The spectrin-based membrane skeleton is asymmetric and remodels during neural development in C. elegans

Perturbation of spectrin-based membrane mechanics causes hereditary elliptocytosis and spinocerebellar ataxia, but the underlying cellular basis of pathogenesis remains unclear. Here, we introduced conserved disease-associated spectrin mutations into the Caenorhabditis elegans genome and studied the contribution of spectrin to neuronal migration and dendrite formation in developing larvae. The loss of spectrin resulted in ectopic actin polymerization outside of the existing front and secondary membrane protrusions, leading to defective neuronal positioning and dendrite morphology in adult animals. Spectrin accumulated in the lateral region and rear of migrating neuroblasts and redistributes from the soma into the newly formed dendrites, indicating that the spectrin-based membrane skeleton is asymmetric and remodels to regulate actin assembly and cell shape during development. We affinity-purified spectrin from C. elegans and showed that its binding partner ankyrin functions with spectrin. Asymmetry and remodeling of the membrane skeleton might enable spatiotemporal modulation of membrane mechanics for distinct developmental events.