Este trabalho foi financiado por uma doação do Instituto Nacional de Saúde, Instituto Nacional de Diabetes e Doenças Digestivas e Renais, 2R01DK59558 (para GN). UAMS Translational Research Institute financiado pelos Institutos Nacionais de Saúde Centro Nacional de Pesquisa de Recursos concessão UL1 RR029884 financiou parcialmente Núcleo de Citometria de Fluxo no UAMS. Agradecemos ao Dr. Peipei Ping (Universidade da Califórnia em Los Angeles; Los Angeles, CA) para a prestação de uma alíquota de adenovírus carregando cDNA que codifica o negativo dominante (inativo) mutante da PKC-ε e Allen Dr. Samarel (Loyola University Medical Center; Maywood, IL) para proporcionar uma fracção de vector adenoviral que codifica o mutante constitutivamente activo da PKC-ε. Agradecemos também os drs. Peter Parker e Peter Sugden (Imperial College London, London, UK) para a prestação de codificação de cDNA constitutivamente ativos PKC ε.

<ol>
	<li>Nowak, G., Schnellmann, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+culture+conditions+stimulate+gluconeogenesis+in+primary+cultures+of+renal+proximal+tubule+cells.">Improved culture conditions stimulate gluconeogenesis in primary cultures of renal proximal tubule cells.</a> Am. J. Physiol. 268, C1053-C1061 (1995).</li><li>Nowak, G., Schnellmann, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=L-ascorbic+acid+regulates+growth+and+metabolism+of+renal+cells:+improvements+in+cell+culture.">L-ascorbic acid regulates growth and metabolism of renal cells: improvements in cell culture.</a> Am. J. Physiol. 271, 2072-2080 (1996).</li><li>Ping, P., Takano, H., Zhang, J., Tang, X. L., Qiu, Y., Li, R. C., Banerjee, S., Dawn, B., Balafonova, Z., Bolli, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isoform-selective+activation+of+protein+kinase+C+by+nitric+oxide+in+the+heart+of+conscious+rabbits:+a+signaling+mechanism+for+both+nitric+oxide-induced+and+ischemia-induced+preconditioning.">Isoform-selective activation of protein kinase C by nitric oxide in the heart of conscious rabbits: a signaling mechanism for both nitric oxide-induced and ischemia-induced preconditioning.</a> Circ. Res. 84, 587-604 (1999).</li><li>Wotton, D., Ways, D. K., Parker, P. J., Owen, 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=Activity+of+both+Raf+and+Ras+is+necessary+for+activation+of+transcription+of+the+human+T+cell+receptor+beta+gene+by+protein+kinase+C,+Ras+plays+multiple+roles.">Activity of both Raf and Ras is necessary for activation of transcription of the human T cell receptor beta gene by protein kinase C, Ras plays multiple roles.</a> J. Biol. Chem. 268, 17975-17982 (1993).</li><li>Nowak, G., Bakajsova, D., Samarel, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+kinase+C-&#949;+activation+induces+mitochondrial+dysfunction+and+fragmentation+in+renal+proximal+tubules.">Protein kinase C-&#949; activation induces mitochondrial dysfunction and fragmentation in renal proximal tubules.</a> Am. J. Physiol. Renal Physiol. 301, F197-F208 (2011).</li><li>Nowak, G., Clifton, G. L., Godwin, M. L., Bakajsova, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activation+of+ERK1/2+pathway+mediates+oxidant-induced+decreases+in+mitochondrial+function+in+renal+cells.">Activation of ERK1/2 pathway mediates oxidant-induced decreases in mitochondrial function in renal cells.</a> Am. J. Physiol. Renal Physiol. 291, 840-855 (2006).</li><li>Shaik, Z. P., Fifer, E. K., Nowak, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Akt+activation+improves+oxidative+phosphorylation+in+renal+proximal+tubular+cells+following+nephrotoxicant+injury.">Akt activation improves oxidative phosphorylation in renal proximal tubular cells following nephrotoxicant injury.</a> Am. J. Physiol. Renal Physiol. 294, F423-F432 (2008).</li><li>Nowak, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+kinase+C-&#945;+and+ERK1/2+mediate+mitochondrial+dysfunction,+decreases+in+active+Na++transport,+and+cisplatin-induced+apoptosis+in+renal+cells.">Protein kinase C-&#945; and ERK1/2 mediate mitochondrial dysfunction, decreases in active Na+ transport, and cisplatin-induced apoptosis in renal cells.</a> J. Biol. Chem. 277, 43377-43388 (2002).</li><li>Liu, X., Godwin, M. L., Nowak, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+kinase+C-+a+inhibits+the+repair+of+oxidative+phosphorylation+after+S-(1,2-dichlorovinyl)-L-cysteine+injury+in+renal+cells.">Protein kinase C- a inhibits the repair of oxidative phosphorylation after S-(1,2-dichlorovinyl)-L-cysteine injury in renal cells.</a> Am. J. Physiol. Renal Physiol. 287, F64-F73 (2004).</li><li>Nowak, G., Price, P. M., Schnellmann, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lack+of+a+functional+p21WAF1/CIP1+gene+accelerates+caspase-independent+apoptosis+induced+by+cisplatin+in+renal+cells.">Lack of a functional p21WAF1/CIP1 gene accelerates caspase-independent apoptosis induced by cisplatin in renal cells.</a> Am. J. Physiol. Renal Physiol. 285, F440-F450 (2003).</li><li>Cummings, B. S., Schnellmann, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cisplatin-induced+renal+cell+apoptosis:+caspase+3-dependent+and+-independent+pathways.">Cisplatin-induced renal cell apoptosis: caspase 3-dependent and -independent pathways.</a> J. Pharmacol. Exp. Ther. 302, 8-17 (2002).</li></ol>

