title: p90 ribosomal S6 kinase 2 is associated with and dephosphorylated by protein phosphatase 2Cdelta.
abstract: RSK2 (p90 ribosomal S6 kinase 2) is activated via the ERK (extracellular-signal-regulated kinase) pathway by phosphorylation on four sites: Ser227 in the activation loop of the N-terminal kinase domain, Ser369 in the linker, Ser386 in the hydrophobic motif and Thr577 in the C-terminal kinase domain of RSK2. In the present study, we demonstrate that RSK2 is associated in vivo with PP2Cdelta (protein phosphatase 2Cdelta). In epidermal growth factorstimulated cells, RSK2 is partially dephosphorylated on all four sites in an Mn2+-dependent manner, leading to reduced protein kinase activity. Furthermore, PP2Cd is phosphorylated by ERK on Thr315 and Thr333 in the catalytic domain. Mutation of Thr315 and Thr333 to alanine in a catalytically inactive mutant PP2Cdelta (H154D) (His154-->Asp) increases the association with RSK2 significantly, whereas mutation to glutamate, mimicking phosphorylation, reduces the binding of RSK2. The domains of interaction are mapped to the N-terminal extension comprising residues 1-71 of PP2Cd and the N-terminal kinase domain of RSK2. The interaction is specific, since PP2Cd associates with RSK1-RSK4, MSK1 (mitogen- and stress-activated kinase 1) and MSK2, but not with p70 S6 kinase or phosphoinositide-dependent kinase 1. We conclude that RSK2 is associated with PP2Cd in vivo and is partially dephosphorylated by it, leading to reduced kinase activity.
authors.affiliation: Department of Clinical Biochemistry, Glostrup Hospital, DK 2600 Glostrup, Denmark. ud@dcb-glostrup.dk
authors.forename: Ulrik
authors.initials: U
authors.lastname: Doehn
authors.forename: Steen
authors.initials: S
authors.lastname: Gammeltoft
authors.forename: Shi-Hsiang
authors.initials: SH
authors.lastname: Shen
authors.forename: Claus J
authors.initials: CJ
authors.lastname: Jensen
mesh_terms: D000818:Animals; D019556:COS Cells / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D020134:Catalytic Domain / Q000502:physiology; D002460:Cell Line; D002522:Chlorocebus aethiops; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology / Q000201:enzymology; D009154:Mutation / Q000235:genetics / Q000502:physiology; D010455:Peptides / Q000378:metabolism / Q000502:physiology; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism; D025941:Protein Interaction Mapping / Q000379:methods; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism*
chemical_list: D010455:Peptides; D010770:Phosphotransferases; D017346:Protein Serine-Threonine Kinases; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C069330:ribosomal protein S6 kinase, 90kDa, polypeptide 3; D048049:Extracellular Signal-Regulated MAP Kinases; D010749:Phosphoprotein Phosphatases