The mechanical properties of vertebrate cells are largely defined by the system of intermediate filaments (IF). As part of a dense network, IF polymers are constantly rearranged and relocalized in the cell to fulfill their duty as cells change shape, migrate, or divide. With the development of new imaging technologies, such as photoconvertible proteins and super-resolution microscopy, a new appreciation for the complexity of IF dynamics has emerged. This review highlights new findings about the transport of IF, the remodeling of filaments by a process of severing and re-annealing, and the subunit exchange that occurs between filament precursors and a soluble pool of IF. We will also discuss the unique dynamic features of the keratin IF network. Finally, we will speculate about how the dynamic properties of IF are related to their functions.
The dynamics of intermediate filaments include microtubule-dependent transport, end-to-end fusion, severing, and subunit exchange. These processes can now be observed in real time using improved imaging technologies and photoconvertible probes. Dynamics may balance the forms of intermediate filaments (soluble, ULF, or filamentous) that could play differential roles in the cell.