Plásmido vinculina-GFP fue un regalo de Kenneth Yamada, Institutos Nacionales de Salud, Instituto Nacional de Investigación Dental y Craneofacial, Bethesda, Maryland, y la actina mRFP plásmido fue un regalo de Michael Davidson, Florida State University, Tallahassee, Florida. Este trabajo fue apoyado por el premio de su carrera NSF # 0747334 y AHA-Nacional SDG # 0835205N a Andreea Trache.

1. Panorámica del sistema de microscopio integrado El sistema de microscopio que se utiliza para estos estudios se ha descrito en detalle 1. En pocas palabras, un invertido Olympus IX-81 con microscopio TIRF adjunto (Olympus, Center Valley, PA) se combina con la CSU-22 Yokogawa cabeza de lectura (Yokogawa Electric Inc, Japón). Un microscopio de fuerza atómica Bioscope SZ (Veeco Instruments Inc, Santa Barbara, CA) está montado en la parte superior del microscopio invertido óptica, y todo el sistema se coloca en la parte superior de una tabla de grados de investigación óptica (Newport, Irvine, CA). El montaje confocal compuesta desde el escáner girar el disco, rueda de filtros externos y su cámara EMCCD (Roper Científico-Fotometría, Tucson, AZ) están rígidamente conectados con una placa base de aluminio colocado en una plataforma de silicio necesario para la amortiguación de las vibraciones. El escáner confocal se conecta con el microscopio a través de una brida con un collar de recauchutados que se puede separar de un microscopio AFM durante las mediciones, de tal manera que ninguna vibración del escáner girando el disco va a afectar a las mediciones de AFM. Un láser de argón-criptón (Spectra Physics, Mountain View, CA) se utiliza como fuente de excitación para ambos TIRF y modos de microscopía confocal, y se puede acoplar alternativamente en dos fibras ópticas que ofrecen el láser para la unión TIRF o el cabezal, respectivamente . Dos equipos de control del sistema: Slidebook software controla la formación de imágenes ópticas y software Nanoscope controla la AFM. 2. Cultivo de células Las células vivas que expresan GFP construcciones dirigidas contra las proteínas específicas se deben colocar en un plato con fondo de cristal de cultivo celular 24 horas antes de la prueba de estimulación mecánica. En el día del experimento sustituir el medio de cultivo celular con rojo fenol libre de soporte. La placa de cultivo celular se monta en la etapa de AFM con un collar magnético. 3. AFM Consejo Preparación y Microscopio Set-up La punta del AFM personalizar con una de 2 micrones biotinilado de perlas de vidrio se lavaron cinco veces con DPBS y luego se incubaron 5 minutos con avidina (1 mg / ml), se lavan nuevamente con DPBS cinco veces, y luego se incubaron 5 minutos con 1 mg / ml biotinilado fibronectina. La punta se lavaron cinco veces más en el extremo 2, montado en el escáner AFM, y luego la falda protectora de silicona se coloca alrededor de la titular. Ajuste el microscopio para ver vídeo para alinear la punta del AFM en el centro del campo de visión. Alinear la palanca óptica colocando el rayo láser en el extremo de la viga, y luego cambiar el objetivo a un objetivo de gran aumento adecuado de imágenes de células individuales. La constante del resorte de la punta tiene que ser determinada antes de comenzar el experimento. Este parámetro se mide utilizando el método de ajustar las características térmicas disponibles en el software Nanoscope. Interruptor de la cámara de vídeo a la cámara EMCCD para permitir la formación de imágenes de fluorescencia. A continuación, seleccione una celda y poner la punta del AFM en contacto con la celda en cuestión. Después de un tiempo de 20 minutos de espera, que es necesaria para una fuerte adhesión focal para formar en el punto de AFM de contacto con la superficie de la célula, el procedimiento de estimulación mecánica se inicia. 4. La estimulación mecánica de las células vivas TIRF 3-4 imagen será el método de elección para la visualización y cuantificación de las adhesiones focales, y girando el disco de imagen confocal 5 será utilizado para la visualización del citoesqueleto de actina a través del cuerpo celular. La AFM 6 se utilizará en el modo de imagen de contacto con el líquido. Una imagen TIRF o confocal de la célula se adquirió antes de iniciar el procedimiento de estimulación mecánica. La estimulación mecánica será inducida por la sonda de AFM funcionalizada que se mueve hacia arriba en pasos discretos cada 3-5 minutos durante un período de tiempo (1 a 1,5 horas). La célula reactiva de respuesta se grabará continuamente en software Nanoscope como una serie de imágenes de altura, cada línea de la imagen que representa una unidad de tiempo de 1 seg. Mientras que la adquisición de los datos de AFM, el operador controla en todo momento el z-posición de la punta del AFM para determinar el momento adecuado para la atracción de la próxima. Después de cada estimulación mecánica es posible adquirir una imagen TIRF o confocal de la celda en Slidebook software, mientras continua la adquisición de datos AFM. Las imágenes ópticas pueden ser procesados ​​off-line para crear películas que muestran la reorganización del citoesqueleto de actina y las adhesiones focales. Además, cada imagen puede ser procesada para determinar cuantitativamente área de la celda, la zona de proteínas específicas, y analizar la morfología de las células en general. Al final del experimento se retira la punta del AFM de la célula y la sensibilidad de la punta del AFM se medirá en el software Nanoscope. El experimento es muy sensible al ruido! Cualquier conversación o un microscopio de tocar durante la experiment debe ser evitado. Para minimizar el ruido en las mediciones de AFM, el confocal girar el disco debe ser disociado del microscopio. El tiempo de espera para formar una fuerte adhesión focal entre la superficie de la célula y la punta del AFM puede variar dependiendo del tipo de células utilizadas y el revestimiento de la matriz en la punta. 5. Resultados representante <img src="/files/ftp_upload/2072/2072fig1.jpg" alt="Figura 1" /> Figura 1. Mismas células del músculo liso vascular (CMLV) transfectadas con actina-mRFP y vinculina GFP-fue fotografiada por: (A) AFM en la superficie celular apical (B) TIRF en la superficie de células basales, y (C) girando el disco de microscopía confocal en todo el cuerpo de la célula. La imagen confocal se muestra como la proyección máxima de una pila de 3-D. Solapamientos entre las buenas y AFM TIRF o girar imágenes de disco confocal se muestran en (D) y (E), respectivamente. Tamaño de la imagen es de 64 x 50 micras. <img src="/files/ftp_upload/2072/2072fig2.jpg" alt="Figura 2" /> Figura 2. A las CMLV transfectadas con actina-mRFP fue estimulado mecánicamente por la AFM y la imagen haciendo girar el disco microscopía confocal Las flechas indican las fibras de actina que:. (A) polimerizar / espesar, (b) despolimerizar / desaparecer, o (c) paquete en conjunto debido a la reestructuración de la actina. Las líneas blancas discontinuas representan la punta del AFM encima de la celda. La imagen a tamaño 91 x 91 micras.