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A abordagem aqui apresentada permite a super-expressão de isoenzimas individuais de PKC na cultura primária de células tubulares proximais renais. Há vários pontos fortes da presente abordagem: 1. Ela permite a investigação de mecanismos de regulação de uma população homogénea de células (células tubulares proximais renais) que são o alvo primário para vários insultos (isquemia, hipóxia, estresse oxidativo), drogas e nephrotoxicants dentro do rim. 2. Funções mitocondriais, neste modelo in vitro d...

<table border="1"><tbody><tr><td> Nome do reagente </td><td> Companhia </td><td> Número de catálogo </td></tr><tr><td> Câmara de fluxo laminar </td><td> Thermo Electron Corporation </td><td> FORMA 1104 </td></tr><tr><td> 2 ml e 15 ml moinho de tecidos Dounce </td><td> WHEATON </td><td> 989-24607, 357544 </td></tr><tr><td> 85 e 235 mícrons malha de nylon </td><td> Peças pequenas </td><td> CMN - 0085 - 10YD CMN - 0250 - 10YD </td></tr><tr><td> 50 ml tubo de centrífuga estéril </td><td> BIOLOGIX </td><td> BCT-P 50BS </td></tr><tr><td> 1,5 ml microtubo </td><td> Sarstedt </td><td> 72.690.001 </td></tr><tr><td> 35 x 10 milímetros placas de cultura estéreis </td><td> Corning </td><td> 430165 </td></tr><tr><td> Centrífuga Jouan </td><td> Jouan </td><td> Jouan CR3 11175704 Rotores: Jouan T40 </td></tr><tr&gt; <td> Centrífuga de micro-ajustável </td><td> SIGMA </td><td> Modelo 1-15 </td></tr><tr><td> Monitor de Oxigênio Biológica </td><td> YSI Incorporated </td><td> YSI modelo 5300A </td></tr><tr><td> Único sistema de câmara de oxigênio Micro </td><td> YSI Incorporated </td><td> 5356S </td></tr><tr><td> Sonda de oxigênio </td><td> YSI Incorporated </td><td> 5331A </td></tr><tr><td> Circulando Bath </td><td> YSI Incorporated </td><td> 5310 </td></tr><tr><td> KCl e kit de membrana padrão </td><td> YSI Incorporated </td><td> 5775 </td></tr><tr><td> Agitador magnético </td><td> YSI Incorporated </td><td> 5222 </td></tr><tr><td> Gravador de mesa </td><td> Kipp &amp; Zonen </td><td> BD 11E </td></tr><tr><td> De 48 poços e as placas de 96 poços transparentes </td><td> Costar </td><td> 3548, 3679 </td></tr><tr><td> R Thermomixer </td><td> Eppendorf </td><td> 5355 21919 </td></tr><tr><td> Orbital MAXQ 2000 </td><td> Thermo Scientific </td><td> SHKA 2000 </td></tr><tr><td> Spectra FLUOR Plus (absorbância fluorescência / / luminescência leitor) </td><td> Tecan </td><td> F129005 </td></tr><tr><td> Jaqueta de água EUA Autoflow automática incubadora de CO 2 </td><td> NuAire </td><td> NU 4850 </td></tr><tr><td> Cultura de poliestireno de 12x75 mm para tubos de ensaio de citometria de fluxo </td><td> Fisher Marca </td><td> 14-961-20 </td></tr><tr><td> Axioskop Objetiva de imersão de água 63x / 0,90 W </td><td> Carl Zeiss </td><td> 114846 ACHROPLAN 44 00 67 </td></tr><tr><td> DMEM / F12 </td><td> Cellgro </td><td> 99-830 - PB </td></tr><tr><td> DMEM / Ham F12 </td><td> Sigma </td><td> D 2906 - 1L </td></tr><tr><td> Mesilato deferoxamina </td><td> Hospira </td><td> D110 </td></tr><tr><td> Colagenase tipo I </td><td> Worthington </td><td> 4196 </td></tr><tr><td> Inibidor de tripsina </td><td> Sigma </td><td> T 6522 - 500mg </td></tr><tr><td> 5,5 &#39;, 6,6&#39;-tetracloro-1, 1 &#39;, 3,3&#39;-tetraethylbenzimidazolylcarbocyanine iodeto (JC-1) </td><td> Invitrogen </td><td> T3168 </td></tr><tr><td> Mitotracker Vermelho </td><td> Invitrogen </td><td> M22425 </td></tr><tr><td> A bioluminescência ATP Ensaio Kit HS II </td><td> Roche </td><td> 11 699 709 001 </td></tr><tr><td> Anexina V - solução FITC </td><td> BioVision </td><td> 1001 - 200 </td></tr><tr><td> Citómetro </td><td> BD Biosciences </td><td> BD FACSCalibur </td></tr></tbody></table>

