Name: a quantitative measurement of reactive oxygen species and senescence-associated secretory phenotype in normal human fibroblasts during oncogene-induced senescence
Uploaded: 2018-08-12T13:00:00
Description: Watch this Scientific Journal Video about A Quantitative Measurement of Reactive Oxygen Species and Senescence-associated Secretory Phenotype in Normal Human Fibroblasts During Oncogene-induced Senesc

This work was supported by a grant from the National Research Foundation of Korea (2015R1D1A1A01060839) (to Young Yeon Kim) and by a National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2016R1A2B2008887, No. 2016R1A5A2007009) (to Jeanho Yun).

1. Inducing Oncogene-induced Senescence
<ol>
	<li>Preparing an H -RasV12 retrovirus
	<ol>
		<li>Coat the 100 mm culture dish by adding 2 mL of 0.001% poly-L-lysine/phosphate buffered saline (PBS) for 5 min at room temperature.</li>
		<li>Remove the poly-L-lysine solution using a glass pipette connected to a vacuum and wash the culture dish by adding 2 mL of 1x PBS.</li>
		<li>Plate 3 x 106 ecotropic BOSC-23 packaging cells on the coated culture dish with Dulbecco&#39;s Modified Eagle Medium ...

<ol>
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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+serial+cultivation+of+human+diploid+cell+strains.">The serial cultivation of human diploid cell strains.</a> Experimental Cell Research. 25, 585-621 (1961).</li><li>Campisi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aging,+cellular+senescence,+and+cancer.">Aging, cellular senescence, and cancer.</a> Annual Review of Physiology. 75, 685-705 (2013).</li><li>Braig, 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=Oncogene-induced+senescence+as+an+initial+barrier+in+lymphoma+development.">Oncogene-induced senescence as an initial barrier in lymphoma development.</a> Nature. 436 (7051), 660-665 (2005).</li><li>Michaloglou, 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=BRAFE600-associated+senescence-like+cell+cycle+arrest+of+human+naevi.">BRAFE600-associated senescence-like cell cycle arrest of human naevi.</a> Nature. 436 (7051), 720-724 (2005).</li><li>Collado, 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=Tumour+biology:+senescence+in+premalignant+tumours.">Tumour biology: senescence in premalignant tumours.</a> Nature. 436 (7051), 642 (2005).</li><li>Malaquin, N., Martinez, A., Rodier, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Keeping+the+senescence+secretome+under+control:+Molecular+reins+on+the+senescence-associated+secretory+phenotype.">Keeping the senescence secretome under control: Molecular reins on the senescence-associated secretory phenotype.</a> Experimental Gerontology. 82, 39-49 (2016).</li><li>Kuilman, T., Michaloglou, C., Mooi, W. 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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=Ras+proteins+induce+senescence+by+altering+the+intracellular+levels+of+reactive+oxygen+species.">Ras proteins induce senescence by altering the intracellular levels of reactive oxygen species.</a> The Journal of Biological Chemistry. 274 (12), 7936-7940 (1999).</li><li>Chen, Q., Ames, B. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Senescence-like+growth+arrest+induced+by+hydrogen+peroxide+in+human+diploid+fibroblast+F65+cells.">Senescence-like growth arrest induced by hydrogen peroxide in human diploid fibroblast F65 cells.</a> Proceedings of the National Academy of Sciences of the United States of America. 91 (10), 4130-4134 (1994).</li><li>Dumont, 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+replicative+senescence+biomarkers+by+sublethal+oxidative+stresses+in+normal+human+fibroblast.">Induction of replicative senescence biomarkers by sublethal oxidative stresses in normal human fibroblast.</a> Free Radical Biology &amp; Medicine. 28 (3), 361-373 (2000).</li><li>Blander, G., de Oliveira, R. M., Conboy, C. M., Haigis, M., Guarente, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superoxide+dismutase+1+knock-down+induces+senescence+in+human+fibroblasts.">Superoxide dismutase 1 knock-down induces senescence in human fibroblasts.</a> The Journal of Biological Chemistry. 278 (40), 38966-38969 (2003).</li><li>Packer, L., Fuehr, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low+oxygen+concentration+extends+the+lifespan+of+cultured+human+diploid+cells.">Low oxygen concentration extends the lifespan of cultured human diploid cells.</a> Nature. 267 (5610), 423-425 (1977).</li><li>Serra, V., von Zglinicki, T., Lorenz, M., Saretzki, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+superoxide+dismutase+is+a+major+antioxidant+in+human+fibroblasts+and+slows+telomere+shortening.">Extracellular superoxide dismutase is a major antioxidant in human fibroblasts and slows telomere shortening.</a> The Journal of Biological Chemistry. 278 (9), 6824-6830 (2003).</li><li>Rodier, F., Campisi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Four+faces+of+cellular+senescence.">Four faces of cellular senescence.</a> The Journal of Cell Biology. 192 (4), 547-556 (2011).</li><li>Munoz-Espin, D., Serrano, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+senescence:+from+physiology+to+pathology.">Cellular senescence: from physiology to pathology.</a> Nature Reviews. Molecular Cell Biology. 15 (7), 482-496 (2014).</li><li>Tchkonia, T., Zhu, Y., van Deursen, J., Campisi, J., Kirkland, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+senescence+and+the+senescent+secretory+phenotype:+therapeutic+opportunities.">Cellular senescence and the senescent secretory phenotype: therapeutic opportunities.