Name: gap junctional intercellular communication: a functional biomarker to assess adverse effects of toxicants and toxins, and health benefits of natural products
Uploaded: 2016-12-25T13:00:00
Description: Watch this Scientific Journal Video about Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products

Supported by NIEHS grants #R01 ES013268-01A2, and the contents are solely the responsibility of the author and do not necessarily represent the official views of the NIEHS, and supported by CETOCOEN UPgrade project No. CZ.1.05/2.1.00/19.0382.

The protocol for this study was approved by the Animal Care and Utilization Committee of the National Institutes of Health Sciences of Japan, which is where the in vivo experiments were done, to assure that the rats were treated humanely and with regard for alleviation of suffering.
1. SL-DT Bioassay
<ol>
	<li>Seed 3 x 105 WB-F344 rat liver epithelial cells onto 35 mm diameter culture plates containing Eagles modified medium plus 5% fetal bovine serum, and culture the cells in an incubator at...

<ol>
	<li>Rotroff, D. 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=Predictive+endocrine+testing+in+the+21st+century+using+in+vitro+assays+of+estrogen+receptor+signaling+responses.">Predictive endocrine testing in the 21st century using in vitro assays of estrogen receptor signaling responses.</a> Environ.Sci.Technol. 48 (15), 8706-8716 (2014).</li><li>Axelsen, L. N., Calloe, K., Holstein-Rathlou, N. H., Nielsen, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Managing+the+complexity+of+communication:+regulation+of+gap+junctions+by+post-translational+modification.">Managing the complexity of communication: regulation of gap junctions by post-translational modification.</a> Front Pharmacol. 4, 130 (2013).</li><li>Nielsen, M. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gap+junctions.">Gap junctions.</a> Compr.Physiol. 2 (3), 1981-2035 (2012).</li><li>Sovadinova, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phosphatidylcholine+specific+PLC-induced+dysregulation+of+gap+junctions,+a+robust+cellular+response+to+environmental+toxicants,+and+prevention+by+resveratrol+in+a+rat+liver+cell+model.">Phosphatidylcholine specific PLC-induced dysregulation of gap junctions, a robust cellular response to environmental toxicants, and prevention by resveratrol in a rat liver cell model.</a> PLoS.One. 10 (5), e0124454 (2015).</li><li>Trosko, J. E., Chang, C. C., Travis, C. 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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+integrative+signaling+through+gap+junctions+in+toxicology.">Role of integrative signaling through gap junctions in toxicology.</a> Curr.Protoc.Toxicol. 47, 2.18:2.18.1-2.18:2.18.18 (2011).</li><li>Vinken, 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=Connexins+and+their+channels+in+cell+growth+and+cell+death.">Connexins and their channels in cell growth and cell death.</a> Cell.Signal. 18 (5), 592-600 (2006).</li><li>Browne, C. L., Wiley, H. S., Dumont, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oocyte-follicle+cell+gap+junctions+in+Xenopus+laevis+and+the+effects+of+gonadotropin+on+their+permeability.">Oocyte-follicle cell gap junctions in Xenopus laevis and the effects of gonadotropin on their permeability.</a> Science. 203 (4376), 182-183 (1979).</li><li>El-Fouly, M. H., Trosko, J. E., Chang, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scrape-loading+and+dye+transfer.+A+rapid+and+simple+technique+to+study+gap+junctional+intercellular+communication.">Scrape-loading and dye transfer. A rapid and simple technique to study gap junctional intercellular communication.</a> Exp.Cell Res. 168 (2), 422-430 (1987).</li><li>Wade, M. H., Trosko, J. E., Schindler, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+fluorescence+photobleaching+assay+of+gap+junction-mediated+communication+between+human+cells.">A fluorescence photobleaching assay of gap junction-mediated communication between human cells.</a> Science. 232 (4749), 525-528 (1986).</li><li>Upham, B. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure-activity-dependent+regulation+of+cell+communication+by+perfluorinated+fatty+acids+using+in+vivo+and+in+vitro+model+systems.">Structure-activity-dependent regulation of cell communication by perfluorinated fatty acids using in vivo and in vitro model systems.</a> Environ. Health Perspect. 117 (4), 545-551 (2009).</li><li>Trosko, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gap+junctional+intercellular+communication+as+a+biological+&amp;#34;Rosetta+stone&amp;#34;+in+understanding,+in+a+systems+biological+manner,+stem+cell+behavior,+mechanisms+of+epigenetic+toxicology,+chemoprevention+and+chemotherapy.">Gap junctional intercellular communication as a biological &amp;#34;Rosetta stone&amp;#34; in understanding, in a systems biological manner, stem cell behavior, mechanisms of epigenetic toxicology, chemoprevention and chemotherapy.