Name: efficient transcriptionally controlled plasmid expression system for investigation of the stability of mrna transcripts in primary alveolar epithelial cells
Uploaded: 2020-03-06T12:30:00
Description: Watch this Scientific Journal Video about Efficient Transcriptionally Controlled Plasmid Expression System for Investigation of the Stability of mRNA Transcripts in Primary Alveolar Epithelial Cells a

Francis Migneault was supported by a fellowship provided by the Quebec Respiratory Health Network and the Canadian Institutes of Health Research (CIHR) lung training program, a studentship from FRSQ and a studentship from the Facult&#233; des &#201;tudes Sup&#233;rieures et Postdoctorales, Universit&#233; de Montr&#233;al. This work was supported by the Gosselin-Lamarre Chair in clinical research and the Canadian Institutes of Health Research [YBMOP-79544].

All animal procedures were conducted according to the guidelines of the Canadian Council on Animal Care and were approved by the Institutional Animal Care Committee of the Research Center of Centre Hospitalier de l&#39;Universit&#233; de Montr&#233;al (CRCHUM).
1. Design and generation of the response plasmid expressing the gene of interest (GOI)
<ol>
	<li>Use an inducible tetracycline-off vector, such as pTRE-Tight.</li>
	<li>Analyze the sequence of the GOI and the multiple cloning site (MC...

<ol>
	<li>Munchel, S. E., Shultzaberger, R. K., Takizawa, N., Weis, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+profiling+of+mRNA+turnover+reveals+gene-specific+and+system-wide+regulation+of+mRNA+decay.">Dynamic profiling of mRNA turnover reveals gene-specific and system-wide regulation of mRNA decay.</a> Molecular Biology of the Cell. 22 (15), 2787-2795 (2011).</li><li>Ljungman, 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+transcription+stress+response.">The transcription stress response.</a> Cell Cycle. 6 (18), 2252-2257 (2007).</li><li>Ross, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=mRNA+stability+in+mammalian+cells.">mRNA stability in mammalian cells.</a> Microbiological Reviews. 59 (3), 423-450 (1995).</li><li>Gossen, M., Bujard, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tight+control+of+gene+expression+in+mammalian+cells+by+tetracycline-responsive+promoters.">Tight control of gene expression in mammalian cells by tetracycline-responsive promoters.</a> Proceedings of the National Academy of Sciences. 89 (12), 5547-5551 (1992).</li><li>Meyer, D. J., Stephenson, E. W., Johnson, L., Cochran, B. H., Schwartz, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+serum+response+element+can+mediate+induction+of+c-fos+by+growth+hormone.">The serum response element can mediate induction of c-fos by growth hormone.</a> Proceedings of the National Academy of Sciences. 90 (14), 6721-6725 (1993).</li><li>Harkin, D. 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=Induction+of+GADD45+and+JNK/SAPK-dependent+apoptosis+following+inducible+expression+of+BRCA1.">Induction of GADD45 and JNK/SAPK-dependent apoptosis following inducible expression of BRCA1.</a> Cell. 97 (5), 575-586 (1999).</li><li>Formisano, 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=The+two+isoforms+of+the+Na+/Ca2++exchanger,+NCX1+and+NCX3,+constitute+novel+additional+targets+for+the+prosurvival+action+of+Akt/protein+kinase+B+pathway.">The two isoforms of the Na+/Ca2+ exchanger, NCX1 and NCX3, constitute novel additional targets for the prosurvival action of Akt/protein kinase B pathway.</a> Molecular Pharmacology. 73 (3), 727-737 (2008).</li><li>Yin, D. X., Schimke, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BCL-2+expression+delays+drug-induced+apoptosis+but+does+not+increase+clonogenic+survival+after+drug+treatment+in+HeLa+cells.">BCL-2 expression delays drug-induced apoptosis but does not increase clonogenic survival after drug treatment in HeLa cells.</a> Cancer Research. 55 (21), 4922-4928 (1995).</li><li>Johnstone, R. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+analysis+of+the+leukemia+protein+ELL:+evidence+for+a+role+in+the+regulation+of+cell+growth+and+survival.">Functional analysis of the leukemia protein ELL: evidence for a role in the regulation of cell growth and survival.</a> Molecular and Cellular Biology. 21 (5), 1672-1681 (2001).</li><li>Olotu, C., 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=Streptococcus+pneumoniae+inhibits+purinergic+signaling+and+promotes+purinergic+receptor+P2Y2+internalization+in+alveolar+epithelial+cells.">Streptococcus pneumoniae inhibits purinergic signaling and promotes purinergic receptor P2Y2 internalization in alveolar epithelial cells.</a> Journal of Biological Chemistry. 294 (34), 12795-12806 (2019).</li><li>Goldmann, T., 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=Human+alveolar+epithelial+cells+type+II+are+capable+of+TGFbeta-dependent+epithelial-mesenchymal-transition+and+collagen-synthesis.">Human alveolar epithelial cells type II are capable of TGFbeta-dependent epithelial-mesenchymal-transition and collagen-synthesis.</a> Respiratory Research. 19 (1), 138 (2018).</li><li>Huang, C., 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=Ghrelin+ameliorates+the+human+alveolar+epithelial+A549+cell+apoptosis+induced+by+lipopolysaccharide.">Ghrelin ameliorates the human alveolar epithelial A549 cell apoptosis induced by lipopolysaccharide.</a> Biochemical and Biophysical Research Communications. 474 (1), 83-90 (2016).</li><li>Gao, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emodin+suppresses+TGF-beta1-induced+epithelial-mesenchymal+transition+in+alveolar+epithelial+cells+through+Notch+signaling+pathway.">Emodin suppresses TGF-beta1-induced epithelial-mesenchymal transition in alveolar epithelial cells through Notch signaling pathway.</a> Toxicology and Applied Pharmacology. 318, 1-7 (2017).</li><li>Cooper, J. 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=Long+Term+Culture+of+the+A549+Cancer+Cell+Line+Promotes+Multilamellar+Body+Formation+and+Differentiation+towards+an+Alveolar+Type+II+Pneumocyte+Phenotype.">Long Term Culture of the A549 Cancer Cell Line Promotes Multilamellar Body Formation and Differentiation towards an Alveolar Type II Pneumocyte Phenotype.</a> PLoS One. 11 (10), e0164438 (2016).</li><li>Hirakata, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monolayer+culture+systems+with+respiratory+epithelial+cells+for+evaluation+of+bacterial+invasiveness.">Monolayer culture systems with respiratory epithelial cells for evaluation of bacterial invasiveness.</a> Tohoku Journal of Experimental Medicine. 220 (1), 15-19 (2010).</li><li>Grzybowska, E. A., Wilczynska, A., Siedlecki, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulatory+functions+of+3'UTRs.">Regulatory functions of 3'UTRs.</a> Biochemical and Biophysical Research Communications. 288 (2), 291-295 (2001).</li><li>Chen, C. Y., Chen, S. T., Juan, H. F., Huang, H. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lengthening+of+3'UTR+increases+with+morphological+complexity+in+animal+evolution.">Lengthening of 3'UTR increases with morphological complexity in animal evolution.</a> Bioinformatics. 28 (24), 3178-3181 (2012).</li><li>Eaton, D. C., Helms, M. N., Koval, M., Bao, H. F., Jain, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+contribution+of+epithelial+sodium+channels+to+alveolar+function+in+health+and+disease.">The contribution of epithelial sodium channels to alveolar function in health and disease.</a> Annual Review of Physiology. 71, 403-423 (2009).</li><li>Boncoeur, 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=Modulation+of+epithelial+sodium+channel+activity+by+lipopolysaccharide+in+alveolar+type+II+cells:+involvement+of+purinergic+signaling.">Modulation of epithelial sodium channel activity by lipopolysaccharide in alveolar type II cells: involvement of purinergic signaling.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 298 (3), L417-L426 (2010).</li><li>Gonzalez, R. F., Dobbs, L. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+culture+of+alveolar+epithelial+Type+I+and+Type+II+cells+from+rat+lungs.">Isolation and culture of alveolar epithelial Type I and Type II cells from rat lungs.</a> Methods in Molecular Biology. 945, 145-159 (2013).</li><li>Kozak, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=At+least+six+nucleotides+preceding+the+AUG+initiator+codon+enhance+translation+in+mammalian+cells.">At least six nucleotides preceding the AUG initiator codon enhance translation in mammalian cells.</a> Journal of Molecular Biology. 196 (4), 947-950 (1987).</li><li>Ke, S. H., Madison, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+and+efficient+site-directed+mutagenesis+by+single-tube+'megaprimer'+PCR+method.">Rapid and efficient site-directed mutagenesis by single-tube 'megaprimer' PCR method.</a> Nucleic Acids Research. 25 (16), 3371-3372 (1997).</li><li>Gossen, M., Bujard, H., Nelson, M., Hillen, W., Greenwald, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Tetracyclines in Biology, Chemistry and Medicine. , (2001).</li><li>Migneault, 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=Post-Transcriptional+Modulation+of+aENaC+mRNA+in+Alveolar+Epithelial+Cells:+Involvement+of+its+3'+Untranslated+Region.">Post-Transcriptional Modulation of aENaC mRNA in Alveolar Epithelial Cells: Involvement of its 3' Untranslated Region.</a> Cellular Physiology and Biochemistry. 52 (5), 984-1002 (2019).</li><li>Migneault, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Modulation de la stabilit&#233; de l'ARNm alphaENaC dans les cellules &#233;pith&#233;liales alv&#233;olaires: d&#233;termination du r&#244;le des s&#233;quences 3' non traduites. , (2015).</li><li>Grzesik, B. 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=Efficient+gene+delivery+to+primary+alveolar+epithelial+cells+by+nucleofection.">Efficient gene delivery to primary alveolar epithelial cells by nucleofection.</a> American Journal of Physiology-Lung Cellular and Molecular Physiology. 305 (11), L786-L794 (2013).</li><li>Sourdeval, M., Lemaire, C., Brenner, C., Boisvieux-Ulrich, E., Marano, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+doxycycline-induced+cytotoxicity+on+human+bronchial+epithelial+cells.">Mechanisms of doxycycline-induced cytotoxicity on human bronchial epithelial cells.</a> Frontiers in Bioscience. 11, 3036-3048 (2006).</li><li>Moon, A., Gil, S., Gill, S. E., Chen, P., Matute-Bello, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Doxycycline+impairs+neutrophil+migration+to+the+airspaces+of+the+lung+in+mice+exposed+to+intratracheal+lipopolysaccharide.">Doxycycline impairs neutrophil migration to the airspaces of the lung in mice exposed to intratracheal lipopolysaccharide.</a> Journal of Inflammation-London. 9 (1), 31 (2012).</li><li>Hovel, H., Frieling, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+doxycycline,+mezlocillin+and+clotrimazole+in+cell+culture+media+as+contamination+prophylaxis.">The use of doxycycline, mezlocillin and clotrimazole in cell culture media as contamination prophylaxis.</a> Developments in Biological Standardization. 66, 23-28 (1987).</li><li>Houseley, J., Tollervey, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+many+pathways+of+RNA+degradation.">The many pathways of RNA degradation.</a> Cell. 136 (4), 763-776 (2009).</li><li>Tani, 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=Genome-wide+determination+of+RNA+stability+reveals+hundreds+of+short-lived+noncoding+transcripts+in+mammals.">Genome-wide determination of RNA stability reveals hundreds of short-lived noncoding transcripts in mammals.</a> Genome Research. 22 (5), 947-956 (2012).</li></ol>

The low transfection rate of alveolar epithelial cells in primary culture has been a serious limitation for the use of the Tet-Off system to assess mRNA stability in these cells. However, this limitation was overcome by pipette electroporation, allowing a 25-30% transfection efficiency (Figure 1 and Figure 3)26.
The measurement of transcript stability is fundamental to understanding the modulation of a given mR...

