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31
Abstracts
VOLUME CHANGES TRIGGERED BY ANISOSMOTIC MEDIA IN INTACT AND PERMEABILIZED A549 CELLS: ROLE OF CYTOSKELETON NETWORK
Platonova, A.A.1' 2, Orlov, S.N.1' 2, and Grygorczyk, R.1
1 Research Centre, University of Montreal Hospital, Montreal, Canada
2 Department of Biophysics and Laboratory of Physical Chemistry of Biological Membranes, M.V. Lomonosov Moscow State University, Moscow, Russian Federation
Differing strikingly from aqueous solution, the gellike cytoplasm of all cells shows enhanced viscosity, slowed diffusion and an ability to retain water. However, the gel-like character of the cytoplasm has not been fully documented for mammalian cells, and its impact on cellular processes, such as volume sensing and regulation, remains unclear. Previously, we employed 3D imaging light microscopy developed in our laboratory [1] and revealed that gentle perforation of the surface membrane with digitonin preserves the gel-like character of the whole-cell cytoplasm. Moreover, we demonstrated that the cytoplasm of substrate-attached permeabilized cells swells or shrinks in response to alterations of external osmolality [2]. Numerous studies demonstrated important role of cytoskele-ton in cell volume adjustment. In this study, we compared cell volume adjustment of intact and permeabilized A549 cells subjected to disruption of microtubules by vin-blastine (VB) and microfilament disassembly by cyto-chalasin B (CB). Both CB and VB decreased the maximal amplitude of cell swelling in hyposmotic medium and completely abolished cell volume increment triggered by hyposmotic medium in permeabilized cells. Consis-
tently with previous reports, cell swelling of A549 cells in hyposmotic medium was accompanied by rapid regulatory volume decrease (RVD) that was absent in permeabilized cells. Neither CB nor VB abolished RVD seen in intact cells. In contrast to swelling, 30-min shrinkage of A549 cells resulted in negligible regulatory volume increase. Permeabilization did not significantly affect the amplitude of shrinkage evoked by hyperosmotic medium. Both in intact and permeabilized cells, the rates of shrinkage were sharply attenuated by CB. Viewed collectively, our results demonstrate that cytoskeleton network has a minor impact on intracellular signalling involved in RVD but plays a key role in the behaviour of cytoplasmic biogel as an os-mosensor.
References
1. Boudreault, F. and Grygorczyk, R. Evaluation of rapid volume changes of substrate-adherent cells by conventional microscopy 3D imaging. J. Microscopy, 2004, 215, pp. 302312.
2. Fels, J., Orlov, S.N., and Grygorczyk, R. The hydrogel nature of mammalian cytoplasm contributes to osmosensing and extracellular pH sensing. Biophys. J., 2009, 96, pp. 4276-4285.
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Бюллетень сибирской медицины, 2013, том 12, № 4, с. 24-68
