Journal: bioRxiv
Article Title: CIP2A is required for mitotic recruitment of the SLX1/XPF/MUS81 tri-nuclease complex to replication stress-induced DNA lesions to maintain genome integrity
doi: 10.1101/2025.04.03.647079
Figure Lengend Snippet: (A) CIP2A is predicted to form a stable homodimer, involving a globular domain with a long coiled-coil. Two predicted binding sites of TOPBP1 are indicated, along with an uncertain, and possibly flexible, position of the N-terminal regions onto the coiled-coil shaft. (B) A cartoon and surface representation of the predicted CIP2A:CIP2A dimer structure with two copies of TOPBP1 755-860, and a magnification of predicted TOPBP1:CIP2A binding interfaces. (C) Schematic representation of full length (1-905) CIP2A (WT), the reported dimerization site (L533), the PLK1 phosphorylation site (S904), the globular domain (1-617), the alpha-helical coiled-coil (618-876), and the unstructured C-terminal domain (877-905). Schematic representation of V5-tagged CIP2A variants: CIP2A lacking the unstructured C-terminal domain (‘CIP2A-ΔC’), CIP2A with only globular domain (‘CIP2A-Glob’), CIP2A lacking the alpha-helical coiled-coil (‘CIP2A-ΔCC’) and CIP2A lacking the globular domain (‘CIP2A-ΔGlob’). (D) Quantification of V5 foci and TOPBP1 foci per mitotic cell in RPE1 TP53 -/- CIP2A -/- cl#1 cells reconstituted with indicated CIP2A-V5 cDNAs, treated with APH (200 nM, 20 h). Individual values, medians and interquartile range of three experiments with n>30 cells per experimental condition are plotted. P-values were calculated using ordinary one-way ANOVA with Šidák’s multiple comparisons test on the medians per experiment. (E) Quantification of micronuclei per cell in parental RPE1 TP53 -/- cells, CIP2A -/- cl#1 cells and CIP2A -/- cl#1 cells reconstituted with indicated CIP2A cDNAs, treated with APH (200 nM, 20 h). Individual values, medians and interquartile range of at least three experiments with n≥85 cells per experimental condition are plotted. P-values were calculated using ordinary one-way ANOVA with Dunnett’s multiple comparison test. (F) CIP2A -/- cells reconstituted with CIP2A-WT, CIP2A-S904A or CIP2A-ΔC were treated with APH (200 nM, 20 h), and stained for DAPI (blue), V5 (red) and SLX4 (green). Scale bar represents 10 µm. (G) Quantification of SLX4 foci per mitotic cell in CIP2A -/- cl#1 reconstituted with indicated mutants for cells treated as described in panel F. Individual values, medians and interquartile range of three experiments with n>30 cells per experimental condition are plotted. P-values were calculated using ordinary one-way ANOVA with Šidák’s multiple comparisons test on the medians per experiment. (H) Quantification of MUS81 foci per mitotic cell in CIP2A -/- cl#1 reconstituted with either CIP2A-WT, CIP2A-S904A or CIP2A-ΔC after treatment with APH (200 nM, 20 h). Individual values, medians and interquartile range of three experiments with n>30 cells per experimental condition are plotted. P-values were calculated using ordinary one-way ANOVA with Šidák’s multiple comparisons test on the medians per experiment. (I) Representative STED microscopy images of DAPI (blue), V5 (green) and TOPBP1 (red) structures in CIP2A -/- cells reconstituted with CIP2A-WT for the three classes of structures (unstructured, loop-containing, and filamentous) after APH treatment (200 nM, 20 h). Scale bar represents 5 µm (confocal) or 500 nm (STED). STED images are Wiener deconvolved. Raw data is shown in Suppl. Fig. 7D (J) Representative STED microscopy images of DAPI (blue), V5 (green) and TOPBP1 (red) structures in CIP2A -/- cells reconstituted with CIP2A-ΔC for the three classes of structures (unstructured, loop-containing, and filamentous) after APH treatment (200 nM, 20 h). Scale bar represents 5 µm (confocal) or 500 nm (STED). STED images are Wiener deconvolved. Raw data is shown in Suppl. Fig. 7E. (K) Quantification of unstructured, loop-containing or loop-like, and filamentous or filament-like structures in CIP2A -/- cells reconstituted with either CIP2A-WT or CIP2A-ΔC. Bars represent the mean and SEM of three experiments with n>15 structures per experimental condition. P-values were calculated using two-tailed unpaired t-test.
Article Snippet: Full length CIP2A was cloned from pcDNA3.1/CIP2A(1-905) WT V5 His (Addgene #119287), which was a gift from Jukka Westermarck , into retroviral pMSCV-blast which was a gift from David Mu (Addgene #75085) , and subsequently different CIP2A mutations were generated in this pMSCV plasmid.
Techniques: Binding Assay, Phospho-proteomics, Comparison, Staining, Microscopy, Two Tailed Test