Name: glomerular outgrowth as an ex vivo assay to analyze pathways involved in parietal epithelial cell activation
Uploaded: 2020-08-19T13:00:00
Description: Watch this Scientific Journal Video about Glomerular Outgrowth as an Ex Vivo Assay to Analyze Pathways Involved in Parietal Epithelial Cell Activation at JoVE.com

This research was supported by Dutch Kidney foundation (grant 14A3D104) and The Netherlands Organization for Scientific Research (NWO VIDI grant: 016.156.363).

All animal experiments were performed according to the guidelines of the Animal Ethics Committee of the Radboud University Nijmegen.
NOTE: Untreated, healthy wild type (WT) mice (n = 4) and cd44-/- (n = 4) mice were sacrificed at the age of 12&#8722;16 weeks. Both male and female mice were used. All mice were on the C57Bl/6 background.
1. Mouse kidney dissection
<ol>
	<li>Sacrifice healthy WT mice or genetically altered mice by cervical dislocation.</li>
...

<ol>
	<li>Fatima, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Parietal+epithelial+cell+activation+marker+in+early+recurrence+of+FSGS+in+the+transplant.">Parietal epithelial cell activation marker in early recurrence of FSGS in the transplant.</a> Clinical journal of the American Society of Nephrology: CJASN. 7 (11), 1852-1858 (2012).</li><li>Dijkman, H. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proliferating+cells+in+HIV+and+pamidronate-associated+collapsing+focal+segmental+glomerulosclerosis+are+parietal+epithelial+cells.">Proliferating cells in HIV and pamidronate-associated collapsing focal segmental glomerulosclerosis are parietal epithelial cells.</a> Kidney International. 70 (2), 338-344 (2006).</li><li>Kuppe, 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=Common+histological+patterns+in+glomerular+epithelial+cells+in+secondary+focal+segmental+glomerulosclerosis.">Common histological patterns in glomerular epithelial cells in secondary focal segmental glomerulosclerosis.</a> Kidney International. 88 (5), 990-998 (2015).</li><li>Dijkman, H., Smeets, B., van der Laak, J., Steenbergen, E., Wetzels, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+parietal+epithelial+cell+is+crucially+involved+in+human+idiopathic+focal+segmental+glomerulosclerosis.">The parietal epithelial cell is crucially involved in human idiopathic focal segmental glomerulosclerosis.</a> Kidney International. 68 (4), 1562-1572 (2005).</li><li>Smeets, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Parietal+epithelial+cells+participate+in+the+formation+of+sclerotic+lesions+in+focal+segmental+glomerulosclerosis.">Parietal epithelial cells participate in the formation of sclerotic lesions in focal segmental glomerulosclerosis.</a> Journal of the American Society of Nephrology: JASN. 22 (7), 1262-1274 (2011).</li><li>Smeets, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tracing+the+origin+of+glomerular+extracapillary+lesions+from+parietal+epithelial+cells.">Tracing the origin of glomerular extracapillary lesions from parietal epithelial cells.</a> Journal of the American Society of Nephrology: JASN. 20 (12), 2604-2615 (2009).</li><li>Smeets, B., Moeller, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Parietal+epithelial+cells+and+podocytes+in+glomerular+diseases.">Parietal epithelial cells and podocytes in glomerular diseases.</a> Seminars in Nephrology. 32 (4), 357-367 (2012).</li><li>Ryu, 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=Plasma+leakage+through+glomerular+basement+membrane+ruptures+triggers+the+proliferation+of+parietal+epithelial+cells+and+crescent+formation+in+non-inflammatory+glomerular+injury.">Plasma leakage through glomerular basement membrane ruptures triggers the proliferation of parietal epithelial cells and crescent formation in non-inflammatory glomerular injury.</a> The Journal of Pathology. 228 (4), 482-494 (2012).</li><li>Eymael, J., Smeets, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Origin+and+fate+of+the+regenerating+cells+of+the+kidney.">Origin and fate of the regenerating cells of the kidney.</a> European Journal of Pharmacology. 790, 62-73 (2016).</li><li>Smeets, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Renal+progenitor+cells+contribute+to+hyperplastic+lesions+of+podocytopathies+and+crescentic+glomerulonephritis.">Renal progenitor cells contribute to hyperplastic lesions of podocytopathies and crescentic glomerulonephritis.</a> Journal of the American Society of Nephrology: JASN. 20 (12), 2593-2603 (2009).</li><li>Eymael, 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=CD44+is+required+for+the+pathogenesis+of+experimental+crescentic+glomerulonephritis+and+collapsing+focal+segmental+glomerulosclerosis.">CD44 is required for the pathogenesis of experimental crescentic glomerulonephritis and collapsing focal segmental glomerulosclerosis.</a> Kidney International. 93 (3), 626-642 (2018).</li><li>Roeder, S. 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=Activated+ERK1/2+increases+CD44+in+glomerular+parietal+epithelial+cells+leading+to+matrix+expansion.">Activated ERK1/2 increases CD44 in glomerular parietal epithelial cells leading to matrix expansion.</a> Kidney International. 91 (4), 896-913 (2017).</li><li>Appel, D., 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=Recruitment+of+podocytes+from+glomerular+parietal+epithelial+cells.">Recruitment of podocytes from glomerular parietal epithelial cells.</a> Journal of the American Society of Nephrology: JASN. 20 (2), 333-343 (2009).</li><li>Yaoita, 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=Visceral+epithelial+cells+in+rat+glomerular+cell+culture.">Visceral epithelial cells in rat glomerular cell culture.</a> European Journal of Cell Biology. 67 (2), 136-144 (1995).</li><li>Kuppe, 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=Investigations+of+Glucocorticoid+Action+in+GN.">Investigations of Glucocorticoid Action in GN.</a> Journal of the American Society of Nephrology: JASN. 28 (5), 1408-1420 (2017).</li><li>Ohse, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+of+conditionally+immortalized+mouse+glomerular+parietal+epithelial+cells+in+culture.">Establishment of conditionally immortalized mouse glomerular parietal epithelial cells in culture.</a> Journal of the American Society of Nephrology: JASN. 19 (10), 1879-1890 (2008).</li></ol>