assessment of mitochondrial functions and cell viability in renal cells overexpressing protein kinase c isozymes

A proteína quinase C de família (PKC) de isoenzimas está envolvido em vários processos fisiológicos e patológicos. Nossos dados recentes demonstram que PKC regula a função mitocondrial e energético celular. Numerosos relatos demonstraram que a activação de PKC-a e PKC-ε melhora a função mitocondrial do coração isquémica e medeia cardioprotecção. Em contraste, nós demonstramos que a PKC-α e PKC-ε estão envolvidos na nephrotoxicant induzida disfunção mitocondrial e morte celular em células de rim. Portanto, o objetivo deste estudo foi desenvolver um modelo in vitro de células renais mantendo ativa as funções mitocondriais em que isozimas PKC poderia ser seletivamente ativadas ou inibidas para determinar seu papel na regulação da fosforilação oxidativa e sobrevivência celular. As culturas primárias de células tubulares proximais renais (RPTC) foram cultivadas em condições melhoradas, resultando em respiração mitocondrial e atividade de mitoenzimas mitocondrial semelhantes aos descritos no RPTC in vivo. Porque as técnicas de transfecção tradicionais (Lipofectamine, electroporação) são ineficientes em culturas primárias e têm efeitos adversos sobre a função mitocondrial, PKC-ε cDNAs mutantes foram entregues a RPTC através vectores adenovirais. Esta abordagem resulta em transfecção de mais de 90% RPTC culta. Aqui, apresentamos métodos para avaliar o papel da PKC-ε em: 1. regulação da morfologia mitocondrial e funções associadas com a síntese de ATP, e 2. sobrevivência de RPTC em cultura primária. PKC-ε é ativado pela superexpressão da constitutivamente ativa PKC-ε mutante. PKC-ε é inibida por superexpressam o mutante inactivo do ε-PKC. A função mitocondrial é avaliada examinando-se a respiração, a integridade da cadeia respiratória, as actividades dos complexos respiratórios e F 0 F 1-ATPase, a taxa de produção de ATP, e teor de ATP. A respiração é umssessed em digitonina-permeabilizadas RPTC como o estado 3 (respiração máxima na presença de substratos em excesso e ADP) e respiração desacoplados. Integridade da cadeia respiratória é avaliada por medição das actividades de todos os quatro complexos da cadeia respiratória nas mitocôndrias isoladas. Capacidade de fosforilação oxidativa é avaliada através da medição do potencial de membrana mitocondrial, a taxa de produção de ATP, e a actividade de F 0 F 1-ATPase. Estado de energia RPTC é avaliada através da determinação do teor de ATP intracelular. Morfologia mitocondrial em células vivas é visualizada utilizando MitoTracker Red 580, um corante fluorescente que se acumula especificamente nas mitocondrias, e monocamadas vivas são examinados sob um microscópio fluorescente. Viabilidade RPTC é avaliada através de anexina V / coloração com iodeto de propídio seguido por citometria de fluxo para determinar a apoptose e oncose. Estes métodos permitem uma activação selectiva / inibição do indivíduo isozimas PKCpara avaliar o seu papel em funções celulares de uma variedade de condições fisiológicas e patológicas que podem ser reproduzidas em in vitro.

