Collective cell migration is important in various physiological processes, including wound healing, morphogenesis and cancer migration. Central to the orchestration of collective cell migration is the Adherens Junction (AJ), a pivotal structure regulating cell cohesion and migration dynamics during tissue remodeling.
However, the understanding of how the structure and dynamic properties of the actin cortex influence junction plasticity remains relatively limited. Similarly, the intricate orchestration of molecular mechanisms governing the mechanical properties of cortical actin remains incompletely understood.
This article presents evidence that EGFR dephosphorylation reduced the dynamics of cell junction formation.
Fig 1. Positive feedback loop between atypical EGFR phosphorylation and cell junction deformation.
(A) Schematics of the experiment for cell migration with or without EGFR inhibition (Erlotinib at 1 μμM). (B) Quantification of individual junction elongation velocities in the patches (mean ± s.d.) nCtrl = 36 junctions and nErlotinib = 29 junctions from 3 independent experiments, two-tailed unpaired t test, P< 0.0001. (C) Schematics of the experiment for cell arrest by dextran addition. (D) Western blot and its quantification of EGFR phosphorylated states (Y845) before and after cell arrest from 4 independent experiments, two-tailed unpaired t test, P= 0.029. (E) Experimental setup schematics (Left) and segmented contours quantification (Right) of cell mosaically expressing RUSH-EGFR before and after its release from the endoplasmic reticulum. (F) Quantifications of junction elongation velocities upon the release of EGFR, under control and pEGFR-inhibited conditions. nRush/Ctrl = 28 junctions and nRush/Erlotinib = 15 junctions from 3 independent experiments, two-tailed paired t test, PRush/Ctrl < 0.001, PRush/Erlotinib = 0.52. (G) Schematics of the physical induction of cell elongation around obstacles (Left). (H) Quantifications of apical pEGFR-Y845 intensity around obstacles (mean ± s.d. nBulk = 50 junctions and nObstacle = 48 junctions from 3 independent experiments, two-tailed unpaired t test, P< 0.0001.) (I) Diagram of a positive feedback loop between apical EGFR phosphorylation and cell junction deformation.
The impact of EGFR phosphorylation on the turnover rate of junction actin was determined using Fluorescence Recovery After Photobleaching (FRAP). The junctions in confluent monolayers, cells surrounding obstacles, and subconfluent patches with or without EGFR inhibition were compared (Fig. 2H). In all cases, it was observed that there was a deceleration in actin turnover when pEGFR levels were lower. Additionally, the junctional tension was tested by assessing fast actin recoil following laser ablation. No substantial difference was observed, proving that pEGFR does not regulate tension in this specific context.
Fig. 2H Rheological properties of junctional actin.
The full article can be accessed here.