Several techniques have been developed to determine the half-life of mRNAs. The pulse-chase decay technique, which utilizes labeled mRNAs, allows for the simultaneous evaluation of a large pool of mRNAs with minimal cellular disturbance. However, this approach does not allow a direct estimation of the half-life of a single gene transcript and cannot be implemented to study the posttranscriptional modulation of an mRNA following stimulation with growth factors, ROS, alarmins, or inflammation1.
The use of transcription inhibitors, such as actinomycin D and &#945;-amanitin, is a relatively simple method for measuring mRNA degradation kinetics over time. One main advantage of this approach over that of previous techniques, (i.e., pulse-chase) relies on the ability to directly estimate the half-life of a given transcript and compare how different treatments could affect its degradation kinetics. However, the significant deleterious impact of transcription inhibitors on cell physiology represents a major drawback of the approach2. Indeed, the inhibition of the whole cell transcriptome with these drugs has the negative side effect of perturbing the synthesis of key elements involved in mRNA stability, such as microRNAs (miRNAs), as well as the expression and synthesis of RNA-binding proteins, which are important for mRNA degradation and stability. The severe perturbation of gene transcription by these drugs could therefore artefactually modify the degradation curves of transcripts.
The promoter induction system represents a third approach to measure the half-life of a specific mRNA. This method measures the degradation of a specific mRNA in a similar way as methods that use transcription inhibitors. Two types of induction systems are frequently used: the serum-induced c-fos promoter3 and the Tet-Off inducible system4. With the c-fos system, the use of transcription inhibitors that can be toxic to the cell is not needed. However, this method requires cell cycle synchronization, which prevents the evaluation of the actual stability of a transcript during interphase5. In contrast, the Tet-Off system allows the strong expression of the gene of interest (GOI) under the control of a synthetic tetracycline-regulated promoter. This system requires the presence of two elements that must be cotransfected into the cell to be functional. The first plasmid (pTet-Off) expresses the regulatory protein tTA-Adv, a hybrid synthetic transcription factor composed of the prokaryotic repressor TetR (from Escherichia coli) fused to three transcription transactivation domains from the viral protein HSV VP16. The GOI is cloned into the pTRE-Tight plasmid under the control of a synthetic promoter (PTight), comprising the minimal sequence of the cytomegalovirus (CMV) promoter fused to seven repeats of the tetO operator sequence. The transcription of the gene downstream of PTight is dependent on the interaction of TetR with tetO. In the presence of tetracycline or its derivative, doxycycline, the TetR repressor loses its affinity for the tetO operator, leading to a cessation of transcription4. The characteristics of the Tet-Off system make it an ideal model for the study of specific mRNA expression in eukaryotic cells while avoiding potential pleiotropic effects that are secondary to the absence of prokaryotic regulatory sequences in eukaryotic cell6. Usually, doubly stable Tet-Off cell lines (HEK 293, HeLa, and PC12) are used with this system to integrate copies of the regulator and response plasmids for convenient access to controllable gene expression7,8,9.
Several models of alveolar epithelial cells in culture have been used to study the cellular and molecular biology of the alveolar epithelium. For years, researchers have extensively utilized human or rodent primary cells10,11 as well as immortalized cell lines such as human A549 or rat RLE-6TN cells12,13. Although they are generally less proliferative and more difficult to culture and to transfect, alveolar epithelial cells in primary culture remain the gold standard for the study of the function and dysfunction of the alveolar epithelium in physiological and pathological conditions. Indeed, immortalized cell lines such as A549 cells do not exhibit the complex characteristics and phenotypes of primary cells, whereas alveolar epithelial cells in primary culture recapitulate the main properties of the alveolar epithelium, in particular the ability to form a polarized and tight barrier14,15. Unfortunately, these cells are very resistant to conventional transfection techniques, such as those utilizing liposomes, making the use of a promoter-induced system such as Tet-Off very difficult.
The posttranscriptional modulation of mRNAs is one of the most effective methods for rapidly modulating the gene expression of a transcript16. The mRNA 3&#39; untranslated region (3&#39; UTR) plays an important role in this mechanism. It has been shown that, unlike the 5&#39; UTR, there is an exponential correlation between the length of the 3&#39; UTR and the cellular and morphological complexities of an organism. This correlation suggests that the 3&#39; UTR, like the mRNA coding regions, has been subjected to natural selection to allow for increasingly complex posttranscriptional modulation throughout evolution17. The 3&#39; UTR contains several binding sites for proteins and miRNAs that affect the stability and translation of the transcript.
In the present work, we developed a tool to investigate the role of highly conserved domains in the 3&#39; UTR of a GOI for the control of transcript stability. We focused on the epithelial sodium channel, alpha subunit (&#945;ENaC), which plays a key role in alveolar epithelial physiology18. Alveolar epithelial cells in primary culture were successfully transiently transfected with the two components of the Tet-Off system, which allows for the study of the role of the 3&#39; UTR in mRNA stability with a system that minimally affects cell physiology and metabolism in comparison to the use of transcription inhibitors with other protocols. A cloning strategy was developed to differentiate the expression of the GOI from that of the endogenous gene using a nonendogenously expressed epitope (V5). The response and regulatory plasmids were then transferred into alveolar epithelial cells using a pipette electroporation technique. Subsequently, the expression of the transcript was measured by incubating the cells with doxycycline at different time intervals. The half-life of the transcript was evaluated by RT-qPCR with a modified Cq method using the transfected tTA-Ad mRNA product for normalization. Through our protocol, we offer a convenient way for studying the posttranscriptional modulation of a transcript under different conditions and defining the involvement of the untranslated regions in more detail.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Actinomycin D</td>
