Olaisen Camilla, Müller Rebekka, Nedal Aina, Otterlei Marit
Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7489 Trondheim, Norway.
Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7489 Trondheim, Norway.
Cell Signal. 2015 Jul;27(7):1478-87. doi: 10.1016/j.cellsig.2015.03.009. Epub 2015 Mar 20.
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.
增殖细胞核抗原（PCNA），通常被认为是一种对DNA复制、DNA修复和表观遗传学调控至关重要的核蛋白，最近被发现与多种胞质功能有关。许多含有两种已知的PCNA相互作用基序之一的蛋白质，即AlkB同源物2 PCNA相互作用基序（APIM）和PCNA相互作用肽（PIP）框，被认为主要存在于胞质中。APIM存在于20多种激酶和/或相关蛋白中，包括丝裂原活化蛋白激酶（MAPK）和PI3K/Akt信号通路的几个直接或间接成员。对PCNA下拉产物的质谱分析证实，许多参与MAPK和PI3K/Akt信号通路的胞质蛋白与PCNA形成复合物。此外，用含PCNA相互作用APIM的肽（APIM肽）处理细胞可降低人外周血单核细胞和人角质形成细胞系（HaCaT）中Akt的磷酸化水平。此外，APIM肽可显著减少经Toll样受体（TLR）配体刺激的单核细胞分泌细胞因子，并增强MAPK和PI3K/Akt抑制剂的作用。有趣的是，在用APIM肽与TLR配体聚肌苷酸-聚胞苷酸（polyIC）联合刺激的HaCaT细胞中，含APIM的PKR/RIG-1激活蛋白（PACT）的蛋白水平最初会显著降低。我们的结果表明，PCNA在胞质中具有影响细胞信号传导的平台作用。
