TY - JOUR
T1 - 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
AU - Ramkumar, Poornima
AU - Lee, Clement M.
AU - Moradian, Annie
AU - Sweredoski, Michael J.
AU - Hess, Sonja
AU - Sharrocks, Andrew D.
AU - Haines, Dale S.
AU - Reddy, E. Premkumar
N1 - Publisher Copyright:
© 2015 by The American Society for Biochemistry and Molecular Biology, Inc. Published in the U.S.A.
PY - 2015/12/4
Y1 - 2015/12/4
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84951774675&partnerID=8YFLogxK
U2 - 10.1074/jbc.M115.664649
DO - 10.1074/jbc.M115.664649
M3 - Article
C2 - 26468278
AN - SCOPUS:84951774675
SN - 0021-9258
VL - 290
SP - 29617
EP - 29628
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 49
ER -