title: p53 induction and activation of DDR1 kinase counteract p53-mediated apoptosis and influence p53 regulation through a positive feedback loop.
abstract: DDR1, discoidin domain receptor 1, belongs to a subfamily of tyrosine kinase receptors with an extracellular domain homologous to Dictyostellium discoideum protein discoidin 1. We showed that DDR1 is a direct p53 transcriptional target, and that DNA damage induced a p53-dependent DDR1 response associated with activation of its tyrosine kinase. We further demonstrated that DDR1 activated the MAPK cascade in a Ras-dependent manner. Whereas levels of p53, phosphoserine-15 p53, p21, ARF and Bcl-X(L) were increased in response to exogenous overexpression of activated DDR1, dominant-negative DDR1 inhibited irradiation-induced MAPK activation and p53, phosphoserine-15 p53, as well as induced p21 and DDR1 levels, suggesting that DDR1 functions in a feedforward loop to increase p53 levels and at least some of its effectors. Nonetheless, inhibition of DDR1 function resulted in strikingly increased apoptosis of wild-type p53-containing cells in response to genotoxic stress through a caspase-dependent pathway. These results strongly imply that this p53 response gene must predominately act to alleviate the adverse effects of stress induced by p53 on its target cell.
authors.affiliation: Cancer Biology Program, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine and Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Pat P
authors.initials: PP
authors.lastname: Ongusaha
authors.forename: Jong-il
authors.initials: JI
authors.lastname: Kim
authors.forename: Li
authors.initials: L
authors.lastname: Fang
authors.forename: Tai W
authors.initials: TW
authors.lastname: Wong
authors.forename: George D
authors.initials: GD
authors.lastname: Yancopoulos
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Aaronson
authors.forename: Sam W
authors.initials: SW
authors.lastname: Lee
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000528:radiation effects; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009153:Mutagens / Q000494:pharmacology; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D011839:Radiation, Ionizing; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
chemical_list: D008164:Luminescent Proteins; D009153:Mutagens; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D049452:Green Fluorescent Proteins; D020794:Receptor Protein-Tyrosine Kinases; D020928:Mitogen-Activated Protein Kinases