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1. Two-Layer Elastographic 3-D Traction Force Microscopy.

Author

Álvarez-González, Begoña, Zhang, Shun, Gómez-González, Manuel, Meili, Ruedi, Firtel, Richard A, Lasheras, Juan C, and Del Álamo, Juan C

Subjects
Physarum, Imaging, Three-Dimensional, Microscopy, Atomic Force, Traction, Imaging, Three-Dimensional, Microscopy, Atomic Force
Abstract

Cellular traction force microscopy (TFM) requires knowledge of the mechanical properties of the substratum where the cells adhere to calculate cell-generated forces from measurements of substratum deformation. Polymer-based hydrogels are broadly used for TFM due to their linearly elastic behavior in the range of measured deformations. However, the calculated stresses, particularly their spatial patterns, can be highly sensitive to the substratum's Poisson's ratio. We present two-layer elastographic TFM (2LETFM), a method that allows for simultaneously measuring the Poisson's ratio of the substratum while also determining the cell-generated forces. The new method exploits the analytical solution of the elastostatic equation and deformation measurements from two layers of the substratum. We perform an in silico analysis of 2LETFM concluding that this technique is robust with respect to TFM experimental parameters, and remains accurate even for noisy measurement data. We also provide experimental proof of principle of 2LETFM by simultaneously measuring the stresses exerted by migrating Physarum amoeboae on the surface of polyacrylamide substrata, and the Poisson's ratio of the substrata. The 2LETFM method could be generalized to concurrently determine the mechanical properties and cell-generated forces in more physiologically relevant extracellular environments, opening new possibilities to study cell-matrix interactions.

Published
2017

2. Distribution of Traction Forces and Intracellular Markers Associated with Shape Changes During Amoeboid Cell Migration

Author

Lasheras, Juan C., Alonso-Latorre, BaLdomeRo, Meili, Ruedi, Bastounis, Effie, del Alamo, Juan C., and Firtel, Richard A.

Subjects
Quantitative Biology - Cell Behavior, Quantitative Biology - Quantitative Methods
Abstract

During migration, amoeboid cells perform a cycle of quasi-periodic repetitive events (motility cycle). the cell length and the strain energy exchanged with the substrate oscillate in time with an average frequency, f, on top of which are imposed smaller random fluctuations. the fact that a considerable portion of the changes in cell shape are due to periodic repetitive events enables the use of conditional statistics methods to analyze the network of biochemical processes involved in cell motility. taking advan- tage of this cyclic nature, we apply Principal Component analysis (PCa) and phase- average statistics to analyze the dominant modes of shape change and their association to the activity and localization of molecular motors. We analyze time-lapse measure- ments of cell shape, traction forces and fluorescence from green fluorescent protein (GfP) reporters for f-actin in Dictyostelium cells undergoing guided chemotactic migration. using wild-type cells (wt) as reference, we investigated the contractile and actin crosslinking functions of myosin II by studying myosin II heavy chain null mutant cells (mhcA-) and myosin II essential light chain null cells (mlcE-)., Comment: Conference Paper for the Sixth Interdisciplinary Transport Phenomena Conference: Fluid, Thermal, Biological, Materials and Space Sciences. Volterra. Italy. October 4-9, (2009)

Published
2013

3. Three-Dimensional Quantification of Cellular Traction Forces and Mechanosensing of Thin Substrata by Fourier Traction Force Microscopy

Author

del Alamo, Juan C, Meili, Ruedi, Alvarez-Gonzalez, Begoña, Alonso-Latorre, Baldomero, Bastounis, Effie, Firtel, Richard, and Lasheras, Juan C

Subjects
Quantitative Biology - Quantitative Methods, Condensed Matter - Soft Condensed Matter, Quantitative Biology - Cell Behavior
Abstract

We introduce a novel three-dimensional (3D) traction force microscopy (TFM) method motivated by the recent discovery that cells adhering on plane surfaces exert both in-plane and out-of-plane traction stresses. We measure the 3D deformation of the substratum on a thin layer near its surface, and input this information into an exact analytical solution of the elastic equilibrium equation. These operations are performed in the Fourier domain with high computational efficiency, allowing to obtain the 3D traction stresses from raw microscopy images virtually in real time. We also characterize the error of previous two-dimensional (2D) TFM methods that neglect the out-of-plane component of the traction stresses. This analysis reveals that, under certain combinations of experimental parameters (\ie cell size, substratums' thickness and Poisson's ratio), the accuracy of 2D TFM methods is minimally affected by neglecting the out-of-plane component of the traction stresses. Finally, we consider the cell's mechanosensing of substratum thickness by 3D traction stresses, finding that, when cells adhere on thin substrata, their out-of-plane traction stresses can reach four times deeper into the substratum than their in-plane traction stresses. It is also found that the substratum stiffness sensed by applying out-of-plane traction stresses may be up to 10 times larger than the stiffness sensed by applying in-plane traction stresses.