			<td>Sigma-Aldrich</td>
			<td>A9415</td>
			<td></td>
		</tr>
		<tr>
			<td>Ampicillin</td>
			<td>Sigma-Aldrich</td>
			<td>A1593</td>
			<td></td>
		</tr>
		<tr>
			<td>Bright-LineHemacytometer</td>
			<td>Sigma-Aldrich</td>
			<td>Z359629</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloroform - Molecular biology grade</td>
			<td>Sigma-Aldrich</td>
			<td>C2432</td>
			<td></td>
		</tr>
		<tr>
			<td>ClaI</td>
			<td>New England Biolabs</td>
			<td>R0197S</td>
			<td></td>
		</tr>
		<tr>
			<td>Cycloheximide</td>
			<td>Sigma-Aldrich</td>
			<td>C7698</td>
			<td></td>
		</tr>
		<tr>
			<td>DM IL LED Inverted Microscope with Phase Contrast</td>
			<td>Leica</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>DNase I, Amplification Grade</td>
			<td>Invitrogen</td>
			<td>18068015</td>
			<td></td>
		</tr>
		<tr>
			<td>Doxycycline hyclate</td>
			<td>Sigma-Aldrich</td>
			<td>D9891-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#8217;s Phosphate-buffered Saline (D-PBS), without calcium and magnesium</td>
			<td>Wisent Bioproducts</td>
			<td>311-425-CL</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol - Molecular biology grade</td>
			<td>Fisher Scientific</td>
			<td>BP2818100</td>
			<td></td>
		</tr>
		<tr>
			<td>Excella E25 ConsoleIncubatorShaker</td>
			<td>Eppendorf</td>
			<td>1220G76</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma-Aldrich</td>
			<td>G5516</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES pH 7.3</td>
			<td>Sigma-Aldrich</td>
			<td>H3784</td>
			<td></td>
		</tr>
		<tr>
			<td>Heracell 240i</td>
			<td>ThermoFisher Scientific</td>
			<td>51026420</td>
			<td></td>
		</tr>
		<tr>
			<td>iScript cDNA Synthesis Kit</td>
			<td>Bio-Rad Laboratories</td>
			<td>1708890</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropanol - Molecular biology grade</td>
			<td>Sigma-Aldrich</td>
			<td>I9516</td>
			<td></td>
		</tr>
		<tr>
			<td>LB Broth (Lennox)</td>
			<td>Sigma-Aldrich</td>
			<td>L3022</td>
			<td></td>
		</tr>
		<tr>
			<td>LB Broth with agar (Lennox)</td>
			<td>Sigma-Aldrich</td>
			<td>L2897</td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamine</td>
			<td>Sigma-Aldrich</td>
			<td>G7513</td>
			<td></td>
		</tr>
		<tr>
			<td>Lipopolysaccharides fromPseudomonas aeruginosa10</td>
			<td>Sigma-Aldrich</td>
			<td>L9143</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM, powder</td>
			<td>Gibco</td>
			<td>61100103</td>
			<td></td>
		</tr>
		<tr>
			<td>MicroAmp Optical 96-Well Reaction Plate</td>
			<td>Applied Biosystems</td>
			<td>N8010560</td>
			<td></td>
		</tr>
		<tr>
			<td>MicroAmp Optical Adhesive Film</td>
			<td>Applied Biosystems</td>
			<td>4360954</td>
			<td></td>
		</tr>
		<tr>
			<td>MSC-Advantage Class II Biological Safety Cabinets</td>
			<td>ThermoFisher Scientific</td>
			<td>51025413</td>
			<td></td>
		</tr>
		<tr>
			<td>Mupid-exU electrophoresis system</td>
			<td>Takara Bio</td>
			<td>AD140</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoDrop 2000c</td>
			<td>ThermoFisher Scientific</td>
			<td>ND-2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Neon Transfection System 10 &#181;L Kit</td>
			<td>Invitrogen</td>
			<td>MPK1025</td>
			<td></td>
		</tr>
		<tr>
			<td>Neon Transfection System Starter Pack</td>
			<td>Invitrogen</td>
			<td>MPK5000S</td>
			<td></td>
		</tr>
		<tr>
			<td>NheI</td>
			<td>New England Biolabs</td>
			<td>R0131S</td>
			<td></td>
		</tr>
		<tr>
			<td>One Shot OmniMAX 2 T1RChemically CompetentE. coli</td>
			<td>Invitrogen</td>
			<td>C854003</td>
			<td></td>
		</tr>
		<tr>
			<td>pcDNA3 vector</td>
			<td>ThermoFisher Scientific</td>
			<td>V790-20</td>
			<td></td>
		</tr>
		<tr>
			<td>pcDNA3-EGFP plasmid</td>
			<td>Addgene</td>
			<td>13031</td>
			<td></td>
		</tr>
		<tr>
			<td>PlatinumTaqDNA Polymerase High Fidelity</td>
			<td>Invitrogen</td>
			<td>11304011</td>
			<td></td>
		</tr>
		<tr>
			<td>pTet-Off Advanced vector</td>
			<td>Takara Bio</td>
			<td>631070</td>
			<td></td>
		</tr>
		<tr>
			<td>pTRE-Tight vector</td>
			<td>Takara Bio</td>
			<td>631059</td>
			<td></td>
		</tr>
		<tr>
			<td>Purified alveolar epithelial cells</td>
			<td>n.a.</td>
			<td>n.a.</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAEX II Gel Extraction Kit</td>
			<td>QIAGEN</td>
			<td>20021</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAGEN Plasmid Maxi Kit</td>
			<td>QIAGEN</td>
			<td>12162</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAprep Spin Miniprep Kit</td>
			<td>QIAGEN</td>
			<td>27104</td>
			<td></td>
		</tr>
		<tr>
			<td>QuantStudio 6 and 7 Flex Real-Time PCR System Software</td>
			<td>Applied Biosystems</td>
			<td>n.a.</td>
			<td></td>
		</tr>
		<tr>
			<td>QuantStudio 6 Flex Real-Time PCR System, 96-well Fast</td>
			<td>Applied Biosystems</td>
			<td>4485697</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Rat TNF-alpha Protein</td>
			<td>R&#38;D Systems</td>
			<td>510-RT-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Septra</td>
			<td>Sigma-Aldrich</td>
			<td>A2487</td>
			<td></td>
		</tr>
		<tr>
			<td>Shrimp Alkaline Phosphatase (rSAP)</td>
			<td>New England Biolabs</td>
			<td>M0371S</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium bicarbonate</td>
			<td>Sigma-Aldrich</td>
			<td>S5761</td>
			<td></td>
		</tr>
		<tr>
			<td>SsoAdvanced Universal SYBR Green Supermix</td>
			<td>Bio-Rad Laboratories</td>
			<td>1725270</td>
			<td></td>
		</tr>
		<tr>
			<td>SuperScript IV Reverse Transcriptase</td>
			<td>Invitrogen</td>
			<td>18090010</td>
			<td></td>
		</tr>
		<tr>
			<td>T4 DNA Ligase</td>
			<td>ThermoFisher Scientific</td>
			<td>EL0011</td>
			<td></td>
		</tr>
		<tr>
			<td>Tet System Approved FBS</td>
			<td>Takara Bio</td>
			<td>631367</td>
			<td></td>
		</tr>
		<tr>
			<td>Tobramycin</td>
			<td>Sigma-Aldrich</td>
			<td>T4014</td>
			<td></td>
		</tr>
		<tr>
			<td>TRIzol Reagent</td>
			<td>Invitrogen</td>
			<td>15596018</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.05%), phenol red</td>
			<td>Gibco</td>
			<td>25300054</td>
			<td></td>
		</tr>
		<tr>
			<td>UltraPure Agarose</td>
			<td>Invitrogen</td>
			<td>16500500</td>
			<td></td>
		</tr>
		<tr>
			<td>Water, Molecular biology Grade</td>
			<td>Wisent Bioproducts</td>
			<td>809-115-EL</td>
			<td></td>
		</tr>
	</tbody>
</table>