Using the protocol described in this article, one can use single encapsulated glomeruli to evaluate parietal epithelial cell proliferation which is a consequence of parietal epithelial cell activation. This ex vivo model will enable us to study in detail the molecular pathways, which are involved in parietal epithelial cell activation. The described method relies on the simple concept of kidney dissection and sieving to isolate and culture encapsulated glomeruli and to compare proliferation and/or migration of parietal e...

Glomerular diseases are an important group of kidney disorders and represent a major cause of end stage renal disease (ESRD). Unfortunately, specific treatment options are limited and progression to ESRD is inevitable. Glomerular diseases are defined by the presence of glomerular injury and can be grouped in inflammatory and non-inflammatory diseases. Although the initial insult is different, recent studies have shown that a common cellular mechanism leads to glomerular epithelial cell hyperplasia and ultimately to glomerulosclerosis in all glomerular diseases, irrespective of the underlying cause1,2,3,4.
Specifically, it was shown that glomerulosclerotic lesions are mainly composed of activated parietal epithelial cells5,6. Under physiological conditions, parietal epithelial cells are flat quiescent epithelial cells that line the Bowman&#39;s capsule of the glomerulus. However, any glomerular injury either due to genetic mutations (e.g., podocyte specific or mitochondrial cytopathies), inflammation or hyperfiltration (e.g., caused by reduced renal mass, hypertension, obesity or diabetic mellitus) can trigger the activation of parietal epithelial cells. Activated parietal epithelial cells proliferate and deposit extracellular matrix which results in the formation of cellular crescents or sclerotic lesions5,7,8. Progression of these processes results in loss of renal function9. Therefore, parietal epithelial cell activation is a key factor in the development and progression of glomerulosclerosis in both inflammatory and non-inflammatory glomerular diseases1,2,3,4,10.
The molecular processes mediating parietal epithelial cell activation are still largely unknown. Recent studies show that activated parietal epithelial cells de novo express CD44, a receptor that is important for the activation of different pathways involved in cellular proliferation and migration. Furthermore, inhibition of CD44 was shown to inhibit parietal epithelial cell activation and attenuate the progression of crescent formation and glomerulosclerosis in animal models of inflammatory as well as non-inflammatory glomerular diseases11,12.
As parietal epithelial cell activation is a key player for the development of glomerulosclerosis and crescent formation, inhibition of these cells could slow down the progression of glomerular diseases. Elucidation of the molecular pathways driving parietal epithelial cell activation may lead to the development of specific therapeutic interventions that attenuate the formation of the hyperplastic and glomerulosclerotic lesions in glomerular disease.
In experimental animal models, it is frequently difficult to provide evidence for a direct effect of an altered gene expression (knock-out models or transgenic mouse models) or drug treatment on the parietal epithelial cells. In a conventional knock-out mouse the observed in vivo changes might be explained by direct changes in parietal epithelial cells. However, since the gene expression is also altered in other cell types within the mouse, one cannot exclude indirect effects mediated by other cell types. The development of conditional cre-lox mice driven by promoters mainly active in parietal epithelial cells has provided a solution in some cases13. Nevertheless, conditional transgenic models are complex and although more conditional lines become available, for many of the conventional knock-out or transgenic mouse lines there is not yet a conditional substitute.