Published
2013
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9. Spatio-temporal analysis of eukaryotic cell motility by improved force cytometry

Author

del Alamo, Juan C., Meili, Ruedi, Alonso-Latorre, Baldomero, Rodriguez-Rodriguez, Javier, Aliseda, Alberto, Firtel, Richard A., and Lasheras, Juan C.

Subjects
Chemotaxis -- Evaluation, Cell adhesion -- Evaluation, Dictyostelium -- Chemical properties, Dictyostelium -- Physiological aspects, Cell migration -- Evaluation, Cells -- Motility, Cells -- Evaluation, Science and technology
Abstract

Cell motility plays an essential role in many biological systems, but precise quantitative knowledge of the biophysical processes involved in cell migration is limited. Better measurements are needed to ultimately build models with predictive capabilities. We present an improved force cytometry method and apply it to the analysis of the dynamics of the chemotactic migration of the amoeboid form of Dictyostelium discoideum. Our explicit calculation of the force field takes into account the finite thickness of the elastic substrate and improves the accuracy and resolution compared with previous methods. This approach enables us to quantitatively study the differences in the mechanics of the migration of wildtype (WT) and mutant cell lines. The time evolution of the strain energy exerted by the migrating ceils on their substrate is quasi-periodic and can be used as a simple indicator of the stages of the cell motility cycle. We have found that the mean velocity of migration v and the period of the strain energy T cycle are related through a hyperbolic law v = L/T, where L is a constant step length that remains unchanged in mutants with adhesion or contraction defects. Furthermore, when cells adhere to the substrate, they exert opposing pole forces that are orders of magnitude higher than required to overcome the resistance from their environment. Dictyostelium | myosin | traction forces | cytoskeleton | chemotaxis

Published
2007

11. Spatial and temporal regulation of 3-phosphoinositides by PI 3-kinase and PTEN mediates chemotaxis

Author

Hunamoto, Saturo, Meili, Ruedi, Parry, Lisa, Firtel, Richard A., and Lee, Susan

Subjects
Cytochemistry -- Research, Chemotaxis -- Physiological aspects, Phosphoinositides -- Physiological aspects, Dictyostelium -- Physiological aspects, Biological sciences
Abstract

Spatial/temporal regulation of 3-phosphoinositides by PI 3-kinase and PTEN has been found to mediate chemotaxis. The mechanisms of leading edge formation in chemotaxing Dictyostelium cells have been studied.

Published
2002

13. An SH2-domain-containing kinase negatively regulates the phosphatidylinositol-3 kinase pathway

Author

Moniakis, John, Funamoto, Satoru, Fukuzawa, Masashi, Meisenhelder, Jill, Araki, Tsuyoshi, Abe, Tomoaki, Meili, Ruedi, Hunter, Tony, Williams, Jeffrey, and Firtel, Richard A.

Subjects
Cytochemistry -- Research, Protein kinases -- Physiological aspects, Dictyostelium -- Genetic aspects, Chemotaxis -- Genetic aspects, Cellular signal transduction -- Research, Phosphatidylinositol -- Physiological aspects, Cytogenetics -- Research, Actin -- Physiological aspects, Plasma membranes -- Physiological aspects, Phagocytosis -- Physiological aspects, Biological sciences
Abstract

An SH2-domain-containing kinase has been found to regulate the phosphatidylinositol-3 kinase (PI3K) pathway negatively. It has been shown that SHK1 is necessary for proper phagocytosis and chemotaxis and it appears that SHK1 is necessary for the proper spatiotemporal control of F-actin levels in chemotaxing cells. SHK1 is localized at the plasma membrane/cortex.

