We thank Eric L Van Nostrand and Gene W Yeo for helpful guidance with the original protocol. K.Z. was supported by National Key R&#38;D Program of China (2016YFA0500902, 2018YFC1003500), and National Natural Science Foundation of China (31771653). L.Y. was supported by National Natural Science Foundation of China (81471502, 31871503) and Innovative and Entrepreneurial Program of Jiangsu Province.

All performed animal experiments have been approved by the Nanjing Medical University committee. Male C57BL/6 mice were kept under controlled photoperiod conditions and were supplied with food and water.
1. Tissue Harvesting and UV Crosslinking
<ol>
	<li>Euthanize 2 adult mice using carbon dioxide (CO2) for 1-2 min or until breathing stops. Next, perform cervical dislocation on each mouse.</li>
	<li>Harvest about 100 mg of testes from mice of appropriate age (one adult testis in t...

<ol>
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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Meiotic+sex+chromosome+inactivation.">Meiotic sex chromosome inactivation.</a> Development. 134 (10), 1823-1831 (2007).</li><li>Kimmins, S., Sassone-Corsi, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatin+remodelling+and+epigenetic+features+of+germ+cells.">Chromatin remodelling and epigenetic features of germ cells.</a> Nature. 434 (7033), 583-589 (2005).</li><li>Ule, 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=CLIP+identifies+Nova-regulated+RNA+networks+in+the+brain.">CLIP identifies Nova-regulated RNA networks in the brain.</a> Science. 302 (5648), 1212-1215 (2003).</li><li>Ule, J., Jensen, K., Mele, A., Darnell, R. 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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Argonaute+HITS-CLIP+decodes+microRNA-mRNA+interaction+maps.">Argonaute HITS-CLIP decodes microRNA-mRNA interaction maps.</a> Nature. 460 (7254), 479-486 (2009).</li><li>Zheng, K., 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=Mouse+MOV10L1+associates+with+Piwi+proteins+and+is+an+essential+component+of+the+Piwi-interacting+RNA+(piRNA)+pathway.">Mouse MOV10L1 associates with Piwi proteins and is an essential component of the Piwi-interacting RNA (piRNA) pathway.</a> Proceedings of National Acadamy of Sciences U S A. 107 (26), 11841-11846 (2010).</li><li>Gregersen, L. 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=MOV10+Is+a+5'+to+3'+RNA+helicase+contributing+to+UPF1+mRNA+target+degradation+by+translocation+along+3'+UTRs.">MOV10 Is a 5' to 3' RNA helicase contributing to UPF1 mRNA target degradation by translocation along 3' UTRs.</a> Molecular Cell. 54 (4), 573-585 (2014).</li><li>Banerjee, S., Neveu, P., Kosik, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+coordinated+local+translational+control+point+at+the+synapse+involving+relief+from+silencing+and+MOV10+degradation.">A coordinated local translational control point at the synapse involving relief from silencing and MOV10 degradation.</a> Neuron. 64 (6), 871-884 (2009).</li><li>Choi, J., Hwang, S. Y., Ahn, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interplay+between+RNASEH2+and+MOV10+controls+LINE-1+retrotransposition.">Interplay between RNASEH2 and MOV10 controls LINE-1 retrotransposition.</a> Nucleic Acids Research. 46 (4), 1912-1926 (2018).</li><li>Goodier, J. L., Cheung, L. E., Kazazian, H. 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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=MOV10+and+FMRP+regulate+AGO2+association+with+microRNA+recognition+elements.">MOV10 and FMRP regulate AGO2 association with microRNA recognition elements.</a> Cell Reports. 9 (5), 1729-1741 (2014).</li><li>Messaoudi-Aubert, S. 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=Role+for+the+MOV10+RNA+helicase+in+Polycomb-mediated+repression+of+the+INK4a+tumor+suppressor.">Role for the MOV10 RNA helicase in Polycomb-mediated repression of the INK4a tumor suppressor.</a> Nature Structural &amp; Molecular Biology. 17 (7), 862-868 (2010).</li><li>Sievers, C., Schlumpf, T., Sawarkar, R., Comoglio, F., Paro, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mixture+models+and+wavelet+transforms+reveal+high+confidence+RNA-protein+interaction+sites+in+MOV10+PAR-CLIP+data.">Mixture models and wavelet transforms reveal high confidence RNA-protein interaction sites in MOV10 PAR-CLIP data.</a> Nucleic Acids Research. 40 (20), e160 (2012).</li><li>Skariah, 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=Mov10+suppresses+retroelements+and+regulates+neuronal+development+and+function+in+the+developing+brain.">Mov10 suppresses retroelements and regulates neuronal development and function in the developing brain.</a> BMC Biology. 15 (1), 54 (2017).</li><li>Zheng, K., Wang, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blockade+of+pachytene+piRNA+biogenesis+reveals+a+novel+requirement+for+maintaining+post-meiotic+germline+genome+integrity.">Blockade of pachytene piRNA biogenesis reveals a novel requirement for maintaining post-meiotic germline genome integrity.</a> PLoS Genetics. 8 (11), e1003038 (2012).</li><li>Vourekas, 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=The+RNA+helicase+MOV10L1+binds+piRNA+precursors+to+initiate+piRNA+processing.">The RNA helicase MOV10L1 binds piRNA precursors to initiate piRNA processing.</a> Genes &amp; Development. 29 (6), 617-629 (2015).</li><li>Hocq, R., Paternina, J., Alasseur, Q., Genovesio, A., Le Hir, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitored+eCLIP:+high+accuracy+mapping+of+RNA-protein+interactions.">Monitored eCLIP: high accuracy mapping of RNA-protein interactions.</a> Nucleic Acids Research. 46 (21), 11553-11565 (2018).</li><li>Huppertz, I., 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=iCLIP:+protein-RNA+interactions+at+nucleotide+resolution.">iCLIP: protein-RNA interactions at nucleotide resolution.</a> Methods. 65 (3), 274-287 (2014).</li><li>Hafner, 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=Transcriptome-wide+identification+of+RNA-binding+protein+and+microRNA+target+sites+by+PAR-CLIP.">Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP.</a> Cell. 141 (1), 129-141 (2010).</li><li>Hafner, 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=PAR-CliP--a+method+to+identify+transcriptome-wide+the+binding+sites+of+RNA+binding+proteins.">PAR-CliP--a method to identify transcriptome-wide the binding sites of RNA binding proteins.</a> Journal of Visualized Experiments. 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A., Aktas, T., Backofen, R., Akhtar, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=uvCLAP+is+a+fast+and+non-radioactive+method+to+identify+in+vivo+targets+of+RNA-binding+proteins.">uvCLAP is a fast and non-radioactive method to identify in vivo targets of RNA-binding proteins.</a> Nature Communications. 9 (1), 1142 (2018).</li><li>Van Nostrand, E. 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=Robust+transcriptome-wide+discovery+of+RNA-binding+protein+binding+sites+with+enhanced+CLIP+(eCLIP).">Robust transcriptome-wide discovery of RNA-binding protein binding sites with enhanced CLIP (eCLIP).</a> Nature Methods. 13 (6), 508-514 (2016).</li><li>Radulovich, N., Leung, L., Tsao, M. 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With increasing understanding of the universal role of RBPs under both biological and pathological contexts, the CLIP methods have been widely utilized to reveal the molecular function of RBPs20,32,33,34,35. The protocol described here represents an adapted application of the eCLIP method to mouse testis.
One challenge in performing...

