This work was supported by the Intramural Research Program at the National Institute on Drug Abuse. We thank Doug Howard, Chris Richie, Lowella Fortuno, and Josh Hinkle for their contributions to developing this method.

1. In Vitro&#160;Assay: Detecting SERCaMP Release from a Stable SH-SY5Y Cell Line
<ol>
	<li>Plate SH-SY5Y-GLuc-ASARTDL (SERCaMP) in tissue culture treated plates at 150,000&#160;cells per cm2 of surface area. For 96 well plates, for example, seed 50,000 cells per well (Figure 1A). Grow SH-SY5Y cells in DMEM (high glucose, GlutaMAX, pyruvate) + 10% bovine growth serum + 1x penicillin/streptomycin.
	<ol>
		<li>Passage cells up to 15 times (Figure 1B). Higher passage n...

<ol>
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H., Verkhratsky, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraluminal+calcium+as+a+primary+regulator+of+endoplasmic+reticulum+function.">Intraluminal calcium as a primary regulator of endoplasmic reticulum function.</a> Cell Calcium. 38 (3-4), 303-310 (2005).</li><li>Fu, 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=Aberrant+lipid+metabolism+disrupts+calcium+homeostasis+causing+liver+endoplasmic+reticulum+stress+in+obesity.">Aberrant lipid metabolism disrupts calcium homeostasis causing liver endoplasmic reticulum stress in obesity.</a> Nature. 473 (7348), 528-531 (2011).</li><li>Micaroni, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+calcium+in+intracellular+trafficking.">The role of calcium in intracellular trafficking.</a> Curr Mol Med. 10 (8), 763-773 (2010).</li><li>Mekahli, D., Bultynck, G., Parys, J. 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Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bcl-2-mediated+alterations+in+endoplasmic+reticulum+Ca2++analyzed+with+an+improved+genetically+encoded+fluorescent+sensor.">Bcl-2-mediated alterations in endoplasmic reticulum Ca2+ analyzed with an improved genetically encoded fluorescent sensor.</a> Proc Natl Acad Sci U S A. 101 (50), 17404-17409 (2004).</li><li>Suzuki, 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=Imaging+intraorganellar+Ca2++at+subcellular+resolution+using+CEPIA.">Imaging intraorganellar Ca2+ at subcellular resolution using CEPIA.</a> Nat Commun. 5, 4153 (2014).</li><li>Rehberg, M., Lepier, A., Solchenberger, B., Osten, P., Blum, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+non-disruptive+strategy+to+target+calcium+indicator+dyes+to+the+endoplasmic+reticulum.">A new non-disruptive strategy to target calcium indicator dyes to the endoplasmic reticulum.</a> Cell Calcium. 44 (4), 386-399 (2008).</li><li>Henderson, M. J., Wires, E. S., Trychta, K. A., Richie, C. T., Harvey, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SERCaMP:+a+carboxy-terminal+protein+modification+that+enables+monitoring+of+ER+calcium+homeostasis.">SERCaMP: a carboxy-terminal protein modification that enables monitoring of ER calcium homeostasis.</a> Mol Biol Cell. 25 (18), 2828-2839 (2014).</li><li>Henderson, M. J., Richie, C. T., Airavaara, M., Wang, Y., Harvey, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesencephalic+astrocyte-derived+neurotrophic+factor+(MANF)+secretion+and+cell+surface+binding+are+modulated+by+KDEL+receptors.">Mesencephalic astrocyte-derived neurotrophic factor (MANF) secretion and cell surface binding are modulated by KDEL receptors.