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bioRxiv · 10.1101/2020.05.27.119453

Neuronal activity remodels the F-actin based submembrane lattice in dendrites but not axons of hippocampal neurons

Lavoie-Cardinal, F.·Bilodeau, A.·Lemieux, M.·Gardner, M.-A.·Wiesner, T.·Laramee, G.·Gagne, C.·De Koninck, P.
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Abstract

The nanoscale organization of the F-actin cytoskeleton in neurons comprises membrane-associated periodical rings, bundles, and longitudinal fibers. The F-actin rings have been observed predominantly in axons but only sporadically in dendrites, where fluorescence nanoscopy reveals various patterns of F-actin arranged in mixed patches. These complex dendritic F-actin patterns pose a challenge for investigating quantitatively their regulatory mechanisms. We developed here a weakly supervised deep learning segmentation approach of fluorescence nanoscopy images of F-actin in cultured hippocampal neurons. This approach enabled the quantitative assessment of F-actin remodeling, revealing the disappearance of the rings during neuronal activity in dendrites, but not in axons. The dendritic F-actin cytoskeleton of activated neurons remodeled into longitudinal fibers. We show that this activity-dependent remodeling involves Ca2+ and NMDA-dependent mechanisms. This highly dynamic restructuring of dendritic F-actin based submembrane lattice into longitudinal fibers may serve to support activity-dependent membrane remodeling, protein trafficking and neuronal plasticity.

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Lavoie-Cardinal, F., Bilodeau, A., Lemieux, M., Gardner, M.-A., Wiesner, T., Laramee, G., Gagne, C., De Koninck, P.. 2020-06-01. Neuronal activity remodels the F-actin based submembrane lattice in dendrites but not axons of hippocampal neurons. https://doi.org/10.1101/2020.05.27.119453

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