Figure 7. Crumbs overexpression recapitulates the cell polarity defects of obe mutants. (A–D) Localization of Crumbs (anti-Crumbs antibody), centrosomes (Cnn), and Par-3 in wild type (A), embryos overexpressing Crumbs-PA (B) or Crumbs-PC (C), and crumbs11A22 maternal and zygotic mutants (crumbsm/z; D). All embryos are stage 7. Gal4/+ was the wild-type control. Moderate overexpression of Crumbs-PC induced Par-3 aggregation and centrosome mispositioning compared with wild type. Yellow boxes in C highlight representative cell interfaces. (E) Examples of edges with wild type (WT), fragmented, or aggregated Par-3 (white) localization. Left, examples from wild-type embryos. Middle and right, top example from Crumbs-PA and bottom two examples from Crumbs-PC. Yellow dots mark the endpoints of cell interfaces. (F) The percentage of apically mispositioned centrosomes was significantly increased in obe1/obe2 mutants (P < 0.0001) and in embryos overexpressing Crumbs-PC (P < 0.0001 by unpaired t test). Apically mispositioned centrosomes occurred to a lesser extent in crb mutants (P = 0.01) and Crumbs-PA–expressing embryos (P = 0.02). (G) The percentage of centrosomes in close proximity to adherens junctions was significantly increased in embryos overexpressing Crumbs-PC (P < 0.0001) and increased to a lesser extent in embryos overexpressing Crumbs-PA (P = 0.04). (H) The percentage of Par-3–positive edges with single Par-3 aggregates was significantly increased in embryos overexpressing Crumbs-PC (P = 0.0004), but was not affected in crb mutant or Crumbs-PA–expressing embryos (P > 0.5). (I) The percentage of Par-3–positive edges with Par-3 fragmentation was significantly increased in embryos expressing Crumbs-PC, Crumbs-PA, and crumbsm/z mutants (P < 0.0001). Boxes, 25–75th percentile. Whiskers, 5–95th percentile. Horizontal line, median. +, mean. Plot shows the distribution of mean values across embryos (19–49 cells analyzed per embryo in 6–10 embryos per genotype). The obe mutant embryos were the progeny of obe1/obe2 females crossed to obe2/+ males. (J) Model. A switch in isoform expression of the crumbs pre-mRNA in obelus mutants causes Par-3 aggregation, disrupting adherens junction localization and epithelial remodeling. Anterior left, dorsal up. Bars: (A–D) 10 µm; (E) 2 µm. See also Fig. S5.
Figure 7.

Crumbs overexpression recapitulates the cell polarity defects of obe mutants. (A–D) Localization of Crumbs (anti-Crumbs antibody), centrosomes (Cnn), and Par-3 in wild type (A), embryos overexpressing Crumbs-PA (B) or Crumbs-PC (C), and crumbs11A22 maternal and zygotic mutants (crumbsm/z; D). All embryos are stage 7. Gal4/+ was the wild-type control. Moderate overexpression of Crumbs-PC induced Par-3 aggregation and centrosome mispositioning compared with wild type. Yellow boxes in C highlight representative cell interfaces. (E) Examples of edges with wild type (WT), fragmented, or aggregated Par-3 (white) localization. Left, examples from wild-type embryos. Middle and right, top example from Crumbs-PA and bottom two examples from Crumbs-PC. Yellow dots mark the endpoints of cell interfaces. (F) The percentage of apically mispositioned centrosomes was significantly increased in obe1/obe2 mutants (P < 0.0001) and in embryos overexpressing Crumbs-PC (P < 0.0001 by unpaired t test). Apically mispositioned centrosomes occurred to a lesser extent in crb mutants (P = 0.01) and Crumbs-PA–expressing embryos (P = 0.02). (G) The percentage of centrosomes in close proximity to adherens junctions was significantly increased in embryos overexpressing Crumbs-PC (P < 0.0001) and increased to a lesser extent in embryos overexpressing Crumbs-PA (P = 0.04). (H) The percentage of Par-3–positive edges with single Par-3 aggregates was significantly increased in embryos overexpressing Crumbs-PC (P = 0.0004), but was not affected in crb mutant or Crumbs-PA–expressing embryos (P > 0.5). (I) The percentage of Par-3–positive edges with Par-3 fragmentation was significantly increased in embryos expressing Crumbs-PC, Crumbs-PA, and crumbsm/z mutants (P < 0.0001). Boxes, 25–75th percentile. Whiskers, 5–95th percentile. Horizontal line, median. +, mean. Plot shows the distribution of mean values across embryos (19–49 cells analyzed per embryo in 6–10 embryos per genotype). The obe mutant embryos were the progeny of obe1/obe2 females crossed to obe2/+ males. (J) Model. A switch in isoform expression of the crumbs pre-mRNA in obelus mutants causes Par-3 aggregation, disrupting adherens junction localization and epithelial remodeling. Anterior left, dorsal up. Bars: (A–D) 10 µm; (E) 2 µm. See also Fig. S5.

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