title: ERK1/2-dependent activation of mTOR/mTORC1/p70S6K regulates thrombin-induced RPE cell proliferation.
abstract: Epithelial-mesenchymal transition (EMT), proliferation and migration of RPE cells characterize the development of proliferative vitreoretinopathy (PVR) and other fibro-proliferative eye diseases leading to blindness. A common event in these pathologies is the alteration of the BRB which allows the interaction of RPE cells with thrombin, a pro-inflammatory protease contained in serum. Thrombin promotion of cytoskeletal reorganization, proliferation, and migration has been reported in different cell types, although the molecular mechanisms involved in these processes remain poorly understood. Our previous work demonstrated that thrombin promotes RPE cell proliferation, cytoskeletal remodeling and migration, hallmark processes in the development of PVR. Thrombin induction of RPE cell proliferation requires PI3K, PDK1, and Akt/PKB (Akt) signaling leading to cyclin D1 gene expression. Since Akt functions as an upstream activator of mechanistic target of rapamycin complex 1 (mTORC1) and is also a downstream target for mTORC2, the aim of this work was to determine whether mTOR is involved in thrombin-induced RPE cell proliferation by regulating cyclin D1 expression in immortalized rat RPE-J cell line. Results demonstrate that thrombin-induced cyclin D1 expression and cell proliferation require Akt-independent phosphorylation/activation of mTOR at Ser 2448 mediated by PI3K/PKC-ζ/ERK1/2 signaling, concomitant to Akt-dependent activation of p70S6K carried by mTORC1.
authors.affiliation: División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México (UNAM), México, D. F., Mexico.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Parrales
authors.forename: Edith
authors.initials: E
authors.lastname: López
authors.forename: Irene
authors.initials: I
authors.lastname: Lee-Rivera
authors.forename: Ana María
authors.initials: AM
authors.lastname: López-Colomé
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D019938:Cyclin D1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D034622:RNA Interference; D034741:RNA, Small Interfering; D000076226:Rapamycin-Insensitive Companion of mTOR Protein; D051381:Rats; D000076223:Regulatory-Associated Protein of mTOR; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology*
chemical_list: D002352:Carrier Proteins; D019938:Cyclin D1; D047908:Intracellular Signaling Peptides and Proteins; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D034741:RNA, Small Interfering; D000076226:Rapamycin-Insensitive Companion of mTOR Protein; D000076223:Regulatory-Associated Protein of mTOR; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D013917:Thrombin; C000631434:Pdk1 protein, rat; C572458:Rptor protein, rat; C550254:rictor protein, rat