Published
2001

15. Contributors

Author

Abrams, John M., primary, Adelman, John P., additional, Alcorn, Joseph L., additional, Alessi, Dario R., additional, Alexov, Emil, additional, Alford, Simon, additional, Alitalo, Kari, additional, Allison, James P., additional, Almo, Steven C., additional, Alory, Christelle, additional, Al-Shamkhani, Aymen, additional, Amundson, Sally A., additional, Anderson, Carl W., additional, Andersen, Jannik N., additional, Angel, Peter, additional, Appella, Ettore, additional, Arendshorst, William J., additional, Arkinstall, Steve, additional, Audhya, Anjon, additional, Avruch, Joseph, additional, Bader, Gary D., additional, Bagala, Cinzia, additional, Balch, William E., additional, Balsinde, Jesus, additional, Banerjee, Utpal, additional, Barford, David, additional, Bar-Sagi, Dafna, additional, Bartlett, Perry F., additional, Bastiaens, Philippe I.H., additional, Battelli, Chiara, additional, Baudhuin, Linnea M., additional, Beavil, Andrew J., additional, Beavil, Rebecca L., additional, Beavo, Joseph A., additional, Bello-Reuss, Elsa, additional, Bellum, Stephen, additional, Belmonte, Juan Carlos Izpisúa, additional, Bennett, Craig B., additional, Benovic, Jeffrey L., additional, Berridge, Michael J., additional, Beuning, Penny J., additional, Bhandari, Rashna, additional, Bhattacharya, Ananya, additional, Biel, Martin, additional, Bielinski, Vincent A., additional, Bilak, Hana, additional, Birnbaumer, Lutz, additional, Birrell, Geoff, additional, Bishop, Gail A., additional, Blackmer, Trillium, additional, Blackshear, Perry J., additional, Blattner, Christine, additional, Blaustein, Mordecai P., additional, Bokoch, Gary M., additional, Bonewald, Lynda F., additional, Bonomi, Marco, additional, Booden, Michelle A., additional, Boone, Charles, additional, Bootman, Martin D., additional, Bos, Johannes L., additional, Bradbury, Jane M., additional, Bradshaw, Ralph A., additional, Bresnick, Anne R., additional, Brevnova, Lena, additional, Brinkworth, Ross I., additional, Brown, Michael S., additional, Brown, Steven A., additional, Brunet, Anne, additional, Bucki, Robert, additional, Burgoyne, Robert D., additional, Buss, Janice E., additional, Butow, Ronald A., additional, Capdevila, Javier, additional, Carafoli, Ernesto, additional, Carlson, Cathrine R., additional, Carpenter, Graham, additional, Carrillo, Juan J., additional, Casey, Patrick J., additional, Catterall, William A., additional, Cerione, Richard A., additional, Cesareni, Gianni, additional, Chan, Andrew C., additional, Chang, Geoffrey, additional, Chao, Moses V., additional, Charbonneau, Harry, additional, Chen, Philip, additional, Cheng, Alan, additional, Chiu, Chris, additional, Chow, Dar-chone, additional, Chrisman, Ted D., additional, Christensen, Anne Elisabeth, additional, Chung, Jee Y., additional, Churchill, Grant C., additional, Ciechanover, Aaron, additional, Cingolani, Gino, additional, Claeysen, Sylvie, additional, Closset, Jean, additional, Cockcroft, Shamshad, additional, Cohen, Patricia T.W., additional, Cohen, Philip, additional, Colbran, Roger J., additional, Comstock, Clay E.S., additional, Conti, Marco, additional, Corbin, Jackie D., additional, Corda, Daniela, additional, Costagliola, Sabine, additional, Cote, Rick H., additional, Coughlin, Shaun R., additional, Cowart, L. Ashley, additional, Cox, Adrienne D., additional, Cragg, Mark S., additional, Crespo, José L., additional, Crosio, Claudia, additional, Daly, Christopher, additional, Damak, Sami, additional, Dasso, Mary, additional, David, Michael, additional, Davis, Anthony J., additional, Davis, Roger J., additional, Day, Richard N., additional, Degerman, Eva, additional, DeLano, Warren L., additional, Dell'Acqua, Mark L., additional, Délot, Emmanuèle, additional, Demple, Bruce, additional, Dennis, Edward A., additional, Denu, John M., additional, DePaoli-Roach, Anna A., additional, Der, Channing J., additional, de Rooij, Johan, additional, de Sauvage, Frederic, additional, Devreotes, Peter N., additional, Dewaste, Valérie, additional, Dickson, Robert B., additional, Diebold, Becky A., additional, Fiori, Pier Paolo Di, additional, Girolamo, Maria Di, additional, Diplexcito, Julie, additional, Dixon, Jack E., additional, Doms, Robert W., additional, Donoghue, Daniel J., additional, Doolittle, Russell F., additional, Døskeland, Stein Ove, additional, Dostmann, Wolfgang R.G., additional, Dreyer, Matthias K., additional, Du, Guo Guang, additional, Du, Keyong, additional, Duchen, Michael R., additional, Dunphy, William G., additional, Durgan, Joanne, additional, Dustin, Michael L., additional, Edwards, Peter A., additional, Egen, Jackson G., additional, Eiden, Lee E., additional, Elion, Elaine