Browsing by Subject "Double-strand break responses"
Now showing 1 - 1 of 1
- Results Per Page
- Sort Options
Item Poly(ADP-ribose) polymerase-1 : protein substrates identification and biological functions characterization(2018-05-02) Chen, Jung-Kuei; Liu, Hung-wen, 1952-; Whitman, Christian P.; Hoffman, David W.; Kim, Jonghwan; Miller, Kyle M.PARP-1 catalyzes poly(ADP-ribosyl)ation reaction to mediate various cellular processes including DNA repair, chromatin remodelling, transcription, inflammation, and cell death. Despite its discovery for more than fifty years, many fundamental questions regarding the roles of PARP-1 in various DNA repair pathways remain unresolved. By comparing all available mass spectrometry-based screens to identify PARP-1 substrate proteins, cold-inducible RNA-binding protein (CIRBP) was commonly found to associate with PARP-1. Here I identify cold-inducible RNA-binding protein (CIRBP) as a newly identified key regulator in DNA double-strand break (DSB) repair. On DNA damage, CIRBP temporarily accumulates at the damaged regions and is poly(ADP ribosyl)ated by poly(ADP ribose) polymerase-1 (PARP-1). Its dissociation from the sites of damage may depend on its phosphorylation status as mediated by phosphatidylinositol 3-kinase-related kinases. In the absence of CIRBP, cells showed reduced γH2AX, Rad51, and 53BP1 foci formation. Moreover, CIRBP-depleted cells exhibited impaired homologous recombination, impaired nonhomologous endjoining, increased micronuclei formation, and higher sensitivity to gamma irradiation, demonstrating the active involvement of CIRBP in DSB repair. Furthermore, CIRBP depleted cells exhibited defects in DNA damage-induced chromatin association of the MRN complex (Mre11, Rad50, and NBS1) and ATM kinase. CIRBP depletion also reduced phosphorylation of a variety of ATM substrate proteins and thus impaired the DNA damage response. The role of PARP-1 in mediating DNA/RNA hybrid (R-loop) formation was also explored. Programmed R-loop formation was required to regulate diverse cellular processes, but uncontrolled R-loops accumulation is also a source of genome instability. The preliminary data suggest that PARP-1 interacts with several nucleolus proteins, and depletion of PARP-1 or these nucleolus proteins induces R-loop accumulation. Taken together, these results provide a better understanding of PARP-1 in DNA damage responses and genome integrity.