dc.creator | Liu, Hanjian | |
dc.date.accessioned | 2020-08-22T21:02:39Z | |
dc.date.available | 2010-01-15 | |
dc.date.issued | 2007-10-03 | |
dc.identifier.uri | https://etd.library.vanderbilt.edu/etd-09152007-110210 | |
dc.identifier.uri | http://hdl.handle.net/1803/14148 | |
dc.description.abstract | DNA damaging agents have been shown to stimulate the localization of human DNA helicase B (HDHB) in nuclear foci, suggesting that HDHB might participate in DNA damage response. In the first part of this dissertation, we found that the chromatin-associated fraction of HDHB increases in cells exposed to a variety of DNA damaging agents. HDHB chromatin accumulation is most prominent in S phase cells exposed to agents that cause replication fork stalling or collapse. Inhibition of checkpoint kinases does not prevent damage-induced accumulation of HDHB on chromatin, suggesting that HDHB associates directly with DNA lesions or with other proteins recruited to lesions. Silencing of HDHB does not affect UV-induced RPA focus formation, but diminishes induction of TopBP1 foci. DNA damage induced CHK1 phosphorylation is impaired in HDHB-depleted cells. These results identify HDHB as a novel factor that associates with damaged chromatin and promotes intra-S phase damage responses.
In the second part of this dissertation, we further investigated the possible function of HDHB in homologous recombination. HDHB-depleted cells showed more aphidicolin-induced chromosome breaks than control-depleted cells. HDHB-depleted cells have fewer sister chromatid exchange than control-depleted cells. An in vivo recombination assay showed that HDHB silencing results in impaired homologous recombination. In vitro, recombinant HDHB stimulates Rad51-mediated 5’-3’ heteroduplex extension. Our studies suggest a function of HDHB in stimulating ssDNA/duplex structure during homologous recombination. | |
dc.format.mimetype | application/pdf | |
dc.subject | chromatin association | |
dc.subject | DNA damage response | |
dc.subject | helicase | |
dc.subject | homologous recombination | |
dc.subject | ATR | |
dc.subject | DNA repair | |
dc.title | Human DNA helicase B functions in DNA damage response and homologous recombination | |
dc.type | dissertation | |
dc.contributor.committeeMember | Eugene Oltz | |
dc.contributor.committeeMember | David Cortez | |
dc.contributor.committeeMember | Ellen Fanning | |
dc.contributor.committeeMember | Jennifer Pietenpol | |
dc.type.material | text | |
thesis.degree.name | PHD | |
thesis.degree.level | dissertation | |
thesis.degree.discipline | Biological Sciences | |
thesis.degree.grantor | Vanderbilt University | |
local.embargo.terms | 2010-01-15 | |
local.embargo.lift | 2010-01-15 | |
dc.contributor.committeeChair | James Patton | |