Mammalian testis represents an excellent developmental model wherein an intricate cell differentiation program runs cyclically to yield numerous spermatozoa. An unique value of this model lies in the emergence of transcriptional inactivation at certain stages of spermatogenesis, typically when meiotic sex chromosome inactivation (MSCI) occurs1,2 and when round spermatids undergo drastic nuclear compaction during spermiogenesis3. These inconsecutive transcriptional events necessitate post-transcriptional gene regulation, in which RNA-binding proteins (RBPs) play a crucial role, shaping transcriptome and maintaining male fertility.
To identify the bona fide RNA targets of an individual RBP in vivo, the crosslinking immunoprecipitation (CLIP) method was developed4,5, based on but beyond the regular RNA immunoprecipitation (RIP)6,7, by incorporation of key steps including ultraviolet (UV) crosslinking, stringent wash and gel transfer to improve signal specificity. The advanced application of the CLIP combined with high-throughput sequencing has provoked large interest in profiling protein-RNA interaction at genome-wide levels8. In addition to genetic studies on RBP function, such biochemical methods that identify the direct interplay of endogenous protein and RNA have been indispensable to accurately elucidate the RNA regulatory roles of RBPs. For example, MOV10L1 is a testis-specific RNA helicase required for male fertility and the Piwi-interacting RNA (piRNA) biogenesis9. Its paralogue MOV10 is known as a ubiquitously expressed and multifunctional RNA helicase with roles in multiple aspects of RNA biology10,11,12,13,14,15,16,17,18. By employing the conventional CLIP-seq, we found that MOV10L1 binds and regulates primary piRNA precursors to initiate early piRNA processing19,20, and that MOV10 binds mRNA 3&#39; UTRs and as well as noncoding RNA species in testicular germ cells (data not shown).
Nevertheless, CLIP is originally a laborious, radioactive procedure followed by sequencing library preparation with a remarkable loss of CLIP tags. In the conventional CLIP, a cDNA library is prepared using adapters ligated at both RNA extremities. After protein digestion, crosslinked short polypeptides remain attached to RNA fragments. This crosslinking mark partially blocks reverse transcriptase (RTase) progression during cDNA synthesis, resulting in truncated cDNAs which represent about 80% of the cDNA library21,22. Thus, only cDNA fragments resulting from RTase bypassing the crosslinking site (read-through) are sequenced. Recently, various CLIP approaches, such as PAR-CLIP, iCLIP, eCLIP and uvCLAP, have been employed to identify crosslink sites of RBPs in living cells. PAR-CLIP involves the application of 365 nm UV radiation and photoactivatable nucleotide analogs and is therefore exclusive to in-culturing living cells, and incorporation of nucleoside analogs into newly synthesized transcripts is prone to producing bias where RNA physically interacts with protein23,24. In iCLIP, only a single adapter is ligated to the 3&#39; extremity of crosslinked RNA fragments. After reverse transcription (RT), both truncated and read-through cDNAs are obtained by intramolecularly circularization and re-linearization followed by polymerase chain reaction (PCR) amplification25,26. However, the efficiency of intramolecular circularization is relatively low. Although older CLIP protocols need labeling of crosslinked RNA with a radioisotope, ultraviolet crosslinking and affinity purification (uvCLAP), with a process of stringent tandem affinity purification, does not rely on radioactivity27. Nevertheless, uvCLAP is limited to cultured cells that must be transfected with the expression vector carrying the 3x FLAG-HBH tag for tandem affinity purification.
In eCLIP, adapters were ligated first at the 3&#39; extremity of RNA followed by RT, and next at the 3&#39; extremity of cDNAs in an intermolecular mode. Hence, eCLIP is able to capture all truncated and read-through cDNA28. Also, it is neither restricted to radioactive labeling, nor to using cell lines based on its principle, while maintaining single-nucleotide resolution.
Here, we provide a step-by-step description of an eCLIP protocol adapted for mouse testis. Briefly, this eCLIP protocol starts with UV crosslinking of testicular tubules, followed by partial RNase digestion and immunoprecipitation using a protein-specific antibody. Next, the protein-bound RNA is dephosphorylated, and adapter is ligated to its 3&#39; end.&#160;After protein gel electrophoresis and gel-to-membrane transfer, RNA is isolated by cutting the membrane area of an expected size range. After RT, DNA adapter is ligated to the 3&#39; end of cDNA followed by PCR amplification. Screening of subclones prior to high-throughput sequencing is taken as a library quality control. This protocol is efficient at identifying major species of protein-bound RNA of RBPs, exemplified by the two testis-expressing RNA helicases MOV10L1 and MOV10.

