title: JNK-associated Leucine Zipper Protein Functions as a Docking Platform for Polo-like Kinase 1 and Regulation of the Associating Transcription Factor Forkhead Box Protein K1.
abstract: JLP (JNK-associated leucine zipper protein) is a scaffolding protein that interacts with various signaling proteins associated with coordinated regulation of cellular process such as endocytosis, motility, neurite outgrowth, cell proliferation, and apoptosis. Here we identified PLK1 (Polo-like kinase 1) as a novel interaction partner of JLP through mass spectrometric approaches. Our results indicate that JLP is phospho-primed by PLK1 on Thr-351, which is recognized by the Polo box domain of PLK1 leading to phosphorylation of JLP at additional sites. Stable isotope labeling by amino acids in cell culture and quantitative LC-MS/MS analysis was performed to identify PLK1-dependent JLP-interacting proteins. Treatment of cells with the PLK1 kinase inhibitor BI2536 suppressed binding of the Forkhead box protein K1 (FOXK1) transcriptional repressor to JLP. JLP was found to interact with PLK1 and FOXK1 during mitosis. Moreover, knockdown of PLK1 affected the interaction between JLP and FOXK1. FOXK1 is a known transcriptional repressor of the CDK inhibitor p21/WAF1, and knockdown of JLP resulted in increased FOXK1 protein levels and a reduction of p21 transcript levels. Our results suggest a novel mechanism by which FOXK1 protein levels and activity are regulated by associating with JLP and PLK1.
authors.affiliation: From the Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029.
authors.forename: Poornima
authors.initials: P
authors.lastname: Ramkumar
authors.affiliation: From the Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029.
authors.forename: Clement M
authors.initials: CM
authors.lastname: Lee
authors.affiliation: the Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, California 91125, and.
authors.forename: Annie
authors.initials: A
authors.lastname: Moradian
authors.affiliation: the Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, California 91125, and.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Sweredoski
authors.affiliation: the Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, California 91125, and.
authors.forename: Sonja
authors.initials: S
authors.lastname: Hess
authors.affiliation: the Faculty of Life Sciences, University of Manchester, Manchester M13 9PL, United Kingdom.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Sharrocks
authors.affiliation: the Fels Institute for Cancer Research and Molecular Biology, Temple University, Philadelphia, Pennsylvania 19122.
authors.forename: Dale S
authors.initials: DS
authors.lastname: Haines
authors.affiliation: From the Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, ep.reddy@mssm.edu.
authors.forename: E Premkumar
authors.initials: EP
authors.lastname: Reddy
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D050256:Antimitotic Agents / Q000737:chemistry; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D008938:Mitosis; D010766:Phosphorylation; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011621:Pteridines / Q000737:chemistry; D015398:Signal Transduction; D053719:Tandem Mass Spectrometry; D000097869:Polo-Like Kinase 1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D050256:Antimitotic Agents; D018797:Cell Cycle Proteins; D051858:Forkhead Transcription Factors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D011621:Pteridines; D000097869:Polo-Like Kinase 1; C518477:BI 2536; C495879:FOXK1 protein, human; C111047:SPAG9 protein, human; C468928:Spag9 protein, mouse
keywords: FOXK1; JLP; PLK1; mitosis; phosphorylation; protein-protein interaction; scaffold protein; serine/threonine protein kinase; transcription factor