</a> J. Membr. Biol. 218 (1-3), 93-100 (2007).</li><li>Upham, B. L., Weis, L. M., Trosko, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulated+gap+junctional+intercellular+communication+as+a+biomarker+of+PAH+epigenetic+toxicity:+structure-function+relationship.">Modulated gap junctional intercellular communication as a biomarker of PAH epigenetic toxicity: structure-function relationship.</a> Environ.Health Perspect. 106, 975-981 (1998).</li><li>Upham, B. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tumor+promoting+properties+of+a+cigarette+smoke+prevalent+polycyclic+aromatic+hydrocarbon+as+indicated+by+the+inhibition+of+gap+junctional+intercellular+communication+via+phosphatidylcholine-specific+phospholipase.">Tumor promoting properties of a cigarette smoke prevalent polycyclic aromatic hydrocarbon as indicated by the inhibition of gap junctional intercellular communication via phosphatidylcholine-specific phospholipase.</a> C. Cancer Sci. 99 (4), 696-705 (2008).</li><li>Sai, K., Kanno, J., Hasegawa, R., Trosko, J. E., Inoue, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevention+of+the+down-regulation+of+gap+junctional+intercellular+communication+by+green+tea+in+the+liver+of+mice+fed+pentachlorophenol.">Prevention of the down-regulation of gap junctional intercellular communication by green tea in the liver of mice fed pentachlorophenol.</a> Carcinogenesis. 21 (9), 1671-1676 (2000).</li><li>Upham, B. L., Deocampo, N. D., Wurl, B., Trosko, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+gap+junctional+intercellular+communication+by+perfluorinated+fatty+acids+is+dependent+on+the+chain+length+of+the+fluorinated+tail.">Inhibition of gap junctional intercellular communication by perfluorinated fatty acids is dependent on the chain length of the fluorinated tail.</a> Int. J. Cancer. 78 (4), 491-495 (1998).</li><li>Trosko, J. E., Tai, M. H., Dittmar, T., Zaenkar, K. S., Schmidt, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infections+and+inflammation:+Impacts+on+oncogenesis.+Impacts+on+Oncogenesis.">Infections and inflammation: Impacts on oncogenesis. Impacts on Oncogenesis.</a> Contrib Microbiol. , 45-65 (2006).</li><li>Trosko, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+stem+cells+as+targets+for+the+aging+and+diseases+of+aging+processes.">Human stem cells as targets for the aging and diseases of aging processes.</a> Med. Hypotheses. 60 (3), 439-447 (2003).</li><li>JE, T. r. o. s. k. o., Dittmar, T., Zaenkar, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Stem Cells and Cancer. , 147-188 (2008).</li><li>Osgood, R. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polycyclic+aromatic+hydrocarbon-induced+signaling+events+relevant+to+inflammation+and+tumorigenesis+in+lung+cells+are+dependent+on+molecular+structure.">Polycyclic aromatic hydrocarbon-induced signaling events relevant to inflammation and tumorigenesis in lung cells are dependent on molecular structure.</a> PLoS. One. 8 (6), e65150 (2014).</li><li>Weis, L. M., Rummel, A. M., Masten, S. J., Trosko, J. E., Upham, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bay+or+baylike+regions+of+polycyclic+aromatic+hydrocarbons+were+potent+inhibitors+of+gap+junctional+intercellular+communication.">Bay or baylike regions of polycyclic aromatic hydrocarbons were potent inhibitors of gap junctional intercellular communication.</a> Environ.Health Perspect. 106 (1), 17-22 (1998).</li><li>Yotti, L. P., Chang, C. C., Trosko, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elimination+of+metabolic+cooperation+in+Chinese+hamster+cells+by+a+tumor+promoter.">Elimination of metabolic cooperation in Chinese hamster cells by a tumor promoter.</a> Science. 206 (4422), 1089-1091 (1979).</li><li>Zhao, 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=New+caged+coumarin+fluorophores+with+extraordinary+uncaging+cross+sections+suitable+for+biological+imaging+applications.">New caged coumarin fluorophores with extraordinary uncaging cross sections suitable for biological imaging applications.</a> J. Am. Chem. Soc. 126 (14), 4653-4663 (2004).</li><li>Goldberg, G. S., Bechberger, J. F., Naus, C. 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The SL-DT assay is a simple and versatile technique in measuring GJIC, but there are several critical concerns that should be accounted for in designing appropriate experimental protocols. For robust measurements of GJIC using the SL-DT assay there must be a good dye spread of the LY through gap junctions of the cells. At minimum, an adequate time should be selected to assure that the dye spreads through eight or more rows of cells from the scalpel loaded cells in both directions. Also, for the ease of measurement of the...

