title: Tissue transglutaminase mediates activation of RhoA and MAP kinase pathways during retinoic acid-induced neuronal differentiation of SH-SY5Y cells.
abstract: All-trans-retinoic acid (RA) plays a crucial role in survival and differentiation of neurons. For elucidating signaling mechanisms involved in RA-induced neuronal differentiation, we have selected SH-SY5Y cells, which are an established in vitro cell model for studying RA signaling. Here we report that RA-induced neuronal differentiation of SH-SY5Y cells is coupled with increased expression/activation of TGase and in vivo transamidation and activation of RhoA. In addition, RA promotes formation of stress fibers and focal adhesion complexes, and activation of ERK1/2, JNK1, and p38alpha/beta/gamma MAP kinases. Using C-3 exoenzyme (RhoA inhibitor) or monodansylcadaverine (TGase inhibitor), we show that transamidated RhoA regulates cytoskeletal rearrangement and activation of ERK1/2 and p38gamma MAP kinases. Further, by using stable SH-SY5Y cell lines (overexpressing wild-type, C277S mutant, and antisense TGase), we demonstrate that transglutaminase activity is required for activation of RhoA, ERK1/2, JNK1, and p38gamma MAP kinases. Activated MAP kinases differentially regulate RA-induced neurite outgrowth and neuronal marker expression. The results of our studies suggest a novel mechanism of RA signaling, which involves activation of TGase and transamidation of RhoA. RA-induced activation of TGase is proposed to induce multiple signaling pathways that regulate neuronal differentiation.
authors.affiliation: Division of Molecular Cardiology, Cardiovascular Research Institute, The Texas A&M University System Health Science Center, College of Medicine, Temple, Texas 76504, USA. Usingh@medicine.tamu.edu
authors.forename: Ugra S
authors.initials: US
authors.lastname: Singh
authors.forename: Jing
authors.initials: J
authors.lastname: Pan
authors.forename: Yu-Lin
authors.initials: YL
authors.lastname: Kao
authors.forename: Suchitra
authors.initials: S
authors.lastname: Joshi
authors.forename: Keri L
authors.initials: KL
authors.lastname: Young
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Baker
mesh_terms: D015415:Biomarkers; D002103:Cadaverine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D048429:Cell Size; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022001:Focal Adhesions / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008954:Models, Biological; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D022502:Stress Fibers / Q000378:metabolism; D011503:Transglutaminases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014212:Tretinoin / Q000378:metabolism* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D004791:Enzyme Inhibitors; D011993:Recombinant Fusion Proteins; D014212:Tretinoin; D011503:Transglutaminases; D020928:Mitogen-Activated Protein Kinases; D020742:rhoA GTP-Binding Protein; C008542:monodansylcadaverine; D002103:Cadaverine