p53 promotes the fidelity of DNA end-joining activity by, in part, enhancing the expression of heterogeneous nuclear ribonucleoprotein G.
Many studies have suggested the involvement of wild-type (wt) p53 in the repair of DNA double-strand breaks (DSBs) via DNA end-joining (EJ) process. To investigate this possibility, we compared the capacity and fidelity of DNA EJ in RKO cells containing wt p53 and RKO cells containing no p53 (RKO cells with p53 knockdown). The p53 knockdown cells showed lower fidelity of DNA EJ compared to the control RKO cells. The DNA end-protection assay revealed the association of a protein complex including heterogeneous nuclear ribonucleoprotein G (hnRNP G) with the DNA ends in RKO cells containing wt p53, but not with the DNA ends in RKO cells with p53 knockdown. Depletion of endogenous hnRNP G notably diminished the fidelity of EJ in RKO cells expressing wt p53. Moreover, an ectopic expression of hnRNP G significantly enhanced the fidelity of DNA EJ and the protection of DNA ends in human cancer cells lacking hnRNP G protein or containing mutant hnRNP G. Finally, using recombinant hnRNP G proteins, we demonstrated the hnRNP G protein is able to bind to and protect DNA ends from degradation of nucleases. Our results suggest that wt p53 modulates DNA DSB repair by, in part, inducing hnRNP G, and the ability of hnRNP G to bind and protect DNA ends may contribute its ability to promote the fidelity of DNA EJ.
Shin
Ki-Hyuk
KH
UCLA School of Dentistry, Los Angeles, CA 90095, USA.
Kim
Reuben H
RH
Kang
Mo K
MK
Kim
Roy H
RH
Kim
Steve G
SG
Lim
Philip K
PK
Yochim
Ji Min
JM
Baluda
Marcel A
MA
Park
No-Hee
NH
D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D005822:Genetic Vectors; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D034441:Heterogeneous-Nuclear Ribonucleoproteins; C510272:RBMX protein, human; D034741:RNA, Small Interfering; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D004247:DNA