</a> The Journal of Clinical Investigation. 123 (3), 966-972 (2013).</li><li>van Deursen, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+senescent+cells+in+ageing.">The role of senescent cells in ageing.</a> Nature. 509 (7501), 439-446 (2014).</li><li>Livak, K. J., Schmittgen, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+relative+gene+expression+data+using+real-time+quantitative+PCR+and+the+2(-Delta+Delta+C(T))+Method.">Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method.</a> Methods. 25 (4), 402-408 (2001).</li><li>Kim, Y. 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=Cooperation+between+p21+and+Akt+is+required+for+p53-dependent+cellular+senescence.">Cooperation between p21 and Akt is required for p53-dependent cellular senescence.</a> Aging Cell. 16 (5), 1094-1103 (2017).</li><li>Serrano, M., Lin, A. W., McCurrach, M. E., Beach, D., Lowe, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oncogenic+ras+provokes+premature+cell+senescence+associated+with+accumulation+of+p53+and+p16INK4a.">Oncogenic ras provokes premature cell senescence associated with accumulation of p53 and p16INK4a.</a> Cell. 88 (5), 593-602 (1997).</li><li>Wu, D., Yotnda, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+and+detection+of+reactive+oxygen+species+(ROS)+in+cancers.">Production and detection of reactive oxygen species (ROS) in cancers.</a> Journal of Visualized Experiments. (57), (2011).</li><li>Wojtala, 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=Methods+to+monitor+ROS+production+by+fluorescence+microscopy+and+fluorometry.">Methods to monitor ROS production by fluorescence microscopy and fluorometry.</a> Methods in Enzymology. 542, 243-262 (2014).</li><li>Duncan, F. 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=Age-associated+dysregulation+of+protein+metabolism+in+the+mammalian+oocyte.">Age-associated dysregulation of protein metabolism in the mammalian oocyte.</a> Aging Cell. 16 (6), 1381-1393 (2017).</li><li>Yang, L., Song, T., Chen, L., Soliman, H., Chen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nucleolar+repression+facilitates+initiation+and+maintenance+of+senescence.">Nucleolar repression facilitates initiation and maintenance of senescence.</a> Cell Cycle. 14 (22), 3613-3623 (2015).</li><li>Coppe, J. 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=Senescence-associated+secretory+phenotypes+reveal+cell-nonautonomous+functions+of+oncogenic+RAS+and+the+p53+tumor+suppressor.">Senescence-associated secretory phenotypes reveal cell-nonautonomous functions of oncogenic RAS and the p53 tumor suppressor.</a> PLoS Biology. 6 (12), 2853-2868 (2008).</li><li>Kosar, 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=Senescence-associated+heterochromatin+foci+are+dispensable+for+cellular+senescence,+occur+in+a+cell+type-+and+insult-dependent+manner+and+follow+expression+of+p16(ink4a).">Senescence-associated heterochromatin foci are dispensable for cellular senescence, occur in a cell type- and insult-dependent manner and follow expression of p16(ink4a).</a> Cell Cycle. 10 (3), 457-468 (2011).</li><li>Sharpless, N. E., Sherr, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Forging+a+signature+of+in+vivo+senescence.">Forging a signature of in vivo senescence.</a> Nature Reviews. Cancer. 15 (7), 397-408 (2015).</li><li>Baker, D. 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=Opposing+roles+for+p16Ink4a+and+p19Arf+in+senescence+and+ageing+caused+by+BubR1+insufficiency.">Opposing roles for p16Ink4a and p19Arf in senescence and ageing caused by BubR1 insufficiency.</a> Nature Cell Biology. 10 (7), 825-836 (2008).</li><li>Baker, D. 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=Clearance+of+p16Ink4a-positive+senescent+cells+delays+ageing-associated+disorders.">Clearance of p16Ink4a-positive senescent cells delays ageing-associated disorders.</a> Nature. 479 (7372), 232-236 (2011).</li><li>Baar, M. 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=Targeted+Apoptosis+of+Senescent+Cells+Restores+Tissue+Homeostasis+in+Response+to+Chemotoxicity+and+Aging.">Targeted Apoptosis of Senescent Cells Restores Tissue Homeostasis in Response to Chemotoxicity and Aging.</a> Cell. 169 (1), 132-147 (2017).</li><li>Farr, J. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+cellular+senescence+prevents+age-related+bone+loss+in+mice.">Targeting cellular senescence prevents age-related bone loss in mice.</a> Nature Medicine. 23 (9), 1072-1079 (2017).</li><li>Chang, 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=Clearance+of+senescent+cells+by+ABT263+rejuvenates+aged+hematopoietic+stem+cells+in+mice.">Clearance of senescent cells by ABT263 rejuvenates aged hematopoietic stem cells in mice.</a> Nature Medicine. 22 (1), 78-83 (2016).</li><li>Yosef, 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=Directed+elimination+of+senescent+cells+by+inhibition+of+BCL-W+and+BCL-XL.">Directed elimination of senescent cells by inhibition of BCL-W and BCL-XL.</a> Nature Communications. 7, 11190 (2016).</li><li>Jeon, O. 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Here, we have presented methods for monitoring intracellular ROS levels during H-Ras-induced senescence in WI-38 normal human fibroblasts. Intracellular ROS levels in live cells can be measured quantitatively using the cell-permeable reagent DCF-DA and flow cytometry. Upon cellular uptake, DCF-DA is deacetylated by intracellular esterases and, subsequently, oxidized by ROS to form highly fluorescent 2&#39;,7&#39;-dichlorofluorescein (DCF). DCF fluorescence can be detected by flow cytometry using an FL1 detector (green fl...

