title: Regulation of TNF-alpha-activated PKC-zeta signaling by the human biliverdin reductase: identification of activating and inhibitory domains of the reductase.
abstract: Human biliverdin reductase (hBVR) is a dual function enzyme: a catalyst for bilirubin formation and a S/T/Y kinase that shares activators with protein kinase C (PKC) -zeta, including cytokines, insulin, and reactive oxygen species (ROS). Presently, we show that hBVR increases PKC-zeta autophosphorylation, stimulation by TNF-alpha, as well as cytokine stimulation of NF-kappaB DNA binding and promoter activity. S149 in hBVR S/T kinase domain and S230 in YLS230F in hBVR's docking site for the SH2 domain of signaling proteins are phosphorylation targets of PKC-zeta. Two hBVR-based peptides, KRNRYLS230F (#1) and KKRILHC281 (#2), but not their S-->A or C-->A derivatives, respectively, blocked PKC-zeta stimulation by TNF-alpha and its membrane translocation. The C-terminal-based peptide KYCCSRK296 (#3), enhanced PKC-zeta stimulation by TNF-alpha; for this, Lys296 was essential. In metabolically 32P-labeled HEK293 cells transfected with hBVR or PKC-zeta, TNF-alpha increased hBVR phosphorylation. TNF-alpha did not stimulate PKC-zeta in cells infected with small interfering RNA for hBVR or transfected with hBVR with a point mutation in the nucleotide-binding loop (G17), S149, or S230; this was similar to the response of "kinase-dead" PKC-zeta(K281R). We suggest peptide #1 blocks PKC-zeta-docking site interaction, peptide #2 disrupts function of the PKC-zeta C1 domain, and peptide #3 alters ATP presentation to the kinase. The findings are of potential significance for development of modulators of PKC-zeta activity and cellular response to cytokines.
authors.affiliation: University of Rochester School of Medicine and Dentistry, Department of Biochemistry and Biophysics, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Lerner-Marmarosh
authors.forename: Tihomir
authors.initials: T
authors.lastname: Miralem
authors.forename: Peter E M
authors.initials: PE
authors.lastname: Gibbs
authors.forename: Mahin D
authors.initials: MD
authors.lastname: Maines
mesh_terms: D002460:Cell Line; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry* / Q000502:physiology*; D010446:Peptide Fragments / Q000737:chemistry / Q000502:physiology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000502:physiology*; D000099221:Protein Kinase C zeta
chemical_list: D007527:Isoenzymes; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010446:Peptide Fragments; D011493:Protein Kinase C; D047428:Protein Kinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; D000099221:Protein Kinase C zeta; C019789:biliverdin reductase