The overall goal of this method is to provide a simple, comprehensive and relatively inexpensive technique to assess the potential toxicities of compounds. This is an in vitro approach that can be used in multiple cell lines. Standard cell biology labs equipped with epifluorescence microscopes can conduct research using this assay.
Our basic knowledge of cell functions has been highly dependent on in vitro bioassays, and has become an essential component in toxicological assessments of pharmaceuticals, environmental pollutants, and food born contaminants. Unfortunately, there is no single in vitro bioassay system that can comprehensively meet the demands for all toxicological assessments. Many in vitro assays are designed and optimized to evaluate as well as assess a specific biochemical or molecular endpoint. These are quite often combined in a high throughput set up to reflect a perturbation of a certain signal transduction pathway, such as estrogen-receptor signaling1. This strategy has been quite successful, but the extensive number of signal transduction pathways involved in gene expression makes the task of choosing a specific signaling pathway to assess quite complex. High through-put protocols are currently being developed and used to simultaneously measure numerous signaling pathways, which has been one approach to overcome some of the limitations of single assays. However, not all signaling pathways have been successfully incorporated into more comprehensive approaches, plus new signaling pathways are constantly being discovered that further complicates this assessment process. Using extensive numbers of in vitro approaches, particularly high through-put systems, for comprehensive toxicological assessments are also very expensive and are not conducive to most single investigator led research projects.
GJIC is a process tightly controlled by changes in voltage, calcium concentration, pH, redox balance, regulated by major intracellular signal transduction pathways and interactions with membrane and cytoskeleton proteins2,3. Thus, inhibition of GJIC can reflect different types of cellular stress, disruption of different cellular functions, or perturbations of different signal transduction pathways. Another approach to overcome the use of limited signal transduction bioassays is to take advantage of the biological phenomena that many, if not most, signal transduction pathways are further modulated by cooperative intercellular signaling systems through gap junction channels4-8. Although intercellular signaling systems are also numerous and under multiple pathway control, the intercellular signaling through gap junction channels is ultimately a function of the channels being opened, partially closed or completely closed. This provides an endpoint that can be easily measured using various in vitro bioassay systems7. Considering that the homeostatic set point of a tissue requires open channels, determining the effect of compounds on gap junctional intercellular communication (GJIC) is a more comprehensive approach in determining potential toxic effects of compounds4,8. In essence, this critical biological phenomenon that plays a central role in coordinating multiple signal transduction events controlling gene expression allows for a broad assessment of toxic effects. Thus, bioassays that assess GJIC are an excellent starting point to evaluate the toxic potential of compounds.
The most extensive techniques used to assess GJIC are based on preloading cells with a fluorescent probe and then monitoring the migration of the dye from the loaded cell or cells to adjacent cells. Techniques to preload the dye have involved microinjection9, scrape loading10, and methyl esters of the probes11. The scalpel loading-fluorescent dye transfer (SL-DT) method is a modification of the scrape load - dye transfer assay developed by El Fouly10. Rather than the more invasive scrape, the scalpel loading method of this report involves a gentle roll of a scalpel with a round blade through a monolayer of cells that minimize invasive damage (Figure 1). The advantages of this technique are the toxicological assessment of a population of cells rather than single cells of the microinjection assay. Furthermore, the simplicity of this assay allows for rapid detection of multiple plates in a short time whereas methods using microinjection techniques and techniques that use methyl esters of fluorescent probes are significantly more time consuming and require considerably higher skill level.
Although there is no single method to meet all the needs of studying GJIC; the SL-DT assay is a simple, fairly inexpensive and versatile assay that can meet many of the needs for initial assessments of toxicities of various compounds. Major advantages include: simplicity, no special need for equipment or skills that are required for other methods such as microinjection, fluorescent recovery after photobleaching (FRAP) assay and local activation of molecular fluorescent probe assays, a rapid and simultaneous assessment of GJIC in a large number of cells, conducive to a high throughput set-up with automated fluorescence microscopy imaging and analysis, as well as its adaptability for in vivo studies.

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			<td height="63" style="height:63px;width:312px;">WB-F344 rat liver epithelial cells</td>
			<td style="width:217px;">From Drs. J. W. Grisham and M. S. Tsao of the University of North Carolina (Chapel Hill, NC)</td>
			<td style="width:279px;">none</td>
			<td style="width:431px;">Provided by Drs. J. W. Grisham and M. S. Tsao University of North Carolina-Chapel Hill-NC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">35 mm Culture Plates</td>
			<td style="width:217px;">Corning</td>
			<td style="width:279px;">430165</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">25 cm2 culture flasks</td>
			<td style="width:217px;">Corning</td>
			<td style="width:279px;">430639</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">75 cm2 culture flasks</td>
			<td style="width:217px;">Corning</td>
			<td style="width:279px;">430641</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">D-medium, an Eagles modified medium&#160;</td>
			<td style="width:217px;">ThermoFisher/GIBCO&#160;</td>
			<td style="width:279px;">Formula No. 78-5470EF</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">fetal bovine serum</td>
			<td style="width:217px;">ThermoFisher/GIBCO&#160;</td>
			<td style="width:279px;">10437</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.25% trypsin-EDTA&#160;</td>
			<td style="width:217px;">ThermoFisher/GIBCO&#160;</td>
			<td style="width:279px;">15050</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:312px;">phosphate buffered saline</td>
			<td style="width:217px;">homemade</td>
			<td style="width:279px;">see below for ingredient cat#&#39;s</td>
			<td>137 mM NaCl, 2.7 mM KCl, 10 mM Na2PO4, 2 mM KH2PO4</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">KCl</td>
			<td style="width:217px;">JT Baker - Mallinckrodt&#160;</td>
			<td style="width:279px;">3040-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">NaCl</td>
			<td style="width:217px;">JT Baker - Mallinckrodt&#160;</td>
			<td style="width:279px;">3624-05</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Na2HPO4</td>
			<td style="width:217px;">JT Baker - Mallinckrodt&#160;</td>
			<td style="width:279px;">3819--01</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">KH2PO4</td>
			<td style="width:217px;">JT Baker - Mallinckrodt&#160;</td>
			<td style="width:279px;">3246-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Lucifer Yellow CH, lithium salt</td>
			<td style="width:217px;">Sigma-Aldrich Chemical</td>
			<td style="width:279px;">L0259</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">rhodamine-dextran</td>
			<td style="width:217px;">Sigma-Aldrich Chemical</td>
			<td style="width:279px;">R9379</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">1-methylanthracene</td>
			<td style="width:217px;">Sigma-Aldrich Chemical</td>
			<td style="width:279px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">phenanthrene</td>
			<td style="width:217px;">Sigma-Aldrich Chemical</td>
			<td style="width:279px;">P11409</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">resveratrol</td>
			<td style="width:217px;">Sigma-Aldrich Chemical</td>
			<td style="width:279px;">R5010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">D609</td>
			<td>Tocris Bioscience&#160;</td>
			<td style="width:279px;">1437</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">acetonitril</td>
			<td>EMD</td>
			<td style="width:279px;">AX0145-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">37% solution formaldehyde</td>
			<td>JT Baker - Mallinckrodt&#160;</td>
			<td style="width:279px;">2106-01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">#20 surgical blade</td>
			<td>Fine Science Tools Inc.&#160;</td>
			<td>10317-14</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">50 mL conical sterile tubes</td>
			<td>Thermo scientific&#160;</td>
			<td>339652</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nikon epifluorescence microscope&#160;</td>
			<td style="width:217px;">Nikon -Mager Scientific</td>
			<td style="width:279px;">Eclipse TE300</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nikon FITC dichroic cube</td>
			<td style="width:217px;">Nikon -Mager Scientific</td>
			<td style="width:279px;">96107</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#160;CCD camera&#160;</td>
			<td style="width:217px;">Nikon -Mager Scientific</td>
			<td style="width:279px;">Nikon Cool Snap EZ CCD</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#160;imaging system.</td>
			<td style="width:217px;">Nikon -Mager Scientific</td>
			<td>Nikon NIS-Elements F2.2 imaging system.</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:312px;">Image J</td>
			<td style="width:217px;">National Institute of Health</td>
			<td style="width:279px;">http://imagej.nih.gov/ij/</td>
			<td></td>
		</tr>
	</tbody>
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gap junctional intercellular communication: a functional biomarker to assess adverse effects of toxicants and toxins, and health benefits of natural products

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction channels, which is a major intercellular process by which tissue homeostasis is maintained. Interruption of gap junctional intercellular communication (GJIC) by toxicants, toxins, drugs, etc. has been linked to numerous adverse health effects. Many genetic-based human diseases have been linked to mutations in gap junction genes. The SL-DT technique is a simple functional assay for the simultaneous assessment of GJIC in a large population of cells. The assay involves pre-loading cells with a fluorescent dye by briefly perturbing the cell membrane with a scalpel blade through a population of cells. The fluorescent dye is then allowed to traverse through gap junction channels to neighboring cells for a designated time. The assay is then terminated by the addition of formalin to the cells. The spread of the fluorescent dye through a population of cells is assessed with an epifluorescence microscope and the images are analyzed with any number of morphometric software packages that are available, including free software packages found on the public domain. This assay has also been adapted for in vivo studies using tissue slices from various organs from treated animals. Overall, the SL-DT assay can serve a broad range of in vitro pharmacological and toxicological needs, and can be potentially adapted for high throughput set-up systems with automated fluorescence microscopy imaging and analysis to elucidate more samples in a shorter time.

Interruption of GJIC has been extensively used as a biomarker for identifying toxic compounds at the nongenotoxic, epigenetic level of gene control that induces adverse health effects14. For example, polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants of the environment but vary in their epigenetic toxicities as a function of their molecular structures15. The lower molecular weight PAHs are typically found at relatively higher concentrations than the ...