A., additional, Emr, Scott, additional, Engelhardt, Othmar G., additional, Erneux, Christophe, additional, Espenshade, Peter J., additional, Esplin, Edward D., additional, Evers, B. Mark, additional, Eyles, Joanne L., additional, Fame, Sheelagh, additional, Farquhar, Marilyn, additional, Feil, Robert, additional, Feng, Gui-Jie, additional, Fields, Stanley, additional, Fiordalisi, James J., additional, Firtel, Richard A., additional, Fitzgerald, Garret A., additional, Flint, Andrew, additional, Foiani, Marco, additional, Forman, Barry Marc, additional, Fornace, Albert J., additional, Francis, Sharron H., additional, Fritz, Günter, additional, Fruman, David A., additional, Galione, Antony, additional, Gandhi, Chris S., additional, Garbers, David L., additional, Garcia, K. Christopher, additional, Geiger, Benjamin, additional, Gerace, Larry, additional, Gerstner, Andrea, additional, Giaccia, Amato J., additional, Giannattasio, Michele, additional, Giguère, Vincent, additional, Glass, Christopher K., additional, Glennie, Martin J., additional, Glick, Jennifer L., additional, Goldstein, Joseph L., additional, Gopal, Venkatesh, additional, Gorospe, Myriam, additional, Govaerts, Cedric, additional, Graves, Paul R., additional, Gray, Patrick W., additional, Graziani, Irene, additional, Green, Douglas R., additional, Greenberg, Michael E., additional, Greenwald, Iva, additional, Gu, Haihua, additional, Gueven, Nuri, additional, Gutkind, J. Silvio, additional, Haeggström, Jesper Z., additional, Hall, Alan, additional, Hall, Michael N., additional, Haller, Otto, additional, Hamm, Heidi E., additional, Hannun, Yusef A., additional, Hansen, Carl A., additional, Harden, T. Kendall, additional, Hardie, D. Grahame, additional, Hasegawa, Kiminori, additional, Hawkins, Phillip T., additional, Haystead, Timothy A.J., additional, He, Xiao-lin, additional, Heizmann, Claus W., additional, Heldin, Carl-Henrik, additional, Hermiston, Michelle L., additional, Herrlich, Peter, additional, Hewat, Elizabeth A., additional, Hille, Bertil, additional, Hilton, Douglas J., additional, Hinchliffe, K.A., additional, Ho, Steffan N., additional, Ho, Su-Chin, additional, Hochstrasser, Mark, additional, Hofmann, Franz, additional, Hogue, Christopher W., additional, Hol, Wim G.J., additional, Holash, Jocelyn, additional, Holmgren, Robert A., additional, Honig, Barry, additional, Hostager, Bruce S., additional, Hubbard, Stevan R., additional, Huber, Michael, additional, Hunter, Tony, additional, Huttenlocher, Anna, additional, Hymowitz, Sarah G., additional, Ihle, James N., additional, Imler, Jean-Luc, additional, Irvine, R.F., additional, Isacoff, Ehud Y., additional, Iturrioz, Xavier, additional, Iversen, Lars F., additional, Iyengar, Ravi, additional, Jackson, Stephen P., additional, Jan, Lily Yeh, additional, Janiak-Spens, Fabiola, additional, Janmey, Paul A., additional, Jansen, Peter Gildsig, additional, Jarriault, Sophie, additional, Javitch, Jonathan A., additional, Jensen, Elwood V., additional, Jepsen, Kristen, additional, Jones, E. Yvonne, additional, Jones, Katherine A., additional, Jordan, J. Dedrick, additional, Joseph, Jomon, additional, Justement, Louis B., additional, Kafri, Yariv, additional, Kahn, Richard A., additional, Kang, Shin W., additional, Karlin, Arthur, additional, Kast-Woelbern, Heidi R., additional, Kaufman, Randal J., additional, Kazlauskas, Andrius, additional, Keen, James H., additional, Kemler, Rolf, additional, Kemp, Bruce E., additional, Kennedy, Mary B., additional, Kennedy, Matthew A., additional, Kikkawa, Ushio, additional, Kim, Albert H., additional, Kim, Soo-A, additional, Kim, Sung-Hou, additional, Kim, Youngjoo, additional, King-Jones, Kirst, additional, Kintner, Chris, additional, Kivimäe, Saul, additional, Klee, Claude B., additional, Klein, Rüdiger, additional, Kleppisch, Thomas, additional, Kliewer, Steven A., additional, Klinghoffer, Richard A., additional, Knoblich, Juergen A., additional, Kobe, Bostjan, additional, Kochs, George, additional, Kong-Beltran, Monica, additional, König, Rolf, additional, Koong, Albert C., additional, Korc, Murray, additional, Kornitzer, Daniel, additional, Kossiakoff, Anthony A., additional, Kotera, Jun, additional, Kovalenko, M.V., additional, Kozasa, Tohru, additional, Kozlov, Sergei, additional, Kozminski, Keith G., additional, Krugmann, Sonja, additional, Kuriyan, John, additional, Kurokawa, Riki, additional, Kwong, Peter D., additional, Lai, Wi S., additional, Lamar, Elise, additional, Lambert, Millard H., additional, Lambright, David G., additional, Lancet, Doron, additional, Landry, Reiko, additional, Langdon, Wallace Y., additional, Langeberg, Lorene K., additional, Lasko, Paul, additional, Latham, Vaughn, additional, Lavin, Martin