efficient transcriptionally controlled plasmid expression system for investigation of the stability of mrna transcripts in primary alveolar epithelial cells

Studying posttranscriptional regulation is fundamental to understanding the modulation of a given messenger RNA (mRNA) and its impact on cell homeostasis and metabolism. Indeed, fluctuations in transcript expression could modify the translation efficiency and ultimately the cellular activity of a transcript. Several experimental approaches have been developed to investigate the half-life of mRNA although some of these methods have limitations that prevent the proper study of posttranscriptional modulation. A promoter induction system can express a gene of interest under the control of a synthetic tetracycline-regulated promoter. This method allows the half-life estimation of a given mRNA under any experimental condition without disturbing cell homeostasis. One major drawback of this method is the necessity to transfect cells, which limits the use of this technique in isolated primary cells that are highly resistant to conventional transfection techniques. Alveolar epithelial cells in primary culture have been used extensively to study the cellular and molecular biology of the alveolar epithelium. The unique characteristics and phenotype of primary alveolar cells make it essential to study the posttranscriptional modulations of genes of interest in these cells. Therefore, our aim was to develop a novel tool to investigate the posttranscriptional modulations of mRNAs of interest in alveolar epithelial cells in primary culture. We designed a fast and efficient transient transfection protocol to insert a transcriptionally controlled plasmid expression system into primary alveolar epithelial cells. This cloning strategy, using a viral epitope to tag the construct, allows for the easy discrimination of construct expression from that of endogenous mRNAs. Using a modified &#916;&#916; quantification cycle (Cq) method, the expression of the transcript can then be quantified at different time intervals to measure its half-life. Our data demonstrate the efficiency of this novel approach in studying posttranscriptional regulation in various pathophysiological conditions in primary alveolar epithelial cells.

This protocol was successfully used to generate a Tet-Off transcriptionally controlled plasmid expression system to evaluate the importance of different portions of the &#945;ENaC 3&#39; UTR in the modulation of transcript stability in primary alveolar epithelial cells.
The first step in the implementation of this system was to establish a fast, easy, and efficient transfection technique for alveolar epithelial cells in primary ...

Watch this Scientific Journal Video about Efficient Transcriptionally Controlled Plasmid Expression System for Investigation of the Stability of mRNA Transcripts in Primary Alveolar Epithelial Cells a

Efficient Transcriptionally Controlled Plasmid Expression System for Investigation of the Stability of mRNA Transcripts in Primary Alveolar Epithelial Cells

Here, we present a tool that can be used to study the posttranscriptional modulation of a transcript in primary alveolar epithelial cells by using an inducible expression system coupled to a pipette electroporation technique.

Studying posttranscriptional regulation is fundamental to understanding the modulation of a given messenger RNA (mRNA) and its impact on cell homeostasis ...