More than 50 years ago, Hayflick and Moorhead revealed that normal cells enter irreversible growth arrest upon the exhaustion of their proliferative potential after a certain number of cell divisions1. This phenomenon is now known as replicative senescence and is believed to strongly correlate with organismal aging2. Although the progressive erosion of telomeres is considered a major cause of replicative senescence, various cellular stresses, such as DNA damage, oncogenic activation, and oxidative stress, have been reported to induce another type of cellular senescence called &#34;premature senescence&#34; or &#34;stress-induced senescence&#34;. Interestingly, premature senescence plays a potent tumor-suppressive role upon the activation of oncogenes such as H-Ras and BRAF. Studies of mouse models and human tissues have produced strong evidence that biomarkers of cell senescence were predominantly present in premalignant lesions where oncogenic Ras and BRAF are activated but were diminished in malignant cancers that developed from these lesions3,4,5. Beyond its role in aging and tumor suppression, cellular senescence has been shown in previous studies to play a role in various physiological processes, including wound healing, tissue repair, immune surveillance, and embryonic development6.
Although growth arrest has been extensively studied as a hallmark of cellular senescence7, a significant body of evidence suggests that intracellular reactive oxygen species (ROS) also contributes to cellular senescence8. The elevation of ROS levels during various types of cellular senescence, including replicative senescence and oncogene-induced senescence (OIS), was originally reported decades ago9,10. A more directly, exogenous treatment with a sublethal dose of H2O2 induces senescence11,12. The inhibition of ROS-scavenging enzymes, such as SOD1, also causes premature senescence13. In contrast, low ambient oxygen conditions and increasing ROS scavenging delay the onset of senescence10,14,15. These results undoubtedly indicate that ROS are important mediators or determinants of cellular senescence induction. However, how ROS contribute to the induction of cellular senescence and how ROS levels are elevated during cellular senescence require further investigation.
Recent studies have revealed that senescent cells have potent paracrine activities on neighboring cells and tissues through an SASP16,17. In aged tissue, senescent cells promote age-related tissue dysfunctions via many pathways through SASP in addition to an autonomous depletion of proliferative cells. Various proinflammatory factors, such as IL-6, IL-8, TGF&#946;, and matrix metalloproteinases (MMPs), secreted by senescent cells, cause age-related tissue dysfunctions through the impairment of tissue homeostasis, destruction of the tissue architecture, senescence of neighboring cells, and sterile inflammation18,19. However, SASPs can have beneficial effects depending on the biological context. In addition, the heterogenetic nature of SASPs depends on the senescent cell type and the cell stage, emphasizing the need for further research19.
Here, we describe rapid and sensitive cytometry-based techniques for assessing intracellular ROS levels during OIS. In addition, methods for the analysis of SASP factors using quantitative real-time polymerase chain reaction (qPCR) and ELISA are introduced.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>REAGENTS</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>poly-L-lysine</td>
			<td>Sigma-Aldrich</td>
			<td>P2636</td>
			<td></td>
		</tr>
		<tr>
			<td>BOSC 23</td>
			<td>ATCC</td>
			<td>CRL-11269</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>GIBCO</td>
			<td>16000-044</td>
			<td></td>
		</tr>
		<tr>
			<td>penicillin/streptomycin</td>
			<td>wellgene</td>
			<td>LS202-02</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Hyclone</td>
			<td>SH30013.02</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>GIBCO</td>
			<td>12800-082</td>
			<td></td>
		</tr>
		<tr>
			<td>OPTI-MEM&#160;</td>
			<td>GIBCO</td>
			<td>31985-070</td>
			<td></td>
		</tr>
		<tr>
			<td>pBabe puro-H-RasV12&#160;</td>
			<td>Addgene</td>
			<td>1768</td>
			<td></td>
		</tr>
		<tr>
			<td>pGAG/pol</td>
			<td>Addgene</td>
			<td>14887</td>
			<td></td>
		</tr>
		<tr>
			<td>pVSVG</td>
			<td>Addgene</td>
			<td>1733</td>
			<td></td>
		</tr>
		<tr>
			<td>Turbofect</td>
			<td>Thermo Fisher Scientific</td>
			<td>R0531</td>
			<td></td>
		</tr>
		<tr>
			<td>polybrene</td>
			<td>Sigma-Aldrich</td>
			<td>H9268</td>
			<td>8 mg/ml</td>
		</tr>
		<tr>
			<td>puromycin</td>
			<td>Sigma-Aldrich</td>
			<td>P8833</td>
			<td>2 mg/ml&#160;</td>
		</tr>
		<tr>
			<td>formaldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>F8775</td>
			<td></td>
		</tr>
		<tr>
			<td>5-bromo-4-chloro-3-indolyl &#946; D-galactopyranoside (X-gal)</td>
			<td>Sigma-Aldrich</td>
			<td>B4252</td>
			<td></td>
		</tr>
		<tr>
			<td>potassium ferrocyanide</td>
			<td>Sigma-Aldrich</td>
			<td>B4252</td>
			<td></td>
		</tr>
		<tr>
			<td>potassium ferricyanide</td>
			<td>Sigma-Aldrich</td>
			<td>P9387</td>
			<td></td>
		</tr>
		<tr>
			<td>trypsin-EDTA</td>
			<td>wellgene</td>
			<td>LS015-01</td>
			<td></td>
		</tr>
		<tr>
			<td>DCF-DA</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>D6883</td>
			<td>10 mM&#160;</td>
		</tr>
		<tr>
			<td>Trizol</td>
			<td>Thermo Fisher Scientific</td>
			<td>15596026</td>
			<td></td>
		</tr>
		<tr>
			<td>MMLV Reverse transcriptase</td>
			<td>Promega</td>
			<td>M1701</td>
			<td></td>
		</tr>
		<tr>
			<td>SYBR Green PCR master 2X mix</td>
			<td>Takara</td>
			<td>PR820A</td>
			<td></td>
		</tr>
		<tr>
			<td>Random Primer</td>
			<td>Promega</td>
			<td>C118A</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Sigma-Aldrich</td>
			<td>P9416</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra-pure distilled water</td>
			<td>Invitrogen</td>
			<td>10977015</td>
			<td></td>
		</tr>
		<tr>
			<td>Human IL-6 ELISA assay</td>
			<td>PeproTech</td>
			<td>#900-TM16</td>
			<td></td>
		</tr>
		<tr>
			<td>Human IL-8 ELISA assay</td>
			<td>PeproTech</td>
			<td>#900_TM18</td>
			<td></td>
		</tr>
		<tr>
			<td>EQUIPMENTS</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>0.45 &#956;m syringe filter</td>
			<td>sartorius</td>
			<td>16555</td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>BEMIS&#160;</td>
			<td>PM-996</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>NIKON</td>
			<td>TS100</td>
			<td></td>
		</tr>
		<tr>
			<td>Flow cytometer</td>
			<td>BD Bioscience</td>
			<td>LSR Fortessa</td>
			<td></td>
		</tr>
		<tr>
			<td>Amicon Ultra-4ml</td>
			<td>Merk Millipore</td>
			<td>UFC800324</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoDrop spectrophotometer</td>
			<td>BioDrop</td>
			<td>80-3006-61</td>
			<td></td>
		</tr>
		<tr>
			<td>Real-time PCR System</td>
			<td>Applied Biosystems</td>
			<td>ABI Prism 7500</td>
			<td></td>
		</tr>
		<tr>
			<td>ELISA Reader</td>
			<td>Molecular Devices</td>
			<td>EMax microplate reader</td>
			<td></td>
		</tr>
	</tbody>
</table>