Watch this Scientific Journal Video about Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products 

Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products

This protocol describes a scalpel loading-fluorescent dye transfer technique that measures intercellular communication through gap junction channels. Gap junctional intercellular communication is a major cellular process by which tissue homeostasis is maintained and disruption of this cell signaling has adverse health effects.

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction ...

The overall goal is to provide a simple assay to measure gap junctional intercellular communication through a population of mammalian cells that can serve a broad range of in vitro pharmacological and toxicological needs. This method can help answer key questions in the toxicology field, such as whether a compound affects the development or maintenance of a tissue, by disregulating gap junctional intercellular communication. The main advantage of this technique is that it offers a simple and quick assessment of gap junction function in a large population of cells in response to toxicants and toxins.Demonstrating the procedure will be Ajna Uzuni, an undergraduate research assistant from my laboratory. To begin the experiment, seed three times 10 to the fifth WB-F344 rat liver epithelial cells onto 35 millimeter diameter culture plates containing Eagle's modified medium plus 5%fetal-bovine serum. Culture the cells in an incubator until they reach 100%confluence and continue with the experimental treatment of the cells.To continue with dose-response experiments, add 10 microliters and 20 microliters of a previously prepared, two millimolar stock solution of phenanthrene in 100%acetonitrile, and four microliters, six microliters, and eight microliters of a 20 millimolar stock solution of phenanthrene in 100%acetonitrile to three plates of cells containing two milliliters of growth medium for each added volume of stock solution. Next, add four microliters, six microliters, eight microliters, 10 microliters, and 20 microliters of a 100%solution of acetonitrile to three plates of cells containing two milliliters of growth medium for each added volume of acetonitrile solution to serve as the vehicle control. After adding the acetonitrile, incubate the plates.To perform time response experiments, add seven microliters of a 20 millimolar stock solution of phenanthrene in 100%acetonitrile to three plates of cells, containing two milliliters of growth medium for each time point. Then, add seven microliters of 100%acetonitrile to three plates of cells, containing two milliliters of growth medium for each time point, to serve as the vehicle control. Incubate the plates for each designated time point.Discard the culture medium by gently pouring off the medium. Rinse the cells with three milliliters of PBS, and either decant or aspirate between rinses. Pipette one milliliter of one milligram per milliliter lucifer yellow dye dissolved in PBS into each cell plate.Preload the dye into the cells by pinching the scalpel between the index finger and thumb. Place the scalpel perpendicular to and five millimeters from the edge of the culture plate and then use gravity to allow the scalpel to gently roll from this perpendicular angle to an angle of 15 degrees. Roll the blade through a population of cells in three different areas of the total plate.Next, incubate the cells with the LY solution for three minutes at room temperature. Decant or aspirate the LY and rinse the cells to remove all extracellular dye and eliminate extra cellular background fluorescence. Then, add 0.5 milliliters of a 4%phosphate buffered formalin solution to fix the cells.View the fixed cells using an epifluorescence microscope at 200x magnification. Align all of the plates so that the indentation line is parallel to the horizontal field of vision. A series of SL-DT images were generated of WB-F344 rat liver epithelial cells treated with increasing doses of phenanthrene.The decrease in lucifer yellow fluorescent dye migration is caused by increasing doses of phenanthrene, demonstrating the increasing toxicant-induced inhibition of gap junctional intercellular communication, or GJIC. The fraction of the control, or FOC values, obtained from the SL-DT images were averaged, statistically analysed, and then graphed. Following this procedure, other methods like western blots of single transduction proteins can be performed in order to answer additional questions.Like, are these compounds activating mitogenic events of cell perforation?