<ol>
	<li>Trache, A., Lim, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrated+microscopy+for+real-time+imaging+of+mechanotransduction+studies+in+live+cells.">Integrated microscopy for real-time imaging of mechanotransduction studies in live cells.</a> J Biomed Opt. 14, 034024-03 (2009).</li><li>Trache, A., Meininger, G. A., Coico, R., Kowalik, T., Quarles, J. M., Stevenson, B., Taylor, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+Force+Microscopy.">Atomic Force Microscopy.</a> Current Protocols in Microbiology. , 2.1-2.17 (2008).</li><li>Axelrod, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+imaging+of+surface+fluorescence+with+very+high+aperture+microscope+objectives.">Selective imaging of surface fluorescence with very high aperture microscope objectives.</a> J Biomed Opt. 6, 6-13 (2001).</li><li>Trache, A., Meininger, G. A., Coico, R., Kowalik, T., Quarles, J. M., Stevenson, B., Taylor, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Total+Internal+Reflection+Fluorescence+Microscopy.">Total Internal Reflection Fluorescence Microscopy.</a> Current Protocols in Microbiology. , 2.1-2.22 (2008).</li><li>Inoue, S., Inoue, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct-view+high-speed+confocal+scanner:+the+CSU-10.">Direct-view high-speed confocal scanner: the CSU-10.</a> Methods Cell Biol. 70, 87-127 (2002).</li><li>Binnig, G., Quate, C. F., Gerber, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+force+microscope.">Atomic force microscope.</a> Phys Rev Lett. 56, 930-933 (1986).</li><li>Stamenovi&#263;, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytoskeletal+mechanics+in+airway+smooth+muscle+cells.">Cytoskeletal mechanics in airway smooth muscle cells.</a> Respir Physiol Neurobiol. 163, 25-32 (2008).</li><li>Gunst, S. J., Tang, D. D., Opazo Saez, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytoskeletal+remodeling+of+the+airway+smooth+muscle+cell:+a+mechanism+for+adaptation+to+mechanical+forces+in+the+lung.">Cytoskeletal remodeling of the airway smooth muscle cell: a mechanism for adaptation to mechanical forces in the lung.</a> Respir Physiol Neurobiol. 137, 151-168 (2003).</li><li>Worth, N. F., Rolfe, B. E., Song, J., Campbell, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascular+smooth+muscle+cell+phenotypic+modulation+in+culture+is+associated+with+reorganization+of+contractile+and+cytoskeletal+proteins.">Vascular smooth muscle cell phenotypic modulation in culture is associated with reorganization of contractile and cytoskeletal proteins.</a> Cell Motility and the Cytoskeleton. 49, 130-145 (2001).</li><li>Romer, H. R., Birukov, K. G., Garcia, J. G. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focal+Adhesions:+paradigm+for+a+signaling+nexus.">Focal Adhesions: paradigm for a signaling nexus.</a> Circulation Research. 98, 606-616 (2006).</li><li>Opazo Saez, A., Zhang, W., Wu, Y., Turner, C. E., Tang, D. D., Gunst, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tension+development+during+contractile+stimulation+of+smooth+muscle+requires+recruitment+of+paxillin+and+vinculin+to+the+membrane.">Tension development during contractile stimulation of smooth muscle requires recruitment of paxillin and vinculin to the membrane.</a> Am J Physiol Cell Physiol. 286, C433-C447 (2004).</li><li>Alenghat, F. J., Ingber, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanotransduction:+all+signals+point+to+cytoskeleton,+matrix+and+integrins.">Mechanotransduction: all signals point to cytoskeleton, matrix and integrins.</a> Sciences STKE. 119, pe6-pe6 (2002).</li><li>Zamir, E., Geiger, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+complexity+and+dynamics+of+cell-matrix+adhesions.">Molecular complexity and dynamics of cell-matrix adhesions.</a> J Cell Sci. 114, 3583-3590 (2001).</li><li>Geiger, B., Bershdsky, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assembly+and+mechanosensory+function+of+focal+contacts.">Assembly and mechanosensory function of focal contacts.</a> Curr Opin Cell Biol. 13, 584-592 (2001).</li><li>Sastry, S. K., Burridge, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focal+Adhesions:+a+nexus+for+intracellular+signaling+and+cytoskeletal+dynamics.">Focal Adhesions: a nexus for intracellular signaling and cytoskeletal dynamics.</a> Exp Cell Res. 261, 25-36 (2000).</li><li>Orr, A. W., Helmke, B. P., Blackman, B. R., Schwartz, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+mechanotransduction.">Mechanisms of mechanotransduction.</a> Dev Cell. 10, 11-20 (2006).</li></ol>