a quantitative measurement of reactive oxygen species and senescence-associated secretory phenotype in normal human fibroblasts during oncogene-induced senescence

Cellular senescence has been considered a state of irreversible growth arrest upon exhaustion of proliferative capacity or exposure to various stresses. Recent studies have extended the role of cellular senescence to various physiological processes, including development, wound healing, immune surveillance, and age-related tissue dysfunction. Although cell cycle arrest is a critical hallmark of cellular senescence, an increased intracellular reactive oxygen species (ROS) production has also been demonstrated to play an important role in the induction of cellular senescence. In addition, recent studies revealed that senescent cells exhibit potent paracrine activities on neighboring cells and tissues through a senescence-associated secretory phenotype (SASP). The sharp increase in interest regarding therapeutic strategies against cellular senescence emphasizes the need for a precise understanding of senescence mechanisms, including intracellular ROS and the SASP. Here, we describe protocols for quantitatively assessing intracellular ROS levels during H-Ras-induced cellular senescence using ROS-sensitive fluorescent dye and flow cytometry. In addition, we introduce sensitive techniques for the analysis of the induction of mRNA expression and secretion of SASP factors. These protocols can be applied to various cellular senescence models.

An example of H-Ras-induced senescence is shown in Figure 1. An infection of WI-38 normal human fibroblasts with the H-RasV12 retrovirus induced dramatic morphological changes (Figure 1B). In addition, as shown in Figure 1C, SA &#946;-gal staining activity was remarkably increased upon H-RasV12 expression. More than 70% of the cells showed SA &#946;-gal staining activity 6 d after the H-RasV12 retrov...

Watch this Scientific Journal Video about A Quantitative Measurement of Reactive Oxygen Species and Senescence-associated Secretory Phenotype in Normal Human Fibroblasts During Oncogene-induced Senesc

A Quantitative Measurement of Reactive Oxygen Species and Senescence-associated Secretory Phenotype in Normal Human Fibroblasts During Oncogene-induced Senescence

Intracellular ROS has been shown to play an important role in the induction of cellular senescence. Here, we describe a sensitive assay for quantifying ROS levels during cellular senescence. We also provide protocols for assessing the senescence-associated secretory phenotype, which reportedly contributes to various age-related dysfunctions.

Cellular senescence has been considered a state of irreversible growth arrest upon exhaustion of proliferative capacity or exposure to various stresses. ...