A Figura 1 mostra que a entrega adenoviral de cDNA que codifica os constitutivamente activas (caPKC-ε) e inactivos (dnPKC-ε ε) mutantes de-PKC resulta em níveis significativamente aumentados de proteínas ε-PKC em RPTC e na mitocôndria. As células infectadas com o vector de transporte cDNA caPKC ε-superexpresso a forma (activo) fosforilada da PKC-ε enquanto que as células infectadas com o cDNA que codifica sobreexpressa dnPKC-ε ε-PKC que era inactiva (não fosforilado) (Figura 1).</s...

Watch this Scientific Journal Video about Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes at JoVE.com

Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes

Os efeitos da activação da proteína quinase C (PKC) isozimas de funções mitocondriais associadas com a respiração e fosforilação oxidativa e na viabilidade celular são descritos. A abordagem técnica adapta adenoviral para superexpressar selectivamente as isozimas PKC em cultura primária de células e uma variedade de ensaios para determinar as funções mitocondriais e do estado de energia da célula.

Avaliação de funções mitocondriais e viabilidade celular em células renais Proteína Kinase C superexpressão Isozimas

The protein kinase C (PKC) family of isozymes is involved in numerous physiological and pathological processes. Our recent data demonstrate that PKC ...

assessment-mitochondrial-functions-cell-viability-renal-cells

Research

JoVE Journal

Biology

18.1K visualizações.  University of Arkansas for Medical Sciences. Os efeitos da activação da proteína quinase C (PKC) isozimas de funções mitocondriais associadas com a respiração e fosforilação oxidativa e na viabilidade celular são descritos. A abordagem técnica adapta adenoviral para superexpressar selectivamente as isozimas PKC em cultura primária de células e uma variedade de ensaios para determinar as funções mitocondriais e do estado de energia da célula.

Vídeo: Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes

Counting and Determining the Viability of Cultured Cells

Determining the number of cells in culture is important in standardization of culture conditions and in performing accurate quantitation experiments. A hemacytometer is a thick glass slide with a central area designed as a counting chamber. Cell suspension is applied to a defined area and counted so cell density can be calculated. 

Determining the number of cells in culture is important in standardization of culture conditions and in performing accurate quantitation experiments. In this video, we demonstrate how cells are counted using a hemacytometer.

Contagem e determinação da viabilidade das células em cultura

Determining the number of cells in culture is important in standardization of culture conditions and in performing accurate quantitation experiments. A ...

Biologia

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.