F., additional, Lease, Kevin A., additional, Leffler, Hakon, additional, Lemmon, Mark A., additional, Leonard, Ann E., additional, Levitzki, Alexander, additional, Liao, Hong-Jun, additional, Liaw, Lucy, additional, Liberi, Giordano, additional, Lickert, Heiko, additional, Liddington, Robert C., additional, Lincoln, Thomas M., additional, Linder, Jürgen U., additional, Linder, Maurine E., additional, Liu, Hui, additional, Liu, Zhengchang, additional, Lohela, Marja K., additional, Louie, Sarah H., additional, Luttrell, Deirdre K., additional, Luttrell, Louis M., additional, Lyons, Karen M., additional, Macaulay, S. Lance, additional, Maceyka, Michael, additional, Maciag, Thomas, additional, Macian, Fernando, additional, MacKintosh, Carol, additional, MacLennan, David H., additional, Mahmood, Nadir A., additional, Malbon, Craig C., additional, Malik, Sohail, additional, Man, Orna, additional, Manahan, Carol L., additional, Mandinova, Anna, additional, Manganiello, Vincent C., additional, Manley, James L., additional, Mann, Matthias, additional, Manning, Gerald, additional, Manser, Ed, additional, Margeta-Mitrovic, Marta, additional, Margolskee, Robert F., additional, Marinissen, Julia, additional, Mariuzza, Roy A., additional, Marmor, Mina D., additional, Martin, G. Steven, additional, Martin, Karen H., additional, Martinez, Sergio E., additional, Mathews, Michael B., additional, Mayer, Bruce J., additional, Mayer, Mark L., additional, Mazzoni, Maria R., additional, McCormick, Frank, additional, McGowan, Clare H., additional, McKay, Melissa M., additional, McKeehan, Wallace L., additional, McLean, Alison J., additional, Means, Anthony R., additional, Meili, Ruedi, additional, Meng, Jingwei, additional, Merchant, Mark, additional, Mercurio, Frank, additional, Milligan, Graeme, additional, Ming, Guo-Li, additional, Minor, Daniel L., additional, Moghal, Nadeem, additional, Møller, Neils Peter H., additional, Mongillo, Marco, additional, Montminy, Marc, additional, Moon, Randall T., additional, Morimoto, Richard I., additional, Moss, Stephen E., additional, Mott, Helen R., additional, Mouta, Carla, additional, Muda, Marco, additional, Mumby, Marc C., additional, Murphy, Gretchen A., additional, Muzi-Falconi, Marco, additional, Nagaraj, Raghavendra, additional, Nahorski, Stefan R., additional, Nairn, Angus C., additional, Nash, Piers, additional, Neel, Benjamin G., additional, Newton, Alexandra C., additional, Nishizuka, Yasutomi, additional, Noel, Joseph P., additional, Nollen, Ellen A.A., additional, Nooren, Irene M.A., additional, O'Connor, Rodney, additional, Offermanns, Stefan, additional, Olender, Tsviya, additional, Ong, Shao-En, additional, Owen, Darerca, additional, Pagliari, Lisa J., additional, Pao, Lily, additional, Papaconstantinou, John, additional, Pardo, Leonardo, additional, Park, Hay-Oak, additional, Park, Young Chul, additional, Parker, Peter J., additional, Parsons, J. Thomas, additional, Passner, J.M., additional, Pawson, Tony, additional, Pelliccioli, Achille, additional, Perez-Polo, J. Regino, additional, Perrimon, Norbert, additional, Petite, Fabrice G., additional, Petroulakis, Emmanuel, additional, Pfaff, Samuel L., additional, Piehler, Jacob, additional, Pike, Linda J., additional, Pinkoski, Michael J., additional, Pixley, Fiona J., additional, Plevani, Paolo, additional, Poo, Mu-ming, additional, Pozzan, Tullioi, additional, Prescott, Stephen M., additional, Prudovsky, Igor, additional, Putney, James W., additional, Radimerski, Thomas, additional, Radzio-Andzelm, Elzbieta, additional, Ram, Prahlad T., additional, Rameh, Lucia, additional, Ramljak, Danica, additional, Ranscht, Barbara, additional, Rao, Anjana, additional, Raport, Carol J., additional, Reeves, Jacqueline D., additional, Rehman, Holger, additional, Reichman, Trevor W., additional, Reiter, Eric, additional, Resnick, Michael A., additional, Reth, Michael, additional, Rhee, Sue Goo, additional, Richter, Joel D., additional, Rietze, Rodney L., additional, Rini, James M., additional, Ripperger, Jürgen A., additional, Rizo, Josep, additional, Robishaw, Janet D., additional, Roderick, H. Llewelyn, additional, Roeder, Robert G., additional, Rohrschneider, Larry R., additional, Ron, David, additional, Rosenfeld, Michael G., additional, Rosenfeldt, Hans, additional, Rossman, Kent L., additional, Roth, Christopher B., additional, Rudolph, Markus G., additional, Ruppelt, Anja, additional, Saez, Lino, additional, Sakmar, Thomas P., additional, Salvesen, Guy S., additional, Sassone-Corsi, Paolo, additional, Saxe, Charles L., additional, Schäfer, Beat W., additional, Schibler, Ueli, additional, Schindler, Christian W., additional, Schmelzle, Tobias, additional, Schmid, Sandra