title: Modulation of transglutaminase 2 activity in H9c2 cells by PKC and PKA signalling: a role for transglutaminase 2 in cytoprotection.
abstract: OBJECTIVE
  Tissue transglutaminase (TG2) has been shown to mediate cell survival in many cell types. In this study, we investigated whether the role of TG2 in cytoprotection was mediated by the activation of PKA and PKC in cardiomyocyte-like H9c2 cells.
  
  
  METHODS
  H9c2 cells were extracted following stimulation with phorbol-12-myristate-13-acetate (PMA) and forskolin. Transglutaminase activity was determined using an amine incorporating and a protein crosslinking assay. The presence of TG isoforms (TG1, 2, 3) was determined using Western blot analysis. The role of TG2 in PMA- and forskolin-induced cytoprotection was investigated by monitoring H₂O₂-induced oxidative stress in H9c2 cells.
  
  
  RESULTS
  Western blotting showed TG2 >> TG1 protein expression but no detectable TG3. The amine incorporating activity of TG2 in H9c2 cells increased in a time and concentration-dependent manner following stimulation with PMA and forskolin. PMA and forskolin-induced TG2 activity was blocked by PKC (Ro 31-8220) and PKA (KT 5720 and Rp-8-Cl-cAMPS) inhibitors respectively. The PMA- and forskolin-induced increases in TG2 activity were attenuated by the TG2 inhibitors Z-DON and R283. Immunocytochemistry revealed TG2-mediated biotin-X-cadaverine incorporation into proteins and proteomic analysis identified known (β-tubulin) and novel (α-actinin) protein substrates for TG2. Pretreatment with PMA and forskolin reversed H2 O2 -induced decrease in MTT reduction and release of LDH. TG2 inhibitors R283 and Z-DON blocked PMA- and forskolin-induced cytoprotection.
  
  
  CONCLUSIONS
  TG2 activity was stimulated via PKA- and PKC-dependent signalling pathways in H9c2 cells These results suggest a role for TG2 in cytoprotection induced by these kinases.
authors.affiliation: School of Science and Technology, Nottingham Trent University, Nottingham, UK.
authors.forename: Ibtesam
authors.initials: I
authors.lastname: Almami
authors.forename: John M
authors.initials: JM
authors.lastname: Dickenson
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Hargreaves
authors.forename: Philip L R
authors.initials: PL
authors.lastname: Bonner
mesh_terms: D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011758:Pyrroles / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D011503:Transglutaminases / Q000378:metabolism*
chemical_list: D002227:Carbazoles; D007211:Indoles; D047428:Protein Kinase Inhibitors; D011758:Pyrroles; C000717609:Tgm2 protein, rat; C074155:8-chloroadenosine-3',5'-cyclic monophosphorothioate; D005576:Colforsin; C057416:KT 5720; D000242:Cyclic AMP; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate; C064758:Ro 31-8220