In situ organization of the actin/spectrin membrane-associated periodic skeleton of axons with nanometer resolution

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

Recently, actin, spectrin and associated proteins have been discovered to form a membrane-associated periodic skeleton(MPS) that is ubiquitously present in mature axons of all neuronal types evaluated up to the moment. MPS is a periodicprotein structure consisting of actin "rings" located transversely to the axon and separated every 190 nm by α / β-spectrin"spacers" extended along the axon. Since its discovery, the characterization of MPS has been performed almost exclusivelyin cultured neurons; namely artificial environments in two dimensions. Hence, we proposed to study the spatialorganization and biology of these structures in their ?natural? environment, that is, in situ. Moreover, it is still not clear howspectrin tetramers are organized in each segment of this periodic scaffold. Taking all this into account, we have begun toanalyze the transversal organization of spectrin tetramers in the MPS of axons within mouse nerves, namely optic andsciatic nerves. The MPS cannot be evidenced by conventional fluorescence microscopy, since its periodicity (~190 nm) isbelow the resolution limit (~250nm). To reach the needed resolution in tissue, we are combining 3D-STOchasticReconstruction Microscopy (STORM) and tissue Expansion Microscopy (ExM) to gain both resolution and transparency. Iam going to present data that allow us to identify common and distinct organization rules of the spectrin tetramers withinthe MPS in nerve tissue.