Fig. 5: Light-controlled regulation of cell motility and nuclear actin functions.

a Light-dependent nuclear export of MRTF-A in cells co-expressing iRIS-B and iB(actin). After cell fixation, MRTF-A was visualized using immunostaining. Confocal microscopy; scale bar, 10 µm. b MRTF-A localization in cells expressing iB(actin)–iRIS-B system, error bars represent SEM, n = 14–35 imaged cells. **p < 0.01, ns nonsignificant at p = 0.01 (two tailed, Student’s t test). Source data are provided as a Source Data file. c Schematic representation of light-regulation of non-tagged nuclear actin by iB(actin)–iRIS-B system. d Schematic representation of light-control of cytoplasmic actin by iB(actin)–iRIS-B system. e NIR light-triggered perturbation of endogenous cytoplasmic actin by iRIS-B and iB(actin). 740 nm illumination is indicated by red asterisk. Epifluorescence microscopy; scale bars, 20 µm. f Zoom-in views of the live-cell imaging of NIR light-triggered perturbation of endogenous cytoplasmic actin, as in e. Red asterisk indicates illumination by 740 nm light. Epifluorescence microscopy; scale bars 10 µm. g Absolute values of the rate of cell area change during time-lapse experiments. Optogenetic sequestration of endogenous actin to the plasma membrane significantly impacted cell edge motion dynamics as a function of time. Data are shown as the ratio of average results from the condition in which both iB(actin) and iRIS-B were co-expressed, from the negative control condition in which only the iRIS-B was expressed. Light-activation started at 600 s time point and remained for the entire duration of assays thereafter. Representative examples of edge tracking traces are shown in Supplementary Fig. 8. n = 29–35 protrusion/retractions pooled from 3–4 independent experiments, shown with SEM, **p < 0.01 (two tailed, Student’s t test). Source data are provided as a Source Data file.