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.

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The authors have nothing to disclose.

Ce protocole met en évidence in vitro et in vivo de l&#39;utilité de Gluc-SERCaMP pour contrôler l&#39;épuisement de calcium ER. Bien que la modification de la protéine pour générer SERCaMP semble généraliser à d&#39;autres 12 protéines rapporteurs, nous avons choisi pour la luciférase de Gaussia son robuste (200-1,000 fois supérieure) bioluminescence par rapport aux autres luciférases 18. Nous démontrons détectable induite thapsigargine GLUC-SERCaMP libé...

Le réticulum endoplasmique (RE) des fonctions dans de nombreuses capacités cellulaires, y compris le repliement des protéines, la sécrétion de protéines, l&#39;homéostasie lipidique et de signalisation intracellulaire 1. Central à la fonction ER normale est de maintenir les concentrations de calcium luminal à ~ 5000 fois ceux trouvés dans le cytoplasme 2-4. Ce processus intensif d&#39;énergie est réglementée par la ATPase Sarco / réticulum endoplasmique de calcium (SERCA), une pompe qui déplace des ions calcium dans le RE. Efflux de calcium du RE est principalement médiée par la ryanodine (RyR) et l&#39;inositol triphosphate (IP3R) récepteurs. Parce que de nombreux processus de ER sont dépendantes du calcium, perturbant le magasin peut conduire à des stress du RE et la mort cellulaire éventuelle. ER dysrégulation de calcium a été observée dans les maladies y compris la cardiomyopathie, le diabète, la maladie d&#39;Alzheimer, la maladie de Parkinson et 5. En raison de la nature progressive de ces maladies, il a été difficile de délimiter la nouvelle cause à effetlation entre la pathogenèse et les modifications dans le magasin ER de calcium. Un certain nombre de technologies ont permis des avancées significatives dans notre compréhension de la dynamique ER de calcium, y compris les colorants et les indicateurs de calcium génétiquement codés (GeCIS). Des colorants à faible affinité de calcium, ce qui augmente la fluorescence lorsqu&#39;il est lié à Ca2 +, peuvent être chargées dans les cellules à examiner compartiments subcellulaires avec des concentrations élevées de calcium 6. GeCIS, comme D1ER et le receveur permettre un suivi des fluctuations de calcium avec un contrôle plus précis de la localisation subcellulaire 7-9. Récemment, une autre classe de GECIS appelés indicateurs de protéines organelles piégée calcium de mesure (CEPIA) ont été décrits 10. Une troisième approche combinant la génétique et la chimie des petites molécules ciblé est-estérase charge de colorant (TED), qui utilise une carboxylestérase codé génétiquement (ciblé pour l&#39;ER) avec un colorant à base d&#39;ester de calcium-11. Bien que la aforementioned approches ont des forces et des faiblesses inhérentes, ils peuvent fournir des informations précieuses sur la dynamique de calcium ER par des mesures aigus de fluorescence. Ils sont, cependant, pas optimal pour les études longitudinales souvent nécessaires pour enquêter sur la progression de la maladie. Dans le but de mettre au point une méthode pour surveiller la dynamique de calcium sur des périodes de temps prolongées, nous avons identifié et développé une modification des protéines pour créer les protéines sécrétées de calcium ER surveillance (SERCaMPs) 12. SERCaMP contourne plusieurs limitations associées avec d&#39;autres méthodes, en fournissant une approche minimalement invasive pour interroger plusieurs reprises la boutique ER de calcium. Nous avons précédemment démontré que le peptide ASARTDL carboxy-terminale (alanine-sérine-arginine-alanine-thréonine-leucine-acide aspartique) est suffisante pour favoriser la rétention au ER; cependant, dans des conditions qui causent des diminutions de calcium ER, la séquence peptidique est plus en mesure de maintenir ER localization et la protéine est sécrétée 13. La base de la technologie de SERCaMP est l&#39;appendice de ASARTDL à l&#39;extrémité carboxy-terminale d&#39;une protéine sécrétée (par exemple, la luciférase de Gaussia, ou Gluc) de telle sorte que la sécrétion est déclenchée par épuisement ER de calcium, créant ainsi un journaliste robuste de ER dysrégulation de calcium 12. L&#39;expression de Gluc-SERCaMP par des méthodes transgéniques permet fluides biologiques, notamment milieu de culture de cellules et le plasma à analyser les changements dans l&#39;activité Gluc comme indicateur de l&#39;homéostasie de calcium ER. La méthode a des applications pour l&#39;étude longitudinale des modifications progressives dans le magasin de calcium ER la fois in vitro et in vivo. Le protocole suivant est écrit comme un cadre général pour l&#39;aide basée SERCaMP-GLUC pour étudier ER homéostasie du calcium, mais le protocole peut servir de guide pour SERCaMPs rapporteurs alternatives.

