title: 14-3-3ζ regulates nuclear trafficking of protein phosphatase 1α (PP1α) in HEK-293 cells.
abstract: Protein phosphatase 1 (PP1) is one of the major Ser/Thr phosphatases in mammalian cells. There are four isoforms of PP1 namely, PP1α, PP1β/δ, PP1γ1 and PP1γ2. PP1γ and PP1β translocate to the nucleus by binding to a co-transporter that contains a nuclear localization signal. The mechanism by which PP1α shuttles between the nucleus and the cytosol is not known. In this study, we found that PP1α co-immunoprecipitates with 14-3-3ζ from HEK-293 cell lysates. By co-immunoprecipitation and GST pull-down assay, we determined that 14-3-3ζ binds to both PP1α (WT) and PP1α (T320A), and that phosphorylation of PP1α is not required for binding. Using PP1α deletion mutants, we located the 14-3-3ζ binding region within PP1α residues 159-279. An in vitro assay showed that 14-3-3ζ does not affect PP1α activity. When HEK-293 cells expressing PP1α and 14-3-3ζ were subjected to subcellular fractionation, the ratio of cytosolic vs. nuclear PP1α was significantly higher in cells expressing PP1α and 14-3-3ζ than those expressing PP1α alone. In cells expressing a dominant negative 14-3-3ζ (K49E), PP1α accumulated in the nucleus. Our results show that 14-3-3ζ binds to PP1α and causes its retention in the cytosol which suggests that 14-3-3ζ regulates nuclear trafficking of PP1α in mammalian cells.
authors: The Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital and the Department of Neurology and Neurosurgery, McGill University, H3T 1E2, Canada.
authors: Myrka
authors: M
authors: Jérôme
authors: The Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital and the Department of Neurology and Neurosurgery, McGill University, H3T 1E2, Canada. Electronic address: hemant.paudel@mcgill.ca.
authors: Hemant K
authors: HK
authors: Paudel
mesh_terms: D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D021581:Active Transport, Cell Nucleus; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D010766:Phosphorylation; D054645:Protein Phosphatase 1 / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D054645:Protein Phosphatase 1
keywords: 14-3-3ζ; HEK-293 cells; Nuclear trafficking; PP1α