To study the direct effects on parietal epithelial cells, our group has developed an ex vivo assay using single encapsulated glomeruli&#160;isolated&#160;from mouse kidneys to measure and analyze parietal epithelial cell proliferation and migration. This method will enable us to determine parietal epithelial cell specific effects and to find responsible pathways for parietal epithelial cell activation and test treatment options to inhibit this activation.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >24-well cell culture plate</td>
			<td >Corning Costar</td>
			<td ></td>
		</tr>
		<tr >
			<td >anti-CD31</td>
			<td>BD Pharmingen</td>
			<td>Endothelial cell marker (used concentration 1:200)</td>
		</tr>
		<tr >
			<td >chicken-anti-rat Alexa 647</td>
			<td>Thermo Fisher</td>
			<td>&#160;(used concentration 1:200)</td>
		</tr>
		<tr >
			<td >DAPI-Fluoromount G</td>
			<td>Southern Biotech</td>
			<td>Mounting medium containing DAPI</td>
		</tr>
		<tr >
			<td >Digital inverted light microscope</td>
			<td>Westburg, EVOS fl microscope</td>
			<td></td>
		</tr>
		<tr >
			<td >donkey-anti-goat Alexa 568</td>
			<td>Thermo Fisher</td>
			<td>&#160;(used concentration 1:200)</td>
		</tr>
		<tr >
			<td >donkey-anti-rabbit Alexa 568</td>
			<td>Thermo Fisher</td>
			<td>&#160;(used concentration 1:200)</td>
		</tr>
		<tr >
			<td >Dulbecco&#39;s Modified Eagle&#39;s medium&#160;</td>
			<td>Lonza</td>
			<td></td>
		</tr>
		<tr >
			<td >EBM Medium</td>
			<td>Lonza</td>
			<td></td>
		</tr>
		<tr >
			<td >EBM-MV Single Quots kit</td>
			<td>Lonza</td>
			<td>containing hydrocortisone, hEGF, GA-1000, FBS and BBE</td>
		</tr>
		<tr >
			<td >Fetal Bovine Serum</td>
			<td>Lonza</td>
			<td></td>
		</tr>
		<tr >
			<td >Fetal Calf Serum</td>
			<td>Lonza</td>
			<td></td>
		</tr>
		<tr >
			<td >Fluorescent microscope</td>
			<td>Leica Microsystems GmbH</td>
			<td></td>
		</tr>
		<tr >
			<td >goat-anti-synaptopodin</td>
			<td>Santa Cruz</td>
			<td>Podocyte marker (used concentration 1:200)</td>
		</tr>
		<tr >
			<td >Hanks&#39;Balanced Salt Solution</td>
			<td>Gibco</td>
			<td></td>
		</tr>
		<tr >
			<td >ImageJ software</td>
			<td >FIJI 1.51n</td>
			<td></td>
		</tr>
		<tr >
			<td >petri dish</td>
			<td >Sarstedt</td>
			<td>size 100</td>
		</tr>
		<tr >
			<td >rabbit-anti-claudin1</td>
			<td>Abcam</td>
			<td>Parietal epithelial cell marker (used concentration 1:100)</td>
		</tr>
		<tr >
			<td >rabbit-anti-SSeCKS</td>
			<td>Roswell Park Comprehensive Cancer Center,Buffalo, NY, USA</td>
			<td>kindly provided by Dr. E. Gelman, Parietal epithelial cell marker</td>
		</tr>
		<tr >
			<td >rat-anti-CD44</td>
			<td>BD Pharmingen</td>
			<td>Parietal epithelial cell marker (used concentration 1:200)</td>
		</tr>
		<tr >
			<td >scalpel</td>
			<td >Dahlhausen</td>
			<td>size 10</td>
		</tr>
		<tr >
			<td >Sieves&#160;</td>
			<td >Endecotts Ltd</td>
			<td>size 300 &#181;m, 75 &#181;m, 53 &#181;m, steel</td>
		</tr>
		<tr >
			<td >syringe</td>
			<td >BD Plastipak</td>
			<td>size: 20 ml</td>
		</tr>
		<tr >
			<td >Ultra-Low Attachment Microplates&#160;</td>
			<td>Corning Costar</td>
			<td>6-well plates</td>
		</tr>
	</tbody>
</table>

glomerular outgrowth as an ex vivo assay to analyze pathways involved in parietal epithelial cell activation

Parietal epithelial cell (PEC) activation is one of the key factors involved in the development and progression of glomerulosclerosis. Inhibition of pathways involved in parietal epithelial cell activation could therefore be a tool to attenuate the progression of glomerular diseases. This article describes a method to culture and analyze parietal epithelial cell outgrowth of encapsulated glomeruli isolated from mouse kidney. After dissecting isolated mouse kidneys, the tissue is minced, and glomeruli are isolated by sieving. Encapsulated glomeruli are collected, and single glomeruli are cultured for 6 days to obtain glomerular outgrowth of parietal epithelial cells. During this period, parietal epithelial cell proliferation and migration can be analyzed by determining the cell number or the surface area of outgrowing cells. This assay can therefore be used as a tool to study the effects of an altered gene expression in transgenic- or knockout-mice or the effects of culture conditions on parietal epithelial cell growth characteristics and signaling. Using this method, important pathways involved in the process of parietal epithelial cell activation and consequently in glomerulosclerosis can be studied.