<table border="0" cellpadding="0" cellspacing="0" style="width:804px;" width="804">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Antibodies</td>
			<td style="width:180px;"></td>
			<td style="width:171px;"></td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:229px;">Anti-mouse MOV10&#160; antibody</td>
			<td style="width:180px;">Proteintech, China</td>
			<td style="width:171px;">10370-1-AP</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="48">
			<td height="48" style="height:48px;width:229px;">Anti-mouse MOV10L1 antibody</td>
			<td style="width:180px;">Zheng et al.20109</td>
			<td style="width:171px;">polyclonal antisera UP2175</td>
			<td style="width:224px;">provided by P. Jeremy Wang lab&#65288;University of Pennsylvania&#65289;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">HRP Goat Anti-Rabbit IgG&#160;</td>
			<td style="width:180px;">ABclonal</td>
			<td style="width:171px;">AS014</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Rabbit IgG</td>
			<td style="width:180px;">Beyotime, China</td>
			<td style="width:171px;">A7016</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Equipment</td>
			<td style="width:180px;"></td>
			<td style="width:171px;"></td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">Centrifuge</td>
			<td style="width:180px;">Eppendorf, Hamburg, Germany</td>
			<td style="width:171px;">5242R</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Digital sonifier</td>
			<td style="width:180px;">BRANSON,USA</td>
			<td style="width:171px;">BBV12081048A</td>
			<td style="width:224px;">450 Watts; 50/60 HZ</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">DynaMag-2 Magnet</td>
			<td style="width:180px;">Invitrogen,USA</td>
			<td style="width:171px;">12321D</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Mini Blot Module</td>
			<td style="width:180px;">Invitrogen,USA</td>
			<td style="width:171px;">B1000</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Mini Gel Tank</td>
			<td style="width:180px;">Invitrogen,USA</td>
			<td style="width:171px;">A25977</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Shaking incubator</td>
			<td>Eppendorf, Hamburg, Germany</td>
			<td>Thermomixer comfort&#160;</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="38">
			<td height="38" style="height:39px;">Tissue Grinder, Dounce</td>
			<td>PYREX, USA</td>
			<td>1234F35</td>
			<td style="width:224px;">only&#160; the &#34;loose&#34; pestle is used in this protocol</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">TProfessional standard 96 Gradient</td>
			<td style="width:180px;">Biometra, Germany</td>
			<td style="width:171px;">serial no.: 2604323</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Tube Revolver&#160;</td>
			<td style="width:180px;">Crystal, USA</td>
			<td style="width:171px;">serial no.: 3406051</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">UV-light cross-linker</td>
			<td>UVP, USA</td>
			<td style="width:171px;">CL-1000</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Materials</td>
			<td></td>
			<td style="width:171px;"></td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">TC-treated Culture Dish</td>
			<td>Corning, USA</td>
			<td style="width:171px;">430167</td>
			<td style="width:224px;">100 mm&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Tubes</td>
			<td style="width:180px;">Corning, USA</td>
			<td style="width:171px;">430791</td>
			<td style="width:224px;">15 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Microtubes tubes</td>
			<td style="width:180px;">AXYGEN , USA</td>
			<td style="width:171px;">MCT-150-C</td>
			<td style="width:224px;">1.5 mL&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Reagents&#160;</td>
			<td style="width:180px;"></td>
			<td style="width:171px;"></td>
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		<tr height="62">
			<td height="62" style="height:62px;width:229px;">Acid phenol/chloroform/isoamyl alcohol&#160;</td>
			<td style="width:180px;">Solarbio, China</td>
			<td style="width:171px;">P1011</td>
			<td style="width:224px;">25:24:01</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">AffinityScript Enzyme</td>
			<td style="width:180px;">Agilent, USA</td>
			<td style="width:171px;">600107</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Antioxidant</td>
			<td style="width:180px;">Invitrogen,USA</td>
			<td style="width:171px;">NP0005</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="65">
			<td height="65" style="height:65px;width:229px;">DH5&#945; competent bacteria</td>
			<td style="width:180px;">Thermo Scientific, USA</td>
			<td>18265017</td>
			<td style="width:224px;">these economical cells yield &#62;1 x 106 transformants/&#181;g control DNA per 50 &#181;L reaction.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">DMSO</td>
			<td style="width:180px;">Sigma-Aldrich, USA</td>
			<td style="width:171px;">D8418</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">DNA Ladder</td>
			<td style="width:180px;">Invitrogen, USA</td>
			<td style="width:171px;">10416014</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">dNTP</td>
			<td style="width:180px;">Sigma-Aldrich, USA</td>
			<td style="width:171px;">DNTP100-1KT</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dynabeads Protein A&#160;</td>
			<td>Invitrogen, USA</td>
			<td>10002D</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ECL reagent</td>
			<td>Vazyme, China</td>
			<td>E411-04</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">EDTA</td>
			<td>Invitrogen, USA</td>
			<td style="width:171px;">AM9260G</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">EDTA free protease inhibitor cocktail</td>
			<td style="width:180px;">Roche, USA</td>
			<td style="width:171px;">04693132001</td>
			<td style="width:224px;">add fresh</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Exo-SAP-IT</td>
