Figure 5.
Deletion of dsc1 acts as an enhancer of iqgap2, which encodes a positive regulator of CK mechanoresponsiveness. (A) Representative growth curves from suspension culture of WT (blue), dsc1 (red), and iqgap2 (purple) single mutants and the iqgap2; dsc1 (gray) double mutant. Among these, iqgap2; dsc1 had the poorest growth, followed by iqgap2 and dsc1 single mutants and then WT. n = 6 per growth curve, bars represent SEM. (B) Growth rates quantified from the exponential growth phase had significant differences between these cell lines. P values were derived for ANOVA followed by Fisher’s LSD test. Number of samples analyzed, n = 6 from two independent experiments. (C) Representative images of DIC and nuclei stained by Hoescht of WT, iqgap2 and iqgap2; dsc1 mutant cell lines. Both iqgap2 and iqgap2; dsc1 had increased cell size and number of nuclei per cell as compared to WT. Scale bar, 40 μm and applies to all panels. (D) Quantification of the number of nuclei/cell revealed that iqgap2; dsc1 cells had the greatest amount of multinucleation. Note that this double mutant strain accumulated more than 20 nuclei in cells, a level not observed in any of the single mutants. The data shown represent two replicates, with 133–182 cells per cell line for each replicate. P value was calculated using the Comparison of Proportions test (*, P < 0.05; **, P < 0.001; ***, P < 0.0001). (E) Sequence of images show stages of cytokinesis of iqgap2 and iqgap2; dsc1 mutant cells. Images were collected on cells in the exponential growth phase. t = 0 is defined as when the videos start. Full videos are provided in the Supplemental materials (Videos 4, and 5). (F) The dot plot graph shows comparison of the effective cortical tension between WT, dsc1 null, iqgap2 null, and iqgap2; dsc1 double mutant cells. Effective cortical tension values for WT and dsc1 cells (shaded) are reproduced from Fig. 1 J to allow for side-by-side comparison. P values were calculated using Kruskal-Wallis followed by the Wilcoxon test. Number of cells analyzed, n = 4–10 from two independent experiments. (G) Summary diagram shows the genetic relationship between DscI and IQGAP2. This interaction indicates that both IQGAP2 and DscI are required for normal cytokinesis and that they work in parallel and/or collaboratively to ensure cytokinesis fidelity.

Deletion of dsc1 acts as an enhancer of iqgap2, which encodes a positive regulator of CK mechanoresponsiveness. (A) Representative growth curves from suspension culture of WT (blue), dsc1 (red), and iqgap2 (purple) single mutants and the iqgap2; dsc1 (gray) double mutant. Among these, iqgap2; dsc1 had the poorest growth, followed by iqgap2 and dsc1 single mutants and then WT. n = 6 per growth curve, bars represent SEM. (B) Growth rates quantified from the exponential growth phase had significant differences between these cell lines. P values were derived for ANOVA followed by Fisher’s LSD test. Number of samples analyzed, n = 6 from two independent experiments. (C) Representative images of DIC and nuclei stained by Hoescht of WT, iqgap2 and iqgap2; dsc1 mutant cell lines. Both iqgap2 and iqgap2; dsc1 had increased cell size and number of nuclei per cell as compared to WT. Scale bar, 40 μm and applies to all panels. (D) Quantification of the number of nuclei/cell revealed that iqgap2; dsc1 cells had the greatest amount of multinucleation. Note that this double mutant strain accumulated more than 20 nuclei in cells, a level not observed in any of the single mutants. The data shown represent two replicates, with 133–182 cells per cell line for each replicate. P value was calculated using the Comparison of Proportions test (*, P < 0.05; **, P < 0.001; ***, P < 0.0001). (E) Sequence of images show stages of cytokinesis of iqgap2 and iqgap2; dsc1 mutant cells. Images were collected on cells in the exponential growth phase. t = 0 is defined as when the videos start. Full videos are provided in the Supplemental materials (Videos 4, and 5). (F) The dot plot graph shows comparison of the effective cortical tension between WT, dsc1 null, iqgap2 null, and iqgap2; dsc1 double mutant cells. Effective cortical tension values for WT and dsc1 cells (shaded) are reproduced from Fig. 1 J to allow for side-by-side comparison. P values were calculated using Kruskal-Wallis followed by the Wilcoxon test. Number of cells analyzed, n = 4–10 from two independent experiments. (G) Summary diagram shows the genetic relationship between DscI and IQGAP2. This interaction indicates that both IQGAP2 and DscI are required for normal cytokinesis and that they work in parallel and/or collaboratively to ensure cytokinesis fidelity.

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