Phosphorylation of Targeting Protein for Xenopus Kinesin-like Protein 2 (TPX2) at Threonine 72 in Spindle Assembly
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- Title
- Phosphorylation of Targeting Protein for Xenopus Kinesin-like Protein 2 (TPX2) at Threonine 72 in Spindle Assembly
- Authors
- Shim, SY; de Castro, IP; Neumayer, G; Wang, J; Park, SK; Sanada, K; Nguyen, MD
- Date Issued
- 2015-04-03
- Publisher
- American Society for Biochemistry and Molecular Biology Inc.
- Abstract
- The human ortholog of the targeting protein for Xenopus kinesin-like protein 2 (TPX2) is a cytoskeletal protein that plays a major role in spindle assembly and is required for mitosis. During spindle morphogenesis, TPX2 cooperates with Aurora A kinase and Eg5 kinesin to regulate microtubule organization. TPX2 displays over 40 putative phosphorylation sites identified from various high-throughput proteomic screenings. In this study, we characterize the phosphorylation of threonine 72 (Thr(72)) in human TPX2, a residue highly conserved across species. We find that Cdk1/2 phosphorylate TPX2 in vitro and in vivo. Using homemade antibodies specific for TPX2 phosphorylated at Thr(72), we show that this phosphorylation is cell cycle-dependent and peaks at M phase. Endogenous TPX2 phosphorylated at Thr(72) does not associate with the mitotic spindle. Furthermore, ectopic GFP-TPX2 T72A preferentially concentrates on the spindle, whereas GFP-TPX2 WT distributes to both spindle and cytosol. The T72A mutant also increases the proportion of cells with multipolar spindles phenotype. This effect is associated with increased Aurora A activity and abnormally elongated spindles, indicative of higher Eg5 activity. In summary, we propose that phosphorylation of Thr(72) regulates TPX2 localization and impacts spindle assembly via Aurora A and Eg5.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/26879
- DOI
- 10.1074/JBC.M114.591545
- ISSN
- 0021-9258
- Article Type
- Article
- Citation
- Journal of Biological Chemistry, vol. 290, no. 14, page. 9122 - 9134, 2015-04-03
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