			<td style="width:180px;">Affymetrix, USA</td>
			<td style="width:171px;">78201</td>
			<td style="width:224px;">PCR Product Cleanup Reagent&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">FastAP enzyme</td>
			<td style="width:180px;">Thermo Scientific, USA</td>
			<td style="width:171px;">EF0652</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">LDS Sample Buffer</td>
			<td style="width:180px;">Thermo Scientific, USA</td>
			<td style="width:171px;">NP0007</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">MetaPhor Agarose&#160;</td>
			<td style="width:180px;">lonza, Switzerland</td>
			<td style="width:171px;">50180</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:229px;">MgCl2</td>
			<td>Invitrogen, USA</td>
			<td style="width:171px;">AM9530G</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="66">
			<td height="66" style="height:66px;width:229px;">MiniElute gel Extraction</td>
			<td style="width:180px;">QIAGEN, Germany</td>
			<td style="width:171px;">28604</td>
			<td style="width:224px;">column store at 4 &#8451;; buffer QG=gel dissolving buffer; buffer PE= wash buffer(for step 14)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">MyONE Silane beads</td>
			<td style="width:180px;">Thermo Scientific, USA</td>
			<td>37002D</td>
			<td style="width:224px;">nucleic acids extraction magnetic beads</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaCl</td>
			<td>Invitrogen,USA</td>
			<td>AM9759 
			&#160;</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">NP-40</td>
			<td style="width:180px;">Amresco, USA</td>
			<td style="width:171px;">M158-500ML</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">NuPAGE Bis-Tris Protein Gels</td>
			<td style="width:180px;">Invitrogen, USA</td>
			<td style="width:171px;">NP0336BOX</td>
			<td style="width:224px;">4%&#8211;12%,1.5 mm, 15-well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">NuPAGE MOPS SDS Buffer Kit&#160;</td>
			<td style="width:180px;">Invitrogen, USA</td>
			<td style="width:171px;">NP0050</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PBS</td>
			<td>Gibco, USA</td>
			<td>10010023</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">Phase-Locked Gel (PLG) heavy tube&#160;&#160;</td>
			<td style="width:180px;">TIANGEN, China</td>
			<td style="width:171px;">WM5-2302831</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">PowerUp SYBR Green Master Mix</td>
			<td style="width:180px;">Applied Biosystems, USA</td>
			<td style="width:171px;">A25742</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">proteinase K</td>
			<td style="width:180px;">NEB, New England&#160;</td>
			<td style="width:171px;">P8107S</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Q5 PCR master mix&#160;</td>
			<td style="width:180px;">NEB, New England&#160;</td>
			<td style="width:171px;">M0492L</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">RLT buffer</td>
			<td style="width:180px;">QIAGEN, Germany</td>
			<td style="width:171px;">79216</td>
			<td style="width:224px;">RNA purification lysis buffer&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:229px;">RNA Clean &#38; Concentrator-5 columns&#160;</td>
			<td style="width:180px;">ZYMO RESEARCH, USA</td>
			<td style="width:171px;">R1016</td>
			<td style="width:224px;">RNA purification and concentration columns</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">RNase I&#160;</td>
			<td>Invitrogen, USA</td>
			<td style="width:171px;">AM2295</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">RNase Inhibitor</td>
			<td style="width:180px;">Promega, USA</td>
			<td style="width:171px;">N251B</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">RQ1 DNase</td>
			<td style="width:180px;">Promega,USA</td>
			<td style="width:171px;">M610A</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Sample Reducing Agent</td>
			<td>Invitrogen,USA</td>
			<td style="width:171px;">NP0009</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">SDS Solution</td>
			<td>Invitrogen, USA</td>
			<td style="width:171px;">15553027</td>
			<td style="width:224px;">10%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Sodium deoxycholate</td>
			<td style="width:180px;">Sigma-Aldrich, USA</td>
			<td style="width:171px;">30970</td>
			<td style="width:224px;">protect from light</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">T4 PNK enzyme</td>
			<td style="width:180px;">NEB, New England&#160;</td>
			<td style="width:171px;">M0201L</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">T4 RNA ligase 1 high conc</td>
			<td style="width:180px;">NEB, New England&#160;</td>
			<td style="width:171px;">M0437M</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">TA/Blunt-Zero Cloning Mix</td>
			<td style="width:180px;">Vazyme, China</td>
			<td style="width:171px;">C601-01</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">TBE</td>
			<td>Invitrogen,USA</td>
			<td style="width:171px;">AM9863</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tris-HCI Buffer</td>
			<td>Invitrogen, USA</td>
			<td>15567027</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Triton X-100</td>
			<td style="width:180px;">Sangon Biotech, China</td>
			<td style="width:171px;">A600198&#160;</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Tween-20</td>
			<td style="width:180px;">Sangon Biotech, China</td>
			<td style="width:171px;">A600560</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">Urea</td>
			<td style="width:180px;">Sigma-Aldrich, USA</td>
			<td style="width:171px;">U5378</td>
			<td style="width:224px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:229px;">X-ray Films</td>
			<td style="width:180px;">Caresteam, Canada</td>
			<td style="width:171px;">6535876</td>
			<td style="width:224px;"></td>
		</tr>
	</tbody>
</table>

