Active forces in living cells: molecular motors and transport

M. C. DE ROSSI; LUCIANA BRUNO; VALERIA LEVI; DIANA E. WETZLER

Buenos Aires

Congreso; 2nd Protein Biophysics at the End of the World.; 2017

Active forces generated by molecular motors are responsible for numerous functions within living cells, including cytoskeletal organization as well as organelle transport. By tracking individual fluorescently labelled microtubules (MTs) we can study their shape evolution and associate certain events to active forces. We focus on sudden, localized bending events called bucklings, since they are directly related to active forces. MT bucklings are characterized by sizes of a few microns and occur naturally in living cells. We explore the temporal evolution of these events and observe that they can be described by the same mechanical approach despite their size and duration may vary amongst events. In order to obtain an in-depth understanding of these episodes we performed numerical simulations of filaments in a cytoplasmatic-like environment using a worm like chain model. Under different load scenarios we are able to associate force application on the MTs with buckling amplitude progressions. Using a two color fluorescence microscopy technique we study the interplay between transported vesicles (fm4-64 labelled endosomes) and individual MTs, in particular we focus on cases where the transported load seemingly caused a buckling event. With these experimental examples we drew a final feedback with the numerical simulations and observed the buckling evolutions in cases when the force acts parallel o perpendicular to the filament