striatum-specific+In+Utero+Electroporation+in+the+C57BL/6+Mouse.">Cortex-, Hippocampus-, Thalamus-, Hypothalamus-, Lateral Septal Nucleus- and Striatum-specific In Utero Electroporation in the C57BL/6 Mouse.</a> J Vis Exp. (107), e53303 (2016).</li><li>Martinez, S., Andreu, A., Mecklenburg, N., Echevarria, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+and+molecular+basis+of+cerebellar+development.">Cellular and molecular basis of cerebellar development.</a> Frontiers in Neuroanatomy. 7, 18 (2013).</li></ol>

Using exo utero electroporation, we have previously reported siRNA-based in vivo functional analyses of Atoh1 at an early stage of cerebellar granule cell differentiation8. Due to siRNA dilution/degradation and exposure of embryos outside the uterine wall, phenotypic analysis of the electroporated granule cells was limited to embryonic stages. However, the current method enabled analysis of the phenotype of postnatal animals.
Our previous study demonst...

Brain diseases are one of the most dreadful mortal diseases. They often result from genetic mutations and subsequent dysregulation. To understand molecular mechanisms of brain diseases, ever-lasting efforts to decipher the genomes of human patients have discovered a number of potential causative genes. So far, germline genetically engineered animal models have been utilized for in vivo gain-of-function (GOF) and loss-of-function (LOF) analyses of such candidate genes. Due to the accelerated development of functional validation studies, a more feasible and flexible in vivo gene assay system for studying gene function is desirable.
The application of an in vivo electroporation-based gene transfer system to the developing mouse brain is suitable for this purpose. In fact, several studies using in utero electroporation have shown their potential to conduct functional analyses in the developing brain1,2,3. Actually, several regions of the mouse brain, such as the cerebral cortex4, retina5, diencephalon6, hindbrain7, cerebellum8, and spinal cord9 have been targeted by somatic gene delivery approaches, so far.
Indeed, transient gene expression by in vivo electroporation on embryonic mouse brains has long been used for GOF analysis. Recent transposon-based genomic integration technologies further enabled long-term and/or conditional expression of genes of interest10,11, which is advantageous to dissect gene function in a spatial and temporal manner during development. In contrast to GOF analysis, LOF analysis has been more challenging. While transient transfection of siRNAs and shRNA-carrying plasmids was performed, long-term effects of LOF of genes are not guaranteed due to eventual degradation of exogenously introduced nucleic acids, such as plasmids and dsRNAs. However, the CRISPR/Cas technology provides a break-through in LOF analyses. Genes encoding fluorescent proteins (e.g., GFP) or bioluminescent proteins (e.g., firefly luciferase) have been co-transfected with CRISPR-Cas9 and sgRNAs to label the cells exposed to CRISPR-Cas9-mediated somatic mutations. Nevertheless, this approach might have limitations in functional studies on proliferating cells, since exogenous marker genes are diluted and degraded after long-term proliferation. While the transfected cells and their daughter cells undergo CRISPR-induced mutations in their genomes, their footprints might get lost over time. Thus, genetic labeling approaches would be suitable to overcome this issue.
We recently developed a CRISPR-based LOF method in cerebellar granule cells that undergo long-term proliferation during their differentiation12. To genetically label the transfected cells, we constructed a plasmid carrying a sgRNA together with Cre and introduced the plasmid into the cerebella of Rosa26-CAG-LSL-Cas9-P2A-EGFP mice13 using in utero electroporation. Unlike regular plasmid vectors encoding EGFP, this approach successfully labeled transfected granule neuron precursors (GNPs) and their daughter cells. This method provides great support in understanding in vivo function of genes of interest in proliferating cells in normal brain development and a tumor-prone background.