Adherencias citoesqueleto 07.10 y focal 11-16 son estructuras dinámicas que reúnen, se dispersan y vuelta como las células migran o responder a la fuerza mecánica 17. Tienen funciones importantes en la regulación del crecimiento celular, la supervivencia, y la expresión génica. Conocer su distribución específica y la dinámica proporciona una mejor comprensión de cómo se comunican las células con la matriz y entre ellos. Este sistema nuevo microsc...

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">	
		
		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>AFM tip</td>
<td>&nbsp;</td>
<td>Novascan Technologies</td>
<td>&nbsp;</td>
<td>2 micron Borosilicate bead, 0.01N/m, Biotin Surface</td>
</tr>
<tr>
<td>avidin</td>
<td>&nbsp;</td>
<td>Sigma Aldrich</td>
<td>A9275</td>
<td>1mg/mL in DPBS</td>
</tr>
<tr>
<td>Fibronectin</td>
<td>&nbsp;</td>
<td>Sigma Aldrich</td>
<td>F4759</td>
<td>1 mg/mL</td>
</tr>
<tr>
<td>DPBS</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>21600-051</td>
<td>&nbsp;</td>
<tr>
<td>Amaxa transfection kit for Smooth Muscle Cells</td>
<td>&nbsp;</td>
<td>Lonza</td>
<td>VPI-1004</td>
<td>&nbsp;</td>
<tr>
<td>Mattek glass bottom dishes</td>
<td>&nbsp;</td>
<td>MatTek Corporation</td>
<td>P60G-1.5-30-F</td>
<td>Sterile 60mm Falcon dishes with glass bottom coverslip no. 1.5</td>
</tr>		</tbody>
		</table>
		</div>

live cell response to mechanical stimulation studied by integrated optical and atomic force microscopy

Para entender el mecanismo por el cual las células vivas sentido las fuerzas mecánicas, y cómo responden y se adaptan a su medio ambiente, una nueva tecnología capaz de investigar el comportamiento de las células a nivel subcelular con alta resolución espacial y temporal se ha desarrollado. Por lo tanto, un microscopio de fuerza atómica (AFM) se integró con la reflexión total interna de fluorescencia (TIRF) microscopía y el disco de giro rápido (FSD) microscopía confocal. El sistema integrado es ampliamente aplicable a través de una amplia gama de estudios moleculares dinámicos en cualquier célula viva adherente, permitiendo una imagen óptica directa de las respuestas celulares a la estimulación mecánica en tiempo real. Reorganización significativa de los filamentos de actina y adhesiones focales se demostró debido a la estimulación mecánica local en la superficie celular apical que los cambios inducidos en la estructura celular en todo el cuerpo celular. Estas técnicas innovadoras que proporcionan nueva información para la comprensión de la reestructuración de células vivas y dinámicas, en respuesta a una fuerza mecánica. Un protocolo detallado y un conjunto de datos representativos que muestran la respuesta de células vivas a la estimulación mecánica se presentan.

Watch this Scientific Journal Video about Live Cell Response to Mechanical Stimulation Studied by Integrated Optical and Atomic Force Microscopy at JoVE.com

Live Cell Response to Mechanical Stimulation Studied by Integrated Optical and Atomic Force Microscopy

Este documento tiene como objetivo instruir al lector en la operación de una fuerza integrada atómica microscopio óptico de imagen para la estimulación mecánica de las células vivas en la cultura. Un protocolo de paso a paso se presenta. Un conjunto representativo de datos que muestra la respuesta de células vivas a la estimulación mecánica se presenta.

Respuesta de células vivas a la estimulación mecánica estudiados por microscopía óptica integrada la Fuerza Atómica y

To understand the mechanism by which living cells sense mechanical forces, and how they respond and adapt to their environment, a new technology able to ...

live-cell-response-to-mechanical-stimulation-studied-integrated

Research

JoVE Journal

Biology

11.2K vistas.  Texas A&M Health Science Center. Este documento tiene como objetivo instruir al lector en la operación de una fuerza integrada atómica microscopio óptico de imagen para la estimulación mecánica de las células vivas en la cultura. Un protocolo de paso a paso se presenta. Un conjunto representativo de datos que muestra la respuesta de células vivas a la estimulación mecánica se presenta.

