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Mapping correlated membrane pulsations and fluctuations in human cells

Pelling, A.E.; Veraitch, F.S.; Chu, C.; Nicholls, B.M.; Hemsley, A.L.; Mason, C.; Horton, M.A.; (2007) Mapping correlated membrane pulsations and fluctuations in human cells. Journal of Molecular Recognition , 20 (6) pp. 467-475. 10.1002/jmr.832.

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Abstract

The cell membrane and cytoskeleton are dynamic structures that are strongly influenced by the thermo-mechanical background in addition to biologically driven mechanical processes. We used atomic force microscopy (AFM) to measure the local membrane motion of human foreskin fibroblasts (HFFs) which were found to be governed by random and non-random correlated mechanical processes. Interphase cells displayed distinct membrane pulsations in which the membrane was observed to slowly contract upwards followed by a recovery to its initial position. These pulsations occurred one to three times per minute with variable amplitudes (20-100 pN) separated by periods of random baseline fluctuations with amplitudes of <20 pN. Cells were exposed to actin and microtubule (MT) destabilizing drugs and induced into early apoptosis. Mechanical pulsations (20-80 pN) were not prevented by actin or MT depolymerization but were prevented in early apoptotic cells which only displayed small amplitude baseline fluctuations (<20 pN). Correlation analysis revealed that the cell membrane motion is largely random; however several non-random processes, with time constants varying between 2 and 35 s are present. Results were compared to measured cardiomyocyte motion which was well defined and highly correlated. Employing automated positioning of the AFM tip, interphase HFF correlation time constants were also mapped over a 10 µm2 area above the nucleus providing some insights into the spatial variability of membrane correlations. Here, we are able to show that membrane pulsations and fluctuations can be linked to physiological state and cytoskeletal dynamics through distinct sets of correlation time constants in human cells.

Type:Article
Title:Mapping correlated membrane pulsations and fluctuations in human cells
DOI:10.1002/jmr.832
Publisher version:http://dx.doi.org/10.1002/jmr.832
Language:English
Keywords:Atomic force microscopy, fluorescence microscopy, autocorrelation analysis, cell membrane fluctuations, apoptosis, cytoskeleton, spatial autocorrelation plots
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > CoMPLEX - Maths and Physics in the Life Sciences and Experimental Biology
UCL > School of BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
UCL > School of BEAMS > Faculty of Engineering Science > Biochemical Engineering

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