HSSB1 and hSSB2 form similar multiprotein complexes that participate in DNA damage response.
hSSB1 (human single strand DNA-binding protein 1) has been shown to participate in homologous recombination (HR)-dependent repair of DNA double strand breaks (DSBs) and ataxia telangiectasia-mutated (ATM)-mediated checkpoint pathways. Here we present evidence that hSSB2, a homolog of hSSB1, plays a role similar to hSSB1 in DNA damage-response pathways. This was evidenced by findings that hSSB2-depleted cells resemble hSSB1-depleted cells in hypersensitivity to DNA-damaging reagents, reduced efficiency in HR-dependent repair of DSBs, and defective ATM-dependent phosphorylation. Notably, hSSB1 and hSSB2 form separate complexes with two identical proteins, INTS3 and hSSBIP1 (C9ORF80). Cells depleted of INTS3 and hSSBIP1 also exhibited hypersensitivity to DNA damage reagents, chromosomal instability, and reduced ATM-dependent phosphorylation. hSSBIP1 was rapidly recruited to laser-induced DSBs, a feature also similar to that reported for hSSB1. Depletion of INTS3 decreased the stability of hSSB1 and hSSBIP1, suggesting that INTS3 may provide a scaffold to allow proper assembly of the hSSB complexes. Thus, our data demonstrate that hSSB1 and hSSB2 form two separate complexes with similar structures, and both are required for efficient HR-dependent repair of DSBs and ATM-dependent signaling pathways.
Li
Yongjiang
Y
Laboratory of Genetics, NIA, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, USA.
Bolderson
Emma
E
Kumar
Rakesh
R
Muniandy
Parameswary A
PA
Xue
Yutong
Y
Richard
Derek J
DJ
Seidman
Michael
M
Pandita
Tej K
TK
Khanna
Kum Kum
KK
Wang
Weidong
W
D002460:Cell Line; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D024101:Mitochondrial Proteins; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding
D004268:DNA-Binding Proteins; C543506:INIP protein, human; C543505:INTS3 protein, human; D024101:Mitochondrial Proteins; D046912:Multiprotein Complexes; C504091:NABP2 protein, human; C477058:SSBP2 protein, human