Video: Live Cell Response to Mechanical Stimulation Studied by Integrated Optical and Atomic Force Microscopy

Phase Contrast and Differential Interference Contrast (DIC) Microscopy

Phase-contrast microscopy is often used to produce contrast for transparent, non light-absorbing, biological specimens. The technique was discovered by Zernike, in 1942, who received the Nobel prize for his achievement. DIC microscopy, introduced in the late 1960s, has been popular in biomedical research because it highlights edges of specimen structural detail, provides high-resolution optical sections of thick specimens including tissue cells, eggs, and embryos and does not suffer from the  phase halos  typical of phase-contrast images. This protocol highlights the principles and practical applications of these microscopy techniques.

Phase Contrast and Differential Interference Contrast DIC Microscopy

This protocol highlights the principles and practical applications of Phase and Differential Interference Contrast (DIC) Microscopy

Contraste de fase y de interferencia diferencial microscopía de contraste (DIC)

Phase-contrast microscopy is often used to produce contrast for transparent, non light-absorbing, biological specimens. The technique was discovered by ...

Investigación

Biología

Presynaptically Silent Synapses Studied with Light Microscopy

Synaptic plasticity likely underlies the nervous system's ability to learn and remember and may also represent an adaptability that prevents otherwise damaging insults from becoming neurotoxic.  We have been studying a form of presynaptic plasticity that is interesting in part because it is expressed as a digital switching on and off of a presynaptic terminal s ability to release vesicles containing the neurotransmitter glutamate.  Here we demonstrate a protocol for visualizing the activity status of presynaptic terminals in dissociated cell cultures prepared from the rodent hippocampus.  The method relies on detecting active synapses using staining with a fixable form of the styryl dye FM1-43, commonly used to label synaptic vesicles.  This staining profile is compared with immunostaining of the same terminals with an antibody directed against the vesicular glutamate transporter 1 (vGluT-1), a stain designed to label all glutamate synapses regardless of activation status.   We find that depolarizing stimuli induce presynaptic silencing.  The population of synapses that is silent under baseline conditions can be activated by prolonged electrical silencing or by activation of cAMP signaling pathways.

Glutamatergic synapses can switch from an active mode to a silent mode. We demonstrate that presynaptic activity status in dissociated culture of rodent neurons is visualized using a fixable form of the FM1-43 dye to visualize active synapses and immunostaining with vGluT-1 antibody to visualize all glutamate synapses.

Las sinapsis silenciosa presináptico estudiado con microscopía de luz

Synaptic plasticity likely underlies the nervous system's ability to learn and remember and may also represent an adaptability that prevents otherwise ...

Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy

Matrix stiffness strongly influences growth, differentiation and function of adherent cells1-3. On the macro scale the stiffness of tissues and organs within the human body span several orders of magnitude4. Much less is known about how stiffness varies spatially within tissues, and what the scope and spatial scale of stiffness changes are in disease processes that result in tissue remodeling. To better understand how changes in matrix stiffness contribute to cellular physiology in health and disease, measurements of tissue stiffness obtained at a spatial scale relevant to resident cells are needed. This is particularly true for the lung, a highly compliant and elastic tissue in which matrix remodeling is a prominent feature in diseases such as asthma, emphysema, hypertension and fibrosis. To characterize the local mechanical environment of lung parenchyma at a spatial scale relevant to resident cells, we have developed methods to directly measure the local elastic properties of fresh murine lung tissue using atomic force microscopy (AFM) microindentation. With appropriate choice of AFM indentor, cantilever, and indentation depth, these methods allow measurements of local tissue shear modulus in parallel with phase contrast and fluorescence imaging of the region of interest. Systematic sampling of tissue strips provides maps of tissue mechanical properties that reveal local spatial variations in shear modulus. Correlations between mechanical properties and underlying anatomical and pathological features illustrate how stiffness varies with matrix deposition in fibrosis. These methods can be extended to other soft tissues and disease processes to reveal how local tissue mechanical properties vary across space and disease progression.