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Unit 1

Cell-Cell Interactions

SCIENTISTS IN ACTION

Using Unfixed, Frozen Tissues to Study Natural Mucin Distribution

Mucins are complex and heavily glycosylated O-linked glycoproteins, which contain more than 70% carbohydrate by weight1-3. Secreted mucins, produced by goblet cells and the gastric mucosa, provide the scaffold for a micrometers-thick mucus layer that lines the epithelia of the gut and respiratory tract3,4. In addition to mucins, mucus layers also contain antimicrobial peptides, cytokines, and immunoglobulins5-9. The mucus layer is an important part of host innate immunity, and forms the first line of defense against invading microorganisms8,10-12. As such, the mucus is subject to numerous interactions with microbes, both pathogens and symbionts, and secreted mucins form an important interface for these interactions. The study of such biological interactions usually involves histological methods for tissue collection and staining. The two most commonly used histological methods for tissue collection and preservation in the clinic and in research laboratories are: formalin fixation followed by paraffin embedding, and tissue freezing, followed by embedding in cryo-protectant media.
Paraffin-embedded tissue samples produce sections with optimal qualities for histological visualization including clarity and well-defined morphology. However, during the paraffin embedding process a number of epitopes become altered and in order to study these epitopes, tissue sections have to be further processed with one of many epitope retrieval methods13. Secreted mucins and lipids are extracted from the tissue during the paraffin-embedding clearing step, which requires prolong incubation with organic solvents (xylene or Citrisolv). Therefore this approach is sub-optimal for studies focusing on the nature and distribution of mucins and mucus in vivo.
In contrast, freezing tissues in Optimal Cutting Temperature (OCT) embedding medium avoids dehydration and clearing of the sample, and maintains the sample hydration. This allows for better preservation of the hydrated mucus layer, and thus permits the study of the numerous roles of mucins in epithelial biology. As this method requires minimal processing of the tissue, the tissue is preserved in a more natural state. Therefore frozen tissues sections do not require any additional processing prior to staining and can be readily analyzed using immunohistochemistry methods.
We demonstrate the preservation of micrometers-thick secreted mucus layer in frozen colon samples. This layer is drastically reduced when the same tissues are embedded in paraffin. We also demonstrate immunofluorescence staining of glycan epitopes presented on mucins using plant lectins. The advantage of this approach is that it does not require the use of special fixatives and allows utilizing frozen tissues that may already be preserved in the laboratory.

Unfixed frozen tissue samples embedded in Optimal Cutting Temperature medium (OCT) can be used to study natural distribution and glycosylation of secreted mucus. In this approach tissue processing is minimal and the natural presentation of glycolipids, mucins and glycan-epitopes is preserved. Tissue sections can be analyzed by immunohistochemistry using fluorescence or chromogenic detection.

Mucins are complex and heavily glycosylated O-linked glycoproteins, which contain more than 70% carbohydrate by weight1-3. Secreted mucins, produced by ...

A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide

In this technique, cells are cultured on a glass slide that is partly coated with indium-tin oxide (ITO), a transparent, electrically conductive material. A variety of molecules, such as peptides or oligonucleotides can be introduced into essentially 100% of the cells in a non-traumatic manner.&#160; Here, we describe how it can be used to study intercellular, gap junctional communication. Lucifer yellow penetrates into the cells when an electric pulse, applied to the conductive surface on which they are growing, causes pores to form through the cell membrane. This is electroporation. Cells growing on the nonconductive&#160;glass surface immediately adjacent to the electroporated region do not take up Lucifer yellow by electroporation but do acquire the fluorescent dye as it is passed to them via gap junctions that link them to the electroporated cells. The results of the transfer of dye from cell to cell can be observed microscopically under fluorescence illumination. This technique allows for precise quantitation of gap junctional communication. In addition, it can be used for the introduction of peptides or other non-permeant molecules, and the transfer of small electroporated peptides via gap junctions to inhibit the signal in the adjacent, non-electroporated cells is a powerful demonstration of signal inhibition.

This presentation demonstrates a method whereby electroporation of adherent, cultured cells is used for the study of intercellular, junctional communication, while the cells grow on a slide coated with conductive and transparent indium-tin oxide.

In this technique, cells are cultured on a glass slide that is partly coated with indium-tin oxide (ITO), a transparent, electrically conductive material. ...

Use of MALDI-TOF Mass Spectrometry and a Custom Database to Characterize Bacteria Indigenous to a Unique Cave Environment (Kartchner Caverns, AZ, USA)

MALDI-TOF mass spectrometry has been shown to be a rapid and reliable tool for identification of bacteria at the genus and species, and in some cases, strain levels. Commercially available and open source software tools have been developed to facilitate identification; however, no universal/standardized data analysis pipeline has been described in the literature. Here, we provide a comprehensive and detailed demonstration of bacterial identification procedures using a MALDI-TOF mass spectrometer. Mass spectra were collected from 15 diverse bacteria isolated from Kartchner Caverns, AZ, USA, and identified by 16S rDNA sequencing. Databases were constructed in BioNumerics 7.1. Follow-up analyses of mass spectra were performed, including cluster analyses, peak matching, and statistical analyses. Identification was performed using blind-coded samples randomly selected from these 15 bacteria. Two identification methods are presented: similarity coefficient-based and biomarker-based methods. Results show that both identification methods can identify the bacteria to the species level.

Use of MALDI-TOF Mass Spectrometry and a Custom Database to Characterize Bacteria Indigenous to a Unique Cave Environment Kartchner Caverns, AZ, USA

This work details procedures for rapid identification of bacteria using MALDI-TOF MS. The identification procedures include spectrum acquisition, database construction, and follow up analyses. Two identification methods, similarity coefficient-based and biomarker-based methods, are presented.

MALDI-TOF mass spectrometry has been shown to be a rapid and reliable tool for identification of bacteria at the genus and species, and in some cases, ...

