Skip to main content
. Author manuscript; available in PMC: 2023 Apr 6.
Published in final edited form as: Nat Cell Biol. 2022 Oct 6;24(10):1499–1515. doi: 10.1038/s41556-022-00997-7

Figure 5. Globally lowering negative surface charge of the membrane can abolish the pre-existing polarity by consistently generating new protrusions from the back-state regions.

Figure 5.

(A, B) Time-lapse snapshots (A) and time-stack (B) demonstrating cell morphology and migration mode changes in a polarized Dictyostelium cell, upon recruitment of Opto-ACTU+. Cells were co-expressing Opto-ACTU+ and cAR1-CIBN. Time in seconds. 488 nm laser switched ON globally at t=0s. Yellow arrowheads in (B): newly generated protrusions. Note that Opto-ACTU+ is consistently depleted in the protrusions. (C-F) Quantification of cell morphology and migration mode changes in terms of cell circularity index (C), cell tracks (D), migration speed (E), and new protrusion formation frequency (F) upon Opto-ACTU+ recruitment (n=25 cells). Data are mean ± SEM in (C). In (D-F), for either before or after recruitment, each cell was tracked for nf=40 frames (8 sec/frame was the image acquisition frequency). Tracks were reset to the same origin in (D). For pairwise comparison, tracks are color-coded in (D) and data from same cell are connected by gray lines in (E) and (F). All p-values by Mann-Whitney-Wilcoxon test. (G) Two representative examples of temporally color-coded cell outlines showing cell morphology and migratory mode before 488nm was turned on, during 488nm kept on, and after 488nm was switched off. (H) Schematic proposing how Opto-ACTU+ recruitment changes cell morphology and migratory mode. Opto-ACTU+ is recruited globally as expected (I to II); however, presumably due to its positive charge, it quickly accumulates along the back regions of the cell (III). Consequently, new protrusions are elicited from these back regions and the cell begins to lose polarity (IV and V). And at the same time, as some areas of erstwhile back regions are converted to front, Opto-ACTU+ redistributes again to the newly formed back regions (IV to VII). This in turn generates fresh protrusions there and this entire cycle is repeated (shown in arrows between VI and VII). As a result, protrusions are generated randomly, migration becomes impaired, and pre-existing polarity is abrogated.

Source numerical data are available in source data.