The DNA damage response in DNA-dependent protein kinase-deficient SCID mouse cells: replication protein A hyperphosphorylation and p53 induction.
Proc Natl Acad Sci U S A
; 93(24): 13825-30, 1996 Nov 26.
Article
em En
| MEDLINE
| ID: mdl-8943020
ABSTRACT
Severe combined immunodeficient (SCID) mice display an increased sensitivity to ionizing radiation compared with the parental, C.B-17, strain due to a deficiency in DNA double-strand break repair. The catalytic subunit of DNA-dependent protein kinase (DNA-PKCS) has previously been identified as a strong candidate for the SCID gene. DNA-PK phosphorylates many proteins in vitro, including p53 and replication protein A (RPA), two proteins involved in the response of cells of DNA damage. To determine whether p53 and RPA are also substrates of DNA-PK in vivo following DNA damage, we compared the response of SCID and MO59J (human DNA-PKcs-deficient glioblastoma) cells with their respective wild-type parents following ionizing radiation. Our findings indicate that (i) p53 levels are increased in SCID cells following ionizing radiation, and (ii) RPA p34 is hyperphosphorylated in both SCID cells and MO59J cells following ionizing radiation. The hyperphosphorylation of RPA p34 in vivo is concordant with a decrease in the binding of RPA to single-stranded DNA in crude extracts derived from both C.B-17 and SCID cells. These results suggest that DNA-PK is not the only kinase capable of phosphorylating RPA. We conclude that the DNA damage response involving p53 and RPA is not associated with the defect in DNA repair in SCID cells and that the physiological substrate(s) for DNA-PK essential for DNA repair has not yet been identified.
Texto completo:
1
Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Dano ao DNA
/
Proteína Supressora de Tumor p53
/
Proteínas Serina-Treonina Quinases
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Proteínas de Ligação a DNA
/
Replicação do DNA
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Estados Unidos