Premium
Promyelocytic leukemia nuclear bodies support a late step in DNA double‐strand break repair by homologous recombination
Author(s) -
Yeung Percy Luk,
Denissova Natalia G.,
Nasello Cara,
Hakhverdyan Zhanna,
Chen J. Don,
Brenneman Mark A.
Publication year - 2012
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.24050
Subject(s) - promyelocytic leukemia protein , rad51 , biology , gene knockdown , homologous recombination , dna damage , acute promyelocytic leukemia , dna repair , microbiology and biotechnology , dna , genome instability , cancer research , retinoic acid , gene , genetics
The PML protein and PML nuclear bodies (PML‐NB) are implicated in multiple cellular functions relevant to tumor suppression, including DNA damage response. In most cases of acute promyelocytic leukemia, the PML and retinoic acid receptor alpha ( RARA ) genes are translocated, resulting in expression of oncogenic PML‐RARα fusion proteins. PML‐NB fail to form normally, and promyelocytes remain in an undifferentiated, abnormally proliferative state. We examined the involvement of PML protein and PML‐NB in homologous recombinational repair (HRR) of chromosomal DNA double‐strand breaks. Transient overexpression of wild‐type PML protein isoforms produced hugely enlarged or aggregated PML‐NB and reduced HRR by ∼2‐fold, suggesting that HRR depends to some extent upon normal PML‐NB structure. Knockdown of PML by RNA interference sharply attenuated formation of PML‐NB and reduced HRR by up to 20‐fold. However, PML‐knockdown cells showed apparently normal induction of H2AX phosphorylation and RAD51 foci after DNA damage by ionizing radiation. These findings indicate that early steps in HRR, including recognition of DNA double‐strand breaks, initial processing of ends, and assembly of single‐stranded DNA/RAD51 nucleoprotein filaments, do not depend upon PML‐NB. The HRR deficit in PML‐depleted cells thus reflects inhibition of later steps in the repair pathway. Expression of PML‐RARα fusion proteins disrupted PML‐NB structure and reduced HRR by up to 10‐fold, raising the possibility that defective HRR and resulting genomic instability may figure in the pathogenesis, progression and relapse of acute promyelocytic leukemia. J. Cell. Biochem. 113: 1787–1799, 2012. © 2011 Wiley Periodicals, Inc.