MASPs stabilize dynamics in TJ permeability. (A) Snapshots of the ZnUMBA assay using MASP-qKO cells mixed with Ctrl cells labeled with nuclear mCherry (pseudocolor blue). FluoZin-3 signals in the qKO cell region (yellow arrows) and Ctrl cell region (white arrows) are shown with a Gem lookup table. Scale bar, 10 µm. (B) FluoZin-3 signals at each time point are shown in orange. Cell–cell junctions are indicated with gray lines. Blue areas indicate the qKO cells. All signals observed during imaging are shown in the bottom-right panel. (C) Quantification of the leak sizes. A set of interconnected cell–cell junctions with FluoZin-3 signal are regarded as a single leak. The number of cell–cell junctions in each leak was counted and plotted. The leaks were divided into two categories: leaks located within or next to the MASP-qKO cells and leaks in the Ctrl cells. 25, 50, and 75 percentiles are shown (magenta; n = 517 [within or next to MASP-qKO] and 385 [Ctrl]). ***, P < 0.001 (two-tailed Welch’s t test). (D) Quantification of the duration of the leaks. Cell–cell junctions were categorized into four groups: qKO-qKO (n = 144), qKO-Ctrl (n = 218), Ctrl-Ctrl next to qKO (n = 130), and Ctrl-Ctrl not neighboring to qKO (n = 400). *, P < 0.05 (two-tailed Welch’s t test with Bonferroni’s correction). (E) Frequency of leaks. *, P < 0.05; ***, P < 0.001 (Steel-Dwass test). Source data are available for this figure: SourceData F6.