Quantitation of Endothelial Cell Adhesiveness In Vitro

One of the cardinal processes of inflammation is the infiltration of immune cells from the lumen of the blood vessel to the surrounding tissue. This occurs when endothelial cells, which line blood vessels, become adhesive to circulating immune cells such as monocytes. In vitro measurement of this adhesiveness has until now been done by quantifying the total number of monocytes that adhere to an endothelial layer either as a direct count or by indirect measurement of the fluorescence of adherent monocytes. While such measurements do indicate the average adhesiveness of the endothelial cell population, they are confounded by a number of factors, such as cell number, and do not reveal the proportion of endothelial cells that are actually adhesive. Here we describe and demonstrate a method which allows the enumeration of adhesive cells within a tested population of endothelial monolayer. Endothelial cells are grown on glass coverslips and following desired treatment are challenged with monocytes (that may be fluorescently labeled). After incubation, a rinsing procedure, involving multiple rounds of immersion and draining, the cells are fixed. Adhesive endothelial cells, which are surrounded by monocytes are readily identified and enumerated, giving an adhesion index that reveals the actual proportion of endothelial cells within the population that are adhesive.

Quantitation of Endothelial Cell Adhesiveness In Vitro

We report an in vitro method that allows the quantitation of the actual number of adhesive cells within an endothelial cell monolayer.

One of the cardinal processes of inflammation is the infiltration of immune cells from the lumen of the blood vessel to the surrounding tissue. This ...

Procedure and Key Optimization Strategies for an Automated Capillary Electrophoretic-based Immunoassay Method

New technologies that utilize capillary-based immunoassays promise faster and more quantitative protein assessment compared to traditional immunoassays. However, similar to other antibody-based protein assays, optimization of capillary-based immunoassay parameters, such as protein concentration, antibody dilution, and exposure time is an important prerequisite to the generation of meaningful and reliable data. Measurements must fall within the linear range of the assay where changes in signal are directly proportional to changes in lysate concentration. The process of choosing appropriate lysate concentrations, antibody dilutions, and exposure times in the human bronchial epithelial cell line, BEAS-2B, is demonstrated here. Assay linearity is shown over a range of whole cell extract protein concentrations with p53 and &#945;-tubulin antibodies. An example of signal burnout is seen at the highest concentrations with long exposure times, and an &#945;-tubulin antibody dilution curve is shown demonstrating saturation. In addition, example experimental results are reported for doxorubicin-treated cells using optimized parameters.

A capillary-based immunoassay using a commercial platform to measure target proteins from total protein preparations is demonstrated. In addition, assay parameters of exposure time, protein concentration, and antibody dilution are optimized for a cell culture model system.

New technologies that utilize capillary-based immunoassays promise faster and more quantitative protein assessment compared to traditional immunoassays. ...

A Method to Assess Bacteriocin Effects on the Gut Microbiota of Mice

Very intriguing questions arise with our advancing knowledge on gut microbiota composition and the relationship with health, particularly relating to the factors that contribute to maintaining the population balance. However, there are limited available methodologies to evaluate these factors. Bacteriocins are antimicrobial peptides produced by many bacteria that may confer a competitive advantage for food acquisition and/or niche establishment. Many probiotic lactic acid bacteria (LAB) strains have great potential to promote human and animal health by preventing the growth of pathogens. They can also be used for immuno-modulation, as they produce bacteriocins. However, the antagonistic activity of bacteriocins is normally determined by laboratory bioassays under well-defined but over-simplified conditions compared to the complex gut environment in humans and animals, where bacteria face multifactorial influences from the host and hundreds of microbial species sharing the same niche. This work describes a complete and efficient procedure to assess the effect of a variety of bacteriocins with different target specificities in a murine system. Changes in the microbiota composition during the bacteriocin treatment are monitored using compositional 16S rDNA sequencing. Our approach uses both the bacteriocin producers and their isogenic non-bacteriocin-producing mutants, the latter giving the ability to distinguish bacteriocin-related from non-bacteriocin-related modifications of the microbiota. The fecal DNA extraction and 16S rDNA sequencing methods are consistent and, together with the bioinformatics, constitute a powerful procedure to find faint changes in the bacterial profiles and to establish correlations, in terms of cholesterol and triglyceride concentration, between bacterial populations and health markers. Our protocol is generic and can thus be used to study other compounds or nutrients with the potential to alter the host microbiota composition, either when studying toxicity or beneficial effects.

Bacteriocins are believed to play a key role in defining microbial diversity in different ecological niches. Here, we describe an efficient procedure to assess how bacteriocins affect gut microbiota composition in an animal model.

Very intriguing questions arise with our advancing knowledge on gut microbiota composition and the relationship with health, particularly relating to the ...