Ativação da apoptose por microinjeção citoplasmática de citocromo C</em

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

Assessment of GFP Expression and Viability Using the Tali Image-Based Cytometer

Single-cell and population information are commonly obtained either by flow cytometry or fluorescence microscopy. However, these two methods provide different information. Flow cytometry gives quantitative multi-parametric information about physical characteristics and staining or expression, but doesn't allow for visualization. Stand-alone fluorescence microscopy provides visual data, but doesn't allow for straightforward quantitative measurements1.
Image-based cytometry bridges the gap between these two methods, enabling the quick visualization and simultaneous quantitative analysis of thousands of cells in heterogeneous populations2. Here, we present a method for performing cell viability and green fluorescent protein (GFP) expression assays using the Tali Image-Based Cytometer3. The Tali instrument is a 3-channel (bright field, green fluorescence, red fluorescence) benchtop assay platform that offers several advantages over flow cytometry and fluorescence microscopy. The Tali cytometer is less expensive, takes up less bench space, requires less maintenance, and the work flow has been simplified so that the operation and analysis is much simpler and quicker. The Tali cytometer is capable of performing a range of suspension cell-based assays, including GFP and red fluorescent protein (RFP) expression, apoptosis4-6 and cell viability analysis with propidium iodide (PI)7-11.
Here, we demonstrate the use of the Tali instrument in performing a cell viability assay in cells expressing GFP. GFP-transduced cells are stained using the Tali Viability Kit - Dead Cell Red. The cells are then pipetted into a Tali Cellular Analysis Slide and loaded into the cytometer. Bright field, red fluorescence and green fluorescence images are captured and analyzed using assay specific algorithms. Histograms are then generated to display cell size, PI fluorescence intensity, and GFP fluorescence intensity. These parameters can then be thresholded to home in on a specific cell population.
A side-by side comparison of the Tali Image-Based Cytometer and traditional flow cytometry demonstrates that the two methods provide comparable data regarding cell viability and protein expression. However, the Tali instrument provides additional visual information about the cell population that cannot be obtained using a flow cytometer.

This protocol describes how to perform cell viability and fluorescence expression assays using the Tali Image-Based Cytometer.

Avaliação da GFP Expressão e Viabilidade Usando o Tali Citómetro Baseado na Imagem

Single-cell and population information are commonly obtained either by flow cytometry or fluorescence microscopy. However, these two methods provide ...

4D Imaging of Protein Aggregation in Live Cells

One of the key tasks of any living cell is maintaining the proper folding of newly synthesized proteins in the face of ever-changing environmental conditions and an intracellular environment that is tightly packed, sticky, and hazardous to protein stability1. The ability to dynamically balance protein production, folding and degradation demands highly-specialized quality control machinery, whose absolute necessity is observed best when it malfunctions. Diseases such as ALS, Alzheimer's, Parkinson's, and certain forms of Cystic Fibrosis have a direct link to protein folding quality control components2, and therefore future therapeutic development requires a basic understanding of underlying processes. Our experimental challenge is to understand how cells integrate damage signals and mount responses that are tailored to diverse circumstances.
The primary reason why protein misfolding represents an existential threat to the cell is the propensity of incorrectly folded proteins to aggregate, thus causing a global perturbation of the crowded and delicate intracellular folding environment1. The folding health, or "proteostasis," of the cellular proteome is maintained, even under the duress of aging, stress and oxidative damage, by the coordinated action of different mechanistic units in an elaborate quality control system3,4. A specialized machinery of molecular chaperones can bind non-native polypeptides and promote their folding into the native state1, target them for degradation by the ubiquitin-proteasome system5, or direct them to protective aggregation inclusions6-9.
In eukaryotes, the cytosolic aggregation quality control load is partitioned between two compartments8-10: the juxtanuclear quality control compartment (JUNQ) and the insoluble protein deposit (IPOD) (Figure 1 - model). Proteins that are ubiquitinated by the protein folding quality control machinery are delivered to the JUNQ, where they are processed for degradation by the proteasome. Misfolded proteins that are not ubiquitinated are diverted to the IPOD, where they are actively aggregated in a protective compartment.
Up until this point, the methodological paradigm of live-cell fluorescence microscopy has largely been to label proteins and track their locations in the cell at specific time-points and usually in two dimensions. As new technologies have begun to grant experimenters unprecedented access to the submicron scale in living cells, the dynamic architecture of the cytosol has come into view as a challenging new frontier for experimental characterization. We present a method for rapidly monitoring the 3D spatial distributions of multiple fluorescently labeled proteins in the yeast cytosol over time. 3D timelapse (4D imaging) is not merely a technical challenge; rather, it also facilitates a dramatic shift in the conceptual framework used to analyze cellular structure.
We utilize a cytosolic folding sensor protein in live yeast to visualize distinct fates for misfolded proteins in cellular aggregation quality control, using rapid 4D fluorescent imaging. The temperature sensitive mutant of the Ubc9 protein10-12 (Ubc9ts) is extremely effective both as a sensor of cellular proteostasis, and a physiological model for tracking aggregation quality control. As with most ts proteins, Ubc9ts is fully folded and functional at permissive temperatures due to active cellular chaperones. Above 30 &deg;C, or when the cell faces misfolding stress, Ubc9ts misfolds and follows the fate of a native globular protein that has been misfolded due to mutation, heat denaturation, or oxidative damage. By fusing it to GFP or other fluorophores, it can be tracked in 3D as it forms Stress Foci, or is directed to JUNQ or IPOD.