<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

Le réticulum endoplasmique (RE) contient le plus haut niveau de calcium intracellulaire, avec des concentrations d&#39;environ 5000 fois plus élevée que les niveaux cytoplasmiques. Un contrôle serré sur ER calcium est impératif pour le repliement des protéines, la modification et la traite. Les perturbations à ER calcium peuvent conduire à l&#39;activation de la réponse de la protéine dépliée, un mécanisme de réponse au stress du RE à trois broches, et contribuer à la pathogenèse d&#39;une variété de maladies. La capacité de surveiller les modifications de calcium ER apparition et la progression au cours de la maladie est important en principe, mais difficile en pratique. Méthodes actuellement disponibles pour ER de surveillance de calcium, tels que les colorants et les protéines fluorescentes calcium-dépendante, ont permis de mieux comprendre la dynamique ER de calcium dans les cellules, mais ces outils ne sont pas bien adaptés pour des études in vivo. Notre laboratoire a démontré qu&#39;une modification de l&#39;extrémité carboxy-terminale de la luciférase de Gaussia confère sécrétion du rapporteur en réponse àER appauvrissement de calcium. Les procédés d&#39;utilisation d&#39;une luciférase en fonction, la protéine de surveillance de calcium du RE sécrétée (SERCaMP) pour in vitro et in vivo dans des applications sont décrits ici. Cette vidéo met injections hépatiques, la manipulation pharmacologique de GLUC-SERCaMP, la collecte et le traitement du sang, et les paramètres de dosage pour le suivi longitudinal de ER calcium.

La méthode GLUC-SERCaMP permet pour l&#39;évaluation des ER homéostasie calcique en échantillonnant les liquides extracellulaires. Plusieurs contrôles peuvent être inclus dans la conception expérimentale pour améliorer l&#39;interprétation des résultats. Tout d&#39;abord, l&#39;utilisation d&#39;un journaliste constitutivement sécrétée (par exemple GLUC sans ASARTDL C-terminale ou &quot;GLUC-Pas Tag&quot;) peut être utilisé pour évaluer les effets des traitements expérimentaux sur la voie de s?...

Watch this Scientific Journal Video about Monitoring Endoplasmic Reticulum Calcium Homeostasis Using a Gaussia Luciferase SERCaMP at JoVE.com

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.

Suivi réticulum endoplasmique homéostasie calcique l&#39;aide d&#39;un<em&gt; Gaussia</em&gt; Luciférase SERCaMP

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

monitoring-endoplasmic-reticulum-calcium-homeostasis-using-gaussia

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JoVE Journal

Biology

Monitoring Endoplasmic Reticulum Calcium Homeostasis Using a Gaussia Luciferase SERCaMP

13.0K vues.  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.

Vidéo: Monitoring Endoplasmic Reticulum Calcium Homeostasis Using a Gaussia Luciferase SERCaMP

Studying Membrane Biogenesis with a Luciferase-Based Reporter Gene Assay

To study the coordination of different lipid synthesis pathways during membrane biogenesis it is useful to work with an experimental system where membrane biogenesis occurs rapidly and in an inducible manner. We have found that phagocytosis of latex beads is practical for these purposes as cells rapidly synthesize membrane lipids to replenish membrane pools lost as  wrapping material  during particle engulfment. Here, we describe procedures for studying changes in phagocytosis-induced gene expression with a luciferase-based reporter gene approach using the Dual-Glo  Luciferase Assay System from Promega.