A systematic diagram of the method to perform the glomerular outgrowth assay is shown in Figure 1. Figure 2A-D shows glomerular outgrowths of encapsulated glomeruli at different time points as observed using light microscopy. Outgrowths are shown at day 2, 4 and 6 (Figure 2B-D) in culture after glomerulus isolation from mouse kidney. In order to validate that the out...

Watch this Scientific Journal Video about Glomerular Outgrowth as an Ex Vivo Assay to Analyze Pathways Involved in Parietal Epithelial Cell Activation at JoVE.com

Glomerular Outgrowth as an Ex Vivo Assay to Analyze Pathways Involved in Parietal Epithelial Cell Activation

This article describes a method for culturing and analyzing glomerular parietal epithelial cell outgrowths of encapsulated glomeruli isolated from mouse kidney. This method can be used to study pathways involved in parietal epithelial cell proliferation and migration.

Parietal epithelial cell (PEC) activation is one of the key factors involved in the development and progression of glomerulosclerosis. Inhibition of ...

Activation of parietal epithelial cells is in key factor in the development of scar tissue in the glomerulus of the kidney. Using this method, we can study the cellular processes involved in this activation and hopefully find treatment options to slow down or even stop disease progression. The main advantage of our technique is that we use primary cells that grow straight from the isolated glomeruli.After freeing the kidneys, as outlined in the text manuscript, hold the kidney with the surgical forceps and use another pair of forceps to pull off the renal capsules. After this, place the kidneys into the wells of a six well culture plate that each contain two milliliters of HBSS and place the culture plate on ice. First, transfer the kidneys to a 100 millimeter Petri dish and use two scalpels to mince them into small pieces that are approximately one to two millimeters.Keep the minced kidney pieces wet with HBSS. Next, place the kidney pieces on top of a 300 micrometer metal sieve and press the kidney through the sieve using the plunger from a 20 milliliters syringe. Repeatedly rinse the sieve with HBSS in between and use a serological pipette to collect the flow-through and transfer it to a clean Petri dish.Use a scalpel to scrape off everything that remains in the bottom of the sieve and transfer it to the collected kidney homogenate. Rinse the kidney homogenate through a 75 and 53 micrometer sieve with HBSS. Then, wash both sieves with HBSS to remove all of the smaller structures.Collect the kidney structures and material that remained in the sieves by washing the upper surface of each with DMEM supplemented with 20%fetal calf serum and transfer the material to the wells of a six well ultra-low attachment microplate. Bring the ultra-low attachment microplate to an inverted light microscope and use a 20 microliter pipette took collect single encapsulated and or decapsulated glomeruli. After catching a single glomerulus in the pipette tip, add fresh DMEM medium without collected kidney material into the same pipette tip to a volume of 20 microliters.Transfer the single glomerulus with the DMEM medium to the center of a well of a 24 well cell culture plate and incubate at 37 degrees Celsius with 5%carbon dioxide for three hours to allow attachment of the glomerulus to the center of the well. After the incubation, the glomerulus will be attached to the center of the well. Carefully add 500 microliters of endothelial Basal medium supplemented with a growth factor kit and an additional 5%FBS and 1%penicillin and streptomycin to each well.Culture the single glomeruli at 37 degrees Celsius with 5%carbon dioxide for six days. After six days of incubation, use a digital inverted light microscope to take images and analyze the glomerular outgrowth. Using an image analysis software, determine the surface area of glomerular outgrowth by opening one of the image files with a scale bar.Draw a straight line on the scale bar and click on Analyze, then measure to determine the distance in pixels. To determine the scale, click Analyze and Set Scale and input the known distance in pixels, the known distance, and the unit of length. Click Okay when finished.Click on Analyze and Set Measurements. Then, check the options for Area and Display Label. Click Okay when finished.Next, draw a freehand selection around the glomerular outgrowth. Click Analyze and measure to display a results table, which contains the surface area of outgrowth in the earlier determined scale. in this study, the glomerular parietal epithelial cell outgrowths of encapsulated glomeruli are isolated from mouse kidneys, cultured, and analyzed.Representative light microscopy images show the glomerular outgrowths at different time points during the culture after the glomerulus are isolated from the mouse kidneys. In order to validate that the outgrowing cells are parietal epithelial cells, decapsulated glomeruli are also isolated and cultured for six days. Decapsulated glomeruli show no cell outgrowth during this incubation period.Immunofluorescent staining is then performed for different parietal epithelial cell markers, photo site specific markers, as well as endothelial cell markers. The results validate that the outgrowing cells, indeed, are parietal epithelial cells. Glomeruli associated from CD44 knockout mice show a decreased number of outgrowing cells, as well as a decreased surface area of glomerular outgrowth compared to the glomeruli isolated from wild type mice.This suggests an important role for CD44 in parietal epithelial cell activation. Using this technique, it's also possible to study the effects on drugs on parietal epithelial cell activation. This can be done by treating the isolated glomeruli with the drug of your choice and to analyze the differences in cell growth and cell migration.

