The authors acknowledge the technical assistance of the INGM Imaging Facility (Istituto Nazionale di Genetica Molecolare &#34;Romeo ed Enrica Invernizzi&#34; (INGM), Milan, Italy), in particular C. Cordiglieri, for assistance during 3D multicolor DNA FISH images acquisition. This work has been supported by the following grants to B.B.: EPIGEN Italian flagship program, Association Fran&#231;aise contre les Myopathies (AFM-Telethon, grant nr 18754) and Giovani Ricercatori, Italian Ministry of Health (GR-2011-02349383). This work has been supported by the following grant to F.M.: Fondazione Cariplo (Bando Giovani, grant nr 2018-0321).

1. DNA probe preparation and labelling procedures with nick translation
<ol>
	<li>Purify and clean bacterial artificial chromosomes (BACs), plasmids or PCR products with specific kits (Table of Materials), resuspend in ddH2O, check by electrophoresis on an agarose gel and quantify.</li>
	<li>Perform nick translation on 1.5&#8722;2 &#181;g of DNA from step 1.1 in a final volume of 50 &#181;L by mixing all the reagents in a 0.5 mL low binding DNA tube according to Table 1. 
	NOTE: Directly labelled probes can improve the signal to noise ratio. Kits to produce indirectly and directly labelled probes with various Alexa fluorochromes by nick translation are commercially available.</li>
	<li>Incubate the nick translation mix in a thermal mixer at 16 &#176;C for a time depending on the length of the starting DNA material: 45 min for PCR products (a pool of PCR products of 2,000 bp each) and up to 4 h for BAC DNA and plasmids.</li>
	<li>Check the size of the probes produced in step 1.3 by electrophoresis on a 2.2% agarose gel. 
	NOTE: The optimal probe size is &#60;200 bp (Figure 1A).
	<ol>
		<li>If the DNA is not digested enough, add 5 U of DNA polymerase I and 0.05 U of DNase I to the reaction and incubate for 1&#8722;2 h at 16 &#176;C and subsequently re-check. Stop the reaction with 0.5 mM EDTA (final concentration). Store probes at -20 &#176;C.</li>
	</ol>
	</li>
	<li>For each DNA FISH experiment, precipitate the following quantities of probes depending on the starting DNA material from which the probes are produced: 200 ng from nick translated PCR products, 100 ng from nick translated BACs, or 300 ng from nick translated plasmid. Add ddH2O up to 150 &#181;L, 20 &#181;g of unlabelled salmon sperm DNA, 3.5 &#181;g of species-specific Cot-1 DNA, 3 volumes of 100% EtOH, and 1/10 volume of 3 M sodium acetate pH 5.2. Precipitate at -80 &#176;C for 1 h.</li>
	<li>Centrifuge at maximum speed for 1 h at 4 &#176;C and discard the supernatant. Wash the pellet twice with 70% EtOH.</li>
	<li>Resuspend the pellet in 2 &#181;L of 100% formamide pH 7.0, shake at 40 &#176;C for 30 min (can take up to a few hours) and then add an equal volume of 4x saline-sodium citrate (SSC)/20% dextran sulfate.
	<ol>
		<li>Prepare 20x SSC by mixing 175.3 g of NaCl and 88.2 g of sodium citrate in a final volume of 1 L of H2O. Autoclave, filter and prepare aliquots. 
		NOTE: For multicolor DNA FISH, the different probes can be precipitated together except for probes that can anneal with one another. In these specific cases, treat them separately, precipitate and resuspend the probes dividing the reagents mentioned in steps 1.5&#8722;1.7 with respect to the number of probes. Pool the probes only after resuspension in formamide. If glass coverslips greater than 10 mm or less than 10 mm are used, scale up/down the volume of the reagents used in steps 1.5&#8722;1.7 proportionally to the slide size. Hybridization probes can be stored at -20 &#176;C for a long period of time (up to two months).</li>
	</ol>
	</li>
</ol>
2. Cell fixation, pre-treatment and permeabilization
NOTE: Permeabilization and deproteinization passages are crucial steps. The time of reaction and concentration of the reagents strongly depend on the cell type, the cytoplasm abundance, and the nuclear morphology.
<ol>
	<li>Cell fixation, pre-treatment and permeabilization for human primary T lymphocytes 
	NOTE: This protocol is suitable for small cells, with small nuclei and a low amount of cytoplasm.
	<ol>
		<li>Use glass coverslips (10 mm, thickness No. 1.5H).</li>
		<li>Wash the glass with ddH2O, then with 70% EtOH and let them dry. Use one glass for each well of a 24-well plate.</li>
		<li>Add 200 &#181;L of 0.1% poly-L-lysine (w/v) (Table of Materials) directly on the glass to form a drop. Pay attention as the drop must remain on the glass surface without touching the well for 2&#8722;5 min. Leave out the drop carefully, and let the glass dry for 30 min.</li>
		<li>Perform step 2.1.3 twice more.</li>
		<li>Put 200 &#181;L of suspension cells (2 x 106/mL, PBS suspension of ex vivo primary T lymphocytes) directly on the glass, allow the cells to seed at room temperature (RT) for 30 min.</li>
		<li>Quickly remove the drop. Add freshly made 4% PFA (prepared in PBS/0.1% TWEEN 20, pH 7.0, filtered) for 10 min and fix the seeded cells at RT.</li>
		<li>Wash three times for 5 min each with 0.05% Triton X-100/PBS (TPBS) at RT. Permeabilize with 0.5% TPBS for 10 min at RT.</li>
		<li>Perform RNase treatment by adding 2.5 &#181;L of RNase cocktail (Table of Materials) in 250 &#181;L of PBS/well in a 24-well plate for 1 h at 37 &#176;C.</li>
		<li>Rinse in PBS, add 20% glycerol/PBS, and incubate overnight (ON) at 4 &#176;C. 
		NOTE: This step can range from 1 h to ON. Slides can be kept in 20% glycerol/PBS at 4 &#176;C up to 7 days.</li>
		<li>Freeze on dry ice (15&#8722;30 s), thaw gradually at RT, and soak in 20% glycerol/PBS. Repeat step 2.1.9 another three times.</li>
		<li>Wash in 0.5% TPBS for 5 min at RT. Wash in 0.05% TPBS, twice for 5 min at RT. Incubate in 0.1 N HCl for 12 min at RT. Rinse in 2x SSC.</li>
		<li>Incubate in 50% formamide pH 7.0/2x SSC ON at RT. 
		NOTE: The incubation time can be optimized and eventually reduced. Slides can be kept in 50% formamide/2x SSC for several days.</li>
	</ol>
	</li>
	<li>Cell fixation, pre-treatment and permeabilization for human primary myoblasts 
	NOTE: This protocol is suitable for large cells, with a high amount of cytoplasm.
	<ol>
		<li>Grow human primary myoblasts directly on the coverslip glasses in 24-well plates in growth medium (Dulbecco&#39;s modified Eagle medium (DMEM), 20% fetal bovine serum (FBS), 25 ng/mL fibroblast growth factor (FGF), 10 ng/mL epidermal growth factor (EGF), 10 &#181;g/mL human insulin, 1x glutamine, 1x penicillin/streptomycin) for at least 24 h (reaching 50&#8722;70% of confluence). 