Here, we describe procedures for studying changes in phagocytosis-induced gene expression with a luciferase-based reporter gene approach using the Dual-GloTM Luciferase Assay System from Promega.

Etudier biogenèse des membranes avec un Luciferase Assay-Based gène rapporteur

To study the coordination of different lipid synthesis pathways during membrane biogenesis it is useful to work with an experimental system where membrane ...

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Biologie

Monitoring Dynamic Changes In Mitochondrial Calcium Levels During Apoptosis Using A Genetically Encoded Calcium Sensor

Dynamic changes in intracellular calcium concentration in response to various stimuli regulates many cellular processes such as proliferation, differentiation, and apoptosis1. During apoptosis, calcium accumulation in mitochondria promotes the release of pro-apoptotic factors from the mitochondria into the cytosol2. It is therefore of interest to directly measure mitochondrial calcium in living cells in situ during apoptosis. High-resolution fluorescent imaging of cells loaded with dual-excitation ratiometric and non-ratiometric synthetic calcium indicator dyes has been proven to be a reliable and versatile tool to study various aspects of intracellular calcium signaling. Measuring cytosolic calcium fluxes using these techniques is relatively straightforward. However, measuring intramitochondrial calcium levels in intact cells using synthetic calcium indicators such as rhod-2 and rhod-FF is more challenging. Synthetic indicators targeted to mitochondria have blunted responses to repetitive increases in mitochondrial calcium, and disrupt mitochondrial morphology3. Additionally, synthetic indicators tend to leak out of mitochondria over several hours which makes them unsuitable for long-term experiments. Thus, genetically encoded calcium indicators based upon green fluorescent protein (GFP)4 or aequorin5 targeted to mitochondria have greatly facilitated measurement of mitochondrial calcium dynamics. Here, we describe a simple method for real-time measurement of mitochondrial calcium fluxes in response to different stimuli. The method is based on fluorescence microscopy of 'ratiometric-pericam' which is selectively targeted to mitochondria. Ratiometric pericam is a calcium indicator based on a fusion of circularly permuted yellow fluorescent protein and calmodulin4. Binding of calcium to ratiometric pericam causes a shift of its excitation peak from 415 nm to 494 nm, while the emission spectrum, which peaks around 515 nm, remains unchanged. Ratiometric pericam binds a single calcium ion with a dissociation constant in vitro of ~1.7 &mu;M4. These properties of ratiometric pericam allow the quantification of rapid and long-term changes in mitochondrial calcium concentration. Furthermore, we describe adaptation of this methodology to a standard wide-field calcium imaging microscope with commonly available filter sets. Using two distinct agonists, the purinergic agonist ATP and apoptosis-inducing drug staurosporine, we demonstrate that this method is appropriate for monitoring changes in mitochondrial calcium concentration with a temporal resolution of seconds to hours. Furthermore, we also demonstrate that ratiometric pericam is also useful for measuring mitochondrial fission/fragmentation during apoptosis. Thus, ratiometric pericam is particularly well suited for continuous long-term measurement of mitochondrial calcium dynamics during apoptosis.

This protocol describes a method for real-time measurement of mitochondrial calcium fluxes by fluorescent imaging. The method takes advantage of a circularly permutated YFP-based dual-excitation ratiometric calcium sensor (ratiometric pericam-mt) selectively expressed in mitochondria.

Surveillance des changements dynamiques dans les niveaux de calcium mitochondrial cours de l&#39;apoptose en utilisant un capteur de calcium codées génétiquement

Dynamic changes in intracellular calcium concentration in response to various stimuli regulates many cellular processes such as proliferation, ...

