title: PI3-kinase p85alpha is a target molecule of proline-rich antimicrobial peptide to suppress proliferation of ras-transformed cells.
abstract: PR-39, which is an endogenous antimicrobial peptide, can bind to Src homology 3 domains of the NADPH complex protein p47(phox) and the signaling adapter protein p130(Cas). Recently, we have reported that PR-39 gene transduction altered invasive activity and actin structure of human hepatocellular carcinoma cells, suggesting that this peptide affects cellular signaling due to its proline-rich motif. In order to clarify the mechanism of the PR-39 functions, we transfected the PR-39 gene into mouse NIH3T3 cells which had already been transformed with human activated k-ras gene. The PR-39 gene transfectant showed a reorganization of actin structure and suppression of cell proliferation both in vitro and in vivo. Decreases of MAP (mitogen-activated protein) kinase activity, cyclin D1 expression and JNK activity were observed in the PR-39 gene transfectant. Co-immunoprecipitation analysis revealed that PR-39 binds to PI3-kinase p85alpha, which is a regulatory subunit of PI3-kinase and one of the effectors by which ras induces cytoskeletal changes and stimulates mitogenesis. The PI3-kinase activity of the PR-39 gene transfectant was decreased compared with that of the ras transformant. These results suggest that PR-39 alters actin structure and cell proliferation rate by binding to PI3-kinase p85alpha and suppressing the PI3-kinase activity.
authors.affiliation: Third Department of Internal Medicine, Asahikawa Medical College, Asahikawa 078-8510, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: Y
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: Y
authors.initials: Y
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Ohtake
authors.forename: H
authors.initials: H
authors.lastname: Saito
authors.forename: Y
authors.initials: Y
authors.lastname: Kohgo
mesh_terms: D016475:3T3 Cells / Q000201:enzymology / Q000648:ultrastructure; D008841:Actin Cytoskeleton / Q000648:ultrastructure; D020816:Amino Acid Motifs; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D002455:Cell Division; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D019938:Cyclin D1 / Q000096:biosynthesis / Q000235:genetics; D003599:Cytoskeleton / Q000648:ultrastructure; D004790:Enzyme Induction; D011905:Genes, ras; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D020935:MAP Kinase Signaling System; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis / Q000235:genetics; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000737:chemistry / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013552:Swine / Q000235:genetics; D014162:Transfection; D018909:src Homology Domains
chemical_list: D023181:Antimicrobial Cationic Peptides; D019938:Cyclin D1; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D009363:Neoplasm Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011993:Recombinant Fusion Proteins; C072212:PR 39