		NOTE: To facilitate the adhesion, gelatin or collagen or poly-L-lysine can be used to coat the coverslip prior the seeding.</li>
		<li>Rinse cells in 2&#8722;3 changes of PBS. Add freshly made 4% PFA and fix the cells for 10 min at RT.</li>
		<li>Wash three times for 3 min each in 0.01% TPBS at RT. Permeabilize in 0.5% TPBS for 10 min at RT.</li>
		<li>Perform RNase treatment by adding 2.5 &#181;L of RNase cocktail (Table of Materials) in 250 &#181;L of PBS/well in a 24-well plate for 1 h at 37 &#176;C.</li>
		<li>Rinse in PBS, add 20% glycerol/PBS, and incubate ON at RT. 
		NOTE: This step can range from 1 h to ON. Slides can be kept in 20% glycerol/PBS at 4 &#176;C up to 7 days.</li>
		<li>Freeze on dry ice (15&#8722;30 s), thaw gradually at RT, and soak in 20% glycerol/PBS. Repeat this step three times.</li>
		<li>Wash three times for 10 min each in PBS. Incubate in 0.1 N HCl for 5 min at RT. Rinse in 2x SSC.</li>
		<li>Incubate in 50% formamide pH 7.0/2x SSC ON at RT. 
		NOTE: The time of incubation can be optimized and eventually reduced. Slides can be kept in 50% formamide/2x SSC for several days.</li>
		<li>Equilibrate slides (kept in 50% formamide/2x SSC) in 2x SSC for 2 min. Then, equilibrate in PBS for 3 min.</li>
		<li>Treat with 0.01 N HCl/0.0025% pepsin from a few seconds up to 5 min, depending on the cell type. During this step, observe the cells under an optical microscope and stop the reaction (step 2.2.11) as soon as the nuclei are free from the cytoplasm, while maintaining their structure intact (e.g., nucleoli are still visible and intact).</li>
		<li>Inactivate the pepsin by washing twice for 5 min each in 50 mM MgCl2/PBS.</li>
		<li>Post-fix in 1% PFA/PBS for 1 min. Wash for 5 min in PBS. Wash twice for 5 min each in 2x SSC, and then add 50% formamide/2x SSC for at least 30 min.</li>
	</ol>
	</li>
</ol>
3. 3D multicolor DNA FISH hybridization
<ol>
	<li>Denature the probes at 80 &#176;C for 5 min, and then put quickly on ice.</li>
	<li>Load the hybridization probes on a clean microscope slide. Turn the coverslip with cells upside down on the drop of hybridization probes.</li>
	<li>Seal the coverslip with rubber cement. Let the rubber cement dry completely. Then place slides on a heating block and denature at 75 &#176;C for 4 min. 
	NOTE: The timing of denaturation and temperature of denaturation can be augmented, up to 80 &#176;C.</li>
	<li>Hybridize at 37 &#176;C ON in a metallic box floating in a water bath. 
	NOTE: To improve the signal to noise ratio, the hybridization temperature can go up to 42 &#176;C.</li>
	<li>Peel off rubber cement, immerse the slides in 2x SCC, strip off the glass coverslip and transfer it to 2x SSC in 6-well plate.</li>
	<li>Wash in 2x SSC three times for 5 min each at 37 &#176;C, shaking at 90 rpm in an incubator shaker. Wash in 0.1x SSC three times for 5 min each at 60 &#176;C, shaking at 90 rpm in an incubator shaker. Rinse briefly in 4x SSC/0.2% TWEEN 20.</li>
</ol>
4. 3D multicolor DNA FISH detection
NOTE: For directly labelled probes, skip steps 4.1 and 4.2.
<ol>
	<li>Block in 4x SSC/0.2% TWEEN 20/4% bovine serum albumin (BSA) for 20 min at 37 &#176;C in a 24-well plate, shaking at 20 rpm in an incubator shaker.</li>
	<li>Incubate with the appropriate concentration of anti-digoxygenin (1:150), and/or streptavidin (1:1,000) (Table of Materials) diluted in 4x SSC/0.2% TWEEN 20/4% BSA for 35 min in a dark and wet chamber at 37 &#176;C.</li>
	<li>Wash in 4x SSC/0.2% TWEEN 20 three times for 5 min each at 37 &#176;C, shaking at 90 rpm in a 6-well plate in an incubator shaker.</li>
	<li>Equilibrate in PBS and post-fix in 2% formaldehyde/PBS for 2 min at RT in a 24-well plate. 
	NOTE: Directly labelled probes do not need post-fixation.</li>
	<li>Wash 5x briefly in PBS. Stain with 1 ng/mL DAPI (4,6-diamidino-2-phenylindole)/PBS for 5 min at RT.</li>
	<li>Wash 5x briefly in PBS. Mount with antifade solution (Table of Materials).</li>
</ol>
5. 3D multicolor DNA FISH microscopy and analysis
<ol>
	<li>Acquire 3D images with a microscope system. 
	NOTE: Here, a widefield microscope with an axial distance of 0.2&#8722;0.25 &#956;m between consecutive sections (Figure 1B) is used.</li>
	<li>Analyze 3D image stacks using different software and tools (here, NuCL&#949;D or Nuclear Contacts Locator in 3D). 
	NOTE: The tool NuCL&#949;D has been developed in order to automatically analyze 3D multicolor DNA FISH in fluorescence cell image z-stacks. NuCL&#949;D reconstructs the nuclei from cell image stacks in 3D as well as detects and localizes fluorescent 3D spots. It measures the relative positioning of spots in the nucleus (e.g., distance from the centroid of the nuclei and/or periphery of the nuclei) and the maximum radius for each nucleus and inter-spots distances. The tool and the algorithm used are fully described in Cortesi et al.16.</li>
	<li>Analyze the data (e.g., 3D distances between specified genomic loci and the nuclear centroid and contact frequencies) retrieved by NuCL&#949;D. 
	NOTE: For 3D distances between specified genomic loci and the nuclear centroid, normalize distances on the maximum radius for each nucleus and represent these data as frequency distributions of normalized distances from the nuclear centroid. For long range interactions studies, contact frequencies are supposed to be in the range of 10&#8722;20%21 with a threshold inter-distance that can vary and can be put around 2 &#181;m35.
	<ol>
		<li>To perform statistical analysis, analyze approximately 100 nuclei per biological replicate. Represent 3D distances between specified genomic loci as cumulative frequency distributions of distances that are below the threshold inter-distance selected and use a t-test to assess the significance of differences in the distributions. Also, calculate the percentage of nuclei positive for the interactions that are below the threshold inter-distance selected, and use Fisher&#39;s exact test to assess the significance of differences in the percentages.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Cremer, T., Cremer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromosome+territories,+nuclear+architecture+and+gene+regulation+in+mammalian+cells.">Chromosome territories, nuclear architecture and gene regulation in mammalian cells.</a> Nature Reviews: Genetics. 2 (4), 292-301 (2001).</li><li>Lieberman-Aiden, E., 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=Comprehensive+mapping+of+long-range+interactions+reveals+folding+principles+of+the+human+genome.">Comprehensive mapping of long-range interactions reveals folding principles of the human genome.</a> Science. 326 (5950), 289-293 (2009).</li><li>Schmitt, A. D., Hu, M., Ren, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome-wide+mapping+and+analysis+of+chromosome+architecture.">Genome-wide mapping and analysis of chromosome architecture.</a> Nature Reviews: Molecular Cell Biology. 17 (12), 743-755 (2016).</li><li>Bonev, B., Cavalli, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organization+and+function+of+the+3D+genome.">Organization and function of the 3D genome.</a> Nature Reviews: Genetics. 17 (12), 772 (2016).</li><li>van Steensel, B., Furlong, E. E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+transcription+in+shaping+the+spatial+organization+of+the+genome.">The role of transcription in shaping the spatial organization of the genome.</a> Nature Reviews: Molecular Cell Biology. 20 (6), 327-337 (2019).</li><li>Rajarajan, P., Gil, S. E., Brennand, K. J., Akbarian, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatial+genome+organization+and+cognition.">Spatial genome organization and cognition.</a> Nature Reviews: Neuroscience. 17 (11), 681-691 (2016).</li><li>Pombo, A., Dillon, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+genome+architecture:+players+and+mechanisms.">Three-dimensional genome architecture: players and mechanisms.</a> Nature Reviews: Molecular Cell Biology. 16 (4), 245-257 (2015).</li><li>Fanucchi, S., Shibayama, Y., Burd, S., Weinberg, M. S., Mhlanga, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromosomal+contact+permits+transcription+between+coregulated+genes.">Chromosomal contact permits transcription between coregulated genes.</a> Cell. 155 (3), 606-620 (2013).</li><li>Therizols, P., 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=Chromatin+decondensation+is+sufficient+to+alter+nuclear+organization+in+embryonic+stem+cells.">Chromatin decondensation is sufficient to alter nuclear organization in embryonic stem cells.</a> Science. 346 (6214), 1238-1242 (2014).</li><li>Gonzalez-Sandoval, 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=Perinuclear+Anchoring+of+H3K9-Methylated+Chromatin+Stabilizes+Induced+Cell+Fate+in+C.+elegans+Embryos.">Perinuclear Anchoring of H3K9-Methylated Chromatin Stabilizes Induced Cell Fate in C. elegans Embryos.</a> Cell. 163 (6), 1333-1347 (2015).</li><li>Hubner, 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=Remodeling+of+nuclear+landscapes+during+human+myelopoietic+cell+differentiation+maintains+co-aligned+active+and+inactive+nuclear+compartments.">Remodeling of nuclear landscapes during human myelopoietic cell differentiation maintains co-aligned active and inactive nuclear compartments.</a> Epigenetics Chromatin. 8, 47 (2015).</li><li>Aymard, F., 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=Genome-wide+mapping+of+long-range+contacts+unveils+clustering+of+DNA+double-strand+breaks+at+damaged+active+genes.">Genome-wide mapping of long-range contacts unveils clustering of DNA double-strand breaks at damaged active genes.</a> Nature Structural &amp; Molecular Biology. 24 (4), 353-361 (2017).</li><li>Sellou, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+poly(ADP-ribose)-dependent+chromatin+remodeler+Alc1+induces+local+chromatin+relaxation+upon+DNA+damage.">The poly(ADP-ribose)-dependent chromatin remodeler Alc1 induces local chromatin relaxation upon DNA damage.</a> Molecular Biology of the Cell. 27 (24), 3791-3799 (2016).</li><li>Krijger, P. H., de Laat, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+disease-associated+gene+expression+in+the+3D+genome.">Regulation of disease-associated gene expression in the 3D genome.</a> Nature Reviews: Molecular Cell Biology. 17 (12), 771-782 (2016).</li><li>Lupianez, D. G., Spielmann, M., Mundlos, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breaking+TADs:+How+Alterations+of+Chromatin+Domains+Result+in+Disease.">Breaking TADs: How Alterations of Chromatin Domains Result in Disease.</a> Trends in Genetics. 32 (4), 225-237 (2016).</li><li>Cortesi, 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=4q-D4Z4+chromatin+architecture+regulates+the+transcription+of+muscle+atrophic+genes+in+facioscapulohumeral+muscular+dystrophy.">4q-D4Z4 chromatin architecture regulates the transcription of muscle atrophic genes in facioscapulohumeral muscular dystrophy.</a> Genome Research. 29 (6), 883-895 (2019).</li><li>Woltering, J. M., Noordermeer, D., Leleu, M., Duboule, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conservation+and+divergence+of+regulatory+strategies+at+Hox+Loci+and+the+origin+of+tetrapod+digits.">Conservation and divergence of regulatory strategies at Hox Loci and the origin of tetrapod digits.</a> PLoS Biology. 12 (1), 1001773 (2014).</li><li>Woltering, J. M., Duboule, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tetrapod+axial+evolution+and+developmental+constraints;+Empirical+underpinning+by+a+mouse+model.">Tetrapod axial evolution and developmental constraints; Empirical underpinning by a mouse model.</a> Mechanisms of Development. 138, 64-72 (2015).</li><li>de Laat, W., Dekker, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3C-based+technologies+to+study+the+shape+of+the+genome.">3C-based technologies to study the shape of the genome.</a> Methods. 58 (3), 189-191 (2012).</li><li>Denker, A., de Laat, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+second+decade+of+3C+technologies:+detailed+insights+into+nuclear+organization.">The second decade of 3C technologies: detailed insights into nuclear organization.</a> Genes &amp; Development. 30 (12), 1357-1382 (2016).</li><li>Finn, E. H., 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=Extensive+Heterogeneity+and+Intrinsic+Variation+in+Spatial+Genome+Organization.">Extensive Heterogeneity and Intrinsic Variation in Spatial Genome Organization.</a> Cell. 176 (6), 1502-1515 (2019).</li><li>Zheng, 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=Multiplex+chromatin+interactions+with+single-molecule+precision.">Multiplex chromatin interactions with single-molecule precision.</a> Nature. 566 (7745), 558-562 (2019).</li><li>Solovei, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+in+situ+hybridization+(FISH)+on+tissue+cryosections.">Fluorescence in situ hybridization (FISH) on tissue cryosections.</a> Methods in Molecular Biology. 659, 71-82 (2010).</li><li>Cremer, 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=Multicolor+3D+fluorescence+in+situ+hybridization+for+imaging+interphase+chromosomes.">Multicolor 3D fluorescence in situ hybridization for imaging interphase chromosomes.</a> Methods in Molecular Biology. 463, 205-239 (2008).</li><li>Legant, W. 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=High-density+three-dimensional+localization+microscopy+across+large+volumes.">High-density three-dimensional localization microscopy across large volumes.</a> Nature Methods. 13 (4), 359-365 (2016).</li><li>Jungmann, 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=Quantitative+super-resolution+imaging+with+qPAINT.">Quantitative super-resolution imaging with qPAINT.</a> Nature Methods. 13 (5), 439-442 (2016).</li><li>Chen, 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=Dynamic+imaging+of+genomic+loci+in+living+human+cells+by+an+optimized+CRISPR/Cas+system.">Dynamic imaging of genomic loci in living human cells by an optimized CRISPR/Cas system.</a> Cell. 155 (7), 1479-1491 (2013).</li><li>Nelles, D. 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=Programmable+RNA+Tracking+in+Live+Cells+with+CRISPR/Cas9.">Programmable RNA Tracking in Live Cells with CRISPR/Cas9.</a> Cell. 165 (2), 488-496 (2016).</li><li>Byron, M., Hall, L. L., Lawrence, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+multifaceted+FISH+approach+to+study+endogenous+RNAs+and+DNAs+in+native+nuclear+and+cell+structures.">A multifaceted FISH approach to study endogenous RNAs and DNAs in native nuclear and cell structures.</a> Current Protocol of Human Genetics. , 15 (2013).</li><li>Chaumeil, J., Augui, S., Chow, J. C., Heard, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combined+immunofluorescence,+RNA+fluorescent+in+situ+hybridization,+and+DNA+fluorescent+in+situ+hybridization+to+study+chromatin+changes,+transcriptional+activity,+nuclear+organization,+and+X-chromosome+inactivation.">Combined immunofluorescence, RNA fluorescent in situ hybridization, and DNA fluorescent in situ hybridization to study chromatin changes, transcriptional activity, nuclear organization, and X-chromosome inactivation.</a> Methods in Molecular Biology. 463, 297-308 (2008).</li><li>Takizawa, T., Gudla, P. R., Guo, L., Lockett, S., Misteli, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allele-specific+nuclear+positioning+of+the+monoallelically+expressed+astrocyte+marker+GFAP.">Allele-specific nuclear positioning of the monoallelically expressed astrocyte marker GFAP.</a> Genes &amp; Development. 22 (4), 489-498 (2008).</li><li>Kraus, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+3D+structured+illumination+microscopy+of+nuclear+structures.">Quantitative 3D structured illumination microscopy of nuclear structures.</a> Nature Protocols. 12 (5), 1011-1028 (2017).</li><li>Solovei, I., Cremer, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D-FISH+on+cultured+cells+combined+with+immunostaining.">3D-FISH on cultured cells combined with immunostaining.</a> Methods in Molecular Biology. 659, 117-126 (2010).</li><li>Skinner, B. M., Johnson, E. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nuclear+morphologies:+their+diversity+and+functional+relevance.">Nuclear morphologies: their diversity and functional relevance.</a> Chromosoma. 126 (2), 195-212 (2017).</li><li>Schoenfelder, 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=The+pluripotent+regulatory+circuitry+connecting+promoters+to+their+long-range+interacting+elements.">The pluripotent regulatory circuitry connecting promoters to their long-range interacting elements.</a> Genome Research. 25 (4), 582-597 (2015).</li><li>Lubeck, E., Cai, L. <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+systems+biology+by+super-resolution+imaging+and+combinatorial+labeling.">Single-cell systems biology by super-resolution imaging and combinatorial labeling.</a> Nature Methods. 9 (7), 743-748 (2012).</li><li>Beliveau, B. 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=Single-molecule+super-resolution+imaging+of+chromosomes+and+in+situ+haplotype+visualization+using+Oligopaint+FISH+probes.">Single-molecule super-resolution imaging of chromosomes and in situ haplotype visualization using Oligopaint FISH probes.</a> Nature Communication. 6, 7147 (2015).</li><li>Beliveau, B. 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=Versatile+design+and+synthesis+platform+for+visualizing+genomes+with+Oligopaint+FISH+probes.">Versatile design and synthesis platform for visualizing genomes with Oligopaint FISH probes.</a> Proceedings of the National Academy of Sciences. 109 (52), 21301-21306 (2012).</li><li>Samacoits, 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=A+computational+framework+to+study+sub-cellular+RNA+localization.">A computational framework to study sub-cellular RNA localization.</a> Nature Communication. 9 (1), 4584 (2018).</li><li>Cardozo Gizzi, 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=Microscopy-Based+Chromosome+Conformation+Capture+Enables+Simultaneous+Visualization+of+Genome+Organization+and+Transcription+in+Intact+Organisms.">Microscopy-Based Chromosome Conformation Capture Enables Simultaneous Visualization of Genome Organization and Transcription in Intact Organisms.</a> Molecular Cell. 74 (1), 212-222 (2019).</li><li>Mateo, L. 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=Visualizing+DNA+folding+and+RNA+in+embryos+at+single-cell+resolution.">Visualizing DNA folding and RNA in embryos at single-cell resolution.</a> Nature. 568 (7750), 49-54 (2019).</li><li>Nir, G., 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=Walking+along+chromosomes+with+super-resolution+imaging,+contact+maps,+and+integrative+modeling.">Walking along chromosomes with super-resolution imaging, contact maps, and integrative modeling.</a> PLoS Genetics. 14 (12), 1007872 (2018).</li><li>Bintu, 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=Super-resolution+chromatin+tracing+reveals+domains+and+cooperative+interactions+in+single+cells.">Super-resolution chromatin tracing reveals domains and cooperative interactions in single cells.</a> Science. 362 (6413), (2018).</li></ol>

The authors have nothing to disclose.

The current method describes a step by step protocol to perform 3D multicolor DNA FISH on a wide range of human primary cells. Although DNA FISH is a technology in wide use, 3D multicolor DNA FISH on preserved 3D interphase nuclei is still difficult to perform in many laboratories, mainly due to the characteristics of the samples used23,24.
Probe nick translation is a fundamental step for successful 3D multicolor DNA FISH; many differe...

Higher eukaryotes need to systematically condense and compact a huge amount of genetic information in the minute 3D space of the nucleus1,2,3,4. Today, we know that the genome is spatially ordered in compartments and topologically associated domains5 and that the multiple levels of DNA folding generate contacts between different genomic regions that may involve chromatin loop formation6,7. The 3D dynamic looping of chromatin can influence many different biological processes such as transcription8,9, differentiation and development10,11, DNA repair12,13, while its perturbations are involved in various diseases14,15,16 and developmental defects15,17,18.
Many approaches have been developed to study the 3D genome organization. Chromosome conformation capture-based technologies (C-technologies, 3C, 4C, 5C, Hi-C and derivatives) have been developed to study genome organization in fixed cells3,4,19,20. Such approaches are based on the ability to capture the contact frequencies between genomic loci in physical proximity. C-technologies, depending on their complexity, catch the global 3D genome organization and nuclear topology of a cell population3,4,19,20. Nevertheless, 3D interactions are dynamic in time and space, highly variable between individual cells consisting of multiplex interactions, and are extensively heterogenous21,22.
3D multicolor DNA fluorescence in situ hybridization (FISH) is a technique that allows the visualization of specific genomic loci at a single cell level, enabling direct investigation of the 3D nuclear architecture in a complementary manner to C-technologies. It represents a technology currently used to unambiguously validate C-results. 3D multicolor DNA FISH uses fluorescently labeled probes complementary to the genomic loci of interests. The use of different fluorophores and suitable microscopy equipment allow contemporary visualization of multiple targets within the nuclear space23,24. In recent years, FISH has been combined with technological advances in microscopy to obtain the visualization of fine-scale structures at high resolution25,26 or with CRISPR-Cas approaches for the visualization of the nucleic acids in live imaging27,28. Despite wide adoption, the 3D multicolor DNA FISH approach is still considered difficult in many laboratories because the biological material used must be adapted.
Here, we provide a comprehensive protocol for 3D multicolor DNA FISH (from cell/probe preparation to data analysis) applicable to a wide range of human primary cells, enabling the visualization of multiple genomic loci and preserving the 3D structure of nuclei. In order to study nuclear architecture, the 3D structure of nuclei must be preserved. For this reason, contrasting from other existing protocols29,30,31, we avoid the use of an alcohol gradient and the storage of the coverslips in alcohol that can affect chromatin structure32. The method is adapted from preserved 3D DNA FISH protocols24,33 to be applied to a wide range of human primary cells, both isolated ex vivo or cultured in vitro. There are permeabilization and deproteinization parameters for different nuclear morphology and cytological characteristics (e.g., different degrees of nuclear compaction, cytoskeleton abundance)34. These parameters are often generally described in other protocols24,33, without providing a clear discrimination of the procedure within different cell types. Furthermore, we developed a specific tool named NuCL&#949;D (nuclear contacts locator in 3D)16, providing principles for data analysis that will improve the 3D proximity between different loci and their nuclear topological distribution within the nuclear space in an automated way.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>24-well plates</td>
			<td>Thermo Fisher Scientific</td>
			<td>142475</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well plates</td>
			<td>Thermo Fisher Scientific</td>
			<td>140675</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Digoxigenin 488</td>
			<td>DBA</td>
			<td>DI7488</td>
			<td></td>
		</tr>
		<tr>
			<td>b-Mercaptoethanol</td>
			<td>Sigma</td>
			<td>M3148</td>
			<td></td>
		</tr>
		<tr>
			<td>bFGF</td>
			<td>PeproTech</td>
			<td>100-18B</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotin 11 d-UTP</td>
			<td>Thermo Fisher Scientific</td>
			<td>R0081</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA (bovine serum albumine)</td>
			<td>Sigma</td>
			<td>A7030</td>
			<td></td>
		</tr>
		<tr>
			<td>Coverlsips</td>
			<td>Marienfeld</td>
			<td>117500</td>
			<td></td>
		</tr>
		<tr>
			<td>CY3 d-UTP</td>
			<td>GE Healthcare</td>
			<td>PA53022</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI (4,6-diamidino-2-phenylindole)</td>
			<td>Thermo Fisher Scientific</td>
			<td>D21490</td>
			<td></td>
		</tr>
		<tr>
			<td>Deoxyribonucleic acids single strand from salmon testes</td>
			<td>Sigma</td>
			<td>D7656</td>
			<td></td>
		</tr>
		<tr>
			<td>Dextran sulfate (powder)</td>
			<td>Santa Cruz</td>
			<td>sc-203917A</td>
			<td></td>
		</tr>
		<tr>
			<td>Digoxigenin 11 d-UTP</td>
			<td>Roche</td>
			<td>11093088910</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>21969-035 500mL</td>
			<td></td>
		</tr>
		<tr>
			<td>DNA polymerase I</td>
			<td>Thermo Fisher Scientific</td>
			<td>18010-017</td>
			<td></td>
		</tr>
		<tr>
			<td>DNase I</td>
			<td>Sigma</td>
			<td>AMPD1</td>
			<td></td>
		</tr>
		<tr>
			<td>dNTPs (C-G-A-T)</td>
			<td>Euroclone</td>
			<td>BL0423A/C/G</td>
			<td></td>
		</tr>
		<tr>
			<td>EGF</td>
			<td>Sigma</td>
			<td>E9644.2MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma</td>
			<td>02860-1L</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS Hyclone</td>
			<td>Thermo Fisher Scientific</td>
			<td>SH30109</td>
			<td></td>
		</tr>
		<tr>
			<td>Formaldehyde solution</td>
			<td>Sigma</td>
			<td>F8775-25mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Formamide</td>
			<td>Sigma</td>
			<td>F9037</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutammine</td>
			<td>Thermo Fisher Scientific</td>
			<td>25030-024 100mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma</td>
			<td>G5516-100mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycogen</td>
			<td>Thermo Fisher Scientific</td>
			<td>AM9510</td>
			<td></td>
		</tr>
		<tr>
			<td>HCl</td>
			<td>Sigma</td>
			<td>30721</td>
			<td></td>
		</tr>
		<tr>
			<td>Human Cot-1 DNA</td>
			<td>Thermo Fisher Scientific</td>
			<td>15279-001</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin Human</td>
			<td>Sigma</td>
			<td>I9278-5 mL</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sigma</td>
			<td>63069</td>
			<td></td>
		</tr>
		<tr>
			<td>NaAc (Sodium Acetate, pH 5.2, 3 M)</td>
			<td>Sigma</td>
			<td>S2889</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma</td>
			<td>S9888</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma</td>
			<td>158127-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS (phosphate-buffered saline)</td>
			<td>Sigma</td>
			<td>P4417</td>
			<td></td>
		</tr>
		<tr>
			<td>Pennycillin/Streptavidin</td>
			<td>Thermo Fisher Scientific</td>
			<td>15070-063 100mL</td>
			<td></td>
		</tr>
		<tr>
			<td>Pepsin</td>
			<td>Biorad</td>
			<td>P6887</td>
			<td></td>
		</tr>
		<tr>
			<td>PhasePrep BAC DNA Kit</td>
			<td>Sigma</td>
			<td>NA0100-1KT</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-L-lysine solution</td>
			<td>Sigma</td>
			<td>P8920</td>
			<td></td>
		</tr>
		<tr>
			<td>ProLong Diamond Antifade Mountant</td>
			<td>Thermo Fisher Scientific</td>
			<td>P36970</td>
			<td></td>
		</tr>
		<tr>
			<td>PureLink Quick Gel Extraction &#38; PCR Purification Combo Kit</td>
			<td>Thermo Fisher Scientific</td>
			<td>K220001</td>
			<td></td>
		</tr>
		<tr>
			<td>PureLink Quick Plasmid Miniprep Kit</td>
			<td>Thermo Fisher Scientific</td>
			<td>K210010</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAse cocktail</td>
			<td>Thermo Fisher Scientific</td>
			<td>AM2288</td>
			<td></td>
		</tr>
		<tr>
			<td>Rubbercement</td>
			<td>Bostik</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Slides</td>
			<td>VWR</td>
			<td>631-0114</td>
			<td></td>
		</tr>
		<tr>
			<td>Streptavidina Alexa fluor 647</td>
			<td>Thermo Fisher Scientific</td>
			<td>S21374</td>
			<td></td>
		</tr>
		<tr>
			<td>Tri-Sodium Citrate</td>
			<td>Sigma</td>
			<td>1110379026</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris-HCl</td>
			<td>Sigma</td>
			<td>T3253-500g</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma</td>
			<td>T8787-250mL</td>
			<td></td>
		</tr>
		<tr>
			<td>TWEEN 20</td>
			<td>Sigma</td>
			<td>P9416-100mL</td>
			<td></td>
		</tr>
	</tbody>
</table>

3d multicolor dna fish tool to study nuclear architecture in human primary cells

A major question in cell biology is genomic organization within the nuclear space and how chromatin architecture can influence processes such as gene expression, cell identity and differentiation. Many approaches developed to study the 3D architecture of the genome can be divided into two complementary categories: chromosome conformation capture based technologies (C-technologies) and imaging. While the former is based on capturing the chromosome conformation and proximal DNA interactions in a population of fixed cells, the latter, based on DNA fluorescence in situ hybridization (FISH) on 3D-preserved nuclei, allows contemporary visualization of multiple loci at a single cell level (multicolor), examining their interactions and distribution within the nucleus (3D multicolor DNA FISH). The technique of 3D multicolor DNA FISH has a limitation of visualizing only a few predetermined loci, not permitting a comprehensive analysis of the nuclear architecture. However, given the robustness of its results, 3D multicolor DNA FISH in combination with 3D-microscopy and image reconstruction is a possible method to validate C-technology based results and to unambiguously study the position and organization of specific loci at a single cell level. Here, we propose a step by step method of 3D multicolor DNA FISH suitable for a wide range of human primary cells and discuss all the practical actions, crucial steps, notions of 3D imaging and data analysis needed to obtained a successful and informative 3D multicolor DNA FISH within different biological contexts.

The method of 3D multicolor DNA FISH described in this article allows contemporary visualization of different genomic loci within preserved 3D nuclei (Figure 1B). This protocol permits the measurement of distances between alleles, and different genomic loci in order to evaluate their spatial proximity, and to assess their location within the nuclear space (e.g., loci distance from the centroid or the periphery of the nuclei)16. However, there are many...

Watch this Scientific Journal Video about 3D Multicolor DNA FISH Tool to Study Nuclear Architecture in Human Primary Cells at JoVE.com

3D Multicolor DNA FISH Tool to Study Nuclear Architecture in Human Primary Cells

3D multicolor DNA FISH represents a tool to visualize multiple genomic loci within 3D preserved nuclei, unambiguously defining their reciprocal interactions and localization within the nuclear space at a single cell level. Here, a step by step protocol is described for a wide spectrum of human primary cells.

A major question in cell biology is genomic organization within the nuclear space and how chromatin architecture can influence processes such as gene ...

3d-multicolor-dna-fish-tool-to-study-nuclear-architecture-human

Universidad de Cartagena UDEC

Research

JoVE Journal

Genetics

10.2K Views.  Istituto Nazionale di Genetica Molecolare "Romeo ed Enrica Invernizzi", INGM. 3D multicolor DNA FISH represents a tool to visualize multiple genomic loci within 3D preserved nuclei, unambiguously defining their reciprocal interactions and localization within the nuclear space at a single cell level. Here, a step by step protocol is described for a wide spectrum of human primary cells.

Video: 3D Multicolor DNA FISH Tool to Study Nuclear Architecture in Human Primary Cells

Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures

Circadian clocks are functional in all light-sensitive organisms, allowing for an adaptation to the external world by anticipating daily environmental changes. Considerable progress in our understanding of the tight connection between the circadian clock and most aspects of physiology has been made in the field over the last decade. However, unraveling the molecular basis that underlies the function of the circadian oscillator in humans stays of highest technical challenge. Here, we provide a detailed description of an experimental approach for long-term (2-5 days) bioluminescence recording and outflow medium collection in cultured human primary cells. For this purpose, we have transduced primary cells with a lentiviral luciferase reporter that is under control of a core clock gene promoter, which allows for the parallel assessment of hormone secretion and circadian bioluminescence. Furthermore, we describe the conditions for disrupting the circadian clock in primary human cells by transfecting siRNA targeting CLOCK. Our results on the circadian regulation of insulin secretion by human pancreatic islets, and myokine secretion by human skeletal muscle cells, are presented here to illustrate the application of this methodology. These settings can be used to study the molecular makeup of human peripheral clocks and to analyze their functional impact on primary cells under physiological or pathophysiological conditions.

Here, we describe settings to monitor in parallel circadian bioluminescence and the secretory activity of human islet cells and primary myotubes. For this, we employed lentiviral gene delivery of a luciferase core clock reporter, followed by in vitro synchronization and collection of outflow medium by continuous cell perifusion.

Circadian clocks are functional in all light-sensitive organisms, allowing for an adaptation to the external world by anticipating daily environmental ...

Engineering Artificial Factors to Specifically Manipulate Alternative Splicing in Human Cells

The processing of most eukaryotic RNAs is mediated by RNA Binding Proteins (RBPs) with modular configurations, including an RNA recognition module, which specifically binds the pre-mRNA target and an effector domain. Previously, we have taken advantage of the unique RNA binding mode of the PUF domain in human Pumilio 1 to generate a programmable RNA binding scaffold, which was used to engineer various artificial RBPs to manipulate RNA metabolism. Here, a detailed protocol is described to construct Engineered Splicing Factors (ESFs) that are specifically designed to modulate the alternative splicing of target genes. The protocol includes how to design and construct a customized PUF scaffold for a specific RNA target, how to construct an ESF expression plasmid by fusing a designer PUF domain and an effector domain, and how to use ESFs to manipulate the splicing of target genes. In the representative results of this method, we have also described the common assays of ESF activities using splicing reporters, the application of ESF in cultured human cells, and the subsequent effect of splicing changes. By following the detailed protocols in this report, it is possible to design and generate ESFs for the regulation of different types of Alternative Splicing (AS), providing a new strategy to study splicing regulation and the function of different splicing isoforms. Moreover, by fusing different functional domains with a designed PUF domain, researchers can engineer artificial factors that target specific RNAs to manipulate various steps of RNA processing.

This report describes a bioengineering method to design and construct novel Artificial Splicing Factors (ASFs) that specifically modulate the splicing of target genes in mammalian cells. This method can be further expanded to engineer various artificial factors to manipulate other aspects of RNA metabolism.

The processing of most eukaryotic RNAs is mediated by RNA Binding Proteins (RBPs) with modular configurations, including an RNA recognition module, which ...

Laser Microirradiation to Study In Vivo Cellular Responses to Simple and Complex DNA Damage

DNA damage induces specific signaling and repair responses in the cell, which is critical for protection of genome integrity. Laser microirradiation became a valuable experimental tool to investigate the DNA damage response (DDR) in vivo. It allows real-time high-resolution single-cell analysis of macromolecular dynamics in response to laser-induced damage confined to a submicrometer region in the cell nucleus. However, various laser conditions have been used without appreciation of differences in the types of damage induced. As a result, the nature of the damage is often not well characterized or controlled, causing apparent inconsistencies in the recruitment or modification profiles. We demonstrated that different irradiation conditions (i.e., different wavelengths as well as different input powers (irradiances) of a femtosecond (fs) near-infrared (NIR) laser) induced distinct DDR and repair protein assemblies. This reflects the type of DNA damage produced. This protocol describes how titration of laser input power allows induction of different amounts and complexities of DNA damage, which can easily be monitored by detection of base and crosslinking damages, differential poly (ADP-ribose) (PAR) signaling, and pathway-specific repair factor assemblies at damage sites. Once the damage conditions are determined, it is possible to investigate the effects of different damage complexity and differential damage signaling as well as depletion of upstream factor(s) on any factor of interest.

