Nanoscale dynamics of actin filaments in the red blood cell membrane skeleton
Date
2022-02-18
Journal Title
Journal ISSN
Volume Title
Publisher
Molecular Biology of the Cell
Abstract
Red blood cell (RBC) shape and deformability are supported by a planar network of short actin filament (F-actin) nodes (∼37 nm length, 15–18 subunits) interconnected by long spectrin strands at the inner surface of the plasma membrane. Spectrin-F-actin network structure underlies quantitative modeling of forces controlling RBC shape, membrane curvature, and deformation, yet the nanoscale organization and dynamics of the F-actin nodes in situ are not well understood. We examined F-actin distribution and dynamics in RBCs using fluorescent-phalloidin labeling of F-actin imaged by multiple microscopy modalities. Total internal reflection fluorescence and Zeiss Airyscan confocal microscopy demonstrate that F-actin is concentrated in multiple brightly stained F-actin foci ∼200–300 nm apart interspersed with dimmer F-actin staining regions. Single molecule stochastic optical reconstruction microscopy imaging of Alexa 647-phalloidin-labeled F-actin and computational analysis also indicates an irregular, nonrandom distribution of F-actin nodes. Treatment of RBCs with latrunculin A and cytochalasin D indicates that F-actin foci distribution depends on actin polymerization, while live cell imaging reveals dynamic local motions of F-actin foci, with lateral movements, appearance and disappearance. Regulation of F-actin node distribution and dynamics via actin assembly/disassembly pathways and/or via local extension and retraction of spectrin strands may provide a new mechanism to control spectrin-F-actin network connectivity, RBC shape, and membrane deformability.
Description
This article was originally published in Molecular Biology of the Cell. The version of record is available at: https://doi.org/10.1091/mbc.E21-03-0107. This article will be embargoed until 04/18/2022.
Keywords
erythrocyte, membrane skeleton, membrane deformation, membrane microdomains, TIRF, super-resolution microscopy, STORM
Citation
Nowak, Roberta B., Haleh Alimohamadi, Kersi Pestonjamasp, Padmini Rangamani, and Velia M. Fowler. “Nanoscale Dynamics of Actin Filaments in the Red Blood Cell Membrane Skeleton.” Molecular Biology of the Cell 33, no. 3 (2022): ar28. https://doi.org/10.1091/mbc.E21-03-0107.