enhanced crosslinking immunoprecipitation (eclip) method for efficient identification of protein-bound rna in mouse testis

Spermatogenesis defines a highly ordered process of male germ cell differentiation in mammals. In testis, transcription and translation are uncoupled, underlining the importance of post-transcriptional regulation of gene expression orchestrated by RBPs. To elucidate mechanistic roles of an RBP, crosslinking immunoprecipitation (CLIP) methodology can be used to capture its endogenous direct RNA targets and define the actual interaction sites. The enhanced CLIP (eCLIP) is a newly-developed method that offers several advantages over the conventional CLIPs. However, the use of eCLIP has so far been limited to cell lines, calling for expanded applications. Here, we employed eCLIP to study MOV10 and MOV10L1, two known RNA-binding helicases, in mouse testis. As expected, we find that MOV10 predominantly binds to 3' untranslated regions (UTRs) of mRNA and MOV10L1 selectively binds to Piwi-interacting RNA (piRNA) precursor transcripts. Our eCLIP method allows fast determination of major RNA species bound by various RBPs via small-scale sequencing of subclones and thus availability of qualified libraries, as a warrant for proceeding with deep sequencing. This study establishes an applicable basis for eCLIP in mammalian testis.

The eCLIP procedure and results are illustrated in Figure 1, Figure 2, Figure 3, Figure 4. Mice were euthanized with carbon dioxide and a small incision was made in the lower abdomen using surgical scissors (Figure 2A,B). Mo...