Laser Microirradiation to Study In Vivo Cellular Responses to Simple and Complex DNA Damage

The goal of this protocol is to describe how to use laser microirradiation to induce different types of DNA damage, including relatively simple strand breaks and complex damage, to study DNA damage signaling and repair factor assembly at damage sites in vivo.

DNA damage induces specific signaling and repair responses in the cell, which is critical for protection of genome integrity. Laser microirradiation ...

Immunostaining for DNA Modifications: Computational Analysis of Confocal Images

For several decades, 5-methylcytosine (5mC) has been thought to be the only DNA modification with a functional significance in metazoans. The discovery of enzymatic oxidation of 5mC to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) as well as detection of N6-methyladenine (6mA) in the DNA of multicellular organisms provided additional degrees of complexity to the epigenetic research. According to a growing body of experimental evidence, these novel DNA modifications may play specific roles in different cellular and developmental processes. Importantly, as some of these marks (e. g. 5hmC, 5fC and 5caC) exhibit tissue- and developmental stage-specific occurrence in vertebrates, immunochemistry represents an important tool allowing assessment of spatial distribution of DNA modifications in different biological contexts. Here the methods for computational analysis of DNA modifications visualized by immunostaining followed by confocal microscopy are described. Specifically, the generation of 2.5 dimension (2.5D) signal intensity plots, signal intensity profiles, quantification of staining intensity in multiple cells and determination of signal colocalization coefficients are shown. Collectively, these techniques may be operational in evaluating the levels and localization of these DNA modifications in the nucleus, contributing to elucidating their biological roles in metazoans.

Newly discovered oxidized forms of 5-methylcytosine (oxi-mCs), 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) may represent distinct DNA modifications with unique functional roles. Here a semi-quantitative workflow for visualization of oxi-mCs' spatial distribution, signal intensity profiling and colocalization is described.

For several decades, 5-methylcytosine (5mC) has been thought to be the only DNA modification with a functional significance in metazoans. The discovery of ...

Highly Efficient Gene Disruption of Murine and Human Hematopoietic Progenitor Cells by CRISPR/Cas9

Advances in the hematopoietic stem cell (HSCs) field have been aided by methods to genetically engineer primary progenitor cells as well as animal models. Complete gene ablation in HSCs required the generation of knockout mice from which HSCs could be isolated, and gene ablation in primary human HSCs was not possible. Viral transduction could be used for knock-down approaches, but these suffered from variable efficacy. In general, genetic manipulation of human and mouse hematopoietic cells was hampered by low efficiencies and extensive time and cost commitments. Recently, CRISPR/Cas9 has dramatically expanded the ability to engineer the DNA of mammalian cells. However, the application of CRISPR/Cas9 to hematopoietic cells has been challenging, mainly due to their low transfection efficiencies, the toxicity of plasmid-based approaches and the slow turnaround time of virus-based protocols.
A rapid method to perform CRISPR/Cas9-mediated gene editing in murine and human hematopoietic stem and progenitor cells with knockout efficiencies of up to 90% is provided in this article. This approach utilizes a ribonucleoprotein (RNP) delivery strategy with a streamlined three-day workflow. The use of Cas9-sgRNA RNP allows for a hit-and-run approach, introducing no exogenous DNA sequences in the genome of edited cells and reducing off-target effects. The RNP-based method is fast and straightforward: it does not require cloning of sgRNAs, virus preparation or specific sgRNA chemical modification. With this protocol, scientists should be able to successfully generate knockouts of a gene of interest in primary hematopoietic cells within a week, including downtimes for oligonucleotide synthesis. This approach will allow a much broader group of users to adapt this protocol for their needs.

A protocol for fast CRISPR/Cas9-mediated gene disruption in mouse and human primary hematopoietic cells is described in this article. Cas9-sgRNA ribonucleoproteins are introduced via electroporation with sgRNAs generated through in vitro transcription and commercial Cas9. High editing efficiencies are achieved with limited time and financial cost.

Advances in the hematopoietic stem cell (HSCs) field have been aided by methods to genetically engineer primary progenitor cells as well as animal models. ...

ATAC-seq Assay with Low Mitochondrial DNA Contamination from Primary Human CD4+ T Lymphocytes

ATAC-seq has become a widely used methodology in the study of epigenetics due to its rapid and simple approach to mapping genome-wide accessible chromatin. In this paper we present an improved ATAC-seq protocol that reduces contaminating mitochondrial DNA reads. While previous ATAC-seq protocols have struggled with an average of 50% contaminating mitochondrial DNA reads, the optimized&#160;lysis buffer introduced in this protocol reduces mitochondrial DNA contamination to an average of 3%. This improved ATAC-seq protocol allows for a near 50% reduction in the sequencing cost. We demonstrate how these high-quality ATAC-seq libraries can be prepared from activated CD4+ lymphocytes, providing step-by-step instructions from CD4+ lymphocyte isolation from whole blood through data analysis. This improved ATAC-seq protocol has been validated in a wide range of cell types and will be of immediate use to researchers studying chromatin accessibility.

Here, we present a protocol to perform an assay for transposase-accessible chromatin sequencing (ATAC-seq) on activated CD4+ human lymphocytes. The protocol has been modified to minimize contaminating mitochondrial DNA reads from 50% to 3% through the introduction of a new lysis buffer.

ATAC-seq has become a widely used methodology in the study of epigenetics due to its rapid and simple approach to mapping genome-wide accessible ...

Enhanced Yeast One-hybrid Screens To Identify Transcription Factor Binding To Human DNA Sequences

Identifying the sets of transcription factors (TFs) that regulate each human gene is a daunting task that requires integrating numerous experimental and computational approaches. One such method is the yeast one-hybrid (Y1H) assay, in which interactions between TFs and DNA regions are tested in the milieu of the yeast nucleus using reporter genes. Y1H assays involve two components: a &#8216;DNA-bait&#8217; (e.g., promoters, enhancers, silencers, etc.) and a &#8216;TF-prey,&#8217; which can be screened for reporter gene activation. Most published protocols for performing Y1H screens are based on transforming TF-prey libraries or arrays into DNA-bait yeast strains. Here, we describe a pipeline, called enhanced Y1H (eY1H) assays, where TF-DNA interactions are interrogated by mating DNA-bait strains with an arrayed collection of TF-prey strains using a high density array (HDA) robotic platform that allows screening in a 1,536 colony format. This allows for a dramatic increase in throughput (60 DNA-bait sequences against &#62;1,000 TFs takes two weeks per researcher) and reproducibility. We illustrate the different types of expected results by testing human promoter sequences against an array of 1,086 human TFs, as well as examples of issues that can arise during screens and how to troubleshoot them.

Here, we present an enhanced yeast one-hybrid screening protocol to identify the transcription factors (TFs) that can bind to a human DNA region of interest. This method uses a high-throughput screening pipeline that can interrogate the binding of &#62;1,000 TFs in a single experiment.

Identifying the sets of transcription factors (TFs) that regulate each human gene is a daunting task that requires integrating numerous experimental and ...