In vitro Transcription and Capping of Gaussia Luciferase mRNA Followed by HeLa Cell Transfection

In vitro transcription is the synthesis of RNA transcripts by RNA polymerase from a linear DNA template containing the corresponding promoter sequence (T7, T3, SP6) and the gene to be transcribed (Figure 1A). A typical transcription reaction consists of the template DNA, RNA polymerase, ribonucleotide triphosphates, RNase inhibitor and buffer containing Mg2+ ions.
Large amounts of high quality RNA are often required for a variety of applications. Use of in vitro transcription has been reported for RNA structure and function studies such as splicing1, RNAi experiments in mammalian cells2, antisense RNA amplification by the "Eberwine method"3, microarray analysis4 and for RNA vaccine studies5. The technique can also be used for producing radiolabeled and dye labeled probes6. Warren, et al. recently reported reprogramming of human cells by transfection with in vitro transcribed capped RNA7. The T7 High Yield RNA Synthesis Kit from New England Biolabs has been designed to synthesize up to 180 &mu;g RNA per 20 &mu;l reaction. RNA of length up to 10kb has been successfully transcribed using this kit. Linearized plasmid DNA, PCR products and synthetic DNA oligonucleotides can be used as templates for transcription as long as they have the T7 promoter sequence upstream of the gene to be transcribed.
Addition of a 5' end cap structure to the RNA is an important process in eukaryotes. It is essential for RNA stability8, efficient translation9, nuclear transport10 and splicing11. The process involves addition of a 7-methylguanosine cap at the 5' triphosphate end of the RNA. RNA capping can be carried out post-transcriptionally using capping enzymes or co-transcriptionally using cap analogs. In the enzymatic method, the mRNA is capped using the Vaccinia virus capping enzyme12,13. The enzyme adds on a 7-methylguanosine cap at the 5' end of the RNA using GTP and S-adenosyl methionine as donors (cap 0 structure). Both methods yield functionally active capped RNA suitable for transfection or other applications14 such as generating viral genomic RNA for reverse-genetic systems15 and crystallographic studies of cap binding proteins such as eIF4E16.
In the method described below, the T7 High Yield RNA Synthesis Kit from NEB is used to synthesize capped and uncapped RNA transcripts of Gaussia luciferase (GLuc) and Cypridina luciferase (CLuc). A portion of the uncapped GLuc RNA is capped using the Vaccinia Capping System (NEB). A linearized plasmid containing the GLuc or CLuc gene and T7 promoter is used as the template DNA. The transcribed RNA is transfected into HeLa cells and cell culture supernatants are assayed for luciferase activity. Capped CLuc RNA is used as the internal control to normalize GLuc expression.

In vitro Transcription and Capping of Gaussia Luciferase mRNA Followed by HeLa Cell Transfection

This method describes high yield in vitro synthesis of both capped and uncapped mRNA from a linearized plasmid containing the Gaussia luciferase (GLuc) gene. The RNA is purified and a fraction of the uncapped RNA is enzymatically capped using the Vaccinia virus capping enzyme. In the final step, the mRNA is transfected into HeLa cells and cell culture supernatants are assayed for luciferase activity.

Transcription in vitro et plafonnement de l&#39;ARNm de luciférase Gaussia Suivie par la transfection de cellules HeLa

In vitro transcription is the synthesis of RNA transcripts by RNA polymerase from a linear DNA template containing the corresponding promoter sequence ...

Monitoring Cell-autonomous Circadian Clock Rhythms of Gene Expression Using Luciferase Bioluminescence Reporters

