Promyelocytic leukemia nuclear bodies support a late step in DNA double-strand break repair by homologous recombination.
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.
The Human Genetics Institute of New Jersey, Rutgers University, Piscataway, New Jersey, USA.
Percy Luk
PL
Yeung
Natalia G
NG
Denissova
Cara
C
Nasello
Zhanna
Z
Hakhverdyan
J Don
JD
Chen
Mark A
MA
Brenneman
D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism / Q000473:pathology; D053903:DNA Breaks, Double-Stranded; D059766:DNA End-Joining Repair; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D042822:Genomic Instability; D006657:Histones / Q000378:metabolism; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism; D010087:Oxides / Q000494:pharmacology; D010766:Phosphorylation; D000071156:Promyelocytic Leukemia Protein; D034622:RNA Interference; D051135:Rad51 Recombinase / Q000378:metabolism; D059767:Recombinational DNA Repair / Q000187:drug effects; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
D001152:Arsenicals; D004273:DNA, Neoplasm; C468783:H2AX protein, human; D006657:Histones; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D010087:Oxides; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; C070576:PML protein, human; D014212:Tretinoin; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000077237:Arsenic Trioxide