So our model allows study of the post-transcriptional modulation of a specific transcript in alveolar epithelial cells in primary culture and their physiological and pathophysiological conditions. So the transient transfection of primary alveolar epithelial cells has minimal effect on cell physiology and metabolisms, which poses a clear advantage over classic protocols using transcription inhibitors. For the generation of a response plasmid expressing a gene of interest, the sequence of the gene, and the multiple cloning sites of the inducible vector have to be analyzed to identify the recognition sequences in the multiple cloning sites that are not present internally in the gene.Using high fidelity taq polymerase and standard overlap PCR techniques, flank the gene of interest with two selected restriction enzyme recognition sites using designer primers. A sequence in coding the V5 epitope upstream of the gene of interest must be included to distinguish the expression of the transfected gene from endogenous expression. Mutants can be generated by sequential deletion to study the effects of different three prime untranslated regions on the stability of the mRNA of the gene using reverse primers encoding a polyadenylation site that gradually deletes the three prime end of the untranslated region.Ultimately, the insertion of the gene of interest can be confirmed by restriction analysis. The gene orientation and the absence of mutations potentially introduced during rtPCR can be confirmed by sequencing. For the transfection of primary rat lung type two alveolar epithelial cells, seed the cells at a one times 10 to the sixth cells per square centimeter in 100 millimeter Petri dishes in the presence of complete minimum essential medium.Culture for 24 hours at 37 degrees Celsius in 5%carbon dioxide with humidity. The next day, add 500 microliters of complete medium without antibiotic to each well of a new 12 well plate and pre-warm the plate at 37 degrees Celsius for 30 minutes. During this incubation, add one microgram of the response plasmid and one microgram of regulatory vector to one 1.5 milliliter tube per well.Wash the alveolar epithelial cells with 10 milliliters per well of 37 degrees Celsius PBS without calcium or magnesium and treat the cells with five milliliters per well of 37 degrees Celsius 0.05%trypsin for two to four minutes in the cell culture incubator. When the cells have detached, neutralize the trypsin with 10 milliliters per well of complete medium without antibiotic and collect the cells into a new 50 milliliter tube. Wash the dish with four milliliters of fresh medium to collect any remaining cells and sediment the cells by centrifugation.Resuspend the pellet in one milliliter of PBS for counting and centrifuge the cells again. Resuspend the pellet at a density of four times 10 to the seventh cells per milliliter of resuspension buffer and add four times 10 to the fifth cells to each tube of plasmid and vector with gentle mixing. Place one tube in the electroporation device and fill the tube with 3.5 milliliters of electrolytic buffer.Fully depress the piston to insert a gold plated electrode tip into a pipette and gently mix the tube contents. Carefully aspirate the cells with a pipette and insert the pipette into the electroporation station until a clicking sound is heard. Select the appropriate electroporation protocol for alveolar epithelial cells and press Start on the touchscreen.Immediately after the transfection, remove the pipette and transfer the cells into one well of the pre-warmed 12 well plate. When all of the cells have been electroporated and plated, place the plate in the cell culture incubator, replacing the supernatant in each well with complete medium with antibiotics after two days. The success of the transfection can be confirmed by the expression of EGFP as observed by fluorescence microscopy or flow cytometry using a control vector.To inhibit the transcription of the gene of interest, 72 hours post-transfection replace the supernatant with one milliliter per well of complete medium supplemented with one microgram per milliliter of freshly prepared adoxycycline. To assess the mRNA half-life of the gene of interest, return the plate to the cell culture incubator from 15 minutes to six hours. Washing one well with one milliliter of ice cold PBS before lysing the cells with 500 microliters of lysis buffer from a commercially available phenol chloroform RNA extraction kit and gentle shaking at each experimental time point.Then, isolate the RNA according to kit instructions and determine the RNA yield and purity by spectrophotometry at 230, 260, and 280 nanometers. To determine the stability of the isolated RNA, first treat one microgram of the total RNA from each sample with RNase free DNase one to remove any plasmid DNA traces. Use a commercially available cDNA synthesis kit with a blend of oligo dT and random hexomer primers to improve the reverse transcription efficiency to reverse transcribe the DNA depleted total RNA into cDNA according to manufacturer's instructions.Add 180 microliters of molecular biology grade water to the 20 microliters of the reaction mix to dilute the cDNA reaction at a five nanogram per microliter concentration and immediately dilute the cDNA mix with fresh molecular biology grade water to reach a 1.25 nanogram per microliter concentration. Combine five microliters of cyber green dye master mix with 0.1 microliter of molecular biology grade water, 0.45 microliters of 7.5 micromolar forward primer, 0.45 microliters of 7.5 micromolar reverse primer, and four microliters of 1.25 nanogram per microliter of cDNA to obtain a total reaction volume of 10 microliters. Place the samples in a qPCR thermocycler and amplify the V5 tag gene of interest and tetrocycline transactivator advance amplicons using the qPCR conditions as indicated and generate a high resolution melting curve to assess the specific melting temperatures of the desired amplicons and to ensure the absence of noise amplicon peaks.This pipette electroporation technique facilitates a 25 to 30%transfection efficiency rate as observed by the ratios of EGFP cells detected by fluorescence microscopy and flow cytometry. The treatment of alveolar epithelial cells with one microgram per milliliter of doxycycline has no significant impact on the expression of endogenous alpha ENaC mRNA at any time point during the treatment period. Using a transcriptionally controlled plasmid expression system as demonstrated, V5 alpha ENaC signal could be normalized according to the tetracycline transactivator advanced signal to determine the efficiency of transfection using the double delta quantification cycle method.The half-life of alpha ENaC mRNA is up to seven times shorter in the presence of the tetracycline off system than in the presence of actinomycin D, confirming that actinomycin D leads to an artifactual alpha ENaC mRNA stabilization. Further, cyclohexamide and tumor necrosis factor alpha treatment significantly decreased the stability of the transcript while lipopolysaccharides do not. Significant changes in the modulation of V5 alpha ENaC mRNA stability can be induced depending on the deleted and included regions of the three prime untranslated region.In addition, the over expression of specific RNA binding proteins decreases the stability of 5-alpha ENaC mRNA compared to transfection with an empty pcDNA three plasmid. This tool will be useful for querying novel insights into the post-transcriptional regulation of key genes involved into the function of alveolar epithelium and their physiological or pathological conditions.

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Unit 1

Additional Roles of RNA

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RNA Interference-based Investigation of the Function of Heat Shock Protein 27 during Corneal Epithelial Wound Healing

Small interfering RNA (siRNA) is among the most widely used RNA interference methods for the short-term silencing of protein-coding genes. siRNA is a synthetic RNA duplex created to specifically target a mRNA transcript to induce its degradation and it has been used to identify novel pathways in various cellular processes. Few reports exist regarding the role of phosphorylated heat shock protein 27 (HSP27) in corneal epithelial wound healing. Herein, cultured human corneal epithelial cells were divided into a scrambled control-siRNA transfected group and a HSP27-specific siRNA-transfected group. Scratch-induced directional wounding assays, and western blotting, and flow cytometry were then performed. We conclude that HSP27 has roles in corneal epithelial wound healing that may involve epithelial cell apoptosis and migration. Here, step-by-step descriptions of sample preparation and the study protocol are provided.

Herein, we present a protocol to use heat shock protein 27 (HSP27)-specific small interfering RNA to assess the function of HSP27 during corneal epithelial wound healing. RNA interference is the best method for effectively knocking-down gene expression to investigate protein function in various cell types.

