title: A kinome-targeted RNAi-based screen links FGF signaling to H2AX phosphorylation in response to radiation.
abstract: A general radioprotective effect by fibroblast growth factor (FGF) has been extensively described since the early 1990s; however, the molecular mechanisms involved remain largely unknown. Radiation-induced DNA double-strand breaks (DSBs) lead to a complex set of responses in eukaryotic cells. One of the earliest consequences is phosphorylation of histone H2AX to form nuclear foci of the phosphorylated form of H2AX (γH2AX) in the chromatin adjacent to sites of DSBs and to initiate the recruitment of DNA-repair molecules. Upon a DSB event, a rapid signaling network is activated to coordinate DNA repair with the induction of cell-cycle checkpoints. To date, three kinases (ATM, ATR, and DNA-PK) have been shown to phosphorylate histone H2AX in response to irradiation. Here, we report a kinome-targeted small interfering RNA (siRNA) screen to characterize human kinases involved in H2AX phosphorylation. By analyzing γH2AX foci at a single-nucleus level, we identified 46 kinases involved either directly or indirectly in H2AX phosphorylation in response to irradiation in human keratinocytes. Furthermore, we demonstrate that in response to irradiation, the FGFR4 signaling cascade promotes JNK1 activation and direct H2AX phosphorylation leading, in turn, to more efficient DNA repair. This can explain, at least partially, the radioprotective effect of FGF.
authors.affiliation: CEA, IRTSV, Biologie à Grande Echelle, 17 rue des Martyrs, 38054, Grenoble Cedex, France, benzina16@yahoo.fr.
authors.forename: Sami
authors.initials: S
authors.lastname: Benzina
authors.forename: Amandine
authors.initials: A
authors.lastname: Pitaval
authors.forename: Claudie
authors.initials: C
authors.lastname: Lemercier
authors.forename: Celine
authors.initials: C
authors.lastname: Lustremant
authors.forename: Vincent
authors.initials: V
authors.lastname: Frouin
authors.forename: Ning
authors.initials: N
authors.lastname: Wu
authors.forename: Alexandre
authors.initials: A
authors.lastname: Papine
authors.forename: Françoise
authors.initials: F
authors.lastname: Soussaline
authors.forename: Paul-Henri
authors.initials: PH
authors.lastname: Romeo
authors.forename: Xavier
authors.initials: X
authors.lastname: Gidrol
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects; D004260:DNA Repair / Q000502:physiology; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000502:physiology; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology*; D034622:RNA Interference / Q000502:physiology*; D034741:RNA, Small Interfering / Q000378:metabolism*; D011827:Radiation; D051499:Receptor, Fibroblast Growth Factor, Type 4 / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D005346:Fibroblast Growth Factors; C496371:FGFR4 protein, human; D051499:Receptor, Fibroblast Growth Factor, Type 4; D051747:DNA-Activated Protein Kinase; D048055:Mitogen-Activated Protein Kinase 8