Multi-locus Variable-number Tandem-repeat Analysis of the Fish-pathogenic Bacterium Yersinia ruckeri by Multiplex PCR and Capillary Electrophoresis

Yersinia ruckeri is an important pathogen of farmed salmonids worldwide, but simple tools suitable for epizootiological investigations (infection tracing, etc.) of this bacterium have been lacking. A Multi-Locus Variable-number tandem-repeat Analysis (MLVA) assay was therefore developed as an easily accessible and unambiguous tool for high-resolution genotyping of recovered isolates. For the MLVA assay presented here, DNA is extracted from cultured Y. ruckeri samples by boiling bacterial cells in water, followed by use of supernatant as template for PCR. Primer-pairs targeting ten Variable-number tandem-repeat (VNTR) loci, interspersed throughout the Y. ruckeri genome, are distributed equally amongst two five-plex PCR reactions running under identical cycling conditions. Forward primers are labelled with either of three fluorescent dyes. Following amplicon confirmation by gel electrophoresis, PCR products are diluted and subjected to capillary electrophoresis. From the resulting electropherogram profiles, peaks representing each of the VNTR loci are size-called and employed for calculating VNTR repeat counts in silico. Resulting ten-digit MLVA profiles are then&#160;used to generate Minimum spanning trees enabling epizootiological evaluation by cluster analysis. The highly portable output data, in the form of numerical MLVA profiles, can rapidly be compared across labs and placed in a spatiotemporal context. The entire procedure from cultured colony to epizootiological evaluation may be completed for up to 48 Y. ruckeri isolates within a single working day.

Multi-locus Variable-number Tandem-repeat Analysis of the Fish-pathogenic Bacterium Yersinia ruckeri by Multiplex PCR and Capillary Electrophoresis

The Multi-Locus Variable-number tandem-repeat Analysis (MLVA) assay presented here enables inexpensive, robust and portable high-resolution genotyping of the fish-pathogenic bacterium Yersinia ruckeri. Starting from pure cultures, the assay employs multiplex PCR and capillary electrophoresis to produce ten-loci MLVA profiles for downstream applications.

Yersinia ruckeri is an important pathogen of farmed salmonids worldwide, but simple tools suitable for epizootiological investigations (infection tracing, ...

Navigating MARRVEL, a Web-Based Tool that Integrates Human Genomics and Model Organism Genetics Information

Through whole-exome/genome sequencing, human geneticists identify rare variants that segregate with disease phenotypes. To assess if a specific variant is pathogenic, one must query many databases to determine whether the gene of interest is linked to a genetic disease, whether the specific variant has been reported before, and what functional data is available in model organism databases that may provide clues about the gene&#8217;s function in human. MARRVEL (Model organism Aggregated Resources for Rare Variant ExpLoration) is a one-stop data collection tool for human genes and variants and their orthologous genes in seven model organisms including in mouse, rat, zebrafish, fruit fly, nematode worm, fission yeast, and budding yeast. In this Protocol, we provide an overview of what MARRVEL can be used for and discuss how different datasets can be used to assess whether a variant of unknown significance (VUS) in a known disease-causing gene or a variant in a gene of uncertain significance (GUS) may be pathogenic. This protocol will guide a user through searching multiple human databases simultaneously starting with a human gene with or without a variant of interest. We also discuss how to utilize data from OMIM, ExAC/gnomAD, ClinVar, Geno2MP, DGV and DECHIPHER. Moreover, we illustrate how to interpret a list of ortholog candidate genes, expression patterns, and GO terms in model organisms associated with each human gene. Furthermore, we discuss the value protein structural domain annotations provided and explain how to use the multiple species protein alignment feature to assess whether a variant of interest affects an evolutionarily conserved domain or amino acid. Finally, we will discuss three different use-cases of this website. MARRVEL is an easily accessible open access website designed for both clinical and basic researchers and serves as a starting point to design experiments for functional studies.

Here, we present a protocol to access and analyze many human and model organism databases efficiently. This protocol demonstrates the use of MARRVEL to analyze candidate disease-causing variants identified from next-generation sequencing efforts.

Through whole-exome/genome sequencing, human geneticists identify rare variants that segregate with disease phenotypes. To assess if a specific variant is ...

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila

Advances in sequencing technology have made whole-genome and whole-exome datasets more accessible for both clinical diagnosis and cutting-edge human genetics research. Although a number of in silico algorithms have been developed to predict the pathogenicity of variants identified in these datasets, functional studies are critical to determining how specific genomic variants affect protein function, especially for missense variants. In the Undiagnosed Diseases Network (UDN) and other rare disease research consortia, model organisms (MO) including Drosophila, C. elegans, zebrafish, and mice are actively used to assess the function of putative human disease-causing variants. This protocol describes a method for the functional assessment of rare human variants used in the Model Organisms Screening Center Drosophila Core of the UDN. The workflow begins with gathering human and MO information from multiple public databases, using the MARRVEL web resource to assess whether the variant is likely to contribute to a patient&#39;s condition as well as design effective experiments based on available knowledge and resources. Next, genetic tools (e.g., T2A-GAL4 and UAS-human cDNA lines) are generated to assess the functions of variants of interest in Drosophila. Upon development of these reagents, two-pronged functional assays based on rescue and overexpression experiments can be performed to assess variant function. In the rescue branch, the endogenous fly genes are &#34;humanized&#34;&#160;by replacing the orthologous Drosophila gene with reference or variant human transgenes. In the overexpression branch, the reference and variant human proteins are exogenously driven in a variety of tissues. In both cases, any scorable phenotype (e.g., lethality, eye morphology, electrophysiology) can be used as a read-out, irrespective of the disease of interest. Differences observed between reference and variant alleles suggest a variant-specific effect, and thus likely pathogenicity. This protocol allows rapid, in vivo assessments of putative human disease-causing variants of genes with known and unknown functions.

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila

The goal of this protocol is to outline the design and performance of in vivo experiments in Drosophila melanogaster to assess the functional consequences of rare gene variants associated with human diseases.

Advances in sequencing technology have made whole-genome and whole-exome datasets more accessible for both clinical diagnosis and cutting-edge human ...

3D Multicolor DNA FISH Tool to Study Nuclear Architecture in Human Primary Cells

Summary

Explore More Videos

Chapters in this video

Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures

Engineering Artificial Factors to Specifically Manipulate Alternative Splicing in Human Cells

Laser Microirradiation to Study In Vivo Cellular Responses to Simple and Complex DNA Damage

Immunostaining for DNA Modifications: Computational Analysis of Confocal Images

Highly Efficient Gene Disruption of Murine and Human Hematopoietic Progenitor Cells by CRISPR/Cas9

ATAC-seq Assay with Low Mitochondrial DNA Contamination from Primary Human CD4+ T Lymphocytes

Enhanced Yeast One-hybrid Screens To Identify Transcription Factor Binding To Human DNA Sequences

Multi-locus Variable-number Tandem-repeat Analysis of the Fish-pathogenic Bacterium Yersinia ruckeri by Multiplex PCR and Capillary Electrophoresis

Navigating MARRVEL, a Web-Based Tool that Integrates Human Genomics and Model Organism Genetics Information

In Vivo Functional Study of Disease-associated Rare Human Variants Using Drosophila