<table>
	<tbody>
		<tr>
			<td>Alexa 488 Goat anti-Chicken</td>
			<td>ThermoFisher</td>
			<td>A11039</td>
			<td>1:400 dilution</td>
		</tr>
		<tr>
			<td>Alexa 568 Donkey anti-Mouse</td>
			<td>Life Technologies</td>
			<td>A-10037</td>
			<td>1:400 dilution</td>
		</tr>
		<tr>
			<td>Alexa 594 Donkey anti-Rabbit</td>
			<td>ThermoFisher</td>
			<td>A21207</td>
			<td>1:400 dilution</td>
		</tr>
		<tr>
			<td>Alexa 647 Donkey anti-Rabbit</td>
			<td>Life Technologies</td>
			<td>A31573</td>
			<td>1:400 dilution</td>
		</tr>
		<tr>
			<td>Alkaline Phosphatase (FastAP)</td>
			<td>ThermoFisher</td>
			<td>EF0654</td>
			<td></td>
		</tr>
		<tr>
			<td>Autoclave band</td>
			<td>Kisker Biotech</td>
			<td>150262</td>
			<td></td>
		</tr>
		<tr>
			<td>BamHI (HF)</td>
			<td>NEB</td>
			<td>R3136S</td>
			<td></td>
		</tr>
		<tr>
			<td>BbsI (FastDigest)</td>
			<td>ThermoFisher</td>
			<td>FD1014</td>
			<td></td>
		</tr>
		<tr>
			<td>Cellulose Filter Paper (Whatman)</td>
			<td>Sigma-Aldrich</td>
			<td>WHA10347525</td>
			<td></td>
		</tr>
		<tr>
			<td>Cloth</td>
			<td>Tork</td>
			<td>530378</td>
			<td></td>
		</tr>
		<tr>
			<td>Confocal laser scanning microscope</td>
			<td>Zeiss</td>
			<td>LSM800</td>
			<td></td>
		</tr>
		<tr>
			<td>D-Luciferin</td>
			<td>biovision</td>
			<td>7903-1</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Sigma-Aldrich</td>
			<td>D9542</td>
			<td>1:1000 dilution</td>
		</tr>
		<tr>
			<td>Disposable plastic molds (Tissue-Tek Cyromold)</td>
			<td>VWR</td>
			<td>4566</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM Glutamax</td>
			<td>ThermoFisher</td>
			<td>31966047</td>
			<td></td>
		</tr>
		<tr>
			<td>Donkey serum</td>
			<td>Sigma-Aldrich</td>
			<td>D9663</td>
			<td></td>
		</tr>
		<tr>
			<td>EcoRI (HF)</td>
			<td>NEB</td>
			<td>R3101S</td>
			<td></td>
		</tr>
		<tr>
			<td>Electro Square Porator</td>
			<td>BTX</td>
			<td>ECM830</td>
			<td></td>
		</tr>
		<tr>
			<td>Endofree Maxi Kit</td>
			<td>Qiagen</td>
			<td>12362</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Merck</td>
			<td>107017</td>
			<td></td>
		</tr>
		<tr>
			<td>Eye ointment (Bepanthen)</td>
			<td>Bayer</td>
			<td>81552983</td>
			<td></td>
		</tr>
		<tr>
			<td>Fast Green</td>
			<td>Merck</td>
			<td>104022</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>ThermoFisher</td>
			<td>10270-016</td>
			<td></td>
		</tr>
		<tr>
			<td>Filter (0.22 &#181;m)</td>
			<td>Merck</td>
			<td>F8148</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescent cell imager (ZOE)</td>
			<td>Biorad</td>
			<td>1450031</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps straight</td>
			<td>Fine Science Tools</td>
			<td>91150-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Gauze (X100 ES-pads 8f 10 x 10 cm)</td>
			<td>Fisher Scientific</td>
			<td>15387311</td>
			<td></td>
		</tr>
		<tr>
			<td>GFP antibody</td>
			<td>Abcam</td>
			<td>ab13970</td>
			<td>1:1000 dilution</td>
		</tr>
		<tr>
			<td>Gibson Assembly Master Mix</td>
			<td>NEB</td>
			<td>E2611S</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Capillary with Filament</td>
			<td>Narishige</td>
			<td>GD1-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Heating Pad</td>
			<td>ThermoLux</td>
			<td>463265 / -67</td>
			<td></td>
		</tr>
		<tr>
			<td>Image Processing software (ImageJ and Fiji)</td>
			<td>NIH</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin syringe (B. Braun OMNICAN U-100)</td>
			<td>Carl Roth</td>
			<td>AKP0.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Zoetis</td>
			<td>TU061219</td>
			<td></td>
		</tr>
		<tr>
			<td>IVIS Lumina LT Series III Caliper</td>
			<td>Perkin Elmer</td>
			<td>CLS136331</td>
			<td></td>
		</tr>
		<tr>
			<td>Kalt Suture Needles</td>
			<td>Fine Science Tools</td>
			<td>12050-02</td>
			<td></td>