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Biology

Ex Vivo Culture of Primary Human Fallopian Tube Epithelial Cells

Epithelial ovarian cancer is a leading cause of female cancer mortality in the United States. In contrast to other women-specific cancers, like breast and uterine carcinomas, where death rates have fallen in recent years, ovarian cancer cure rates have remained relatively unchanged over the past two decades 1. This is largely due to the lack of appropriate screening tools for detection of early stage disease where surgery and chemotherapy are most effective 2, 3. As a result, most patients present with advanced stage disease and diffuse abdominal involvement. This is further complicated by the fact that ovarian cancer is a heterogeneous disease with multiple histologic subtypes 4, 5. Serous ovarian carcinoma (SOC) is the most common and aggressive subtype and the form most often associated with mutations in the BRCA genes. Current experimental models in this field involve the use of cancer cell lines and mouse models to better understand the initiating genetic events and pathogenesis of disease 6, 7. Recently, the fallopian tube has emerged as a novel site for the origin of SOC, with the fallopian tube (FT) secretory epithelial cell (FTSEC) as the proposed cell of origin 8, 9. There are currently no cell lines or culture systems available to study the FT epithelium or the FTSEC. Here we describe a novel ex vivo culture system where primary human FT epithelial cells are cultured in a manner that preserves their architecture, polarity, immunophenotype, and response to physiologic and genotoxic stressors. This ex vivo model provides a useful tool for the study of SOC, allowing a better understanding of how tumors can arise from this tissue, and the mechanisms involved in tumor initiation and progression.

Ex Vivo Culture of Primary Human Fallopian Tube Epithelial Cells

The fallopian tube (FT) is emerging as an alternative site of origin for serous ovarian carcinoma (SOC). This protocol describes a novel method for the isolation and ex vivo culture of fallopian tube epithelial cells. This system recapitulates the in vivo epithelium and allows the study of SOC pathogenesis.

Epithelial ovarian cancer is a leading cause of female cancer mortality in the United States. In contrast to other women-specific cancers, like breast and ...

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c

Apoptosis, or programmed cell death, is a conserved and highly regulated pathway by which cells die1. Apoptosis can be triggered when cells encounter a wide range of cytotoxic stresses. These insults initiate signaling cascades that ultimately cause the release of cytochrome c from the mitochondrial intermembrane space to the cytoplasm2. The release of cytochrome c from mitochondria is a key event that triggers the rapid activation of caspases, the key cellular proteases which ultimately execute cell death3-4.
The pathway of apoptosis is regulated at points upstream and downstream of cytochrome c release from mitochondria5. In order to study the post-mitochondrial regulation of caspase activation, many investigators have turned to direct cytoplasmic microinjection of holocytochrome c (heme-attached) protein into cells6-9. Cytochrome c is normally localized to the mitochondria where attachment of a heme group is necessary to enable it to activate apoptosis10-11. Therefore, to directly activate caspases, it is necessary to inject the holocytochrome c protein instead of its cDNA, because while the expression of cytochrome c from cDNA constructs will result in mitochondrial targeting and heme attachment, it will be sequestered from cytosolic caspases. Thus, the direct cytosolic microinjection of purified heme-attached cytochrome c protein is a useful tool to mimic mitochondrial cytochrome c release and apoptosis without the use of toxic insults which cause cellular and mitochondrial damage.
In this article, we describe a method for the microinjection of cytochrome c protein into cells, using mouse embryonic fibroblasts (MEFs) and primary sympathetic neurons as examples. While this protocol focuses on the injection of cytochrome c for investigations of apoptosis, the techniques shown here can also be easily adapted for microinjection of other proteins of interest.

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c

In this protocol, we describe the direct cytoplasmic microinjection of cytochrome c protein into fibroblasts and primary sympathetic neurons. This technique allows for the introduction of cytochrome c protein into the cytoplasm of cells and mimics the release of cytochrome c from mitochondria, which occurs during apoptosis.

Apoptosis, or programmed cell death, is a conserved and highly regulated pathway by which cells die1.  Apoptosis can be triggered when cells encounter a ...