Cellular viability depends on timely and efficient management of protein misfolding. Here we describe a method for visualizing the different potential fates of a misfolded protein: refolding, degradation, or sequestration in inclusions. We demonstrate the use of a folding sensor, Ubc9ts, for monitoring proteostasis and aggregation quality control in live cells using 4D microscopy.

Formação de imagens 4D de agregação de proteínas em células vivas

One of the key tasks of any living cell is maintaining the proper folding of newly synthesized proteins in the face of ever-changing environmental ...

Viability Assays for Cells in Culture

Manual cell counts on a microscope are a sensitive means of assessing cellular viability but are time-consuming and therefore expensive. Computerized viability assays are expensive in terms of equipment but can be faster and more objective than manual cell counts. The present report describes the use of three such viability assays. Two of these assays are infrared and one is luminescent. Both infrared assays rely on a 16&#160;bit Odyssey Imager. One infrared assay uses the DRAQ5 stain for nuclei combined with the Sapphire stain for cytosol and is visualized in the 700 nm channel. The other infrared assay, an In-Cell Western, uses antibodies against cytoskeletal proteins (&#945;-tubulin or microtubule associated protein 2) and labels them in the 800 nm channel. The third viability assay is a commonly used luminescent assay for ATP, but we use a quarter of the recommended volume to save on cost. These measurements are all linear and correlate with the number of cells plated, but vary in sensitivity. All three assays circumvent time-consuming microscopy and sample the entire well, thereby reducing sampling error. Finally, all of the assays can easily be completed within one day of the end of the experiment, allowing greater numbers of experiments to be performed within short timeframes. However, they all rely on the assumption that cell numbers remain in proportion to signal strength after treatments, an assumption that is sometimes not met, especially for cellular ATP. Furthermore, if cells increase or decrease in size after treatment, this might affect signal strength without affecting cell number. We conclude that all viability assays, including manual counts, suffer from a number of caveats, but that computerized viability assays are well worth the initial investment. Using all three assays together yields a comprehensive view of cellular structure and function.

Therapeutic compounds are often first examined in vitro with viability assays. Blind cell counts by a human observer can be highly sensitive to small changes in cell number but do not assess function. Computerized viability assays, as described here, can assess both structure and function in an objective manner.

Ensaios de viabilidade para células em cultura

Manual cell counts on a microscope are a sensitive means of assessing cellular viability but are time-consuming and therefore expensive. Computerized ...

Experimental Approaches to Study Mitochondrial Localization and Function of a Nuclear Cell Cycle Kinase, Cdk1