		</tr>
		<tr>
			<td>KAPA HIFI HOTSTART READY mix</td>
			<td>Kapa Biosystems</td>
			<td>KK2601</td>
			<td></td>
		</tr>
		<tr>
			<td>Ki67 antibody</td>
			<td>Abcam</td>
			<td>ab15580</td>
			<td>1:500 dilution</td>
		</tr>
		<tr>
			<td>Light Pointer</td>
			<td>Photonic</td>
			<td>PL3000</td>
			<td></td>
		</tr>
		<tr>
			<td>Liquid blocker pen</td>
			<td>Kisker Biotech</td>
			<td>MKP-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Metamizol</td>
			<td>WDT</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Microgrinder</td>
			<td>Narishige</td>
			<td>EG-45</td>
			<td></td>
		</tr>
		<tr>
			<td>Microinjector</td>
			<td>Narishige</td>
			<td>IM300</td>
			<td></td>
		</tr>
		<tr>
			<td>Micropipette Puller</td>
			<td>Sutter Instrument Co.</td>
			<td>P-97</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope software ZEN</td>
			<td>Zeiss</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Non-sterile Silk Suture Thread (0.12 mm)</td>
			<td>Fine Science Tools</td>
			<td>18020-50</td>
			<td></td>
		</tr>
		<tr>
			<td>O.C.T. Compound (Tissue-Tek)</td>
			<td>VWR</td>
			<td>4583</td>
			<td></td>
		</tr>
		<tr>
			<td>p27 antibody</td>
			<td>BD bioscience</td>
			<td>610241</td>
			<td>1:200 dilution</td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Roth</td>
			<td>335.3</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS (1x)</td>
			<td>Life Technologies</td>
			<td>14190169</td>
			<td></td>
		</tr>
		<tr>
			<td>pCAG-EGxxFP</td>
			<td>Addgene</td>
			<td>50716</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylenimine</td>
			<td>Sigma-Aldrich</td>
			<td>408727</td>
			<td></td>
		</tr>
		<tr>
			<td>pX330 plasmid</td>
			<td>Addgene</td>
			<td>42230</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAprep Spin Miniprep Kit</td>
			<td>Qiagen</td>
			<td>27104</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAquick Gel Extraction Kit</td>
			<td>Qiagen</td>
			<td>28704</td>
			<td></td>
		</tr>
		<tr>
			<td>Quick Ligation Kit</td>
			<td>NEB</td>
			<td>M2200S</td>
			<td></td>
		</tr>
		<tr>
			<td>Ring Forceps</td>
			<td>Fine Science Tools</td>
			<td>11103-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Slides (SuperFrost)</td>
			<td>ThermoFisher</td>
			<td>10417002</td>
			<td></td>
		</tr>
		<tr>
			<td>Software for biostatistics (Prism 7)</td>
			<td>GraphPad Software, Inc</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Spitacid</td>
			<td>EcoLab</td>
			<td>3003840</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Nikon</td>
			<td>C-PS</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma-Aldrich</td>
			<td>S5016</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical scissors</td>
			<td>Fine Science Tools</td>
			<td>91460-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical scissors with blunt tip</td>
			<td>Fine Science Tools</td>
			<td>14072-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Suture (Supramid schwarz DS 16, 1.5 (4/0))</td>
			<td>SMI</td>
			<td>220340</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA Ligation Buffer</td>
			<td>NEB</td>
			<td>B0202S</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 PNK</td>
			<td>NEB</td>
			<td>M0201S</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue scissors Blunt (11.5 cm)</td>
			<td>Fine Science Tools</td>
			<td>14072-10</td>
			<td></td>
		</tr>
		<tr>
			<td>TOP2B antibody</td>
			<td>Santa Cruz</td>
			<td>sc13059</td>
			<td>1:200 dilution</td>
		</tr>
		<tr>
			<td>Trypsin (2.5 %)</td>
			<td>ThermoFisher</td>
			<td>15090046</td>
			<td></td>
		</tr>
		<tr>
			<td>Tweezers w/5mm &#216; disk electrodes Platinum</td>
			<td>Xceltis GmbH</td>
			<td>CUY650P5</td>
			<td></td>
		</tr>
		<tr>
			<td>Vaporizer</td>
			<td>Dr&#228;gerwerk AG</td>
			<td>GS186</td>
			<td></td>
		</tr>
	</tbody>
</table>

