Exploring cytoskeletal diversity in neurons

Often in biology, form follows function. For example, the ability of neurons to receive, process, and transmit information depends on their polarized organization into axons and dendrites. The cytoskeleton and associated motor proteins shape cells and establish spatial organization. Microtubules (MTs) and actin are core components of the cytoskeleton and are assembled through head-to-tail polymerization of α- and β-tubulin heterodimers and actin monomers, respectively, resulting in asymmetric, polarized polymers with two different ends, called plus and minus ends. The spatially regulated polymerization of MTs and actin can drive morphological transitions, such as local protrusion of the plasma membrane, to drive cell migration or the development of specialized extensions, such as axons or dendrites and their branches. In addition, the structural asymmetry of MTs and actin enables cytoskeletal motor proteins (myosin, kinesin, and dynein) to walk toward a specific end of the fibers. Given the extreme dimensions and functional compartmentalization of neurons, such active transport is critical to sort and distribute cellular cargoes. Recent studies have used advanced microscopy to reveal how the cytoskeleton takes many different forms to facilitate local functions in neurons (see the figure).