The stiffness of the extracellular matrix strongly influences multiple behaviors of adherent cells. Matrix stiffness varies spatially throughout a tissue, and undergoes modification in various disease conditions. Here we develop methods to characterize spatial variations in stiffness in normal and fibrotic mouse lung tissue using atomic force microscopy microindentation.

Micro-Mecánica Caracterización del tejido pulmonar con microscopía de fuerza atómica

Matrix stiffness strongly influences growth, differentiation and function of adherent cells1-3.  On the macro scale the stiffness of tissues and organs ...

Sample Preparation for Single Virion Atomic Force Microscopy and Super-resolution Fluorescence Imaging

Immobilization of virions to glass surfaces is a critical step in single virion imaging. Here we present a technique&#160;adopted from single molecule imaging assays which allows adhesion of single virions to glass surfaces with specificity. This preparation is based on grafting the surface of the glass with a mixture of PLL-g-PEG and PLL-g-PEG-Biotin, adding a layer of avidin, and finally creating virion anchors through attachment of biotinylated virus specific antibodies. We have applied this technique across a range of experiments including atomic force microscopy (AFM) and super-resolution fluorescence imaging. This sample preparation method results in a control adhesion of the virions to the surface.

The attachment of virions to a surface is a requirement for single virion imaging by Super-resolution fluorescence imaging or atomic force microscopy (AFM). Here we demonstrate a sample preparation method for controlled adhesion of virions to glass surfaces suitable for use in AFM and super-resolution fluorescence imaging.

Preparación de muestras para microscopía de fuerza atómica de virión único e imágenes de fluorescencia de súper resolución

Immobilization of virions to glass surfaces is a critical step in single virion imaging. Here we present a technique&#160;adopted from single molecule ...

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a versatile analytical tool for characterizing viscoelastic mechanical properties for a variety of materials ranging from hard (plastic, glass, metal, etc.) surfaces to cells on any substrate. It has been widely used to measure the stiffness of cells, but less frequently used to measure the stiffness of aortas. In this paper, we will describe the procedures for using AFM in contact mode to measure the ex vivo elastic modulus of unloaded mouse arteries. We describe our procedure for isolation of mouse aortas, and then provide detailed information for the AFM analysis. This includes step-by-step instructions for alignment of the laser beam, calibration of the spring constant and deflection sensitivity of the AFM probe, and acquisition of force curves. We also provide a detailed protocol for data analysis of the force curves.

Measuring the Stiffness of Ex Vivo Mouse Aortas Using Atomic Force Microscopy

We present detailed protocols for isolation of aortas from mouse and measurement of their elastic modulus using atomic force microscopy.

La medición de la rigidez de<em&gt; Ex Vivo</em&gt; Ratón aortas Usando microscopía de fuerza atómica

Arterial stiffening is a significant risk factor and biomarker for cardiovascular disease and a hallmark of aging. Atomic force microscopy (AFM) is a ...

Analyzing Cell Surface Adhesion Remodeling in Response to Mechanical Tension Using Magnetic Beads

Mechanosensitive cell surface adhesion complexes allow cells to sense the mechanical properties of their surroundings. Recent studies have identified both force-sensing molecules at adhesion sites, and force-dependent transcription factors that regulate lineage-specific gene expression and drive phenotypic outputs. However, the signaling networks converting mechanical tension into biochemical pathways have remained elusive. To explore the signaling pathways engaged upon mechanical tension applied to cell surface receptor, superparamagnetic microbeads can be used. Here we present a protocol for using magnetic beads to apply forces to cell surface adhesion proteins. Using this approach, it is possible to investigate not only force-dependent cytoplasmic signaling pathways by various biochemical approaches, but also adhesion remodeling by magnetic isolation of adhesion complexes attached to the ligand-coated beads. This protocol includes the preparation of ligand-coated superparamagnetic beads, and the application of define tensile forces followed by biochemical analyses. Additionally, we provide a representative sample of data demonstrating that tension applied to integrin-based adhesion triggers adhesion remodeling and alters protein tyrosine phosphorylation.

