The serine/threonine protein phosphatase 5 (PP5) regulates multiple cellular signaling networks. A number of cellular factors, including heat shock protein 90 (Hsp90), promote the activation of PP5. However, it is unclear whether post-translational modifications also influence PP5 phosphatase activity. Here, we show an "on/off switch" mechanism for PP5 regulation. The casein kinase 1δ (CK1δ) phosphorylates T362 in the catalytic domain of PP5, which activates and enhances phosphatase activity independent of Hsp90. Overexpression of the phosphomimetic T362E-PP5 mutant hyper-dephosphorylates substrates such as the co-chaperone Cdc37 and glucocorticoid receptor in cells. Our proteomic approach revealed that the tumor suppressor von Hippel-Lindau protein (VHL) interacts with and ubiquitinates K185/K199-PP5 for proteasomal degradation in a hypoxia- and prolyl-hydroxylation-independent manner. Finally, VHL-deficient clear cell renal cell carcinoma (ccRCC) cell lines and patient tumors exhibit elevated PP5 levels. Downregulation of PP5 causes ccRCC cells to undergo apoptosis, suggesting a prosurvival role for PP5 in kidney cancer.
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http://dx.doi.org/10.1016/j.celrep.2017.10.074 | DOI Listing |
Cell Commun Signal
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Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, 100191, China.
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School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong S.A.R., China.
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CECAD Cluster of Excellence, University of Cologne, Cologne, Germany.
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Key Laboratory of Medicine, Ministry of Education, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University; Wenzhou, Zhejiang 325035, China; Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou, Zhejiang 325053, China. Electronic address:
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Department of In Vitro Carcinogenesis and Cellular Chemotherapy, Chittaranjan National Cancer Institute, 37, S. P. Mukherjee Road, Kolkata 700026, India. Electronic address:
Histone deacetylases (HDACs) play a critical role in chromatin remodelling and modulating the activity of various histone proteins. Aberrant HDAC functions has been related to the progression of breast cancer (BC), making HDAC inhibitors (HDACi) promising small-molecule therapeutics for its treatment. Hydroxamic acid (HA) is a significant pharmacophore due to its strong metal-chelating ability, HDAC inhibition properties, MMP inhibition abilities, and more.
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