Watch this Scientific Journal Video about Enhanced Crosslinking Immunoprecipitation eCLIP Method for Efficient Identification of Protein-bound RNA in Mouse Testis at JoVE.com

Enhanced Crosslinking Immunoprecipitation eCLIP Method for Efficient Identification of Protein-bound RNA in Mouse Testis

Here, we present an eCLIP protocol to determine major RNA targets of RBP candidates in testis.

Enhanced Crosslinking Immunoprecipitation (eCLIP) Method for Efficient Identification of Protein-bound RNA in Mouse Testis

Spermatogenesis defines a highly ordered process of male germ cell differentiation in mammals. In testis, transcription and translation are uncoupled, ...

RNA-binding proteins are essential to cellular physiology. Importantly, the RBP are highly expressed throughout spermatogenesis and have been well-documented as essential post-transcriptional regulators during all stages of germ cells. Identification of binding targets is critical to elucidate the mechanistic roles of RBP.This protocol represents an adapted application of eCLIP method to capture endogenous direct RNA targets and establishes an applicable basis for eCLIP in mammalian testis. The main advantage of this method is that it is non-radioactive, less time-intensive, and provides a stronger signal-to-noise ratio because the size-matched input will serve as an appropriate background for authentic targets. Lastly, we think that small-scale sequencing of subclones are useful to following deep sequencing.Demonstrating the procedure will be Xu Qiushi, my colleague. To begin this procedure, harvest about 100 milligrams of testes from mice of appropriate age for each immunoprecipitation experiment. Place the tissues in ice-cold PBS.Using a pair of fine-tipped tweezers, gently remove the tunica albuginea. Add three milliliters of ice-cold PBS to a tissue grinder, and use a loose glass pestle to triturate the tissue by mild mechanical force. Next, transfer the tissue suspension to a cell culture dish, and add ice-cold PBS up to six milliliters.Shake the plate quickly so that liquid covers the bottom of the dish evenly. Crosslink the suspension on ice three times with 400 millijoules per centimeter squared at 254 nanometers. Make sure to mix the suspension between each irradiation.Then, collect the suspension in a 15-milliliter conical tube, and centrifuge at 1, 200 times g and at four degrees for five minutes. Remove the supernatant, and resuspend the pellet in one milliliter of PBS. After this, transfer the suspension to a 1.5-milliliter centrifuge tube.Centrifuge at 1, 000 times g and at four degrees Celsius for two minutes, and discard the supernatant. First, add 125 microliters of protein A magnetic beads per sample to a fresh centrifuge tube. Place the tube on the magnet to separate the beads from the solution.After 10 seconds, remove the supernatant, and wash the beads twice with one milliliter of ice-cold lysis buffer. Resuspend the beads in 100 microliters of cold lysis buffer with 10 micrograms of eCLIP antibody. Rotate the tubes at room temperature for 45 minutes.Then, wash the beads twice with one milliliter of ice-cold lysis buffer. To begin, resuspend the tissue pellets in one milliliter of cold lysis buffer containing 22 microliters of 50x EDTA-free protein inhibitor cocktail and 11 microliters of RNase inhibitor. Keep lysing the samples on ice for 15 minutes.Sonicate each sample as outlined in the text protocol. Next, add four microliters of DNase to each tube and mix well. Incubate at 37 degrees Celsius for 10 minutes while shaking at 1, 200 rpm.After this, add 10 microliters of diluted RNase and mix well. Incubate at 37 degrees Celsius for five minutes while shaking at 1, 200 rpm. Then, centrifuge at 15, 000 times g and at four degrees Celsius for 20 minutes to clear the lysate.Carefully collect the supernatant, and save input samples for RWB and RRI samples. First, add one milliliter of the lysate to the prepared beads, and rotate the samples at four degrees Celsius for either two hours or overnight. After this, collect the beads with a magnetic stand, and discard the supernatant.Wash the beads twice with 900 microliters of high-salt buffer, and then wash the beads twice with 900 microliters of wash buffer. Then, wash the beads once with 500 microliters of 1x