Activity-driven fluctuations in living cells

¹ Laboratoire Matière et Systèmes Complexes, UMR 7057 CNRS/P7, Université Paris Diderot 10 rue Alice Domon et Léonie Duquet, 75205 Paris cedex 13, France
² School of Engineering and Applied Sciences, Harvard University - Cambridge, MA 02138, USA
³ Department of Chemical Physics, Weizmann Institute of Science - 76100 Rehovot, Israel

^(b) paolo.visco@univ-paris-diderot.fr (correspondig author)

Received: 7 April 2015
Accepted: 22 May 2015

Abstract

We propose a model for the dynamics of a probe embedded in a living cell, where both thermal fluctuations and nonequilibrium activity coexist. The model is based on a confining harmonic potential describing the elastic cytoskeletal matrix, which undergoes random active hops as a result of the nonequilibrium rearrangements within the cell. We describe the probe's statistics and we bring forth quantities affected by the nonequilibrium activity. We find an excellent agreement between the predictions of our model and experimental results for tracers inside living cells. Finally, we exploit our model to arrive at quantitative predictions for the parameters characterizing nonequilibrium activity, such as the typical time scale of the activity and the amplitude of the active fluctuations.