Cell surface adhesions are central in mechanotransduction, as they transmit mechanical tension and initiate the signaling pathways involved in tissue homeostasis and development. Here, we present a protocol for dissecting the biochemical pathways that are activated in response to tension, using ligand-coated magnetic microbeads and force application to adhesion receptors.

El análisis de la superficie celular Adhesión Remodeling en respuesta a la tensión mecánica usando perlas magnéticas

Mechanosensitive cell surface adhesion complexes allow cells to sense the mechanical properties of their surroundings. Recent studies have identified both ...

Glucose Uptake Measurement and Response to Insulin Stimulation in In Vitro Cultured Human Primary Myotubes

Skeletal muscle is the largest glucose deposit in mammals and largely contributes to glucose homeostasis. Assessment of insulin sensitivity of muscle cells is of major relevance for all studies dedicated to exploring muscle glucose metabolism and characterizing metabolic alterations. In muscle cells, glucose transporter type 4 (GLUT4) proteins translocate to the plasma membrane in response to insulin, thus allowing massive entry of glucose into the cell. The ability of muscle cells to respond to insulin by increasing the rate of glucose uptake is one of the standard readouts to quantify muscle cell sensitivity to insulin. Human primary myotubes are a suitable in vitro model, as the cells maintain many features of the donor phenotype, including insulin sensitivity. This in vitro model is also suitable for the test of any compounds that could impact insulin responsiveness. Measurements of the glucose uptake rate in differentiated myotubes reflect insulin sensitivity.
In this method, human primary muscle cells are cultured in vitro to obtain differentiated myotubes, and glucose uptake rates with and without insulin stimulation are measured. We provide a detailed protocol to quantify passive and active glucose transport rates using radiolabeled [3H] 2-deoxy-D-Glucose ([3H]2dG). Calculation methods are provided to quantify active basal and insulin-stimulated rates, as well as stimulation fold.

Glucose Uptake Measurement and Response to Insulin Stimulation in In Vitro Cultured Human Primary Myotubes

In this method, human primary muscle cells are cultured in vitro to obtain differentiated myotubes and glucose uptake rates are measured. We provide a detailed protocol to quantify rates in basal and insulin-stimulated states using radiolabeled [3H] 2-deoxy-D-Glucose.

Medición de la Absorción de Glucosa y Respuesta a la Estimulación de la Insulina en<em&gt; In Vitro</em&gt; Myotubes primario humano cultivado

Skeletal muscle is the largest glucose deposit in mammals and largely contributes to glucose homeostasis. Assessment of insulin sensitivity of muscle ...

Assessment of Dictyostelium discoideum Response to Acute Mechanical Stimulation

Chemotaxis, or migration up a gradient of a chemoattractant, is the best understood mode of directed migration. Studies using social amoeba Dictyostelium discoideum revealed that a complex signal transduction network of parallel pathways amplifies the response to chemoattractants, and leads to biased actin polymerization and protrusion of a pseudopod in the direction of a gradient. In contrast, molecular mechanisms driving other types of directed migration, for example, due to exposure to shear flow or electric fields, are not known. Many regulators of chemotaxis exhibit localization at the leading or lagging edge of a migrating cell, as well as show transient changes in localization or activation following global stimulation with a chemoattractant. To understand the molecular mechanisms of other types of directed migration we developed a method that allows examination of cellular response to acute mechanical stimulation based on brief (2 - 5 s) exposure to shear flow. This stimulation can be delivered in a channel while imaging cells expressing fluorescently-labeled biosensors to examine individual cell behavior. Additionally, cell population can be stimulated in a plate, lysed, and immunoblotted using antibodies that recognize active versions of proteins of interest. By combining both assays, one can examine a wide array of molecules activated by changes in subcellular localization and/or phosphorylation. Using this method we determined that acute mechanical stimulation triggers activation of the chemotactic signal transduction and actin cytoskeleton networks. The ability to examine cellular responses to acute mechanical stimulation is important for understanding the initiating events necessary for shear flow-induced motility. This approach also provides a tool for studying the chemotactic signal transduction network without the confounding influence of the chemoattractant receptor.

Assessment of Dictyostelium discoideum Response to Acute Mechanical Stimulation

Here we describe methods for assessing cellular response to acute mechanical stimulation. In the microscopy-based assay, we examine localization of fluorescently-labeled biosensors following brief stimulation with shear flow. We also test activation of various proteins of interest in response to acute mechanical stimulation biochemically.

Evaluación de Dictyostelium discoideum respuesta a estimulación mecánica aguda

Chemotaxis, or migration up a gradient of a chemoattractant, is the best understood mode of directed migration. Studies using social amoeba Dictyostelium ...

Protrusion Force Microscopy: A Method to Quantify Forces Developed by Cell Protrusions

In numerous biological contexts, animal cells need to interact physically with their environment by developing mechanical forces. Among these, traction forces have been well-characterized, but there is a lack of techniques allowing the measurement of the protrusion forces exerted by cells orthogonally to their substrate. We designed an experimental setup to measure the protrusion forces exerted by adherent cells on their substrate. Cells plated on a compliant Formvar sheet deform this substrate and the resulting topography is mapped by atomic force microscopy (AFM) at the nanometer scale. Force values are then extracted from an analysis of the deformation profile based on the geometry of the protrusive cellular structures. Hence, the forces exerted by the individual protruding units of a living cell can be measured over time. This technique will enable the study of force generation and its regulation in the many cellular processes involving protrusion. Here, we describe its application to measure the protrusive forces generated by podosomes formed by human macrophages.

Here, we detail the experimental techniques used to evaluate the protrusion forces that podosomes apply on a compliant film, from the preparation of the film to the automated analysis of topographical images.

Microscopia de la fuerza de protrusión: Un método para cuantificar las fuerzas desarrolladas por salientes de celular

In numerous biological contexts, animal cells need to interact physically with their environment by developing mechanical forces. Among these, traction ...

Characterizing Mechanical Properties of Primary Cell Wall in Living Plant Organs Using Atomic Force Microscopy

The mechanical properties of the primary cell walls determine the direction and rate of plant cell growth and, therefore, the future size and shape of the plant. Many sophisticated techniques have been developed to measure these properties; however, atomic force microscopy (AFM) remains the most convenient for studying cell wall elasticity at the cellular level. One of the most important limitations of this technique has been that only superficial or isolated living cells can be studied. Here, the use of atomic force microscopy to investigate the mechanical properties of primary cell walls belonging to the internal tissues of a plant body is presented. This protocol describes measurements of the apparent Young&#39;s modulus of cell walls in roots, but the method can also be applied to other plant organs. The measurements are performed on vibratome-derived sections of plant material in a liquid cell, which allows (i) avoiding the use of plasmolyzing solutions or sample impregnation with wax or resin, (ii) making the experiments fast, and (iii) preventing dehydration of the sample. Both anticlinal and periclinal cell walls can be studied, depending on how the specimen was sectioned. Differences in the mechanical properties of different tissues can be investigated in a single section. The protocol describes the principles of study planning, issues with specimen preparation and measurements, as well as the method of selecting force-deformation curves to avoid the influence of topography on the obtained values of elastic modulus. The method is not limited by sample size but is sensitive to cell size (i.e., cells with a large lumen are difficult to examine).

Studies of cell wall biomechanics are essential for understanding plant growth and morphogenesis. The following protocol is proposed to investigate thin primary cell walls in the internal tissues of young plant organs using atomic force microscopy.

Caracterización de las propiedades mecánicas de la pared celular primaria en órganos vegetales vivos mediante microscopía de fuerza atómica

The mechanical properties of the primary cell walls determine the direction and rate of plant cell growth and, therefore, the future size and shape of the ...