Journal: bioRxiv

Article Title: Spatially Distinct Myosin II Architectures Regulate Protrusion Dynamics and Directional Persistence during Immune Cell Migration

doi: 10.64898/2026.03.13.711384

Figure Lengend Snippet: (A) Representative time-lapse images of migrating neutrophils expressing GFP-NMII under inhibition of ROCK (Y27632) or PI3K (LY294002). Rear and front regions are indicated by red and blue dashed outlines, respectively.(B) Quantification of NMII persistence at the cell front and rear across conditions. Plots show the fraction of cells maintaining NMII levels above a high-threshold intensity (≥1.1) for more than 50% of the migration time, revealing reduced rear NMII persistence after ROCK inhibition and reduced front NMII persistence after PI3K inhibition.(C) Migration phenotypes measured at the cell level. ROCK inhibition significantly reduces net displacement (ND), whereas PI3K inhibition increases turning probability without strongly affecting displacement.(D) Protrusion-level NMII metrics showing that LY294002 reduces front NMII engagement during protrusion activity, whereas Y27632 reduces rear NMII persistence.(E) Structural protrusion parameters across pharmacological conditions. PI3K inhibition shortens the stabilization phase of protrusions, whereas ROCK inhibition reduces protrusion expansion speed. (F) Transition probabilities between protrusion states under different perturbations. Control cells show balanced transitions between high- and low-directionality protrusions, whereas PI3K inhibition increases switching and ROCK inhibition stabilizes low-directionality protrusion states.(G) Conceptual model illustrating how pharmacological perturbations alter the temporal organization of protrusion states. Balanced alternation of protrusion states supports persistent migration in control cells, whereas altered transition patterns under PI3K or ROCK inhibition destabilize directional persistence.Data represent individual cells or protrusions from independent experiments as described in Methods. Statistical significance was determined using the tests indicated in the figure.

Article Snippet: Y27632, Ly294002 and ML-7 were from MedChem Express, Nitro-Blebbistatin was from Cayman, EHT186 was from R&D systems.

Techniques: Expressing, Inhibition, Migration, Activity Assay, Control

Journal: bioRxiv

Article Title: Spatially Distinct Myosin II Architectures Regulate Protrusion Dynamics and Directional Persistence during Immune Cell Migration

doi: 10.64898/2026.03.13.711384

Figure Lengend Snippet: (A) Organization of NMII in neutrophils migrating within three-dimensional collagen matrices. Maximum-intensity projections of fixed GFP-NMIIA neutrophils labeled with phalloidin (magenta) show NMII distribution at the leading edge and rear of the cell. Insets show higher-magnification views of the leading edge (1) and rear (2). Upper panels display maximum projections, middle panels show single optical slices highlighting NMII puncta (arrows), and lower panels show isosurface renderings illustrating the organization of NMII assemblies relative to cortical actin. (B) Organization of NMII during neutrophil migration in vivo. Single optical slices of representative cells show discrete NMII assemblies at the leading edge and cortical NMII bundles at the rear. (C) Visualization of NMII mini-filament organization using antibody labeling of the NMIIA tail domain together with GFP-NMIIA, revealing triskelion-like arrangements consistent with interconnected NMII mini-filaments. (D) Effects of pharmacological perturbations on NMII organization. Representative images of neutrophils treated with ROCK inhibitor (Y27632) or PI3K inhibitor (LY294002) and labeled for NMII (green) and F-actin (magenta). PI3K inhibition disrupts the lattice-like organization of NMII at the leading edge, whereas ROCK inhibition increases NMII density at the front and reduces cortical NMII at the rear. Scale bars as indicated.

Article Snippet: Y27632, Ly294002 and ML-7 were from MedChem Express, Nitro-Blebbistatin was from Cayman, EHT186 was from R&D systems.

Techniques: Labeling, Migration, In Vivo, Antibody Labeling, Inhibition

Journal: bioRxiv

Article Title: Steady-state epithelial apical flatness is characterized by MLCK morphodynamics and asynchronous Ca 2+ oscillations, but not underlying ECM geometry

doi: 10.1101/2025.11.21.688964

Figure Lengend Snippet: (A) Table showing drugs used to target myosin II, inhibitor function, and concentration. (B) Schematic showing the localization of myosin II interaction with actin in an MDCK monolayer. (C) A side view of a single optical section of a MDCK confluent monolayer treated with DMSO immunostained with ZO-1 (red), β-catenin (green), and filamentous actin dye, phalloidin (grey), and DNA DAPI (blue) counterstain. (D) As in (C) but treated with 30 µM blebbistatin, 50 µM Y27632 (E), and 100 µM ML-7 (F). (G) Individual cell measurements of macro-height for DMSO and drug-treated MDCK monolayers. Average macro-height for DMSO, blebbistatin, Y27632, and ML-7-treated cells was 12.20 µm ± 0.89 µm s.d., 12.11 µm ± 1.11 µm s.d., 11.61 µm ± 1.28 µm s.d., 12.20 µm ± 1.49 µm s.d., respectively (n=45 cells for each treatment). (H) As in (G) but of micro-height. Average micro-height for DMSO, blebbistatin, Y27632, and ML-7-treated cells was 1.30 µm ± 0.27 µm s.d., 2.44 µm ± 0.84 µm s.d., 2.72 µm ± 0.89 µm s.d., 1.84 µm ± 0.80 µm s.d., respectively. (I) Flatness threshold indices of macro-and micro-height of treated and control MDCK confluent monolayers. Note: All myosin II inhibitor treatments resulted in a loss of flatness. (Scale bars: 5µm)

Article Snippet: MDCK cells were treated with 10μM of cytochalasin D (C8273, Sigma), or 5μM of withaferin A (W4394, Sigma), or 16.5μM of nocodazole (M1404, Sigma), 30μM blebbistatin (B0560, Sigma) or 50μM Y27632 (sc-281642; Santa Cruz Biotechnology), 100μM ML-7 (ab120848; Abcam), dissolved in DMSO for 2 hr in an incubator at 37°C, 5% CO 2 before processing.

Techniques: Concentration Assay, Control