Neuronal Membrane-Associated Periodic Skeleton Imaging Using Stochastic Optical Reconstruction Microscopy

Abstract

Using Stochastic optical reconstruction microscopy (STORM), researchers have found that actin, spectrin, and adducin form a membrane-associated periodic skeleton (MPS) in the axons of mammalian neurons. In the neuronal MPS, short actin filaments, capped by adducin, form ring-like structures that wrap around the circumference of neurites, and these rings are periodically spaced along the neurites by spectrin tetramers, forming a quasi-1D lattice structure. In this dissertation, I present the studies about the organization and development of the MPS in the soma and dendrites, as well as the comprehensive interactome of the neuronal MPS, providing more insights into the functions of neuronal MPS. To study the organization and development of MPS in the somatodendritic compartment and how it is different from that of the axonal compartment, we investigated the spatial organizations of spectrin, actin, and adducin in the soma and dendrites of cultured hippocampal neurons at different developmental stages, and compared results with those obtained in axons, using super-resolution imaging. The detailed quantifications reveal that 1D MPS forms with a lower propensity in dendrites than in axons at any developmental stage examined. We found that the dendritic MPS develops more slowly than axonal MPS. In addition, for a fraction of imaged somatodendritic regions, we observed a 2D polygonal lattice structure beneath the plasma membrane, resembling the expanded erythrocyte membrane skeleton structure. These results suggest MPS is differentially regulated across different subcompartments of neurons. Next, using super-resolution imaging, we found more than 20 new MPS-interacting proteins that show 1D periodic distribution along the axons of cultured hippocampal neurons. We then determined the essential components for MPS formation and maintenance in axons. At last, we demonstrate that MPS is an essential functional molecular architecture for several biological processes.