Small interfering RNA (siRNA) is among the most widely used RNA interference methods for the short-term silencing of protein-coding genes. siRNA is a ...

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 ...

Inducible T7 RNA Polymerase-mediated Multigene Expression System, pMGX

Co-expression of multiple proteins is increasingly essential for synthetic biology, studying protein-protein complexes, and characterizing and harnessing biosynthetic pathways. In this manuscript, the use of a highly effective system for the construction of multigene synthetic operons under the control of an inducible T7 RNA polymerase is described. This system allows many genes to be expressed simultaneously from one plasmid. Here, a set of four related vectors, pMGX-A, pMGX-hisA, pMGX-K, and pMGX-hisK, with either the ampicillin or kanamycin resistance selectable marker (A and K) and either possessing or lacking an N-terminal hexahistidine tag (his) are disclosed. Detailed protocols for the construction of synthetic operons using this vector system are provided along with the corresponding data, showing that a pMGX-based system containing five genes can be readily constructed and used to produce all five encoded proteins in Escherichia coli. This system and protocol enables researchers to routinely express complex multi-component modules and pathways in E. coli.

This study describes methods for the T7-mediated co-expression of multiple genes from a single plasmid in Escherichia coli using the pMGX plasmid system.

Co-expression of multiple proteins is increasingly essential for synthetic biology, studying protein-protein complexes, and characterizing and harnessing ...

Controllable Ion Channel Expression through Inducible Transient Transfection

Transfection, the delivery of foreign nucleic acids into a cell, is a powerful tool in protein research. Through this method, ion channels can be investigated through electrophysiological analysis, biochemical characterization, mutational studies, and their effects on cellular processes. Transient transfections offer a simple protocol in which the protein becomes available for analysis within a few hours to days. Although this method presents a relatively straightforward and time efficient protocol, one of the critical components is calibrating the expression of the gene of interest to physiological relevant levels or levels that are suitable for analysis. To this end, many different approaches that offer the ability to control the expression of the gene of interest have emerged. Several stable cell transfection protocols provide a way to permanently introduce a gene of interest into the cellular genome under the regulation of a tetracycline-controlled transcriptional activation. While this technique produces reliable expression levels, each gene of interest requires a few weeks of skilled work including calibration of a killing curve, selection of cell colonies, and overall more resources. Here we present a protocol that uses transient transfection of the Transient Receptor Potential cation channel subfamily V member 1 (TRPV1) gene in an inducible system as an efficient way to express a protein in a controlled manner which is essential in ion channel analysis. We demonstrate that using this technique, we are able to perform calcium imaging, whole cell, and single channel analysis with controlled channel levels required for each type of data collection with a single transfection. Overall, this provides a replicable technique that can be used to study ion channels structure and function.

Studying ion channels through a heterologously expressing system has become a core technique in biomedical research. In this manuscript, we present a time efficient method to achieve tightly controlled ion channel expression by performing transient transfection under the control of an inducible promoter.

Transfection, the delivery of foreign nucleic acids into a cell, is a powerful tool in protein research. Through this method, ion channels can be ...

In Vitro Bioluminescence Assay to Characterize Circadian Rhythm in Mammary Epithelial Cells

The circadian rhythm is a fundamental physiological process present in all organisms that regulates biological processes ranging from gene expression to sleep behavior. In vertebrates, circadian rhythm is controlled by a molecular oscillator that functions in both the suprachiasmatic nucleus (SCN; central pacemaker) and individual cells comprising most peripheral tissues. More importantly, disruption of circadian rhythm by exposure to light-at-night, environmental stressors and/or toxicants is associated with increased risk of chronic diseases and aging. The ability to identify agents that can disrupt central and/or peripheral biological clocks, and agents that can prevent or mitigate the effects of circadian disruption, has significant implications for prevention of chronic diseases. Although rodent models can be used to identify exposures and agents that induce or prevent/mitigate circadian disruption, these experiments require large numbers of animals. In vivo studies also require significant resources and infrastructure, and require researchers to work all night. Thus, there is an urgent need for a cell-type appropriate in vitro system to screen for environmental circadian disruptors and enhancers in cell types from different organs and disease states. We constructed a vector that drives transcription of the destabilized luciferase in eukaryotic cells under the control of the human PERIOD 2 gene promoter. This circadian reporter construct was stably transfected into human mammary epithelial cells, and circadian responsive reporter cells were selected to develop the in vitro bioluminescence assay. Here, we present a detailed protocol to establish and validate the assay. We further provide details for proof of concept experiments demonstrating the ability of our in vitro assay to recapitulate the in vivo effects of various chemicals on the cellular biological clock. The results indicate that the assay can be adapted to a variety of cell types to screen for both environmental disruptors and chemopreventive enhancers of circadian clocks.

In Vitro Bioluminescence Assay to Characterize Circadian Rhythm in Mammary Epithelial Cells

An in vitro bioluminescence assay to determine cellular circadian rhythm in mammary epithelial cells is presented. This method utilizes mammalian cell reporter plasmids expressing destabilized luciferase under the control of the PERIOD 2 gene promoter. It can be adapted to other cell types to evaluate organ-specific effects on circadian rhythm.

The circadian rhythm is a fundamental physiological process present in all organisms that regulates biological processes ranging from gene expression to ...