Chromatin Isolation by RNA Purification (ChIRP)

Long noncoding RNAs are key regulators of chromatin states for important biological processes such as dosage compensation, imprinting, and developmental gene expression 1,2,3,4,5,6,7. The recent discovery of thousands of lncRNAs in association with specific chromatin modification complexes, such as Polycomb Repressive Complex 2 (PRC2) that mediates histone H3 lysine 27 trimethylation (H3K27me3), suggests broad roles for numerous lncRNAs in managing chromatin states in a gene-specific fashion 8,9. While some lncRNAs are thought to work in cis on neighboring genes, other lncRNAs work in trans to regulate distantly located genes. For instance, Drosophila lncRNAs roX1 and roX2 bind numerous regions on the X chromosome of male cells, and are critical for dosage compensation 10,11. However, the exact locations of their binding sites are not known at high resolution. Similarly, human lncRNA HOTAIR can affect PRC2 occupancy on hundreds of genes genome-wide 3,12,13, but how specificity is achieved is unclear. LncRNAs can also serve as modular scaffolds to recruit the assembly of multiple protein complexes. The classic trans-acting RNA scaffold is the TERC RNA that serves as the template and scaffold for the telomerase complex 14; HOTAIR can also serve as a scaffold for PRC2 and a H3K4 demethylase complex 13.
Prior studies mapping RNA occupancy at chromatin have revealed substantial insights 15,16, but only at a single gene locus at a time. The occupancy sites of most lncRNAs are not known, and the roles of lncRNAs in chromatin regulation have been mostly inferred from the indirect effects of lncRNA perturbation. Just as chromatin immunoprecipitation followed by microarray or deep sequencing (ChIP-chip or ChIP-seq, respectively) has greatly improved our understanding of protein-DNA interactions on a genomic scale, here we illustrate a recently published strategy to map long RNA occupancy genome-wide at high resolution 17. This method, Chromatin Isolation by RNA Purification (ChIRP) (Figure 1), is based on affinity capture of target lncRNA:chromatin complex by tiling antisense-oligos, which then generates a map of genomic binding sites at a resolution of several hundred bases with high sensitivity and low background. ChIRP is applicable to many lncRNAs because the design of affinity-probes is straightforward given the RNA sequence and requires no knowledge of the RNA's structure or functional domains.

Chromatin Isolation by RNA Purification ChIRP

ChIRP is a novel and rapid technique to map genomic binding sites of long noncoding RNAs (lncRNAs). The method takes advantage of the specificity of anti-sense tiling oligonucleotides to allow the enumeration of lncRNA-bound genomic sites.

Long noncoding RNAs are key regulators of chromatin states for important biological processes such as dosage compensation, imprinting, and developmental ...

Rapid Genetic Analysis of Epithelial-Mesenchymal Signaling During Hair Regeneration

Hair follicle morphogenesis, a complex process requiring interaction between epithelia-derived keratinocytes and the underlying mesenchyme, is an attractive model system to study organ development and tissue-specific signaling. Although hair follicle development is genetically tractable, fast and reproducible analysis of factors essential for this process remains a challenge. Here we describe a procedure to generate targeted overexpression or shRNA-mediated knockdown of factors using lentivirus in a tissue-specific manner. Using a modified version of a hair regeneration model 5, 6, 11, we can achieve robust gain- or loss-of-function analysis in primary mouse keratinocytes or dermal cells to facilitate study of epithelial-mesenchymal signaling pathways that lead to hair follicle morphogenesis. We describe how to isolate fresh primary mouse keratinocytes and dermal cells, which contain dermal papilla cells and their precursors, deliver lentivirus containing either shRNA or cDNA to one of the cell populations, and combine the cells to generate fully formed hair follicles on the backs of nude mice. This approach allows analysis of tissue-specific factors required to generate hair follicles within three weeks and provides a fast and convenient companion to existing genetic models.

Tissue-specific analysis of a hair follicle regeneration model using lentivirus to mediate gain- or loss-of-function.

Hair follicle morphogenesis, a complex process requiring interaction between epithelia-derived keratinocytes and the underlying mesenchyme, is an ...

An Ex vivo Culture System to Study Thyroid Development

The thyroid is a bilobated endocrine gland localized at the base of the neck, producing the thyroid hormones T3, T4, and calcitonin. T3 and T4 are produced by differentiated thyrocytes, organized in closed spheres called follicles, while calcitonin is synthesized by C-cells, interspersed in between the follicles and a dense network of blood capillaries. Although adult thyroid architecture and functions have been extensively described and studied, the formation of the &#8220;angio-follicular&#8221; units, the distribution of C-cells in the parenchyma and the paracrine communications between epithelial and endothelial cells is far from being understood.
This method describes the sequential steps of mouse embryonic thyroid anlagen dissection and its culture on semiporous filters or on microscopy plastic slides. Within a period of four days, this culture system faithfully recapitulates in vivo thyroid development. Indeed, (i) bilobation of the organ occurs (for e12.5 explants), (ii) thyrocytes precursors organize into follicles and polarize, (iii) thyrocytes and C-cells differentiate, and (iv) endothelial cells present in the microdissected tissue proliferate, migrate into the thyroid lobes, and closely associate with the epithelial cells, as they do in vivo.
Thyroid tissues can be obtained from wild type, knockout or fluorescent transgenic embryos. Moreover, explants culture can be manipulated by addition of inhibitors, blocking antibodies, growth factors, or even cells or conditioned medium. Ex vivo development can be analyzed in real-time, or at any time of the culture by immunostaining and RT-qPCR.
In conclusion, thyroid explant culture combined with downstream whole-mount or on sections imaging and gene expression profiling provides a powerful system for manipulating and studying morphogenetic and differentiation events of thyroid organogenesis.