The overall goal of this procedure is to provide sensitive techniques for monitoring intracellular ROS levels and senescence-associated secretory phenotype, or SASP, during cellular senescence. Here, we demonstrate that these methods successfully reveal the increases in the levels of intracellular ROS and the SASP factors IL-6 and IL-8 during H-Ras-induced senescence in WI-38 normal human fibroblasts. These techniques allow monitoring changes in intracellular ROS levels during cellular senescence and the analysis of the expression of SASP factors.The main advantage of this method is that they can be applied to many different cellular senescence models. Therefore, this method can ultimately help us to understand the role of ROS and SASP in cellular senescence and to study the underlying regulatory mechanisms. Demonstrating the procedure will be Young Yeon Kim and Jee-Hyun Um from my laboratory.Begin this procedure by preparing the H-Ras retrovirus. First, seed ecotropic BOSC cells in a poly-L-lysine-coated culture dish, and culture at 37 degrees Celsius in a tissue culture incubator for one day. On the next day, transfect the BOSC cells with H-Ras retroviral DNA and packaging DNAs using transfection reagent according to the manufacturer's instructions.After eight hours of transfection, remove the transfection media and add eight milliliters of fresh media. Collect the media containing viral particles 48 hours later, and remove cellular debris by centrifugation. Next, filter the virus-containing media with a 0.45-micrometer syringe filter.Plate WI-38 cells in a 60-millimeter culture dish one day before harvest of H-Ras retrovirus, and culture for one day at 37 degrees Celsius in an incubator. On the next day, remove the growth medium, and add one milliliter of H-Ras virus media. Add an additional one milliliter of growth medium containing two microliters of polybrene stock solution, and incubate for one day at CO2 incubator.At 24 hours after infection, remove the virus media, wash the cells twice with PBS, and add the growth media. To remove non-infected cells, treat the cells for two days with two micrograms per milliliter of puromycin. Prepare fresh SA beta-gal staining solution by diluting the stock solution.Remove the culture media, and wash the cells once with PBS. Add fixation solution containing formaldehyde, and incubate for five minutes. Remove the fixation solution from the cells, and wash with PBS.Add freshly prepared SA beta-gal staining solution to cover the dish. Seal the dish with Parafilm to avoid drying the sample, and incubate at 37 degrees Celsius in an incubator without CO2. Check the staining status of the cells under microscope on the next day.SA beta-gal-positive cells will appear blue in the perinuclear region. Acquire an image of SA beta-gal staining with a CCD camera, and calculate the percentage of SA beta-gal-stained cells by counting the number of SA beta-gal-positive cells among at least 200 total cells. Plate two times 10 to the fifth WI-38 cells on a 60-millimeter culture dish, and induce senescence by infecting the cells with H-Ras retrovirus as described previously.At the desired time point for measurement of ROS, remove the growth medium and wash once with PBS. Detach the cells by treatment with trypsin/EDTA solution, and determine the cell count. Transfer one times 10 to the fifth cells into a 15-milliliter conical tube, and collect the cells by centrifugation.Remove the growth medium carefully, and add one milliliter of freshly prepared DCF-DA staining medium. Carefully resuspend the cell pellet, and incubate at 37 degrees Celsius for 30 minutes in the dark. Collect the cells by centrifugation and wash once with PBS.Resuspend the cells with one milliliter of PBS, and transfer the samples into a FACS tube. The DCF-DA fluorescence signal can be measured using a flow cytometer equipped with a 488-nanometer blue laser. First, run a non-stained control cell sample.In the dot plot of the forward scatter versus side scatter, select live cells and eliminate dead cells and cell debris by using a gating tool. Next, in the histogram displaying DCF-DA fluorescence signal, adjust the blue laser voltage to place the peak from the control cells at the left edge. Now, run each sample stained with DCF-DA, and record at least 10, 000 events.Induce senescence by infecting the cells with H-Ras retrovirus as described previously. At one day before harvest, wash the cells twice with PBS. Add three milliliters of DMEM without FBS, and culture the cells at 37 degrees Celsius in a tissue culture incubator for one day.After 24 hours, collect the conditioned medium, and store at negative 80 degrees Celsius for subsequent ELISA. Trypsinize the cells, and harvest the cells in a 1.5-milliliter microcentrifuge tube by centrifugation. Prepare total RNA using the conventional RNA extraction method, and generate cDNA from two micrograms of total RNA through a reverse transcription reaction.For real-time PCR, prepare SYBR Green PCR Master Mix for all reactions containing the forward and reverse primers for IL-6 or IL-8. Prepare the reaction mixture for each sample containing actin primers as an internal control. Add 48 microliters of Master Mix and two microliters of cDNA products diluted one to three to each well in a 96-well optical qPCR plate.Perform each reaction in triplicates. Set up the real-time PCR reaction program on the thermal cycler, and perform real-time PCR. Upon completion of the run, collect the threshold cycle values, or CT values, and calculate the mRNA levels of IL-6 or IL-8 after normalization to the actin levels.Thaw conditioned media harvested previously from senescent WI-38 cells. Remove cell debris by centrifugation at 500 g for five minutes. Concentrate the conditioned medium by 10-fold using a centrifugal filter with a pore size of 3, 000 dalton.Perform the ELISA with the appropriate IL-6 or IL-8 ELISA kit. First, coat the ELISA plate well with diluted IL-6 or IL-8 antibody by incubating the plate overnight at room temperature. After washing each well four times, add blocking buffer to each well, and incubate for one hour.Wash the plate four times. Add either serially diluted ELISA standards or concentrated conditioned medium samples, and incubate for two hours. After washing the plate, incubate the samples with a secondary antibody and streptavidin-HRP conjugate sequentially.Add 100 microliters of TMB substrate solution to each well, and incubate at room temperature for 20 minutes to allow for color development. Stop the reaction by adding stop solution. Read the absorbance of each well with an ELISA reader at 450 nanometer.Plot the standard curve for the generated standards. Calculate the concentrations of IL-6 and IL-8 in the conditioned medium according to the standard curves. Plot the results after normalization to the cell count.Infection of WI-38 normal human fibroblasts with H-Ras retrovirus induced dramatic changes in cellular morphology. SA beta-gal staining activity was observed in more than 70%of the cells, indicating that H-Ras expression induces cellular senescence in WI-38 cells within six days. DCF-DA staining analysis reveals that H-Ras expression also induces a significant increase in intracellular ROS levels.The increase in intracellular ROS levels is observed as early as two days after H-Ras expression and is maintained until the six-day time point. Real-time PCR analysis of the representative senescence-associated secretory factors IL-6 and IL-8 reveals that mRNA expression of IL-6 and IL-8 is remarkably increased in senescent WI-38 cells. ELISAs of conditioned medium confirmed that IL-6 and IL-8 secretion is also increased in H-Ras-induced senescent cells.Inducing cellular senescence through oncogene expression, DNA damage, or oxidative stress usually takes six to eight days. Once the cells are ready, ROS measurement can be conducted within two hour if performed properly. After mastery of these techniques, analysis of the mRNA and protein levels of SASP factors can be completed within one day.When analyzing ROS levels and SASP induction, it is important to confirm cellular senescence through SA beta-gal staining and additional method if necessary. In addition, it is critical to remember that the increase of ROS occurs in the early phase of senescence, whereas the development of SASP is detectable only after senescence is fully established. These techniques can be applied to a wide variety of cellular senescence models.After watching this video, you should have a good understanding of how to analyze ROS levels and SASP induction during cellular senescence.

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Research

JoVE Journal

Developmental Biology

Isolation and Quantitative Immunocytochemical Characterization of Primary Myogenic Cells and Fibroblasts from Human Skeletal Muscle

The repair and regeneration of skeletal muscle requires the action of satellite cells, which are the resident muscle stem cells. These can be isolated from human muscle biopsy samples using enzymatic digestion and their myogenic properties studied in culture. Quantitatively, the two main adherent cell types obtained from enzymatic digestion are: (i) the satellite cells (termed myogenic cells or muscle precursor cells), identified initially as CD56+ and later as CD56+/desmin+ cells and (ii) muscle-derived fibroblasts, identified as CD56&#8211; and TE-7+. Fibroblasts proliferate very efficiently in culture and in mixed cell populations these cells may overrun myogenic cells to dominate the culture. The isolation and purification of different cell types from human muscle is thus an important methodological consideration when trying to investigate the innate behavior of either cell type in culture. Here we describe a system of sorting based on the gentle enzymatic digestion of cells using collagenase and dispase followed by magnetic activated cell sorting (MACS) which gives both a high purity (&#62;95% myogenic cells) and good yield (~2.8 x 106 &#177; 8.87 x 105 cells/g tissue after 7 days in vitro) for experiments in culture. This approach is based on incubating the mixed muscle-derived cell population with magnetic microbeads beads conjugated to an antibody against CD56 and then passing cells though a magnetic field. CD56+ cells bound to microbeads are retained by the field whereas CD56&#8211; cells pass unimpeded through the column. Cell suspensions from any stage of the sorting process can be plated and cultured. Following a given intervention, cell morphology, and the expression and localization of proteins including nuclear transcription factors can be quantified using immunofluorescent labeling with specific antibodies and an image processing and analysis package.

The main adherent cell types derived from human muscle are myogenic cells and fibroblasts. Here, cell populations are enriched using magnetic-activated cell sorting based on the CD56 antigen. Subsequent immunolabelling with specific antibodies and use of image analysis techniques allows quantification of cytoplasmic and nuclear characteristics in individual cells.

The repair and regeneration of skeletal muscle requires the action of satellite cells, which are the resident muscle stem cells. These can be isolated ...

Establishment of Proliferative Tetraploid Cells from Nontransformed Human Fibroblasts

Polyploid (mostly tetraploid) cells are often observed in preneoplastic lesions of human tissues and their chromosomal instability has been considered to be responsible for carcinogenesis in such tissues. Although proliferative polyploid cells are requisite for analyzing chromosomal instability of polyploid cells, creating such cells from nontransformed human cells is rather challenging. Induction of tetraploidy by chemical agents usually results in a mixture of diploid and tetraploid populations, and most studies employed fluorescence-activated cell sorting or cloning by limiting dilution to separate tetraploid from diploid cells. However, these procedures are time-consuming and laborious. The present report describes a relatively simple protocol to induce proliferative tetraploid cells from normal human fibroblasts with minimum contamination by diploid cells. Briefly, the protocol is comprised of the following steps: arresting cells in mitosis by demecolcine (DC), collecting mitotic cells after shaking off, incubating collected cells with DC for an additional 3 days, and incubating cells in drug-free medium (They resume proliferation as tetraploid cells within several days). Depending on cell type, the collection of mitotic cells by shaking off might be omitted. This protocol provides a simple and feasible method to establish proliferative tetraploid cells from normal human fibroblasts. Tetraploid cells established by this method could be a useful model for studying chromosome instability and the oncogenic potential of polyploid human cells.

Although proliferative polyploid cells are necessary to analyze chromosomal instability of polyploid cells, creating such cells from nontransformed human cells is not easy. The present report describes relatively simple procedures to establish proliferative tetraploid cells free of a diploid population from normal human fibroblasts.

Polyploid (mostly tetraploid) cells are often observed in preneoplastic lesions of human tissues and their chromosomal instability has been considered to ...

Evaluation of Intracellular Location of Reactive Oxygen Species in Solea Senegalensis Spermatozoa

Oxidative stress is one of the important factors in decreasing sperm quality. Developing efficient protocols for detecting reactive oxygen species (ROS) in spermatozoa is of high importance in any species, but these methods are rarely used and even less in teleost. Cryopreservation is a useful technique in aquaculture for different purposes, including gene banking and guaranteed sperm availability throughout the year. Freezing/thawing procedures could cause ROS production and damage the sperm cells. Considering the prospective damage that an excess of ROS production could cause in spermatozoa depending on their localization, here a detailed methodology to detect H2O2 and to evaluate its intracellular localization by confocal microscopy is provided. For this purpose, a combination of 3 fluorochromes (2&#8242;,7&#8242;-Dichlorodihydrofluorescein diacetate (DCFH-DA), a live mitochondria stain and 4&#8242;,6-Diamidino-2-phenylindole dihydrochloride (DAPI)) are used to evaluate the co-localization of H2O2 with spermatozoa nuclei or mitochondria in Solea senegalesis sperm samples.

Evaluation of Intracellular Location of Reactive Oxygen Species in Solea Senegalensis Spermatozoa

This protocol describes a detailed methodology for detecting H2O2 localization within Solea senegalensis spermatozoa using a sensitive fluorochrome DCFH-DA for ROS, a live mitochondria stain for mitochondria, and DAPI for nuclei visualization, respectively. The protocol is designed to be performed within 2 h with either fresh or thawed spermatozoa.

Oxidative stress is one of the important factors in decreasing sperm quality. Developing efficient protocols for detecting reactive oxygen species (ROS) ...