Although mitochondria possess their own transcriptional machinery, merely 1% of mitochondrial proteins are synthesized inside the organelle. The nuclear-encoded proteins are transported into mitochondria guided by their mitochondria targeting sequences (MTS); however, a majority of mitochondrial localized proteins lack an identifiable MTS. Nevertheless, the fact that MTS can instruct proteins to go into the mitochondria provides a valuable tool for studying mitochondrial functions of normally nuclear and/or cytoplasmic proteins. We have recently identified the cell cycle kinase CyclinB1/Cdk1 complex in the mitochondria. To specifically study the mitochondrial functions of this complex, mitochondrial overexpression and knock-down of this complex without interfering with its nuclear or cytoplasmic functions were essential. By tagging CyclinB1/Cdk1 with MTS, we were able to achieve mitochondrial overexpression of this complex to study its mitochondrial targets as well as functions. Via tagging dominant-negative Cdk1 with MTS, inhibition of Cdk1 activity was accomplished particularly in the mitochondria. Potential mitochondrial targets of CyclinB1/Cdk1 complex were identified using a gel-based proteomics approach. Unlike traditional 2D gel analysis, we employed 2-dimensional difference gel electrophoresis (2D-DIGE) technology followed by phosphoprotein staining to fluorescently label differentially phosphorylated proteins in mitochondrial Cdk1 expressing cells. Identification of phosphoprotein spots that were altered in wild type versus dominant negative Cdk1 bearing mitochondria revealed the identity of mitochondrial targets of Cdk1. Finally, to determine the effect of CyclinB1/Cdk1 mitochondrial localization in cell cycle progression, a cell proliferation assay using a synthetic thymidine analogue EdU (5-ethynyl-2&#8242;-deoxyuridine) was used to monitor the cells as they go through the cell cycle and replicate their DNA. Altogether, we demonstrated a variety of approaches available to study mitochondrial localization and activity of a cell cycle kinase. These are advanced, yet easy to follow methods that will be beneficial to many cell biology researchers.

Here, we outline how to study mitochondrial localization of a (cell cycle) kinase, and how to determine its sub-mitochondrial location as well as potential mitochondrial substrates/targets. Forced expression of proteins into the mitochondria provides a useful tool for studying the functional consequences of mitochondrial localization of a protein of interest.

Abordagens experimentais para estudar mitocondrial Localização e função de um ciclo celular Nuclear Kinase, Cdk1

Although mitochondria possess their own transcriptional machinery, merely 1% of mitochondrial proteins are synthesized inside the organelle. The ...

Simultaneous Measurement of Mitochondrial Calcium and Mitochondrial Membrane Potential in Live Cells by Fluorescent Microscopy

Apart from their essential role in generating ATP, mitochondria also act as local calcium (Ca2+) buffers to tightly regulate intracellular Ca2+ concentration. To do this, mitochondria utilize the electrochemical potential across their inner membrane (&#916;&#936;m) to sequester Ca2+. The influx of Ca2+ into the mitochondria stimulates three rate-limiting dehydrogenases of the citric acid cycle, increasing electron transfer through the oxidative phosphorylation (OXPHOS) complexes. This stimulation maintains &#916;&#936;m, which is temporarily dissipated as the positive calcium ions cross the mitochondrial inner membrane into the mitochondrial matrix.
We describe here a method for simultaneously measuring mitochondria Ca2+ uptake and &#916;&#936;m in live cells using confocal microscopy. By permeabilizing the cells, mitochondrial Ca2+ can be measured using the fluorescent Ca2+ indicator Fluo-4, AM, with measurement of &#916;&#936;m using the fluorescent dye tetramethylrhodamine, methyl ester, perchlorate (TMRM). The benefit of this system is that there is very little spectral overlap between the fluorescent dyes, allowing accurate measurement of mitochondrial Ca2+ and &#916;&#936;m simultaneously. Using the sequential addition of Ca2+ aliquots, mitochondrial Ca2+ uptake can be monitored, and the concentration at which Ca2+ induces mitochondrial membrane permeability transition and the loss of &#916;&#936;m determined.

Mitochondria can utilize the electrochemical potential across their inner membrane (&#916;&#936;m) to sequester calcium (Ca2+), allowing them to shape cytosolic Ca2+ signaling within the cell. We describe a method for simultaneously measuring mitochondria Ca2+ uptake and &#916;&#936;m in live cells using fluorescent dyes and confocal microscopy.

Medição simultânea de mitocondrial de cálcio e mitocondrial potencial de membrana em células vivas por Microscopia fluorescente

Apart from their essential role in generating ATP, mitochondria also act as local calcium (Ca2+) buffers to tightly regulate intracellular Ca2+ ...

