Fig. 3: Non-muscle myosin II (NMII) filaments bind to the MPS and play a role in radial contractility of axons.
From: Proteomic and functional analyses of the periodic membrane skeleton in neurons
a Antibody-binding epitopes at the C- or N-terminus of a NMII bipolar filament (left), and the antibody-binding epitope at the C-terminus of βII-spectrin located near the center of the spectrin tetramer. b Left: Two-color STORM image of βII-spectrin (C-terminus, green) and NMIIB (N-terminus, magenta) in axons of cultured hippocampal neurons. Right: Average 1D distributions of βII-spectrin (C-terminus, green) and NMIIB (N-terminus, magenta) signals projected to the longitudinal axon axis from many axon segments. Scale bar: 1 μm. c Similar to (b) but for the C-terminus of NMIIB. d Average 1D cross-correlation between the distributions of βII-spectrin (C-terminus) and NMIIB (N-terminus) (magenta) and between the distributions of βII-spectrin (C-terminus) and NMIIB (C-terminus) (green) along the axons of cultured neurons, derived from 20–50 axon segments. The average 1D auto-correlation of βII-spectrin distribution (black) is shown as a reference. e Average 1D autocorrelation amplitudes of βII-spectrin distribution (left) and average periodic spacing of the MPS (right), for axons of untreated neurons, Blebbistatin (Bleb)-treated neurons, and neurons transfected with adenoviruses expressing shRNAs against NMIIA, NMIIB, or both NMIIA and NMIIB heavy chains. f Average diameter of axons (measured by βII spectrin immunostainining) for untreated neurons, Bleb-treated neurons, and neurons treated with shRNAs against NMIIA, NMIIB, or both NMIIA and NMIIB heavy chains. *p < 0.05 (two-sided unpaired student’s t-test); p-values (from left to right): 4.7 × 10−2 and 4.7 × 10−2. g Average diameter of axons (measured by CTB staining) for neurons treated with control (scramble) shRNA, neurons treated with control shRNA and Bleb, neurons treated with βII-spectrin shRNA, and neurons treated with βII-spectrin shRNA and Bleb. *p < 0.05 (two-sided unpaired student’s t-test); p-values (from left to right): 3.2 × 10−2, 1.0 × 10−2 and 3.3 × 10−2. Data are mean ± s.e.m (n = 3 biological replicates; 50–130 axonal regions per condition). STORM images in b–c are representative examples from three independent experiments with similar results. Source data are provided in the Source Data file.
