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Rho GTPases link cellular contractile force to the density and distribution of nanoscale adhesions
KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
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2012 (English)In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 26, no 6, 2374-2382 p.Article in journal (Refereed) Published
Abstract [en]

The ability of cells to adhere and to exert contractile forces governs their capacity to move within an organism. The cytoskeletal regulators of the Rho GTPase proteins are involved in control of the contractile forces of cells. To elucidate the basis of cell migration, we analyzed contractile forces and nanoscale adhesion-related particles in single cells expressing constitutively active variants of Rho GTPases by using traction-force microscopy and ultra-high-resolution stimulated emission depletion microscopy, respectively. RhoAV14 induced large increases in the contractile forces of single cells, with Rac1L61 and RhoDV26 having more moderate effects. The RhoAV14- and RhoDV26-induced forces showed similar spatial distributions and were accompanied by reduced or unaltered cell spreading. In contrast, the Rac1L61-induced force had different, scattered, force distributions that were linked to increased cell spreading. All three of these Rho GTPase activities caused a loss of thick stress fibers and focal adhesions and a more homogenous distribution of nanoscale adhesion-related particles over the ventral surface of the cells. Interestingly, only RhoAV14 increased the density of these particles. Our data suggest a Rac1-specific mode for cells to generate contractile forces. Importantly, increased density and a more homogenous distribution of these small adhesion-related particles promote cellular contractile forces.-Gad, A. K. B., Ronnlund, D., Spaar, A., Savchenko, A. A., Petranyi, G., Blom, H., Szekely, L., Widengren, J., Aspenstrom, P. Rho GTPases link cellular contractile force to the density and distribution of nanoscale adhesions.

Place, publisher, year, edition, pages
2012. Vol. 26, no 6, 2374-2382 p.
Keyword [en]
traction force microscopy, STED microscopy
National Category
Biochemistry and Molecular Biology
URN: urn:nbn:se:kth:diva-98726DOI: 10.1096/fj.11-195800ISI: 000305017200015ScopusID: 2-s2.0-84861789262OAI: diva2:539094
Swedish Research CouncilScience for Life Laboratory - a national resource center for high-throughput molecular bioscience

QC 20120703

Available from: 2012-07-03 Created: 2012-07-02 Last updated: 2014-02-07Bibliographically approved
In thesis
1. Super resolution optical imaging – image analysis, multicolor development and biological applications
Open this publication in new window or tab >>Super resolution optical imaging – image analysis, multicolor development and biological applications
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on super resolution STED optical imaging. STED provides a wealth of new informational content to the acquired images by using stimulated emission to surpass the diffraction limit in optical fluorescence microscopy. To further increase the informational content, a new method to perform multicolor STED imaging by exploiting differences in the photostability and excitation spectra of dyes is presented. In order to extract information from the images, computational algorithms which handle the new type of high resolution informational content are developed.

We propose that multicolor super resolution imaging in combination with image analysis can reduce the amount of clinical samples required to perform accurate cancer diagnosis. To date, such diagnosis is based mainly on significant amounts of tissue samples extracted from the suspected tumor site. The sample extraction often requires anesthetics and can lead to complications such as hematoma, infections and even cancer cell ceding along the needle track. We show that by applying multicolor STED and image analysis, the information gained from single cells is greatly increased. We therefore propose that accurate diagnosis can be based on significantly less extracted tissue material, allowing for a more patient friendly sampling. This approach can also be applied when studying blood platelets, where we show how the high informational content can be used to identify platelet specific activational states. Since platelets are involved in many different types of diseases, such analysis could provide means of performing truly minimally invasive diagnostics based on a simple blood test.

In addition, our data makes it possible to understand in finer detail the underlying mechanisms rendering cells metastasis competent. We combine the high resolution spatial information provided by STED with information regarding the adhesive forces of cells measured by TFM (Traction Force Microscopy) and the cell stiffness measured by AFM (Atomic Force Microscopy). Such comparisons provide a link between the specific highly resolved protein distributions and different cellular mechanics and functions.

This thesis also includes STED imaging and analysis on the spatial organization of neuronal synaptic regulating proteins, implicating the speed with which neuronal signaling can be regulated.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. x, 86 p.
TRITA-FYS, ISSN 0280-316X ; 2014:04
Stimulated emission depletion (STED) microscopy, nanoscopy, multicolor, image analysis, diagnostics, cancer, metastasis
National Category
Physical Sciences
Research subject
Biological Physics
urn:nbn:se:kth:diva-141011 (URN)978-91-7595-001-3 (ISBN)
Public defence
2014-02-28, FB42, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:51 (English)

QC 20140207

Available from: 2014-02-07 Created: 2014-02-05 Last updated: 2014-02-07Bibliographically approved

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