An Ex vivo Culture System to Study Thyroid Development

This protocol describes dissection of mouse embryonic thyroid anlagen and the culture of explants on semiporous filters or on microscopy plastic slides. This system is ideal to study morphogenetic or differentiation events occurring during thyroid development of wild type or knockout embryos, and is amenable to gain- and loss-of-function experiments.

The thyroid is a bilobated endocrine gland localized at the base of the neck, producing the thyroid hormones T3, T4, and calcitonin. T3 and T4 are ...

Mouse Fetal Whole Intestine Culture System for Ex Vivo Manipulation of Signaling Pathways and Three-dimensional Live Imaging of Villus Development

Most morphogenetic processes in the fetal intestine have been inferred from thin sections of fixed tissues, providing snapshots of changes over developmental stages. Three-dimensional information from thin serial sections can be challenging to interpret because of the difficulty of reconstructing serial sections perfectly and maintaining proper orientation of the tissue over serial sections. Recent findings by Grosse et al., 2011 highlight the importance of three- dimensional information in understanding morphogenesis of the developing villi of the intestine1. Three-dimensional reconstruction of singly labeled intestinal cells demonstrated that the majority of the intestinal epithelial cells contact both the apical and basal surfaces. Furthermore, three-dimensional reconstruction of the actin cytoskeleton at the apical surface of the epithelium demonstrated that the intestinal lumen is continuous and that secondary lumens are an artifact of sectioning. Those two points, along with the demonstration of interkinetic nuclear migration in the intestinal epithelium, defined the developing intestinal epithelium as a pseudostratified epithelium and not stratified as previously thought1. The ability to observe the epithelium three-dimensionally was seminal to demonstrating this point and redefining epithelial morphogenesis in the fetal intestine. With the evolution of multi-photon imaging technology and three-dimensional reconstruction software, the ability to visualize intact, developing organs is rapidly improving. Two-photon excitation allows less damaging penetration deeper into tissues with high resolution. Two-photon imaging and 3D reconstruction of the whole fetal mouse intestines in Walton et al., 2012 helped to define the pattern of villus outgrowth2. Here we describe a whole organ culture system that allows ex vivo development of villi and extensions of that culture system to allow the intestines to be three-dimensionally imaged during their development.

Mouse Fetal Whole Intestine Culture System for Ex Vivo Manipulation of Signaling Pathways and Three-dimensional Live Imaging of Villus Development

Improved imaging technology is allowing three-dimensional imaging of organs during development. Here we describe a whole organ culture system that allows live imaging of the developing villi in the fetal mouse intestine.

Most morphogenetic processes in the fetal intestine have been inferred from thin sections of fixed tissues, providing snapshots of changes over ...

Real Time Analysis of Metabolic Profile in Ex Vivo Mouse Intestinal Crypt Organoid Cultures

The small intestinal mucosa exhibits a repetitive architecture organized into two fundamental structures: villi, projecting into the intestinal lumen and composed of mature enterocytes, goblet cells and enteroendocrine cells; and crypts, residing proximal to the submucosa and the muscularis, harboring adult stem and progenitor cells and mature Paneth cells, as well as stromal and immune cells of the crypt microenvironment. Until the last few years, in vitro studies of small intestine was limited to cell lines derived from either benign or malignant tumors, and did not represent the physiology of normal intestinal epithelia and the influence of the microenvironment in which they reside. Here, we demonstrate a method adapted from Sato et al. (2009) for culturing primary mouse intestinal crypt organoids derived from C57BL/6 mice. In addition, we present the use of crypt organoid cultures to assay the crypt metabolic profile in real time by measurement of basal oxygen consumption, glycolytic rate, ATP production and respiratory capacity. Organoids maintain properties defined by their source and retain aspects of their metabolic adaptation reflected by oxygen consumption and extracellular acidification rates. Real time metabolic studies in this crypt organoid culture system are a powerful tool to study crypt organoid energy metabolism, and how it can be modulated by nutritional and pharmacological factors.

Real Time Analysis of Metabolic Profile in Ex Vivo Mouse Intestinal Crypt Organoid Cultures

Small intestinal crypt organoids cultured ex vivo provide a tissue culture system that recapitulates growth of crypts dependent on stem cells and their niche. We established a method to assay the metabolic profile in real time in primary mouse crypt organoids. We found organoids maintain physiological properties defined by their source.

The small intestinal mucosa exhibits a repetitive architecture organized into two fundamental structures: villi, projecting into the intestinal lumen and ...

