title: Oxidative stress induces protein kinase C-mediated activation loop phosphorylation and nuclear redistribution of protein kinase D.
abstract: Oxidative stress induced by cell treatments with H(2)O(2) activates protein kinase D (PKD) via a protein kinase C (PKC)-dependent signal transduction pathway (Waldron, R. T., and Rozengurt, E. (2000) J. Biol. Chem. 275, 17114-17121). Here we show that oxidative stress induces PKC-dependent activation loop Ser(744) and Ser(748) phosphorylation to mediate dose- and time-dependent activation of PKD, both endogenously expressed in Swiss 3T3 cells and stably overexpressed in Swiss 3T3-GFP.PKD cells. Although oxidative stress induced PKD activation loop phosphorylation and activation with identical kinetics, both were dose-dependently blocked by preincubation of cells with selective inhibitors of PKC (GF109203X and Gö6983) or c-Src (PP2). Inhibition of Src tyrosine kinase activity eliminated oxidative stress-induced direct PKD tyrosine phosphorylation, but only partially attenuated activation loop phosphorylation and activation. Mutation of a putative tyrosine phosphorylation site on PKD, Tyr(469) to phenylalanine, had no effect on its activation by oxidative stress in transfected COS-7 cells. Similarly, a mutant with Tyr(469) replaced by aspartic acid had increased basal activity but was also further activated by oxidative stress. Thus, PKD tyrosine phosphorylation at this site neither produced full activation by itself nor was required for oxidative stress-induced activation mediated by activation loop phosphorylation. In addition to PKD activation, activation loop phosphorylation in response to oxidative stress also redistributed activated PKD to cell nuclei, as revealed by PKD indirect immunofluorescence, imaging of a PKD-green fluorescent protein fusion construct (GFP-PKD), and analysis of nuclear pellets. Cell preincubation with Gö6983 strongly diminished H(2)O(2)-induced nuclear relocalization of GFP-PKD. Taken together, these results indicate that PKC-mediated PKD Ser(744) and Ser(748) phosphorylation induced by oxidative stress integrates PKD activation with redistribution to the nucleus.
authors.affiliation: Division of Digestive Diseases, Department of Medicine, UCLA David Geffen School of Medicine, UCLA-CURE Digestive Diseases Research Center and Molecular Biology Institute, UCLA, Los Angeles, California 90095-1786, USA. rwaldron@mednet.ucla.edu
authors.forename: Richard T
authors.initials: RT
authors.lastname: Waldron
authors.forename: Osvaldo
authors.initials: O
authors.lastname: Rey
authors.forename: Elena
authors.initials: E
authors.lastname: Zhukova
authors.forename: Enrique
authors.initials: E
authors.lastname: Rozengurt
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000201:enzymology*; D002522:Chlorocebus aethiops; D004789:Enzyme Activation; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D041701:Swiss 3T3 Cells; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D014443:Tyrosine; D012694:Serine; C089212:protein kinase D; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D000111:Acetylcysteine