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development

Kinase activity is crucial for a plethora of cellular functions, including cell proliferation, differentiation, migration, and apoptosis. During early embryonic development, kinase activity is highly dynamic and widespread across the embryo. Pharmacological and genetic approaches are commonly used to probe kinase activities. Unfortunately, it is challenging to achieve superior spatial and temporal resolution using these strategies. Furthermore, it is not feasible to control the kinase activity in a reversible fashion in live cells and multicellular organisms. Such a limitation remains a bottleneck for achieving a quantitative understanding of kinase activity during development and differentiation. This work presents an optogenetic strategy that takes advantage of a bicistronic system containing photoactivatable proteins Arabidopsis thaliana cryptochrome 2 (CRY2) and the N-terminal domain of cryptochrome-interacting basic-helix-loop-helix (CIBN). Reversible activation of the mitogen-activated protein kinase (MAPK) signaling pathway is achieved through light-mediated protein translocation in live cells. This approach can be applied to mammalian cell cultures and live vertebrate embryos. This bicistronic system can be generalized to control the activity of other kinases with similar activation mechanisms and can be applied to other model systems.

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development

This protocol describes an optogenetic strategy to modulate mitogen-activated protein kinase (MAPK) activity during cell differentiation and Xenopus embryonic development. This method allows for the reversible activation of the MAPK signaling pathway in mammalian cell culture and in multicellular live organisms, like Xenopus embryos, with high spatial and temporal resolution.

Kinase activity is crucial for a plethora of cellular functions, including cell proliferation, differentiation, migration, and apoptosis. During early ...

A Method for Characterizing Embryogenesis in Arabidopsis

Given the highly predictable nature of their development, Arabidopsis embryos have been used as a model for studies of morphogenesis in plants. However, early stage plant embryos are small and contain few cells, making them difficult to observe and analyze. A method is described here for characterizing pattern formation in plant embryos under a microscope using the model organism Arabidopsis. Following the clearance of fresh ovules using Hoyer's solution, the cell number in and morphology of embryos could be observed, and their developmental stage could be determined by differential interference contrast microscopy using a 100X oil immersion lens. In addition, the expression of specific marker proteins tagged with Green Fluorescent Protein (GFP) was monitored to annotate cell identity specification during embryo patterning by confocal laser scanning microscopy. Thus, this method can be used to observe pattern formation in wild-type plant embryos at the cellular and molecular levels, and to characterize the role of specific genes in embryo patterning by comparing pattern formation in embryos from wild-type plants and embryo-lethal mutants. Therefore, the method can be used to characterize embryogenesis in Arabidopsis.

A Method for Characterizing Embryogenesis in Arabidopsis

This protocol outlines a method for observing embryogenesis in Arabidopsis via ovule clearance followed by the inspection of embryo pattern formation under a microscope.

Given the highly predictable nature of their development, Arabidopsis embryos have been used as a model for studies of morphogenesis in plants. However, ...

Evaluation of Injury-induced Senescence and In Vivo Reprogramming in the Skeletal Muscle

Cellular senescence is a stress response that is characterized by a stable cellular growth arrest, which is important for many physiological and pathological processes, such as cancer and ageing. Recently, senescence has also been implicated in tissue repair and regeneration. Therefore, it has become increasingly critical to identify senescent cells in vivo. Senescence-associated &#946;-galactosidase (SA-&#946;-Gal) assay is the most widely used assay to detect senescent cells both in culture and in vivo. This assay is based on the increased lysosomal contents in the senescent cells, which allows the histochemical detection of lysosomal &#946;-galactosidase activity at suboptimum pH (6 or 5.5). In comparison with other assays, such as flow cytometry, this allows the identification of senescent cells in their resident environment, which offers valuable information such as the location relating to the tissue architecture, the morphology, and the possibility of coupling with other markers via immunohistochemistry&#160;(IHC). The major limitation of the SA-&#946;-Gal assay is the requirement of fresh or frozen samples.
Here, we present a detailed protocol to understand how cellular senescence promotes cellular plasticity and tissue regeneration in vivo. We use SA-&#946;-Gal to detect senescent cells in the skeletal muscle upon injury, which is a well-established system to study tissue regeneration. Moreover, we use&#160;IHC to detect Nanog, a marker of pluripotent stem cells, in a transgenic mouse model. This protocol enables us to examine and quantify cellular senescence in the context of induced cellular plasticity and in vivo reprogramming.

Evaluation of Injury-induced Senescence and In Vivo Reprogramming in the Skeletal Muscle

Here we present a detailed protocol to detect both senescent and pluripotent stem cells in the skeletal muscle upon injury while inducing in vivo reprogramming. This method is suitable for evaluating the role of cellular senescence during tissue regeneration and reprogramming in vivo.

Cellular senescence is a stress response that is characterized by a stable cellular growth arrest, which is important for many physiological and ...

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

Notch signaling is an evolutionarily conserved cell-cell communication system used broadly in animal development and adult maintenance. Interaction of the Notch receptor with ligands from neighboring cells induces activation of the signaling pathway (trans-activation), while interaction with ligands from the same cell inhibits signaling (cis-inhibition). Proper balance between trans-activation and cis-inhibition helps establish optimal levels of Notch signaling in some contexts during animal development. Because of the overlapping expression domains of Notch and its ligands in many cell types and the existence of feedback mechanisms, studying the effects of a given post-translational modification on trans- versus cis-interactions of Notch and its ligands in vivo is difficult. Here, we describe a protocol for using Drosophila S2 cells in cell-aggregation assays to assess the effects of knocking down a Notch pathway modifier on the binding of Notch to each ligand in trans and in cis. S2 cells stably or transiently transfected with a Notch-expressing vector are mixed with cells expressing each Notch ligand (S2-Delta or S2-Serrate). Trans-binding between the receptor and ligands results in the formation of heterotypic cell aggregates and is measured in terms of the number of aggregates per mL composed of &#62;6 cells. To examine the inhibitory effect of cis-ligands, S2 cells co-expressing Notch and each ligand are mixed with S2-Delta or S2-Serrate cells and the number of aggregates is quantified as described above. The relative decrease in the number of aggregates due to the presence of cis-ligands provides a measure of cis-ligand-mediated inhibition of trans-binding. These straightforward assays can provide semi-quantitative data on the effects of genetic or pharmacological manipulations on the binding of Notch to its ligands, and can help deciphering the molecular mechanisms underlying the in vivo effects of such manipulations on Notch signaling.

