Probing cytoskeletal modulation of passive and active intracellular dynamics using nanobody-functionalized quantum dots.
The cytoplasm is a highly complex and heterogeneous medium that is structured by the cytoskeleton. How local transport depends on the heterogeneous organization and dynamics of F-actin and microtubules is poorly understood. Here we use a novel delivery and functionalization strategy to utilize quantum dots (QDs) as probes for active and passive intracellular transport. Rapid imaging of non-functionalized QDs reveals two populations with a 100-fold difference in diffusion constant, with the faster fraction increasing upon actin depolymerization. When nanobody-functionalized QDs are targeted to different kinesin motor proteins, their trajectories do not display strong actin-induced transverse displacements, as suggested previously. Only kinesin-1 displays subtle directional fluctuations, because the subset of microtubules used by this motor undergoes prominent undulations. Using actin-targeting agents reveals that F-actin suppresses most microtubule shape remodelling, rather than promoting it. These results demonstrate how the spatial heterogeneity of the cytoskeleton imposes large variations in non-equilibrium intracellular dynamics.
Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Eugene A
EA
Katrukha
Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.|RG Neuroplasticity, Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany.
Marina
M
Mikhaylova
Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Hugo X
HX
van Brakel
Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Paul M
PM
van Bergen En Henegouwen
Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Anna
0000-0002-9048-8614
A
Akhmanova
Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Casper C
CC
Hoogenraad
Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Lukas C
LC
Kapitein
D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D001693:Biological Transport, Active; D019556:COS Cells; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D045663:Quantum Dots
D000199:Actins; D009218:Myosins; D016547:Kinesins