In mammals, many aspects of behavior and physiology such as sleep-wake cycles and liver metabolism are regulated by endogenous circadian clocks (reviewed1,2). The circadian time-keeping system is a hierarchical multi-oscillator network, with the central clock located in the suprachiasmatic nucleus (SCN) synchronizing and coordinating extra-SCN and peripheral clocks elsewhere1,2. Individual cells are the functional units for generation and maintenance of circadian rhythms3,4, and these oscillators of different tissue types in the organism share a remarkably similar biochemical negative feedback mechanism. However, due to interactions at the neuronal network level in the SCN and through rhythmic, systemic cues at the organismal level, circadian rhythms at the organismal level are not necessarily cell-autonomous5-7. Compared to traditional studies of locomotor activity in vivo and SCN explants ex vivo, cell-based in vitro assays allow for discovery of cell-autonomous circadian defects5,8. Strategically, cell-based models are more experimentally tractable for phenotypic characterization and rapid discovery of basic clock mechanisms5,8-13.
Because circadian rhythms are dynamic, longitudinal measurements with high temporal resolution are needed to assess clock function. In recent years, real-time bioluminescence recording using firefly luciferase as a reporter has become a common technique for studying circadian rhythms in mammals14,15, as it allows for examination of the persistence and dynamics of molecular rhythms. To monitor cell-autonomous circadian rhythms of gene expression, luciferase reporters can be introduced into cells via transient transfection13,16,17 or stable transduction5,10,18,19. Here we describe a stable transduction protocol using lentivirus-mediated gene delivery. The lentiviral vector system is superior to traditional methods such as transient transfection and germline transmission because of its efficiency and versatility: it permits efficient delivery and stable integration into the host genome of both dividing and non-dividing cells20. Once a reporter cell line is established, the dynamics of clock function can be examined through bioluminescence recording. We first describe the generation of P(Per2)-dLuc reporter lines, and then present data from this and other circadian reporters. In these assays, 3T3 mouse fibroblasts and U2OS human osteosarcoma cells are used as cellular models. We also discuss various ways of using these clock models in circadian studies. Methods described here can be applied to a great variety of cell types to study the cellular and molecular basis of circadian clocks, and may prove useful in tackling problems in other biological systems.

Circadian clocks function within individual cells, i.e., they are cell-autonomous. Here, we describe methods for generating cell-autonomous clock models using non-invasive, luciferase-based real-time bioluminescence technology. Reporter cells provide tractable, functional model systems for studying circadian biology.

Surveillance de cellules autonomes Rythmes horloge circadienne de l&#39;expression génique par Reporters Bioluminescence luciférase

In mammals, many aspects of behavior and physiology such as sleep-wake cycles and liver metabolism are regulated by endogenous circadian clocks ...

Visualization of Endoplasmic Reticulum Localized mRNAs in Mammalian Cells

In eukaryotes, most of the messenger RNAs (mRNAs) that encode secreted and membrane proteins are localized to the surface of the endoplasmic reticulum (ER). However, the visualization of these mRNAs can be challenging. This is especially true when only a fraction of the mRNA is ER-associated and their distribution to this organelle is obstructed by non-targeted (i.e. "free") transcripts. In order to monitor ER-associated mRNAs, we have developed a method in which cells are treated with a short exposure to a digitonin extraction solution that selectively permeabilizes the plasma membrane, and thus removes the cytoplasmic contents, while simultaneously maintaining the integrity of the ER. When this method is coupled with fluorescent in situ hybridization (FISH), one can clearly visualize ER-bound mRNAs by fluorescent microscopy. Using this protocol the degree of ER-association for either bulk poly(A) transcripts or specific mRNAs can be assessed and even quantified. In the process, one can use this assay to investigate the nature of mRNA-ER interactions.

Here we describe a method to visualize endoplasmic reticulum-associated mRNAs in mammalian tissue culture cells. This technique involves the selective permeabilization of the plasma membrane with digitonin to remove cytoplasmic contents followed by fluorescent in situ hybridization to detect either bulk poly(A) mRNA or specific transcripts.

Visualisation des ARNm localisés dans le réticulum endoplasmique des cellules de mammifères

In eukaryotes, most of the messenger RNAs (mRNAs) that encode secreted and membrane proteins are localized to the surface of the endoplasmic reticulum ...