Transient Expression of Foreign Genes in Insect Cells (sf9) for Protein Functional Assay

The transient gene expression system is one of the most important technologies for performing protein functional analysis in the baculovirus in vitro cell culture system. This system was developed to express foreign genes under the control of the baculoviral promoter in transient expression plasmids. Furthermore, this system can be applied to a functional assay of either the baculovirus itself or foreign proteins. The most widely and commercially available transient gene expression system is developed based on the immediate-early gene (IE) promoter of Orgyia pseudotsugata multicapsid nucleopolyhedrovirus (OpMNPV). However, a low expression level of foreign genes in insect cells was observed. Therefore, a transient gene expression system was constructed for improving protein expression. In this system, recombinant plasmids were constructed to contain the target sequence under the control of the Drosophila heat shock 70 (Dhsp70) promoter. This protocol presents the application of this heat shock-based pDHsp/V5-His (V5 epitope with 6 histidine)/Spodoptera frugiperda cell (sf9 cell) system; this system is available not only for gene expression but also for evaluating the anti-apoptotic activity of candidate proteins in insect cells. Furthermore, this system can be either transfected with one recombinant plasmid or co-transfected two potentially functionally antagonistic recombinant plasmids in insect cells. The protocol demonstrates the efficiency of this system and provides a practical case of this technique.

Transient Expression of Foreign Genes in Insect Cells sf9 for Protein Functional Assay

This protocol describes a heat shock-induced protein expression system (pDHsp/V5-His/sf9 cell system), which can be used for either expressing foreign proteins or evaluating the anti-apoptotic activity of potential foreign proteins and their truncated amino acids in insect cells.

The transient gene expression system is one of the most important technologies for performing protein functional analysis in the baculovirus in vitro cell ...

Efficient Production and Identification of CRISPR/Cas9-generated Gene Knockouts in the Model System Danio rerio

Characterization of the clustered, regularly interspaced, short, palindromic repeat (CRISPR) system of Streptococcus pyogenes has enabled the development of a customizable platform to rapidly generate gene modifications in a wide variety of organisms, including zebrafish. CRISPR-based genome editing uses a single guide RNA (sgRNA) to target a CRISPR-associated (Cas) endonuclease to a genomic DNA (gDNA) target of interest, where the Cas endonuclease generates a double-strand break (DSB). Repair of DSBs by error-prone mechanisms lead to insertions and/or deletions (indels). This can cause frameshift mutations that often introduce a premature stop codon within the coding sequence, thus creating a protein-null allele. CRISPR-based genome engineering requires only a few molecular components and is easily introduced into zebrafish embryos by microinjection. This protocol describes the methods used to generate CRISPR reagents for zebrafish microinjection and to identify fish exhibiting germline transmission of CRISPR-modified genes. These methods include in vitro transcription of sgRNAs, microinjection of CRISPR reagents, identification of indels induced at the target site using a PCR-based method called a heteroduplex mobility assay (HMA), and characterization of the indels using both a low throughput and a powerful next-generation sequencing (NGS)-based approach that can analyze multiple PCR products collected from heterozygous fish. This protocol is streamlined to minimize both the number of fish required and the types of equipment needed to perform the analyses. Furthermore, this protocol is designed to be amenable for use by laboratory personal of all levels of experience including undergraduates, enabling this powerful tool to be economically employed by any research group interested in performing CRISPR-based genomic modification in zebrafish.

Efficient Production and Identification of CRISPR/Cas9-generated Gene Knockouts in the Model System Danio rerio

Targeted genome editing in the model system Danio rerio (zebrafish) has been greatly facilitated by the emergence of CRISPR-based approaches. Herein, we describe a streamlined, robust protocol for generation and identification of CRISPR-derived nonsense alleles that incorporates the heteroduplex mobility assay and identification of mutations using next-generation sequencing.

Characterization of the clustered, regularly interspaced, short, palindromic repeat (CRISPR) system of Streptococcus pyogenes has enabled the development ...

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. ...

CRISPR-Mediated Reorganization of Chromatin Loop Structure

Recent studies have clearly shown that long-range, three-dimensional chromatin looping interactions play a significant role in the regulation of gene expression, but whether looping is responsible for or a result of alterations in gene expression is still unknown. Until recently, how chromatin looping affects the regulation of gene activity and cellular function has been relatively ambiguous, and limitations in existing methods to manipulate these structures prevented in-depth exploration of these interactions. To resolve this uncertainty, we engineered a method for selective and reversible chromatin loop re-organization using CRISPR-dCas9 (CLOuD9). The dynamism of the CLOuD9 system has been demonstrated by successful localization of CLOuD9 constructs to target genomic loci to modulate local chromatin conformation. Importantly, the ability to reverse the induced contact and restore the endogenous chromatin conformation has also been confirmed. Modulation of gene expression with this method establishes the capacity to regulate cellular gene expression and underscores the great potential for applications of this technology in creating stable de novo chromatin loops that markedly affect gene expression in the contexts of cancer and development.

Chromatin looping plays a significant role in gene regulation; however, there have been no technological advances that allow for selective and reversible modification of chromatin loops. Here we describe a powerful system for chromatin loop re-organization using CRISPR-dCas9 (CLOuD9), demonstrated to selectively and reversibly modulate gene expression at targeted loci.

Recent studies have clearly shown that long-range, three-dimensional chromatin looping interactions play a significant role in the regulation of gene ...

Purification of Low-abundant Cells in the Drosophila Visual System

Recent improvements in the sensitivity of next generation sequencing have facilitated the application of transcriptomic and genomic analyses to small numbers of cells. Utilizing this technology to study development in the Drosophila visual system, which boasts a wealth of cell type-specific genetic tools, provides a powerful approach for addressing the molecular basis of development with precise cellular resolution. For such an approach to be feasible, it is crucial to have the capacity to reliably and efficiently purify cells present at low abundance within the brain. Here, we present a method that allows efficient purification of single cell clones in genetic mosaic experiments. With this protocol, we consistently achieve a high cellular yield after purification using fluorescence activated cell sorting (FACS) (~25% of all labeled cells), and successfully performed transcriptomics analyses on single cell clones generated through mosaic analysis with a repressible cell marker (MARCM). This protocol is ideal for applying transcriptomic and genomic analyses to specific cell types in the visual system, across different stages of development and in the context of different genetic manipulations.

Here, we present a cell dissociation protocol for efficiently isolating cells present at low abundance within the Drosophila visual system through fluorescence activated cell sorting (FACS).

Recent improvements in the sensitivity of next generation sequencing have facilitated the application of transcriptomic and genomic analyses to small ...