crispr-mediated loss of function analysis in cerebellar granule cells using in utero electroporation-based gene transfer

Brain malformation is often caused by genetic mutations. Deciphering the mutations in patient-derived tissues has identified potential causative factors of the diseases. To validate the contribution of a dysfunction of the mutated genes to disease development, the generation of animal models carrying the mutations is one obvious approach. While germline genetically engineered mouse models (GEMMs) are popular biological tools and exhibit reproducible results, it is restricted by time and costs. Meanwhile, non-germline GEMMs often enable exploring gene function in a more feasible manner. Since some brain diseases (e.g., brain tumors) appear to result from somatic but not germline mutations, non-germline chimeric mouse models, in which normal and abnormal cells coexist, could be helpful for disease-relevant analysis. In this study, we report a method for the induction of CRISPR-mediated somatic mutations in the cerebellum. Specifically, we utilized conditional knock-in mice, in which Cas9 and GFP are chronically activated by the CAG (CMV enhancer/chicken &#223;-actin) promoter after Cre-mediated recombination of the genome. The self-designed single-guide RNAs (sgRNAs) and the Cre recombinase sequence, both encoded in a single plasmid construct, were delivered into cerebellar stem/progenitor cells at an embryonic stage using in utero electroporation. Consequently, transfected cells and their daughter cells were labeled with green fluorescent protein (GFP), thus facilitating further phenotypic analyses. Hence, this method is not only showing electroporation-based gene delivery into embryonic cerebellar cells but also proposing a novel quantitative approach to assess CRISPR-mediated loss-of-function phenotypes.

For in vivo functional analysis, it is critical to identify the cells into which exogenous gene(s) have been introduced. While the expression of a marker, such as GFP in non-proliferating cells can be followed-up for a long period of time, the signal gets sequentially lost in proliferating cells. An illustration of this effect is demonstrated in Figure 1. To circumvent losing the footprint of transfected cells in LOF analyses, we developed a novel ap...

Watch this Scientific Journal Video about CRISPR-mediated Loss of Function Analysis in Cerebellar Granule Cells Using In Utero Electroporation-based Gene Transfer at JoVE.com

CRISPR-mediated Loss of Function Analysis in Cerebellar Granule Cells Using In Utero Electroporation-based Gene Transfer

Conventional loss-of-function studies of genes using knockout animals have often been costly and time-consuming. Electroporation-based CRISPR-mediated somatic mutagenesis is a powerful tool to understand gene functions in vivo. Here, we report a method to analyze knockout phenotypes in proliferating cells of the cerebellum.

CRISPR-mediated Loss of Function Analysis in Cerebellar Granule Cells Using In Utero Electroporation-based Gene Transfer

Brain malformation is often caused by genetic mutations. Deciphering the mutations in patient-derived tissues has identified potential causative factors ...