High-throughput Functional Screening using a Homemade Dual-glow Luciferase Assay

We present a rapid and inexpensive high-throughput screening protocol to identify transcriptional regulators of alpha-synuclein, a gene associated with Parkinson&#39;s disease. 293T cells are transiently transfected with plasmids from an arrayed ORF expression library, together with luciferase reporter plasmids, in a one-gene-per-well microplate format. Firefly luciferase activity is assayed after 48 hr to determine the effects of each library gene upon alpha-synuclein transcription, normalized to expression from an internal control construct (a hCMV promoter directing Renilla luciferase). This protocol is facilitated by a bench-top robot enclosed in a biosafety cabinet, which performs aseptic liquid handling in 96-well format. Our automated transfection protocol is readily adaptable to high-throughput lentiviral library production or other functional screening protocols requiring triple-transfections of large numbers of unique library plasmids in conjunction with a common set of helper plasmids. We also present an inexpensive and validated alternative to commercially-available, dual luciferase reagents which employs PTC124, EDTA, and pyrophosphate to suppress firefly luciferase activity prior to measurement of Renilla luciferase. Using these methods, we screened 7,670 human genes and identified 68 regulators of alpha-synuclein. This protocol is easily modifiable to target other genes of interest.

We present a rapid and inexpensive screening method for identifying transcriptional regulators using high-throughput robotic transfections and a homemade dual-glow luciferase assay. This protocol rapidly generates direct side-by-side functional data for thousands of genes and is easily modifiable to target any gene of interest.

Criblage à haut débit fonctionnelle utilisant une maison double lueur de dosage de luciférase

We present a rapid and inexpensive high-throughput screening protocol to identify transcriptional regulators of alpha-synuclein, a gene associated with ...

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the function and regulation of protein folding was studied in vitro, in isolated tissue culture cells and in unicellular organisms. Recent studies have uncovered links between protein homeostasis (proteostasis), metabolism, development, aging, and temperature-sensing. These findings have led to the development of new tools for monitoring protein folding in the model metazoan organism Caenorhabditis elegans. In our laboratory, we combine behavioral assays, imaging and biochemical approaches using temperature-sensitive or naturally occurring metastable proteins as sensors of the folding environment to monitor protein misfolding. Behavioral assays that are associated with the misfolding of a specific protein provide a simple and powerful readout for protein folding, allowing for the fast screening of genes and conditions that modulate folding. Likewise, such misfolding can be associated with protein mislocalization in the cell. Monitoring protein localization can, therefore, highlight changes in cellular folding capacity occurring in different tissues, at various stages of development and in the face of changing conditions. Finally, using biochemical tools ex vivo, we can directly monitor protein stability and conformation. Thus, by combining behavioral assays, imaging and biochemical techniques, we are able to monitor protein misfolding at the resolution of the organism, the cell, and the protein, respectively.

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

To study the relationship between protein homeostasis, stress and aging, we monitored changes in protein folding by following protein dysfunction, protein localization in the cell and protein stability at the organismal, cellular and protein levels, using the genetically tractable metazoan Caenorhabditis elegans as a model system.

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the ...

Visualization of Endoplasmic Reticulum Subdomains in Cultured Cells

The lipids and proteins in eukaryotic cells are continuously exchanged between cell compartments, although these retain their distinctive composition and functions despite the intense interorganelle molecular traffic. The techniques described in this paper are powerful means of studying protein and lipid mobility and trafficking in vivo and in their physiological environment. Fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP) are widely used live-cell imaging techniques for studying intracellular trafficking through the exo-endocytic pathway, the continuity between organelles or subcompartments, the formation of protein complexes, and protein localization in lipid microdomains, all of which can be observed under physiological and pathological conditions. The limitations of these approaches are mainly due to the use of fluorescent fusion proteins, and their potential drawbacks include artifactual over-expression in cells and the possibility of differences in the folding and localization of tagged and native proteins. Finally, as the limit of resolution of optical microscopy (about 200 nm) does not allow investigation of the fine structure of the ER or the specific subcompartments that can originate in cells under stress (i.e. hypoxia, drug administration, the over-expression of transmembrane ER resident proteins) or under pathological conditions, we combine live-cell imaging of cultured transfected cells with ultrastructural analyses based on transmission electron microscopy.