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

Many studies seek to identify and map the brain regions involved in specific physiological regulations. The proto-oncogene c-fos, an immediate early gene, is expressed in neurons in response to various stimuli. The protein product can be readily detected with immunohistochemical techniques leading to the use of c-FOS detection to map groups of neurons that display changes in their activity. In this article, we focused on the identification of brainstem neuronal populations involved in the ventilatory adaptation to hypoxia or hypercapnia. Two approaches were described to identify involved neuronal populations in vivo in animals and ex vivo in deafferented brainstem preparations. In vivo, animals were exposed to hypercapnic or hypoxic gas mixtures. Ex vivo, deafferented preparations were superfused with hypoxic or hypercapnic artificial cerebrospinal fluid. In both cases, either control in vivo animals or ex vivo preparations were maintained under normoxic and normocapnic conditions. The comparison of these two approaches allows the determination of the origin of the neuronal activation i.e., peripheral and/or central. In vivo and ex vivo, brainstems were collected, fixed, and sliced into sections. Once sections were prepared, immunohistochemical detection of the c-FOS protein was made in order to identify the brainstem groups of cells activated by hypoxic or hypercapnic stimulations. Labeled cells were counted in brainstem respiratory structures. In comparison to the control condition, hypoxia or hypercapnia increased the number of c-FOS labeled cells in several specific brainstem sites that are thus constitutive of the neuronal pathways involved in the adaptation of the central respiratory drive.

The c-FOS Protein Immunohistological Detection: A Useful Tool As a Marker of Central Pathways Involved in Specific Physiological Responses In Vivo and Ex Vivo

Here, we present a protocol based on c-FOS protein immunohistological detection, a classical technique used for the identification of neuronal populations involved in specific physiological responses in vivo and ex vivo.

Many studies seek to identify and map the brain regions involved in specific physiological regulations. The proto-oncogene c-fos, an immediate early gene, ...

In Vitro and In Vivo Approaches to Determine Intestinal Epithelial Cell Permeability

The intestinal barrier defends against pathogenic microorganism and microbial toxin. Its function is regulated by tight junction permeability and epithelial cell integrity, and disruption of the intestinal barrier function contributes to progression of gastrointestinal and systemic disease. Two simple methods are described here to measure the permeability of intestinal epithelium. In vitro, Caco-2BBe cells are plated in tissue culture wells as a monolayer and transepithelial electrical resistance (TER) can be measured by an epithelial (volt/ohm) meter. This method is convincing because of its user-friendly operation and repeatability. In vivo, mice are gavaged with 4 kDa fluorescein isothiocyanate (FITC)-dextran, and the FITC-dextran concentrations are measured in collected serum samples from mice to determine the epithelial permeability. Oral gavage provides an accurate dose, and therefore is the preferred method to measure the intestinal permeability in vivo. Taken together, these two methods can measure the permeability of the intestinal epithelium in vitro and in vivo, and hence be used to study the connection between diseases and barrier function.

In Vitro and In Vivo Approaches to Determine Intestinal Epithelial Cell Permeability

Two methods are presented here to determine intestinal barrier function. An epithelial meter (volt/ohm) is used for measurements of transepithelial electrical resistance of cultured epithelia directly in tissue culture wells. In mice, the FITC-dextran gavage method is used to determine the intestinal permeability in vivo.

The intestinal barrier defends against pathogenic microorganism and microbial toxin. Its function is regulated by tight junction permeability and ...

Forced Salivation As a Method to Analyze Vector Competence of Mosquitoes

Vector competence is defined as the potential of a mosquito species to transmit a mosquito-borne virus (mobovirus) to a vertebrate host. Viable virus particles are transmitted during a blood meal via the saliva of an infected mosquito. Forced salivation assays allow determining the vector potential on the basis of single mosquitoes, avoiding the use of animal experiments. The method is suitable to analyze a large number of mosquitoes in one experiment within a short period of time. Forced salivation assays were used to analyze 856 individual mosquitoes trapped in Germany, including two different Culex pipiens pipiens biotypes, Culex torrentium as well as Aedes albopictus, which were experimentally infected with Zika virus (ZIKV) and incubated at 18 &#176;C or 27 &#176;C for two and three weeks. The results indicated the lack of vector competence of the different Culex taxa for ZIKV. In contrast, Aedes albopictus was susceptible to ZIKV, but only at 27 &#176;C, with transmission rates similar to an Aedes aegypti laboratory colony tested in parallel.

For efficient control of mosquito borne virus transmission, the knowledge of the vector potential of respective mosquitoes is of particular interest. We describe forced salivation as a method to analyze vector competence of Aedes albopictus and three different Culex taxa for the transmission of Zika virus.

Vector competence is defined as the potential of a mosquito species to transmit a mosquito-borne virus (mobovirus) to a vertebrate host. Viable virus ...