Characterizing the nanoscale organization of the actin/spectrin membrane-associated periodic skeleton in rodent nerves using 3D-STORM microscopy

NAHIR G. GAZAL; ALAN M. SZALAI; LUCÍA F. LOPEZ; E. AXEL GOROSTIZA; FERNANDO D. STEFANI; N. UNSAIN

Congreso; XXXVI Congreso Reunión Anual ? Sociedad Argentina de Investigación en Neurociencia. Modalidad Virtual; 2021

It has been recently discovered that axons and dendrites possess a particular arrangement of their corticalskeleton, referred to as the Membrane-associated actin/spectrin Periodic Skeleton (MPS). The MPS is aperiodic protein structure consisting of actin "rings" located transversely to the axon and separated every 190nm by α/β-spectrin tetramers "spacers". The MPS can only be described using super-resolution (SR) microscopyapproaches, since its spatial features lay below the diffraction limit of light. Most of published studies describethe MPS in vitro (in cultured neurons) and the precise organization of the spectrin ?spacers? within each periodis poorly resolved. We have thus begun a project to shed light into this in rodent nerve sections, that is, in situ,using 3D-STORM SR microscopy. We have first established a protocol for the examination of mouse optic andsciatic nerves preparations suitable for them by 3D-STORM. We have preliminary evidence for a model inwhich spectrin tetramers are arranged in each period at regular and fixed distances irrespective of axonalidentity and that scales with axon diameter. We have also evidenced that the localization of a spectrin tetramerin one period is correlated with the position of tetramers in neighboring periods, suggesting a structuralconstrain for their interaction with actin rings. We believe that describing the MPS at the nanometer scale insitu will provide meaningful insights into its possible functions.