The overall goal of this electroporation-based in vivo gene transfer approach is to evaluate the roles of genes of interest in differentiation of cerebellar granule cells using CRISPR-mediated loss of function analyses. This method can help answer key questions in the developmental neurosciences and the neuro-oncologies, such as for identification of the molecules important for normal cerebellar development and brain tumor formations. The procedure of in-utero electroporation will be demonstrated by Dr.Lena Herbst a post-doc from Professor Peter Lichter's laboratory, and then the following immunohistochemistry will be performed by Dr.Weijun Feng, a post-doc from Dr.Haikun Di's laboratory.The main advantage of this method is to endeavor as to feasibly knock out genes of interest in the cerebellar cells, using the CRISPR-cas9 technologies, instead of the generation of the combination of knock-out animals. Although this method can give insight into gene functions during normal cerebellar development, it can also be applied to other systems, such as the development of other physical brain regions and brain tumor modeling. Begin by loading a borosilicate glass capillary into a micropipette puller and pulling to create a fine tip.Label the capillary tip with black ink for better visualization during the injection, and draw a scaling on the glass. Working under a stereomicroscope, use a ruler and sharp needle tweezers to trim the tip to a length of about six millimeters and create a sharp, one-sided beveled edge. Filter a 1%fast green stock solution through a zero-point, 22 micron filter to remove dye particles from the solution.Mix the single-guide RNA plasmids in equal parts with the luciferase reporter plasmid to a final concentration of at least one microgram per milliliter for each plasmid. Color the plasmid solution with fast green at a final concentration of 0.5%After anesthetizing a pregnant CD-1 mouse with isoflurane, place the mouse on its back on a heating pad, and administer analgesic. Apply eye ointment to prevent eye dryness during surgery.Fix the lens with tape and sterilize the abdomen with a disinfectant. Cover the mouse with gauze, leaving only the surgical area exposed. After making a skin incision of about two centimeters in length, locate the linea alba and use blunt-tip tissue scissors to make a slightly smaller second incision through the peritoneum.Moisten the opened abdominal cavity with pre-warmed sterile PBS. Next, use ring forceps to carefully extract the uterine horns from the abdominal cavity. Grasp the uterine wall at the gap between the yolk sacs of two neighboring embryos and pull gently.Avoid any pressure on the embryo while pulling it through the incision. Once the uterine horns have been extracted, aspirate approximately 10 to 15 microliters of colored plasmid solution with the prepared glass capillary. Avoid any air bubbles during this process.Gently hold the embryo with ring forceps and locate the neck area. Slowly penetrate the dorsal hindbrain with the tip of the glass capillary and move into the fourth ventricle. Inject about one microliter of the plasmid mix.Confirm that the dyed DNA has not leaked from the brain, and is visible as a diamond-shaped structure. Here it is most important to fill the entire region of the fourth ventricle with plasmid solution, to deliver DNA also to the distal part of the cerebellar primordium. At the same time, make sure not to cause any bleeding during that process.Place platinum tweezers, equipped with five millimeter diameter electrode plates laterally over the head of the embryo, with the negative pole covering the ear, and the positive pole positioned at the cerebellar primordium over the uterine wall, and apply electric square pulses. When all embryos have been electroporated, carefully place the uterine horns back into the abdominal cavity, and fill with sterile PBS. Let the uterine horns slide into a natural position.Turn off anesthesia and place the animal belly-down into a new cage to recover. Before cryosectioning, fix the cerebella overnight in five milliliters of 4%PFA in PBS per brain, at four degrees Celsius. The next day, transfer the fixed cerebella to ten milliliters of 30%sucrose in PBS per brain, and incubate overnight at four degrees Celsius.The following day, after the tissue has sunk to the bottom of the tube, remove the brains from the sucrose, and soak up the remaining sucrose solution with a piece of cellulose filter paper. Next, immerse each cerebellum in optimal cutting temperature compound in a disposable plastic mold, and freeze on dry ice. Cut the cryogenic block into 10 micron thick sections, using a cryostat, and keep the sections at minus 80 degrees Celsius until use.When ready to proceed to immunostaining, first dry the slides at room temperature for 30 minutes, and then wash twice for 10 minutes each time in PBS. Circle the sections with a liquid blocker pen and incubate the sections in blocking solution for one hour at room temperature. Add primary antibodies against the molecules of interest in the blocking solution, and incubate overnight at four degrees Celsius.Wash the slides with 0.1%Triton containing PBS three times for 10 minutes each. Then add fluorophore conjugated secondary antibody diluted in blocking solution containing DAPI, and incubate the sections for one hour at room temperature in the dark. Wash the slides in PBS-T three times for 10 minutes each time, then mount the slides, and keep at four degrees Celsius until imaging.hek293T cells stably expressing streptococcus pyogenes cas9 were transfected with sgRNA expressing and targeting plasmids. GFP expression in live cells was monitored using a fluorescent cell imager 48 hours after transfection. This image shows an affected sgRNA sequence based on GFP expression.This image shows lack of GFP expression resulting from a non-effective sgRNA sequence. These images show immunostaining of GFP, Ki67, and p27 in cerebella from a p7-rosa26-LSL-cas9 knock-in mouse with floxed stop cassette and downstream bicistronic cas9 and EGFP sequences, that was subject to electroporation at E13.5 with a Cre plasmid expressing control sgRNA. The section is counter-stained with DAPI.Note GFP-expressing cells in the outer granule cell layer marked by Ki67. Once mastered, this surgery can be done in less than 30 minutes per mouse. While attempting this procedure, it is important to remember to handle the embryo very carefully, to always use sharp-tipped capillaries, and to position the electrodes in the precise angle to ensure delivery of the electric pulses to the roof of the fourth ventricle.After its development, this technique paved the way for researchers in the field of medical sciences to explore the causal factors of the neurological disorders, including the brain tumors in the mouse cerebellum.

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Research

JoVE Journal

Developmental Biology

9.3K visualizações.  German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance. The overall goal of this electroporation-based in vivo gene transfer approach is to evaluate the roles of genes of interest in differentiation of cerebellar granule cells using CRISPR-mediated loss of function analyses. This method can help answer key questions in the developmental neurosciences and the neuro-oncologies, such as for identification of the molecules important for normal cerebellar development and brain tumor formations. The procedure of in-utero electroporation will be demonstr...