L., additional, Schmidt, Anja, additional, Schmidt, Eric F., additional, Schreiber, Gideon, additional, Schultz, Joachim E., additional, Schwaller, Beat, additional, Schwamborn, Klaus, additional, Schwartz, Thue, additional, Schwindinger, William F., additional, Scita, Giorgio, additional, Scott, John D., additional, Scott, Shaun, additional, Seebeck, Thomas, additional, Serhan, Charles N., additional, Shabb, John B., additional, Shaw, Andrey S., additional, Shears, Stephen B., additional, Shenolikar, Shirish, additional, Shi, Lei, additional, Shin, Chanseok, additional, Shiozaki, Kazuhiro, additional, Shokat, Kevan M., additional, Shuttleworth, Trevor J., additional, Siderovski, David P., additional, Siegelbaum, Steven A., additional, Silverstein, Adam M., additional, Singer, Robert H., additional, Skinner, Michael K., additional, Slack-Davis, Jill K., additional, Smerdon, Stephen J., additional, Smith, Graeme C.M., additional, Smits, Guillaume, additional, Smolik, Sarah M., additional, Smotrys, Jessica E., additional, Smyth, Emer M., additional, Snyder, Jason T., additional, Sogame, Naoko, additional, Soldi, Raffaella, additional, Sondek, John, additional, Sonenberg, Nahum, additional, Sonneberg, Erica Dutil, additional, Sparrow, Lindsay G., additional, Spiegel, Sarah, additional, Sprang, Stephen R., additional, Srivastava, Deepak, additional, Stanfield, Robyn L., additional, Stanley, E. Richard, additional, Stauber, Deborah J., additional, Stefan, Christopher, additional, Stenson-Holst, Lena, additional, Stephens, Len, additional, Sternberg, Paul W., additional, Sternweis, Paul C., additional, Steward, Ruth, additional, Stickney, John T., additional, Stoker, Andrew W., additional, Strittmatter, Stephen M., additional, Stronach, Beth E., additional, Strong, Roland K., additional, Stroud, Robert M., additional, Südhof, Thomas C., additional, Sunahara, Roger K., additional, Sutton, Brian J., additional, Szabolcs, Sipeki, additional, Tang, Xiao-Bo, additional, Taskén, Kjetil, additional, Tatebe, Hisashi, additional, Tauszig-Delamasure, Servane, additional, Taylor, Colin W., additional, Taylor, Garry L., additional, Taylor, Laura J., additional, Taylor, Susan S., additional, Thomas, George, additional, Thomas, Robert P., additional, Thompson, E. Brad, additional, Thompson, Michael J., additional, Thornton, Janet M., additional, Thummel, Carl S., additional, Togashi, Hideaki, additional, Tong, Amy Hin Yan, additional, Tonks, Nicholas K., additional, Tontonoz, Peter, additional, Topham, M.K., additional, Torgersen, Knut Martin, additional, Tran, Hien, additional, Tremblay, Michel L., additional, Tsai, Ming-Jer, additional, Tsai, Sophia Y., additional, Tsunoda, Susan, additional, Turley, Stewart, additional, Tyson, Darren, additional, Van Etten, Robert L., additional, Vassart, Gilbert, additional, Verveer, Peter J., additional, Vlaeminck, Virginie, additional, de Vos, Abraham M., additional, Voss, Ty C., additional, Walczak, Robert, additional, Walker, Graham C., additional, Walker, John C., additional, Walter, Gernot, additional, Walter, Mark R., additional, Wang, Fen, additional, Wang, Jean Y.J., additional, Wang, Weiru, additional, Ward, Richard J., additional, Wedegaertner, Philip, additional, Wehrle, Christian, additional, Weiss, Arthur, additional, Weiss, Jamie L., additional, Wells, Alan, additional, Werner, Claudia, additional, West, Ann H., additional, Weston, Marie C., additional, Westwick, John K., additional, Wetterholm, Anders, additional, White, Morris F., additional, Whitman, Malcolm, additional, Whorton, Matt R., additional, Wiesmann, Christian, additional, Williams, Roger L., additional, Willis, William D., additional, Willson, Timothy M., additional, Wilson, Ian A., additional, Wiser, Ofer, additional, Wishart, Matthew J., additional, Wittinghofer, Alfred, additional, Woodgett, James R., additional, Worthylake, David K., additional, Wrana, Jeffrey L., additional, Wu, Hao, additional, Xiao, Yijin, additional, Xu, H. Eric, additional, Xu, Yan, additional, Xu, Zheng, additional, Yaffe, Michael B., additional, Yamada, Kenneth M., additional, Yang, Seun-Ah, additional, Yang, Wannian, additional, Yarden, Yosef, additional, Ye, Hong, additional, Ye, Weilan, additional, Yeates, Todd O., additional, Yin, Helen L., additional, York, John D., additional, Young, Edgar C., additional, Young, Kenneth W., additional, Young, Matthew A., additional, Young, Michael W., additional, Yu, Minmin, additional, Zaccai, Nathan R., additional, Zaccolo, Manuela, additional, Zamir, Eli, additional, von Zastrow, Mark, additional, Zhang, Chao, additional, Zhang, Xuewu, additional, Zhang, Zhong-Yin, additional, Zhou, Wenhong, additional, and Zoraghi, Roya, additional

