Cofilin is one of the best-known actin-binding proteins and has a multitude of roles in diverse cellular processes. Under conditions of stress, cofilin–actin rods form in either the nucleus or cytoplasm as a potential means to stop actin tread-milling and make free ATP available. These cofilin–actin rods have been implicated in neurodegeneration, such as in Huntington's disease (HD) and Alzheimer's disease (AD), suggesting that the dynamics of the actin cytoskeleton is crucial for maintaining neuronal health. On page , Ray Truant and colleagues further characterise the dynamics of the actin–cofilin interaction by analysing the nuclear import and export of cofilin in detail. They identify a previously uncharacterised nuclear export signal (NES) in cofilin, and also show that its known nuclear localisation signal (NLS) is of a bipartite type. Using advanced imaging microscopy approaches and automated image analysis in live cells, the authors show that subtle mutations in the NLS still allow cofilin to bind to actin in vivo, yet affect cofilin dynamics during stress. On the basis of their results, they propose that the nuclear shuttling of cofilin is dynamically regulated during stress and is crucial for cofilin–actin rod formation in response to stress, suggesting that targeting cofilin nuclear shuttling might be a feasible therapeutic approach for HD and AD.