dephosphorylation buffer. First, discard the supernatant, and use fine pipette tips to remove any residual liquid.Add 25 microliters of three-prime ligation master mix to each sample, and carefully pipette to mix. Add 2.5 microliters of RNA adapter X1A and 2.5 microliters of RNA adapter X1B to each sample. Mix carefully by pipetting or flicking.Incubate at 25 degrees Celsius for 75 minutes, making sure to flick the tube to mix every 10 minutes. Wash the beads once with 500 microliters of cold wash buffer. Next, wash the beads once with 500 microliters of cold high-salt buffer and then with 500 microliters of cold wash buffer.Repeat both of these washes once more. Magnetically separate the beads, and use fine pipette tips to remove any residual liquid. Resuspend the beads in 100 microliters of cold wash buffer, and move 20 microliters to new tubes as RWB samples.Add 7.5 microliters of 4x LDS sample buffer and three microliters of 10x sample reducing agent to the remaining samples. Incubate at 70 degrees Celsius for 10 minutes while shaking at 1, 200 rpm. After this, cool the samples on ice for one minute, and centrifuge at 1, 000 times g and at four degrees Celsius for one minute.For RWB gel, place tubes on a magnet, and separate protein eluate from the beads. Load 15 microliters of sample into each well. Next, add 500 microliters of antioxidant to 500 milliliters of 1x SDS running buffer.Run the gel at 200 volts, 1x SDS running buffer for 50 minutes or until the dye front is at the bottom. Transfer the protein-RNA complexes from the gel to a nitrocellulose membrane at 10 volts for 70 minutes in 1x transfer buffer with 10%methanol. Block the RWB membrane in 5%milk in TBST at room temperature for one hour.Rinse the membrane in TBST, and incubate with primary antibody in TBST overnight at four degrees Celsius. After this, wash twice with TBST, with each wash lasting five minutes. Incubate with secondary antibody in TBST at room temperature for one hour.Then, wash the membrane three times with TBST. Next, mix equal volumes of ECL buffer A and buffer B.Add this mixture to the membrane, and incubate for one minute. Cover the membrane with plastic wrap, and expose it to an x-ray film at room temperature for two to three minutes before developing the film.In this study, MOV10 eCLIP in testes from adult wild-type mice with RNase I treating the crosslinked lysate, the target protein, which is approximately 114 kilodaltons, is successfully enriched. The qPCR results of cDNA diluted one to 10 from various samples reveals that non-crosslinked samples show decreased RNA recovery. It is observed that the Ct values of the non-crosslinked group is generally five times more than UV-crosslinked group.Representative results for PCR amplification and size selection via agarose gel electrophoresis are shown here. The primer-dimer product appears at about 140 base pairs. The UCSC Genome Browser view of two representative subclone sequences shows that MOV10-bound eCLIP tags are found to be located within the three-prime UTR of gene Fto.The approximate rate of three-prime UTR targets accounts for 75%is consistent with the majority of MOV10 targets in HEK293 cells and in testes. In contrast, MOV10L1-bound eCLIP tags are found to be located within a piRNA cluster, indicating MOV10L1 targets piRNA precursors. The approximate rate of piRNA precursor targets accounts for 42%which reflect a trend from previous studies.MOV10L1 eCLIP with a 40-unit-per-milliliter RNase I digestion yields relatively more sequences with less than 20 base pairs. This protocol described here represents an employment of the eCLIP method in reproduction, an area in which the RNA-RBP interaction knowledge is rather insufficient.

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Biology

19.5K visualizações.  Nanjing Medical University. Proteínas de ligação de RNA são essenciais para a fisiologia celular. É importante ressaltar que o RBP é altamente expresso ao longo da espermatogênese e tem sido bem documentado como reguladores pós-transcrição essenciais durante todas as fases das células germinativas. A identificação de alvos vinculantes é fundamental para elucidar os papéis mecanicistas do RBP.Este protocolo representa uma aplicação adaptada do método eCLIP para capturar alvos rna diretos endógen...