Published
2003
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17. Study of calmodulin binding to the alternatively spliced C-terminal domain of the plasma membrane Ca2+ pump

Author

Kessler, Felix, Falchetto, Rocco, Heim, Roger, Meili, Ruedi, Vorherr, Thomas, Strehler, Emmanuel E., and Carafoli, Ernesto

Subjects
Calmodulin -- Research, Plasma membranes -- Research, Binding sites (Biochemistry) -- Research, Biological sciences, Chemistry
Abstract

The C-terminal portions of pump isoforms human plasma membrane Ca2+ (hPMCA) 1a-d obtained from alternatively spliced RNA were expressed in Escheirchia coli to study the variations in the functions of different regulatory domains encoded by isoforms hPMCA1 mRNAs. Purified 1a, 1c and 1d peptides were found to bind to calmodulin in a manner modulated by pH levels. This is attributed to the positive charges of histidine residues present in the alternatively spliced sequence.

Published
1992

19. Two poles and a compass

Author

Meili, Ruedi and Firtel, Richard A.

Subjects
Stereochemistry -- Research, Chemotaxis -- Genetic aspects, Guanosine triphosphatase -- Genetic aspects, Cell research -- Analysis, Biological sciences
Abstract

The authors review the publications on Rho GTPases which control neutrophil chemotaxis. The topics of interest include the role of activated Cdc42 in orientation of the cell's axis in a signaling complex, and the effect of Rho on formation of the uprod which reinforces polarization.

