Unraveling the ultrastructure and functions of the neuronal membrane skeleton using super-resolution fluorescence microscopy

Title : Unraveling the ultrastructure and functions of the neuronal membrane skeleton using super-resolution fluorescence microscopy

Abstract:

The neuronal membrane-associated periodic skeleton (MPS), composed of actin, spectrin, and associated molecules, forms a lattice-like cortical structure whose molecular composition and functions have remained incompletely understood. Using co-immunoprecipitation and mass spectrometry, we identified hundreds of candidate MPS-interacting proteins spanning diverse functional categories. Super-resolution imaging of representative proteins, including previously unknown structural components, motor proteins, cell adhesion molecules (CAMs), ion channels, and signaling proteins, revealed periodic distributions characteristic of the MPS along neurites. Genetic perturbations of the MPS and its interacting proteins indicate roles in axon-axon and axon-dendrite interactions, axon diameter regulation. Functionally, the MPS serves as a dynamic platform for signal integration. It recruits G protein-coupled receptors (GPCRs), CAMs, and receptor tyrosine kinases (RTKs) in response to extracellular cues, promoting colocalization and RTK transactivation that trigger extracellular signal-regulated kinase (ERK) signaling. In addition to signaling, the MPS spatially gates major forms of endocytosis by restricting pit formation to MPS-free “clearing” zones across axonal and somatodendritic compartments. Disruption of the MPS enhances both basal and ligand-induced endocytosis, while ligand-triggered endocytosis activates ERK signaling to further remodel the MPS, establishing a self-reinforcing feedback circuit. Notably, MPS integrity limits amyloid precursor protein (APP) endocytosis and suppresses amyloid-β 1-42 production, linking cytoskeletal organization to neuronal health and disease susceptibility. Together, these findings reveal the MPS as a dynamic, multifunctional scaffold that coordinates structural integrity, protein interactions, receptor signaling, and membrane trafficking, establishing a unifying principle by which cytoskeletal architecture shapes neuronal function, connectivity, and homeostasis.

Biography:

Dr. Ruobo Zhou earned his B.S. in Applied Physics from University of Science and Technology of China (USTC). He then pursued graduate studies with Prof. Taekjip Ha at the University of Illinois at Urbana–Champaign (UIUC), where he developed a hybrid single-molecule instrument combining optical tweezers with single-molecule fluorescence microscopy and applied this technique to illuminate critical protein-DNA interactions in vitro (cell-free systems) involved in DNA repair, replication, and recombination. Dr. Zhou then completed his postdoctoral training in the laboratory of Prof. Xiaowei Zhuang in the Department of Chemistry and Chemical Biology at Harvard University, where he extended his analyses of functional biomolecular interactions from cell-free to in vivo systems, applying mass-spectrometry-based analysis and super-resolution fluorescence microscopy to study protein organizations and  protein-protein interactions at the plasma membrane of neurons. In 2021, Dr. Zhou joined the Department of Chemistry at the Pennsylvania State University as an Assistant Professor. His research aims to quantitatively and functionally dissect the compartmentalization and spatiotemporal organization of protein-protein and protein-RNA interactions involved in fundamental cell functions as well as in cancer and neurodegenerative diseases, from single-molecule to single-cell levels, using cutting-edge single-molecule techniques and super-resolution fluorescence microscopy, mathematical modeling, highly interdisciplinary cell and molecular biology tools, and high throughput “omics” approaches such as mass spectrometry-based proteomic analysis and transcriptome-scale RNA imaging. Dr. Zhou has been recognized with several awards, including being named an HHMI fellow of Life Sciences Research Foundation, a Scialog Fellow for Advancing Bioimaging, and a recipient of the NIGMS Maximizing Investigators' Research Award (MIRA).