</a> J Biol Chem. 288 (6), 4209-4225 (2013).</li><li>Shipman, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+4-(2-hydroxyethyl)-1-piperazine&#235;thanesulfonic+acid+(HEPES)+as+a+tissue+culture+buffer.">Evaluation of 4-(2-hydroxyethyl)-1-piperazine&#235;thanesulfonic acid (HEPES) as a tissue culture buffer.</a> Proc Soc Exp Biol Med. 130 (1), 305-310 (1969).</li><li>Zigler, J. S., Lepe-Zuniga, J. L., Vistica, B., Gery, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+the+cytotoxic+effects+of+light-exposed+HEPES-containing+culture+medium.">Analysis of the cytotoxic effects of light-exposed HEPES-containing culture medium.</a> In Vitro Cell Dev Biol. 21 (5), 282-287 (1985).</li><li>Howard, D. B., Powers, K., Wang, Y., Harvey, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tropism+and+toxicity+of+adeno-associated+viral+vector+serotypes+1,+2,+5,+6,+7,+8,+and+9+in+rat+neurons+and+glia+in+vitro.">Tropism and toxicity of adeno-associated viral vector serotypes 1, 2, 5, 6, 7, 8, and 9 in rat neurons and glia in vitro.</a> Virology. 372 (1), 24-34 (2008).</li><li>Smeets, E. F., Heemskerk, J. W., Comfurius, P., Bevers, E. M., Zwaal, R. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thapsigargin+amplifies+the+platelet+procoagulant+response+caused+by+thrombin.">Thapsigargin amplifies the platelet procoagulant response caused by thrombin.</a> Thromb Haemost. 70 (6), 1024-1029 (1993).</li><li>Tannous, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gaussia+luciferase+reporter+assay+for+monitoring+biological+processes+in+culture+and+in+vivo.">Gaussia luciferase reporter assay for monitoring biological processes in culture and in vivo.</a> Nat Protoc. 4 (4), 582-591 (2009).</li><li>Sobrevals, 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=AAV+vectors+transduce+hepatocytes+in+vivo+as+efficiently+in+cirrhotic+as+in+healthy+rat+livers.">AAV vectors transduce hepatocytes in vivo as efficiently in cirrhotic as in healthy rat livers.</a> Gene Ther. 19 (4), 411-417 (2012).</li><li>Wang, Z., 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=Rapid+and+highly+efficient+transduction+by+double-stranded+adeno-associated+virus+vectors+in+vitro+and+in+vivo.">Rapid and highly efficient transduction by double-stranded adeno-associated virus vectors in vitro and in vivo.</a> Gene Ther. 10 (26), 2105-2111 (2003).</li><li>Seppen, 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=Adeno-associated+virus+vector+serotypes+mediate+sustained+correction+of+bilirubin+UDP+glucuronosyltransferase+deficiency+in+rats.">Adeno-associated virus vector serotypes mediate sustained correction of bilirubin UDP glucuronosyltransferase deficiency in rats.</a> Mol Ther. 13 (6), 1085-1092 (2006).</li><li>Hareendran, 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=Adeno-associated+virus+(AAV)+vectors+in+gene+therapy:+immune+challenges+and+strategies+to+circumvent+them.">Adeno-associated virus (AAV) vectors in gene therapy: immune challenges and strategies to circumvent them.</a> Rev Med Virol. 23 (6), 399-413 (2013).</li></ol>

This protocol highlights the in vitro and in vivo utility of GLuc-SERCaMP to monitor depletion of ER calcium. Although the protein modification to generate SERCaMP appears to generalize to other reporter proteins12, we chose Gaussia luciferase for its robust (200-1,000 fold greater) bioluminescence compared to other luciferases18. We demonstrate detectable thapsigargin-induced GLuc-SERCaMP release across a 100-fold dose range of GLuc-SERCaMP virus delivered to primary rat ...

The endoplasmic reticulum (ER) functions in many cellular capacities including protein folding, protein secretion, lipid homeostasis, and intracellular signaling1. Central to normal ER function is maintaining luminal calcium concentrations at ~5,000 times those found in the cytoplasm2-4. This energy intensive process is regulated by the sarco/endoplasmic reticulum calcium ATPase (SERCA), a pump that moves calcium ions into the ER. Efflux of calcium from the ER is mediated primarily by the ryanodine (RyR) and inositol triphosphate (IP3R) receptors. Because many ER processes are dependent on calcium, disrupting the store can lead to ER stress and eventual cell death.
ER calcium dysregulation has been observed in diseases including cardiomyopathy, diabetes, Alzheimer&#8217;s, and Parkinson&#8217;s5. Owing to the progressive nature of these diseases, it has been challenging to delineate the cause-effect relationship between pathogenesis and alterations in the ER calcium store. A number of technologies have allowed for significant advances in our understanding of ER calcium dynamics, including dyes and genetically encoded calcium indicators (GECIs). Low affinity calcium dyes, which increase in fluorescence when bound to Ca2+, can be loaded into cells to examine subcellular compartments with high concentrations of calcium6. GECIs, such as D1ER and CatchER allow for monitoring of calcium fluctuations with more precise control of subcellular localization7-9. Recently, another class of GECIs called calcium-measuring organelle-entrapped protein indicators (CEPIA) have been described10. A third approach combining genetics and small molecule chemistry is targeted-esterase dye loading (TED), which utilizes a genetically encoded carboxylesterase (targeted to the ER) with an ester-based calcium dye11.
While the aforementioned approaches have inherent strengths and weaknesses, they can provide valuable insight into ER calcium dynamics through acute measurements of fluorescence. They are, however, not optimal for the longitudinal studies often required to investigate disease progression. With the goal of devising a method to monitor calcium dynamics over extended periods of time, we identified and developed a protein modification to create the secreted ER calcium monitoring proteins (SERCaMPs)12.
SERCaMP circumvents several limitations associated with other methodologies, by providing a minimally invasive approach to repeatedly interrogate the ER calcium store. We have previously demonstrated that the carboxy-terminal peptide ASARTDL (alanine-serine-alanine-arginine-threonine-aspartic acid-leucine) is sufficient to promote ER retention; however, under conditions that cause decreases in ER calcium, the peptide sequence is no longer able to retain ER localization and the protein is secreted13. The basis of the SERCaMP technology is the appendage of ASARTDL to the carboxy-terminus of a secreted protein (e.g. Gaussia luciferase, or GLuc) such that secretion is triggered by ER calcium depletion, thus creating a robust reporter of ER calcium dysregulation12. The expression of GLuc-SERCaMP via transgenic methods enables biological fluids including cell culture medium and plasma to be analyzed for changes in GLuc activity as an indicator of ER calcium homeostasis. The method has applications for the longitudinal study of progressive alterations in the ER calcium store both in vitro and in vivo. The following protocol is written as a general outline for using GLuc-based SERCaMP to study ER calcium homeostasis, but the protocol can serve as a guide for alternative reporter SERCaMPs.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>1.5mL tubes</td>
			<td>Fisher&#160;</td>
			<td>02-682-550</td>
			<td></td>
		</tr>
		<tr>
			<td>10% NP-40 solution&#160;</td>
			<td>Pierce</td>
			<td>28324</td>
			<td>for intracellular GLuc assays</td>
		</tr>
		<tr>
			<td>1mL luer-lok syringes</td>
			<td>Fisher</td>
			<td>14-823-30</td>
			<td></td>
		</tr>
		<tr>
			<td>200uL filter tips</td>
			<td>Rainin</td>
			<td>RT-L200F</td>
			<td></td>
		</tr>
		<tr>
			<td>3-0 surgical sutures</td>
			<td>Fisher</td>
			<td>NC9598192</td>
			<td></td>
		</tr>
		<tr>
			<td>30g needles</td>
			<td>Fisher Scientific</td>
			<td>14-821-13A&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Adhesive microplate sealing sheets</td>
			<td>Thermo</td>
			<td>AB-0558</td>
			<td></td>
		</tr>
		<tr>
			<td>Alcohol prep pads</td>
			<td>Fisher</td>
			<td>22-246-073</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia Auto Flow System</td>
			<td>E-Z Anesthesia</td>
			<td>EZ-AF9000</td>
			<td></td>
		</tr>
		<tr>
			<td>Animal recovery chamber</td>
			<td>Lyon Vet</td>
			<td>ICU-912-004</td>
			<td></td>
		</tr>
		<tr>
			<td>B27 supplement</td>
			<td>Life Technologies</td>
			<td>17504-044</td>
			<td></td>
		</tr>
		<tr>
			<td>Betadine solution</td>
			<td>Fisher</td>
			<td>NC9386574</td>
			<td></td>
		</tr>
		<tr>
			<td>Bleach</td>
			<td>Clorox</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine growth serum</td>
			<td>Thermo</td>
			<td>SH30541.03</td>
			<td></td>
		</tr>
		<tr>
			<td>Coelenterazine, Native</td>
			<td>Regis Technologies</td>
			<td>1-361204-200</td>
			<td></td>
		</tr>
		<tr>
			<td>Cotton tipped applicators</td>
			<td>Puritan</td>
			<td>806-WC</td>
			<td></td>
		</tr>
		<tr>
			<td>Cutting needles 3/8 circle sutures</td>
			<td>WPI</td>
			<td>501803</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital ultrasconic cleaner</td>
			<td>Fisher Scientific</td>
			<td>FS60D</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM high glucose, GlutaMAX, pyruvate</td>
			<td>Life Technologies</td>
			<td>10569-010</td>
			<td></td>
		</tr>
		<tr>
			<td>DNA mass ladder</td>
			<td>Life Technologies</td>
			<td>10496-016</td>
			<td></td>
		</tr>
		<tr>
			<td>Gaussia luciferase (recombinant protein)</td>
			<td>Nanolight</td>
			<td>321-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Gaussia luciferase antibody (for WB, ICC, or IHC)</td>
			<td>New England Biolabs</td>
			<td>E8023S</td>
			<td>1:2000 (WB)</td>
		</tr>
		<tr>
			<td>Germinator 500</td>
			<td>CellPoint Scientific</td>
			<td>DS-401</td>
			<td></td>
		</tr>
		<tr>
			<td>Gluc assay plates (96 well, opaque)</td>
			<td>Fisher</td>
			<td>07-200-589</td>
			<td></td>
		</tr>
		<tr>
			<td>Hank&#39;s balanced salt solution</td>
			<td>Life Technologies</td>
			<td>14175-095</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>Allmedtech</td>
			<td>63323-276-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Butler Schein</td>
			<td>29404</td>
			<td></td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Henry Schein</td>
			<td>995-2949</td>
			<td></td>
		</tr>
		<tr>
			<td>Kwik Stop Styptic powder</td>
			<td>Butler Schein</td>
			<td>5867</td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamine</td>
			<td>Sigma</td>
			<td>G8540</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Fisher</td>
			<td>a452-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Microfuge 22R Centrifuge</td>
			<td>Bekman Colter</td>
			<td>368831</td>
			<td></td>
		</tr>
		<tr>
			<td>Neosporin</td>
			<td>Fisher</td>
			<td>19-898-143</td>
			<td></td>
		</tr>
		<tr>
			<td>Neurobasal medium</td>
			<td>Life Technologies</td>
			<td>21103049</td>
			<td></td>
		</tr>
		<tr>
			<td>Nikon Stereoscope</td>
			<td>Nikon</td>
			<td>SMZ745T</td>
			<td></td>
		</tr>
		<tr>
			<td>Nucleospin Gel and PCR Cleanup</td>
			<td>Machery-Nagel</td>
			<td>740609</td>
			<td></td>
		</tr>
		<tr>
			<td>P200 pipet</td>
			<td>Rainin</td>
			<td>L-200XLS+</td>
			<td></td>
		</tr>
		<tr>
			<td>p24 Lenti-X rapid titer kit</td>
			<td>Clontech</td>
			<td>632200</td>
			<td></td>
		</tr>
		<tr>
			<td>PCR film seal</td>
			<td>Fisher</td>
			<td>AB0558</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/streptomycin</td>
			<td>Life Technologies</td>
			<td>15140-122</td>
			<td></td>
		</tr>
		<tr>
			<td>Protease inhibitor cocktail</td>
			<td>Sigma</td>
			<td>P8340</td>
			<td></td>
		</tr>
		<tr>
			<td>ReFresh Charcoal Filter canister</td>
			<td>E-Z Anesthesia</td>
			<td>EZ-258</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel blades, #10</td>
			<td>Fine Science tools Inc</td>
			<td>10010-00</td>
			<td></td>
		</tr>
		<tr>
			<td>SD rats 150-200g</td>
			<td>Charles River</td>
			<td>Rats</td>
			<td>rats ordered at 150-200g.&#160; Surgery 5 days after arrival</td>
		</tr>
		<tr>
			<td>Small animal ear tags</td>
			<td>National Band and Tag co</td>
			<td>1005-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile surgical drapes</td>
			<td>Braintree Scientific</td>
			<td>SP-MPS</td>
			<td></td>
		</tr>
		<tr>
			<td>Synergy 2 plate reader</td>
			<td>BioTek</td>
			<td>n/a</td>
			<td></td>
		</tr>
		<tr>
			<td>TaqMan Universal PCR Master Mix</td>
			<td>Applied Biosystems</td>
			<td>4304437</td>
			<td></td>
		</tr>
		<tr>
			<td>Thapsigargin</td>
			<td>Sigma</td>
			<td>T9033</td>
			<td>harmful to human health</td>
		</tr>
		<tr>
			<td>Virapower lentiviral packaging mix</td>
			<td>Life Technologies</td>
			<td>K4975-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Xfect Transfection reagent</td>
			<td>Clontech</td>
			<td>631318</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Valley Vet</td>
			<td>468RX</td>
			<td></td>
		</tr>
	</tbody>
</table>

monitoring endoplasmic reticulum calcium homeostasis using a gaussia luciferase sercamp

The endoplasmic reticulum (ER) contains the highest level of intracellular calcium, with concentrations approximately 5,000-fold greater than cytoplasmic levels. Tight control over ER calcium is imperative for protein folding, modification and trafficking. Perturbations to ER calcium can result in the activation of the unfolded protein response, a three-prong ER stress response mechanism, and contribute to pathogenesis in a variety of diseases. The ability to monitor ER calcium alterations during disease onset and progression is important in principle, yet challenging in practice. Currently available methods for monitoring ER calcium, such as calcium-dependent fluorescent dyes and proteins, have provided insight into ER calcium dynamics in cells, however these tools are not well suited for in vivo studies. Our lab has demonstrated that a modification to the carboxy-terminus of Gaussia luciferase confers secretion of the reporter in response to ER calcium depletion. The methods for using a luciferase based, secreted ER calcium monitoring protein (SERCaMP) for in vitro and in vivo applications are described herein. This video highlights hepatic injections, pharmacological manipulation of GLuc-SERCaMP, blood collection and processing, and assay parameters for longitudinal monitoring of ER calcium.

The GLuc-SERCaMP method allows for assessment of ER calcium homeostasis by sampling extracellular fluids. Several controls can be included in the experimental design to enhance interpretation of results. First, use of a constitutively secreted reporter (e.g. GLuc without the C-terminal ASARTDL or &#8220;GLuc-No Tag&#8221;) can be employed to assess the effects of experimental treatments on the secretory pathway (global cellular secretion) and transgene expression. For instance, an increase in the extracellular l...

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Monitoring Endoplasmic Reticulum Calcium Homeostasis Using a Gaussia Luciferase SERCaMP

Endoplasmic reticulum calcium homeostasis is disrupted in diverse pathologies. A secreted ER calcium monitoring protein (SERCaMP) reporter can be used to detect disruptions in the ER calcium store. This protocol describes the use of a Gaussia luciferase SERCaMP to examine ER calcium homeostasis in vitro and in vivo.

Monitoring Endoplasmic Reticulum Calcium Homeostasis Using a Gaussia Luciferase SERCaMP

The endoplasmic reticulum (ER) contains the highest level of intracellular calcium, with concentrations approximately 5,000-fold greater than cytoplasmic ...

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13.0K vistas.  National Institutes of Health. Endoplasmic reticulum calcium homeostasis is disrupted in diverse pathologies. A secreted ER calcium monitoring protein (SERCaMP) reporter can be used to detect disruptions in the ER calcium store. This protocol describes the use of a Gaussia luciferase SERCaMP to examine ER calcium homeostasis in vitro and in vivo.