Published
2003

38. Rho Rocks PTEN

Author

Meili, Ruedi, primary, Sasaki, Atsuo T., additional, and Firtel, Richard A., additional

Published
2005
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48. Distribution of Traction Forces and Intracellular Markers Associated with Shape Changes During Amoeboid Cell Migration.

Author

LASHERAS, JUAN C., ALONSO-LATORRE, BALDOMERO, MEILI, RUEDI, BASTOUNIS, EFFIE, DEL ÁLAMO, JUAN C., and FIRTEL, RICHARD A.

Subjects
DISTRIBUTION (Probability theory), BIOMARKERS, AMOEBOID movement, CELL migration, FLUCTUATIONS (Physics), CELL cycle, PRINCIPAL components analysis, GREEN fluorescent protein, FLUORESCENCE microscopy
Abstract

During migration, amoeboid cells perform a cycle of quasi-periodic repetitive events (motility cycle). The cell length and the strain energy exchanged with the substrate oscillate in time with an average frequency, f, on top of which are imposed smaller random fluctuations. The fact that a considerable portion of the changes in cell shape are due to periodic repetitive events enables the use of conditional statistics methods to analyze the network of biochemical processes involved in cell motility. Taking advantage of this cyclic nature, we apply Principal Component analysis (PCA) and phase-average statistics to analyze the dominant modes of shape change and their association to the activity and localization of molecular motors. We analyze time-lapse measurements of cell shape, traction forces and fluorescence from green fluorescent protein (GFP) reporters for F-actin in Dictyostelium cells undergoing guided chemotactic migration. Using wild-type cells (wt) as reference, we investigated the contractile and actin crosslinking functions of myosin II by studying myosin II heavy chain null mutant cells (mhcA-) and myosin II essential light chain null cells (mlcE-). We found that the mechanical cycle of generation of traction stresses and cell shape changes remains remarkably similar for all cell lines, although these shape changes are implemented at a slower pace in myosin II null mutants, probably due to a reduced control on the spatial organization of the traction stresses. We found that wt, mlcE- and mhcA- cells utilize similar modes of shape changes during their motility cycle. The number of these dominant modes of shape changes is surprisingly few, with only three modes accounting for almost 70% of the variance in all cases. These principal shape modes are dilation/elongation, bending, and bulging of the front/back. The first mode is associated with forward pseudopod protrusion, while the second mode, resulting from sideways protrusion/ retraction, is associated to lateral asymmetries in both the cell traction forces and the distribution of F-actin, and is significantly less important in mhcA-cells. [ABSTRACT FROM AUTHOR]

Published
2011

49. Rac regulation of chemotaxis and morphogenesis in Dictyostelium.

Author

Kyung Chan Park, Rivero, Francisco, Meili, Ruedi, Lee, Susan, Apone, Fabio, and Firteils, Richard A.

Subjects
CHEMOTAXIS, DICTYOSTELIUM, ACTIN, CELL membranes, MORPHOGENESIS, POLYMERIZATION
Abstract

Chemotaxis requires localized F-actin polymerization at the site of the plasma membrane closest to the chemoattractant source, a process controlled by Rac/Cdc42 GTPases. We identify Dictyostelium RacB as an essential mediator of this process. RacB is activated upon chemoattractant stimulation, exhibiting biphasic kinetics paralleling F-actin polymerization. racB null cells have strong chemotaxis and morphogenesis defects and a severely reduced chemoattractant-mediated F-actin polymerization and PAKc activation. RacB activation is partly controlled by the PI3K pathway. pi3k½ null cells and wild-type cells treated with LY294002 exhibit a significantly reduced second peak of RacB activation, which is linked to pseudopod extension, whereas a PTEN hypomorph exhibits elevated RacB activation. We identify a RacGEF, RacGEF1, which has specificity for RacB in vitro. racgef1 null cells exhibit reduced RacB activation and cells expressing mutant RacGEF1 proteins display chemotaxis and morphogenesis defects. RacGEF1 localizes to sites of F-actin polymerization. Inhibition of this localization reduces RacB activation, suggesting a feedback loop from RacB via F-actin polymerization to RacGEF1. Our findings provide a critical linkage between chemoattractant stimulation, F-actin polymerization, and chemotaxis in Dictyostelium. [ABSTRACT FROM AUTHOR]

Published
2004
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