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

Complexity of in vivo systems makes it difficult to distinguish between the activation and inhibition of Notch receptor by trans- and cis-ligands, respectively. Here, we present a protocol based on in vitro cell-aggregation assays for qualitative and semi-quantitative evaluation of the binding of Drosophila Notch to trans-ligands vs cis-ligands.

Notch signaling is an evolutionarily conserved cell-cell communication system used broadly in animal development and adult maintenance. Interaction of the ...

Real-time Measurement of Epithelial Barrier Permeability in Human Intestinal Organoids

Advances in 3D culture of intestinal tissues obtained through biopsy or generated from pluripotent stem cells via directed differentiation, have resulted in sophisticated in vitro models of the intestinal mucosa. Leveraging these emerging model systems will require adaptation of tools and techniques developed for 2D culture systems and animals. Here, we describe a technique for measuring epithelial barrier permeability in human intestinal organoids in real-time. This is accomplished by microinjection of fluorescently-labeled dextran and imaging on an inverted microscope fitted with epifluorescent filters. Real-time measurement of the barrier permeability in intestinal organoids facilitates the generation of high-resolution temporal data in human intestinal epithelial tissue, although this technique can also be applied to fixed timepoint imaging approaches. This protocol is readily adaptable for the measurement of epithelial barrier permeability following exposure to pharmacologic agents, bacterial products or toxins, or live microorganisms. With minor modifications, this protocol can also serve as a general primer on microinjection of intestinal organoids and users may choose to supplement this protocol with additional or alternative downstream applications following microinjection.

This protocol describes the measurement of epithelial barrier permeability in real-time following pharmacologic treatment in human intestinal organoids using fluorescent microscopy and live cell microscopy.

Advances in 3D culture of intestinal tissues obtained through biopsy or generated from pluripotent stem cells via directed differentiation, have resulted ...

Induction and Validation of Cellular Senescence in Primary Human Cells

Cellular senescence is a state of permanent cell cycle arrest activated in response to different damaging stimuli. Activation of cellular senescence is a hallmark of various pathophysiological conditions including tumor suppression, tissue remodeling and aging. The inducers of cellular senescence in vivo are still poorly characterized. However, a number of stimuli can be used to promote cellular senescence ex vivo. Among them, most common senescence-inducers are replicative exhaustion, ionizing and non-ionizing radiation, genotoxic drugs, oxidative stress, and demethylating and acetylating agents. Here, we will provide detailed instructions on how to use these stimuli to induce fibroblasts into senescence. This protocol can easily be adapted for different types of primary cells and cell lines, including cancer cells. We also describe different methods for the validation of senescence induction. In particular, we focus on measuring the activity of the lysosomal enzyme Senescence-Associated &#946;-galactosidase (SA-&#946;-gal), the rate of DNA synthesis using 5-ethynyl-2&#39;-deoxyuridine (EdU) incorporation assay, the levels of expression of the cell cycle inhibitors p16 and p21, and the expression and secretion of members of the Senescence-Associated Secretory Phenotype (SASP). Finally, we provide example results and discuss further applications of these protocols.

Here, we discuss a series of protocols for induction and validation of cellular senescence in cultured cells. We focus on different senescence-inducing stimuli and describe the quantification of common senescence-associated markers. We provide technical details using fibroblasts as a model, but the protocols can be adapted to various cellular models.

Cellular senescence is a state of permanent cell cycle arrest activated in response to different damaging stimuli. Activation of cellular senescence is a ...

RNA-based Reprogramming of Human Primary Fibroblasts into Induced Pluripotent Stem Cells

Induced pluripotent stem cells (iPSCs) have proven to be a valuable tool to study human development and disease. Further advancing iPSCs as a regenerative therapeutic requires a safe, robust, and expedient reprogramming protocol. Here, we present a clinically relevant, step-by-step protocol for the extremely high-efficiency reprogramming of human dermal fibroblasts into iPSCs using a non-integrating approach. The core of the protocol consists of expressing pluripotency factors (SOX2, KLF4, cMYC, LIN28A, NANOG, OCT4-MyoD fusion) from in vitro transcribed messenger RNAs synthesized with modified nucleotides (modified mRNAs). The reprogramming modified mRNAs are transfected into primary fibroblasts every 48 h together with mature embryonic stem cell-specific microRNA-367/302 mimics for two weeks. The resulting iPSC colonies can then be isolated and directly expanded in feeder-free conditions. To maximize efficiency and consistency of our reprogramming protocol across fibroblast samples, we have optimized various parameters including the RNA transfection regimen, timing of transfections, culture conditions, and seeding densities. Importantly, our method generates high-quality iPSCs from most fibroblast sources, including difficult-to-reprogram diseased, aged, and/or senescent samples.

Here we describe a clinically relevant, high-efficiency, feeder-free method to reprogram human primary fibroblasts into induced pluripotent stem cells using modified mRNAs encoding reprogramming factors and mature microRNA-367/302 mimics. Also included are methods to assess reprogramming efficiency, expand clonal iPSC colonies, and confirm expression of the pluripotency marker TRA-1-60.

Induced pluripotent stem cells (iPSCs) have proven to be a valuable tool to study human development and disease. Further advancing iPSCs as a regenerative ...