title: RACK1 mediates activation of JNK by protein kinase C [corrected].
abstract: Activation of the Jun-N-terminal kinase (JNK) signaling cascade by phorbol esters (TPA) or protein kinase C (PKC) is well documented, although the underlying mechanism is not known. Here, we demonstrate that the receptor for activated C kinase 1 (RACK1) serves as an adaptor for PKC-mediated JNK activation. Phosphorylation of JNK by PKC occurs on Ser129 and requires the presence of RACK1. Ser129 phosphorylation augments JNK phosphorylation by MKK4 and/or MKK7 and is required for JNK activation by TPA, TNFalpha, UV irradiation, and PKC, but not by anisomycin or MEKK1. Inhibition of RACK1 expression by siRNA attenuates JNK activation, sensitizes melanoma cells to UV-induced apoptosis, and reduces their tumorigenicity in nude mice. In finding the role of RACK1 in activation of JNK by PKC, our study also highlights the nature of crosstalk between these two signal-transduction pathways.
authors.affiliation: Department of Oncological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA.
authors.forename: Pablo
authors.initials: P
authors.lastname: López-Bergami
authors.forename: Hasem
authors.initials: H
authors.lastname: Habelhah
authors.forename: Anindita
authors.initials: A
authors.lastname: Bhoumik
authors.forename: Weizhou
authors.initials: W
authors.lastname: Zhang
authors.forename: Lu-Hai
authors.initials: LH
authors.lastname: Wang
authors.forename: Ze'ev
authors.initials: Z
authors.lastname: Ronai
mesh_terms: D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D045163:Antibodies, Phospho-Specific / Q000378:metabolism; D017209:Apoptosis; D001665:Binding Sites; D002227:Carbazoles / Q000494:pharmacology; D002384:Catalysis / Q000187:drug effects; D002460:Cell Line; D045744:Cell Line, Tumor; D003593:Cytoplasm / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins; D017353:Gene Deletion; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism; D048688:MAP Kinase Kinase 7 / Q000235:genetics / Q000378:metabolism; D048728:MAP Kinase Kinase Kinase 1 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D048055:Mitogen-Activated Protein Kinase 8 / Q000235:genetics / Q000378:metabolism; D048056:Mitogen-Activated Protein Kinase 9 / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010748:Phosphopeptides / Q000032:analysis; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D064546:Protein Kinase C beta; D034741:RNA, Small Interfering / Q000235:genetics; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D045163:Antibodies, Phospho-Specific; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D009363:Neoplasm Proteins; D010748:Phosphopeptides; C419368:RACK1 protein, human; D034741:RNA, Small Interfering; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D014409:Tumor Necrosis Factor-alpha; C081021:Go 6976; D012694:Serine; D000841:Anisomycin; D048056:Mitogen-Activated Protein Kinase 9; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D048031:JNK Mitogen-Activated Protein Kinases; D048055:Mitogen-Activated Protein Kinase 8; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D048670:MAP Kinase Kinase 4; D048688:MAP Kinase Kinase 7; C482559:MAP2K4 protein, human; C482569:MAP2K7 protein, human; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate