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Global assessment of Plk1 network dynamics identifies inhibition of PP6 as a mechanism to promote Aurora A activity

ABSTRACT: Polo-like kinase 1 (Plk1) is an essential protein kinase that promotes faithful mitotic progression in eukaryotes. Plk1 subcellular localization and substrate interactions are tightly controlled and require binding of Plk1 to phosphorylated sequences. Here, we use quantitative proteomics to identify phosphorylation-dependent interactions within the Plk1 network in human mitotic HeLa cells using kinase inhibitors and a Plk1 mutant deficient in phosphorylation-dependent substrate binding. We find that many interactions are abolished upon kinase inhibition; however, a subset are protected from phosphatase opposition or are unopposed, resulting in persistent Plk1-substrate interactions. This subset includes Phosphoprotein Phosphatase 6 (PP6), whose activity towards Aurora kinase A (AURKA) is inhibited by Plk1. This Plk1-PP6 interaction creates a feedback loop that coordinates and reinforces the activities of Plk1 and AURKA during mitotic entry and is terminated by Plk1 degradation during mitotic exit. Collectively, this work provides a cellular mechanism for the observed regulation of AURKA by Plk1.

INSTRUMENT(S): LTQ Orbitrap, Q Exactive Plus

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Scott Gerber Arminja Kettenbach

PROVIDER: MSV000082147 | MassIVE | Fri Mar 09 13:58:00 GMT 2018

SECONDARY ACCESSION(S): PXD009168

REPOSITORIES: MassIVE

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Aurora B opposes PP1 function in mitosis through phosphorylation of the conserved RVxF binding motif in PP1 regulatory proteins

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Aurora kinase B-dependent phosphorylation regulates caspase-2 activity and function

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2017-12-01 | PXD008316 | Pride

Small changes in phospho-occupancy at the kinetochore-microtubule interface drive mitotic fidelity

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The investigational Aurora kinase A inhibitor MLN8237 induces defects in cell viability and cell cycle progression in mouse bladder cancer cells in vitro and in vivo

Project description:PURPOSE: Despite over 70,000 new cases of bladder cancer in the United States annually, patients with advanced disease have a poor prognosis due to limited treatment modalities. We evaluate the role of Aurora A, identified as an upregulated candidate molecule in bladder cancer, in regulating bladder tumor growth. EXPERIMENTAL DESIGN: Gene expression in human bladder cancer samples was evaluated using RNA microarray and reverse-transcriptase PCR. The specific Aurora kinase A inhibitor MLN8237 (Millennium) was used to determine effects on bladder cancer cell growth using in vitro and in vivo models using malignant T24 and UM-UC-3 and papilloma-derived RT4 bladder cells. RESULTS: Urothelial carcinoma upregulates a set of 13 mitotic spindle associated transcripts, as compared to normal urothelium, including MAD2L1 (7.6-fold), BUB1B (8.8-fold), Aurora kinases A (5.6-fold) and Aurora kinase B (6.2-fold). Application of MLN8237 (10nM-1µM) to the human bladder tumor cell lines T24 and UM-UC-3 induced dose-dependent G2 cell cycle arrest, aneuploidy, mitotic spindle abnormalities, and apoptosis. MLN8237 arrested tumor growth when administered orally over 4 weeks in a mouse bladder cancer xenograft model (p<0.05). Finally, in vitro combination of MLN8237 with either paclitaxel or gemcitabine produced schedule-dependent synergistic antiproliferative effects in T24 cells when administered sequentially. CONCLUSIONS: Mitotic spindle checkpoint dysfunction is a common characteristic of human urothelial carcinoma, and can be exploited with pharmacologic Aurora A inhibition. Future studies that explore the mechanisms of spindle checkpoint failure in bladder cancer and evaluate the therapeutic role of Aurora kinases for bladder cancer patients would be of value. Tissue samples with urothelial cell carcinoma from bladder as well as normal references were collected and the gene expression profiles were compared. No technical replicates.

2013-05-01 | E-GEOD-42089 | biostudies-arrayexpress

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