An Iodide-Yellow Fluorescent Protein-Gap Junction-Intercellular Communication Assay

Gap junctions (GJs) are cell membrane channels that allow diffusion of molecules smaller than 1 kDa between adjacent cells. As they have physiological and pathological roles, there is need of high-throughput screening (HTS) assays to identify GJ modulators in drug discovery and toxicology assays. A novel iodide-yellow fluorescent protein-gap junction-intercellular communication (I-YFP-GJIC) assay fulfills this need. It is a cell-based assay including acceptor and donor cells that are engineered to stably express a yellow fluorescent protein (YFP) variant, whose fluorescence is sensitively quenched by iodide, or SLC26A4, an iodide transporter, respectively. When iodide is added to a mixed culture of the two cell types, they enter the donor cells via the SLC26A4 transporter and diffuse to the adjacent acceptor cells via GJs where they quench the YFP fluorescence. YFP fluorescence is measured well by well in a kinetic mode. The YFP quenching rate reflects GJ activity. The assay is reliable and rapid enough to be used for HTS. The protocol for the I-YFP-GJIC assay using the LN215 cells, human glioma cells, is described.

Here, we present a protocol for a novel gap junction intercellular communication assay designed for the high-throughput screening of gap junction-modulating chemicals for drug discovery and toxicological assessment.

Gap junctions (GJs) are cell membrane channels that allow diffusion of molecules smaller than 1 kDa between adjacent cells. As they have physiological and ...

At-Risk Butterfly Captive Propagation Programs to Enhance Life History Knowledge and Effective Ex Situ Conservation Techniques

Improving knowledge of ex situ best practices for at-risk butterflies is important for generating successful conservation and recovery program outcomes. Research on such captive populations can also yield valuable data to address key information gaps about the behavior, life history, and ecology of the target taxa. We describe a protocol for captive propagation of the federally endangered Cyclargus thomasi bethunebakeri that can be used as a model for other at-risk butterfly ex situ programs, especially those in the family Lycaenidae. We further provide a simple and straightforward protocol for recording various life history metrics that can be useful for informing ex situ methodologies as well as adapted for laboratory studies of other lepidoptera.

Here, we present protocols for 1) the laboratory captive propagation of the federally endangered Miami blue butterfly (Cyclargus thomasi bethunebakeri), and 2) assessing basic life history information such as immature development time and number of larval stadia. Both methods can be adapted for use with other ex situ conservation programs.

Improving knowledge of ex situ best practices for at-risk butterflies is important for generating successful conservation and recovery program outcomes. ...

Field Identification of Matricaria chamomilla using a Portable qPCR System

Quality control in botanical products begins with the raw material supply. Traditionally, botanical identification is performed through morphological assessment and chemical analytical methods. However, the lack of availability of botanists, especially in recent years, coupled with the need to enhance quality control to combat the stresses on the supply chain brought by increasing consumer demand and climate change, necessitates alternative approaches. The goal of this protocol is to facilitate botanical species identification using a portable qPCR system on the field or in any setting, where access to laboratory equipment and expertise is limited. Target DNA is amplified using dye-based qPCR, with DNA extracted from botanical reference materials serving as a positive control. The target DNA is identified by its specific amplification and matching its melting peak against the positive control. A detailed description of the steps and parameters, from hands-on field sample collection, to DNA extraction, PCR amplification, followed by data interpretation, has been included to ensure that readers can replicate this protocol. The results produced align with traditional laboratory botanical identification methods. The protocol is easy to perform and cost-effective, enabling quality testing on raw materials as close to the point of origin of the supply chain as possible.

Field Identification of Matricaria chamomilla using a Portable qPCR System

Presented here is a protocol for field identification of Matricaria chamomilla using a portable qPCR system. This easy-to-perform protocol is ideal as a method to confirm the identity of a botanical species at locations where access to laboratory equipment and expertise is limited, such as farms and warehouses.

Quality control in botanical products begins with the raw material supply. Traditionally, botanical identification is performed through morphological ...

Profiling of H3K4me3 Modification in Plants using Cleavage under Targets and Tagmentation

Epigenomic regulation at the chromatic level, including DNA and histone modifications, behaviors of transcription factors, and non-coding RNAs with their recruited proteins, lead to temporal and spatial control of gene expression. Cleavage under targets and tagmentation (CUT&#38;Tag) is an enzyme-tethering method in which the specific chromatin protein is firstly recognized by its specific antibody, and then the antibody tethers a protein A-transposase (pA-Tn5) fusion protein, which cleaves the targeted chromatin in situ by the activation of magnesium ions. Here, we provide our previously published CUT&#38;Tag protocol using intact nuclei isolated from allortetraploid cotton leaves with modification. This step-by-step protocol can be used for epigenomic research in plants. In addition, substantial modifications for plant nuclei isolation are provided with critical comments.

Cleavage under targets and tagmentation (CUT&amp;Tag) is an efficient chromatin epigenomic profiling strategy. This protocol presents a refined CUT&amp;Tag strategy for the profiling of histone modifications in plants.

Epigenomic regulation at the chromatic level, including DNA and histone modifications, behaviors of transcription factors, and non-coding RNAs with their ...