We describe the imaging approaches we use to investigate the distribution and mobility of the transfected fluorescent proteins resident in the endoplasmic reticulum (ER) by means of the confocal imaging of living cells. We also ultrastructurally analyze the effect of their expression on the architecture of this subcellular compartment.

Visualisation de réticulum endoplasmique sous-domaines dans les cellules cultivées

The lipids and proteins in eukaryotic cells are continuously exchanged between cell compartments, although these retain their distinctive composition and ...

Transfecting RAW264.7 Cells with a Luciferase Reporter Gene

Transfection of desired genetic materials into cells is an inevitable procedure in biomedical research studies. While numerous methods have been described, certain types of cells are resistant to many of these methods and yield low transfection efficiency1, potentially hindering research in those cell types. In this protocol, we present an optimized transfection procedure to introduce luciferase reporter genes as a plasmid DNA into the RAW264.7 macrophage cell line. Two different types of transfection reagents (lipid-based and polyamine-based) are described, and important notes are given throughout the protocol to ensure that the RAW264.7 cells are minimally altered by the transfection procedure and any experimental data obtained are the direct results of the experimental treatment. While transfection efficiency may not be higher compared to other transfection methods, the described procedure is robust enough for detecting luciferase signal in RAW264.7 without changing the physiological response of the cells to stimuli.

Transfection into the macrophage cell line, RAW264.7, is difficult due to the cell&#8217;s natural response against foreign materials. We described here a gentle yet robust procedure for transfecting luciferase reporter genes into RAW264.7 cells.

Transfecter des cellules RAW264.7 avec un gène rapporteur de la luciférase

Transfection of desired genetic materials into cells is an inevitable procedure in biomedical research studies. While numerous methods have been ...

Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging

Maintenance of steady-state calcium (Ca2+) levels in the sarcoplasmic reticulum (SR) of vascular smooth muscle cells (VSMCs) is vital to their overall health. A significant portion of intracellular Ca2+ content is found within the SR stores in VSMCs. As the only intracellular organelle with a close association to the surrounding extracellular space through plasma membrane-SR junctions, the SR can be considered to constitute the first line of response to any irregularity in Ca2+ transients, or stress experienced by the cell. Among its many functions, one of the most important is its role in the transmission of Ca2+-regulated signals throughout the cell to induce further cell-wide reactions downstream. The more common use of cytoplasmic Ca2+ indicators in this regard is overall insufficient for research into the highly dynamic changes to the intraluminal SR Ca2+ store that have yet to be fully characterized. Here, we provide a detailed protocol for the direct and clear measurement of luminal SR Ca2+. This tool is useful for investigation into the nuanced changes in SR Ca2+ that have significant subsequent effects on the normal function and health of the cell. Fluctuations in SR Ca2+ content specifically can provide us with a significant amount of information pertaining to cellular responses to disease or stress conditions experienced by the cell. In this method, a modified version of a SR-targeted Ca2+ indicator, D1SR, is used to detect Ca2+ fluctuations in response to the introduction of agents to cultured rat aortic smooth muscle cells (SMCs). Following incubation with the D1SR indicator, confocal fluorescence microscopy and fluorescence resonance energy transfer (FRET)-based imaging are used to directly observe changes to intraluminal SR Ca2+ levels under control conditions and with the addition of agonist agents that function to induce intracellular Ca2+ movement.

Currently, most available calcium indicators are used to quantify cytoplasmic calcium transients as indirect measures of calcium released from the sarcoplasmic reticulum in cultured smooth muscle cells. This protocol describes the use of a specific FRET-based indicator that allows direct measurement of calcium signals within the sarcoplasmic reticulum lumen.

Imagerie confocale à base de FRET mesure des fluctuations de calcium à l&#39;intérieur du réticulum sarcoplasmique de Cultured cellules musculaires lisses Utilisation

Maintenance of steady-state calcium (Ca2+) levels in the sarcoplasmic reticulum (SR) of vascular smooth muscle cells (VSMCs) is vital to their overall ...