title: PCNA-interacting peptides reduce Akt phosphorylation and TLR-mediated cytokine secretion suggesting a role of PCNA in cellular signaling.
abstract: Proliferating cell nuclear antigen (PCNA), commonly known as a nuclear protein essential for regulation of DNA replication, DNA repair, and epigenetics, has recently been associated with multiple cytosolic functions. Many proteins containing one of the two known PCNA-interacting motifs, the AlkB homologue 2 PCNA interacting motif (APIM) and the PCNA-interacting peptide (PIP)-box, are considered to be mainly cytosolic. APIM is found in more than 20 kinases and/or associated proteins including several direct or indirect members of the mitogen-activated protein kinase (MAPK) and PI3K/Akt pathways. Mass spectrometry analysis of PCNA-pull downs verified that many cytosolic proteins involved in the MAPK and PI3K/Akt pathways are in complex with PCNA. Furthermore, treatment of cells with a PCNA-interacting APIM-containing peptide (APIM-peptide) reduced Akt phosphorylation in human peripheral blood monocytes and a human keratinocyte cell line (HaCaT). Additionally, the APIM-peptide strongly reduced the cytokine secretion from monocytes stimulated with toll like receptor (TLR) ligands and potentiated the effects of MAPK and PI3K/Akt inhibitors. Interestingly, the protein level of the APIM-containing PKR/RIG-1 activator protein (PACT) was initially strongly reduced in HaCaT cells stimulated with APIM-peptide in combination with the TLR ligand polyinosinic-polycytidylic acid (polyIC). Our results suggest that PCNA has a platform role in cytosol affecting cellular signaling.
authors: Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7489 Trondheim, Norway.
authors: Camilla
authors: C
authors: Olaisen
authors: Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7489 Trondheim, Norway.
authors: Rebekka
authors: R
authors: Müller
authors: Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7489 Trondheim, Norway.
authors: Aina
authors: A
authors: Nedal
authors: Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7489 Trondheim, Norway. Electronic address: marit.otterlei@ntnu.no.
authors: Marit
authors: M
authors: Otterlei
mesh_terms: D000595:Amino Acid Sequence; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D018613:Microscopy, Confocal; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051193:Toll-Like Receptors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D016207:Cytokines; D020928:Mitogen-Activated Protein Kinases; D010455:Peptides; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D018809:Proliferating Cell Nuclear Antigen; D051057:Proto-Oncogene Proteins c-akt; D016601:RNA-Binding Proteins; D051193:Toll-Like Receptors; C104647:PRKRA protein, human
keywords: APIM; MAPK; PCNA; PI3K/Akt; TLR