Research ArticleCELL BIOLOGY

Stick-slip dynamics of cell adhesion triggers spontaneous symmetry breaking and directional migration of mesenchymal cells on one-dimensional lines

See allHide authors and affiliations

Science Advances  03 Jan 2020:
Vol. 6, no. 1, eaau5670
DOI: 10.1126/sciadv.aau5670
  • Fig. 1 1D single-cell migration assay based on soft micropatterning and TFM mimics complex 3D fibrillar in vivo migration.

    (A) Polyacrylamide gel (40 kPa) with RPE1 cells (blue, nucleus staining) on top of 2-μm micropatterned fibronectin lines (red). (B) Bright-field, actin cytoskeleton, and bead imaging of RPE1 on a 2-μm line allowed extracting morphometric and mechanical parameters simultaneously. (C) Time sequence of RPE1 cell migrating on fibronectin lines and (D) its associated stress profile extracted via TFM (dotted white line, cell outline; color-coded stress profile depending on the direction of applied traction forces F: red in and cyan against the direction of migration. Scale bars, 10 μm).

  • Fig. 2 RPE1 cells exhibit intermittent migration following a stick-slip motion.

    (A) Scheme of the force asymmetry analysis: The normalized quadrupole was extracted from the 1D projection of the stress profile of an adherent cell (color-coded stress map and 1D profile depending on the direction of applied traction forces F exerted: red in and cyan against the direction of migration). Dynamic measurements revealed a symmetric spatial force profile during static spreading and an asymmetric distribution during migration phases. Inset: average force asymmetry during static and mobile phases of several cells (n = 10). ****P < 0.0001 (unpaired, two-tailed t test). (B) Cell length and total force correlation: increase during spreading phase and decrease during migration. (C) Referenced kymograph of RPE1 cells stably expressing vinculin-eGFP showing a continuous attachment of the front, while adhesions in the rear detached and reattached during one migration cycle (scale bar, 10 μm). Tracking the front, rear, and nucleus position over time could further represent this destabilization of the rear. (D) Deduced scheme of the proposed stick-slip migration mechanism: During nonmotile spreading (stick), the cell builds up a high traction force that eventually will overcome adhesion strength in the perspective rear of the cell. Upon the retraction of the rear, the cell shortens and lowers its mechanical interaction with the substrate to initiate migration (slip). (E) Schematic of the model and parameters as defined in the text. (F) Phase diagram of dynamic behaviors predicted by the model, as a function of the actin turnover rate λ and phenomenological parameter α (arbitrary units). Dashed lines show different values of the maximal contractile force Fmax = χαλ. (G) Example of stick-slip dynamics predicted by the model. Dynamical eqs. S2 and S3 are solved numerically with vm = 0.5, vp= 0.5, λ = 1, μ = 1, α = 1 (arbitrary units). Blue, orange, and brown line show rear, nucleus, and front position over time, respectively. Green line depicts the relative traction force level F.

  • Fig. 3 RhoA optogenetic control of cellular force symmetry breaking.

    (A) Schematic representation of light-induced Cry2-CIBN dimerization and local RhoA activation due to its close proximity to its upstream regulator optoGEF_RhoA. Bright-field and actin imaging and quantification showed the light-induced migration away from the photoactivation area (blue square), which is characterized by a transient front-rear polarity and actin asymmetry (dashed line, nucleus position at t0). (B) Local and global force response of the light-induced rear and of the whole cell, respectively, showed a transient local contractility increase at the perspective rear followed by a global decrease of the mechanical cell-substrate interaction. (C) Cells stably expressing vinculin-iRFP revealed local adhesion reinforcement within the photostimulated area followed by a subsequent adhesion detachment. Dashed line indicates nucleus position at t0. Scale bar, 10 μm. a.u., arbitrary units.

  • Fig. 4 Adhesiveness and contractility control the migratory behavior of NIH-3T3 and RPE1 cells.

    (A) Comparison of instantaneous migration speed, total force, cell length, and individual adhesion size of RPE1 and NIH-3T3 cells. (B) FRAP experiments of adhesions located at one cell edge were modeled with a biexponential fit to extract a fast and slow component representing mobile vinculin within the cytoplasm and slow vinculin bound to adhesions. ROI, region of interest. (C and D) Altering the migratory behavior of RPE1 and NIH-3T3 using 1 μM pF573,228 to inhibit and 3 μM blebbistatin to trigger migration, respectively. Shown are measured parameters relevant for stick-slip migration: average migration speed, total force, cell length, and individual adhesion size. Statistical significance tested with unpaired two-tailed t test. Scatter plots with means and SD. Box plots from minimum and maximum values with the means and SD. Number n of analyzed cells per condition indicated on the respective graph figures. ****P<0.0001; **P<0.01; ns, not significant.

  • Fig. 5 The inverse relation between cell length and speed.

    (A) Experimentally deduced phase diagram using a pharmacological approach to alter the migratory behavior of RPE1 and NIH-3T3 cell (error bars show the SD from the mean). (B) Length-speed relation validated by analyzing several cell types coming from the cell race data (one color used per cell type; gray line, linear fit of all data points). (C) Summary showing how cell contractility, and therefore adhesiveness and cell length, control cellular migration.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/1/eaau5670/DC1

    Supplementary Text

    Fig. S1. Polarization of the actin cytoskeleton.

    Fig. S2. Mechanical interaction between the cell and its environment decreases upon the initiation of migration.

    Fig. S3. Force-length correlation during stick-slip migration.

    Movie S1. Adhesion dynamics of RPE1 and NIH-3T3 cells.

  • Supplementary Materials

    The PDFset includes:

    • Supplementary Text
    • Fig. S1. Polarization of the actin cytoskeleton.
    • Fig. S2. Mechanical interaction between the cell and its environment decreases upon the initiation of migration.
    • Fig. S3. Force-length correlation during stick-slip migration.
    • Legend for movie S1

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.avi format). Adhesion dynamics of RPE1 and NIH-3T3 cells.

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article