ATM phosphorylation of Nijmegen breakage syndrome protein is required in a DNA damage response.
Nijmegen breakage syndrome (NBS) is characterized by extreme radiation sensitivity, chromosomal instability and cancer. The phenotypes are similar to those of ataxia telangiectasia mutated (ATM) disease, where there is a deficiency in a protein kinase that is activated by DNA damage, indicating that the Nbs and Atm proteins may participate in common pathways. Here we report that Nbs is specifically phosphorylated in response to gamma-radiation, ultraviolet light and exposure to hydroxyurea. Phosphorylation of Nbs mediated by gamma-radiation, but not that induced by hydroxyurea or ultraviolet light, was markedly reduced in ATM cells. In vivo, Nbs was phosphorylated on many serine residues, of which S343, S397 and S615 were phosphorylated by Atm in vitro. At least two of these sites were underphosphorylated in ATM cells. Inactivation of these serines by mutation partially abrogated Atm-dependent phosphorylation. Reconstituting NBS cells with a mutant form of Nbs that cannot be phosphorylated at selected, ATM-dependent serine residues led to a specific reduction in clonogenic survival after gamma-radiation. Thus, phosphorylation of Nbs by Atm is critical for certain responses of human cells to DNA damage.
Wu
X
X
Dana Farber Cancer Institute, Boston, Massachusetts 02115, USA.
Ranganathan
V
V
Weisman
D S
DS
Heine
W F
WF
Ciccone
D N
DN
O'Neill
T B
TB
Crick
K E
KE
Pierce
K A
KA
Lane
W S
WS
Rathbun
G
G
Livingston
D M
DM
Weaver
D T
DT
D001260:Ataxia Telangiectasia / Q000235:genetics*; D064007:Ataxia Telangiectasia Mutated Proteins; D002384:Catalysis; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D019457:Chromosome Breakage; D004249:DNA Damage; D004268:DNA-Binding Proteins; D005720:Gamma Rays; D006801:Humans; D009369:Neoplasms / Q000235:genetics; D009687:Nuclear Proteins; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011836:Radiation Tolerance / Q000235:genetics; D012694:Serine / Q000378:metabolism; D013577:Syndrome; D025521:Tumor Suppressor Proteins
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C112156:NBN protein, human; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; D012694:Serine; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases