Journal: The Journal of Biological Chemistry
Article Title: Phosphorylation of Targeting Protein for Xenopus Kinesin-like Protein 2 (TPX2) at Threonine 72 in Spindle Assembly *
doi: 10.1074/jbc.M114.591545
Figure Lengend Snippet: Effects of GFP-TPX2 T72A on the polarity of mitotic spindles in HeLa cells with or without endogenous TPX2. A, representative photographs of mitotic HeLa cells at prometaphase and metaphase with monopolar, bipolar, and multipolar mitotic spindle poles. Scale bar, 10 μm. B, Western blots showing the levels of endogenous TPX2, GFP-TPX2 WT, and GFP-TPX2 T72A in cells with intact levels of TPX2. C, bar graphs showing the number of cells with different mono-, bi-, or multipolar mitotic spindles in each group. Cells with mitotic spindles were fixed and stained with Cy3-conjugated tubulin for MT visualization. GFP-TPX2 T72A expression results in a significant increase in the percentage of cells with multipolar spindles in the presence of endogenous TPX2. ANOVA comparing the three groups shows high significance with p < 0.001. Neuman-Keuls test was used to compare each group: GFP (1.49 ± 0.47) versus T72A (12.72 ± 2.10), p < 0.001; TPX2 WT (3.36 ± 0.40) versus T72A (12.72 ± 2.10), p < 0.001; group (mean ± S.E.); ***, p < 0.001; NS, not significant (GFP versus TPX2). At least 100 cells for each set of experiments were used for quantification, 5 independent experiments were performed. Error bars indicate S.E. D, Western blots showing the levels of endogenous TPX2, GFP-TPX2 WT, and GFP-TPX2 T72A in HeLa cells co-transfected with GFP-vector, GFP-TPX2 WT, or GFP-TPX2 T72A together with TPX2 siRNA targeting the 3′ UTR of TPX2 mRNA. E, bar graphs showing the number of cells with different mono-, bi-, or multipolar mitotic spindles in each group. Cells with mitotic spindles were fixed and stained with Cy3-conjugated tubulin for MT visualization. Knockdown of TPX2 in GFP-transfected cells results in a significant 5.4% increase in multipolar spindles versus control cells without TPX2 depletion. GFP-TPX2 T72A expression produces an even greater 9.8 and 7.5% increase in the percentage of cells with multipolar spindles when compared with GFP/TPX2 siRNA and GFP-TPX2 WT/TPX siRNA, respectively. n = 3, ANOVA test was used the compare the four groups (p < 0.01). The Neuman-Keuls test was used to compare the following groups: control (with control siRNA) (2.43 ± 0.41) versus GFP (7.94 ± 1.5), p < 0.05; GFP (7.94 ± 1.5) versus TPX2 WT (10.13 ± 1.2), NS; WT (10.13 ± 1.2) versus T72A (17.67 ± 3.2), p < 0.05; GFP (7.94 ± 1.5) versus T72A (17.67 ± 3.2), p < 0.05; group (mean ± S.E.); *, p < 0.05; NS, not significant. n = at least 500 cells for each set of experiments; 3 independent experiments were performed. Error bars indicate S.E.
Article Snippet: Western blot analysis was performed with reaction products using TPX2 (clone 184, Novus Biologicals), Thr(P) 72 , Cdk1, and Cdk2 Abs. . RNA Interference Sequences Two unique TPX2-specific siRNA oligos were used to knock down endogenous TPX2.
Techniques: Western Blot, Staining, Expressing, Transfection, Plasmid Preparation, Knockdown, Control