A Graphical User Interface for Software-assisted Tracking of Protein Concentration in Dynamic Cellular Protrusions

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex signaling mechanisms underlying filopodial initiation, elongation and subsequent stabilization or retraction, it is crucial to determine the spatio-temporal protein activity in these dynamic structures. To analyze protein function in filopodia, we recently developed a semi-automated tracking algorithm that adapts to filopodial shape-changes, thus allowing parallel analysis of protrusion dynamics and relative protein concentration along the whole filopodial length. Here, we present a detailed step-by-step protocol for optimized cell handling, image acquisition and software analysis. We further provide instructions for the use of optional features during image analysis and data representation, as well as troubleshooting guidelines for all critical steps along the way. Finally, we also include a comparison of the described image analysis software with other programs available for filopodia quantification. Together, the presented protocol provides a framework for accurate analysis of protein dynamics in filopodial protrusions using image analysis software.

We present a software solution for semi-automated tracking of relative protein concentration along the length of dynamic cellular protrusions.

Uma interface de usuário gráfica para rastreamento assistido por software da concentração de proteínas em protrusões celulares dinâmicas

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex ...

Primary Culture of Rat Adrenocortical Cells and Assays of Steroidogenic Functions

The hormone which the adrenal cortex secretes is vital for animals against stress and diseases. The method described here is the procedure of primary cultured rat adrenal cells and related functional assays (immunofluorescence staining of lipid droplet surface protein, as well as corticosterone analysis). Unlike an in vivo model, the variation of interexperiments in adrenal monolayer cultures is less and the experimental condition is easy to control. Besides, the source of rats is also more stable than other animals, like bovine ones. There are also several human adrenal cell lines (NCI-H295, NCI-H295R, SW13, etc.) that can be used in adrenal studies. However, the steroid production of these lines will still be influenced by numerous factors, which include serum lot number, passage number, mutant/loss of distinct genes, etc. Except for lacking 17&#945;-hydroxylase, the primary culture of rat adrenocortical cells is a better and more convenient technique for studying adrenal physiology. In summary, primary rat adrenal cultures could be a good in vitro platform for researchers to investigate the mechanisms of the reagent of interest in the adrenal gland system.

The hormone secreted by the adrenal cortex is vital for animals against stress and diseases. Here, we present a protocol to culture the primary rat adrenal cells. It could be a good in vitro platform for investigating the mechanisms of the reagent of interest in adrenal steroidogenesis and lipid biosynthesis.

Cultura primária de células Adrenocortical rato e ensaios das funções reguladora

The hormone which the adrenal cortex secretes is vital for animals against stress and diseases. The method described here is the procedure of primary ...

Photostimulation by Femtosecond Laser Activates Extracellular-signal-regulated Kinase (ERK) Signaling or Mitochondrial Events in Target Cells

Direct control of cellular defined molecular events is important to life science. Recently, studies have demonstrated that femtosecond laser stimulation can simultaneously activate multiple cellular molecular signaling pathways. In this protocol, we show that through coupling femtosecond laser into a confocal microscope, cells can be stimulated precisely by the tightly-focused laser. Some molecular processes that can be simultaneously observed are subsequently activated. We present detailed protocols of the photostimulation to activate extracellular signal regulated kinase (ERK) signaling pathway in Hela cells. Mitochondrial flashes of reactive oxygen species (ROS) and other mitochondrial events can be also stimulated if focusing the femtosecond laser pulse on a certain mitochondrial tubular structure. This protocol includes pretreating cells before photostimulation, delivering the photostimulation by a femtosecond laser flash onto the target, and observing/identifying molecular changes afterwards. This protocol represents an all-optical tool for related biological researches.

Photostimulation by Femtosecond Laser Activates Extracellular-signal-regulated Kinase ERK Signaling or Mitochondrial Events in Target Cells

Tightly-focused femtosecond laser can deliver precise stimulation to cells by being coupled into a confocal microscopy enabling the real-time observation and photostimulation. The photostimulation can activate cell molecular events including ERK signaling pathway and mitochondrial flashes of reactive oxygen species.

Fotoestimulação por Femtosecond laser ativa extracellular-sinal-regulado quinase (ERK) sinalização ou eventos mitocondrial em células-alvo

Direct control of cellular defined molecular events is important to life science. Recently, studies have demonstrated that femtosecond laser stimulation ...